When I was an aspiring Infectious Disease fellow, I marveled at how the ID doctors would come up with diseases that no one else had thought of. How did they do that?
They obtain a detailed patient history. (It’s the ID doctors equivalent of a procedure!)
Contact or exposure to certain animals are associated with certain diseases.
These are examples of some of the questions to ask to ascertain whether your patient has been in contact with specific animals: – Do you have any pets? Do you have frequent contact with anyone else’s pets? – Do you have contact with any farm or wild animals? – What do you do for work (farmer, veterinarian, kennel worker, biologists, etc)? – What do you do for fun (hunting, fishing, cave explorer, raising chickens, etc)?
I’ve created an easy graphic to give you an idea of some diseases that are associated with different animals your patients might encounter. This is to help you quickly look up which infections you should consider in your differential if your patient reports an exposure to one of these animals.
*This list does not include ALL pathogens. This is just a list of the most common plus others to think about in certain situations. In places outside of North America, this list may look different. **This is not intended to take the place of a formal infectious disease consult. ***Use this chart in the context of the clinical presentation. It does not mean you should test for all these infections in every patient, but rather gives you a quick reminder to consider them in your differential.
Was this helpful? Did I miss something? Tell me what you’re thinking with a comment!
1. Centers for Disease Control and Prevention. Healthy Pets Healthy People. http://www.cdc.gov/healthypets/pets/cats.html (Accessed on Feb 23, 2019). 2. Day MJ. Pet-Related Infections. Am Fam Physician. 2016; 94(10):794-802. 3. Goldstein EJC and Abrahamian FM. Diseases Transmitted by Cats. Microbiol Spectr. 2015; 3(5). 4. Chomel BB. Emerging and Re-emerging Zoonoses of Dogs and Cats. Animals (Basel). 2014; 4(3):434-445. 5. Dyer JL, Yager P, Orciari L et al. Rabies surveillance in the United States during 2013. J Am Vet Med Assoc. 2014; 245(10):1111-1123. 6. Boseret G, Losson B, Mainil JG, et al. Zoonoses in pet birds: review and perspectives. Vet Res. 2013; 44(1): 36. 7. Kwon-Chung KJ, Fraser JA, Doering TL, et al. Cryptococcus neoformans and Cryptococcus gattii, the Etiologic Agents of Cryptococcosis. Cold Spring Harb Perspect Med. 2014; 4(7):a019760. 8. National Association of State Public Health Veterinarians, Inc. (NASPHV), Centers for Disease Control and Prevention (CDC). Compendium of measures to prevent disease associated with animals in public settings, 2011: National Association of State Public Health Veterinarians, Inc. MMWR Recomm Rep 2011; 60:1. 9. Kotton CN. Zoonoses from pets other than dogs and cats. UpToDate. Published Jan 2019. Accessed on Feb 23, 2019.
Tuberculosis is the leading cause of death globally from an infectious agent. In 2017, an estimated 10 million people developed TB disease and an estimated 1.6 million died1. A recent study demonstrated that <57% of internal medicine housestaff across 7 academic institutions in the U.S. correctly answered 9 out of 10 questions assessing knowledge of assessment and diagnosis of tuberculosis2. This post addresses these questions and to helps clarify latent vs. active TB in a clinical setting.
The primary focus for this blog post is pulmonary TB. Be aware that although the most common presentation of TB is with pulmonary symptoms, TB can present anywhere in the body and sometimes can present without pulmonary symptoms.
But first, definitions.
Latent infection – the bacteria lies dormant in the body and does not cause any symptoms, typically tests for latent infection (see later section) will be positive
Active disease – the individual is experiencing symptoms due to the infection in the body, typically with characteristic imaging findings and microbiological confirmation
Primary disease – immediate onset of active disease after infection
Reactivation disease – onset of active disease after a period of latent infection
Extra-pulmonary disease – presence of bacteria outside of the lungs (the primary organ of infection)
Disseminated disease – two or more noncontiguous sites resulting from lymphohematogenous dissemination
Miliary disease – lesions in the lung that resemble millet seeds; seen in some cases of disseminated TB
Step 1: Risk stratification
Risk factors for TB exposure
having close contact with individuals who have active tuberculosis (roommates, family, friends, caregivers)
living/had lived in a country that is endemic for TB
living/working in a prison
living/working in a homeless shelter
living/working in any other facility/institution that has high rate of TB (hospitals, nursing homes, residential homes for HIV patients)
*USPSTF gives a grade B recommendation for screening those at increased risk (see list above) for latent tuberculosis infection4
Risk factors for TB reactivation
A. Normal host
5-10% of reactivating TB in a lifetime6,13
50% of that 5-10% is within the first 2-5 years of infection6,13
B. Age – immunity weakens in the elderly
End stage renal disease
Corticosteroid or TNF-alpha inhibitor use
Step 2: Why is it important to distinguish latent TB from active TB?
The two syndromes are treated completely differently. Latent TB is non-infectious and does not require treatment to prevent progression of disease or transmission to others, but instead to prevent future reactivation. Active TB is infectious and needs to be treated to prevent spread of TB to others. The medications, doses and duration of therapy to treat these syndromes are also different from each other.
A. Clinical symptoms
fevers/chills, night sweats, weight loss, SOB and/or cough
depending on site of TB disease, can have extrapulmonary symptoms (GI, CNS, spine, etc)
subacute to chronic onset of symptoms (typically > several weeks)
will typically have active pulmonary abnormalities seen on imaging (this can be any type of abnormality – infiltrates, cavitary lesions, effusions, or solitary nodules)
although the most common cause of apical lung scarring is prior TB infection, lung abnormalities DO NOT have to be in the apices of the lungs (they can be anywhere)
Latent TB (make diagnosis ONLY after you have excluded active TB)
A. Clinical symptoms
the patient is asymptomatic (= NO symptoms of active TB)
there is no active lung abnormality on chest imaging
(calcified granulomas/nodules or anything that is deemed old, healed scarring is excluded)
*If there are any signs suggestive of active TB, then the patient should undergo active TB evaluation (discussed below). If there is no evidence of active TB, then treatment can be based on latent TB diagnostics (discussed below).
