Rapidec Carba NP Research Articles

Incidence of carbapenem-resistant Escherichia coli ST2437 of clinical origin harbouring blaOXA-144 gene: a report from India.

Carbapenem-resistant Escherichia coli has been categorized as a pathogen of critical priority by the World Health Organization as it is highly infectious with high mortality and morbidity rates and widespread transmission potential. Carbapenem resistance is primarily mediated by carbapenemase-encoding genes and, additionally, through intrinsic factors. In India, over the years, carbapenemase-encoding genes have been reported from diverse clinically significant pathogens. The present study identifies E. coli of clinical origin that harbours blaOXA-144. The study isolate was obtained from a tertiary referral hospital in northeast India. Carbapenemase production was investigated through culture on chromogenic agar and Rapidec Carba NP test as per manufacturer's instructions. Susceptibility of the isolate was performed by the Kirby-Bauer disc diffusion method and agar dilution method following CLSI guidelines. PCR targeting carbapenemase-encoding genes was performed, followed by transformation and conjugation experiments. Whole-genome sequencing of the isolate was done through the Illumina sequencing platform and the data were analysed using the Centre for Genomic Epidemiology database. BJD_EC180 is 6 919 180 bp in length and consists of six rRNA operons, 111 tRNA, and 6849 predicted protein-coding sequences. BJD_EC180 belonged to ST2437 and harboured the carbapenemase-encoding gene blaOXA-144 with ISAba1 upstream, along with multiple antibiotic resistance genes conferring clinical resistance towards beta-lactams, aminoglycosides, amphenicols, sulphonamides, tetracyclines, trimethoprim, and rifampin. Carbapenem-resistant E. coli harbouring blaOXA-144 associated with insertion sequence pose a serious health threat as their mobilization into carbapenem non-susceptible strains that will contribute to the resistance burden and therefore, needs urgent monitoring.

Detection of Carbapenem-resistance in CRE by Comparative Assessment of RAPIDEC® CARBA NP and Xpert™Carba-R Assay.

Carbapenem-resistant Enterobacteriaceae (CRE) infections resist nearly most available antimicrobials, resulting in poor clinical outcomes. Saudi Arabia has a relatively high CRE prevalence. This study aims to evaluate the sensitivity of Rapidec Carba NP test and GeneXpert Carba-R assay compared with conventional manners for detection of carbapenemase-producing Enterobacteriaceae. This is a cross-sectional study including a total of 90 CRE isolates examined at two tertiary hospitals in KSA from October 2020 to December 2021. Gram-negative Enterobacteriaceae were identified by using Vitek 2 system and were furtherly tested for imipenem and meropenem susceptibility by E- test strips, followed by Rapidec Carba NP test and the Xpert™Carba-R assay. Carbapenem-resistant K. pneumoniae (78.9%) and carbapenem-resistant E. coli (14.4%) were the two most common isolates species. Colistin (98.9%) and tigecycline (88.9%) were the most effective antibiotics against CRE isolates, followed by amikacin (52.2%), gentamicin (33.3%), cotrimoxazole (15.6%), and ciprofloxacin (8.9%). blaOXA-48 was the predominant carbapenemase gene (44.4%), followed by blaNDM (32.2%). blaKPC gene was not detected. The Rapidec Carba NP and the Xpert™Carba-R demonstrated an overall sensitivity of 69.3% and 88%, respectively, in comparison to gold standard detection of meropenem and imipenem resistance by Vitek 2 system and E- test strips. RAPIDEC® CARBA NP may be a beneficial screening test for detecting CRE, but for confirmation of the results, Xpert Carba-R assay is more sensitive, significantly lowering the turnaround time compared to reference traditional methods. The information on carbapenemase genes may be used for epidemiologic purposes and outbreak management.

Comparative Evaluation of Three Phenotypic Tests-Carba NP, Modified Carba NP and Rapidec Carba NP Test for Rapid Detection of Carbapenem Resistance in Blood Culture Isolates of Escherichia coli in an ICU Setting.

