Researchers from Johns Hopkins Medicine in Baltimore have identified a critical issue in infection prevention: the absence of a standard definition for blood culture contamination. This lack of consensus may lead to a rise in false positives and Central Line Associated Blood Stream Infections (CLABSIs).
Lead author Valeria Fabre, MD, an associate professor of medicine in infectious diseases at Johns Hopkins University School of Medicine, expresses concern over the variation in blood culture contamination definitions across hospitals. The absence of a standard definition may give detrimental false assurance that a hospital’s blood culture contamination rates are within optimal levels, when they might be exceedingly high and thus, potentially unsafe. Blood culture contamination definition directly impacts quality improvement measures in hospitals, according to the study.
It is pivotal to understand that blood cultures are vital diagnostic tools used by acute care hospitals for early detection of infections. However, their contamination can lead to false positives or incorrect diagnoses of bacterial infections, prompting unnecessary antibiotic usage and extended hospital stays. Healthcare institutions aim to restrict contamination to below 3% of all conducted blood cultures, striving for an ideal rate of 1% or less, aligning with the recommendations of the Clinical and Laboratory Standards Institute.
The study involved a survey of 52 acute care hospitals in 19 states and the District of Columbia, investigating over 360,000 blood culture samples collected over two years. The research findings were published in the Journal of Clinical Microbiology. Interestingly, about two-thirds of the surveyed hospitals used blood culture contamination criteria from either the Clinical and Laboratory Standards Institute or the College of American Pathologists.
Meanwhile, a smaller percentage based their contamination criteria on local definitions or an amalgamation of CAP/CLSI criteria and an exhaustive list of nonpathogenic skin surface microorganisms from the National Healthcare Safety Network. Half of the hospitals strived for a contamination threshold of less than 3%. Notably, only a handful of hospitals tracked blood culture quality measures, such as the quantity of blood culture bottles collected or blood culture positivity rates. These metrics offer significant scope for enhancing the diagnosis of bloodstream infections, states Dr. Fabre.
The study also signaled a correlation between increased blood culture contamination and CLABSIs rates. Every 1% surge in blood culture contamination resulted in a 9% escalation in CLABSIs. Given these findings, it is vital for professionals in the healthcare sector to pursue standardized definitions for blood culture contamination to ensure enhanced infection prevention methods.