Surgical Site Infections (SSIs) represent one of the most common healthcare-associated infections, affecting millions of patients worldwide annually. They are a major source of postoperative morbidity, leading to increased pain, prolonged hospital stays, higher readmission rates, and a substantial economic burden on healthcare systems [1, 2]. The pathogenesis of an SSI is a complex interplay between patient-related factors (host immunity, comorbidities), microbial factors (virulence, inoculum size), and procedure-related factors (duration of surgery, surgical technique, aseptic protocols) [3]. The skin, as the primary barrier to the external environment, plays a pivotal role in this dynamic; its integrity and microbial ecology are fundamental to preventing incisional infections.

The normal human skin is home to a diverse community of commensal microorganisms, collectively known as the skin microbiome. This ecosystem is meticulously balanced and can resist colonization by pathogenic species [4]. However, this delicate balance is disrupted in various dermatological conditions. Inflammatory skin diseases such as psoriasis, atopic dermatitis, and eczema compromise the structural integrity of the epidermis, creating microscopic breaches through which pathogens can invade [5]. Furthermore, the chronic inflammatory state in these conditions alters the local immune response, often creating a microenvironment that is paradoxically more susceptible to infection. The skin affected by these diseases is frequently colonized by higher concentrations of pathogenic bacteria, most notably Staphylococcus aureus, even when there is no overt clinical infection [6, 7].

The impact of these pathophysiological changes on surgical outcomes is a logical, yet under-explored, area of concern. When a surgical incision traverses a region of skin that is already inflamed, broken, or abnormally colonized, the risk of introducing pathogens into the deeper tissues is theoretically and demonstrably elevated. Active skin lesions in the operative field can serve as a direct source of bacterial contamination during surgery. Even in the absence of active lesions, the altered skin barrier and microbiome in patients with chronic dermatoses may predispose them to a higher risk of postoperative infection and impaired healing [8]. Several studies have shown that patients with conditions like psoriasis have a higher overall rate of infections compared to the general population, but data specifically linking dermatological pathology to SSI are less comprehensive [9].

In the context of the Indian subcontinent, and Tamil Nadu specifically, the prevalence of infectious and inflammatory dermatoses is significant [10]. Conditions like chronic eczemas, fungal infections, and autoimmune blistering disorders are frequently encountered in tertiary care centers. Often, patients and sometimes surgeons may overlook these skin conditions, especially if they are considered "minor" or "non-active." This perception can lead to a lack of preoperative optimization. Given the high volume of surgical procedures and the constant need to improve patient outcomes, identifying modifiable risk factors like pre-existing skin disease is of paramount importance. This study was therefore designed to prospectively investigate the role of pre-existing dermatological disorders as predictors for the development of SSI and delayed wound healing in a cohort of patients undergoing elective surgery at a tertiary care hospital in Tamil Nadu.

OBJECTIVE

The primary objective of this study was to determine whether the presence of any pre-existing dermatological disorder in the planned operative field is an independent risk factor for the development of Surgical Site Infection (SSI) within 30 days of surgery. We sought to quantify this risk in a cohort of Indian patients undergoing elective surgical procedures.

A secondary objective was to assess the impact of these dermatological conditions on the dynamics of wound healing, specifically focusing on the rate of delayed wound healing. Furthermore, we aimed to identify specific categories of dermatological disorders (e.g., inflammatory vs. infectious, active vs. inactive) and patient characteristics (e.g., use of topical immunosuppressants, colonization status) that confer the highest risk, which could inform targeted preoperative screening and management protocols.

