American Society for Microbiology

Five Things Physicians and Patients Should Question

Released August 5, 2020; Revised May 4, 2021, Last reviewed 2021

  1. 1

    Do not request routinely extended incubation of blood cultures in suspected endocarditis.

    Extending incubation of routine blood cultures does not increase the recovery of clinically significant pathogens causing endocarditis. Five-day incubation,
    using currently available media formulations and automated incubation and detection systems, is sufficient to recover the majority of true pathogens including HACEK organisms. Alternative methods (such as serology, molecular, targeted fungal or mycobacterial cultures, or tissue histopathology) should be utilized, when clinically indicated, for detection of rarely encountered, fastidious organisms (Bartonella, Coxiella, Mycobacterium, dimorphic fungi) not recovered using routine blood cultures. Occasional exceptions may be appropriate and should be reviewed in consultation with an infectious disease specialist.

  2. 2

    Do not routinely test >1 stool specimen per week for Clostridioides difficile by Nucleic-acid Amplification Test (NAAT).

    Repeat testing using NAAT (within 7 days) for Clostridioides difficile is not recommended when the symptoms represent a single episode of diarrheal illness. Studies have shown that repeat testing using NAAT within a seven day period yield only a 2% diagnostic yield. Exceptions should only be made in the setting of an institutional epidemic or when C. difficile infection is highly suspected with no alternative diagnosis, but for which the initial test is negative and symptoms persist or worsen.

  3. 3

    Do not order Lyme serology on patients with a primary erythema migrans lesion.

    No current diagnostic method is highly sensitive in Lyme disease patients with less than two weeks of rash or illness. Most patients with primary Lyme disease are seronegative at the time of presentation and should be treated on clinical grounds regardless of serological results. In patients with equivocal or atypical lesions, paired testing with sera collected acutely and 2–3 weeks later may be helpful.

  4. 4

    Do not order a Lyme immunoblot without a positive Lyme Enzyme immunoassay (EIA) screening test.

    The Lyme immunoblot test is designed only as a confirmatory test, so it is important not to test screen-negative samples. Some antigens on the blot react with non-Lyme antibodies, and the immunoblot can be over-interpreted in the absence of a positive screening test. Current 2-tiered serology has a sensitivity of 70%–100% and specificity >95% for disseminated Lyme disease; use of an immunoblot without a positive screening test is unwise. While the exact characteristics of current immunoblot tests used alone are not well-defined, high false positive IgM rates have been observed in patients tested without a prior EIA.

    This recommendation assumes that a patient has had the potential for contact with ticks in an endemic area.

  5. 5

    Do not order urine cultures unless patients have symptoms consistent with urinary tract infection (UTI).

    Urine cultures should only be requested on patients who have clinical signs of UTI. Routine culture of urine in asymptomatic individuals may detect asymptomatic bacteriuria (ASB) which is commonly found in certain populations. Screening for ASB has no clinical benefit and may result in harm (1, 2).

    Testing for ASB should only be pursued in specific populations such as pregnant women and individuals who are about to undergo urologic procedures that involve mucosal disruption (2).

These items are provided solely for informational purposes and are not intended as a substitute for consultation with a medical professional. Patients with any specific questions about the items on this list or their individual situation should consult their physician.
American Society of Microbiology in partnership with the Five Things Physicians and Patients Should Question

The American Society for Microbiology is the largest single life science society, composed of 30,000 scientists and health professionals. ASM’s mission is to promote and advance the microbial sciences.

ASM advances the microbial sciences through conferences, publications, certifications and educational opportunities. It enhances laboratory capacity around the globe through training and resources. It provides a network for scientists in academia, industry and clinical settings. Additionally, ASM promotes a deeper understanding of the microbial sciences to diverse audiences.

How This List Was Created

The American Society for Microbiology’s (ASM) list was developed under the leadership of the ASM’s Clinical and Public Health Microbiology Committee. The subject matter experts who identified the list and formulated the recommendations are laboratory directors at academic, commercial and public health laboratories and test utilization experts across the fields of microbiology and laboratory medicine. They worked together to identify a list of diagnostic and management decisions that have resulted in misuse of laboratory studies and resources. The five experts independently ranked the recommendations in order of priority and identified tests or procedures commonly used whose necessity should be questioned and discussed with patients. The experts formulated recommendations based on laboratory practice, evidence and an extensive review of the literature.

Five recommendations to address the most common clinical microbiology laboratory test misconceptions were written. They consist of diagnostic tests or treatments that are commonly ordered, expensive and have no evidence to illustrate its value and in some cases, may be potentially harmful to the patient. The recommendations, if instituted, would result in higher quality care, lower costs, and more effective use of our laboratory resources and personnel. The experts involved in this project are Sheldon Campbell, Marc Couturier, Omai Garner, Duane Newton, Preeti Pancholi and Linoj Samuel.

The recommendations were vetted and approved by ASM’s Clinical and Public Health Microbiology Committee.

The list has also been reviewed and approved by the ASCP Effective Test Utilization Committee.

Sources

  1. Baron EJ, Scott JD, Tompkins LS. 2005. Prolonged Incubation and Extensive Subculturing Do Not Increase Recovery of Clinically Significant Microorganisms from Standard Automated Blood Cultures. Clin Inf Dis 41:1677-80.

