Predominant Carbapenemase Research Articles

Characterization of carbapenemases, ESBLs, and plasmid-mediated quinolone determinants in carbapenem-insensitive Escherichia coli and Klebsiella pneumoniae in Riyadh hospitals.

The main objective of this work was to characterize carbapenemases, extended-spectrum β-lactamases (ESBLs), and plasmid-mediated quinolone resistance (PMQR) among carbapenem-insensitive Klebsiella pneumoniae and Escherichia coli clinical isolates which were isolated from three hospitals in Riyadh. Thirty-one carbapenem-insensitive isolates (21 K. pneumoniae and 10 E. coli) were recovered from March 2014 to May 2014. Susceptibility testing and phenotypic detection tests were used to characterize the classes of β-lactamases. PCR assays were performed for the detection of the genes encoding ESBL (blaCTX-M, blaTEM,blaSHV, and blaOXA-1), carbapenemase (blaKPC,blaGES,blaVIM, blaIMP, blaNDM, and blaOXA-48), and PMQR (qnrA, qnrB, qnrS, aac(6)-Ib-cr, qepA, oqxA, and oqxB) genes. All carbapenem-insensitive isolates were carbapenemase producers, with 41.9% and 58.1% being class B carbapenemases class D OXA-48, respectively. While the prevalence of ESBL producers was 80.6%. The following resistance genes were detected; OXA-48-like (58.1%), NDM-type (41.9%), CTX-M-1-like (77.4%), CTX-M-9-like (9.6%), TEM-1 (74.2%), OXA-1 (54.8%), SHV-1 (4.4%), qnrS (58.1%), qnrB (3.2%), and aac(6)-Ib-cr (51.6%). The predominant carbapenemases in the isolates that had carbapenem MIC≤4μg/ml and MIC≥12μg/ml were blaOXA-48-type and blaNDM-type respectively. CTX-M-1-like and qnrS were the dominant ESBL and PMQR genes, respectively. This is the first report in which qnrS was described in the isolates from Saudi Arabia.

Trends in carbapenemase-producing Enterobacteriaceae, France, 2012 to 2014.

In 2014, a total of 2,976 Enterobacteriaceae isolates with decreased susceptibility to carbapenems were received at the French Associated National Reference Center for Antibiotic Resistance (NRC) and were characterised for their molecular resistance mechanism to carbapenems and compared with results obtained during 2012 and 2013.The overall number of enterobacterial isolates with decreased susceptibility to carbapenems received at the NRC rapidly increased (more than twofold in two years) with a growing proportion of carbapenemase producers (23.1% in 2012 vs 28.6% in 2013 vs 36.2% in 2014). Between 2012 and 2014, the main carbapenemase type was OXA-48, with an increase in OXA-48 variants (mostly OXA-181) and NDM producers, whereas the number KPC producers decreased. We identified a potential spread of OXA-181 producers in the tropical region of Africa. Finally, OXA-48 and OXA-48-related enzymes remained the predominant carbapenemases in France. The number of carbapenemase-producing Escherischia coli isolates was multiplied by fivefold between 2012 and 2014, suggesting a possible dissemination in the community.

The emergence of carbapenem resistant Klebsiella pneumoniae in Malaysia: correlation between microbiological trends with host characteristics and clinical factors

BackgroundCarbapenem resistant Enterobacteriaceae is a growing concern worldwide including Malaysia. The emergence of this pathogen is worrying because carbapenem is one of the 'last-line' antibiotics. The main objective of this study was to determine the prevalence of genetic mechanisms and clinical risk factors of carbapenem resistant Klebsiella pneumoniae (K. pneumoniae) in Malaysia.MethodsIn this study, seventeen carbapenem resistant K. pneumoniae strains isolated from a tertiary teaching hospital in 2013 were studied. Minimal inhibitory concentration (MIC) of the bacterial strains was determined and genes associated with carbapenemases and extended-spectrum-beta-lactamases (ESBLs) were sequenced and compared with the closest representatives published in public domains. All strains were also sub-typed using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Statistical analyses were performed to determine the correlation between risk factors for acquiring carbapenem resistant K. pneumoniae and in-hospital mortality.ResultsThe predominant carbapenemase was blaOXA-48, detected in 12 strains (70.59%). Other carbapenemases detected in this study were blaKPC-2, blaIMP-8, blaNMC-A and blaNDM-1. Nine different pulsotypes were identified and nine strains which were affiliated with ST101, the predominant sequence type had similar PFGE patterns (similarity index of 85%). Based on univariate statistical analysis, resistance to imipenem and usage of mechanical ventilation showed a statistically significant effect separately to in-hospital mortality.ConclusionThe diverse genetic mechanisms harbored by these carbapenem resistant K. pneumoniae facilitates its spread and complicates its detection. Thus, correlation between microbiological trends with host characteristics and clinical factors will provide a better insight of rational treatment strategies and pathogen control.

