Bloodstream infections (BSIs) are life-threatening conditions that increase morbidity, lengthen hospital stays, and raise mortality. Bacterial pathogens are most commonly isolated worldwide, and in low- and middle-income countries the ESKAPEE group (Enterococcus spp., Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp. and Escherichia coli) frequently predominates. Antimicrobial resistance (AMR) among BSI pathogens is a growing global threat and is especially consequential in resource-limited settings where empiric therapy is common and laboratory surveillance is limited. This study aimed to describe the bacterial profile and antimicrobial resistance patterns among patients with suspected BSIs referred to the Amhara Public Health Institute (APHI) bacteriology reference laboratory.
Study design and setting
This was a four-year retrospective review of laboratory blood culture and antimicrobial susceptibility records from APHI covering January 1, 2020 to December 30, 2023. APHI is an accredited reference laboratory serving a population of over 28.54 million in north-western and north-central Ethiopia.
Data sources and inclusion criteria
Records were retrieved on January 6, 2025, using a standardized data collection form. Extracted variables included patient sex, age, culture growth status, identified species, and antimicrobial susceptibility results. Patients were stratified for analysis into neonates (≤ 28 days), pediatrics (>28 days to 14 years), and adults (≥ 15 years). Records with missing or illegible data and those identified as contaminants were excluded.
Laboratory methods
Blood sampling and culture followed standardized manual blood culture procedures aligned with World Health Organization recommendations. Isolates were identified and antimicrobial susceptibility testing performed by the Kirby–Bauer disk diffusion method with interpretation according to Clinical and Laboratory Standards Institute (CLSI) guidelines. The study reports susceptibility and resistance frequencies as recorded in the laboratory dataset.
Statistical analysis
Descriptive statistics and regression models were applied using SPSS version 20. Statistical significance was defined as p < 0.05. Adjusted odds ratios were used to identify independent predictors of culture positivity.
Culture positivity and organism distribution
Of 676 blood culture records screened, true bacterial pathogens were isolated from 50.3% (340/676). Gram-negative bacteria represented 61.2% (208/340) of isolates, while Gram-positive bacteria accounted for 38.8% (132/340). The ESKAPEE group constituted 96.5% (328/340) of all isolates. The most frequent species were Klebsiella spp. (25.9%, 88/340), Enterococcus spp. (20.9%, 71/340), and Staphylococcus aureus (15.6%, 53/340).
Antimicrobial resistance patterns
Among Gram-positive isolates, reported high resistance rates included oxacillin 74.5% (41/55 tested), penicillin 72% (36/50 tested), and vancomycin 51.1% (24/47 tested) where susceptibility results were available. Gram-negative isolates showed critically elevated resistance to commonly used agents: ampicillin 100% (24/24), ceftriaxone 92.4% (157/170), and trimethoprim–sulfamethoxazole 89.4% (126/141) among tested isolates.
Multidrug resistance classifications
Overall resistance phenotypes in the dataset included multidrug-resistant (MDR) organisms in 43.8% (149/340) of isolates, extensively drug-resistant (XDR) in 30.5% (104/340), and pandrug-resistant (PDR) in 5.3% (18/340). These resistance profiles showed similar distributions among ESKAPEE strains.
Predictors of culture positivity
In adjusted analyses, sex and age were independent predictors of culture positivity. Female sex was associated with 44% lower odds of a positive blood culture (p = 0.002). Compared with elderly patients, neonates (≤ 28 days) had 4.7-fold higher odds of culture positivity (p = 0.001), and young adults aged 15–24 years had 9.5-fold higher odds (p = 0.001).
This APHI laboratory surveillance dataset demonstrates a high BSI positivity rate (50.3%) with predominance of Gram-negative and ESKAPEE pathogens. Reported resistance was substantial across both Gram-positive and Gram-negative organisms, including high rates to frontline and nationally recommended antimicrobials such as ceftriaxone and ampicillin. The large proportions of MDR, XDR and PDR isolates indicate limited therapeutic options and underscore the urgency of antimicrobial stewardship and updated empiric therapy guidelines in this setting.
The observed demographic associations—higher odds of culture positivity among males, neonates, and young adults—highlight subgroups that may warrant targeted prevention and diagnostic attention. The study followed WHO-recommended manual culture procedures and CLSI-guided disk diffusion testing; however, the authors note the need for expanded laboratory capabilities (for example, anaerobic culture, minimum inhibitory concentration testing, and molecular sequencing) to improve detection and resistance tracking.
This retrospective analysis reveals a severe burden of bloodstream infections at APHI driven largely by highly resistant ESKAPEE and Gram-negative pathogens. The authors recommend immediate implementation and strengthening of antibiotic stewardship programs, revision of empirical treatment guidelines based on up-to-date local data, and enhancement of laboratory capacity to include anaerobic culture, MIC determination, and molecular methods for resistance surveillance. Such measures are required to monitor and manage the high AMR levels identified.
Note: All numeric results and procedural descriptions above are extracted directly from the referenced APHI laboratory dataset and the published article; additional methodological or site-specific operational details beyond those reported were not provided in the source.