Bacterial profile of surgical site infection and antimicrobial resistance patterns in Ethiopia: a multicentre prospective cross-sectional study
Authors: Worku Seble , Abebe Tamrat , Alemu Ashenafi , Seyoum Berhanu , Swedberg Göte , Abdissa Alemseged , Mihret Adane , Beyene Getachew Tesfaye 
Published: November 2023

Abstract
Background
Globally, surgical site infections (SSI) are the most commonly reported healthcare-associated infections.

Methods
A multicentre study was conducted among patients who underwent surgical procedures at four hospitals located in Northern (Debre Tabor), Southern (Hawassa), Southwest (Jimma), and Central (Tikur Anbessa) parts of Ethiopia. A total of 752 patients clinically studied for surgical site infection were enrolled. The number of patients from Debre Tabor, Hawassa, Jimma, and Tikur Anbessa, hospitals was 172, 184, 193, and 203, respectively. At each study site, SSI discharge culture was performed from all patients, and positive cultures were characterized by colony characteristics, Gram stain, and conventional biochemical tests. Each bacterial species was confirmed using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI TOF). An antimicrobial susceptibility test (AST) was done on Mueller–Hinton agar using the disk diffusion method. Logistic regression analysis was used to assess associations of dependent and independent variables. A p-value < 0.05 was considered statistically significant. Data were analysed using STATA 16 software.

Results
Among 752 wound discharge cultures performed, 65.5% yielded growth. Among these, 57.9% and 42.1% were Gram-negative and Gram-positive isolates, respectively. In this study, a total of 494 bacteria were isolated; Staphylococcus aureus (31%), Escherichia coli (20.7%), and Klebsiella pneumoniae (9.8%) were the most common. Rare isolates (0.8% each) included Raoultella ornithinolytica, Stenotrophomonas maltophilia, Alcalignes faecalis, Pantoea ecurina, Bacillus flexus, and Paenibacillus tylopili. Enterobacteriaceae showed high levels of resistance to most of the tested antibiotics but lower levels of ertapenem (32.9%), amikacin (24.3%), imipenem (20.3%), and meropenem (17.6%) resistance. Multidrug-resistant (MDR) frequency of Enterobacteriaceae at Debre Tabor, Hawassa, Jimma, and Tikur Anbessa hospitals was 84.5%, 96.5%, 97.3%, and 94%, respectively. Ages ≥ 61 years (AOR = 2.83, 95% CI: 1.02–7.99; P 0.046), prolonged duration of hospital stay (AOR = 4.15, 95% CI: 2.87–6.01; P 0.000), history of previous antibiotics use (AOR = 2.83, 95% CI: 1.06–2.80; P 0.028), history of smoking (AOR = 2.35, 95% CI: 1.44–3.83; P 0.001), emergency surgery (AOR = 2.65, 95% CI: 1.92–3.66; P 0.000), and duration of operation (AOR = 0.27, 95% CI: 0.181–0.392; P 0.000) were significant risk factors.

Conclusion
The most prevalent isolates from Gram-positive and Gram-negative bacteria across all hospitals were S. aureus and E. coli, respectively. Many newly emerging Gram-negative and Gram-positive bacteria were identified. Variation between hospitals was found for both SSI etiology type and MDR frequencies. Hence, to prevent the emergence and spread of MDR bacteria, standard bacteriological tests and their AST are indispensable for effective antimicrobial stewardship.