title: Rectal screening for Klebsiella pneumoniae carbapenemases: comparison of real-time PCR and culture using two selective screening agar plates.
abstract: Klebsiella pneumoniae carbapenemases (KPCs) have recently been described in Chicago, IL, especially among residents of long-term acute care hospitals (LTACHs). These patients are frequently transferred to local Chicago hospitals for higher acuity of medical care, and rapid detection and isolation of KPC-colonized LTACH residents may interrupt the introduction of KPCs into acute care hospitals. We evaluated the performance of a real-time PCR for bla(KPC) from enrichment broth versus direct plating of rectal surveillance swabs on two selective culture media, CHROMagar extended-spectrum-β-lactamase (ESBL) and vancomycin, amphotericin B, ceftazidime, and clindamycin (VACC) plates. Rectal surveillance swabs were collected as part of a point prevalence study of KPC carriage rates among 95 residents of two Chicago area LTACHs. Discrepant results between PCR and culture were resolved by subculturing the enrichment broth. Overall, 66 of 95 patients (69.5%) were colonized with KPCs, using the cumulative results of culture as a reference standard. Real-time PCR from enrichment broth was positive in 64 of 66 (97%) colonized patients, including nine surveillance swabs that were missed by both selective culture media. PCR demonstrated higher sensitivity, 97.0%, than culture using either CHROMagar or VACC plates (both with sensitivity of 77.3%). In addition, turnaround time was significantly shorter for the PCR-based method than for culture, with a mean of 24 h versus 64 to 72 h for CHROMagar and VACC plates (P < 0.0001). Overall, PCR for bla(KPC) represents the best screening test for KPCs with significantly higher sensitivity and with less hands-on time, resulting in a shorter time to results.
authors.affiliation: Rush University Medical Center, Chicago, Illinois, USA. Kamaljit_Singh@rush.edu
authors.forename: Kamaljit
authors.initials: K
authors.lastname: Singh
authors.forename: Kathy A
authors.initials: KA
authors.lastname: Mangold
authors.forename: Kody
authors.initials: K
authors.lastname: Wyant
authors.forename: Donna M
authors.initials: DM
authors.lastname: Schora
authors.forename: Barbara
authors.initials: B
authors.lastname: Voss
authors.forename: Karen L
authors.initials: KL
authors.lastname: Kaul
authors.forename: Mary K
authors.initials: MK
authors.lastname: Hayden
authors.forename: Vishnu
authors.initials: V
authors.lastname: Chundi
authors.forename: Lance R
authors.initials: LR
authors.lastname: Peterson
mesh_terms: D000362:Agar; D001426:Bacterial Proteins / Q000032:analysis* / Q000235:genetics*; D001431:Bacteriological Techniques / Q000379:methods*; D002641:Chicago; D002863:Chromogenic Compounds / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry*; D006761:Hospitals; D006801:Humans; D007710:Klebsiella Infections / Q000382:microbiology*; D007711:Klebsiella pneumoniae / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification; D008403:Mass Screening / Q000379:methods; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D012007:Rectum / Q000382:microbiology; D012680:Sensitivity and Specificity; D013997:Time Factors; D001618:beta-Lactamases / Q000032:analysis* / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D002863:Chromogenic Compounds; D003470:Culture Media; D000362:Agar; D001618:beta-Lactamases; C063912:carbapenemase