Phenotypic Characterization and Prevalence of Carbapenemase-Producing Pseudomonas aeruginosa Isolates in Six Health Facilities in Cameroon

Abstract

Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen with a great ability to adapt to stress, in particular, to the selective pressure of antibiotics in the hospital environment. This pathogen constitutes a real public health concern, especially in low- and middle-income countries. In Cameroon, little is known about the drug resistance patterns of Pseudomonas aeruginosa. This study sought to determine the prevalence of Pseudomonas aeruginosa strains producing carbapenemases in six health facilities in the center, littoral, and west regions of Cameroon. An analytical cross-sectional study was conducted over a four-month period from July to October 2021. All Pseudomonas aeruginosa or suspected strains isolated from pathological products at the bacteriology laboratory of different health facilities were systematically collected and underwent a re-identification. After growing on cetrimide agar and successfully subculturing on nutrient agar, an oxidase test was performed on pure colonies, followed by biochemical identification (API 20NE system) of the bacterial suspension (0.5McFarland standard). Drug susceptibility testing for the detection of extended-spectrum beta-lactamases of overproduced inducible cephalosporinases and carbapenemases was performed according to adequate standard procedures. Of the 468 isolates collected, 347 (74.14%) were confirmed Pseudomonas aeruginosa after re-identification, of which 34.49% (120/347) produced inducible cephalosporinases (CAZR and C/TS) and 32.26% (112/347) extended-spectrum beta-lactamases. The prevalence of carbapenemase-producing P. aeruginosa (IMPR and C/TR) was 25.07% (87/347), with 17.24% (15/87) class A and 82.76% (72/87) class B. A high rate of resistance to penicillin (piperacillin: 70.58% and ticarcillin: 60.24%) was observed. We also noted a 34.49% resistance to ceftazidime, 30.22% to imipenem against 37.02% to meropenem, and 25.1% to ceftolozane/tazobactam (C/T). These strains also exhibited 79.57% resistance to quinolones and about 26% to aminoglycoside families. Multivariate analysis revealed that carbapenemase-producing Pseudomonas aeruginosa-related infections were significantly associated with hospitalization (p = 0.04), maternity (p = 0.03), surgery (p = 0.04), and intensive care wards (p = 0.04). This study highlighted a high burden of resistant strains of carbapenemase-producing Pseudomonas aeruginosa. Surveillance should be intensified to prevent the dissemination and spread of these strains.