Surgical-site infection (SSI) is an infection involving the operative incision or the manipulated organ or anatomical space after a surgical procedure. It remains an important indicator of surgical quality because it increases postoperative morbidity, delays recovery, and consumes substantial healthcare resources. A 2023 systematic review and meta-analysis estimated a pooled global SSI incidence of 2.5%, although the burden varied markedly across regions, surgical specialties, surveillance systems, and patient populations.¹ Abdominal operations carry a greater infection risk than many other procedures because they frequently involve entry into the gastrointestinal or biliary tract, exposure to endogenous microorganisms, extensive tissue handling, and prolonged operative time.

Marked disparities in SSI occurrence have been reported between healthcare settings. The GlobalSurg Collaborative documented infection rates of 9.4%, 14.0%, and 23.2% after gastrointestinal surgery in high-, middle-, and low-human-development settings, respectively.² These differences reflect variation in case complexity, antimicrobial resistance, infrastructure, perioperative practices, and access to follow-up. Evidence-based recommendations from the Centers for Disease Control and Prevention and the World Health Organization emphasize appropriate antimicrobial prophylaxis, alcohol-based skin preparation, perioperative glycaemic control, maintenance of normothermia, adequate oxygenation, and standardized surveillance.^3,4 Despite these measures, SSIs continue to occur and frequently become evident after discharge, making 30-day follow-up essential for reliable estimation.

The consequences extend beyond wound-related symptoms. Infected patients can require repeated dressings, antimicrobial therapy, drainage, secondary suturing, readmission, or reoperation. A systematic review demonstrated that SSI is consistently associated with longer hospitalization, higher treatment costs, and impaired patient outcomes.⁵ Prevention therefore depends on recognizing modifiable factors before and during surgery. Reported patient-related determinants include advanced age, diabetes, obesity, smoking, anaemia, malnutrition, and higher American Society of Anesthesiologists physical status. Procedure-related factors include an open approach, prolonged operative duration, wound contamination, blood loss, drain use, and extended preoperative hospitalization.⁶

Prospective abdominal-surgery cohorts have reported substantial variability in incidence and predictors. An incidence of 16.3% was recorded in a prospective cohort from Saudi Arabia, with open surgery and longer operative duration identified as independent predictors.⁷ Indian studies have reported rates ranging from 8% in planned abdominal operations to 39% in selected rural surgical populations, demonstrating the importance of local case mix, definitions, microbiology, and surveillance intensity.^8,9 Contemporary institution-specific evidence is therefore required to guide focused prevention rather than relying exclusively on pooled estimates.

The present study was conducted to determine the incidence and types of SSI following elective abdominal surgery, describe the associated microbiological profile and postoperative outcomes, and evaluate patient-related and perioperative risk factors associated with infection. The primary objective was to identify independent predictors of SSI within 30 postoperative days; the secondary objectives were to characterize infecting organisms and compare postoperative hospital stay and infection-related interventions between patients with and without SSI.

Study design and setting This prospective hospital-based observational study was conducted in the Department of General Surgery, Gandhi Medical College, Secunderabad, Telangana, India, from November 2024 to April 2025. The study followed the principles of the Declaration of Helsinki and observational reporting recommendations. Necessary Permissions were obtained before starting the study and written informed consent was obtained from every participant before enrolment. Study population Consecutive patients aged 18 years or older who underwent elective abdominal surgery during the study period were screened. Eligible procedures included hernia repair, cholecystectomy, colorectal surgery, gastric surgery, hepatobiliary surgery, and other planned intra-abdominal operations. Patients undergoing emergency surgery, those with active infection at the proposed incision, established systemic sepsis, incomplete perioperative records, or inability to complete 30-day follow-up were excluded. Of 106 patients assessed, 100 fulfilled the criteria and completed follow-up. Sample size and sampling Assuming an anticipated SSI frequency of 20%, a 95% confidence level, and 8% absolute precision, the minimum sample size calculated using n = Z²pq/d² was 96. The final sample was rounded to 100. Participants were enrolled through consecutive sampling to reduce selection arising from discretionary recruitment. Data collection and definitions A structured case-record form was used to document age, sex, body mass index, diabetes, hypertension, anaemia, current smoking, American Society of Anesthesiologists physical-status grade, and preoperative hospital stay. Obesity was defined as body mass index ≥30 kg/m². Anaemia was defined as haemoglobin <13 g/dL in men or <12 g/dL in women. Operative variables included procedure type, open or laparoscopic approach, operative duration, and drain placement. Standard institutional protocols were followed for antimicrobial prophylaxis, skin preparation, asepsis, and postoperative wound care. Outcome assessment The primary outcome was SSI occurring within 30 days of surgery. Infection was classified as superficial incisional, deep incisional, or organ-space infection using established surveillance definitions.10 Wounds were examined during admission and at scheduled postoperative reviews. Patients were instructed to report discharge, increasing pain, erythema, swelling, fever, or wound separation. Samples from clinically infected wounds were collected aseptically before modification of antimicrobial therapy whenever feasible and processed using routine culture and identification methods. Risk assessment incorporated established patient and operative constructs used in surgical surveillance.11 Statistical analysis Continuous variables were summarized as mean ± standard deviation or median with interquartile range, while categorical variables were expressed as frequencies and percentages. The chi-square test was used for categorical comparisons; Fisher’s exact test was applied when expected cell counts were below five. Postoperative stay was compared using an independent-samples t-test. Unadjusted odds ratios were calculated. Because 18 SSI events occurred, the exploratory multivariable logistic model was restricted a priori to three clinically relevant predictors to reduce overfitting. Adjusted odds ratios with 95% confidence intervals were reported. A two-sided p-value <0.05 was considered statistically significant.

