Emerging antibiotic resistance in Vibrio cholerae: a study of cholera prevalence and resistance patterns in Zambia's Copperbelt Province.

Abstract

Introduction: Cholera remains a significant public health challenge in Zambia, particularly in the Copperbelt Province, where antibiotic-resistant Vibrio cholerae strains are increasingly threatening treatment efficacy. This study aimed to determine the prevalence of cholera and the antibiotic resistance patterns of V. cholerae isolates at three tertiary hospitals in the region.

Methods: A retrospective cross-sectional study was conducted across three major referral hospitals in the Copperbelt Province (Arthur Davison Children's Hospital, Kitwe Teaching Hospital, and Ndola Teaching Hospital) during the cholera outbreak from January to April 2024. Clinical samples from suspected cholera cases were analysed, and antimicrobial susceptibility testing was performed following Clinical Laboratory Standards Institute guidelines and the European committee on antimicrobial susceptibility testing methodology for Vibrio cholerae. To isolate Vibrio cholerae, alkaline peptone water and thiosulfate-citrate-bile salt-sucrose agar were utilized. The isolates were identified based on colony morphology, Gram staining, biochemical testing, and serotyping. Antimicrobial susceptibility testing was conducted by using the Kirby-Bauer disk diffusion method. Descriptive statistics were employed to assess the prevalence of Vibrio cholerae, and chi-square tests were applied with p-values of < 0.05 indicating statistical significance.

Results: Of the 892 suspected cases, 334 (37.4%) were confirmed as V. cholerae through culture. The highest number of V. cholerae confirmed cases was recorded at Ndola Teaching Hospital 221 (24.8%), followed by Kitwe Teaching Hospital 88 (9.9%), while Arthur Davison Children's Hospital 25 (2.8%) reported the lowest. High antimicrobial resistance was observed trimethoprim/sulfamethoxazole 69 (74.2%), ampicillin 75 (54.3%), and imipenem 22 (46.8%). In contrast, erythromycin 25 (100%), gentamicin 6 (85.7%) and ciprofloxacin 118 (76.6%) remained highly effective. The overall prevalence of multidrug resistance (MDR) in Vibrio cholerae was 3.7%. Among these, resistance to four or more antibiotics was observed in 3 (1.2%), followed by resistance to the combination of Ciprofloxacin, Ceftazidime, and Tetracycline in 2 (0.8%). All other MDR patterns were detected in a single isolate each (0.4%).

Conclusion: The high prevalence of antibiotic-resistant Vibrio cholerae in the Copperbelt Province underscores the urgent need for enhanced antimicrobial stewardship and robust surveillance systems to inform effective cholera control strategies. Sustainable public health impact can be achieved through targeted immunization campaigns in endemic areas combined with strengthened water, sanitation, and hygiene (WASH) interventions, including improved access to clean water, adequate sanitation infrastructure, hygiene promotion, and supportive policies, which are essential for reducing transmission and preventing future outbreaks in vulnerable populations. However, because the number of antibiotics used in antimicrobial susceptibility testing across isolates varies, these results should be interpreted cautiously. Such differences may affect the comparability and overall interpretation of resistance patterns.