Healthcare-associated infections (HAIs) are acquired by patients during care, originating from either exogenous sources or the endogenous flora of patients. They are the most frequent adverse event that compromises patient safety globally. Research from the World Health Organization's (WHO) ‘Clean Care is Safer Care’ program indicated that surgical site infections (SSI) are the most monitored and prevalent type of HAI, accounting for 20% of all HAIs. The burden is even greater in low- and middle-income countries (LMICs), affecting up to one-third of patients who have undergone surgical procedures. [1]

SSI are defined as infections that occur at the surgical site within 30- or 90-days post-surgery. They are classified into superficial incisional (within 30 days), deep incisional SSI, and organ/space SSI (within 30 or 90 days). Both superficial and deep incisional SSI are further divided into primary and secondary categories. [2] According to the 2023 HAI data results, the SSI standardized infection ratio (SIR) for all National Health Safety Network (NHSN) operational procedure categories combined increased by almost 2% from the previous year. Although there is no national benchmark data, several multicentric investigations revealed SSI rates ranging from 1.6% to as high as 38% in India. [3] They continue to be a major source of morbidity, mortality, extended hospital stays and significant financial burden. Among patients who develop SSI, these infections are directly associated with 75% of deaths and a 2- to 11-fold increase in mortality risk. [2]

Staphylococcus aureus (S. aureus) has historically been the most frequently isolated bacterium from surgical site infections (SSI) wounds. [4] However, recent data indicates that multidrug-resistant (MDR) Gram-negative (GN) bacteria, such as Pseudomonas aeruginosa (P. aeruginosa) and Acinetobacter calcoaceticus-baumannii complex (A. baumannii), are increasingly being isolated from SSI. [5]

The risk factors leading to the development of SSI can be patient-related (elderly, presence of co-morbidities, immunosuppression, duration of hospital stay, smoking, obesity/malnutrition, coexistence of infections, etc.), procedure-related (poor surgical technique, improper sterilization of the instruments, prolonged duration of surgery, inadequate antimicrobial prophylaxis, etc.), organism-related (inoculum size, bacterial virulence, biofilm formation), and environmental-related. [6]

Quantifying the burden of SSI and ensuring surveillance is essential. Understanding current infection control guidelines and their practice is necessary to identify existing gaps. 

This study aimed to determine the (i) extent of SSI across various surgical specialties, (ii) demographic characteristics, (iii) associated risk factors (iv) distribution of predominant pathogens, and (v) their antimicrobial resistance (AMR) patterns, at a tertiary-care hospital in Eastern India. 

This was a descriptive, cross-sectional study conducted in the Department of Microbiology covering a period of 24 months (January 2023 to February 2025), at tertiary-care teaching hospital in Eastern India.

All SSI cases according to guidelines by Centers for Disease Control and Prevention (CDC) NHSN criteria were included in this study, irrespective of age and gender. [2] Infections at the surgical site occurring more than 30 days post-operative are excluded from the study, except for breast, implant, and joint surgeries.

The study was conducted in conformity with all ethical guidelines. The protocol was reviewed and approved by the Institutional Ethics Committee. Patient confidentiality was maintained throughout the study by de-identifying all collected data.

A total of 6,628 surgeries were conducted during this period, with 358 confirmed cases of SSI (SSI rate:5.4%). The SSI rate was highest in the orthopaedics department (7.8%), followed by plastic surgery (7.2%) and obstetrics and gynaecology departments (6.4%) [Table. 1]. The categories of SSI cases across various departments are compiled [Table. 2]. Superficial, deep, and organ/space SSI accounted for 28% (N=99), 62% (N=223), and 10% (N=36) of the total cases, respectively. 

About 60% were males (n=214), with a sex ratio of 1.5:1. The highest incidence of SSI was noted in the 31-40 years age group (n=86, 24%) [Fig. 1]. Smoking (48%) was the most prevalent risk factor [Fig. 2].

Microbiological confirmation was observed in 87% (n=312) of the SSI cases, of which 67% (n=240) exhibited monomicrobial growth and 20% (n=72) showed polymicrobial growth. A total of 324 pathogens were isolated during the study period where GN and Gram-positive (GP) bacteria constituted 65.4% (n=212) and 34.6% (n=112) of the isolates, respectively. Among GP, S. aureus comprised of the majority (n=78, 70%). Escherichia coli (E. coli) (n=59,28%) was the predominant pathogen among GN, followed by Klebsiella spp. (n=49, 23%), P. aeruginosa (n=46, 21.6%), A. baumannii (n=33, 15.6%), Proteus spp. (n=15, 7%) and others (n=10, 5%) [Table. 3].

Despite considerable advancements in infection control, surgical, and sterilization techniques within healthcare settings, SSIs remain a significant burden. The rise of high AMR among pathogens has further complicated management and treatment. [8]

Overall, the SSI rate in our study was 5.4%, aligning with studies by Hirani S et al. (5.6%), Karan et al. (5.5%) and Mohan et al. (5.5%). [8, 9, 10] However, studies by Negi V et al. and Verma U et al. reported a high infection rate of 17.5% and 37.1%, respectively. [11, 12] The neglect of infection control practices, improper hand hygiene practices, and overcrowded hospitals are significant contributing factors to the high infection rates in India. [11] 

Male preponderance was observed in our study, corresponding with several other studies. [11, 13, 14] A higher proportion of SSI was observed in the age group of 31-40 years (24%), followed by 41-50 years (17.3%). The increase in the incidence of SSI with age, as also evident in other studies, may be attributed to low immunity, delayed wound healing, diminished physiological defence, and the presence of co-morbidities. [15] Conversely, a study by Mohan et al. noted a greater number of SSI cases in individuals below 25 years. [10]

Smoking was the primary risk factor identified in our study (48%). It leads to the constriction of peripheral blood vessels, resulting in tissue hypovolaemia and hypoxia, which interferes with wound healing. [6] Anaemia (36%) and diabetes mellitus (32%) were the main associated co-morbidities in our study, concurring with the findings from Kasukurthy LR et al. and Choudhury K et al. [15, 16] Approximately 24% of patients who underwent emergency procedures developed SSIs. This may be due to a very limited time frame lacking adequate patient preparation, surgical readiness, or the presence of contaminated wounds, as seen in cases of road traffic accidents.

