Antibiotic-resistant Escherichia coli from goat farms and the potential treatment by Acalypha indica L. extract

Abstract

Antibiotics have been used in both human and animal therapeutics. The present study aimed to investigate antibiotic resistance in E. coli isolated from goats. The antimicrobial susceptibility testing (AST) in these isolates was performed using broth microdilution. From 86 E. coli isolates, 2, 1, and 6 isolates were resistant to imipenem, ciprofloxacin, and colistin, respectively. Only one isolate could analyze the whole-genome of antibiotic-resistant E. coli. It was strain Y5.4.5 and by the MLST revealed that it belonged to ST345. This isolate harbored several antibiotic-resistant genes, including aadA1, aadA2, blaTEM-1B, cmlA1, dfrA12, floR, qnrS1, sul1, sul2, sul3, tet(A), conferring resistance to streptomycin, ampicillin, chloramphenicol, trimethoprim, ciprofloxacin I/R, sulfisoxazole, tetracycline. The Inc and Col-like plasmids were also identified in the isolate. There kinds of herbal, Cinnamomum porrectum (Roxb.) Kosterm, Caesalpinia bonduc and Acalypha indica L. were selected for extraction and analyzed the activity against antibiotic-resistant E. coli. The ethanol crude extract of A. indica L. could inhibit E. coli growth with the MIC of 25 mg/ml. The time-kill assay revealed that the crude extract started its inhibition activity at 4 h. It was less bactericidal but bacteriostatic was found. Our study presents the whole genome of antibiotic-resistant E. coli strain Y5.4.5 isolated from goats, and the A. indica L. extract might be combined with other antibiotics or herbal extracts as alternative medicine.