ABSTRACT
Purpose: The present study was aimed to investigate the genetic context, association with IS26 and horizontal transmission of SHV‑148 among Escherichia coli in Tertiary Referral Hospital of India. Methodology: Phenotypic characterisation of extended‑spectrum beta‑lactamases (ESBLs) was carried out as per CLSI criteria. Molecular characterisation of blaSHV and integron was carried out by polymerase chain reaction (PCR) assay and confirmed by sequencing. Linkage of IS26 with blaSHV‑148 was achieved by PCR. Purified products were cloned on pGEM‑T vector and sequenced. Strain typing was performed by pulsed field gel electrophoresis with XbaI digestion. Transferability experiment and antimicrobial susceptibility was performed. Results: A total of 33 isolates showed the presence of SHV‑148 variant by sequencing and all were Class 1 integron borne. PCR and sequencing results suggested that all blaSHV‑148 showed linkage with IS26 and were present in the upstream portion of the gene cassette and were also horizontally transferable through F type of Inc group. Susceptibility results suggest that tigecycline was most effective. Conclusion: The present study reports for the first time of SHV‑148 mediated extended spectrum cephalosporin resistance from India. Association of their resistance gene with IS26 and Class 1 integron and carriage within IncF plasmid signifies the potential mobilising unit for the horizontal transfer.
ABSTRACT
Background & objectives: Pseudomonas extended resistant (PER) enzymes are rare type of extended-spectrum beta lactamases (ESBLs) that confer third generation cephalosporin resistance. These are often integron borne and laterally transmitted. The aim of the present study was to investigate the emergence of integron borne cephalosporin resistant PER-1 gene in diverse incompatibility (Inc) group plasmids among gram-negative bacteria. Methods: a total of 613 consecutive, non-duplicate, Gram-negative bacteria of Enterobacteriaceae family and non-fermenting Gram-negative bacteria were isolated from different clinical specimens during a period of 18 months. For amplification and detection of blaPER, multiplex PCR was done. For understanding the genetic environment of blaPER-1, integrase gene PCR and cassette PCR (59 be) was performed. Gene transferability experiment was carried out and PCR based replicon typing was performed for incompatibility group typing of plasmids using 18 pairs of primers. An inhibitor based method was used for phenotypic detection of intrinsic resistance. Results: Multiplex PCR and sequencing confirmed that 45 isolates were harbouring blaPER-1. Both class 1 and class 2 integrons were observed among them. Integrase and cassette PCR (59 be) PCR results confirmed that the resistant determinant was located within class 1 integron. Transformation and conjugation experiments revealed that PER-1 was laterally transferable and disseminated through diverse Inc plasmid type. Efflux pump mediated carbapenem resistance was observed in all isolates. All isolates belonged to heterogenous groups. Interpretation & conclusions: This study demonstrates the dissemination of cephalosporins resistant, integron borne blaPER-1 in hospital setting in this part of the country and emphasizes on the rational use of third generation cephalosporins to slow down the expansion of this rare type of ESBL gene.