Incidence and transferability of antibiotic resistance in the enteric bacteria isolated from hospital wastewater

This study reports the occurrence of antibiotic resistance and production of beta-lactamases including extended spectrum beta-lactamases (ES beta L) in enteric bacteria isolated from hospital wastewater. Among sixty-nine isolates, tested for antibiotic sensitivity, 73.9% strains were resistant to ampicillin followed by nalidixic acid (72.5%), penicillin (63.8%), co-trimoxazole (55.1%), norfloxacin (53.6%), methicillin (52.7%), cefuroxime (39.1%), cefotaxime (23.2%) and cefixime (20.3%). Resistance to streptomycin, chloramphenicol, nitrofurantoin, tetracycline, and doxycycline was recorded in less than 13% of the strains. The minimum inhibitory concentration (MIC) showed a high level of resistance (800-1600 mu g/mL) to one or more antibiotics. Sixty three (91%) isolates produced beta-lactamases as determined by rapid iodometric test. Multiple antibiotic resistances were noted in both among ES beta L and non-ES beta L producers. The beta-lactamases hydrolyzed multiple substrates including penicillin (78.8% isolates), ampicillin (62.3%), cefodroxil (52.2%), cefotoxime (21.7%) and cefuroxime (18.8%). Fifteen isolates producing ES beta Ls were found multidrug resistant. Four ES beta L producing isolates could transfer their R-plasmid to the recipient strain E. coli K-12 with conjugation frequency ranging from 7.0 x 10(-3) to 8.8 x 10(-)4. The findings indicated that ES beta L producing enteric bacteria are common in the waste water. Such isolates may disseminate the multiple antibiotic resistance traits among bacterial community through genetic exchange mechanisms and thus requires immediate attention.