Epidemiologic Patterns and Clinical Implications of Genotypic Resistance Mechanism for Carbapenem-Resistant Enterobacteriaceae (CRE)Surveillance Isolates from Los Angeles County

BackgroundCarbapenem-resistant Enterobacteriaceae (CRE), particularly carbapenemase-producing (CP) CRE, are an urgent public health threat. CRE with blaKPC have been most commonly reported, but blaNDM and other genotypes have epidemiologic and clinical significance. We seek to define epidemiologic patterns and antimicrobial susceptibility implications of genotypic resistance (R) mechanism in LAC.MethodsLAC Department of Public Health (DPH) Public Health Laboratory (PHL) conducted CRE laboratory surveillance of 31 clinical microbiology labs representing 34% (34/96) hospitals and 1 large regional lab serving 60% of SNFs from January 2015 to December 2016. Data on antimicrobial susceptibility testing (AST) was conducted by local laboratories and methodology varies by each submitting clinical lab. Isolates were sent to DPH PHL for identification of carbapenem resistance mechanism using Nanosphere Verigene BC-GN to detect carbapenemase genes; blaOXA, blaVIM, blaNDM, blaKPC, and blaIMP.ResultsDuring the study period, 843 CRE isolates were submitted to DPH for further analysis. CRE isolates were submitted from 34 hospitals (n = 604, mean 2 isolates/facility/month, range 1–7 isolates); 239 isolates submitted from regional SNF lab (range 2-54 isolates/month). Resistance mechanisms were identified in 684 Klebsiella spp., 61 E. coli, 45 Enterobacter spp., 10 Acinetobacter Baumannii, and other organisms. blaKPC was identified in 653 (77.5%) isolates, blaOXA in 17 (2%) isolates, and blaVIM in 2 isolates; 75 (9%) isolates did not have a marker detected. AST data and carbapenemase gene detection data were complete for 252 (30%) isolates, 250 isolates from hospitals and 2 SNF isolates; 29 isolates from hospitals were identified as pan-resistant, AST results for blaKPC differed from non-blaKPC isolates for tobramycin, amikacin, ciprofloxacin, aztreonam, ceftolazone tazobactam, ceftazidime avibactam (P < 0.05 for all).ConclusionCRE surveillance in a large urban setting continues to demonstrate that CRE Burden varies across individual facilities. Molecular epidemiology indicate that KPC remains the predominant carbapenemase, but NDM and other non-KPC mechanisms are recognized. Preliminary AST testing suggests that resistance mechanism has implications for antibiotic therapy.Disclosures All authors: No reported disclosures.

Risk factors for fecal carriage of carbapenemase producing Enterobacteriaceae among intensive care unit patients from a tertiary care center in India.