Step 3: Evaluating for TB – diagnostic tests
A. Active TB tests (pulmonary TB)
obtain 2-3 sputum samples, ideally at least 8 hours apart, may require sputum induction if patient is not able to cough up sputum.
one ideally should be in the morning (highest burden of TB in the morning due to pooling of secretions overnight)
obtaining a bronchoscopy sample only counts for one sample
send a nucleic acid amplification test (NAAT) on the 1st sputum sample
1. AFB smear – fluorochrome stain of the clinical specimen
sensitivity = 67.5% (95% CI, 60.6 to 73.9)8
specificity = 97.5% (95% CI, 97.0 to 97.9)8
2. AFB culture – the gold standard test for tuberculosis diagnosis
can take up to 6 weeks to grow for solid culture versus ~ 2 weeks for liquid culture
3. PCR = NAAT (nucleic acid amplification test) – this is a DNA test using amplification methods
GeneXpert MTB/RIF assay is a brand test that combines the NAAT with rapid test for rifampin resistance sensitivity and specificity are high in pulmonary tuberculosis but is lower when used on specimens other than sputum.
sensitivity: 98% (for smear-positive, culture-positive specimens in HIV-negative patients)9
this test can be run on both AFB smear negative and positive specimens (although sensitivity is lower on AFB smear negative specimens)
more specific than the smear because it tests directly for tuberculosis genes, whereas positive AFB smears can be due to non-tuberculous mycobacteria or other acid-fast staining bacteria (i.e. Nocardia)
positive result → TB diagnosis negative result → does not rule out TB
B. Latent TB tests
1. Tuberculin Skin Test (TST) = Purified Protein Derivative (PPD)
intradermal injection of tuberculin material (many different materials available)
causes a delayed-type hypersensitivity response in individuals whose immune system has been exposed to TB before
positive test = induration at the injection site within 48-72 hours
negative test = no induration
Threshold for treatment
TB, tuberculosis; CXR, chest X-ray; HIV, human immunodeficiency virus; IBW, ideal body weight
*individuals who have received the BCG vaccine in the past may also test positive with this test since their immune systems have been exposed to TB via the vaccine (although immunity tends to wane within 10 years if vaccine is administered in infancy)
2. Interferon Gamma Release Assay (IGRA) = QuantiFERON-TB Gold or Plus OR T-SPOT.TB
blood test for detection of cell-mediated immune response to TB antigen
not affected by BCG vaccine or BCG treatment
80-90% sensitivity, >95% specificity (sensitivity is diminished in immunocompromised hosts)5
the QuantiFERON-TB Gold test is made up of 3 tubes:
negative control (everyone should not react)
positive control (everyone should react), and the
TB antigen that is recognized by CD4 cells
**QuantGold-PLUS (a new test) has added a 4th tube with TB antigen that binds to CD8 cells thereby increasing sensitivity of the test12
positive test → patient’s blood reacted to the TB antigen and positive control but not the negative control
negative test → patient’s blood did not react to the TB antigen but did react to the positive control
indeterminate test → patient’s blood did not react to the positive control so test is invalid (this typically happens when the patient is immunocompromised and cannot mount an immune response to the positive control and thus would not react to the TB antigen either – even if they were exposed to TB)
*Indeterminate result DOES NOT mean it is in the middle between negative and positive. It means the test cannot provide a valid result.
*all latent diagnostic tests can cross-react in individuals infected with non-tuberculous mycobacteria (TST more so than the IGRA)
*Neither test is 100% sensitive and specific – if the patient has high pre-test probability for TB exposure and for future TB reactivation, ID physicians will sometimes treat for latent TB despite the negative tests
Step 4: Treating TB
Treatment is complex and both choice of medication and duration depends on a variety of clinical and microbiological factors. Here is a basic overview of the difference in treatment between latent and active TB.
A. Latent TB (CDC)
*This is a useful calculator to determine the risks and benefits of TB reactivation vs. side effects from treatment in an individual patient.
a) Isoniazid – daily for 6 to 9 months
b) Rifampin – daily for 4 months
c) Rifapentine and isoniazid – weekly for 3 months
B. Active TB — depends on susceptibility of bacteria and clinical syndrome — RIPE therapy is the standard first-line therapy for fully-susceptible pulmonary TB infection with 2 months of all four drugs followed by 4 months of rifampin and isoniazid.
R = rifampin
I = isoniazid
P = pyrazinamide
E = ethambutol
*Ethambutol can be discontinued if drug susceptibility testing confirms a fully susceptible strain
*Patients with extensive disease e.g. cavitation or who remain smear and/or culture positive at 2 months may require a longer duration of therapy.
Don’t forget to:
give daily Vitamin B6 with isoniazid to prevent peripheral neuropathy
get baseline eye exam when starting ethambutol to enable monitoring for optic neuritis, particularly in patients with abnormal renal function
evaluate for other co-morbidities such as HIV, hepatitis B or C, diabetes or substance use
1. Global Tuberculosis Report 2018: Executive Summary. World Health Organization. Published Sept 2018. Accessed Mar 10, 201
2. Chida N, Brown C, Mathad J, et al. Internal Medicine Residents’ Knowlesge and Practice of Pulmonary Tuberculosis Diagnosis. OFID. 2018; 5(7).
3. Tuberculosis (TB). Centers for Disease Control and Prevention. Available from: https://www.cdc.gov/tb. Accessed Feb 13, 2019.
4. US Preventive Services Task Force. Screening for Latent Tuberculosis Infection in Adults. US Preventive Services Task Force Recommendation Statement. JAMA. 2016; 316(9):962-969. doi:10.1001/jama.2016.11046
5. Lewinsohn DM, Leonard MK, LoBue PA, et al. Official American Thoracic Society/Infectious Disease Society of America/Centers for Disease Control and Prevention Clinical Practice Guidelines: Diagnosis of Tuberculosis in Adults and Children. Clin Infect Dis. 2017; 64(2):111-115. doi: 10.1093/cid/ciw778
6. Horsburgh CR. Priorities for the Treatment of Latent Tuberculosis Infection in the United States. N Engl J Med. 2004; 350:2060-2067. DOI: 10.1056/NEJMsa031667
7. Pai M, Behr MA, Dowdy D, et al. Primer: Tuberculosis. Nature Reviews. 2016; 2:1-23.
8. Mathew P, Yen-Hong K, Vazirani B, Eng RHK, and Weinstein MP. Are Three Sputum Acid-Fast Bacillus Smears Necessary for Discontinuing Tuberculosis Isolation? J Clin Microbiol. 2002; 40(9):3482-3484. doi: 10.1128/JCM.40.9.3482-3484.2002
9. Steingart KR, Schiller I, Horne DJ, Pai M, Boehme CC, and Dendukuri N. Xpert® MTB/RIF assay for pulmonary tuberculosis and rifampicin resistance in adults. Cochrane Database Syst Rev. 2014 Jan 21;(1):CD009593. doi: 10.1002/14651858.CD009593.pub3.
10. Zeka AN, Tasbakan S, and Cavusoglu C. Evaluation of the GeneXpert MTB/RIF Assay for Rapid Diagnosis of Tuberculosis and Detection of Rifampin Resistance in Pulmonary and Extrapulmonary Specimens. 2011; 49(12):4138-4141. doi:10.1128/JCM.05434-11.
This post is co-written with the guest writer Ahmed Abdul Azim, MD.
Not all fevers are caused by infections.
It is important that every patient presenting with fever is evaluated for an infection….. but what do you do when no infection is found?
Why are non-infectious causes of fever important to know?
