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
Introduction: In this study, we investigated the presence of some beta-lactamases namely SHV, TEM and the most widely spread extended spectrum beta-lactamase (blaCTX-M-15) genes in E. coli isolated from four different bird species including ducks, pigeons, weaverbirds and bats in Ebonyi State, Nigeria. Methodology: Genes for ESBL production was determined based on PCR amplification of the genes encoding the enzymes including TEM, SHV and CTX-M-15 using specific primers. One hundred and fifty cloacal swabs each from ducks and pigeons and 100 each from weaverbirds and bats were respectively collected using sterile swab sticks. Antibiotic susceptibility test on the isolates was conducted using disc diffusion method while the phenotypic determination of ESBL was carried out using Double Disc Synergy Tests (DDST). Observations: Results from this study showed that E. coli was present in all the 4 bird species investigated. Of the 117 isolates screened for ESBL production, only 3(5.56 %) and 9(16.67 %), respectively were positive from ducks and pigeons while none was positive from bats and weaverbirds. Results of the molecular studies showed that the ESBL producing E. coli from pigeons were negative for SHV genes, positive for TEM and CTX-M-15 while those from ducks did not harbour any of the beta-lactamase and ESBL genes investigated. Conclusion: The detection of similar types of beta-lactamase and ESBL genes (TEM and CTX-M-15) in pigeon samples indicates the possible involvement of some bird species in the spread of multidrug resistant genes across human population. This is the first report of CTX-M-15 ESBL in bird species from Southeast Nigeria.
ABSTRACT
Background: Extended-spectrum β-lactamase (ESBL) producing uropathogens has become prevalent worldwide. E. coli O25b-ST131 clone, associated with blaCTX-M-15, has been reported from many parts of the world and is frequently associated with multidrug resistance. Thus far, there are no reports about this clone in Bangladesh. The objective of this study was to investigate ESBL producing uropathogens and to survey the prevalence of E. coli O25b-ST131 clone among ESBL positive E. coli isolates. Methods: From symptomatic urinary tract infection cases, a total of 800 urine samples were collected. Bacterial identification and antimicrobial susceptibility testing was performed using established methods. Screening of ESBL producers was done using the disk diffusion method. Screening positive isolates were phenotypically confirmed by double disk synergy (DDS) test. Genes encoding ESBLs (blaCTX-M-15, blaOXA-1) were identified both by PCR and DNA sequencing. Phenotypic positive ESBL producers were also studied by PCR for existence of class 1 integron. Subsequently, O25b-ST131 clone was identified by allele specific PCR. Results: Of 138 gram-negative uropathogens, 45 (32.6%) were positive for ESBLs. ESBL producers showed high frequency of antimicrobial resistance except imipenem. Among 45 ESBL producers, 36 (80%) produced blaCTX-M-15, 18 (40%) produced blaOXA-1. Fifteen (33.3%) strains simultaneously produced both blaOXA-1 and blaCTX-M-15. Class 1 integron was present in 30 (66.7%) isolates. Of the 31 blaCTX-M-15 positive E. coli, 22 (71%) were positive for E. coli O25b-ST131 clone and all (100%) belonged to B2 phylogenetic group. Conclusion: Rising antimicrobial resistance among uropathogens, and especially the emergence of blaCTX-M-15 positive E. coli O25b-ST131 clone in Bangladesh has provided urgency to the development of novel preventive and therapeutic strategies.