BackgroundResistance amongst the commensal flora is a serious threat because a very highly populated ecosystem like the gut, may at a later stage, be a source of extra intestinal infections, resistant strains may spread to other host or transfer genetic resistance element to other members of micro-biota including pathogens. This study was carried out to assess fecal colonization by carbapenemase producing Enterobacteriaceae (CPE) and associated risk factors among 100 patients admitted to intensive care unit (ICU). The phenotypic and molecular characterizations of CPE were also included.ResultsColonization with CPE was observed in 6.6 % (8/122) controls. Among ICU patients, fecal carriage of CPE was significantly higher on day 4 (D4) (22 %) as compared to day 1 (D1) (11 %) (p value 0.002). The carbapenemase genes detected included OXA- 48, 181, KPC and NDM-1 with NDM-1 being the predominant carbapenemase in both ICU D1 and D4. Among the 50 CPE isolates, 8 (16 %) were susceptible to meropenem and imipenem (Minimum inhibitory concentration; MIC ≤ 1 mg/L) and all were susceptible to colistin (MIC range 0.125 - 1 mg/L) and tigecycline (MIC range 0.06- 1.5 mg/L).The risk factors associated with CPE carriage were duration of ICU stay, use of ventilator and aminoglycosides.ConclusionsPrior colonization with CPE could result in their influx and spread in ICU, challenging infection control measures. Exposure to ICU further increases risk of colonization with diverse carbapenemase-producing Enterobacteriaceae. Gut colonization with these strains may be a source of endogenous infection and horizontal transfer of these genes in future.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-016-0763-y) contains supplementary material, which is available to authorized users.

Carbapenem Resistance in Gram-Negative Bacteria: The Not-So-Little Problem in the Little Red Dot.

Singapore is an international travel and medical hub and faces a genuine threat for import and dissemination of bacteria with broad-spectrum resistance. In this review, we described the current landscape and management of carbapenem resistance in Gram-negative bacteria (GNB) in Singapore. Notably, the number of carbapenem-resistant Enterobacteriaceae has exponentially increased in the past two years. Resistance is largely mediated by a variety of mechanisms. Polymyxin resistance has also emerged. Interestingly, two Escherichia coli isolates with plasmid-mediated mcr-1 genes have been detected. Evidently, surveillance and infection control becomes critical in the local setting where resistance is commonly related to plasmid-mediated mechanisms, such as carbapenemases. Combination antibiotic therapy has been proposed as a last-resort strategy in the treatment of extensively drug-resistant (XDR) GNB infections, and is widely adopted in Singapore. The diversity of carbapenemases encountered, however, presents complexities in both carbapenemase detection and the selection of optimal antibiotic combinations. One unique strategy introduced in Singapore is a prospective in vitro combination testing service, which aids physicians in the selection of individualized combinations. The outcome of this treatment strategy has been promising. Unlike countries with a predominant carbapenemase type, Singapore has to adopt management strategies which accounts for diversity in resistance mechanisms.

The Molecular Epidemiology and Genetic Environment of Carbapenemases Detected in Africa

Research articles describing carbapenemases and their genetic environments in Gram-negative bacteria were reviewed to determine the molecular epidemiology of carbapenemases in Africa. The emergence of resistance to the carbapenems, the last resort antibiotic for difficult to treat bacterial infections, affords clinicians few therapeutic options, with a resulting increase in morbidities, mortalities, and healthcare costs. However, the molecular epidemiology of carbapenemases throughout Africa is less described. Research articles and conference proceedings describing the genetic environment and molecular epidemiology of carbapenemases in Africa were retrieved from Google Scholar, Scifinder, Pubmed, Web of Science, and Science Direct databases. Predominant carbapenemase genes so far described in Africa include the blaOXA-48 type, blaIMP, blaVIM, and blaNDM in Acinetobacter baumannii, Klebsiella pneumoniae, Enterobacter cloacae, Citrobacter spp., and Escherichia coli carried on various plasmid types and sizes, transposons, and integrons. Class D and class B carbapenemases, mainly prevalent in A. baumannii, K. pneumoniae, E. cloacae, Citrobacter spp., and E. coli were the commonest carbapenemases. Carbapenemases are mainly reported in North and South Africa as under-resourced laboratories, lack of awareness and funding preclude the detection and reporting of carbapenemase-mediated resistance. Consequently, the true molecular epidemiology of carbapenemases and their genetic environment in Africa is still unknown.

Carbapenemase-producing Enterobacteriaceae in Sweden 2007-2013: Experiences from seven years of systematic surveillance and mandatory reporting.

