Tag Archives: #BDGlucan

5 things that ID fellows wish you knew

3rdtimeisthe charm

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:

  1. Pregnant patients
  2. 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

5. Send a GeneXpert© NAAT test with the first AFB smear and remember that there is no such thing as a “TB rule out”.

The current CDC/IDSA guidelines in evaluation of active pulmonary tuberculosis is to:

  • obtain 3 sputum AFB smears/cultures at least 8-24 hours apart.11
  • ideally obtain at least one smear as an early morning sample (highest concentration of mycobacteria at that time).11
  • send a GeneXpert© nucleic acid amplification test (NAAT) on the 1st sputum specimen.11
    ⇒ This test can detect tuberculosis genes as well as detect rifampin susceptibility and usually comes back quickly.
  • 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

 

 

References:

  1. Schnabel RM, Linssen, CF, Guion CF, van Mook WN, and Bergmans DC. Candida pneumonia in Intensive Care Unit? OFID. 2014;1(1) ofu026. doi:https://doi.org/10.1093/ofid/ofu026
  2. 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
  3. 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.
  4. 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
  5. 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
  6. 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
  7. 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
  8. 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
  9. 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
  10. 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
  11. 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
  12. 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
  13. CDC. Reported Tuberculosis in the United States, 2013. Atlanta, GA: U.S. Department of Health and Human Services, CDC, October 2014.