This prospective, observational cohort study was conducted at a 1200-bed tertiary care teaching hospital in Chennai, Tamil Nadu, India, over a 12-month period from September 2021 to August 2022. The study was initiated after obtaining formal approval from the Institutional Ethics Committee (IEC). A total of 84 patients scheduled for elective general surgical, orthopedic, or obstetric/gynecological procedures were recruited for the study. These patients were divided into two groups: a "Case Cohort" (n=42) consisting of patients with a pre-existing dermatological disorder involving or immediately adjacent to the planned surgical incision site, and a "Control Cohort" (n=42) consisting of age and sex-matched patients without any visible skin pathology in the operative field. Written informed consent was obtained from all participants prior to enrolment in the study. Inclusion Criteria: • Patients aged 18 years or older. • Patients scheduled for an elective surgical procedure with a clean or clean-contaminated wound classification. • For the Case Cohort: Presence of a clinically diagnosed dermatological disorder (e.g., psoriasis, eczema, tinea, chronic dermatitis) that either directly involves or is within 5 cm of the planned incision line. • For the Control Cohort: Absence of any visible dermatological disorder in the operative region. Exclusion Criteria: • Patients undergoing emergency surgery. • Patients with a pre-existing systemic infection or on systemic antibiotic therapy for >72 hours prior to surgery. • Patients with severe immunosuppression (e.g., HIV/AIDS, active malignancy on chemotherapy, organ transplant recipients). • Patients with uncontrolled diabetes mellitus (HbA1c > 9%). • Patients on systemic immunosuppressive therapy (e.g., methotrexate, cyclosporine, biologics) in the 3 months preceding surgery. • Patients undergoing surgery involving a previously irradiated field. • Pregnant patients with dermatological disorders specific to pregnancy (e.g., pruritic urticarial papules and plaques of pregnancy). Data Collection Procedure: Upon enrollment, a detailed history was taken from all patients, and a thorough physical examination was performed. Demographic data, primary diagnosis, comorbidities, and perioperative details (type of procedure, wound class, duration of surgery, American Society of Anesthesiologists (ASA) score) were recorded on a standardized proforma. For patients in the Case Cohort, the specific dermatological diagnosis was confirmed by a consultant dermatologist. The skin condition was classified as "Active" (presence of erythema, scaling, crusting, vesiculation, or weeping) or "Inactive" (post-inflammatory hyperpigmentation or quiescent disease). A swab was taken from the lesion (or from the site of prior lesions for inactive cases) before surgical skin preparation and sent for microbiological culture and sensitivity. Postoperatively, patients were assessed daily during their hospital stay by an investigator blinded to the patient's group assignment. Following discharge, patients were followed up in the outpatient department on postoperative days 7, 14, and 30. The primary outcome, Surgical Site Infection, was defined according to the Centers for Disease Control and Prevention (CDC) criteria [11]. This includes the presence of purulent drainage, pain or tenderness, localized swelling, redness, or heat, or a positive aseptically obtained culture from the incision site. The secondary outcome, Delayed Wound Healing, was defined as the failure of complete epithelialization of the surgical wound by postoperative day 14. Wounds that were dehisced or required secondary closure were also classified as delayed healing. Statistical Data Analysis: Data were entered into a Microsoft Excel spreadsheet and analyzed using SPSS software (version 26.0, IBM Corp., Armonk, NY). Continuous variables are presented as mean ± standard deviation (SD) and were compared using an independent samples t-test. Categorical variables are expressed as frequencies and percentages and were compared using the Chi-square test or Fisher’s exact test where appropriate. A univariate analysis was performed to identify potential risk factors for SSI. Variables with a p-value < 0.20 in univariate analysis were entered into a multivariate logistic regression model to identify independent predictors of Surgical Site Infection. A two-tailed p-value of < 0.05 was considered statistically significant for all analyses.

A total of 84 patients were enrolled in the study, with 42 patients in each cohort. The demographic and baseline clinical characteristics of the two groups were comparable. The mean age was 48.5 ± 12.1 years in the case group and 50.1 ± 11.5 years in the control group (p=0.54). There was no statistically significant difference in gender distribution, ASA scores, or the proportion of patients with controlled diabetes mellitus (Table 1). The most frequently encountered dermatological disorders in the case cohort were chronic eczemas (n=14, 33.3%), psoriasis (n=10, 23.8%), and dermatophytosis (tinea) (n=8, 19.0%). Of these, 26 patients (61.9%) were classified as having "Active" dermatoses at the time of surgery. Preoperative skin swabs from the case group revealed colonization with Staphylococcus aureus in 11 patients (26.2%).