Carbapenemase-producing Enterobacteriaceae (CPE) are increasing worldwide, and are a major threat to healthcare systems. Recent European data support that many countries have interregional spread of CPE or an endemic situation. In Sweden mandatory laboratory reporting of CPE of both colonisation and infection has been practiced since 2007 and since 2012 also by treating physicians. Between 2007 and 2013, 94 cases of CPE were detected in Sweden, out of which 24 were considered to cause clinical infections (bloodstream infection (n=4), urinary tract infection (n=12), wound infection (n=4), respiratory tract infection (n=2) and catheter related (n=2). The majority were detected in the hospital setting through faecal screening or as probable colonisers in clinical cultures. Travel abroad was observed in the majority of the patients (81%), and among them 84% had been hospitalised. During the study period only two chains of transmissions in Swedish hospitals were reported, involving four patients. Klebsiella pneumoniae was the primarily isolated species (n=57) followed by Escherichia coli (n=29). blaNDM was the predominant carbapenemase gene (n=36), followed by blaOXA-48-group, blaKPC and blaVIM. In 26/94 cases (28%) isolates were categorised as possible XDR (extensively drug-resistant). CPE are increasing in Sweden, but are still at a comparably low level.

Genetic and biochemical characterization of OXA-405, an OXA-48-type extended-spectrum β-lactamase without significant carbapenemase activity.

The epidemiology of carbapenemases worldwide is showing that OXA-48 variants are becoming the predominant carbapenemase type in Enterobacteriaceae in many countries. However, not all OXA-48 variants possess significant activity toward carbapenems (e.g., OXA-163). Two Serratia marcescens isolates with resistance either to carbapenems or to extended-spectrum cephalosporins were successively recovered from the same patient. A genomic comparison using pulsed-field gel electrophoresis and automated Rep-PCR typing identified a 97.8% similarity between the two isolates. Both strains were resistant to penicillins and first-generation cephalosporins. The first isolate was susceptible to expanded-spectrum cephalosporins, was resistant to carbapenems, and had a significant carbapenemase activity (positive Carba NP test) related to the expression of OXA-48. The second isolate was resistant to expanded-spectrum cephalosporins, was susceptible to carbapenems, and did not express a significant imipenemase activity, (negative for the Carba NP test) despite possessing a blaOXA-48-type gene. Sequencing identified a novel OXA-48-type β-lactamase, OXA-405, with a four-amino-acid deletion compared to OXA-48. The blaOXA-405 gene was located on a ca. 46-kb plasmid identical to the prototype IncL/M blaOXA-48-carrying plasmid except for a ca. 16.4-kb deletion in the tra operon, leading to the suppression of self-conjugation properties. Biochemical analysis showed that OXA-405 has clavulanic acid-inhibited activity toward expanded-spectrum activity without significant imipenemase activity. This is the first identification of a successive switch of catalytic activity in OXA-48-like β-lactamases, suggesting their plasticity. Therefore, this report suggests that the first-line screening of carbapenemase producers in Enterobacteriaceae may be based on the biochemical detection of carbapenemase activity in clinical settings.

Molecular characterization of carbapenem-resistant Enterobacteriaceae at a tertiary care laboratory in Mumbai.

Carbapenem-hydrolyzing β-lactamases are increasingly reported worldwide, leading to therapeutic failure. In an era where the drug development pipeline is stagnant, it is crucial to preserve current classes of antibiotics to help fight against infection caused by multidrug-resistant organisms (MDROs), by practicing a rational approach for the use of antibiotics. Identifying the mechanisms of resistance gives us much needed insights in this field. A total of 113 consecutive, non-duplicate carbapenem-resistant clinical isolates were collected from July to December 2012. These isolates were subjected to the modified Hodge test (MHT) for phenotypic detection of carbapenemases, an inhibitor-based test employing EDTA for the detection of metallo-β-lactamase (MBL), and phenylboronic acid for the detection of Klebsiella pneumoniae carbapenemase (KPC). A multiplex polymerase chain reaction (PCR) assay that characterized the five most predominant carbapenemases (bla NDM, bla OXA, bla VIM, bla IMP, bla KPC) was designed. The 113 isolates consisted of Klebsiella spp. (46), Enterobacter spp. (32), Escherichia coli (31), Citrobacter spp. (2), Proteus spp. (1), and Morganella spp. (1). bla NDM-1 was the most prevalent carbapenemase and accounted for 75.22% (85/113) of the isolates. This was followed by bla OXA [4.42% (n = 5)]. 18.5% (21/113) of the isolates possessed dual carbapenemase genes. 98.9% concordance was observed between the phenotypic tests and the molecular tests for the detection of MBL. In conclusion, patients infected with resistant bacteria require early appropriate antimicrobial treatment for good clinical outcome. Thus, identifying the resistant mechanisms of suspected pathogens becomes crucial. Also, the high incidence of plasmid-mediated bla NDM-1 calls for the implementation of strict infection control and contact isolation precautions in order to prevent the spread of these organisms.