To determine the antibiotic resistance pattern, the prevalence of extended-spectrum beta-lactamases (ESBLs) and carbapenem resistance in blood culture isolates of E. coli. Further, we evaluated and compared Carba NP, Modified Carba NP and a kit-based Rapidec Carba NP test to detect carbapenem resistance rapidly. Twenty-six carbapenem-resistant strains and four susceptible strains were selected. The three methods mentioned above were evaluated as per Clinical Laboratory Standards Institute (CLSI). These tests are based on biochemical detection of the hydrolysis of the beta-lactam ring of a carbapenem-imipenem, followed by the colour change of a pH indicator. Carba NP test was positive in 24 out of 26 isolates; the Modified Carba NP and Rapidec Carba NP tests were positive for all the isolates (26/26). All the carbapenemase non-producers (100%, 04/04) were negative. Modified Carba NP is a more effortless and inexpensive alternative to the Carba NP test, allowing the detection of carbapenemase activity directly from bacterial cultures of Enterobacteriaceae. The test could be used in low-income countries with large reservoirs for carbapenemase producers and can be implemented in any laboratory worldwide.

First report of Molecular Epidemiology of Carbapenem Resistant Enterobacteriaceae from a Tertiary Level Hospital in Rajasthan, Western India

Background: Carbapenem Resistant Enterobacteriaceae (CRE) are emerging at an alarming rate and pose a significant global threat. Objective: To conduct phenotypic and genotypic characterization of CRE strains from Rajasthan, Western India. Methodology: This was a prospective observational study conducted in Department of Microbiology, Dr S.N. Medical College, Jodhpur, Rajasthan from October to December 2018. All clinical samples received during the study period were processed and bacterial identification and antimicrobial susceptibility tests were performed according to standard microbiological guidelines. A total of 14 non duplicate carbapenem resistant clinical isolates of E coli and K pneumoniae were included in the study and subjected to Rapidec Carba NP test. Carbapenemase‑ encoding genes were amplified by multiplex polymerase chain reaction (PCR). PCR amplified products from three random isolates were subjected to Sanger sequencing. Results: Amikacin remained active against 36% isolates. All isolates were found to be susceptible to colistin and tigecycline. Carbapenemase production by Rapidec Carba NP test was noted in all (14/14) study isolates. All isolates were found to harbour ≥ 1 carbapenemase gene. The most common resistance gene observed was blaoxa (86%) followed by blaNDM (79%). None of the CRE isolates included in our study showed production of KPC enzymes. The sequences were analysed using BLAST analysis and were confirmed to be matching to OXA-48/181 and NDM-1. Conclusions: Growing carbapenem resistance is an important issue which needs urgent attention and blaOXA is an emerging mechanism of resistance among clinical CRE isolates in our setting Keywords: Carbapenem resistant Enterobacteriaceae, Phenotypic tests, Carbapenemase gene, Polymerase chain reaction

Detection of Carbapenem-resistant Enterobacteriaceae by Real-Time PCR and Assessment of Hospitalization Related Risk Factors Associated with their Fecal Carriage: A Case-control Study

Opportunistic behavior of commensal bacteria during severe infection, especially of the intestine is always considered as a predisposing threat for the severely ill patient admitted to hospitals. A descriptive-analytical case-control study was carried out to detect the prevalence and risk factor analysis of fecal carriage of Carbapenem-resistant Enterobacteriaceae. Patients having fecal carriage of Carbapenem-resistant Enterobacteriaceae were considered as cases and patients who were without Carbapenem-resistant Enterobacteriaceae were taken as the control in a proportion of 1:4. Carbapenem-resistant Enterobacteriaceae (CRE) was confirmed by both conventional as well as molecular methods. Methods such as Combined Disk Test, mCIMtest, and RAPIDEC CarbaNP Test were used for phenotypic identification of CRE, Whereas Real-Time (RT)-PCR was used for the detection of bla-gene encoded for CRE (blaNDM1, blaVIM, blaKPC, blaIMP, and blaOXA48). All patients belonging to medicine wards were included in the study. we screened 436 patients during the study and found 160 patients suitable for our study, out of which 32 (20%) were cases and 128 (80%) were controls. We found a total number of 25 genes out of 16 isolates, where NDM 1 was identified in maximum numbers followed by KPC &VIM. Standard statistical analyses such as chi-squire and odd ratios were conducted to determine the risk factor of different variables. Stepwise multiple logistic regressions were carried out, where we found, that transfer from other wards to medicine ward, use of nebulizer and intravenous catheter, and use of multiple antibiotics were still statistically significant. Implementation of Multi-modal colonization prevention and control is the need for the present situation throughout the world.

