Epidemiology and antimicrobial resistance patterns of bloodstream infection pathogens in northern Iran

Résumé fourni par la source

Bloodstream infection (BSIs) is life-threatening conditions associated with increasing antimicrobial resistance (AMR), particularly in low- and middle-income countries. Local surveillance data are essential to guide empirical therapy and antimicrobial stewardship. This study aimed to determine the microbial etiology and antimicrobial resistance patterns of BSIs in two tertiary hospitals in northern Iran over a three-year period. A three-year retrospective study was conducted on 792 non-repetitive positive blood cultures collected from March 2021 to March 2024 at Bou-Ali Sina Hospital and Razi Infectious Disease Center. Bacterial identification and antimicrobial susceptibility testing were performed using standard microbiological techniques and the Kirby–Bauer disk diffusion method. A total of 792 positive blood culture isolates were analyzed. Among the isolates, 433 (54.6%) were Gram-positive bacteria, 357 (45.1%) were Gram-negative bacteria, and two (0.3%) were Candida spp. Among Gram-negative bacteria, Pseudomonas aeruginosa was the most prevalent isolate ( n = 88, 11.1%), whereas Acinetobacter spp. accounted for a substantially smaller proportion ( n = 18, 2.2%). Among Gram-positive isolates, Staphylococcus epidermidis ( n = 297) exhibited the highest resistance to ampicillin (53.1%) and the lowest to tetracycline (9.2%). No vancomycin-resistant Staphylococcus spp. or Enterococcus spp. were identified. Our results emphasize the need for clinicians to have access to up-to-date bacterial susceptibility data for routinely prescribed drugs. In northern Iran, device-associated BSIs caused by resistant staphylococci and MDR Gram-negative bacilli predominate. Third-generation cephalosporins are no longer suitable for empirical monotherapy at least in our region. Amikacin and vancomycin demonstrated the most favorable in vitro activity against the predominant Gram-negative and Gram-positive pathogens.