Killing Rate Kinetics of Commercially Available Brands of Ciprofloxacin and Cefotaxime on Clinical Bacterial Isolates Subjected to in vitro Antibiotic Treatments

摘要

The objective of this study was to determine the killing rate kinetics of commercially available brands of ciprofloxacin and cefotaxime on clinical isolates of Salmonella spp and Escherichia coli subjected to in vitro antibiotic treatments. One hundred and fifty (150) midstream urine samples were collected from urinary tract infection (UTI) patients attending Federal Teaching Hospital Abakaliki. Exactly 82 bacterial species (52 E. coli and 30 Salmonella species) were isolated from the urine samples after standard microbiological analysis. Time curve assay was done to determine the antibacterial activities of different company brands of ciprofloxacin and cefotaxime against Salmonella species and Escherichia coli using a sequential treatment scheme. Identified E. coli and Salmonella spp isolates were highly susceptible to meropenem, gentamicin, and ciprofloxacin but resistant to cefotaxime, ceftriaxone, and trimethoprim. Average MARI values of 0.4 and 0.2 were observed for E. coli and Salmonella spp respectively. Killing rate kinetics results showed that at 0 initial hour incubation without antibiotics, bacterial colonies were too numerous to count (TNTC). The growth of colonies when ciprofloxacin B and cefotaxime E were used stops from the 3rd hour till the 6th hour. In contrast, growth was observed from the 3rd hour till the 6th hour in a decreasing order when cefotaxime F was used. Our findings showed that some local brands of ciprofloxacin and cefotaxime have low efficacy when compared to the antibiotics procured from Oxoid Company, UK.