Quinolones resistance and R-plasmids of some gram negative enteric bacilli

OA Daini, OD Ogbolu, A Ogunledun



Out of the two hundred and sixty bacteria isolates from clinical specimens obtained from different body sites at the University College Hospital Ibadan, 166 belonged to the family of Enterobacteriaceae and Pseudomonaceae. The isolated gram-negative enteric bacilli consist of Escherichia coli (22), Klebsiella species (65), Proteus species (20), Salmonella typhi (2), Pseudomonas aeruginosa (39) and Pseudomonas species (18). Among the antimicrobial agents tested, high resistance was found with ofloxacin 44.0%, followed by pefloxacin 30.1% and ciprofloxacin 21.7%. Ciprofloxacin has the lowest MIC of 2 – 32 μg/ml while ofloxacin has the highest 64 μg/ml. Of the 166 strains, 44 were resistant to most of the antimicrobial agents tested. All the strains that were resistant to any antimicrobial agents were also resistant to ofloxacin. A total of 27 plasmids ranging in molecular sizes from 6.6.kb to 17.4kb were extracted from the resistant strains and grouped into 5 plasmid profiles. Transformation experiment revealed that 59.2% of the resistant strains carried a common R-plasmid of size 10.7kb. Plasmid-mediated resistance to ciprofloxacin and pefloxacin was found. Klebsiella species harboured the highest number of R-plasmids with 8, followed by Pseudomonas aeruginosa with 4.

Afr. J. Clin. Exper. Microbiol. Vol.6(1) 2005: 14-20