Table 1: Baseline Characteristics of Study Participants

The primary outcome, the incidence of SSI, was significantly higher in the group with pre-existing dermatological disorders. A total of 15 patients (35.7%) in the case cohort developed an SSI, compared to only 5 patients (11.9%) in the control cohort. This difference was statistically significant (p=0.01). Similarly, the secondary outcome of delayed wound healing at day 14 was observed in 19 patients (45.2%) in the case group, which was significantly higher than the 7 patients (16.7%) in the control group (p=0.005) (Table 2). The mean time to complete wound healing was also longer in the case group (16.2 ± 3.5 days) compared to the control group (12.1 ± 2.1 days, p<0.001).

Table 2: Comparison of Primary and Secondary Outcomes

A subgroup analysis within the case cohort revealed that the risk was not uniform across all dermatological conditions. Patients with active inflammatory dermatoses had an SSI rate of 50% (13/26), compared to 12.5% (2/16) in those with inactive disease. The presence of S. aureus colonization was also a strong predictor; 81.8% (9/11) of patients colonized with S. aureus developed an SSI, whereas the SSI rate was only 19.4% (6/31) in non-colonized patients (Table 3). Multivariate logistic regression analysis confirmed that having an active inflammatory dermatosis (OR 4.5; 95% CI 1.6-12.7; p=0.004), S. aureus colonization (OR 3.8; 95% CI 1.2-11.9; p=0.02), and the use of topical corticosteroids in the preoperative period (OR 3.1; 95% CI 1.0-9.3; p=0.04) were independent risk factors for the development of an SSI.

Table 3: Subgroup Analysis of Risk Factors for SSI within the Case Cohort (n=42)