    Liesman RM, Pritt BS, Maleszewski JJ, Patel R. 2017. Laboratory Diagnosis of Infective Endocarditis. J Clin Micro 55:2599-2608.

  2. McDonald LC, Gerding DN, Johnson S, Bakken JS, Carroll KC, Coffin SE, Dubberke ER, Garey KW, Gould CV, Kelly C, Loo V, Shaklee Sammons J, Sandora TJ, Wilcox MH. 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 Mar 19;66(7):987-994.

    Luo RF, Banaei N. Is repeat PCR needed for diagnosis of Clostridium difficile infection? J Clin Microbiol 2010; 48:3738–41.

    Surawicz CM, Brandt LJ, Binion DG, et al. Guidelines for diagnosis, treatment, and prevention of Clostridium difficile infections. Am J Gastroenterol 2013; 108:478–98.

  3. Moore A, Nelson C, Molins C, Mead P, Schriefer M. Current Guidelines, Common Clinical Pitfalls, and Future Directions for Laboratory Diagnosis of Lyme Disease, United States. Emerg Infect Dis. 2016 Jul;22(7).

    Lantos PM, Rumbaugh J, Bockenstedt LK, Falck-Ytter YT, Aguero-Rosenfeld ME, Auwaerter PG, Baldwin K, Bannuru RR, Belani KK, Bowie WR, Branda JA, Clifford DB, DiMario FJ Jr, Halperin JJ, Krause PJ, Lavergne V, Liang MH, Meissner HC, Nigrovic LE, Nocton JJJ, Osani MC, Pruitt AA, Rips J, Rosenfeld LE, Savoy ML, Sood SK, Steere AC, Strle F, Sundel R, Tsao J, Vaysbrot EE, Wormser GP, Zemel LS. Clinical Practice Guidelines by the Infectious Diseases Society of America, American Academy of Neurology, and American College of Rheumatology: 2020 Guidelines for the Prevention, Diagnosis, and Treatment of Lyme Disease. Neurology. 2021 Feb 9;96(6):262-273.

    CDC Lyme Disease Resources: https://www.cdc.gov/lyme/index.html

    Wormser GP, Dattwyler RJ, Shapiro ED, Halperin JJ, Steere AC, Klempner MS, Krause PJ, Bakken JS, Strle F, Stanek G, Bockenstedt L, Fish D, Dumler JS, Nadelman RB. The clinical assessment, treatment, and prevention of lyme disease, human granulocytic anaplasmosis, and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America. Clin Infect Dis. 2006 Nov
    1;43(9):1089-134.

  4. Moore A, Nelson C, Molins C, Mead P, Schriefer M. Current Guidelines, Common Clinical Pitfalls, and Future Directions for Laboratory Diagnosis of Lyme Disease, United States. Emerg Infect Dis. 2016 Jul;22(7).

    Lantos PM, Rumbaugh J, Bockenstedt LK, Falck-Ytter YT, Aguero-Rosenfeld ME, Auwaerter PG, Baldwin K, Bannuru RR, Belani KK, Bowie WR, Branda JA, Clifford DB, DiMario FJ Jr, Halperin JJ, Krause PJ, Lavergne V, Liang MH, Meissner HC, Nigrovic LE, Nocton JJJ, Osani MC, Pruitt AA, Rips J, Rosenfeld LE, Savoy ML, Sood SK, Steere AC, Strle F, Sundel R, Tsao J, Vaysbrot EE, Wormser GP, Zemel LS. Clinical Practice Guidelines by the Infectious Diseases Society of America, American Academy of Neurology, and American College of Rheumatology: 2020 Guidelines for the Prevention, Diagnosis, and Treatment of Lyme Disease. Neurology. 2021 Feb 9;96(6):262-273.

    CDC Lyme Disease Resources: https://www.cdc.gov/lyme/index.html

    Wormser GP, Dattwyler RJ, Shapiro ED, Halperin JJ, Steere AC, Klempner MS, Krause PJ, Bakken JS, Strle F, Stanek G, Bockenstedt L, Fish D, Dumler JS, Nadelman RB. The clinical assessment, treatment, and prevention of lyme disease, human granulocytic anaplasmosis, and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America. Clin Infect Dis. 2006 Nov 1;43(9):1089-134.

    Seriburi V, Ndukwe N, Chang Z, Cox ME, Wormser GP. 2012. High frequency of false positive IgM immunoblots for Borrelia burgdorferi in clinical practice. Clin Microbiol Infect 18:1236–1240

  5. Weiskopf J, Scott S. 2015. Asymptomatic bacteriuria, what are you treating? JAMA Intern Med 175:344-5.

    Nicolle LE, Gupta K, Bradley SF, Colgan R, DeMuri GP, Drekonja D, Eckert LO, Geerlings SE, Koves B, Hooton TM, Juthani-Mehta M, Knight SL, Saint S, Schaeffer AJ, Trautner B, Wullt B, Siemieniuk R. 2019. Clinical Practice Guideline for the Management of Asymptomatic Bacteriuria: 2019 Update by the Infectious Diseases Society of America. Clin Infect Dis 68:e83-e110.