Background: Surgical Site Infections (SSIs) or post-operative wound infections constitute as one of the frequently encountered nosocomial infections worldwide. The impact of SSIs implies substantial morbidity and mortality rates, length of hospital stay and economic cost. Objectives: To determine the spectrum of bacteria isolated from surgical site wound infections and their antibiotic susceptibility patterns in patients at Sri Jayewardenepura General Hospital, Sri Lanka. Methodology: This study was conducted at Sri Jayewardenepura General Hospital, Thalapathpitiya, and Sri Lanka. From 80 reported incidences of SSIs in the 2016, 57 cases were collected. The study was conducted for a period of 4 months from June to October of 2017, using a retrospective cohort study design. Data capture sheets were used to extract demographic characteristics, clinical history and operative information from patients’ records. Antimicrobial susceptibility pattern of bacterial pathogens isolated from surgical site wound infections was analysed by WHONET software version 5.6.Results: Coliform spp. (42.86%) were the most common isolated pathogen from surgical site wound infections followed by Staphylococcus aureus (21.4%) and Pseudomonas spp. (14.3%). Among 21.43% of staphylococcus aureus isolated from surgical site wound infections 14.29% reported as MRSA (Methicillin Resistance Staphylococcus aureus). Cefuroxime was the most commonly used preoperative surgical antimicrobial prophylaxis. Gram negative enteric isolates were highly sensitive to imipenem, levofloxacin, netilmicin and meropenem while 100% resistance showed to ceftazidime. Most of the gram negative isolates showed multiple resistance to commonly prescribed surgical antibiotics. Antimicrobial profile of Staphylococcus aureus revealed maximum sensitivity to teicoplanin, vancomycin, chloramphenicol and rifampicin while totally resistance to oxacillin.Conclusion and Recommendation: Coliform spp. were the most commonly isolated pathogen. Most of the gram negative isolates showed multiple resistance to commonly used antimicrobial agents. Cefuroxime was the most commonly prescribed surgical antimicrobial prophylaxis. It is highly recommended to use the ESBL confirmatory test to confirm ESBL positivity of coliforms. From the results obtained, it is suggested to closely monitor the patients who are having diabetes mellitus, hypertension and dyslipidaemia before and after the surgery. Care should be given to the patients over 60 years of age. Hospital antibiogram is a necessity to determine the empirical treatment for the better patient care and results of the study revealed the importance of adhering to strict guidelines for antibiotics prescriptions for proper treatment of SSIs.In Accordance to our knowledge, up to now, this is the first documented study regarding SSIs, patients’ characteristics associated with SSIs and antimicrobial susceptibility pattern of different bacteria causing SSIs in Sri Lanka. The current study identified 0.96% of SSI incidence rate for the year 2016. Most of the patients readmitted to the hospital after surgery, complaining non-specific symptoms. Females were mostly affected by SSIs while patients > 60 years of age suffered from SSIs within the year 2016. Patients having SSIs reported a history of previous hospitalization within 6 months. Majority of patients had any disease with or without dyslipidemia by the time of re-admission (36.84%). Moreover considerable number of patients were reported with diabetes mellitus and hypertension (17.54%). We observed a predominance of gram negative bacteria from SSIs, coliform spp. being the commonest isolate followed by pseudomonas spp. Cefuroxime was the commonly prescribed antimicrobial prophylaxis during the study period. We found that most of the gram negative isolates were multiple resistant to commonly prescribed antimicrobial agents during the year 2016. Empirical treatment for Acinetobacter spp. is netilmicin whereas empirical treatments for Pseudomonas spp. are amikacin, gentamicin, meropenem, ciprofloxacin and piperacillin/tazobactum. Suggestive empirical treatments for Staphylococcus spp. including S.aureus and MRSA are teicoplanin, vancomycin, chloramphenicol and rifampicin. Empirical treatments for coagulase negative Staphylococcus spp. are teicoplanin, chloramphenicol and vancomycin. Present study found an increased isolation rate of Extended Spectrum Beta Lactamases producing coliforms and methicillin resistant Staphylococcus aureus causing SSIs in the year 2016. Limitations of the study • Anaerobic bacterial profile and fungal cultures were not included. Further studies can be undertaken in this regard. • Species level identification had not been performed except for Staphylococcus aureus & ?-hemolytic Streptococci • Patients who have got treatments from general practitioners other than Sri Jayewardenepura General Hospital were not calculated under incidence of surgical site wound infections.RecommendationsFrom this study findings it is recommended to;a) Use antimicrobial sensitivity including ESBL screening and MRSA test results to guide choice of antibiotics.b) Use ESBL confirmatory test to confirm ESBL positivity.c) Consider the antibiogram obtained for different gram positive & negative bacterial isolates to understand the empirical treatment for gram positive & negative bacterial isolates.d) Strictly adhering to established hospital guidelines for cleaning the theatre after refurbishment and on infection control in operating theatres of the hospital.e) Conduct large study to isolate large number of isolates including Aerobic and anaerobic bacteria to obtain more statistically significant results.f) Conduct studies to determine the incidence of SSIs in various hospital setups to observe how could SSI incidence rate varies from hospital to hospital and to determine what could be the factors contributing to the variations in incidence rates in different hospital setups.g) Perform an audit covering all operation theatres of the hospital to determine operation theatre environment itself could be a contributing factor to the development of SSIs as well as to affirm whether the hospital operating staff is strictly adhered to the set up guidelines on infection control in the hospital.h) Conduct studies to determine the mechanisms for harbouring antimicrobial resistance pathogens in Sri Lankan clinical setup.i) Limit use of antibiotics that show highly resistance by commonly isolated bacterial isolates within the institution.j) Review guidelines recommended by WHO or CDC like international institutions to modify current guidelines followed by the hospital.k) Establish continuous surveillance studies to identify antimicrobial susceptibility pattern of bacteria that are commonly isolated within the institution.l) Well maintenance of hospital records to tract patients easily in case of back tracking is needed for the future studies conducted in the hospital.m) Closely monitor the patients who are having diabetes mellitus, hypertension and dyslipidaemia before & after to the surgery. n) More attention should be given to the patients who are in age group > 60 years.