Maximum SSI was recorded in the orthopaedics department (7.8%), in tandem with a study Khan AS et al (3.4%). [17] This was followed by plastic surgery (7.2%), and obstetrics and gynaecology department (6.4%). Studies by Banik et al. (8.22%) and Choudhury et al. (4.8%) reported highest infection rate in plastic surgery whereas Pham JC et al. reported the maximum in general surgery. [13, 15, 18] Given the potential for implant or graft rejection, a higher percentage of SSIs in orthopaedics and plastic surgery departments is concerning. Deep SSI accounted for the majority of the SSI (62%), corresponding with a few other studies.[10, 13] However, Kumar A et al. reported that the incidence of superficial SSIs was the highest. [19]

In our study, culture-positivity rate was 87%, corresponding with Choudhury et al (84.55%) and Dhote et al (92%). [15, 20] Of this, 67% exhibited monomicrobial growth and 20% were polymicrobial, showing similarity with many other studies. [13, 16, 21] A few studies reported lower culture positivity rates (Khan AS et al: 52%, and Kokate et al.: 49.5%). [17, 22] Polymicrobial infections present challenges due to their requirement for higher classes of antimicrobials and extended treatment durations. 

*IR: Intrinsic resistance

GN organisms (65.4%) were isolated more frequently than GP organisms (34.6%) in this study. Consistent with majority of studies, our research also showed S. aureus to be the most prevalent isolate (70%) among GP organisms and E. coli (28%) among GN organisms. [10, 11, 14, 15, 17] Contrary to previous reports, recent investigations had observed the emergence of non-fermenters like P. aeruginosa and A. baumannii as emerging pathogens of SSI. [23] 

The antimicrobial profile of majority of the organisms showed a high prevalence of resistance. GP organisms exhibited maximum resistance to penicillin (81%), corroborating with a study Banik A et al. (95%).[11] A sizable fraction of the S. aureus isolates exhibited methicillin resistance (MRSA) (45%), which is higher when compared to studies by Negi V et al. (15.7%) and Choudhury K. et al (39.29%) but lower than Patnaik et al (52.3%). [11, 15, 24] Increased MRSA isolation from SSI samples suggests that infection 

control procedures need to be improved. Vancomycin, linezolid, teicoplanin were found to be most effective antimicrobials for S. aureus and daptomycin was the most effective for Enterococcus spp, consistent with the findings by Verma U et al. and Choudhury et al. [12, 15]

GN organisms were predominantly resistant to cephalosporins and fluoroquinolones, aligning with the findings of Banik A et al. [11] The carbapenem resistance among Enterobacterales detected in our study was 46.4%, which is higher than a study by Banik A et al. (34.78%). [11] This may be attributed to the imprudent use of meropenem as the first line of empirical treatment. Lower rates of resistance were noted for carbapenems and β-lactam/β-lactamase inhibitor (BL/BLI) combination in a study conducted by Negi V et al. [11]

A comparison of SSI rate among various studies across India, along with important resistance among isolates is compiled in [Table. 7]. Before every procedure, all cases had received prophylactic antimicrobials in our study. The most widely used drug was a third-generation cephalosporin. The findings of the antimicrobial susceptibility test, however, indicated that the isolated bacterial strains exhibited a high degree of resistance to this agent. The frequent empirical administration of this antimicrobial both for therapeutic and preventative purposes in our hospital may have contributed to the high level of resistance.

A study by Aghdassi et al. found a significant increase in SSI caused by GNB during warmer months, suggesting a link between temperature and SSI risk. This has important implications for SSI prevention strategies, which should consider the influence of temperature and climate factors. Therefore, underlying changes in microbiome composition brought on by climatic conditions should be included in future investigations. [25]

Surgical site infections (SSI) remain a significant clinical challenge despite rapid advancements in technology and knowledge. The elevated SSI rates across various departments underscore the critical need for enhanced stringent infection control protocols and robust antimicrobial stewardship within our hospital. A paradigm shift in bacteriological profiles, from GP to MDR GN organisms, poses a serious threat to patient outcomes and significantly impedes surgical progress.[26] Therefore, understanding the local microbial epidemiology is crucial for guiding appropriate empirical treatment. Regular surveillance of SSI cases, including their risk factors and timely feedback, is essential for reducing prevalence. To effectively combat the rising incidence and complexity of SSI, a proactive strategy is paramount, encompassing rigorous auditing of surgical antimicrobial prophylaxis protocols and consistent, periodic resistance trend analysis. Evidence strongly supports these practices in optimizing antimicrobial use.[27, 28] This enables timely adjustments to empirical treatment strategies and minimizes selective pressure for resistance, thereby improving patient outcomes and contributing to broader antimicrobial stewardship efforts.

Acknowledgement: Authors are grateful to the technical staffs of Microbiology laboratory for their consistent help in conducting the study.

Declaration of patient consent: The authors attest to having acquired all required patient permission documents. The patients had grant permission for the journal to publish his or her clinical data. They are aware that due efforts will be made to conceal their identity.