This prospective cohort study provides robust evidence that pre-existing dermatological disorders in the operative field significantly increase the risk of adverse postoperative outcomes, specifically Surgical Site Infections and delayed wound healing. Our findings demonstrate a three-fold increase in SSI risk and a nearly three-fold increase in delayed healing among patients with skin pathology compared to controls. These results underscore the critical importance of recognizing and, where possible, optimizing the skin's condition before any elective surgical intervention. The elevated risk associated with dermatological disorders can be attributed to several interconnected pathophysiological mechanisms. Firstly, the integrity of the epidermal barrier is fundamentally compromised in most skin diseases. In conditions like eczema and psoriasis, the "bricks and mortar" model of the stratum corneum is disrupted, leading to increased transepidermal water loss and creating microscopic portals of entry for pathogens [12]. This breach of the primary physical barrier allows resident or transient skin flora, particularly S. aureus, to access deeper tissues during a surgical incision. Our finding that active inflammatory dermatoses were an independent risk factor (OR 4.5) strongly supports this barrier disruption theory. The chronic inflammation itself is the second major factor. The inflamed skin is a site of intense immune cell activity, with a predominance of T-helper type 2 (Th2) cells in atopic dermatitis and Th17 cells in psoriasis. These cytokines, such as IL-4, IL-13, and IL-17, have been shown to directly impair the expression of antimicrobial peptides (AMPs) like human beta-defensins in keratinocytes, thereby weakening the local innate immune defense against invading microbes [13, 14]. This creates a "double-hit" phenomenon: a broken barrier and a compromised local immune system. A particularly striking result from our study is the powerful association between preoperative colonization with S. aureus and the development of SSI (81.8% infection rate vs 19.4%). This reinforces the well-established role of S. aureus as a dominant pathogen in surgical site infections [15]. It is known that patients with atopic dermatitis and psoriasis have significantly higher rates of S. aureus colonization, not only on lesional but also on non-lesional skin [6]. The high bacterial burden serves as a substantial inoculum that can easily contaminate the surgical wound. Furthermore, the use of topical corticosteroids, identified as an independent risk factor in our analysis, likely compounds these risks. While they reduce inflammation, they also have local immunosuppressive effects, inhibiting fibroblast proliferation and collagen synthesis, which are essential for wound healing, and further dampening the innate immune response [16, 17]. Surgeons must be acutely aware that a patient with chronically inflamed, eczematous skin using topical steroids is in a high-risk category for SSI. The implications of these findings for clinical practice are substantial. The standard preoperative assessment often focuses heavily on systemic issues cardiac function, diabetic control, and coagulation status while the skin may receive only a cursory glance. Our data strongly advocate for a more rigorous, systematic evaluation of the skin at the planned incision site. For patients with visible dermatoses, elective surgery should ideally be postponed until the condition is optimized. This might involve a consultation with a dermatologist, initiation of appropriate therapy (e.g., antibiotics for secondary infection, immunomodulators), and a period of disease remission. The presence of an active inflammatory lesion should be a "red flag." Furthermore, preoperative screening for S. aureus carriage and subsequent decolonization protocols (e.g., intranasal mupirocin and chlorhexidine body washes) have been shown to reduce SSI rates in other high-risk groups like cardiac and orthopedic surgery patients [18, 19]. Extending such protocols to patients with dermatological disorders appears to be a logical and evidence-supported strategy. Our study provides the foundational data that would justify such an interventional trial. The finding that delayed wound healing is also more prevalent in this cohort is not surprising. Wound healing is a complex, coordinated sequence of events, and chronic inflammation is known to disrupt this process, keeping the wound in a prolonged inflammatory phase and preventing progression to proliferation and remodeling [20]. The altered cytokine milieu, impaired local immunity, and the effects of medications like topical steroids all contribute to a slower, more complicated healing trajectory. This prolonged healing time further increases the window of vulnerability for a wound to become secondarily infected, creating a vicious cycle. Delayed healing not only affects patient quality of life but also prolongs the need for wound care resources and follow-up appointments, adding to the overall cost of care [21]. Limitations of the Study This study has several important limitations that must be acknowledged. Firstly, the relatively small sample size (n=84) is a major constraint. While the study was sufficiently powered to detect a large difference in the primary outcome, it limits the generalizability of our findings and reduces the statistical power for subgroup analyses. A larger, multi-center study would be necessary to confirm these results and explore risk factors within specific dermatological disease categories more robustly. Secondly, as an observational study, we cannot fully exclude the impact of unmeasured confounding variables. For example, subtle differences in surgical technique, perioperative glycemic control, or patient adherence to postoperative wound care instructions could have influenced outcomes. Thirdly, the blinding of the outcome assessor, while attempted, may have been compromised in cases where the dermatological condition was visible on follow-up. Finally, the study was conducted in a single tertiary care center in Tamil Nadu, and the patient population and specific spectrum of dermatological diseases encountered may not be representative of other geographic regions or healthcare settings. These limitations highlight the need for further research in this area. Acknowledgement We would like to express our sincere gratitude to all the patients who willingly participated in this study, without whom this research would not have been possible. We are deeply thankful to the Department of Dermatology, Venereology, and Leprosy for their invaluable collaboration in the diagnosis and assessment of patients. Our appreciation extends to the Department of Microbiology for their assistance with the collection and analysis of skin swabs. We also thank the hospital administration and the Institutional Ethics Committee for providing the necessary permissions and support to conduct this research project. This study did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

In conclusion, this prospective cohort study from a tertiary care center in Tamil Nadu has demonstrated that the presence of a pre-existing dermatological disorder at the surgical site is a significant and independent risk factor for both Surgical Site Infection and delayed wound healing. The risk is particularly pronounced in patients with active inflammatory dermatoses, those colonized with Staphylococcus aureus, and those using topical corticosteroids preoperatively. These findings highlight a critical, yet often overlooked, aspect of preoperative patient optimization.

The results of this study compel a paradigm shift in surgical practice. We recommend that a detailed dermatological history and a thorough skin examination be an integral part of the pre-operative assessment for all elective surgeries. Patients identified with active skin disease should be referred for dermatological consultation with the goal of achieving disease remission or control prior to proceeding with surgery. In cases where surgery cannot be deferred, targeted interventions such as S. aureus decolonization, optimization of topical therapy, and meticulous aseptic technique are essential to mitigate the heightened risk. By adopting these strategies, healthcare providers can potentially reduce the significant burden of postoperative complications, leading to improved patient outcomes, shorter hospital stays, and more efficient use of healthcare resources. Future research should focus on interventional trials to assess the efficacy of specific preoperative skin optimization protocols in reducing SSI rates in this high-risk patient population.