Comparison of Multidrug-Resistant Gram-Negative Pathogen Detection by Culture and Polymerase Chain Reaction (PCR) From Surveillance Samples
Year: 2015
Type: article
Abstract: Background. Rapid detection of Gram-negative multidrug resistant organisms (MDRO) in patient surveillance samples is important for infection prevention. Culture methods are considered less sensitive than PCR and can take longer to obtain, but PCR only detects the targets in the assay. We compared real-time PCR testing for CTX-M, KPC and NDM-1 from multiple body sites to culture for MDRO Enterobacteriaceae. We hypothesized that PCR testing would be the same or superior to culture and could replace it. Methods. Samples of throat, axilla and peri-anus were collected from ICU patients. For culture, swabs were plated to agar with ceftazidime and incubated overnight. Organisms were identified and susceptibility testing was performed to determine if MDRO. For PCR, a swab from each sample was incubated overnight in 10ml Tryptic Soy Broth with a 30 µg ceftriaxone disc. The broth was then tested for blaNDM, blaKPC and blaCTX-M as previously described by Mangold (J Clin Micro 2013;51:3423-5 and J Clin Micro 2011;49:3338-9). Culture results were compared to PCR and discrepancies resolved. For colonies confirmed as MDRO but negative by PCR, we investigated the presence of other β lactamase genes that might account for resistance. A multiplex PCR for TEM, SHV or OXA plasmids was performed as described previously (J Antimicrobial Chemother 2010; 65:490-5). Results. 1191 samples were collected from 1 April 2013 to 30 June 2014. Thirty patients were PCR positive/culture negative, but 25 were subsequently grown from the broth where the PCR test was taken, confirming the PCR result. In addition, culture grew 23 MDRO not detected by the designed PCR assay (12 TEM, 9 SHV, 2 mixed OXA:SHV producers), yielding 120 true positives. Performance of PCR and Culture for MDRO Conclusion. PCR recovered more of the targeted MDR Gram-negative bacteria than direct culture (p < 0.001), but including all possible MDROs indicated no difference in performance (p = 1). PCR is an important tool for infection prevention, but the broad range of genotypes responsible for Gram-negative MDROs challenge this as a single approach for effective surveillance. Disclosures. All authors: No reported disclosures.
Source: Open Forum Infectious Diseases
Authors: Donna Schora, Barbara Voss, Kathy Mangold, Sanchita Das, Richard Thomson, Irene Dusich, Marc-Oliver Wright, Becky Smith, Lance Peterson
Language: English
Subfield: Molecular Medicine
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $4,053
OpenAlex ID: W2588188124