Bacterial etiologies, antimicrobial susceptibility patterns, and multidrug resistance trends among patients with sterile body site infections in Northwest Ethiopia

Sterile body site (SBS) bacterial infections are one of the most critical problems in hospital settings. The rise of antimicrobial resistance and empirical treatment of SBS infections without local up-to-date evidence have led to higher patient mortality, representing a research gap in the study area. Therefore, this study aimed to determine the bacterial distribution, their antimicrobial resistance patterns, multidrug resistance (MDR) trends, and associated factors in SBS infections at the University of Gondar Comprehensive Specialized and Referral Hospital, Northwest Ethiopia. A retrospective hospital-based cross-sectional study was conducted among patients with SBS infection at the University of Gondar Comprehensive Specialized and Referral Hospital. The Kobo data collection tool was used to extract laboratory records from September 2021 to May 2026 (five years) using a consecutive sampling technique. Sterile body fluid samples were collected and inoculated onto blood agar, chocolate agar, MacConkey agar, and mannitol salt agar plates. Antimicrobial susceptibility testing was performed using the modified Kirby-Bauer disc-diffusion method. Data were analyzed using SPSS version 26 software. Descriptive statistics, chi-square test assumptions, and logistic regression models were applied. Bivariate logistic regression results with a p-value < 0.25 were entered into multivariate analysis to control for potential confounding factors. To assess associations between dependent and independent variables, a p-value < 0.05 in multivariate analysis was considered statistically significant at the 95% confidence level. Study findings were presented using tables and charts. A total of 1,368 study participants were included in this study, consisting of 678 (49.6%) males and 690 (50.4%) females. The prevalence of culture-confirmed bacterial SBS infection was 5.48% (95% CI: 4.38%-6.83%), with 75 bacterial isolates identified. No mixed bacterial infections were detected in any patient. There was a high prevalence of Gram-negative bacteria (88.0%, n = 66), while 12.0% ( n = 9) were Gram-positive bacteria. E. coli (33.3%, n = 25) and K. pneumoniae (26.7%, n = 20) were the most predominant pathogens causing SBS infection. Gram-negative bacterial isolates demonstrated resistance to commonly used antibiotics such as ceftriaxone, trimethoprim-sulfamethoxazole, and ampicillin. An overall prevalence of MDR was 17.3% (13/75), with K . pneumoniae (35%, n = 6), Non-Lactose Fermenting Gram-Negative Rods (28.6%, n = 2), and E. coli (16%, n = 4). Being male ( p = 0.011) and study years 2025/26 ( p < 0.001), 2024/25 ( p < 0.001), and 2023/24 ( p = 0.020) were significantly associated with bacterial SBS infection. In this study, Gram-negative bacteria were the most common cause of SBS infection, with MDR E. coli and K. pneumoniae being frequently identified isolates. Over the five-year trend, a higher MDR rate was observed in 2024/25 (46.2%), with K. pneumoniae exhibiting a high MDR rate in 2024/25 (71.4%); p = 0.03, and the prevalence of MDR E. coli peaked at 50% during 2022/23 and 2024/25 tracking periods. This study highlights the need for continuous antimicrobial resistance surveillance and molecular detection of resistance mechanisms.