ABSTRACT
Objective@#To analyze the molecular epidemiological characteristics of Escherichia coli producing NDM-5 carbapenemase in the neonatal department of our hospital. @*Methods@#Three carbapenem-resistant Escherichia coli strains（E1, E2 and E3） isolated from neonatal ward of our hospital from August to September of 2017 were collected. Vitek 2 Compact system combined with K-B disk method was used for drug sensitivity test. The resistance genes were detected by PCR amplification. Plasmid replicon typing was detected by PCR. Plasmid conjugation tests were performed to explore the conjugating transfer of plasmids in the three strains. The homology of the three strains was analyzed by multiple locus sequence typing (MLST) and pulse field gel electrophoresis (PFGE). @*Results@#Drug susceptibility test showed that the three bacteria were resistant to most β-lactam antibiotics except Aztreonam, and resistant to quinolones and SMZ-TMP, but sensitive to aminoglycosides drugs. PCR and sequencing results indicated that the three strains carried bla SHV gene and extended-spectrum beta-lactamase gene (bla SHV , bla TEM and bla CTX-M ). The plasmid replicon type was IncX3. Transfer test of E1 strain was successful. MLST results indicated that all the three strains were ST1642 type. MLST and PFGE results indicated that the bands of the three bacteria were identical. @*Conclusion@#Both NDM-5 carbapenemase and extended-spectrum beta-lactamase were detectable in the three strains of carbapenem-resistant bacteria from neonatal department. MLST and PFGE results suggested that the three strains were from the same clonal source.
ABSTRACT
ObjectiveThe nucleic acid technology for detecting drug-resistant genes has become one of the powerful tools for monitoring and controlling the spreading of drug-resistant bacteria. This study was to establish a method for rapid detection of the drug-resistant genes KPC and NDM and provide some guidance in clinical drug use and monitoring the prevalence of drug-resistant bacteria in the hospital.MethodsAccording to the conserved regions of Klebsiella pneumoniae carbapenemase (KPC) and New Delhi metallo-β-lactamase (NDM), we designed the primers of duplex PCR, optimized the amplification system and established a method for simultaneous detection of the drug-resistant genes KPC and NDM. Then, we analyzed the sensitivity and specificity of the method and applied it to the detection of Pseudomonas aeruginosa and Klebsiella pneumoniae.ResultsThe sequences of KPC and NDM exhibited a 100% consistency with those of the original ones. Target fragments of the desired size of 151 bp were detected in the KPC-2 positive standard and Klebsiella pneumoniae ATCC BAA 1705 standard strains, and those of the desired size of 261 bp were observed in the NDM-2 positive standard strain and NDM-positive pneumococcal bacteria, neither with non-specific amplification. Sequencing of the PCR products showed a 100% consistency between the sequences of the products and those of the drug-resistant genes KPC-2 and NDM-1. The detectable limits of KPC and NDM for duplex PCR were 7×102 and 5×102 copies per reaction respectively. Drug-resistant genes were detected in 12 (92.3%) of the 13 carbapenems-resistant strains, including 10 KPC-positive (83.3%) and 2 NDM positive ones (16.7%), but neither KPC nor NDM in the other 10 carbapenems-sensitive strains. In the 13 strains of Pseudomonas aeruginosa, KPC was detected in 2 (33.3%) of the 6 carbapenems-resistant ones, but neither KPC nor NDM in the other 7.ConclusionThe duplex PCR method can be used for rapid and effective detection of the drug-resistance genes KPC and NDM, with the advantages of high sensitivity and specificity, and is therefore of great significance for guiding clinical drug use and monitoring the spreading of carbapenems-resistant bacteria in the hospital.
ABSTRACT
In this study, we evaluated the coexistence of extended‑spectrum beta‑lactamases (ESBL), AmpC and New Delhi metallo‑beta‑lactamase‑1 (NDM‑1) genes among carbapenem‑resistant Enterobacteriaceae (CRE) recovered prospectively from patients at multiple sites. The study included 285 CRE strains from 2782 Gram‑negative Bacilli collected from multiple centres during 2007–2010, of which 87 were characterised. Standard and reference laboratory methods were used for resistance determination. Detection of blaNDM‑1, blaAmpC, blaTEM, blaSHV and blaCTX‑M was done by polymerase chain reaction. High levels of antimicrobial resistance observed among study isolates. Co‑carriage of ESBLs, AmpC and NDM‑1 was 26.3%. Nosocomial origin among the co‑carriage isolates was 64.3%, with 9.2% associated mortality.