If a patient is treated for a presumed infectious fever when they don’t have an infection:
there is a delay in identifying the correct diagnosis
they are exposed to prolonged courses of unnecessary antibiotics
Definition of fever
Fever = 38.3°C (101°F) or above1
Pyrogenic agents = substances that can induce a fever.
a) Exogenous pyrogens – external substances that activate our immune system to induce a fever (ex. microbial toxins)
b) Endogenous pyrogens – cytokines that induce fever in our body
(ex. IL-1, IL-6, tumor necrosis factor, IFN-α, ciliary neutrotrophic factor, and likely others)
Non-infectious causes of fever:
1. Rheumatologic/autoimmune – activation of immune system that stimulates the production of pyrogenic cytokines
– the cause of ~30% of fevers of unknown origin
a) Adult-onset Still’s disease – younger patients, daily fevers >39°C, rash, arthritis
b) Giant cell arteritis – older patients, vision changes, jaw claudication
c) Others – polyarteritis nodosa, Takayasu’s arteritis, granulomatosis with polyangiitis, etc.
a) Lymphomas and leukemias – most common; seen in high burden of disease
b) Myelodysplastic syndromes
c) Renal cell carcinoma – ~20% of cases present with fevers
d) Hepatocellular carcinoma or liver metastases
e) Atrial myxomas
3. Drug-induced fever – 3-5% of drug-related adverse reaction in hospitalized patients include fevers6 – typically occurs 7-10 days after drug initiation, but can be as soon as 24 hours and as far away as a few years from drug initiation7 – patients typically appear “inappropriately” well
– eosinophilia (>500/mm3) occurs in 20-25% of patients with drug-induced fevers10 – PATHOPHYSIOLOGY:
a) Hypersensitivity reaction – due to activation of T cell immune response by drug, its metabolite, or the formation of an immune complex
– typically occurs ~3-10 days after drug exposure
– typically resolves 72-96 hours after discontinuation of drug (but can be more delayed)
– symptoms will recur immediately upon rechallenge
1) Antimicrobials – most common cause of drug fever
– minocycline, beta-lactams (penicillin-based > cephalosporins10), sulfonamides, nitrofurantoin
2) Anticonvulsants – carbamazepine, phenytoin, phenobarbital
– DRESS syndrome – a severe type of drug hypersensitivity reaction
(typically occurs 2-6 weeks after drug exposure)
b) Administration-related – typically last <48 hours
1) Vaccines – stimulation of the immune system → release of pyrogenic cytokines
2) Amphotericin B – exogenous pyrogenic agents
c) Pharmacologic action of the drug– transient fever; self-resolving
1) Anti-neoplastic agents – cause severe and rapid tumor cell lysis → release of endogenous pyrogenic agents → inflammatory response (fever)
2) Antimicrobials – cause rapid death of microbes → microbial cell lysis → release of exogenous pyrogenic substances → inflammatory response (fever)
– ex. Jarisch-Herxeimer reaction in syphilis treatment with penicillin
d) Altered thermoregulation – disturbance of the central hypothalamic thermoregulation function and/or increased heat production
1) Transfusion of blood cells – RBCs, platelets, WBCs
2) Central fevers – fevers due to central thermodysregulation due to CNS damage
– more common with CNS hemorrhage and brain tumors11 – fever onset within 72 hours of sustaining CNS hemorrhage
3) Thromboembolism – typically <102°F
4) Endocrine – thyroid storm; adrenal insufficiency
5) Pulmonary – ARDS, aspiration pneumonitis, cryptogenic organizing pneumonia
6) Intra-abdominal – acute pancreatitis, cholecystitis, mesenteric ischemia
*Non-infectious causes of fevers are diagnoses of exclusion. A patient MUST have an appropriate workup for infectious causes prior to considering any of the non-infectious causes of fever.
*A lot of these diagnoses need to be made based on clinical symptoms and signs and requires a high degree of suspicion.
*Fever is a sign of an underlying inflammatory process. DO NOT TREAT THE FEVER — TREAT THE UNDERLYING CAUSE.
O’Grady NP, Barie PS, Bartlett JG, et al. Guidelines for evaluation of new fever in critically ill adult patients: 2008 update from the American College of Critical Care Medicine and the Infectious Diseases Society of America. Crit Care Med. 2008; 36(4):1330-1349.
Dekker AR, Verheij TJ, and van der Velden AW. Inappropriate Antibiotic Prescription for Respiratory Tract Indications: Most Prominent in Adult Patients. Family Practice. 2015; 32(4):401-407.
Mackowiak PA, Wasserman SS, and Levine MM. A Critical Appraisal of 98.6°F, the Upper Limit of the Normal Body Temperature, and Other Legacies of Carl Reinhold August Wunderlich. JAMA. 1992; 268(12):1578-1580.
Obermeyer Z, Samra JK, and Mullainathan S. Individual Differences in Normal Body Temperature: Longitudinal Big Data Analysis of Patient Records. BMJ. 2017; 359:j5468.
Westbrook A, Pettila V, Nichol A, et al. Transfusion Practice and Guidelines in Australian and New Zealand Intensive Care Units. Intensive Care Med. 2010; 36(7):1138-1146.
Lipsky, BA and Hirschmann JV. Drug Fever. JAMA. 1981; 245(8):851-854.
Mackowiak, PA. Southwestern Internal Medicine Conference: Drug Fever: Mechanisms, Maxims and Misconceptions. Am J Med Sci. 1987; 294(4):275-286.
Patel, RA and Gallagher JC. Drug fever. Pharmacotherapy. 2010; 30(1):57-69.
Johnson DH and Cunha BA. Drug fever. Infect Dis Clin North Am. 1996; 10(1):85-91.
Oizumi K, Onuma K, Watanabe A, et al. Clinical Study of Drug Fever Induced by Parenteral Administration of Antibiotics. Tohoku J Exp Med. 1989; 159(1): 45-56.
Hocker SE, Tian L, Li G, et al. Indicators of Central Fever in the Neurologic Intensive Care Unit. JAMA Neurology. 2013; 70(12):1499-1504.
Porat R and Dinarello CA. Pathophysiology and treatment of fever in adults. In Baron EL, ed. UpToDate. Waltham, Mass.: UpToDate, 2018. [https://www.uptodate.com/contents/pathophysiology-and-treatment-of-fever-in-adults]. Accessed Dec 26, 2018.
Often, the focus of medical education is on clinical diagnosis and management of disease. But what about prevention? Prevention is key. Here are some ways for both the patient and healthcare provider to prevent further infections:
Reduce transmission as much as possible
Wash hands with soap and water after leaving the room of a patient with active C. difficile infection (CDI) OR use an alcohol-based hand sanitizer if a sink is not available
Advocate healthcare facilities to:
place sinks nearby patient rooms
consider sink placement in the future construction of healthcare facilities
Educate your patients and those who live with them to:
wash their hands well after using the toilet
have infected individuals use separate toilets and toilet accessories during treatment, if possible
Avoid unnecessary antibiotic use
Avoid prescribing an antibiotic if low likelihood of bacterial infection
Narrow broad-spectrum antibiotics as soon as possible
Discontinue antibiotics as soon as possible
Consider prophylactic PO vancomycin for patients with history of recurrent C. difficile infection
A retrospective review demonstrated that administration of PO vancomycin 125mg twice a day was associated with a lower incidence of recurrent C. difficile infection (4.2% vs. 26.6%, p<0.001)3
Educate yourself on the risks and benefits of probiotic use and be able to relay that information to your patients if they ask.
