Evaluation of the Bacteriological Profile of Surgical Site Infections: An Observational Study

Background: Healthcare associated infection (HAI) poses major problem for doctors as well as patients and community at large. Among health care associated infections, surgical site infections are the second most common after urinary tract infection. Aim: The aim of the present study was to identify bacterial aetiology of surgical site infections. Material and methods: The study was a prospective, observational study which was carried in the Department of Microbiology, MGM Medical College and LSK Hospital, Kishanganj, Bihar, India.from February 2019 July 2020. A total of 390 patients with clinically diagnosed surgical site infection were chosen for the study. Suitable specimens from all these patients were subjected to Gram staining and culture on suitable culture media, and isolates were identified by colony characters and the battery of standard biochemical tests. All the isolates were tested for antimicrobial susceptibility by Kirby Bauer disk diffusion technique on Muller Hinton Agar. Results: Out of 390 samples, 200 samples yielded positive culture (51.28%). Out of the positive samples Staphylococcus aureus (27.5%) was the most common pathogen isolated followed by Escherichia coli (22%), Citrobacter spp. (15%) and Pseudomonas aeruginosa (12.5%). Conclusion: We conclude that the surgical site infections caused by Gram positive and Gram negative bacteria continue to be a frequent complication of surgical interventions. As the increasing resistance to antimicrobials increases the risk of morbidity and mortality, there is an urgent need for implementation of measures to restrict the health care associated infections. Introduction Infections which occur during the time of hospital stay and were not present or in incubating stage, during the time of hospital admission are considered as health care associated infections (HAI). HAI poses major health problem for both doctors as well as patients. Health care associated infections prolong hospital stay which leads to financial burden to the patients and also increases the mortality and morbidity. It has been reported that in United States of America the annual mortality is about 88,000 despite the annual estimated cost of management of HAI of about 4.5 billion dollar. Among the health care associated infections, Surgical Site Infections (SSI) are the second most common after Urinary Tract Infection European Journal of Molecular & Clinical Medicine (EJMCM) ISSN: 2515-8260 Volume 07, Issue 10, 2020 3920 (UTI). SSI are a common complication associated with surgery, with a reported incidence rates of 2-20%. They are responsible for increasing the treatment cost, length of hospital stay, and significant morbidity and mortality. Despite the technical advances in infection control and surgical practices, SSI still continue to be a major problem, even in hospitals with most modern facilities. These infections are usually caused by exogenous and/or endogenous microorganisms that enter the operative wound either during the surgery (primary infection) or after the surgery (secondary infection). Primary infections are usually more serious, appearing within five to seven days of surgery. Majority of SSI are uncomplicated involving only skin and subcutaneous tissue but sometimes these can progress to necrotizing infections involving the deeper tissues. The usual presentation of infected surgical wound can be characterized by pain, tenderness, warmth, erythema, swelling and pus formation. A number of patient related factors (old age, nutritional status, pre-existing infection, co-morbid illness) and procedure related factors (poor pre-operative part preparation and surgical technique, prolonged duration of surgery, inadequate sterilization of surgical instruments) can influence the risk of SSI significantly. In addition to these risk factors, the virulence and the invasiveness of the organism involved, physiological state of the wound tissue and the immunological integrity of the host are also the important factors that determine whether infection occurs or not. Surveillance data suggest that the types of causative organisms associated with SSI have not significantly changed over the past 10–15 years; however, the proportion of different types of causative organisms has changed. Antimicrobial-resistant organisms are causing an increasing proportion of SSIs, and there has been a rise in the number of infections caused by atypical