Health care-associated infections (HAIs) remain as an important public health concern. A surgical site infection is an infection that occurs after surgery in the part of the body where the surgery took place, within 30 days, with major discharge of pus or requiring secondary procedure to drain it. ¹³ Surgical site infections can sometimes be superficial infections involving skin, or it can be tissue, deep organ space infection.¹ World Health Organization (WHO) describes hospital acquired infections to be one of the major infectious diseases having a huge economic impact worldwide. These infections affect about 2 million people annually resulting in 5-15% of them requiring hospitalization.¹⁰ it is the second most common complication after surgical procedures (first being post-operative pneumonia) due to virulent bacterial entry, altered wound microenvironment, and changed host defence². A study conducted by Sahane, Bhawal and Lele published in the International Journal

Of Health Sciences records the incidence of SSI as 20% on a population of 300 Obs Gynae patients.³

Whenever an incision, abrasion, cut or burn is inflicted upon the skin, it starts the phase I of inflammation and  switches on the various inflammatory mediators. This is followed by phase II where the phagocytic infiltration and cytokines take the upper hand, which ultimately is controlled by collagen deposition and wound healing. In case of uncontrolled infection, proinflammatory cells release TNF-alpha. This results in over proliferation of phagocytes, acid hydrolase production from lysosomes causing creation of pus filled spaces containing necrotic tissue, neutrophils, bacteria and proteinaceous fluid with all signs of inflammation. This is a typical surgical site infection.²

Gram negative bacilli, namely members of enterobacteriaceae, are the predominant pathogens in a tertiary setup hospital. As per a study conducted on 300 obs gynae patients in a tertiary care hospital, Of the 18 SSI cases, 4 patients’ swabs yielded no growth (22%) aerobically and anaerobically and showed no organisms on direct smear as well. The remaining 14 patients’ swabs yielded a total of 16 isolates in laboratory, of which Escherichia coli was 31.25%, Pseudomonas aeruginosa 25% and Staphylococcus aureus was 22%. This trend of gram negative bacilli i.e. enterobacteriaceae dominating the gram positive cocci has been observed in Aurangabad, Orissa and Navi Mumbai also.³

Several other factors have been seen to influence the nature and incidence of SSIs, the primary ones among them being the comorbid conditions, principally diabetes, anemia , and underlying latent diseases(7.6%) ; the nature of the wound, clean(4.6%), clean contaminated(4.6%), or contaminated(8.0%). The immune status of the patient , age ,  the nature of surgery and surgical instruments and the wound microenvironment also seems to play a role, as stated by a national programme GIRFT(Getting It Right First Time).⁵’⁶ SSI is the index of the health care system in any hospital, as cited by National Beneficiary Survey NBS ROUND 4 .⁷ Though significant research work has been done regarding SSI in the Western world, India, especially Eastern India is in great dearth of such studies which has not only deteriorated the quality of general health but has also led to the misuse of antibiotics leading to their resistance. With the increase in incidence of nosocomial infections and multi drug resistance, a meticulous and periodic surveillance of various hospital acquired infections is called for. The present study is aimed at obtaining the incidence of SSI in our set up and the evaluation of their risk factors and presence of antibiotic resistance. This shall also be beneficial for formulating any kind of antibiotic policy for the patients admitted for surgery in this set up in the near future.⁸

Aims and Objectives

This investigative undertaking was conceptualized with the express intent of elucidating the multifactorial dimensions of surgical site infection (SSI) in the context of abdominal and hernia surgeries conducted within a tertiary-care governmental medical institution in Eastern India. The specific objectives included:

1. To determine the epidemiological burden and proportional magnitude of SSI among patients subjected to abdominal and hernia surgeries over a fixed observational period.
2. To delineate the microbiological spectrum of pathogens implicated in SSIs, with an emphasis on identifying dominant aerobic isolates and assessing the incidence of polymicrobial involvement.
3. To evaluate the phenotypic antimicrobial resistance profiles of cultured pathogens, using WHO AWARE classification schema and Essential Medicines List, thereby mapping drug susceptibility against priority pathogens.
4. To contextualize the socio-demographic and clinical variables that predispose patients to SSIs, establishing associations between host, procedure, and environment-related determinants.
5. To provide foundational data that may inform institutional policies on antibiotic prophylaxis, stewardship, and resistance containment in operative environments.