Some studies show no reduction in incidence of C. difficile infection with probiotic use6,7
Other studies (including a Cochrane review) show significant reduction in C. difficile infection incidence with probiotic use8,9,10,11
Studies have demonstrated that probiotics are more likely to reduce C. difficile infection incidence:
in patients with a baseline risk of C. difficile infection > 5%8,9
when probiotics are administered at higher doses10
when the probiotic consists of multiple strains10
when probiotics were administered within 2 days of antibiotic initiation11
This is the IDSA Clinical Practice Guidelines for C. difficile infection statement on probiotics: “There are insufficient data at this time to recommend administration of probiotics for primary prevention of CDI outside of clinical trials (no recommendation).” The guidelines cite the bias towards probiotics in many trials that enrolled mostly patients at very high risk of C.difficile infection and the potential for probiotics to cause harm by introducing new infections to hospitalized patients.
Any prevention strategies I didn’t mention? What do you think is the most effective prevention strategy? I would love to hear your thoughts!
McDonald LC, Gerding DN, Johnson S, et al. Clinical Practice Guidelines for Clostridium difficile Infection in Adults and Children: 2017 Update by the Infectious Diseases Society of America (IDSA) and Society for Healthcare Epidemiology of America (SHEA). Clin Infect Dis. 2018; 66(7):1-48.
Jorgensen JH, Pfaller MA, Carroll KC, et al. Manual of Clinical Microbiology, Eleventh Edition.
Van Hise NW, Bryant AM, Hennessey EK, et al. Efficacy of Oral Vancomycin in Preventing Recurrent Clostridium difficile Infection in Patients Treated With Systemic Antimicrobial Agents. Clin Infect Dis. 2016; 63(5):651-653.
Kelly CP, Lamont JT, and Bakken JS. Clostridium difficile infection in adults: Treatment and prevention. In Baron EL, ed. UpToDate. Waltham, Mass.: UpToDate, 2018. [https://www.uptodate.com/contents/clostridium-difficile-infection-in-adults-treatment-and-prevention]. Accessed May 25, 2018.
Davidson LE and Hibberd PL. Clostridioides difficile and probiotics. In Baron EL, ed. UpToDate. Waltham, Mass.: UpToDate, 2018. [https://www.uptodate.com/contents/clostridioides-formerly-clostridium-difficile-and-probiotics]. Accessed Nov 13, 2018.
Allen SJ, Wareham K, Wang D, Bradley C, Hutchings H, Harris W, et al. Lactobacilli and bifidobacteria in the prevention of antibiotic-associated diarrhoea and Clostridium difficile diarrhoea in older inpatients (PLACIDE): a randomised, double-blind, placebo-controlled, multicentre trial. Lancet. 2013; 382(9900): 1249-57.
Ehrhardt S, Guo N, Hinz R, Schoppen S, May J, Reiser M, et al. Saccharomyces boulardii to Prevent Antibiotic-Associated Diarrhea: A Randomized, Double-Masked, Placebo-Controlled Trial. Open Forum Infect Dis. 2016; 3(1):ofw011.
Goldenberg JZ, Yap C, Lytvyn L, Lo CK, Beardsley J, Mertz D, et al. Probiotics for the prevention of Clostridium difficile-associated diarrhea in adults and children. Cochrane Database Syst Rev. 2017; 12:CD006095.
Johnston BC, Lytvyn L, Lo CK, Allen SJ, Wang D, Szajewska H, et al. Microbial Preparations (Probiotics) for the Prevention of Clostridium difficile Infection in Adults and Children: An Individual Patient Data Meta-analysis of 6,851 Participants. Infect Control Hosp Epidemiol. 2018; 39(7): 771-781.
Johnston BC, Ma SSY, Goldenberg JZ, Thorlung K, Vandvik PO, Loeb M, et al. Probiotics for the Prevention of Clostridium difficile-Associated Diarrhea. Ann of Intern Med. 2012; 157:878-888
Shen NT, Maw A, Tmanova LL, Pino A, Ancy K, Crawford CV, et al. Timely Use of Probiotics in Hospitalized Adults Prevents Clostridium difficle Infection: A Systematic Review With Meta-Regression Analysis. Gastroenterology. 2017; 152(8): 1889-1900.
During the first week of October, the Infectious Diseases Society of America (IDSA) hosted its’ annual Infectious Diseases conference (IDWeek) in San Francisco, California.
There are a variety of reviews of the conference on the internet (the most famous being the Mini Really Rapid Review by Dr. Paul Sax) but I want to highlight the studies that are pertinent to physicians in other specialties outside of ID.
Two major studies highlighted the ongoing pressures and scope for over-prescription of antibiotics and need for antimicrobial stewardship
In one study, 66.1% of patients were prescribed antibiotics for respiratory tract infections and antibiotic prescribing was associated with higher patient satisfaction. Given that most respiratory tract infections are viral, 66% is a lot!
Another study showed that 20% of antibiotics are prescribed without an in-person visit. Of all the 509,534 antibiotic prescriptions, 46% were not associated with an infection-related diagnosis. This highlights the need for better provider and patient education in antibiotic stewardship.
IV drug use may be an independent risk factor for candidemia.
This study showed an increasing incidence of candidemia and higher numbers of patients with candidemia who are persons who inject drugs without other risk factors. Something to keep in mind when you see patients who inject drugs in your hospital.
And for those of you in San Francisco, watch out for these microbes:
A precursor to calcitonin and thus consistently produced by the thyroid gland C cells
An acute phase reactant (and can be used as a marker of a bacterial infection in the body)
procalcitonin levels parallel severity of the infection/systemic inflammation
increases are detectable ~4 hours after exposure to endotoxin and peaks at 12-48 hours
Why isn’t procalcitonin produced in response to a
It is hypothesized that tumor necrosis factor (TNF) is essential to the synthesis of procalcitonin. When the body is exposed to a viral infection, the virus induces production of interferons which in turn suppresses TNF expression.
Why do we need it?
Studies have shown that up to 50% of antimicrobial use in the inpatient setting is unnecessary. Part of the reason is that we don’t always know who has a bacterial infection and who does not.
A blood test that can help differentiate types of infection and help shorten the duration of unnecessary antibiotics would be extremely helpful to physicians and beneficial to patients.
How does it work?
Procalcitonin level is measured in the blood with a blood-draw
Can be run from EDTA (purple) or heparin (green) tubes but NOT citrate-containing tubes
Levels correlate with severity of the infection/systemic inflammation
When/how do you use it?
The data on how best to use procalcitonin and when to use it remains controversial, and each institution may have their own guidelines on how best to utilize it.
