Detection of antimicrobial resistance genes and phylogenetic groups of escherichia coli isolated from poultry
Abstract
The present study was conducted to determine antimicrobial resistance pattern of E. coli isolates, prevalence and characterization of Class I integrons in the E. coli isolates and to identify the phylogenetic group(s) of the E. coli isolates from poultry. The data of each flock was analyzed for morbidity, mortality and case fatality rate (CFR). E. coli isolates (106) were collected, identified and were subjected to in vitro antibiotic sensitivity test. The isolates were assigned to different phylogenetic groups and analysed for presence of Class 1 integrons using PCR. Mean morbidity, mortality and CFR was 3.83±0.37%, 2.29±0.25% and 0.55±0.01 respectively. Nine (8.49%), 2 (1.89%), 85 (80.19%) and 10(9.43%) isolates belonged to phylogenetic group A, B1, B2 and D, respectively. All the isolates were resistant to at least five antibiotics out of 16, which indicates that 100% isolates were multi drug resistant (MDR). Antimicrobial susceptibity pattern indicated maximum resistance towards bacitracin and least towards chloramphenicol. There was no significant difference between resistance to different antimicrobials and phylogenetic group affiliation in the present study, 37 (34.90%) were found positive for class 1 integrons. The size of PCR product varied form ~720bp to ~2.8kb. A maximum of 17 (16.04%) isolates were found to be harbouring Class 1 integrons of size >1.0 kb to 1.5 kb followed by 8 (7.55%) of size >1.5 kbto 2.0 kb, 5 (4.72%) of size≤1.0 and 4 (3.77%) of size >2.0 to 3.0 kb. The PCR products of three isolates revealed multiple Class 1 integrons (two in number). Total number of Class 1 integrons amplified was 40.Asthere was significant difference in phylogenetic group distribution between isolates with class 1 integrons and those without the integrons in group A. Analysis of E. coli isolates resistant to different antimicrobials in relation to their carriage of Class I integron revealed that out of 59 isolates resistant to co-trimoxazole 28 (47.5%) were carrying integrons. Least carriage of Class 1 integrons was observed in isolates resistant to ceftriaxone (18/63, 28.6%). A significant difference was observed between the class 1 integron carrying isolates and isolates not carrying class 1 integrons for their resistance to co-trimoxazole in the present study.
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