bacterial and fungal organisms. These changing proportions have been attributed to the increasing acuity of surgical patients, the increase in the number of immunocompromised patients, and the increasing use of broader spectrum antibiotics. SSI continues to be a threat to surgical patients, in spite of the newer antibiotics available today. Although properly administered antibiotics can reduce postoperative surgical site infections secondary to bacterial contamination, widespread use of prophylactic antibiotics can lead to emergence of multidrug resistant bacteria. In developing countries like India, where many hospitals have inadequate infrastructure, poor infection control practices, overcrowded wards and practice of irrational use of antimicrobials, the problem of SSI gets more convoluted. With this background present study was carried out to evaluate the bacteriological profile of surgical site infections in a rural medical college and tertiary care hospital in Northern Bihar. Material and Methods The study was a prospective, observational study which was carried in the Department of Microbiology, Mata Gujri Medical College and LSK Hospital, Kishanganj, Bihar, India. from February 2019 July 2020. Total 390 patients (204 males and 186 females) of all ages with clinical diagnosis of SSI were included in this study. Patients with cellulitis and suture abscess were excluded from this study. Methodology Using sterile cotton swabs, two pus swabs / wound swabs were collected aseptically from each patient suspected of having SSI. Gram stained preparations were made from one swab for provisional diagnosis. The other swab was inoculated on nutrient agar, 5% sheep blood agar (BA) and MacConkey agar (MA) plates and each plate was incubated at 37°C for 24-48 hours before being reported as sterile. Growth on culture plates was identified by its colony characters and the battery of standard biochemical tests. All the isolates were tested for antimicrobial susceptibility by Kirby Bauer disk diffusion technique on Muller Hinton Agar European Journal of Molecular & Clinical Medicine (EJMCM) ISSN: 2515-8260 Volume 07, Issue 10, 2020 3921 and results were interpreted in accordance with Clinical Laboratory Standards Institute (CLSI) guidelines. Antibiotics used for susceptibility testing were: Amikacin, AmpicillinSulbactam, Ceftriaxone, Ciprofloxacin, Gentamicin, Piperacillin-Tazobactum, Imipenem, Azithromycin, Vancomycin, Linezolid, Ofloxacin, Cefoxitin. Statistical Analysis The recorded data was compiled and entered in a spreadsheet computer program (Microsoft Excel 2010) and then exported to data editor page of SPSS version 19 (SPSS Inc., Chicago, Illinois, USA). Descriptive statistics included computation of percentages and means. Results Out of 390 samples, 200 samples were culture positive (51.28%). Among 200 positive samples, 105 (52.5%) were males (Table 1). The age wise distribution of the patients with positive culture has been shown in the (Table 2). The maximum No. of culture positive samples were in the age group of 20-30 years (33%) followed by 30-40 years (17.5 %) and 40-50 years (14%) of age groups respectively. Out of the 200 culture positive samples, Staphylococcus aureus (27.5%) was the most common pathogen isolated followed by Escherichia coli. (22%), Citrobacter spp. (15%) and Pseudomonas aeruginosa (12.5%) (Table 3). Among Gram negative bacilli, isolates of E. coli were found to be most sensitive to Imipenem 93.18%) followed by Amikacin (81.81%) and Piperacillin+Tazobactam (77.27%). For Citrobacter spp. , most of the isolates were sensitive to Imipenem (80%) followed by Gentamicin (50%) and Ciprofloxacin (46.67%). Maximum number of isolates of Klebsiella spp. were found sensitive to Imipenem (73.68%) followed by Gentamicin (47.37%) and Amikacin (47.37%). For Pseudomonas aeruginosa, 64% of the isolates were sensitive to Imipenem, followed by Piperacillin+Tazobactam (60%) amd Gentamicin (52%). For Enterobacter spp. , Imipenem (80%) followed by Amikacin (60%) and Piperacillin+Tazobactam (60%) showed maximum sensitivity (Table 4). Among the Gram positive organisms, isolates of S . aureus showed maximum antibiotic sensitivity to Linezolid (94.54%) followed by Vancomycin (92.72%) and Amikacin (81.82%). The isolates of Coagulase Negative Staphylococci (CONS) were found to be sensitive to Linezolid (100%) followed by Vancomycin (92.85%), and Gentamicin (85.71%) (Table 5). Table 1: Gender-wise Distribution of Culture Positive Patients Gender No of patients (%)