Studies demonstrate that procalcitonin can be used to determine:
Whether to initiate antibiotic therapy
Duration of antibiotic therapy
The TWO scenarios with the most literature suggesting procalcitonin use is helpful are in guiding duration of antibiotic therapy in:
Lower Respiratory Tract Infections (LRTI)
Summary of some major trials in each area
Lower respiratory tract infections A)Schuetz et al. 2017 (Cochrane Systematic Review) – Cochrane systematic review of RCTs to evaluate procalcitonin in guiding initiation or discontinuation of antibiotics
– moderate to high quality evidence; 6708 participants, 26 trials Primary outcomes: 1) all-cause mortality, 2) treatment failure at 30 days All-cause mortality:6% vs. 10% (controls); p-value = 0.037 Treatment failure: no significant difference (23-24% in both groups) Secondary outcomes: 1) antibiotic use, 2) antibiotic-related side effects,
3) Hospital Length of Stay (LoS) # of antibiotic days: 2.4 day reduction in antibiotic exposure (5.7 vs 8.1 days) Side effects of antibiotics: 16.3% vs. 22.1% (control), (p-value <0.001) LoS in hospital and ICU: no difference Summary: improved mortality and increase in antibiotic-free days between the two groups B)Huang et al. 2018 (ProACT study) – Multicenter RCT, 1656 patients enrolled
– Procalcitonin was checked in the ED and followed during hospital course if patient was admitted
– There was no difference in # of antibiotic exposure days over 30 days, rates of adverse events, or hospital length of stay (LoS)
– There was no difference even when stratified by diagnosis of acute bronchitis, COPD, CAP, and other LRTI. Summary: no change in # of antibiotic-exposure days or adverse effects between the two groups
Severe sepsis/shock A) DeJong et al. 2016 – Multicenter RCT in hospitals, 1575 enrolled Mortality: 20% vs. 25% (control) (p=0.0122) Median antibiotic duration: 7.5 days vs. 9.3 days (control); p-value <0.0001
– There was a slightly higher risk of reinfection in the procalcitonin group (5% vs. 2.9%, p=0.0492)
– No difference between ICU and hospital LoS between groups Summary: Use of procalcitonin reduced mortality and # of antibiotic exposure days but not LoS B) Andriolo et al. 2017 (Cochrane Systematic Review) – 10 trials, 1215 participants, low quality evidence
– No significant differences in mortality at 28 days, ICU discharge, or hospital stay
– Procalcitonin group had a mean 1.28 day less of antibiotic exposure than control group Summary: Use of pro-calcitonin reduced # antibiotic exposure days but not mortality C) Wirz et al. 2018
– Meta-analysis of RCTs
– 4482 patients overall Mortality: lower in the procalcitonin group (21.1% vs. 23.7%, p=0.03) # of antibiotic days: lower in procalcitonin group (9.3 vs. 10.4d, p<0.001) Summary: Use of procalcitonin reduces mortality and # of antibiotic exposure days
*It’s important to remember that all these trials have varying adherence to the protocols, various study populations, and centers with varying practice patterns that all affect the results of the studies.
**Procalcitonin should NOT typically be used for determine whether to initiate antibiotics in pneumonia or sepsis given the high risk of a poor outcome with a false negative result.
How to use it
Obtain procalcitonin at time of diagnosis and repeat every 1-2days.
Stop antibiotics when procalcitonin level is <0.1-0.5ng/ml or decreased by at least 50-90% from peak value
*Procalcitonin can also be used when it is unclear whether a patient has a bacterial infection or not to help guide further management.
Other potential uses of PCT
Presence of bacterial infection in patients with COPD exacerbations, heart failure exacerbations, or bronchitis
Aspiration pneumonia vs. pneumonitis
Fevers of unknown origin
UTI therapy duration
Bacterial vs. viral meningitis
Lower limb swelling
(distinguishing between stasis dermatitis vs. thrombosis vs. cellulitis)
And many others
short half-life (25-30 hours)
dialyzed; in ESRD, levels tend to be higher prior to dialysis than after dialysis
peak levels tend to correlate with severity of infection
if inflammation is resolving, levels should decrease by ~50% every 1-2 days.
⇒mild elevation = 0.15-2ng/mL
a) localized bacterial infection
b) ESRD without recent hemodialysis
c) noninfectious systemic inflammatory response
⇒significant elevation > 2ng/mL
a) bacterial sepsis or severe localized bacterial infection
b) severe non-infectious inflammatory stimuli (major burn, severe trauma, acute multisystem organ failure, bowel ischemia, stroke, major abdominal or cardiothoracic surgery)
c) false positive from malignancy
Pulmonary TB and some other non-tuberculosis mycobacterial infections
Severe systemic stress (trauma, severe burns, surgery, cardiac arrest/shock, Addisonian crisis, pancreatitis, intracranial hemorrhage)
*possibly due to gut translocation of LPS
if drawn too early in infection (typically rises within 2-5 hours)
Procalcitonin levels are NOT impaired in immunocompromised hosts (ICH) ⇒however, little information is known regarding use of procalcitonin in this patient population
⇒these patients have a low threshold for antibiotic initiation and prolonged duration thus no recommendations can be made to use procalcitonin to guide management in ICH at this time
⇒not enough data exists yet to support routine clinical use.
Not enough data exists yet to support routine clinical use in surgical patients surgical patients may have a higher baseline procalcitonin level after certain surgeries
Procalcitonin can be thought of similarly to B-natriuretic peptide (BNP) and as a more sensitive C-reactive protein (CRP). It can be used within a broader clinical context to support a diagnosis or decision regarding antibiotics and is useful in RULING OUT bacterial causes.
Use of procalcitonin and its algorithms should NOT override or replace clinical judgment.
Serial measurements and trends are more helpful than one isolated value.
A rising procalcitonin level is not, by itself, an indication to broaden antibiotic therapy.
In order to use procalcitonin effectively, its essential to understand which pathogens induce elevations in procalcitonin.
The use of procalcitonin has been most studied in LRTI and sepsis. The utility of procalcitonin in other situations remains unknown.
Andriolo BN, Andriolo RB, Salomão R, and Atallah ÁN. Effectiveness and safety of procalcitonin evaluation for reducing mortality in adults with sepsis, severe sepsis or septic shock. Cochrane Database Syst Rev. 2017;1:CD010959.
Gilbert DN. Use of Plasma Procalcitonin levels as an adjunct to clinical microbiology. J Clin Microbiol. 2010; 48(7):2325-2329. doi: 10.1128/JCM.00655-10
de Jong E, van Oers JA, Beishuizen A, Vos P, Vermeijden WJ, Haas LE, et al. Efficacy and safety of procalcitonin guidance in reducing the duration of antibiotic treatment in critically ill patients: a randomised, controlled, open-label trial. Lancet Infect Dis. 2016; 16:819-827. doi: http://dx.doi.org/10.1016/S1473-3099(16)00053-0
Jensen JU, Heslet L, Jensen TH, Espersen K, Steffensen P, and Tvede M. Procalcitonin increase in early identification of critically ill patients at high risk of mortality. Crit Care Med. 2006; 34:2596-2602.
