Identification of Pathogenic Bacteria in Blood Cultures and Susceptibility Testing of Isolates With Various Antibiotics

Background: Blood infections are an extensive range of disorders that can vary from limited bacteremia to fatal septicemia. Bacteremia refers to the transient presence of a bacterium in the bloodstream. A delay in the diagnosis and treatment of sepsis can cause mortality, with a ۲۰% - ۵۰% prevalence rate. Objectives: Due to the changing patterns of antibiotic resistance, as well as differences in patterns over time in different settings, we decided to identify infectious agents and their antibiotic resistance patterns in blood cultures. Materials and Methods: This study was conducted at Shahid Beheshti hospital, Hamadan, Iran, during a one-year period (March ۲۱, ۲۰۱۴, to March ۲۲, ۲۰۱۵). From patients with suspected bloodstream infections, ۵-۱۰ mL of blood was collected three times and inoculated into culture bottles. After identifying the types of microorganisms, susceptibility testing was performed according to CLSI standards, and the results were analyzed with statistical software. Results: In the present study, ۲,۱۳۰ blood cultures were obtained from ۷۱۰ patients (۳۸۴ females and ۳۲۶ males). Of these cultures, ۲۳۲ (۱۸.۹%) were positive; ۱۰۷ (۴۶%) and ۱۲۵ (۵۴%) were from females and males, respectively. Most of the positive cultures were related to the internalmedicine and hematology wards, which had ۱۳۲ cases (۵۶.۹%), and the ICU, with ۳۷ cases (۱۶%). Themost frequent isolates were Pseudomonas aeruginosa, Escherichia coli, Acinetobacter baumannii, and coagulase-negative Staphylococcus aureus, with prevalence rates of ۱۸.۲%, ۲۴.۱%, ۱۰.۳%, and ۱۰.۳%, respectively. The most effective antibiotic against Gram-positive isolates was vancomycin. Conclusions: This study revealed that the most effective antibiotics against two Gram-negative and Gram-positive groups were amikacin and norfloxacin, so it is recommended that these antibiotics be used empirically, at least in the setting where this study was conducted, before performing the culturing and antibiogram process.