Phenotypic Detection of Extended Spectrum β-Lactamase and AmpC producing Enterobacteriaceae Isolated in A General Hospital

Abstract

Objective: The antibiotic resistance of Enterobacteriaceae is a worldwide preoccupation, and misuse antibiotics of beta-lactam group allowed the development of bacteria producing extended spectrum beta-lactamase and cephalosporinase AmpC enzymes type resistance. The aim of this study was to determine the frequency of these enzymes among strains isolated at the General Hospital in Douala, Cameroon. Methods: We conducted a cross-sectional study. For phenotypic detection of resistance enzymes, MASTDISCS™ test impregnated third and fourth generation cephalosporin’s was used by diffusion on Mueller Hinton agar. Measuring the inhibition areas and comparing the inhibition diameters determined the nature of the resistance mechanism. Results: This study included 195 strains of Enterobacteriaceae. The most frequent species were Escherichia coli and Klebsiella pneumoniae, with a frequency of 49.2% and 31.3% respectively. After determination of resistance phenotypes, 101 (51.8%) isolates were found to be producing resistance enzymes. The frequency of ESBL-producing Enterobacteriaceae was 19.5%; AmpC producing was 14.3% and both enzymes (AmpC + ESBL) 17.9%. E. coli and K. pneumoniae resistance rates were 90% and 83.7% for Cotrimoxazole, 82.5% and 78.3% for ciprofloxacin, 20% and 13.5% for Amikacin, respectively. Imipenem, Amikacin and Fosfomycin were the most active molecules with 4.9%, 19.8% and 33.6%, out of 101 resistant strains, respectively. Conclusion: This study showed a high frequency of resistance enzyme producing strains. This situation leads to resistance to antibiotics most commonly used. This finding justifies a change in prescription habits for protection of molecules that are still active. J Microbiol Infect Dis 2018; 8(3):113-119