Riedel S, Melendez JH, An AT, Rosenbaum JE, and Zenilman JM. Procalcitonin as a marker for the detection of bacteremia and sepsis in the emergency department. Am J Clin Pathol. 2011; 135(2):182-189. doi: 10.1309/AJCP1MFYINQLECV2.
Schuetz P, Wirz Y, Sager R, Christ-Crain M, Stolz D, Tamm M, et al. Procalcitonin to initiate or discontinue antibiotics in acute respiratory tract infections. Cochrane Database Syst Rev. 2017; 10:CD007498. doi: 10.1002/14651858.CD007498.pub3
Huang DT, Yealy DM, Filbin MR, Brown AM, Chang CCH, Doi Y, et al. Procalcitonin-Guided Use of Antibiotics for Lower Respiratory Tract Infection. NEJM. 2018; 379:236-49. doi: 10.1056/NEJMoa1802670.
Wirz Y, Meier MA, Bouadma L, Luyt CE, Wolff M, Chastre J, et al. Effect of procalcitonin-guided antibiotic treatment on clinical outcomes in intensive care unit patients with infection and sepsis patients: a patient-level meta-analysis of randomized trials. Critical Care. 2018; 22:191. https://doi.org/10.1186/s13054-018-2125-7.
1. Yeast in the sputum does not always need treatment.
We often see yeast pop up in sputum cultures and BAL cultures in ICU patients. However, yeast in hospitalized patients is typically Candida species, which are NOT typical pulmonary pathogens. Candida pneumonia is rare. In a recent study that looked at how often yeast isolated from sputum/BAL culture in ICU patients truly are reflective of Candida pneumonia, they found that 5/701 samples were consistent with Candida pneumonia (0.7%). 3/5 patients had severe gastric contents aspiration and 4/5 were immunocompromised.1
What does this mean? Unless the patient recently had significant aspiration or is immunocompromised, Candida spp. in the sputum is unlikely to be a true pathogen.
Other potential yeasts can include Cryptococcus spp., Histoplasma capsulatum, Blastomycosis spp., Coccidioides spp., and Paracoccidioides spp. These can represent true clinical infections. Treatment for these infections is different from Candida spp. and risk should be assessed given the patient’s clinical context.
2. It’s all about “source control”.
This means that if the area of infection can be physically removed or debrided, it should be done to optimize the chance of cure. This can also help increase diagnostic yield for targeted antibiotic therapy. Examples:
If there is an abscess, it should be drained, if possible.
If there is an infected foreign body, it should be removed, if possible.
If there is infected bone, it should be debrided/removed, if possible.
The STOP-IT trial in 2015 showed that in patients with intra-abdominal abscesses who received adequate source control (drainage of abscess or surgical resection), 3-5 days of antibiotics post-source control was non-inferior to 8-10 days of antibiotics after source control.2
There are obviously times when source control is not possible, too risky, or may cause more harm than benefit. However, anytime a patient has an infection, source control should be considered in the initial management strategy.
3. Do not treat asymptomatic bacteriuria and do not send urine cultures on asymptomatic patients.
The urogenital tract is not a sterile area and bacteria are often found that are not causing any symptoms or harm to the patient.
Antibiotics that are started for asymptomatic bacteriuria can cause harm.
If a patient has a urinary catheter, replace urinary catheter and resend a urine culture.
Pyuria in asymptomatic bacteriuria does not require treatment3.
The 2 times to treat asymptomatic bacteriuria:
Patients who are about to undergo a urologic procedure
A Cochrane review published in 2015 evaluated 9 randomized-controlled-trials (and a total of 1614 non-pregnant adults) who looked at antibiotic treatment vs. placebo for asymptomatic bacteriuria, and demonstrated that there was no difference in development of symptomatic urinary tract infections, UTI complications, or death between the two groups. The treatment group had a 3.77 increased risk of antibiotic side effects.4
4. Beta-D-glucan results need to be taken in the context of the patient’s clinical picture.
Not all fungal infections cause elevated beta-D-glucan and not all elevated beta-D-glucan levels indicate a fungal infection.
Initial studies that looked at beta-D-glucan test characteristics were done in immunocompromised patients. In that group, the test performed well, with sensitivity ranging 64-95% and specificity ranging from 92-95% (variation depending on prevalence and test level cutoff for positivity).5-7
However, in the non-immunocompromised population in the intensive care units, the test has not shown to have the same specificity. The sensitivity remains high in the 80%-90% range while specificity drops as low as 38% in non-neutropenic patients with known candida colonization.8-10
A bronchial (BAL) specimen can count as one sputum sample.11
In the US from 2011-2013, only 46% of patients with TB had a positive AFB smear.
⇒ Three negative sputum AFB smears does not “rule out” TB. The patient can still have TB, but the probability of TB is lower and they are less likely to be infectious if all three smears are negative.11,12,13
Sawyer RG, Claridge JA, Nathens AB, et al. Trial of Short-Course Antimicrobial Therapy for Intraabdominal Infection. NEJM. 2015; 372:1996-2005. doi:10.1056/NEJMoa1411162
Nicolle LE, Bradley S, Colgan R, et al. Infectious Diseases Society of America Guidelines for the Diagnosis and Treatment of Asymptomatic Bacteriuria in Adults. CID. 2005; 40: 643-654.
Trestioreanu, AZ, Lador A, Sauerbrun-Cutler M, and Leibovici, L. Antibiotics for asymptomatic bacteriuria. The Cochrane Database of Systematic Reviews. 2015. doi:10.1002/14651858.CD009534.pub2
Odabasi Z, Mattiuzzi G, Estey E, et al. β- d -Glucan as a Diagnostic Adjunct for Invasive Fungal Infections: Validation, Cutoff Development, and Performance in Patients with Acute Myelogenous Leukemia and Myelodysplastic Syndrome. Clin Infect Dis. 2004; 2(15):199-205. doi:https://doi.org/10.1086/421944
Ostrosky-Zeichner L, Alexander BD, Kett DH, et al. Multicenter Clinical Evaluation of the (1→3) β-D-Glucan Assay as an Aid to Diagnosis of Fungal Infections in Humans. Clin Infect Dis. 2005; 41(5): 654-659. doi:https://doi.org/10.1086/432470
Obayashi T, Negishi K, Suzuki T, and Funata N. Reappraisal of the serum (1–>3)-beta-D-glucan assay for the diagnosis of invasive fungal infections–a study based on autopsy cases from 6 years. Clin Infect Dis. 2008;46(12):1864-70. doi:10.1086/588295
Mohr JF, Sims C, Paetznick V, et al. Prospective survey of (1à3)-beta-D-glucan and its relationshop to invasive candidiasis in the surgical intensive care unit setting. J Clin Microbio. 2011; 49(10):58-61. doi:10.1128/JCM.01240-10
Liew YX, Teo J, Ai-Ling Too I, et al. Candida Surveillance in Surgical Intensive Care Unit (SICU) in a Tertiary Institution. BMC Infect Dis. 2015; 15(256):1-8. doi:10.1186/s12879-015-0997-6
Lo Cascio G, Koncan R, Stringari G, et al. Interference of confounding factors on the use of (1,3)-beta-D-glucan in the diagnosis of invasive candidiasis in the intensive care unit. Eur J Clin Microbiol Infect Dis. 2015; 34(2):357-365. doi:10.1007/s10096-014-2239-z
Lewinsohn DM, Leonard MK, LoBue PA, Cohn DL, Daley CL et al. Official American Thoracic Society/Infectious Disease Society of America/Centers for Disease Control and Prevention Clinical Practice Guidelines: Diagnosis of Tuberculosis in Adults and Children. 2017; 64(2):111-115. doi: 10.1093/cid/ciw778
Mase S, Ramsay A, Ng N, Henry M, Hopewell PC, Cunningham J, Urbanczik R, Perkins M, Aziz MA, Pai M. Yield of serial sputum specimen examinations in the diagnosis of pulmonary tuberculosis: a systematic review. Int J Tuberc Lung Dis. 2007;11(5):485-95. PMID:17439669
CDC. Reported Tuberculosis in the United States, 2013. Atlanta, GA: U.S. Department of Health and Human Services, CDC, October 2014.