Detection of intestinal colonization by carbapenem-resistant Enterobacteriaceae (CRE) among patients admitted to a tertiary care hospital in Egypt

BackgroundThe irrational use of carbapenems in the last years lead to the emergence of carbapenem-resistant Enterobacteriaceae (CRE). This study aimed at determining the prevalence of CRE intestinal carriage among admitted patients in a tertiary care hospital in Egypt, to characterize carbapenemase-producing genes and to identify possible risk factors of CRE colonization. One hundred rectal swabs were collected from patients within 48 h of hospital admission. Culture was done on chromogenic media and then identification and antibiotic susceptibility testing were done using Vitek 2 compact system. Carbapenemase production was confirmed by Rapidec Carba NP test and by multiplex PCR for blaOXA-48-like, blaNDM-like, blaVIM-like, blaIMP-like and blaKPC-like.ResultsA total number of 36 CRE isolates were recovered from 28 patients. Thus, the prevalence of CRE colonization was 28%. Escherichia coli (83%), followed by Klebsiella pneumoniae (17%) were the main species. History of recent hospitalization and prior antibiotic intake were statistically significant risk factors predisposing to CRE colonization. Rapidec Carba NP gave positive results in 29/36 CRE isolates, whereas seven isolates gave negative results; six of them harbored blaOXA-48-like. Overall, the blaOXA-48-like was detected in 24/36 (66.7%), followed by blaNDM-like in 11/36 (30.6%) and lastly blaVIM-like in 1/36 (2.8%).ConclusionsOur findings confirm that CRE colonization is disseminating in our healthcare facility, a fact that should be considered as possible pathogens causing infections in high risk patients. Strict infection control measures should be applied to all CRE carriers at hospital admission and a proper antimicrobial stewardship program should be followed in clinical settings.

Report on carbapenemase-producing rare sequence types of Escherichia coli and Enterobacter hormaechei

Introduction and Aim: Carbapenem Resistant Enterobacteriaceae (CRE) have emerged at an alarming rate. Multi locus sequence typing (MLST) is an important parameter for identifying drug resistant organisms. The present study was carried out for elucidating the mechanisms of CRE and MLSTs associated with CRE. Materials and Methods: CRE (n=14) were obtained from various clinical samples and subjected to Rapidec Carba NP (CNP) test and multiplex polymerase chain reaction (M-PCR) and five isolates proceeded for whole genome sequencing (WGS). ?-lactamase (bla) genes were analysed using Resfinder and CARD tool. Bioinformatics tools: mlplasmids, plasmid finder, mobile element finder, and Center for Genomic Epidemiology (CGE) toolbox were used. Results: All isolates (n=14) were positive for CNP and bla genes using M-PCR. Isolates (J21, J22, J23, J27) were identified as Escherichia coli while (J34) was Enterobacter hormaechei. MLST showed E. coli isolates (J21& J22) as ST648; E. coli (J23) was ST940; E. coli (J27) was ST 2851, and E. hormaechei (J34) was closest to ST1325. Genes blaTEM, blaNDM & blaampC were found to be present in all isolates; blaCTX-M was present in all E. coli isolates but not in E. hormaechei. blaOXA was present in E. coli (J23) and in E. hormaechei (J34); while ESBL blaSFO-1 in E. hormaechei (J34). Conclusion: ESBLs (blaTEM & blaCTXM) and metallo beta-lactamase -MBL (blaNDM) cause carbapenem resistance in rare sequence types of E. coli while; ESBL (blaSFO-1) and MBL (blaNDM) cause carbapenem resistance in E. hormaechei.

Performance Evaluation of Diagnostic Assays for Detection and Classification of Carbapenemase-Producing Organisms.

