Faculty of Veterinary Medicine University of Zagreb
Abstract
Escherichia coli and Staphylococcus aureus species though opportunist pathogens, are becoming a global clinical problem in both human and veterinary medicine. This study was designed to determine the antibiotic susceptibility patterns of β-lactamase-producing E. coli serotypes and S. aureus strains isolated from chickens in the Maiduguri Arid zone, Nigeria. Various tissue samples from apparently healthy and diseased chickens were collected and examined for the presence of E. coli and S. aureus. Isolates were identified by relevant biochemical tests. β-lactamase-producing strains of the isolates were determined by the chromogenic cephalosporin method, using nitrocefin-impregnated sticks and cephalosporin (nitrocefin) solution. The antibiotics susceptibility patterns of the isolates were determined for ten antibiotics (ampicillin, chloramphenicol, cephalexin, ciprofloxacin, lincomycin, doxycycline, tetracycline, tylosin, tylosin tartrate and penicillin) by the micro-broth
dilution method. E. coli was isolated in 805 and S. aureus in 660 of 1300 tissue samples examined; from which 89 (11.1%) and 58 (8.8%) were β-lactamase-positive isolates respectively. Out of 540 E. coli isolates serotyped, 57 (10.6%) serogroups were identified from which 17 (29.8%) were serogroups O1, 5 (8.8%) were O2, and 2 (3.5%), 9 (15.8%), 6 (10.5%) and 18 (31.6%) were serogroups O26, O78, O86 and O141 respectively, whilst, 483 (89.4%) isolates were not typable with the available sera. Serogroups O141, O1 and O78 were more frequently isolated and serogroups O1 and O78 were more prevalent in sick chickens than in healthy chickens. E. coli exhibited high resistance to ampicillin, chloramphenicol, tetracycline, lincomycin, penicillin and tylosin with MIC values >8.0 μg/mL, as did S. aureus to all the antibiotics tested with MIC values >8.0 μg/mL. In conclusion, the study has demonstrated the presence of E. coli serotypes and S. aureus in various tissues of
chickens and their antibiotic susceptibility patterns, clearly demonstrating multiple drug resistance.Premda uvjetno patogene vrste Escherichia coli i Staphylococcus aureus predstavljaju globalni klinički problem u humanoj i veterinarskoj medicini. Ovo istraživanje provedeno je sa svrhom određivanja osjetljivosti prema antibioticima serovarova E. coli i izolata S. aureus izdvojenih iz pilića u sušnom području Maiduguri u Nigeriji. Različiti uzorci tkiva od naizgled zdravih te od bolesnih pilića bili su pretraženi na prisutnost bakterija E. coli i S. aureus. Izolati su bili identificirani različitim biokemijskim testovima. Sojevi što su proizvodili β-laktamazu bili su identificirani kromogen cefalosporinskom metodom uz uporabu nitrocefinom impregniranih stikova i otopine cefalosporina (nitrocefina). Osjetljivost spomenutih bakterija bila je određivana mikrodilucijskom metodom na 10 antibiotika (ampicilin, kloramfenikol, cefaleksin, ciprofloksacin, linkomicin, doksiciklin, tetraciklin, tilozin, tilozin tartarat i penicilin). E. coli je bila izdvojena iz 805, a S. aureus iz 660 od
1300 pretraženih uzoraka tkiva od čega je 89 (11,1%) izolata E. coli i 58 (8,8%) izolata S. aureus bilo pozitivno na β-laktamazu. Od 540 serološki tipiziranih izolata E. coli identificirano je bilo 57 (10,6%) seroloških skupina od čega je 17 (29,8%) pripadalo serološkoj skupini O1, 5 (8,8%) serološkoj skupini O2, 2 (3,5%) skupini O26, 9 (15,8%) skupini O78, 6 (10,5%) skupini O86 i 18 (31,6%) serološkoj skupini O141, dok se 483 (89,4%) izolata nisu mogla tipizirati raspoloživim antiserumima. Najčešće su bile izdvojene serološke skupine O141, O1 i O78 s time da su serološke skupine O1 i O78 prevladavale u bolesnih pilića. E. coli je bila vrlo otporna na ampicilin, kloramfenikol, tetraciklin, linkomicin, penicilin i tilozin s vrijednostima minimalne inhibitorne koncentracije >8,0 μg/mL. I S. aureus je bio otporan prema svim pretraživanim antibioticima s minimalnim inhibitornim vrijednostima >8,0 μg/mL. U istraživanju je dokazana prisutnost serovarova E. coli i vrste S. aureus u različitim tkivima pilića te njihova osjetljivost na antibiotike s jasno dokazanom multiplom rezistencijom
