Phenotypic Characterization of Enterobacteriaceae and Pseudomonas aeruginosa Isolates Producing Extended-spectrum Beta-lactamase and carbapenemase recovered across five hospitals in Yaoundé, Cameroon

Abstract

Enterobacteriaceae and Pseudomonas aeruginosa are implicated in severe nosocomial and healthcare-acquired infections. The emergence of strains producing Extended-spectrum β- lactamases (ESBL) and carbapenemases reduces the efficacy of lastline antibiotics, making these infections more difficult to treat. The aim of this study was to characterize phenotypically Enterobacteriaceae and Pseudomonas aeruginosa isolates producing Extended-spectrum β- lactamases and carbapenemases recovered across five hospitals in Yaoundé. A cross-sectional study was conducted from November 2023 to August 2024. Isolates obtained from various clinical samples were identified using API 20 E and API 20NE Galleries. Antibiotic susceptibility testing was performed according to CASFM/ EUCAST recommendations. Extended-spectrum β- lactamases and carbapenemases production were evidenced by the double disc synergy tests. A total of 280 isolates of Enterobacteriaceae were isolated from stool samples, with Escherichia coli being the frequently isolated specie 74.29 % (208/280). A high rate of resistance was observed in Klebsiella pneumoniae, with 100 % resistance to Ceftazidime and 90 % to Cefotaxime. Similarly, resistance to Carbapenems revealed high rates of resistance in Escherichia coli (59.13 % resistance to Imipenem and 33.17 % to Meropenem). Of the 280 enterobacterial isolates, 20.35 % (57/280) were ESBL producers, while 10.71% produced carbapenemases, and 3.57 % of (10/280) showed co-expression of ESBL and carbapenemases. Pseudomonas aeruginosa isolates showed a high rate of resistance to β-lactam antibiotics, particularly Ceftazidime (79.09 %) and Ticarcillin (69.09%). ESBL production was observed in 13.63 % (15/110) and carbapenemase production in 19.09% (21/110), while co-production of ESBL and carbapenemase was detected in 7.27% (8/110). This study evidences an increased risk of resistance to the most widely available antibiotics in healthcare settings. It remains important to set up therapeutic and resistance monitoring committees.

Keywords: Enterobacteriaceae, Pseudomonas aeruginosa, Extended-spectrum β-lactamases, Carbapenemases.