Rapid and accurate detection can help optimize patient treatment and improve infection control against nosocomial carbapenemase-producing organisms (CPO). In this study, a total of 217 routine clinical isolates (Enterobacterales and A. baumannii), including 178 CPOs and 39 non-CPOs, were tested to evaluate the performance of six phenotypic carbapenemase detection and classification assays, i.e., BD Phoenix CPO detect panel, Rapidec Carba-NP, O.K.N detection kit, and three carbapenem inactivation methods (CIMs; mCIM, eCIM, sCIM). The overall detection sensitivity and specificity were 98.78% (95.21–99.79%) and 79.49% (63.06–90.13%), respectively, for the BD phoenix CPO P/N test; 91.93% (86.30–95.45%) and 100% (88.83–100%), respectively, for the Rapidec Carba-NP; 98.06% (94.00–99.50%) and 97.44% (84.92–99.87%), respectively, for mCIM; and 96.89% (92.52–98.85%) and 94.87% (81.37–99.11%), respectively, for sCIM. The classification sensitivity and specificity for the BD phoenix CPO Ambler test, the O.K.N detection kit, and the mCIM and eCIM were 56.71% (48.75–64.34%) and 94.87% (81.37–99.11%), 99.28% (95.43–99.96%) and 100% (88.83–100%), and 92.90% (87.35–96.23%) and 97.44% (84.92–99.87%), respectively. All detection assays were reliable in detecting carbapenemase. However, the Rapidec Carba-NP and mCIM were insufficient in detecting OXA-48-like enzymes. The BD phoenix CPO detect panel had a strong ability to detect carbapenemase but failed to classify 48/59 (81.36%) KPC, 8/52 (15.38%) NDM, 8/22 (36.36%) OXA-23-like, and 6/11 (54.55%) dual enzymes. The O.K.N detection kit accurately detected and differentiated KPC, NDM, and OXA-48-like enzymes existing alone or in combination. The results of this study will support reliable laboratory work tools and promote therapeutic and infection control decisions.

Comparison of sCIM and Other Phenotypic Detection Methods for Carbapenemase-Producing Enterobacterales.

ABSTRACTRapid detection and reporting of carbapenemase-producing Enterobacterales (CPE) is one of the top priorities of clinical microbiology laboratories. The Clinical and Laboratory Standards Institute recommends the modified carbapenem inactivation method (mCIM) as the preferred method for this purpose, but it requires a broth incubation process which can be cumbersome. Here, we compared the performance of mCIM with three alternative rapid CPE detection methods against a collection of genetically defined CPE, with most carrying blaIMP, and non-CPE clinical isolates. The sensitivities of mCIM, simplified carbapenem inactivation method (sCIM), Rapidec Carba NP, and NG-Test Carba 5 were 98.0%, 54.9%, 90.2%, and 72.5%, whereas the specificities were 89.5%, 84.2%, 89.5%, and 100%, respectively. Modification of the interpretive criteria of sCIM increased its sensitivity to 88.2% and specificity to 89.5%. The results suggest that mCIM is currently the optimal method for CPE detection in an epidemiological setting where CPE-producing IMP group carbapenemase is predominant. While sCIM is easier to perform, it requires further validation before it can be widely adopted as an alternative to mCIM in the clinical laboratory.IMPORTANCE Simple identification methods for carbapenemase-producing Enterobacterales are required for the clinical laboratory. The simplified carbapenem inactivation method (sCIM) is a carbapenemase detection method that can be performed with less hands-on time than mCIM, but its sensitivity and specificity were suboptimal compared with other phenotypic detection methods when tested against a collection of IMP-producing CPE. Insufficient inactivation of imipenem from inadequate inoculation was suspected as the cause. While sCIM is easier to perform, it requires optimization before it can be widely adopted as an alternative to mCIM in the clinical laboratory.

Detection of carbapenamase production by Rapidec carba NP test among Gram negative isolates in a tertiary care hospital

Detection of carbapenamase production by Rapidec carba NP test among Gram negative isolates in a tertiary care hospital

Evaluation of a colorimetric test for the rapid detection of carbapenemase activity in Gram negative bacilli: the MAST® PAcE test.

The MAST® Carba PAcE test is a colorimetric test used to detect carbapenemase-producing Gram-negative bacilli from cultured colonies. The performances of this test were compared to β-CARBA™, Carba NP test and RAPIDEC® CARBA NP tests using a collection of 280 characterized isolates. Sensitivity and specificity of the MAST® Carba PAcE test were 79.8% (95%IC: 73.3%-85.1%) and 98.9% (95%IC: 92.9%-99.9%). The MAST® Carba PAcE sensitivity was the lowest mainly due to interpretation difficulties (particularly OXA-48-like).

