A cost-effective interdisciplinary approach to microbiologic send-out test use.

CONTEXT: Use of reference laboratories for selected laboratory testing (send-out tests) represents a significant source of laboratory costs. As the use of more complex molecular analyses becomes common in the United States, strategies to reduce costs in the clinical laboratory must evolve in order to provide high-value, cost-effective medicine. OBJECTIVE: To report a strategy that employs clinical pathology house staff and key hospital clinicians in the effective use of microbiologic send-out testing. DESIGN: The George Washington University Hospital is a 370-bed academic hospital in Washington, DC. In 2012 all requisitions for microbiologic send-out tests were screened by the clinical pathology house staff prior to final dispensation. Tests with questionable utility were brought to the attention of ordering clinicians through the use of interdisciplinary rounds and direct face-to-face consultation. RESULTS: Screening resulted in a cancellation rate of 38% of send-out tests, with proportional cost savings. Nucleic acid tests represented most of the tests screened and the largest percentage of cost saved through screening. Following consultation, requested send-out tests were most often canceled because of a lack of clinical indication. CONCLUSIONS: Direct face-to-face consultation with ordering physicians is an effective, interdisciplinary approach to managing the use of send-out testing in the microbiology laboratory.

Induction of MRSA Biofilm by Low-Dose ß-Lactam Antibiotics: Specificity, Prevalence and Dose-Response Effects.

Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of hospital- and community-associated infections. The formation of adherent clusters of cells known as biofilms is an important virulence factor in MRSA pathogenesis. Previous studies showed that subminimal inhibitory (sub-MIC) concentrations of methicillin induce biofilm formation in the community-associated MRSA strain LAC. In this study we measured the ability sub-MIC concentrations of eight other ß-lactam antibiotics and six non-ß-lactam antibiotics to induce LAC biofilm. All eight ß-lactam antibiotics, but none of the non-ß-lactam antibiotics, induced LAC biofilm. The dose-response effects of the eight ß-lactam antibiotics on LAC biofilm varied from biphasic and bimodal to near-linear. We also found that sub-MIC methicillin induced biofilm in 33 out of 39 additional MRSA clinical isolates, which also exhibited biphasic, bimodal and linear dose-response curves. The amount of biofilm formation induced by sub-MIC methicillin was inversely proportional to the susceptibility of each strain to methicillin. Our results demonstrate that induction of biofilm by sub-MIC antibiotics is a common phenotype among MRSA clinical strains and is specific for ß-lactam antibiotics. These findings may have relevance to the use of ß-lactam antibiotics in clinical and agricultural settings.