Background: Operative Site Infections (SSIs) are infections of incision or deep tissue at operation sites. 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 users of family (66 34.03%) followed by (26 13.4%) (24 12.37%) (16 8.24%) coagulase negative (14 7.22%) and nonhemolytic streptococci (2 1.03%). (26 13.4%) and (2 1.03%) were isolated as anaerobic bacteria. The most resistant bacteria among anaerobic isolates were showed sensitivity to imipenem. Conclusions: Most SSIs specimens were polymicrobial JAG1 and predominant anaerobic isolate was Isolated aerobic and anaerobic strains showed high level of resistance to antibiotics. family are the predominant aerobe organisms that were reported in these infections (9). The development of selective media and precise laboratory protocols for the recovery and identification of anaerobic bacteria have greatly enhanced our knowledge of their clinical importance. Most common anaerobe organisms that were reported from SSIs are spp. (10 11 In one microbiology study accomplished by Munez et al. (8%) (15%) (8%) (7%) (7%) (3.6%) and (9%) were isolated from SSIs (12). In another study by Saini et al. the isolated bacteria from these infections were and (37.5%) and spp. (32.5%) as the predominant bacteria from postoperative infections in different medical procedures wards (13). 2 Objectives Owning to low antibiotic susceptibility in aerobic and anaerobic bacteria and presence of these bacteria in SSIs both empirical therapy and antimicrobial prophylaxis administration may not be appropriate for these infections. Therefore microbiology laboratory has a vital role in identification and determination of antibiotic susceptibility pattern in these infections. So the aim of this study was to investigate anaerobic and aerobic bacteria profile in surgical site infections and determination of antibiotic susceptibility pattern in these isolates. 3 Materials and Methods 3.1 Hospital Establishing Imam Reza hospital with 520 beds in 26 clinical wards including nephrology gastroenterology pulmonology endocrine and rheumatology neurology infectious disease ICU of neurology ICU of neurology medical procedures ICU of general medical procedures and of pulmonary can be found in Tabriz Town. This hospital provides services for 2000 BIRB-796 patients on a monthly basis nearly. Medical center environment cleaning practice is conducted by particular group regulatory with drinking water disinfectant and detergent. The most frequent way of personnel hand hygiene is normally hand cleaning with cleaning soap and drinking water and big squirt usually are requested tables washing. 3.2 Assortment of Specimens Between Oct 2012 and July 2013 100 SSIs specimens (sort of infections and anatomic location weren’t considered in sampling) extracted from preferred sufferers hospitalized in Imam Reza Medical center. A number of the sufferers were going through treatment with antibiotic medications such as for example metronidazole vancomycin clindamycin imipenem ceftriaxone and various other cephalosporins. All gathered specimens were prepared for the recognition of anaerobe and aerobe bacterias in medical microbiology lab of medication faculty. For sampling contaminated site was initially scrubbed with povidone-iodine and lifestyle specimens were attained by BIRB-796 comprehensive needle aspiration of materials in the infected site (9). First of all a drop of aspiration was launched to thioglycolate broth medium and then BIRB-796 syringe was immediately sealed (9 14 Specimens were transported to laboratory within 20 moments and generally inoculated within 1 hour after collection. 3.3 Microbial Investigation A Gram-stain smear was used for cytology investigation and detection of bacterial presence in specimens. For the isolation of aerobic organisms specimens were plated onto chocolates sheep blood (5%) (Liofilchem) phenylethyl alcohol (PEA) (Hi there Meia India) and MacConkey agar (Lio-filchem Italy) plate. The plates were incubated at 37°C under 10% CO2 and examined at 24 hours and 48 hours later on. Pre-reduced vitamin K enriched brucella blood agar; kanamycin-vancomycin laked blood agar (KVLB Basal Medium is definitely Brucella agar; Fluka Chmie AG CH-9471 Buchs Switzerland) bacteroides bile esculin (BBE Himedia Laboratories Pvt. Ltd India) and phenylethyl alcohol (PEA) agar were inoculated for isolation of anaerobic organisms. The plate press were incubated under 80% N2 10 CO2 10 H2 and 0% O2 in anaerobic jar by using BIRB-796 Anoxomat (MART microbiology B.V. The Netherlands) and these plates examined at 48 72 and 96 hours. The primary inoculated thioglycolate broth (Merck Co..