Comparison of PCR/Electron Spray Ionization-Time-of-Flight-Mass Spectrometry versus Traditional Clinical Microbiology for Active Surveillance of Organisms Contaminating High-Use Surfaces in a Burn Intensive Care Unit, an Orthopedic Ward and Healthcare Workers.

摘要

Background: Understanding nosocomial pathogen transmission is restricted by culture limitations. Novel platforms, such as PCR based electron spray ionization time of flight mass spectrometry (ESI TOF MS), may be useful as investigational tools. Methods: Traditional clinical microbiology (TCM) and PCR/ESI TOF MS were used to recover and detect microorganisms from the hands and personal protective equipment of 10 burn intensive care unit (ICU) healthcare workers providing clinical care at a tertiary care military referral hospital. High use environmental surfaces were assessed in 9 burn ICU and 10 orthopedic patient rooms. Clinical cultures during the study period were reviewed for pathogen comparison with investigational molecular diagnostic methods. Results: From 158 samples, 142 organisms were identified by TCM and 718 by PCR/ESI TOF MS. The molecular diagnostic method detected more organisms (4.5 + or - 2.1 vs 0.9 + or - 0.8, p<0.01) from 99% vs 67% of samples (p<0.01). TCM detected S. aureus in 13 samples vs 21 by PCR/ESI TOF MS. Gram negative organisms were less commonly identified than gram positive by both methods; especially by TCM. Among all detected bacterial species, similar percentages were typical nosocomial pathogens (18-19%) for TCM vs. PCR/ESI TOF MS. PRC/ESI TOF MS also detected mecA in 112 samples, vanA in 13, and KPC 3 in 2. MecA was associated (p<0.01) with codetection of coagulase negative staphylococci but not S. aureus. No vanA codetected with enterococci; one KPC 3 was detected without Klebsiella spp. Conclusions: In this pilot study, PCR/ESI TOF MS detected more organisms, especially gram negatives, compared to TCM, but the current assay format is limited by the number of antibiotic resistance determinants it covers. Further large scale assessments of PCR/ESI TOF MS for hospital surveillance are warranted.