ABSTRACT
Introduction- Carbapenemase-producing organisms (CPO) have been identied as an urgent healthcare threat. The spread of carbapenemase-producing Enterobacterales (CPE) is a global health problem of great concern. Rapid detection of carbapenemase-producing organisms is clinically desirable for hospital infection control and antibiotic stewardship. Recently, an on-demand polymerase chain reaction (PCR) assay, namely, the Xpert Carba- R assay, that requires less than an hour of turnaround time, had been developed for CPO detection in clinical samples to identify and guide infection control programs to contain the spread of CPO within a hospital. Carba-R assay is a Objective- qualitative multiplex real-time PCR method that qualitatively detects and differentiates ve common carbapenemase genes (blaKPC, blaNDM, blaVIM, blaOXA-48, and blaIMP) directly from clinical samples or puried colonies within approximately 1 hour. This benets hospitals and patients by facilitating timely Infection Prevention & Control measures, thereby reducing risk of exposure, transmission and bed-days lost. In this study, the Xpert Carba-R assay was evaluated for Materials & Methods- detection of the ve carbapenemase genes (blaKPC, blaNDM, blaIMP, blaOXA-48, and blaVIM) in total of 40 non duplicate various clinical samples of admitted patients in tertiary care hospitals of Vadodara. We performed Carba-R on 40Result- isolates: 18 blood samples, 06 urine, 05 rectal swabs, 03 Endotracheal secretion, 03 Pus, 02 wound discharge, 01 Bronchoalveolar lavage uid, 01 sputum, and 01 ERCP stent isolates. 36/40 (90%) isolates had one or more carbapenemase genes. They were as follows: 19/40 (47.5%) both OXA48 and NDM , 12/40 (30%) NDM and 05/40(12.5%) OXA-48. There were 04/40 (10 %) isolates which were Carbapenem resistant on disc diffusion & VITEK but none of the resistant genes were detected possibly due to other resistant mechanism like efux pump and porin channels. Klebsiella pneumoniae was the most common isolate with CR, 34/40 (85%). The most frequent genes encountered in Klebsiella pneumoniae were both OXA48 and NDM, 19/34 (55.88%), NDM 08/34 (23.53%) followed by OXA 48, 05/34 (14.71%) and Out of 34 Klebsiella isolates, 02 isolates failed to detect any of these ve carbapenemase genes. Xpert Carba-R assay provides good reliable results for detection and Conclusion- differentiation of ve carbapenemase genes in clinical isolates. Compared to bacterial culture followed by PCR identication of resistance genes from colonies, the Carba-R assay reduced turnaround time from 48 to 72 hours to less than 1 hour. Carbapenemase genes were detected by the Carba-R assay in Klebsiella pneumoniae (34/40), Escherichia coli (5/40), Acinetobacter spp (1/40). The Carba-R assay detected 19 both OXA48 and NDM (47.5%), 12 blaNDM (30% and 05 blaOXA-48 (12.5%) genes. Laboratory detection of these genes may help improve patient outcomes by tailoring therapy. This study was conducted for understanding the molecular epidemiology of Carbapenemase producing Enterobacteriaceae in a tertiary care hospital. The combined use of the Xpert Carba-R assay and culture produces rapid and reliable results for the active surveillance of CPO in patients
ABSTRACT
BACKGROUND: As the spread of carbapenemase-producing Enterobacteriaceae poses a critical threat to public health, rapid detection of carbapenemase genes is urgently required for prompt initiation of appropriate antimicrobial therapy and infection control. We evaluated the performance of Xpert Carba-R v.2 (Cepheid, USA) compared with that of culture-based conventional PCR.METHODS: Using the results of 5,479 consecutive clinical rectal swabs, discrepant analysis (enriched culture followed by PCR) was performed for all discordant samples (N=100), which were Carba-R v.2-positive and culture-negative.RESULTS: Among the samples, 206 carbapenemase genes (3.6%) were detected by Carba-R v.2. The sensitivity and specificity were 95.0% and 98.1%, respectively. The positive predictive value (PPV) and negative predictive value (NPV) were 49.0% and 99.9%, respectively. Following discrepant analysis, the PPV increased to 73.5% and the low PPV (8.1%) of the 86 non-KPC improved to 48.8%. Among the 105 discrepancies, NDM was the most frequently observed (N=56), followed by KPC (N=26), VIM (N=10), IMP (N=8), OXA-48 (N=5). The threshold cycle values between discordant vs. concordant and resolved groups were significantly different (P<0.001).CONCLUSIONS: Carba-R v.2 is a rapid and sensitive method for detecting carbapenemase-encoding genes compared with culture-based conventional PCR. Most of our discrepant results were non-KPC genes. Thus, the clinical significance of the non-KPC positive cases detected by Carba-R v.2 should be investigated. This assay would be useful for deciding whether to isolate pre-exposed patients in hospital settings, based on the high specificity and NPV.