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Purpose: blaNDM genes are MBL genes that confer resistance to carbapenems. Globally, they are associated with diverse clones and plasmids. In this study, we characterised three isolates of Klebsiella pneumoniae‑harbouring blaNDM1 from patients undergoing chronic haemodialysis and renal transplantation. Materials and Methods: 3 blaNDM1‑producing K. pneumoniae were isolated from end‑stage renal disease patients undergoing haemodialysis and renal transplantation from a nephrology unit. All the three isolates were screened for clinically relevant resistant genes. Plasmid replicon content was analysed by polymerase chain reaction based replicon typing. Conjugation assays were done using azide‑resistant Escherichia coli J53 as the recipient strain. Multilocus sequence typing and variable number tandem repeat typing were done to find the clonality. Replicon sequence based typing was attempted to find the diversity of replicon‑associated sequences in IncHI3 plasmids. Results: All the 3 blaNDM positive isolates possessed the New Delhi metallo‑beta‑lactamase‑1 (NDM‑1) allele with an IncHI3 plasmid which was not transferable in one isolate. The isolates were found to be sequence type 14 (ST14; 2 nos) and ST38 both of which were previously reported to be the NDM‑producing K. pneumoniae STs prevalent in India. Replicon sequence analysis revealed limited sequence diversity within the repHI3 and repFIB locus. Conclusion: To the best of our knowledge, this is the first report of IncHI3, a newly assigned enterobacterial plasmid incompatibility group from India. This could either be a case of importation or a widely circulating NDM plasmid type in India.
ABSTRACT
Purpose: Increasing reports on New Delhi metallo-β-lactamase-1 (NDM-1) producing Escherichia coli constitute a serious threat to global health since it is found to be highly resistant to most of the currently available antibiotics including carbapenems. This study has been performed to find out the incidence blaNDM-1 in E. coli isolates recovered from the various clinical samples at a tertiary care referral hospital in Northeast India. Materials and Methods: A total of 270 non-duplicated E. coli isolates were recovered from the various clinical samples at a tertiary care referral hospital in Northeast India. All isolates with reduced susceptibility to meropenem or ertapenem (diameter of zones of inhibition, ≤21 mm) were further phenotypically confirmed for carbapenemase production by modified Hodge test. All screened isolates were also subjected to the polymerase chain reaction detection of blaNDM-1 gene and additional bla genes coding for transmission electron microscopy, SHV, CTX-M, and AmpC. Results: Out of 270 E. coli isolates, 14 were screened for carbapenemase production on the basis of their reduced susceptibility to meropenem or ertapenem. All screened isolates were found to be positive for blaNDM-1 . Each of the blaNDM-1 possessing isolate was also positive for two or more additional bla genes, such as blaTEM , blaCTX-M and blaAmpC . Phylogenetic analysis showed very less variation in blaNDM-1 gene with respect to blaNDM-1 possessing E. coli isolates from other parts of India and abroad. Conclusions: Our findings highlight the incidence of blaNDM-1 in E. coli isolates with a reduced susceptibility to meropenem or ertapenem.
ABSTRACT
The world has seen the emergence of many micro-organisms in the recent past, which can curb human population with their newly built genetic make-up. The latest addition to this list of panic creating organisms is, bacteria encoding the gene for New Delhi metallo-beta-lactamase (NDM-1). NDM-1 is an enzyme that can hydrolyze and inactivate carbapenems, which are used as a last resort for the treatment of multi-resistant bacterial infections. Names of these bacteria were not found in the medical literature before December 2009, because of which it can take the credit of becoming a powerful emerging bacteria, which are difficult to treat. Besides Escherichia coli and Klebsiella pneumoniae, other bacterial strains have also expressed the gene for NDM-1, which are detected in many countries.