I was able to attend the ASM Microbe 2025 conference because I received the Peggy Cotter Travel Award. I found many sessions to be directly related to my career in the clinical microbiology laboratory. This year’s topics covered the emerging pathogen C. auris, current conundrums and controversies, proper blood culture collection techniques and more!

Candidozyma auris is known to be a multidrug-resistant fungus that typically causes infection in the immunocompromised, commonly those in healthcare facilities. This fungus is closely related to C.haemulonii and C. duobushaemulonii. There is a rapid recontamination rate of C. auris in patient rooms at hospitals and long term care facilities. This microorganism is particularly a concern as it is found in the normal skin flora. It is easily spread and can cause opportunistic infection, as it has persistent colonization. Colonized patients are at a higher risk for invasive infection. In order to properly disinfect, disinfectant from the EPA list P is required. Almost all C. Auris strains are resistant to fluconazole, with some resistance to amphotericin B. Currently, C.
auris is listed as an urgent public health threat (CDC) and “critical” human fungal pathogen (WHO). Clinical microbiology laboratories have a responsibility for identifying this organism properly, so the appropriate antifungal medications can be used to treat the patient. Examples of identification are MALDI-TOF for pure colonies, PCR and use of CHROM agar.

There are various topics that are controversial in clinical microbiology. Topics covered in this meeting include urine culture workup, reporting AST values to clinicians, rejection criteria for respiratory cultures, and thioglycollate broth usage. One portion of the urine culture workup topic delves into the criteria for contamination, and if the same species of bacteria with the same AST results should be considered the same organism. Would this be helpful for the patients and clinicians? Typically, laboratories consider three organisms at >100,000 CFU/mL (or >50,000 CFU/mL) to be a contaminated culture, but what if two of those organisms that have different
morphotypes have the same identification and AST results? This was interesting to consider. Another controversial topic was reporting AST results in all cultures to be only available to the infection disease team and pharmacy. Some clinicians are known to choose antibiotics with the lowest MIC value, which is not always the best choice for the organism or patient. Rejection criteria for respiratory specimens was also an interesting topic as many questions could be raised on what that criteria is. Is it helpful or harmful to keep culture plates in the incubator of specimens that were rejected? Does it cover only sputum specimens? Or are tracheal and bronchial specimens also included? Aside from specimens, should we be looking at the number of PMNs and organisms in the Gram stain as a means of rejection? PMNs are indicators of infection, so the question is, should we be culturing a sputum specimen with no PMNs and no organisms seen? When using no PMNs and no organisms as a rejection criteria,
a statistically insignificant amount of pathogens were missed. These pathogens (i.e. S. aureus) were likely colonized in the patient and not the cause of infection. Thioglycollate broth usage was also a topic covered, specifically for how long broths are held, and what cultures to use them for. The benefit of thioglycollate is that it can grow fastidious organisms that do not grow on the agar plates. Holding thioglycollate broths for too long increases the workload for the MLS reading cultures. Sometimes, growth in thioglycollate could be considered contamination if the patient has no indication of infection and no growth on the agar. Holding the broths for an extended amount of time(i.e. 14, 21 days) should be by request only. An example on the bench
is reading cultures from daily shunt collection, and holding them 14 days or longer. Collecting these samples daily could introduce contamination.

The latest evidence based practices for blood cultures include utilizing rapid identification directly from blood culture bottles and methods to decrease blood culture contaminants. Both of these topics directly relate to the clinical microbiology blood culture bench. Rapid ID directly from blood culture bottles improves time to targeted therapy, length of stay at hospital, and decrease in mortality. Examples of RID are NAAT Hybridization Assay and MALDI-TOF. Evidence for decrease in blood culture contaminants shows use of chlorhexidine with or without alcohol reduced the risk by an average of 57%, diversion device (i.e. using heparin tube first then blood cx bottle) reduced risk by an average of 64%, specially trained phlebotomy team performing the draws reduced risk by an average of 41% and standardized procedure for using sterile technique reduced risk by 56%.

Overall, ASM Microbe 2025 was an amazing experience, and I would recommend anyone in the microbiology field to attend at least once. I am so grateful to have been able to attend and take this information back to my community!