Minimum inhibitory concentration

The distribution of resistance to ampicillin, penicillin, erythromycin, tetracycline, and amoxicillin among Gram negative bacteria in the hospital wastewater samples was investigated. The emergence of resistance among the Gram negative bacterial population varied considerably in different drug and water sampling sites. Gram negative bacteria showed lower drug resistant viable count (1.23x104-7.0x102) in site-II (receiving treated wastewater), as compared to more polluted site-I (1.28x104-5.0x102), III (2.22x104-5.0x102) and site-IV (1.63 x104-2.0 x102) respectively. Viable counts of Gram negative bacterial population were recorded higher against erythromycin from sampling site-III. Lower viable counts of Gram negative bacteria were recorded against tetracycline in site-I and IV. Percentage MIC of antibiotic among the isolates observed higher in tetracycline and erythromycin than the other antibiotics. Isolates of Gram negative bacteria showed their tolerance level (MIC) in the range of 2.5-640μg/ml against the antibiotics. Maximum number of isolates exhibited their MICs at lower concentration range 2.5-5μg/ml against tetracycline. A few number of isolates also showed their MIC at lower concentration of other antibiotics tested from all the sampling sites.