Prevalence and Antimicrobial Resistance Patterns of Gram-Negative Bacteria at Amhara Public Health Institute, Northwest Ethiopia: A Six-Year Retrospective Study

Background: The global rise of multidrug-resistant Gram-negative bacteria presents a major public health challenge, particularly in low- and middle-income countries. Limited antimicrobial resistance surveillance data in Ethiopia hampers evidence-based treatment and policy decisions.

Objective: This study assessed the prevalence and antimicrobial resistance patterns of Gram-negative bacteria isolated over six years (2018–2024) at the Amhara Public Health Institute (APHI), Northwest Ethiopia.

Methods: An institution-based retrospective study was conducted using archived microbiology laboratory data from January 2018 to December 2024. All culture-confirmed Gram-negative bacterial isolates with complete antimicrobial susceptibility test results were included. Antimicrobial susceptibility test was performed using the Kirby–Bauer disk diffusion method according to the CLSI guidelines. Data were analyzed SPSS version 26 software. Chi-square tests were used to assess the associations between outcome and demographic variables. Statistical significance was declared at p < 0.05.

Results: A total of 350 Gram-negative isolates were analyzed. Escherichia coli (29.4%, 95% CI: 24.6–34.2) and Klebsiella spp. (27.7%, 95% CI: 23.0–32.4) were the predominant isolates. Overall, 53.2% of isolates were classified as MDR. Highest resistance rates were observed against chloramphenicol (97.3%), sulfonamides (80.3%), and ampicillin (82.4%). The isolates showed the lowest resistance against Carbapenems (24.9%).  Age (χ² = 106.69, p < 0.001) and sex (χ² = 12.86, p = 0.045) were significantly associated with multidrug resistance bacterial infection.

Conclusion: More than half of Gram-negative isolates were multidrug resistant in the study area. Strengthening AMR surveillance, antimicrobial stewardship programs, and routine culture-based diagnosis is urgently required.