‘‘Salvage Microbiology’’: Detection of Bacteria Directly from Clinical Specimens following Initiation of Antimicrobial Treatment
journal contributionposted on 2014-01-09, 00:00 authored by John J. Farrell, Rangarajan Sampath, David J. Ecker, Robert A. Bonomo
BACKGROUND: PCR coupled with electrospray ionization mass spectrometry (ESI-MS) is a diagnostic approach that has demonstrated the capacity to detect pathogenic organisms from culture negative clinical samples after antibiotic treatment has been initiated.  We describe the application of PCR/ESI-MS for detection of bacteria in original patient specimens that were obtained after administration of antibiotic treatment in an open investigation analysis. METHODS: We prospectively identified cases of suspected bacterial infection in which cultures were not obtained until after the initiation of antimicrobial treatment. PCR/ESI-MS was performed on 76 clinical specimens that were submitted for conventional microbiology testing from 47 patients receiving antimicrobial treatment. FINDINGS: In our series, 72% (55/76) of cultures obtained following initiation of antimicrobial treatment were non-diagnostic (45 negative cultures; and 10 respiratory specimens with normal flora (5), yeast (4), or coagulase-negative staphylococcus (1)). PCR/ESR-MS detected organisms in 83% (39/47) of cases and 76% (58/76) of the specimens. Bacterial pathogens were detected by PCR/ESI-MS in 60% (27/45) of the specimens in which cultures were negative. Notably, in two cases of relapse of prosthetic knee infections in patients on chronic suppressive antibiotics, the previous organism was not recovered in tissue cultures taken during extraction of the infected knee prostheses, but was detected by PCR/ESI-MS. CONCLUSION: Molecular methods that rely on nucleic acid amplification may offer a unique advantage in the detection of pathogens collected after initiation of antimicrobial treatment and may provide an opportunity to target antimicrobial therapy and "salvage" both individual treatment regimens as well as, in select cases, institutional antimicrobial stewardship efforts.
This work was supported in part by the Veterans Affairs Merit Review Program, the National Institutes of Health (Grant AI072219-05 and AI063517-07), and the Geriatric Research Education and Clinical Center VISN 10.
Publisher Statement© 2013 Farrell et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. © 2013 by Public Library of Science, PLoS ONE