Asymptomatic rectal carriage of blaKPC producing carbapenem-resistant Enterobacteriaceae: who is prone to become clinically infected?

Carbapenem-resistant Enterobacteriaceae (CRE) are emerging extremely drug-resistant pathogens; blaKPC is the predominant carbapenemase in Israel. Early detection of asymptomatic rectal carriers is important for infection control purposes. We aimed to determine who among newly identified CRE rectal carriers is prone to have a subsequent clinical specimen with CRE. A matched case-control study was conducted in a tertiary care teaching hospital in Israel. Cases with a primary positive CRE rectal test and subsequent CRE clinical specimens were matched in a 1:2 ratio with CRE rectal carriers who did not develop subsequent CRE clinical specimens (controls). Matching was based on calendar time of primary CRE isolation, whether the primary CRE isolation was ≤48 h or >48 h after hospital admission, and time at risk to have a subsequent clinical specimen. Data were extracted from the patients’ medical records and from the hospital’s computerized database. One hundred and thirty-two newly identified CRE rectal carriers (44 cases, 88 controls) were included. The median time interval between screening and subsequent clinical specimens was 11 days (range, 3–27); 86% of the clinical specimens were classified as true infections. Independent predictors of subsequent CRE clinical specimens were: admission to the intensive care unit, having a central venous catheter, receipt of antibiotics, and diabetes mellitus. Identification of the risk factors for subsequent infections among CRE-colonized patients can be used to control modifiable risk factors and to direct empirical antimicrobial therapy when necessary.

Prevalence and molecular epidemiology of acquired AmpC β-lactamases and carbapenemases in Enterobacteriaceae isolates from 35 hospitals in Spain

The purpose of this investigation was to determine the prevalence of plasmid-mediated AmpC (pAmpC) and carbapenemases in Enterobacteriaceae collected from 35 hospitals in Spain and to establish their epidemiological relationships. We conducted a prospective multi-centre study on pAmpC- or carbapenemase-producing Enterobacteriaceae isolates from clinical samples collected from February to July 2009. The strains suspected to carry pAmpC were resistant or showed intermediate susceptibility to co-amoxiclav and second- or third-generation cephalosporins. Strains suspected to carry a carbapenemase were selected because they showed a minimum inhibitory concentration (MIC) to imipenem >1 mg/L. Polymerase chain reaction (PCR) and a sequencing strategy were used to characterise the enzymes. The clonal relationships between isolates was analysed by pulsed field gel electrophoresis (PFGE). Among 100,132 Enterobacteriaceae isolates collected, 1,654 were compatible with the production of pAmpC or carbapenemases. We found a prevalence of 0.64 % of pAmpC (n = 635) and 0.04 % of carbapenemases (n = 43). The most prevalent pAmpC enzymes were CMY-type (78.3 %), DHA-type (19.5 %), ACC-type (1.6 %) and FOX-type (0.6 %). The CMY-type was the most frequent in Escherichia coli and Proteus mirabilis species, whereas the DHA-type was mainly found in Klebsiella spp. The enzymes involved in carbapenem resistance were VIM-1, IMP-22 and the new IMP-28. Nine new bla genes were described: bla (CMY-54), bla (CMY-55), bla (CMY-56), bla (CMY-57), bla (CMY-96), bla (DHA-6), bla (DHA-7), bla (FOX-8) and bla (IMP-28). The prevalence of pAmpC or carbapenemases found is not negligible. The CMY-types were the predominant pAmpC, whereas the VIM or IMP enzymes were the predominant carbapenemases. Furthermore, we observed a great genetic diversity among pAmpC-producing strains and a close clonal relationship between carbapenemase-producing strains.

