Surgical site infection following abdominal cancer surgery: a retrospective study in a tertiary care cancer hospital

Background : Surgical site infections (SSIs) are significant complications following abdominal cancer surgery, resulting in patient discomfort, prolonged hospitalization, and increased healthcare costs. Despite efforts to mitigate their occurrence, SSIs remain a challenge in healthcare settings, particularly in low-and middle-income countries . Materials and Methods : This retrospective cross-sectional study aimed to determine the incidence, risk factors, microbiological patterns, and impact of SSIs in patients undergoing open abdominal cancer surgery at a tertiary cancer hospital in Nepal. Results: A total of 206 patients were included in the study, with an SSI incidence of 35.4%. Superficial SSIs accounted for 87.7% of cases, while 12.2% were deep or organ/space infections. The study explored various risk factors, including patient demographics, wound classification, surgical type, and preoperative conditions, and although certain factors showed associations, none reached statistical significance. Notably, longer surgical duration was linked to a higher risk of SSIs. Patients with SSIs experienced significantly longer hospital stays compared to those without SSIs. The predominant pathogens isolated were Escherichia coli, Staphylococcus aureus, and Citrobacter freundii, many of which displayed multidrug resistance. Conclusions: These findings highlight the need for tailored prevention strategies, prudent antibiotic use, and enhanced infection control measures in this high-risk population undergoing abdominal cancer surgery.


Introduction
7][8] Long-term effects of SSI on cancer patients have been linked to have worse outcomes, including shorter disease-free and overall survival. 9,10atients with SSI often experience a longer recovery period, which might cause the delivery of adjuvant therapy to be delayed or skipped altogether, leading to inadequate treatment. 11Several previous studies have identified cancer as an important risk factor for SSI. 12,13However, the incidence, risk factors, and implications of SSI in this highrisk population are unknown.The aims of this study were to describe the incidence and risk factors associated with SSI in patients undergoing abdominal surgery, to study the microbiological pattern of SSI, and to study the effect of SSI on postoperative length of stay.

Study design
A retrospective cross-sectional study was conducted to investigate SSI rate in patients undergoing abdominal cancer surgery at Department of surgical oncology (Thoracic Unit), BP Koirala Memorial Cancer Hospital, Bharatpur, Nepal between February 2022 to February 2023.All patients who underwent open abdominal cancer surgery or surgery involving opening of the peritoneum were included in the study.Patients who underwent laparoscopic surgery or non-cancer were excluded from the study.Ethical clearance was provided by Institutional Review Committee of BP Koirala Memorial Cancer Hospital and informed consent was waived off being retrospective study.

Data collection
Data was collected from prospectively maintained database and hospital records.Medical records of patients who underwent abdominal cancer surgery were reviewed to identify cases of surgical site infection.Demographic information, preoperative and postoperative details were collected.Surgical cases were classified according to the degree of contamination at the time of surgery into clean, clean-contaminated, contaminated, and dirty using the CDC wound class definitions. 1 Based on the depth of infection, these SSIs were subsequently categorized into superficial (affecting the skin and subcutaneous tissue), deep (involving muscle and fascia), and organ space infections.

Statistical analysis
Data entry and analysis was done in Statistical software Package for Social Sciences (SPSS version 23).Descriptive statistics were used to summarize patient characteristics, infection rates, and outcomes.Chi square (χ2) and Fisher's exact tests were used to observe the association.P-value <0.05 was considered statistically significant.Independent sample T test was used to compare duration of surgery and hospital stay.Bivariate analysis was employed to compare risk factors for SSIs.