Study Design and Setting

A prospective, cross-sectional observational study was conducted over a span of six months, encompassing a multidisciplinary integration of the Departments of General Surgery, Microbiology, and Pharmacology at Medical College, Kolkata. The study adhered to ICH-GCP and ICMR guidelines, receiving ethical clearance from the Institutional Ethics Committee (Ref No.MC/KOLAIECNON-SPON/2530/06/2024).

Sample Design and Population

The study cohort was meticulously curated from a captive in-hospital population comprising individuals who underwent abdominal and/or herniorrhaphy interventions within the General Surgery Department of Medical College, Kolkata, over a pre-defined observational period. The patient population thus derived was subjected to rigorous eligibility screening in concordance with the protocol's inclusion and exclusion matrices.

Sample Size Determination and Statistical Justification

The requisite sample size was computed employing classical binomial approximation underpinned by the formula for estimating population proportion with finite precision. Assuming a putative prevalence (P) of 20% (0.20)—based on prior epidemiological benchmarks—and incorporating a Type I error (α) of 8% (0.08) with Zα/2 = 1.96 (standard normal deviate for 95% confidence), and absolute precision (d) = 5% (0.05), the derivation follows thus:

Sample size =

= (1.96)2×0.2× (1−0.2)/      = 96

(0.08)2

To accommodate an anticipated attritional deviation approximated at 5%, the sample size was conservatively inflated to n = 101, ensuring robustness of statistical inference amidst possible loss to follow-up or data incompleteness.

Sampling Architecture and Stratification

The sampling schema adopted a semi-probabilistic, stratified systemic random sampling design. Historical census data indicated an average monthly surgical admission load of 202 patients for the procedures of interest. To derive a feasible and representative subset, 50% of this load (n = 101) was targeted for inclusion. The surgical department, comprising six distinct operative units, underwent systematic randomization, from which three units were selected using algorithmic random number generation. Patients were consecutively recruited from designated operative days corresponding to these units and were longitudinally monitored over a 30-day postoperative surveillance window.

Eligibility Criteria: Inclusion and Exclusion Paradigms

Inclusion Criteria:

1. Adult postoperative patients (≥18 years) undergoing abdominal or hernia surgery, either admitted in inpatient surgical wards or presenting to the outpatient department (OPD) within 30 days post-procedure.

Exclusion Criteria:

1. Pediatric patients (<18 years).
2. Postoperative patients presenting after 30 days of surgical intervention.
3. Individuals undergoing non-abdominal or non-herniorrhaphy surgeries.
4. Cases involving non-bacterial etiologies, including fungal, viral, anaerobic, or mixed polymicrobial infections unrelated to surgical instrumentation.

Intervention Protocol

No experimental or interventional modality was introduced; the study adhered strictly to an observational, non-interventional framework, thereby nullifying confounding iatrogenic bias.

Definition of Case-Control Paradigm

Given the non-comparative, descriptive construct of this observational study, no explicit case-control bifurcation was employed. All data were analyzed under a single-cohort framework without stratification into matched comparison arms.

Data Collection Instruments and Procedural Workflow

Data acquisition was triangulated through:

1. A Patient Consent Form (informed and voluntary),
2. A Pre-validated Questionnaire probing sociodemographic and clinical determinants,
3. A Case Study Form (CSF) chronicling procedural specifics, environmental exposures, and antimicrobial usage.

Direct, biweekly ward visits were conducted over a continuous four-week period, with follow-up data procured via in-person assessment or telecommunication depending on patient discharge status. Cases manifesting clinical evidence of SSI underwent wound site microbiological sampling through a rigorously sterile in situ technique.

Inclusion and Exclusion Criteria

Included were adult post-operative patients (>18 years) undergoing abdominal or hernia surgeries, followed up for 30 days post-operatively. Patients with non-surgical infections, post-30-day complications, or undergoing non-abdominal procedures were stringently excluded.

Surveillance and Sample Collection

Post-operative patients were followed in situ and telephonically for clinical evidence of SSI. Upon suspicion, wound swabs were aseptically collected using sterile moistened swabs from the deepest viable tissue (avoiding necrotic areas), and cultured on appropriate aerobic media.

Laboratory Protocols

 Antibiotic susceptibility testing followed the CLSI guidelines, with interpretation referencing WHO’s priority pathogen list. Following meticulous lavage of the wound bed using isotonic sodium chloride to dislodge necrotic detritus, residual irrigant is delicately blotted with sterile gauze, subsequent to which contaminated gloves are doffed, aseptic integrity re-established via hand antisepsis, and sterile gloves reapplied. A 0.9% NaCl-moistened culture swab is then firmly rotated for five seconds upon a delineated 1 cm² area of viable, non-necrotic tissue to elicit exudate, deliberately eschewing wound margins, following which the specimen is hermetically secured in a sterile receptacle and the site is re-dressed under strict asepsis.