Resistance to bacterial infection, complication occurring after cardiac surgery

To analyze the occurrence of resistant bacterial infection in patients undergoing cardiac surgery hospitalized in the surgical specialty hospital, in Erbil city, Iraq. A prospective study was done on a total of 138 patients operated and hospitalized in an intensive care unit and surgical wards. Bacterial isolates identification was done according to cultural characteristics, microscopic examination, some biochemical tests, analytic Profile Index 20E& API Staph, confirmed with VITEK® 2 compact system (BioMérieux). Antimicrobial susceptibility for disc diffusion tested to 17 antimicrobial agents. Resistance isolates were confirmed phenotypically for carbapenemase by Rapidec Carba NP Test (bioMe´rieux SA, Marcy-l'E´toile, France) for ESBLs producers by ESBL screening test VITEK 2 system. Molecularly blaIMP blaTEM, blaKPC, AmpC and blaCTX-M were detected by PCR. In 134 patients, 28.3% of patients got infected post-operatively. The most frequent source of isolation was from ICU patients (75%). Isolated bacteria included gram-positive 29 (54.7%) and gram-negative bacteria 24 (45.3%). Most frequently: Staphylococcus aureus (24.4%), each of pseudomonas aeroginosa, Klebsiella pneumonia (15.1%), Streptococcus spp. (11.3%), Escherichia coli (9.4%). Whereas included Coagulase Negative Staphylococci species (CoNS) (13.2%) and Enterococci species (5.7) Statistical analysis showed significantly higher sensitive isolates as compared with resistance isolates. Resistance to Carbapenems calss was 18.9% and Cephalosporins class 41.5% of isolates. The antimicrobial resistance pattern indicated that MDR bacterial isolates (81.1%) were widespread. Of the 34 phenotypically ESBL positive isolates, the ESBL genes (AmpC, blaCTX-M, and blaTEM) were amplified in 7(20.6), 6(17.6) and 6(17.6) isolates respectively. Out of 8 K. pneumonia (37.5%) harboring both blaAmpC and bla-CTX-M genes, while 6(75%) carries blaTEM. The blaCTX-M gene was found in only 1 (12.5%) out of 8 isolates of P. aeruginosa. While blaAmpC genotyping revealed that 1(7.7%) out of 13 Staph. aureus isolates were harboring it. Finally, 3(60%) out of 5 E. coli isolates harboring both AmpC and bla-CTX-M genes. Cardiac surgery patients wound show increasingly emerging strains of ESBL-producing gram-negative bacteria K. pneumonia, P. aeruginosa and E. coli especially patients prolonged in the intensive care unit.

Detection of Carbapenemase Production by Rapidec Carba NP Test among Gram Negative Isolates in a Tertiary Care Hospital

Detection of Carbapenemase Production by Rapidec Carba NP Test among Gram Negative Isolates in a Tertiary Care Hospital

Evaluation of two commercial methods for rapid detection of the carbapenemase-producing Klebsiella pneumoniae

In this study, we evaluated the performance of the two commercial methods (Rapidec Carba NP and NG-Test Carba-5) for the rapid detection of carbapenemase-producing Klebsiella pneumoniae. A total of 224 Klebsiella pneumoniae strains previously characterized for carbapenemase genes by polymerase chain reaction were included in the study. The strain collection included 30 non-carbapenemase producers, 85 OXA-48-like, 59 NDM, 14 IMP, 7 KPC, 7 VIM, 19 OXA-48-like plus NDM, and 3 KPC plus NDM producers. Rapidec Carba NP and NG-Test Carba 5 was performed according to the manufacturer's instructions. NG-Test Carba 5 correctly detected all carbapenemase-producing K. pneumoniae, however, Rapidec Carba NP failed to detect 41% of OXA-48-like producers even with extended incubation time. The overall sensitivity and specificity were 81,9% and 100% for Rapidec Carba NP, 100% and 100% for NG-Test Carba 5, respectively. Both tests seem to be fast and reliable for the detection of carbapenemase-producing K. pneumoniae especially for microbiology laboratories where molecular tests cannot be performed. However, Rapidec Carba NP with weak hydrolysis activity for OXA-48 like might be used in regions where OXA-48 is not prevalent. The additional advantage of NG-Test Carba 5 is that it specifically detects carbapenemases giving way to threat-related infections with an effective drug such as ceftazidime-avibactam or meropenem- vaborbactam.

Rapid detection of Enterobacterales that produce carbapenemases

PurposeThe rapid detection of carbapenemases among Enterobacterales in clinical laboratories is critical for management of patients, and infection prevention and control efforts. MethodsA study was designed to evaluate the performances of the RAPIDEC CARBA NP®, β-CARBA®, NG-Test CARBA 5®, modified carbapenem-inactivation method, and EDTA version (eCIM) assays against a global collection of Enterobacterales (n = 216) with diverse carbapenemases. ResultsThe RAPIDEC CARBA NP® assay had a sensitivity of 98.6% and specificity of 19.6% and β-CARBA® a sensitivity of 94% and specificity of 97.8%, but showed low sensitivity with Klebsiella Pneumoniae Carbapenemase (KPC)-containing isolates. The NG-Test CARBA 5® had an overall sensitivity of 96.3% and specificity of 100% and failed to detect isolates with blaIMP-13, blaIMP-14. The eCIM gave false- positive results with Oxacillinase (OXA)-48–like enzymes. ConclusionThe NG-Test CARBA 5® assay was technically simple and provided rapid accurate results on the types of carbapenemases. Such information has potential treatment benefits for patients.

