antibiotic susceptibility pattern of aerobic and anaerobic bacteria isolated from surgical site infection of hospitalized patients

materials and methods one hundred ssis specimens were obtained by needle aspiration from purulent material in depth of infected site. these specimens were cultured and incubated in both aerobic and anaerobic condition. for detection of antibiotic susceptibility pattern in aerobic and anaerobic bacteria, we used disk diffusion, agar dilution, and e-test methods. results a total of 194 bacterial strains were isolated from 100 samples of surgical sites. predominant aerobic and facultative anaerobic bacteria isolated from these specimens were the members of enterobacteriaceae family (66, 34.03%) followed by pseudomonas aeruginosa (26, 13.4%), staphylococcus aureus (24, 12.37%), acinetobacter spp. (18, 9.28%), enterococcus spp. (16, 8.24%), coagulase negative staphylococcus spp. (14, 7.22%) and nonhemolytic streptococci (2, 1.03%). bacteroides fragilis (26, 13.4%), and clostridium perfringens (2, 1.03%) were isolated as anaerobic bacteria. the most resistant bacteria among anaerobic isolates were b. fragilis. all gram-positive isolates were susceptible to vancomycin and linezolid while most of enterobacteriaceae showed sensitivity to imipenem. conclusions most ssis specimens were polymicrobial and predominant anaerobic isolate was b. fragilis. isolated aerobic and anaerobic strains showed high level of resistance to antibiotics. objectives this study aimed to investigate anaerobic and aerobic bacteria prevalence in surgical site infections and determinate antibiotic susceptibility pattern in these isolates. background surgical site infections (ssis) are infections of incision or deep tissue at operation sites. these infections prolong hospitalization, delay wound healing, and increase the overall cost and morbidity.