ABSTRACT
Background & objectives: Bacillary dysentery caused by Shigella spp. remains an important cause of the crisis in low-income countries. It has been observed that Shigella species have become increasingly resistant to most widely used antimicrobials. In this study, the antimicrobial resistance, virulence and plasmid profile of clinical isolates of Shigella species were determined. Methods: Sixty clinical Shigella isolates were subjected to whole-genome sequencing using Ion Torrent platform and the genome sequences were analyzed for the presence of acquired resistance genes, virulence genes and plasmids using web-based software tools. Results: Genome analysis revealed more resistance genes in Shigella flexneri than in other serogroups. Among ?-lactamases, blaOXA-1was predominantly seen followed by the blaTEM-1B and blaEC genes. For quinolone resistance, the qnr S gene was widely seen. Novel mutations in gyr B, par C and par E genes were observed. Cephalosporins resistance gene, blaCTX-M-15 was identified and plasmid-mediated AmpC ?-lactamases genes were found among the isolates. Further, a co-trimoxazole resistance gene was identified in most of the isolates studied. Virulence genes such as ipaD, ipaH, virF, senB, iha, capU, lpfA, sigA, pic, sepA, celb and gad were identified. Plasmid analysis revealed that the IncFII was the most commonly seen plasmid type in the isolates. Interpretation & conclusions: The presence of quinolone and cephalosporin resistance genes in Shigella serogroups has serious implications for the further spread of this resistance to other enteric pathogens or commensal organisms. This suggests the need for continuous surveillance to understand the epidemiology of the resistance.
ABSTRACT
Background & objectives: Plasmid has led to increase in resistant bacterial pathogens through the exchange of antimicrobial resistance (AMR) genetic determinants through horizontal gene transfer. Baseline data on the occurrence of plasmids carrying AMR genes are lacking in India. This study was aimed to identify the plasmids associated with AMR genetic determinants in ESKAPE pathogens. Methods: A total of 112 ESKAPE isolates including Escherichia coli (n=37), Klebsiella pneumoniae (n=48, including 7 pan-drug susceptible isolates), Acinetobacter baumannii (n=8), Pseudomonas aeruginosa (n=1) and Staphylococcus aureus (n=18) were analyzed in the study. Isolates were screened for antimicrobial susceptibility and whole genome sequencing of isolates was performed using Ion Torrent (PGM) sequencer. Downstream data analysis was done using PATRIC, ResFinder, PlasmidFinder and MLSTFinder databases. All 88 whole genome sequences (WGS) were deposited at GenBank. Results: Most of the study isolates showed resistant phenotypes. As analyzed from WGS, the isolates included both known and unknown sequence types. The plasmid analysis revealed the presence of single or multiple plasmids in the isolates. Plasmid types such as IncHI1B(pNDM-MAR), IncFII(pRSB107), IncFIB(Mar), IncFIB(pQil), IncFIA, IncFII(K), IncR, ColKP3 and ColpVC were present in K. pneumoniae. In E. coli, IncFIA, IncFII, IncFIB, Col(BS512), IncL1, IncX3 and IncH were present along with other types. S. aureus harboured seven different plasmid groups pMW2 (rep 5), pSAS1 (rep 7), pDLK1 (rep 10), pUB110 (rep US12), Saa6159 (rep 16), pKH12 (rep 21) and pSA1308 (rep 21). The overall incidence of IncF type plasmids was 56.5 per cent followed by Col type plasmids 18.3 per cent and IncX 5.3 per cent. Other plasmid types identified were <5 per cent. Interpretation & conclusions: Results from the study may serve as a baseline data for the occurrence of AMR genes and plasmids in India. Information on the association between phenotypic and genotypic expression of AMR was deciphered from the data. Further studies on the mechanism of antibiotic resistance dissemination are essential for enhancing clinical lifetime of antibiotics.
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.