Shakya, Dr. SanjayNADIPILLI SRILAKSHMI2024-07-092024-07-092024-02https://krishikosh.egranth.ac.in/handle/1/5810211665Antimicrobial resistance (AMR) is one of the top 10 global public health threats, resulting in the progressive loss of antimicrobials efficacy making infections harder to treat thereby increasing the risk of disease spread, severe illness and death. Antibiotics are widely used in the poultry sector for therapeutic purposes, prophylaxis, metaphylaxis and as growth promoters is which makes commensal bacteria such as E. coli to develop resistance against those drugs, the emergence and spread of AMR are closely related to this. Antibiotic resistant E. coli which is an important reservoir of ARGs often released into environment through feces and further air borne spread may occur leading to wider distribution of AMR. The present study was undertaken to investigate the airborne dissemination of antibiotic resistant genes (ARGs) through E. coli, in poultry farms. A total of 120 samples (90 air, 15 poultry feces and 15 dust samples) were collected from 5 poultry farms in and around Durg district in Chhattisgarh and analyzed for the isolation and identification of E. coli by conventional cultural techniques and further confirmed by biochemical tests and molecular techniques. All E. coli isolates were subjected to antibiotic susceptibility test against 12 antibiotics to know their antibiogram pattern. Prevalence of Extended Spectrum Beta-Lactamae (ESBL) genes (blaCTX-M, blaSHV, blaTEM) and other resistance genes (tetA, tetB, gyrA and parC) among E. coli isolates were also determined. Enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) was done to assess the source of airborne spread. A total of 55 (45.83%) samples were found positive for E. coli among 120 samples analyzed. A total of 109 E. coli isolates were recovered, which include 53, 30 and 15 isolates from air (27), feces (15) and dust (13) samples, respectively. All isolates were genotypically confirmed by PCR – based molecular method by targeting 16S rRNA gene. E. coli isolates recovered from all samples showed maximum resistance against cephalexin (95.41%) and oxytetracycline (87.15%). MAR index for all E. coli isolates varied between 0.08 to 0.91. Among total 96 MDR E. coli isolates, 76 (79.17%) were phenotypically positive for ESBL production and 74 (77.08%), 13 (13.54%) and 3 (3.15%) isolates harboured blaTEM, blaCTX-M and blaSHV genes, respectively. Out of 46 E. coli isolates recovered from air, 34 (73.91%), 3 (6.52%) and 1(2.17%) isolate harboured blaTEM, blaCTX-M and blaSHV genes, respectively. Among total 95 tetracycline resistant E. coli isolates, 93 (97.89%) and 2 (2.11%) isolates harboured tetA and tetB genes, respectively. Out of 45 tetracycline resistant E. coli isolates recovered from air, 45 (100%) and 2 (4.44%) harboured tetA and tetB genes respectively. Among total 76 fluoroquinolone resistant isolates, 72 (94.73%) and 73 (96.05%) isolates harboured gyrA and parC genes, respectively. Out of 39 fluoroquinolone resistant E. coli isolates recovered from air, 38 (97.43%) harboured both gyrA and parC genes. ERIC-PCR analysis revealed similarity in the range of 25-80% among air, fecal and dust isolates indicating presence of genomically diverse population of E. coli in farms under study. Extensive use of antibiotics for disease prevention and growth promotion apart from therapeutic uses may be attributed to the higher prevalence of ARGs. Close surveillance and monitoring of use of antibiotics in poultry production should be done to reduce the development of antibiotic resistance.EnglishThesis