European Journal of Cardiovascular Medicine

Surgical Site Infections (SSIs) are among the most prevalent healthcare-associated infections (HAIs), significantly contributing to postoperative morbidity, prolonged hospitalization, increased costs, and mortality.[1]

According to the CDC, SSIs account for nearly 20–25% of all all hospital-acquired infections and are associated with a two- to eleven-fold increase in mortality risk, in addition to higher healthcare expenditure and extended hospital stay. [2,3]

SSIs not only adversely affect patient recovery but also place a substantial burden on the healthcare system.

SSIs are defined as infections occurring within 30 days after surgery or within one year if an implant is left in place after the procedure and affects either the incision or deep tissue at the operation site. [4]

The consequences of SSIs include prolonged hospital stay, delayed wound healing, additional surgical interventions, increased use of antibiotics, and higher healthcare costs. These factors contribute to both social and economic losses for patients and their families. [5,6]

Numerous patient-related risk factors are implicated in SSI development, including advanced age, obesity, diabetes mellitus and nutritional status. [7] Surgical factors such as prolonged duration of surgery, emergency operations, wound contamination, and complex surgical interventions also contribute substantially to SSI occurrence. [8,9]

A systematic review of observational studies demonstrated that comorbidities, advanced age, and surgery complexity were consistent predictors of SSI. Diabetes was found to increase SSI risk with odds ratios ranging from 1.5 to 24.3, while longer surgery duration also showed significant association (median OR ~2.3). [9] With the rising challenge of antimicrobial resistance, timely antibiotic prophylaxis and identification of causative organisms are critical.

This study aimed to evaluate local epidemiological data on the prevalence of SSIs, associated risk factors, timing of antibiotic prophylaxis, and microbiological profile of isolates in a tertiary care hospital of a tribal state of India for developing evidence-based infection prevention strategies.

This observational cross sectional study was conducted in the Department of General Surgery, Department of General Surgery, Tomo Riba Institute of Health and Medical Sciences (TRIHMS), Arunachal Pradesh, India, for a period of 1 year. The study was carried out after obtaining approval from the Institutional Ethics Committee, Tomo Riba Institute of Health and Medical Sciences (TRIHMS). Strict confidentiality and privacy were maintained.

As per the convenience sampling technique, all the cases admitted to the surgical wards (including both elective and emergency surgery) during the study period and those who met the eligibility criteria were included in the study. All patients, older than 18 years who were admitted in the Department of General Surgery, TRIHMS within the study period of 1 year for different surgical procedures and developed surgical site infection after 48 hours of surgery were eligible for the study. The patients who would have a second surgery at the same site for any reason or on immunosuppressant therapy or immunodeficiency disease, patients who are already on antibiotics for infections elsewhere and unwilling to participate and follow study protocol were excluded from the study. Information regarding demographic characteristics, comorbidities, surgical category, duration of surgery, drain usage, hospital stay, and BMI were recorded. Timing of antibiotic prophylaxis was noted.  The patients were monitored postoperatively for signs of surgical site infections including postoperative fever, throbbing pain around the wound site and wound site examination was done for erythema, induration, serous or serosanguinous discharge after 48 hours of surgery. Type of surgical site infection was noted and the wounds were classified according to Centres for Disease Control and Prevention (CDC) classification. Samples from infected sites were collected aseptically and processed in the microbiology laboratory. Identification of bacterial isolates was performed using standard culture and biochemical methods. Patients were followed up for a period of 30 days post-surgery.

Statistical Analysis: The data obtained were entered in Microsoft Excel and the results were

analysed using SPSS (Statistical Package for the Social Sciences) 22.0, and R environment ver.3.2.2. Descriptive and inferential statistical analysis has been carried out in the present study. Data were presented in tables as frequencies and percentages.

A total 2050 of patients underwent different types of surgeries, including elective as well as emergency procedures, during the study period. About 500 SSIs were documented, and hence, the overall prevalence of SSI rate during the study period was 24.4% (n = 2050).

62.2% (311) of the patients with SSI were Diabetic. Overweight (150) and obese (112) individuals constituted of 30% and 22.4 % respectively. (Table 1, 2)

Among the affected patients, males constituted 230 (46%), while females accounted for 270 (54%). The highest incidence of SSIs was observed in the 22–29 years age group (24.8%), followed by patients aged above 60 years (22.4%). A majority of SSIs were observed in emergency surgeries (408; 81.6%), while elective procedures accounted for only 92 (18.4%). With respect to wound classification, dirty wounds contributed the largest share (47.8%), followed by contaminated (36.2%), clean-contaminated (11.6%), and clean wounds (4.4%). Surgery duration was also found to be significant, as 78.4% of SSIs occurred in procedures lasting >2 hours, compared to 21.6% in surgeries <2 hours. The use of surgical drains was associated with SSIs in 130 patients (26%). Furthermore, prolonged hospital stay (>2 days) was noted in 308 patients (61.6%), indicating a relationship with SSI occurrence. (Table 3)

Only a minority of patients received antibiotics in the recommended preoperative period (102; 20.4%). A further 22 patients (4.4%) received prophylaxis perioperatively, while the majority (376; 75.2%) were administered antibiotics postoperatively, reflecting poor adherence to established prophylaxis guidelines. (Table 4)