Subject(s)
Humans , Enterobacteriaceae , Infection Control , Korea , Methods , Polymerase Chain Reaction , Public Health , Sensitivity and SpecificityABSTRACT
Resumen Introducción: La detección de bacilos gramnegativos productores de carbapenemasas es compleja, existiendo actualmente varios test disponibles. La confirmación mediante la caracterización molecular de la enzima no está disponible en todos los laboratorios del país. Objetivo: Plantear una estrategia rápida, eficiente y sencilla para la detección y confirmación de carbapenemasas en cepas de bacilos gramnegativos. Material y Métodos: Se utilizaron 39 aislados productores y ocho no productores de carbapenemasas para evaluar los test fenotípicos Carba NP, CarbAcineto NP, Blue-Carba y validar el test molecular Xpert® Carba-R directo de la colonia en comparación con RPC convencional. Resultados: La sensibilidad para Carba NP, CarbAcineto NP y Blue-Carba fue de 79,5; 87,2 y 84,6%, respectivamente; mientras que la especificidad fue de 100; 100 y 87,5%, respectivamente. La concordancia entre RPC convencional y Xpert® Carba-R fue de 100%. El límite de detección para Xpert® Carba-R fue diferente según el tipo de carbapenemasa: 40,8 ufc/reacción par KPC y NDM y 30,6 ufc/reacción para VIM. Discusión: En aislados con susceptibilidad disminuida a carbapenémicos se propone realizar un tamizaje con CarbAcineto NP, para luego caracterizar la carbapenemasa con Xpert® Carba-R y adoptar las medidas de contención específica: para cada caso.
Introduction: The detection of carbapenemase-producing gram negative bacilli is complicated, because there are available multiple options of test. The confirmation of the enzyme by molecular characterization is not available in all laboratories in our country. Objective: To propose a fast, efficient and simple strategy to detect and confirm CPB. Materials and Methods: 39 CPB isolates and 8 non-producing were used to evaluate the phenotypic test Carba NP, CarbAcineto NP and Blue-Carba, validating the test Xpert® Carba-R, to be used directly with bacterial colonies with conventional PCR. Results: The sensitivity of Carba NP, CarbAcineto NP and Blue-Carba was 79,5; 87,2 y 84,6%, respectively; and specificity was 79.5; 87.2 and 84.6%, respectively. The limit of detection of Xpert® Carba-R was different for each carbapenemasa: 40.8 ufc/reaction to KPC and NDM and 30.6 ufc/reaction to VIM. Discussion: On isolates with decreased susceptibility to carbapenems we propose to use as screening the test CarbAcineto NP, follow by Xpert®Carba-R to characterize the carbapenemase and adopt specific infection control measures.
Subject(s)
Humans , Bacterial Proteins/biosynthesis , beta-Lactamases/biosynthesis , Gram-Negative Aerobic Bacteria/isolation & purification , Gram-Negative Aerobic Bacteria/enzymology , Anti-Bacterial Agents/pharmacology , Phenotype , Microbial Sensitivity Tests , Polymerase Chain Reaction , Bacteriological Techniques , Sensitivity and Specificity , Gram-Negative Aerobic Bacteria/drug effectsABSTRACT
Carbapenemase-producing organisms (CPO) are rapidly disseminating worldwide, and their presence in tertiary care hospitals poses a significant threat to the management of nosocomial infections. There is a need to control CPO, especially in intensive care unit (ICU) patients, because these organisms are resistant to most beta-lactam antibiotics and are easily transmitted. At present, the identification of CPO is time-consuming; hence, this study focused on the use of the Xpert CARBA-R assay (Cepheid, USA) to determine intestinal colonization rates of CPO in patients admitted to the ICU of a tertiary care hospital in Korea. Forty clinical stool samples were collected and inoculated both in a CARBA-R cartridge and in conventional culture plates. The CARBA-R assay required only ~one hour to screen CPO, while the time required for conventional culture was over three days. We also found that the prevalences of intestinal colonization by carbapenem-resistant organisms and Enterobacteriaceae were 17.5% (7 out of 40) and 7.5% (3 out of 40), respectively. Among the colonizing strains, three that contained carbapenemase, including Klebsiella pneumonia carbapenemase (KPC), and imipenem (IMP) and Verona integron-mediated metallo-beta-lactamase (VIM) were found. With its convenience, the Xpert CARBA-R assay can be included in CPO surveillance strategies.