In the absence of evidence-based laboratory guidelines, the workup and interpretation of tracheal aspirate (TA) cultures remains controversial and confusing within the fields of clinical microbiology, infectious diseases, and critical care. Between 22 January and 24 February 2020, we conducted a national, web-based survey of microbiology laboratory personnel in free-standing pediatric hospitals and adult hospitals containing pediatric facilities regarding the laboratory practices used for TA specimens. We hypothesized there would be substantial center-level variability in laboratory processing of TA cultures. The response rate for the survey was 48% (73/153). There was a high level of variability in the criteria used for all processes, including specimen receipt, Gram staining, and culture reporting. Most respondents (77%) reported they do not reject TA specimens based on Gram stain criteria, and 44% of labs do not require that a minimum number of Gram stain fields be reviewed prior to reporting results. Overall, nonacademic hospital laboratories and pediatric-only laboratories are more likely to identify, report, and perform susceptibility testing on organisms from TA cultures, regardless of organism quantity or predominance. There is a substantial amount of process variability among pediatric microbiology laboratories that affects TA culture reporting, and which guides treatment decisions. This variation within and among labs makes clinical outcome studies related to TA cultures difficult to interpret. This study serves as a pragmatic step in informing the development of robust clinical guidelines. Clinical outcome and implementation studies are necessary to determine the effectiveness of guidelines for TA cultures.
Keywords: bacteriology; clinical laboratory; clinical microbiology; critical care; pneumonia; respiratory pathogens; stewardship; tracheal aspirate.
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