Evaluation of the compatibility of phenotypic and molecular methods used to determine carbapenem resistance in enterobacterales isolates

Aim: Carbapenems are one of the most important options for clinicians with few treatment options in the clinic due to their low side effects, rapid diffusion into tissues and use in all age groups. Therefore, it is important to be able to detect carbapenemase-producing isolates at an early stage for appropriate patient management and for infection prevention and control procedures. Antibiotic resistance genes and enzymes of microorganisms can be determined by phenotypic and molecular methods in clinical microbiology laboratories. Phenotypic methods are cheap, easy and easy to repeat but determination of resistance gene regions by molecular methods is costly, requires labour-experienced personnel and is time consuming. Determining whether the isolates possess the carbapenemase enzyme by phenotypic tests will provide convenience both for the patient and early initiation of the treatment and directing the clinician to the treatment. In this study, we aimed to evaluate the compatibility of phenotypic methods (carbapenemase inactivation method and Rapidec Carba NP) and molecular methods (Polymerase Chain Reaction) used to determine carbapenem resistance in Enterobacterales isolates. Material and Methods: Carbapenem resistant 60 and sensitive 20 Enterobacterales isolates were included in the study. E-test agar gradient diffusion, CIM, Rapidec Carba NP methods and PCR were studied. The agreement between the methods was determined by using the kappa (κ) coefficient with the cohen kappa analysis method.Results: In carbapenem resistant isolates, meropenem MIK50 and MIK90 determined as 32µg/ml, 64µg/ml, imipenem MIK50 and MIK90 determined as 32µg/ml, 128µg/ml, respectively. OXA-48 was positive in 54 (90%) isolates and NDM-1 in 6 (10%) isolates. The susceptibility of the isolates with OXA-48 carbapenemase gene region was 94.4% by CIM test and 92.6% by Rapidec Carba NP test, respectively. When the Kappa coefficient was evaluated, a very good agreement was observed between both tests and OXA-48. However, in the isolates with NDM-1 gene region, no compliance with CIM test was observed but Rapidec Carba NP test showed very good agreement. Conclusion: Rapid carbapenemase testing, such as Rapidec Carba NP and CIM, can play an important role in preventing the development of health-related outbreaks caused by carbapenemase-producing isolates, enabling faster prevention and control of infection.

Molecular detection of carbapenemase-producing Pseudomonas aeruginosa isolated from intensive care units of surgical specialty hospital in Erbil city

Background: The emergence and spread of carbapenem-resistant Pseudomonas aeruginosa (CRPA) is a serious cause of nosocomial infections in critically ill patients. Objectives: The aim of this study was to determine the prevalence of CRPA and carriage of class B Metallo-β-lactamase resistant genes in intensive care units (ICUs) from patients with surgical-site infection or ventilator-associated pneumonia at a Surgical Specialty Hospital in Erbil city. Materials and Methods: During 6 months' study, a total of 80 clinical samples were collected from ICUs. The identification of P. aeruginosa in clinical specimens was confirmed by polymerase chain reaction (PCR) amplification of a molecular marker–oprL gene. Antimicrobial susceptibility was performed using Vitek-identification system. Screening of carbapenemase-producer isolates was confirmed using Rapidec Carba NP test. CRPA isolates were tested for the presence of metallo-β-lactamase (MBL)-encoding genes, including: blaVIM, blaIMP, and blaNDMby using PCR. Results: A total of 50 (62.5%) P. aeruginosa isolates were identified with antibiotic resistance profile (4% pan drug resistant [PDR], 20% extensively drug resistant [XDR] and 76% multidrug resistant). Twelve (24%) isolates were CRPA positive, in which the most prevalent MBL-encoding gene was blaVIM (58.3%), blaNDM (41.7%), and blaIMP (33.3%). Conclusions: Alarmingly, high prevalence of CRPA with predominance of MBL-encoding genes was detected. The XDR and PDR resistance phenotypes have become highly prevalent for this nosocomial pathogen in ICU patients that may cause a therapeutic impasse. The MBL-encoding genes were predominant among clinical isolates of P. aeruginosa. These findings emphasize on adherence to infection prevention and control standard precautions, early detection of CRPA isolates and development of to effectively reduce the burden of carbapenem resistance.