Statistical Analysis

Data was tabulated using Microsoft Excel, and descriptive plus inferential statistics were executed using SPSS v26. Parameters included frequency distributions, standard deviations, means, and resistance ratios, with categorical comparisons drawn using Chi-square and logistic regression where applicable.

1. Demographic Characteristics
2. Total Participants (n = 101)
3. Gender Distribution: Males (60.4%) exceeded females (39.6%), yielding a Male: Female ratio of 1.52:1.
4. Age Profile:
   46. Mean Age: 46.78 years; Median: 46; SD: ±14.71
   47. Range: 19–85 years (Span = 66 years)

2. SSI Incidence

1. Total SSI Cases Identified: 101
2. Culture Positive SSI: 66 cases (65.3%)
3. Culture Negative SSI: 35 cases (34.7%)
4. Microbiological Spectrum of Isolates

Among the 66 culture-positive patients, polymicrobial growth was observed in 18 cases (27.2%).

Frequency of Isolated Pathogens:

TABLE - Frequency Distribution of Pathogens Isolated from Surgical Site Infections (n = 101)

4. Antimicrobial Resistance Profile

Gram-Negative Resistance (E. coli, Klebsiella, Pseudomonas)

49. Ciprofloxacin Resistance: 50/101 (49.5%)
50. Carbapenem Resistance: Meropenem (53.5%), Imipenem (52.5%)
51. Aminoglycosides: Gentamicin (53.5%), Amikacin (52.5%)
52. Cephalosporins:
    60. Ceftazidime: 60.4% resistance
    61. Cefuroxime: 61.4% resistance
53. Tigecycline: Sensitivity preserved in 1.0% only
54. Colistin Resistance: 47.5%

Gram-Positive Resistance (MRSA, Enterococci)

57. Linezolid: 57.4% resistance
58. Clindamycin: 62.4% resistance
59. Vancomycin: 60.4% resistance
60. Daptomycin: 64.4% resistance

Broad Resistance Overview (Selected Data)

61. Tobramycin: 61.4% resistance
62. Tetracycline: 60.4%
63. Aztreonam: 63.4%
64. Chloramphenicol: 62.4%
65. Penicillin B: 61.4%
66. Piperacillin-tazobactam: 58.4%

Surgical Site Infections (SSIs) persist as an insidious and omnipresent challenge within both resource-rich and resource-constrained healthcare environments, despite progressive incorporations of infection control frameworks and evidence-guided antimicrobial protocols. The persistent nosological footprint of SSIs, as a component of the broader nosocomial infection constellation, is reflective of multifactorial pathophysiological interactions compounded by infrastructural, microbial, and host-derived determinants. Contemporary literature has established that SSIs constitute nearly one-fifth of all healthcare-associated infections (HAIs), with their sequelae contributing to an exponential (2–11 fold) elevation in postoperative morbidity and mortality indices, with approximately 75% of SSI-associated mortalities directly attributable to infectious sequelae themselves [14].

In the current investigation, the institution-specific point prevalence of SSI was adjudicated at 12.02%, derived from the cohort of 101 symptomatically manifest cases among a denominator of 840 surgically treated patients. This prevalence rate, though non-trivial, is positioned intermediately between previously reported rates from Eastern India, such as the 6.3% incidence noted by Banik et al. [15], and the 16.44% delineated by Ghosh et al. [16], suggesting institution-specific variability likely modulated by differential sterility compliance, patient risk stratification, and microbiological ecosystem variability.

The spatial epidemiology of SSIs across the Indian subcontinent further corroborates a heterogeneous distribution; while several multicentric studies from urbanized nodes report prevalence averages clustering around the 20% threshold [17–21], anomalously elevated rates (>20%) have been reported in regional cohorts from Karnataka (2024) [22] and Gujarat (2012) [23], potentially indicating regional disparities in healthcare delivery models and antimicrobial stewardship adherence. Sex distribution within our cohort revealed a male predominance (60.4%), echoing the gendered preponderance observed in prior Indian studies [19–21, 24]. This demographic bias may be reflective of sociocultural, occupational, or health-seeking behavior patterns endemic to the Indian context. The median age of SSI acquisition was 46 years, aligning with data suggesting that increasing chronological age acts as an independent covariate modulating the immune-inflammatory interplay and delaying optimal wound healing kinetics. Among the 101 clinically suspected SSI cases, culture negativity was observed in 35 specimens (34.7%), suggesting potential fastidious organisms, anaerobic pathogens, or prior empirical antibiotic masking. The remaining 66 culture-positive samples yielded an illuminating portrait of the etiological landscape. Notably, 27.2% of these culture-positive cases were polymicrobial, substantiating the polymicrobial nature of SSIs previously implicated in refractory wound healing and protracted antimicrobial courses.

