Antibioresistance of Escherichia coli strains isolated in Morocco from chickens with colibacillosis.

Two hundred and fifty eight isolates of Escherichia coli were made from autopsied chickens showing lesions of avian colibacillosis. Antibiograms showed high levels of resistance (greater than 40%) to sulphonamides (SSS), oxytetracycline (OT), trimethoprim + sulphamethoxazole (STX) and chloramphenicol (C). Medium frequencies of resistances (from 15 to 40%) were noted for streptomycin (S), spectinomycin (SPT), nalidixic acid (NA), oxolinic acid (OA), flumequine (UB) and enrofloxacine (ENR). For ampicillin (AM), gentamicin (GM), nitrofurans (FT), colistin (CS) and rifampin (RA) the frequencies of resistance were low (less than 15%). A linked resistance was observed for the 4 quinolones. A significant percentage of isolates (82.5%) were resistant to at least 2 antimicrobial agents. The most frequent antibiotypes were: C.OT.SSS.STX (4.65%), C.OT.SSS.STX.OA.NA.UB.ENR (4.65%), AM.S.C.OT.SSS.STX (4.26%) and OT.SSS.STX (3.87%).