Detection of carbapenemases, AmpC and ESBL genes in Acinetobacter isolates from ICUs by DNA microarray

The accumulation of multiple inherent and acquired resistance mechanisms in Acinetobacter spp. results in emergence of “pandrug resistant” strains which is one of the major concerns in healthcare sectors worldwide. Surveillance of the carbapenemase/ extended-spectrum β-lactamases (ESBLs) genes in A. baumannii by phenotypic methods is challenging especially in developing countries, like Pakistan. In this context, a novel microarray (CT 103XL Check-MDR) assay was used for simultaneous detection of genes encoding clinically important carbapenemases and ESBLs. The results were compared with the phenotypic methods including MHT, Rapidec Carba NP, EDTA+DDST and Rosco (KPC/MBL). The results of the microarray were also confirmed by PCR. All of the strains of A. baumannii (47) were resistant to imipenem and meropenem. Microarray and PCR results showed presence of OXA-23 in all the isolates of A. baumannii while 36.17% also harbored PER. Rosco kit test showed 100% sensitivity to detect carbapenemases but exhibited low specificity to classify them. Rapidec Carba NP test has 100% sensitivity and specificity to detect the carbapenemases when compared with microarray. Sensitivity and specificity of microarray assay were 100% for bla-genes in comparison to PCR. This reveals that Check-MDR CT103 XL assay is an accurate method for the identification of ESBLs and carbapenemase genes in A. baumannii in comparison to the other methods.

Evaluation of the RAPIDEC CARBA NP, Conventional CarbaNP, and the Modified Carbapenem Inactivation Method (mCIM) Tests for Phenotypic Detection of Carbapenemase-Producing Organisms

Decreased susceptibility to carbapenems is being increasingly reported among Gram-negative organisms worldwide. It is of critical importance for patient management and infection control purposes to detect carbapenemase-producing organisms rapidly and reliably. In this study, the performance of the commercially available RAPIDEC CARBA NP test (bioMérieux, Durham, NC) was evaluated against the performance of the conventional CarbaNP and the modified Carbapenem Inactivation Method (mCIM) for the detection of carbapenemase activity in Enterobacteriaceae and Pseudomonas aeruginosa. A total of 73 Enterobacteriaceae and 32 Pseudomonas aeruginosa isolates were tested for carbapenemase activity using the RAPIDEC CARBA NP, conventional CarbaNP, and mCIM methods. Using available whole-genome sequence information, this collection included 72 isolates with and 33 isolates without carbapenemase genes. The isolates harboring a carbapenemase gene encoded 20 class A, 47 class B, and 5 class D–type β-lactamases. All methods were performed using bacteria from a single overnight blood agar plate. The conventional CarbaNP and mCIM were performed according to guidelines from the Clinical and Laboratory Standards Institute. The RAPIDEC CARBA NP was performed per the manufacturer’s instructions. The RAPIDEC CARBA NP detected 65 of 72 (90%) carbapenemase-producing isolates; the seven isolates yielding false-negative results included five Enterobacteriaceae with blaOXA-48-like and two with blaKPC-4 genes. The sensitivity and specificity were 90.2% and 100%, respectively, for the RAPIDEC test; 94.4% and 100% for conventional CarbaNP; and 100% and 81.8% for mCIM. The conventional CarbaNP detected all carbapenemase producers except four OXA-48-like–producing isolates. The mCIM, which accurately detected all carbapenemase producers, yielded false-positive results in six isolates of P aeruginosa. Overall, the RAPIDEC CARBA NP was easy to use and required less hands-on time than the conventional CarbaNP and mCIM methods. However, the RAPIDEC CARBA NP showed decreased sensitivity for detecting low-level activity carbapenemases such as OXA-48-like enzymes and KPC-4.

Carbapenemase detection using the β-CARBA test: Influence of test conditions on performance and comparison with the RAPIDEC CarbaNP assay

Carbapenemase detection using the β-CARBA test: Influence of test conditions on performance and comparison with the RAPIDEC CarbaNP assay