Participant recruitment

During the study period, 106 patients scheduled for elective abdominal surgery were assessed for eligibility. Six patients were excluded: four did not fulfil the eligibility criteria and two declined participation. The remaining 100 patients were enrolled and included in the final analysis. Complete perioperative and 30-day postoperative follow-up data were available for all participants.

Demographic, clinical, and operative characteristics

The mean age of the participants was 49.7 ± 14.8 years, with a range of 18–78 years. Twenty-eight (28.0%) patients were aged 60 years or older. Fifty-six (56.0%) participants were male and 44 (44.0%) were female. The mean body mass index was 26.4 ± 4.2 kg/m², and obesity was present in 30 (30.0%) patients. Diabetes mellitus was documented in 28 (28.0%), hypertension in 32 (32.0%), anaemia in 24 (24.0%), and current smoking in 26 (26.0%). Open abdominal surgery was performed in 62 (62.0%) patients, 35 (35.0%) procedures lasted longer than 120 minutes, and a surgical drain was placed in 40 (40.0%) patients (Table 1).

Table 1. Demographic, clinical, and operative characteristics of the participants

Values are presented as mean ± standard deviation or number (percentage). ASA: American Society of Anesthesiologists.

Distribution of surgical procedures

Hernia repair was the most frequently performed procedure, accounting for 28 (28.0%) cases, followed by cholecystectomy in 22 (22.0%), colorectal surgery in 18 (18.0%), gastric surgery in 12 (12.0%), hepatobiliary surgery in 10 (10.0%), and other elective abdominal procedures in 10 (10.0%).

Incidence and characteristics of surgical-site infection

Surgical-site infection developed in 18 patients, giving an overall incidence of 18.0%. Superficial incisional infection was the most frequent type and occurred in 11 (61.1%) affected patients. Deep incisional infection occurred in five (27.8%), while two (11.1%) developed organ-space infection. The median interval from surgery to diagnosis was 6 days (interquartile range, 4–8 days). Twelve infections were identified during the initial admission and six during follow-up. Wound cultures were positive in 15 (83.3%) infected patients. Staphylococcus aureus was the predominant isolate, followed by Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Enterococcus species (Table 2).

Table 2. Clinical and microbiological profile of surgical-site infections

Percentages for infection type were calculated using 18 patients with SSI; percentages for isolates were calculated using 15 culture-positive cases. SSI: surgical-site infection.

Factors associated with surgical-site infection

SSI occurred more frequently among patients aged 60 years or older than among younger patients (32.1% versus 12.5%; p=0.022). The infection rate was also higher in patients with diabetes than in those without diabetes (35.7% versus 11.1%; p=0.004). Obesity, current smoking, anaemia, ASA grade III, open surgery, operative duration longer than 120 minutes, drain placement, and preoperative hospitalization exceeding 2 days were significantly associated with SSI on univariate analysis (Table 3).

Table 3. Univariate analysis of factors associated with surgical-site infection

*Fisher’s exact test; remaining comparisons used the chi-square test. ASA: American Society of Anesthesiologists; OR: odds ratio; SSI: surgical-site infection.

Multivariable analysis

In the exploratory multivariable model, diabetes mellitus, operative duration longer than 120 minutes, and preoperative hospital stay longer than 2 days remained independently associated with SSI. Diabetes was associated with 3.62-fold higher adjusted odds of infection, while prolonged surgery and extended preoperative hospitalization increased the adjusted odds by 3.21-fold and 3.44-fold, respectively (Table 4).

Table 4. Exploratory multivariable logistic regression analysis of independent risk factors for surgical-site infection

OR: odds ratio. The model was restricted to three clinically relevant predictors because only 18 SSI events occurred.