In light of the recently published IDSA guidelines on C. difficile, I thought I would write up a summary of the guidelines as well as provide some of the background microbiology of the organism for review.
– form spores (= dormant, non-reproductive structure that the bacteria can reduce itself to in order to survive for extended periods of time in extreme conditions)
produce toxins (toxin A and toxin B) that cause disease
animal and human feces
Mechanism of pathogenicity
*Not all strains of C. difficile are pathogenic – only the ones who produce toxins can cause C. difficile disease
Transmission occurs with ingestion of spores via the fecal-oral route ⇒ spores activate in the colon to replicating bacteria ⇒ bacteria release toxins ⇒ toxins cause breakdown of the colon cells’ cytoskeleton framework ⇒ apoptosis ⇒ breakdown of the mucosal wall ⇒ DIARRHEA!
Risk factors for acquiring C. difficile:
Exposure to healthcare facilities
Age and immunosuppression
?Gastric acid suppression (use of proton pump inhibitors or H2 receptor blockers)
— the evidence-based-medicine jury is still out on this one
symptoms can develop during antibiotic treatment or up to 6 weeks after the course of antibiotics has been finished
patients can also become infected even without exposure to antibiotics (both in the healthcare setting but also in the community setting)
carrier state = a patient who is colonized with C. difficile but is currently asymptomatic
1.Symptoms and physical exam signs:
Non-bloody, WATERY DIARRHEA (≥ 3 loose stools in 24 hours)
*occasionally patients can develop ileus with severe infection which will not result in diarrhea but rather lack of bowel movements
Fever and chills
High white blood count (occasionally precedes the diarrhea by 1-2 days)
Elevated lactate and low albumin (in fulminant cases)
Pseudomembranous colitis = inflammation of the colon causing elevated white and yellow-colored plaques to form and coalesce together to create a pseudomembrane on the colon wall that can be seen by colonoscopy.
When to test: when patient has new onset, ≥ 3 unformed stools that cannot be explained by another cause (i.e. laxative use)
Options for testing:
* C. difficile can be grown in culture, but anaerobes take a while to grow and it would not provide an answer as to whether the strain is toxigenic (i.e. produces toxin) or not, so it is not commonly used for clinical diagnostic purposes.
What it is
Toxin EIA assay
Antibody assay that detect toxins
High specificity (>84%)
Low sensitivity (31-99%)
Detects GDH (an enzyme produced by C. difficile)
High NPV (>99%)
Cannot distinguish toxigenic vs. non-toxigenic C. difficile strains
PCR method that detects toxin production gene
High NPV (>99%)
Poor specificity and PPV
*Changes depending on whom specimens are collected on (low suspicion vs. high suspicion)
Many healthcare facilities are currently doing only PCR testing. It’s highly sensitive and the results return quickly (usually within 24 hours).
The problem: this practice is yielding a lot of false positives (patients who are carriers but do not truly have an active infection) which ⇒ over-treatment ⇒ patient discomfort, potential side effects, infection control consequences for the hospital, and extra costs.
Why: This is thought to be due to the fact that a lot of tests are sent inappropriately (on patients that have diarrhea but no other evidence of infection such as leukocytosis, AKI, abdominal pain, fever, etc.)
Solution (as proposed by IDSA guidelines):
A multiple step algorithm:
GDH assay + EIA assay
GDH assay + EIA assay with NAAT as a tiebreaker
NAAT + EIA assay
We can agree to be more mindful of when we send the test (when the pre-test probability is high) and continue to use the NAAT/PCR method alone.
Bottom line: Many hospitals are switching over to the two-step testing method for multiple reasons:
behavior change is difficult to implement and sustain
provides more accurate incidence of nosocomial-acquired infections in the hospital
WHEN YOU THINK OF SENDING A C. DIFFICILE TEST, ask yourself:
Does this patient have an unexplained fever, leukocytosis, or new abdominal pain/distention, in addition to the diarrhea (or in presence of ileus)?
– if yes ⇒ send the test
If not, is there another explanation for the diarrhea?
(i.e. laxatives, new medications (especially antibiotics), part of already known illness, etc.)
– if yes ⇒ consider removing the potential cause (if possible) and re-evaluate or monitor for worsening symptoms
– if not⇒ send the test
The IDSA has a really great table to reference when choosing treatment options for your C. difficile infected patient.
***PO Metronidazole is no longer the 1st-line agent for C. diff infection treatment***
McDonald et al. CID 2018
Recurrence of C. difficile infection = reappearance of symptoms within 2-8 weeks after completion of therapy
up to 25% of patients will experience a recurrence
once patient had one recurrence, they are at higher risk for future recurrences
The MAJOR risk factor for C. difficile infection is ANTIBIOTIC EXPOSURE
⇒ DO NOT give antibiotics to those who do not truly need them
Symptoms/signs include watery diarrhea, abdominal cramping/pain, and elevated WBC and creatinine
C. difficile infection CAN cause ileus (i.e. no diarrhea)
Only send test when you have a high pre-test probability to avoid false positives
Metronidazole is NO LONGER recommended for treatment of C. difficile
Got questions? Disagree? Leave your comments below!
McDonald LC, Gerding DN, Johnson S, et al. Clinical Practice Guidelines for Clostridium difficile Infection in Adults and Children: 2017 Update by the Infectious Diseases Society of America (IDSA) and Society for Healthcare Epidemiology of America (SHEA). Clin Infect Dis. 2018. 66(7):1-48. [PMID: 29562266]
Jorgensen JH, Pfaller MA, Carroll KC, et al. Manual of Clinical Microbiology, Eleventh Edition.
