Abstract:
The increase of β-lactamases producing-Pseudomonas aeruginosa has led to major therapeutic failures and continues to pose a significant clinical challenge in healthcare settings. This study aimed determining the molecular characterization of β-lactams resistance in P. aeruginosa isolates obtained from clinical sources at The Nairobi Hospital in Kenya. A Laboratory based cross-sectional descriptive design was used with the laboratory analysis of the samples being carried out in the Microbiology Section of the Department of Pathology. Phenotypic characterization of Extended Spectrum β-Lactamases (ESBL) and Metallo-β-Lactamases (MBL)-producing isolates was done using Vitek 2 System and antimicrobial susceptibility profiles. Genotypic characterization was done using Polymerase Chain Reaction assays and gel electrophoresis. Patients’ demographic data were collected from laboratory request forms. Data analysis was done using SPSS version 21.0 and Chi-square test. The high rate of P. aeruginosa isolates was found in indoor patients (74.1 %) than outdoor patients (25.9 %) with a high prevalence of this bacterium in males (61.1 %) than females (38.9 %). The predominance of this organism was also observed in the older age groups (64.3 %) comprising the patients above 45 years old. Phenotypical investigation of ESBL enzymes did not reveal a positive result. Overall the prevalence of MBL producers (22.7 %) was of serious concern as compared to non-MBL isolates (77.3 %); since all MBL isolates were resistant to the antibiotics tested. There was a significant association (p<0.001) in terms of antibiotic resistance, between MBL and non-MBL producing isolates for gentamycin, amikacin, ciprofloxacin, piperacillin/tazobactam, cefepime, ceftazidime, meropenem, and aztreonam. The highest rate of MBL producers was obtained from Intensive Care Unit (45.2 %) and High Dependency Unit (28.6 %) with higher distribution in pus swab (38.1 %); and sputum (33.3 %). There were two predominant genes blaVIM-2 (28.57 %) and blaNDM-1 (66.67 %) among MBL isolates. The rate of MBL producing isolates reported in this hospital suggests the existence of resistance emergence among the population of nosocomial bacteria. The early detection of β-lactamases producing isolates and the correct use of β-lactam antibiotics including carbapenems may help in the treatment of pseudomonal infections and avoid further spread of these multidrug resistant P. aeruginosa.