Postoperative outcomes

Patients who developed SSI had a significantly longer mean postoperative hospital stay than those without infection (12.8 ± 4.9 versus 6.7 ± 2.6 days; p<0.001). Three infected patients required secondary wound closure, and the two patients with organ-space infection underwent image-guided drainage. No SSI-related mortality was recorded during the 30-day follow-up period.

The present study identified an overall SSI incidence of 18.0% after elective abdominal surgery. This rate is close to the 16.3% reported by Alkaaki et al. in a prospective abdominal-surgery cohort and the 17% overall incidence reported by Jatoliya et al. in an Indian tertiary hospital.^7,9 It is higher than the 8% reported for the planned-surgery subgroup in the latter study but lower than the 39% superficial SSI incidence observed in a rural Central Indian cohort.^8,9 Differences in procedure mix, wound classification, referral patterns, perioperative protocols, and post-discharge surveillance plausibly account for this variation. The observed rate also lies between estimates reported for middle- and low-human-development settings in the GlobalSurg study.²

Superficial incisional infection was the predominant category, representing 61.1% of SSIs. This pattern is expected because superficial infections are readily detected during wound examination and are frequently associated with skin flora. Staphylococcus aureus was the leading isolate, whereas Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Enterococcus species reflected the mixed endogenous and healthcare-associated microbial exposure of abdominal surgery. Similar studies have reported skin organisms and enteric Gram-negative bacilli, with distribution influenced by the operated organ, prophylactic regimen, and local resistance ecology.^7,9 Culture positivity in 83.3% supports obtaining appropriate specimens before changing antibiotics whenever the clinical condition permits.

Diabetes mellitus was the strongest independent patient-related predictor. Hyperglycaemia impairs neutrophil chemotaxis, phagocytosis, microvascular perfusion, and collagen formation, thereby weakening local defence and wound repair. Ata et al. demonstrated a clinically important association between postoperative hyperglycaemia and SSI in general surgical patients.¹³ Preoperative identification of diabetes, perioperative glucose monitoring, and avoidance of pronounced hyperglycaemia are therefore practical preventive targets. Obesity, smoking, anaemia, advanced age, and ASA grade III were associated with infection on univariate analysis, consistent with the multifactorial risk profile summarized by Marzoug et al.⁶ Obesity increases wound tension, tissue hypoperfusion, and operative depth; Winfield et al. also reported greater SSI risk in obese patients undergoing abdominal procedures.¹²

Operative duration longer than 120 minutes independently increased SSI risk. Longer procedures entail greater tissue exposure, repeated instrument contact, physiological stress, and opportunities for contamination. A preoperative stay exceeding 2 days was also independently associated with infection, potentially reflecting greater exposure to hospital flora and delayed optimization. Open surgery and drain placement showed univariate associations but did not remain in the restricted adjusted model. These findings support efficient operative workflow, avoidance of unnecessary preoperative admission, careful drain selection, and minimally invasive approaches when clinically appropriate.

SSI substantially prolonged postoperative hospitalization, from 6.7 to 12.8 days. This accords with evidence showing that SSI increases resource use, treatment costs, and recovery time.⁵ Prevention should combine patient optimization with reliable antibiotic timing, skin antisepsis, normothermia, glycaemic control, aseptic technique, and post-discharge surveillance. Current acute-care guidance favours bundled implementation and regular feedback of SSI data to surgical teams.^3,4,14

LIMITATIONS

This study was conducted at a single tertiary-care centre with a modest sample and only 18 SSI events, limiting precision and producing wide confidence intervals. The exploratory regression model was restricted to three predictors and remains vulnerable to residual confounding and overfitting. Glycaemic measurements, nutritional biomarkers, wound class, antibiotic timing, and antimicrobial resistance patterns were not examined in detail. Thirty-day surveillance could miss infections treated at other institutions.

Surgical-site infection occurred in 18% of patients undergoing elective abdominal surgery and was predominantly superficial incisional. Staphylococcus aureus was the most frequent isolate, although enteric Gram-negative organisms also contributed substantially. Diabetes mellitus, operative duration exceeding 120 minutes, and preoperative hospitalization longer than 2 days were independent predictors of infection. SSI nearly doubled the postoperative hospital stay and occasionally required secondary wound closure or image-guided drainage. These findings support systematic preoperative risk assessment, optimization of diabetes and anaemia, reduction of avoidable admission time, efficient operative conduct, rational drain use, and standardized infection surveillance through 30 days. Institution-specific prevention bundles and regular outcome audits are essential to reduce postoperative morbidity and resource utilization.

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2. GlobalSurg Collaborative. Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study. Lancet Infect Dis. 2018;18(5):516-525. doi:10.1016/S1473-3099(18)30101-4.
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