Lamont JT. (2018). Clostridium difficile infection in adults: Epidemiology, microbiology, and pathophysiology. In Baron EL, ed. UpToDate. Waltham, Mass.: UpToDate, 2018. [https://www.uptodate.com/contents/clostridium-difficile-infection-in-adults-epidemiology-microbiology-and-pathophysiology]. Accessed May 25, 2018.
Lamont JT, Kelly CP, and Bakken JS. Clostridium difficile infection in adults: Clinical manifestations and diagnosis. In Baron EL, ed. UpToDate. Waltham, Mass.: UpToDate, 2018. [https://www.uptodate.com/contents/clostridium-difficile-infection-in-adults-clinical-manifestations-and-diagnosis]. Accessed May 25, 2018.
Kelly CP, Lamont JT, and Bakken JS. Clostridium difficile infection in adults: Treatment and prevention. In Baron EL, ed. UpToDate. Waltham, Mass.: UpToDate, 2018. [https://www.uptodate.com/contents/clostridium-difficile-infection-in-adults-treatment-and-prevention]. Accessed May 25, 2018.
The plan was to release new community-acquired pneumonia (CAP) guidelines shortly thereafter.
Those CAP guidelines have now been pushed back to be tentatively published in summer 2018.
This post is meant to cover some common misconceptions about the treatment of pneumonia and clinical pearls while we patiently await the release of the new guidelines.
Let’s start with the basics:
HCAP & CAP – those presenting to the hospital with pneumonia HAP & VAP – those that developed pneumonia >48 hours after admission to the hospital or mechanical ventilation, respectively.
But I thought the term HCAP was gone…
While the 2016 guidelines no longer address HCAP, HCAP as an entity has not disappeared (despite what some may tell you). It will likely be discussed in the as-of-yet unreleased CAP guidelines. But in the meantime, feel free to use the algorithm presented above for guidance.
Previous guidelines from 2005 grouped HCAP in with HAP and VAP in terms of treatment. But since then, it’s been determined that not all HCAP patients require MRSA and Pseudomonas coverage. Many can be treated as typical CAP patients.
High-risk HCAP patients =
multiple risk factors for multi-drug resistant organisms (see green-box above)
require ICU admission to justify broad spectrum antibiotic treatment.
HAP —–YESMRSA and Pseudomonas coverage —–Consider double pseudomonal coverage if patient is hemodynamically unstable —–NOatypical pneumonia pathogen coverage Ex. Vancomycin + cefepime*
VAP —–YESMRSA and Pseudomonas coverage —–Consider double pseudomonal coverage if patient is hemodynamicallyunstable —–NOatypical pneumonia pathogen coverage Ex. Vancomycin + cefepime + tobramycin*
*These are example regimens. Please reference your own institution’s pneumonia guidelines for additional information.
Duration of Treatment = 7 days!!!
* This can likely be even shorter in cases of CAP.
** From the IDSA: “There exist situations in which a shorter or longer duration of antibiotics may be indicated, depending upon the rate of improvement of clinical, radiologic, and laboratory parameters.” 2
HCAP is still an entity – but it has been separated from HAP
CAP and HCAP – pneumonia <48 hours into a hospital stay HAP and VAP – pneumonia >48 hours into a hospital stay
CAP and low risk HCAP – NO need for MRSA and Pseudomonas coverage High risk HCAP, HAP, and VAP – DO need MRSA and Pseudomonas coverage
Duration of treatment = 7 days
Mandell LA, Wunderink RG, Anzueto A, et al. Infectious Diseases Society of America/American Thoracic Society consensus guidelines on the management of community-acquired pneumonia in adults. Clin Infect Dis. 2007; 44:S27-S72
Kalil AC, Metersky ML, Klompas M, et al. Management of adults with hospital-acquired and ventilator-associated pneumonia: 2016 clinical practice guidelines by the Infectious Diseases Society of America and the American Thoracic Society. Clin Infect Dis. 2016; 63(5):e61-e111
Dinh A, Ropers J, Davido B, et al. Effectiveness of three days of beta-lactam antibiotics for hospitalized community-acquired pneumonia: a randomized non-inferiority double-blind trial [abstract]. ECCMID Madrid, Spain, April 22, 2018.
Guest author: Jeff Pearson is currently a PGY-2 infectious diseases pharmacy resident at Beth Israel Deaconess Medical Center in Boston, Massachusetts. He also serves as an adjunct faculty member at MCPHS University, lecturing and facilitating in various courses. He received his Doctor of Pharmacy from Northeastern University in 2014. His main area of interest is antimicrobial stewardship and he will be a senior pharmacist in infectious diseases at Brigham and Women’s Hospital after completing his residency year in August 2018.
Who doesn’t love to pick up random bits of information while they’re in line for their coffee or their morning signout? Here are 5 helpful pieces of information on antimicrobials to start off your day!
1.Cefepime vs. Piperacillin-tazobactam Cefepime – cephalosporin
– DOES NOT cover gut anaerobes
– DOES NOT cover Enterococcus spp. Piperacillin-tazobactam – penicillin derivative
– DOES cover gut anaerobes
– DOES cover penicillin-sensitiveEnterococcus spp.
Gut anaerobic coverage?
Yes (if susceptible)
2.Cephalosporins in general DO NOT cover Enterococcus spp.
3. Ertapenem vs. meropenem vs. imipenem vs. doripenem Ertapenem – DOES NOT cover Pseudomonas spp. Meropenem/Imipenem/Doripenem – DO cover Pseudomonas spp.
*None of the carbapenems cover MRSA
4. Ineffective antimicrobials Daptomycin – inactivated by the surfactant in the lungs
– DO NOT use daptomycin to treat lung infections
*Remember: Linezolid, Lung (you can use Linezolid for lung infections)
Echinocandins (ex. micafungin, caspofungin, anidulafungin) – do not reach therapeutic levels in the urinary tract
– DO NOT use echinocandins to treat pyelonephritis or urinary tract infections
Tigecycline – accumulates in the tissues and has low concentration levels in the bloodstream
– DO NOT use tigecycline to treat bloodstream infections
5. Bone marrow toxicity due to linezolidincreases after 2 weeks of exposure
– Avoid using linezolid for more than two weeks at a time when possible
Do you have any random facts of ID knowledge? Let me know in the comments section below!
1. Mandell, Douglas, and Bennett. Principles and practice of infectious diseases. Philadelphia, PA: Churchill Livingstone/Elsevier, c2010. 7th edition.
2. Zhanel, G.G. et al. 2007. Comparative review of the carbapenems. Drugs. 67(7):1027-1052.
3. Gerson, S.L. et al. 2002. Hematologic effects of linezolid: summary of clinical experience. Antimicrobial Agents and Chemotherapy. 46(8): 2723-2726.
4. Malani, A.N. et al. 2014. Candida urinary tract infections: treatment options. 5(2): 277-284.
5. Jeu, L. et al. 2004. Daptomycin: a cyclic lipopeptide antimicrobial agent. Clinical Therapeutics. 26(11): 1728-1757.
Peer-reviewed by Jeff Pearson, PGY-2 pharmacy resident