Use of norfloxacin in poultry production in the eastern province of Saudi Arabia and its possible impact on public health

Samples of market-ready chicken muscle and liver from 32 local broiler farm s were first screened for antibiotic residues by microbiological assay. The antibiotic-residue-positive muscles and livers from 22 farms were further analysed for norfloxacin (NFX) residues by high performance liquid chromato graphy. NFX was detected in 35.0% and 56.7% of raw antibiotic-residue-posit ive muscles and livers, respectively. The NFX-positive muscles and livers w ere respectively obtained from 11 (50.0%) and 14 (63.6%) of the 22 antibiot ic-residue-positive farms. Since the maximum residue limit (MRL) for NFX ha s not yet been fixed, the MRL for enrofloxacin was used in the study. All N FX-positive farms had mean raw tissue levels, which were 2.7- to 34.3-fold higher than the MRL. Although cooking markedly reduced NFX tissue concentra tions, mean detectable levels remained above MRL in large proportions of NF X-positive samples and farms. Susceptibility patterns of Enterobacteriaceae isolates from chicken and human patients to NFX showed alarmingly high rat es of resistance in chicken isolates especially among Escherichia coli (45. 9%) and Pseudomonas spp. (70.6%) compared with patients' isolates (10.5% an d 18.2%, respectively). The study reveals widespread misuse of NFX in the l ocal poultry industry, which may pose a major risk to public health includi ng possible stimulation of bacterial resistance and hypersensitivity reacti ons to fluoroquinolones. More prudent use of fluoroquinolones in food-produ cing animals is therefore recommended. Further, there is a need to establis h MRL values for NFX.