Broiler Poultry Farms in Negros Occidental as Potential Reservoirs of Multidrug- and Colistin-Resistant Coliforms

MDR coliforms have become an increasing and consistent problem in human and animal health nowadays. The overuse of antibiotics, whether in a clinical setting or in animal farming, has been a contributing factor to the emergence of MDR organisms capable of producing ESBL, ampC, and even resisting colistin. The current study was made to detect and isolate MDR coliforms, including those that produce ESBL, ampC, and those that can resist the antibiotic colistin from chicken droppings in two poultry farms in Negros Occidental, Philippines. A total of 120 fecal swabs were analyzed using conventional microbiologic methods, Kirby-Bauer disc diffusion method for antimicrobial susceptibility, and disc broth elution for colistin resistance. ESBL and AmpC were detected using double disk synergy test. Multiple Antibiotic Resistance Index (MARI) was calculated as the ratio between the number of antibiotics that an isolate is resistant to and the total number of antibiotics it was tested for. Out of 120 samples, 62 (51.67%) were identified as E. coli, 18 (15%) as K. pneumoniae, and 2 (1.67%) as E. cloacae. Most of the isolates were resistant to chloramphenicol (85.37%), amoxicillin/clavulanic acid (74.39%) and colistin (69.51%). Moreover, ESBL production was noted in 23 isolates (28.05%), AmpC in 2 isolates (2.44%) with a mean MARI of 0.39, indicating that these organisms originated from high-risk environments. The findings of this study reveal the emerging threats of MDR coliforms in poultry production. It is therefore important for public health authorities to minimize, if not prevent, the potential risk of spreading these MDR coliforms from poultry farms.