High Prevalence of KPC-2-Type Carbapenemase Coupled with CTX-M-Type Extended-Spectrum β-Lactamases in Carbapenem-Resistant Klebsiella pneumoniae in a Teaching Hospital in China

Carbapenems such as imipenem and meropenem are the first-line agents for the treatment of serious nosocomial infections caused by multidrug-resistant Enterobacteriaceae clinical isolates (2). However, the phenomenon of carbapenem resistance is emerging among a wide variety of these species (11). Carbapenemases have been widespread in recent years and predominantly contribute to carbapenem resistance among Enterobacteriaceae, especially Klebsiella pneumoniae and Citrobacter freundi (8). For screening of the carbapenem-resistant Enterobacteriaceae clinical isolates, we conducted a surveillance study of carbapenem-resistant Enterobacteriaceae isolates in order to investigate the frequency and prevalence of K. pneumoniae carbapenemase (KPC)-type genes in Huashan Hospital (Fudan University, Shanghai, China), a 1,300-bed tertiary care hospital. We hereby report a high prevalence of carbapenem-resistant K. pneumoniae isolates carrying the KPC-2-type carbapenemase gene or KPC-2-type carbapenemase gene coupled with the CTX-M-type extended-spectrum β-lactamase (ESBL) gene. From January 2005 to March 2010, 109 nonduplicate Klebsiella pneumoniae isolates with resistance to ertapenem were collected. Antimicrobial susceptibility testing was performed by the agar dilution method, and MICs were interpreted following CLSI (4) or British Society for Antimicrobial Chemotherapy (BSAC) criteria (1). The presence of genes encoding β-lactamases, including metallo-β-lactamases (MBLs), KPC-type and OXA-type carbapenemases, ESBLs, and plasmid-mediated AmpC enzymes were screened by PCR using primers described by Rasheed et al. (10). All amplified products were then subjected to direct nucleotide sequencing. The results were analyzed with the software available on the National Center for Biotechnology Information website (http://www.ncbi.nlm.nih.gov). The susceptibility rates of 109 K. pneumoniae isolates to imipenem, meropenem, and ertapenem were 4.6%, 2.8%, and 0.0%, respectively (Table 1). Carbapenem-resistant Enterobacteriaceae isolates exhibited high resistance rates against the carbapenem agents tested, with MIC90 values of 128 μg/ml or higher. Totals of 96.3%, 74.3%, 66.1%, and 64.2% of isolates were susceptible to colistin, minocycline, tigecycline, and doxycycline, respectively (Table 1). KPC-2-type carbapenemase was the most predominant carbapenemase, present in 70.6% (77/109) of isolates. KPC-2-type carbapenemase coupled with CTX-M-14- or CTX-M-15-type ESBL accounted for 59.6% (65/109) of isolates. A total of 10.1% (11/109) of KPC-positive isolates were simultaneously producing both CTX-M-14-type ESBL and DHA-1-type plasmid-mediated AmpC enzymes. GIM-1-type or VIM-1-type MBL, OXA-type carbapenemases were detected in 9.2% (10/109) and 10.1% (11/109) of isolates, respectively. Table 1. Microbiological activities of various antimicrobial agents against 109 carbapenem-resistant K. pneumoniae isolates In this study, we have reported for the first time the frequency of KPC-2-type carbapenemases with or without CTX-M-type ESBLs among carbapenem-resistant K. pneumoniae isolates in China. In our hospital, the incidence of carbapenem-resistant K. pneumoniae isolates showed a significant increase from 0.9% in 2005 to 12.9% in 2009. These results suggested that the rapidly increased prevalence of carbapenem resistance among K. pneumoniae isolates in our hospital could be the consequence of the failure to control the spread of these strains. Therefore, prompt detection of carbapenemase-producing Enterobacteriaceae isolates, active antibiotic resistance surveillance, and strict implementation of infection control measures are critical to avoid the rapid spread or outbreaks by these multidrug-resistant or pan-drug-resistant isolates in health care-associated facilities (3, 5–7, 9).