Out of 161 wound swabs and pus cultures that yielded growth, Pseudomonas aeruginosa was the most common isolate (42.2%), followed by Staphylococcus aureus (29.8%), Escherichia coli (13.6%), and Klebsiella pneumoniae (8%). Less common pathogens included Streptococcus milleri (3%) and Acinetobacter spp. (3%). (Table 5)

Table 1. SSIs in Relation to Diabetes Mellitus

Table 2. SSI according to BMI

Table 3: Factors associated with Surgical Site Infections

Table 4. SSI according to timing of antibiotic prophylaxis

Table 5. Bacterial isolates from patients with positive culture from surgical site

The present study demonstrated a 24.4% prevalence of surgical site infections (SSIs), which is considerably higher than the incidence reported in studies done by Kumar et al., Al-Mulhim et al. and Mohan et al. ^[10,11,12] However, similar high rates have been observed in many other studies, ranging from 11% to 26% .^[13,14] The elevated prevalence in our setting could be attributed to inadequate infection control measures, poor compliance with antibiotic prophylaxis guidelines, and the high proportion of emergency surgeries.

In the current study, SSIs were more common among diabetic patients (62.2%), consistent with previous reports that diabetes mellitus significantly increases SSI risk due to impaired wound healing, poor tissue perfusion, and altered immune response. ^[15,16] Similarly, a higher incidence was observed among overweight and obese patients, aligning with evidence that increased adipose tissue compromises vascularity, leading to poor antibiotic penetration and delayed wound healing.^[17]

A slightly higher prevalence was noted among females (54%), which is in agreement with some studies, ^[18] but in contrast, a study done by Shanmugam et al. ^[19] reported almost equal occurrences among females (52%) and males (48%) [20] and Mohan et al. ^[12] reported a significantly higher rates in male.

In the present study 22–29 years age group had the highest proportion of SSIs reported, followed by patients >60 years. This could be because younger patients often undergo emergency abdominal and obstetric procedures, while older age is a recognized risk factor due to comorbidities and compromised immunity. ^[20]

The majority of SSIs in this study were associated with emergency procedures (81.6%), The increased rate of SSI in emergency surgeries may be due to a very narrow time span without proper patient preparation and surgical preparedness as well as contaminated wounds as in cases of road traffic accidents. Previous studies have similarly shown that emergency surgeries carry a 2–3 times higher SSI risk compared to elective procedures. ^[21,22]
Wound classification was consistent with CDC’s classification system correlating higher contamination levels with increased SSI risk, with dirty and contaminated wounds contributing the largest share. Longer surgical duration (>2 hours) was another important determinant, as extended operating times increase the risk of microbial contamination and tissue trauma. ^[23,24].

The use of surgical drains was associated with SSIs in 26% of cases, in line with earlier studies showing drains can act as a nidus for infection ^[25]

Additionally, prolonged hospital stay (>2 days) was associated with more SSI in our study suggesting longer stays can increase exposure to nosocomial pathogens as well as these infections lengthen admission duration.^[13]

Only 20.4% of patients in this study received preoperative antibiotics as recommended, while the majority received them postoperatively. Evidence strongly suggests that prophylaxis is most effective when given within 60 minutes before incision, and delayed administration fails to reduce SSI risk. ^[23,26] This highlights the need for strict adherence to institutional protocols.

The most common isolate was Pseudomonas aeruginosa (42.2%), followed by Staphylococcus aureus (29.8%). While S. aureus is widely reported as the predominant SSI pathogen globally ^[4], several Indian and regional studies have reported a rising incidence of Pseudomonas and Gram-negative infections, reflecting local microbiological ecology and hospital antibiotic practices. ^[14,27] The predominance of resistant Gram-negative organisms poses significant challenges for treatment and emphasizes the importance of targeted antibiotic stewardship programs.

The findings of this study highlight the multifactorial nature of SSIs, involving patient comorbidities, surgical practices, wound classification, and microbiological factors. Identification of the risk factors for development of SSI and the necessary steps to halt the progression in-case of any elective or emergency surgical procedures should be prioritized. Improving infection control practices, optimizing perioperative care, and enforcing rational antibiotic policies are essential to reducing the burden of SSIs.

This study revealed a high prevalence of surgical site infections (24.4%), substantially greater than rates reported in high-income countries. Several factors were identified as significant contributors, including diabetes mellitus, obesity, prolonged surgical duration, emergency procedures, dirty/contaminated wounds, use of surgical drains, and prolonged hospital stay. Importantly, inappropriate timing of antibiotic prophylaxis was observed in the majority of patients, which may have further contributed to the elevated SSI rates. The microbiological profile highlighted the predominance of Gram-negative organisms, particularly Pseudomonas aeruginosa, followed by Staphylococcus aureus, reflecting a concerning trend in antimicrobial resistance.

SSIs remain a major cause of morbidity, prolonged hospitalization, and increased healthcare costs. Strengthening infection prevention protocols and adopting evidence-based perioperative practices are essential to reduce the SSI burden in resource-limited settings.

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