Prevalence and risk factors associated with infections linked to carbapenemase-producing Acinetobacter species circulating in the city of Yaoundé, Cameroon

Abstract

Objectives: Carbapenems are critical antibiotics used against multidrug-resistant infections, yet resistance is increasing, especially among Gram-negative bacteria like Acinetobacter species. In Cameroon, while Acinetobacter baumannii is well studied, little is known about other species such as Acinetobacter pittii, Acinetobacter nosocomialis, and Acinetobacter calcoaceticus. This study assessed the prevalence of carbapenemase-producing Acinetobacter and associated risk factors in Yaoundé hospitals.

Methods: A 6-month prospective cross-sectional study (April-September 2024) was conducted using 531 clinical samples from four health facilities. Strains were identified via morphologic, biochemical, and API 20 NE® tests. Antibiotic susceptibility was assessed using disc diffusion, and carbapenemases were characterized phenotypically.

Results: Of the samples, 4.9% yielded Acinetobacter, with A. baumannii being most common (80.8%), followed by A. calcoaceticus (11.5%) and Acinetobacter anitratus (7.7%). A. baumannii showed high antibiotic resistance, especially to beta-lactams, with 85.71% producing carbapenemases (83.33% class B and 16.67% class A). Significant risk factors included hospitalization, current antibiotic therapy, recent antibiotic use, and age group 38-47 years.

Conclusions: These findings highlight an urgent need for better surveillance, stricter antibiotic stewardship, and enhanced infection control strategies to limit the spread of resistant Acinetobacter infections in Yaoundé's health care settings.

Keywords: Acinetobacter; Carbapenemase; Health facilities; Prevalence; Risk factors; Yaoundé.

Figure 1

Prevalence of the Acinetobacter genus in the study population. This chart illustrates the proportion of samples containing Acinetobacter (4.9%) among the 531 clinical samples collected. Among these isolates, Acinetobacter baumannii (light blue) accounted for 80.8%, followed by Acinetobacter calcoaceticus (orange) at 11.5% and Acinetobacter anitratus (gray) at 7.7%. The remaining samples (dark orange, 95.1%) did not contain any Acinetobacter species.

Figure 2

Acinetobacter baumanii-producing carbapenemase. This bar chart shows the prevalence of carbapenemase types identified in Acinetobacter baumannii isolates. Class B enzymes (metallo-beta-lactamases) were the most common, detected in 83.33% of cases, whereas class A enzymes (serine-beta-lactamases) were found in 16.67%. Metallo-beta-lactamases hydrolyze beta-lactams through zinc-dependent mechanisms, whereas class A enzymes use serine at their active site.