A Single Negative Result for van Quantitative PCR on Enrichment Broth Can Replace Five Rectal Swab Cultures in Screening for Vancomycin-Resistant Enterococci

• Published in: Journal of clinical microbiology Vol. 55; no. 7; pp. 2261 - 2267
• Main Authors: Fonville, J M, van Herk, C M C, Das, P H A C, van de Bovenkamp, J H B, van Dommelen, L
• Format: Journal Article
• Language: English
• Published: United States American Society for Microbiology 01.07.2017
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Bacteriological Techniques - methods; Bacteriology; Female; Humans; Male; Mass Screening - methods; Middle Aged; Molecular Diagnostic Techniques - methods; Predictive Value of Tests; Real-Time Polymerase Chain Reaction - methods; Vancomycin-Resistant Enterococci - isolation & purification; Young Adult; VRE; culturing; qPCR
• ISSN: 0095-1137; 1098-660X
• DOI: 10.1128/JCM.00258-17

The increased incidence of infections by vancomycin-resistant (VRE) causes an accumulation of patients who are either colonized with VRE or flagged as potentially colonized with VRE. Since such patients require precautionary isolation upon admission to a hospital, rapid methods to establish VRE colonization status would improve patient care and optimize hospital operation. We evaluated quantitative PCR (qPCR) on one enrichment broth as a VRE-screening approach. We obtained 255 sets of five rectal specimens from 243 patients. The specimens were cultured using an amoxicillin-containing enrichment broth. Subsequently, a chromogenic agar was incubated and suspect colonies were inoculated on a blood agar plate and characterized by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF), followed by a vancomycin Etest in cases in which spp. were detected. The culturing results were compared with the outcome of qPCR on all enrichment broths of the first rectal swab. The qPCR was positive for 43% of the sample sets ( , = 5; , = 101; and , = 3). Based on culture data, 20 (7.8%) of the sets were VRE positive in at least one of five samples. The negative predictive value of qPCR on the first enrichment broth was 99.3%. With a cutoff quantification cycle ( ) value of >35 to discriminate negative and positive samples, 87% of the negative patients can be identified within a day after obtaining the sample, compared to 7 days in the culturing approach. VRE screening using qPCR on one enrichment broth can quickly identify non-VRE-colonized patients and therefore decrease costs and limit unnecessary isolation restrictions.