Phenotypic Detection of Extended Spectrum Beta-Lactamase and Carbapenemases Produced by Klebsiella spp Isolated from Three Referrals Hospitals in Yaounde, Cameroon

Aims: The main objective of this study was to determine the resistance phenotype of β-lactamines by Klebsiella in three hospitals in Yaoundé.
Study Design: A cross-sectional descriptive study.
Place and Duration of Study: Bacteriology laboratories of three referrals hospitals in Yaounde (University Teaching Hospital, General Hospital and Gynaeco-Obstetric and Pediatric Hospital) between May and November 2013.
Methodology: A cross-sectional descriptive study was carried out over a 6 month-period from May to November 2013 in the bacteriology laboratories of three referrals hospitals in Yaounde. 99 strains ofKlebsiella spp. were collected for the study. Antimicrobial susceptibility testing was done using the disc diffusion method. The antibiotics tested were the β-lactams, other inhibitors like clavulanic acid, tazobactam, Ethylene-Diamine-Tetra-Acetic Acid (EDTA), cloxacillin and 3-aminophenyl boronic acid hydrochloride. The minimum inhibitory concentration (MIC) was also determined to enable the classification of the different resistance phenotypes.
Results: Ninety-nine Klebsiella spp. were identified from urine (52.5%), blood (21.2%), pus (15.2%) and others sites (11.1%). The distribution of the Klebsiella spp. was: Klebsiella pneumoniae pneumoniae (78.7%), Klebsiella oxytoca (12.12%), Klebsiella pneumoniae ozaenae (5.05%), and Klebsiella pneumoniae rhinoscleromatis (4.04%). The isolates were most resistant to piperacillin (76%) and cephalothin, (85%). The most active antibiotics were imipenem (99%), and ertapenem (77%). The phenotypic tests revealed the following resistance phenotypes: extended-spectrum beta-lactamase (30.30%), wild (27.27%), penicillinase resistant to inhibitors (16.16%), carbapenemase (11.11%). Out of these 99 Klebsiella spp., 5 were carbapenemases producers of class C and 6 of class D. The MIC were variable with different antibiotics tested but the MIC of imipenem were always lower than 1 µg/ml.
Conclusion: The interpretation of the antimicrobial susceptibility testing has enabled the establishment of a high prevalence of expanded spectrum β-lactamase and consequently leading to an increase in the presence of carbapenemase producing Klebsiella spp. This could lead to therapeutic failure in case of treatment with beta-lactamines antibiotics. Therefore this trend needs to be monitored.