Activity of beta-lactam antibiotics and production of beta-lactamases in bacteria isolated from wound infections in Brazzaville, Congo

Abstract

To determine the mechanism of bacterial beta-lactam resistance, 165 bacteria isolated from wounds of hospitalized patients composing of: 42 Staphylococcus aureus, 37 Pseudomonas aeruginosa, 23 Escherichia coli, 22 Proteus, 12 Klebsiella, 10 coagulase-negative staphylococci (CNS), eight Enterobacter, six Citrobacter, five Providencia were tested for their sensitivity to beta-lactams and their production of beta-lactamases. The antibiotic susceptibility was considered by the method of the standard diffusion on agar Mueller Hinton. The rate of production of beta -lactamase in all bacteria was determined using the Strips of nitrocefin. The percentages of resistance to beta-lactams obtained were as follows: Staphylococcus aureus (77.90%), Pseudomonas aeruginosa (44.14%), E. coli (73.8%), Proteus (57.4%), Klebsiella (63.6%), CNS (57.15%), Enterobacter (56.3%), Citrobacter (83.3%), Providencia (67.5%). The rate of beta-lactamases were as follows: S. aureus (7.34%), P. aeruginosa (89.19%), E. coli (95.65%), Proteus (86.36%), Klebsiella (91.67%), CNS (90%), Enterobacter (87.5%), Citrobacter (66.67), Providencia (100%). The studied bacteria produce beta-lactamases which is the primary mechanism of resistance to beta-lactam antibiotics in the majority of the bacteria. Beta-lactamases rates vary from one genus to another. It is extended spectrum beta-lactamase-producing strain.