Results
In total, 206 patients were enrolled in the study, 122 females (59.2%) and 84 males (40.8%) with a mean age of 55 years.Thirtyeight patients were smokers and 43 patients had some sort of comorbidities.Eighty-five patients (41.3%) patients received preoperative chemotherapy.
Age distribution, wound class and type of SSI have been shown in tables 1-3.§ Independent sample T test SSI persists despite the measures and hygienic approach used to reduce its incidence and it is the most common postoperative complication.Because of their limited resources, impoverished populations, and high levels of antibiotic resistance, lowincome countries may be particularly affected by this situation. 15The incidence of SSI in this study was 35.4% which is higher than the previous studies.In the study conducted in Nepal by Giri et al had a SSI rate of 23% in abdominal surgery which is a bit lower than our study. 168][19] The incidence of SSI in abdominal surgeries is relatively higher than other surgeries. 7,15,20,21he outcome might have been worsened by the combination of abdominal surgery and cancer surgery.Cancer is an independent risk factor for SSI and it also has intraoperative risk factors like prolonged duration of surgery, higher blood loss, intraoperative transfusion etc. which may contribute to increased rate of SSI. 12,13st of the wound was clean contaminated and the rate of SSI increased as the wound class increased from clean to dirty wound from 31% to 66%.The infection rate among different wound classes did not show significant differences (p = 0.341).Similar to this study, previous studies have demonstrated that the risk of SSI considerably rises with contamination level. 16,17,22arious risk factors were assessed for their association with surgical site infections.Smoking, ASA grade, diabetes, comorbidities, hemoglobin levels, white blood cell count, and albumin levels were evaluated.However, statistical analysis did not show significant associations between these risk factors and the occurrence of SSIs.This may have been due to the sample size and the specific case mix at our institution.Patients who had received preoperative chemotherapy had lesser SSI, which may be due to response of the tumor and faster and safer surgery.The longer surgical duration was associated with increased SSI risk (p = 0.013) in this study.4][25] Although it is unclear exactly how prolonged operating times increase the prevalence of SSIs, several studies provide logical explanations.Open incisions are exposed to the environment for a longer period of time during longer operations, increasing the chance of bacterial contamination.Longer operating times put incisions at risk for tissue desiccation, which may also increase the likelihood of contamination. 26,27As the duration of surgery prolongs, the tissue concentration of antibiotics decreases if not readministered timely.Longer operative times may also mean increased surgical team fatigue resulting in more technical errors and break in aseptic techniques.Furthermore, higher blood loss from longer operations frequently causes tissue hypoxia and need for blood transfusion which is also associated with increased SSI.Patients who developed SSIs experienced a significantly longer hospital stay compared to those without SSIs (21.8 days vs. 15.7 days, p < 0.001).The correlation between SSI development and longer hospital stays is well-established across many studies. 20,28,29SIs not only lead to increased healthcare costs but also prolong the recovery process and negatively impact patient satisfaction.Even though we did not assess the economic effects of SSI in our study, it is likely that prolonged hospital stays due to SSI results in greater patient care expenses.Escherichia coli was the most frequently isolated bacteria in our study, which was consistent with previous studies. 17,20,24Most of the isolated bacteria were multidrug resistant to commonly prescribed antibiotics which is alarming and judicious use of proper antibiotics is required to fight against antimicrobial resistance.This emphasizes the importance of studying the local sensitivity patterns of bacteria isolated from SSIs in order to guarantee their appropriate treatment.Further consideration regarding selection of proper prophylactic antibiotics will be required.In this study, the majority of pus cultures showed no growth (41%).This might be due to infection by anaerobic bacteria or some fastidious bacteria for which culture facilities are not available at our institution.Also, inappropriate transport or delayed processing of samples may be contributory.This study had several limitations.It was a retrospective analysis with a relatively small sample size.The study cohort was restricted to abdominal cancer surgery only.Data regarding the method and timing of hair removal at a surgical site, glucose management, hypothermia, duration of preoperative hospital stay, blood transfusions, timing of chemotherapy and prophylactic antibiotics were not included.

Conclusion
This retrospective study sheds light on the incidence and risk factors associated with SSIs in a cohort of patients undergoing open abdominal cancer surgery.While the overall SSI rate of 35.4% is concerning, further investigation is warranted to identify effective interventions for reducing this burden.The results emphasize the importance of vigilant infection control practices, judicious antibiotic use, and meticulous surgical techniques to minimize the risk of SSIs.The correlation between longer surgical duration and increased SSI risk emphasizes the necessity of efficient operating protocols to mitigate prolonged exposure of surgical sites.Additionally, the identification of multidrug-resistant pathogens highlights the urgency of implementing antimicrobial stewardship programs and tailoring prophylactic antibiotic regimens to local susceptibility patterns.Addressing these challenges is crucial to enhance patient outcomes, optimize healthcare resources, and alleviate the burden of SSIs on patients and healthcare systems alike.Further research involving larger sample sizes and comprehensive data collection is warranted to develop targeted strategies for preventing SSIs in this high-risk population.

Table 3 :
Surgical site infection

Table 4 :
Type of Surgery

Table 5 :
Risk Factors