Presence of fluoroquinolone-resistant coliforms in poultry litter

Litter was collected from four turkey farms (eight houses) with a history o f fluoroquinolone (FQ) treatment failure, 10 adult broiler breeder chicken farms (43 houses) with one having a history of FQ treatment, and 30 broiler chicken farms (110 houses) with 24 having a history of FQ treatment. In th e turkey litter, the percentage of nalidixic acid-resistant tar 100 mug/ml) coliforms/total number of coliforms ranged from 0.6% to 61.9%. Two of the four farms had houses containing coliforms resistant to the two FQs, enrofl oxacin (1 mug/ml) and sarafloxacin (1 mug/ml). There was also multiple resi stance to other antimicrobials on all four turkey farms (ampicillin, tetrac ycline, chloramphenicol, kanamycin). The level of total coliforms from the adult broiler breeder litter was low, and there were no nalidixic acid-resi stant isolates from any of the 10 farms. In the broiler chickens, 7 of 91 h ouses with a history of FQ usage contained coliforms resistant to nalidixic acid; however, 2 of the 19 houses on farms with no history of FQ usage had nalidixic acid-resistant coliforms. All of the broiler farms with nalidixi c acid-resistant isolates were also resistant to the FQ sarafloxacin, where as only 3 of the 24 treatment history farms and 1 of the no-treatment histo ry farms exhibited enrofluxacin-resistant coliforms in the litter.