The microbial landscape was conspicuously dominated by Gram-negative bacilli, a pattern recurrently observed in multiple Indian studies [15–18]. Specifically, Escherichia coli emerged as the principal isolate (23.8%), closely followed by Klebsiella spp. (22.8%), and Pseudomonas aeruginosa (11.9%), with Proteus spp. (7.9%) rounding off the significant Gram-negative contributors. The Gram-positive cocci, though numerically inferior, comprised notably virulent and resistant strains including MRSA and Enterococcus faecium, each accounting for 5% of total isolates, while MSSA, Streptococcus spp., and Corynebacterium diphtheroids were marginally represented.

The antibiotic susceptibility profile unveils a somber panorama of escalating antimicrobial resistance. The resistance architecture for Gram-negative bacilli exhibited marked recalcitrance to beta-lactam agents, fluoroquinolones, aminoglycosides, and even carbapenems, with resistance rates for ciprofloxacin, amikacin, and meropenem approximating or exceeding 50%. Specifically, E. coli and Klebsiella spp. demonstrated preserved susceptibility to tigecycline in only 79% and 67% of isolates, respectively, with colistin resistance also emerging alarmingly at 47.5%. These findings resonate disturbingly with global meta-analytical data suggesting the blunting of efficacy even among last-resort agents [22]. Pseudomonas aeruginosa displayed narrow susceptibility profiles, retaining approximately 50% sensitivity to ciprofloxacin, while showcasing pan-resistance to cephalosporins, carbapenems, and aminoglycosides. Among the Gram-positive cohort, both MRSA and E. faecium isolates evinced 60% sensitivity to linezolid and doxycycline, yet were conspicuously resistant to nearly all other first-line agents including ciprofloxacin, levofloxacin, clindamycin, and vancomycin, with daptomycin resistance recorded at an alarming 64.4%. These resistance patterns are congruent with microbiological surveillance data from Karnataka [22], Chhattisgarh [21], and Nepal [24], reinforcing the notion of a transnational surge in multidrug-resistant organisms (MDROs).

The overwhelming resistance documented across both Gram-positive and Gram-negative cohorts compels a paradigm shift in both prophylactic and therapeutic antimicrobial protocols within surgical units. It reinforces the exigency for interdisciplinary interventions, integrating clinical pharmacology, infectious disease modelling, and microbiological diagnostics to formulate locally sensitive and temporally responsive stewardship policies.

Thus, the present study does not merely highlight the pathogenetic burden of SSIs within an Eastern Indian tertiary setting but also functions as an epidemiological bellwether, indicating an impending therapeutic crisis  If resistance mitigation strategies are not expeditiously enacted.

This study unequivocally delineates a pervasive and worrisome landscape of surgical site infections in post-operative abdominal and hernia surgeries within a tertiary-care institution of Eastern India. Despite comprehensive hospital infection control protocols, the prevalence rate of 12.02% remains a glaring indictment of current prophylactic and therapeutic measures.

The microbiological analysis underscored a dominance of Gram-negative bacilli, particularly E. coli and Klebsiella, corroborating prior regional studies. The presence of polymicrobial infections and a high proportion of multidrug-resistant organisms (MDROs)—especially resistance to carbapenems, aminoglycosides, and third-generation cephalosporins—compels an urgent recalibration of both empirical antibiotic strategies and local antimicrobial stewardship policies. Notably, Tigecycline and Colistin, which should be considered last-resort options, are already exhibiting erosion in efficacy, indicating impending therapeutic nihilism in high-risk postoperative cohorts. The resistance noted to frontline agents such as ciprofloxacin and cefuroxime further underscores the collapse of traditional antimicrobial hierarchies.

In summation, this study contributes a critical epidemiological datum for SSI surveillance in Eastern India and necessitates immediate interdisciplinary dialogue among microbiologists, surgeons, and pharmacologists. Establishment of rigorous surveillance, rotation-based antibiotic policies, and early de-escalation protocols shall be the only viable counteroffensives against this growing iatrogenic microbial insurgency.

Study gap- Limited sample size and the antimicrobial susceptibility profile is done using phenotypic methods.

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