Introduction
A surgical site infection is an infection that occurs after surgery in the part of the body where the surgery took place. Surgical site infections can sometimes be superficial infections involving the skin only. Other surgical site infections are more serious and can involve tissues under the skin, organs, or implanted material1 It is also defined as an infection that occurs within 30 days after the operation and involves the skin and subcutaneous tissue of the incision (superficial incisional) and/or the deep soft tissue (for example, fascia, muscle) of the incision (deep incisional) and/or any part of the anatomy (for example, organs and spaces) other than the incision that was opened or manipulated during an operation (organ/space).2
Patients undergoing clean–contaminated, contaminated, and dirty surgical procedures, have a 30-day SSI incidence ranging from 9·4% in high-income countries to 23·2% in low-income countries.3 Incidence of deep tissue and organ space SSIs are less frequent than superficial SSIs.4 SSI prevention is the highest priority worldwide.5 SSIs can be avoided or minimized by the successful implementation of clinical practice guidelines using a multimodal improvement strategy.6 In Faridpur, data about SSIs are still scarce and the true incidence, risk factors and microbiological involvement among the emergency abdominal cases are unknown.
No research has been done to determine the incidence of SSI among abdominal emergency postoperative patients. This study used standardized documentation to provide data of the incidence, risk factors and microbiological pattern associated with SSI among patients who underwent emergency abdominal operations in BSMMCH Surgery Unit - 2 and would be used to modify the risk factors and to establish the sensitivity patterns of organisms to commonly available antibiotics.
Materials and Methods
Study site
The study was conducted in surgery department, unit – 2 of Bangabandhu Sheikh Mujib Medical College Hospital, Faridpur, Bangladesh, a 500-bed capacity government hospital.
Study design and duration
It is a prospective study in which the participants who underwent emergency abdominal surgical operations were followed up for a maximum period of 30 days postoperatively between January 2020 and March 2021.
Study population
Study population was all patients of acute abdomen admitted through emergency under surgery unit-2 of Bangabandhu Sheikh Mujib Medical College Hospital who underwent laparotomy and those who had previous emergency laparotomy at BSMMCH for acute abdomen and were readmitted with wound sepsis within 30 days after operation.
Sample size
The sample size was calculated using open epi software (The Fleiss formula by John Wiley & Sons, 1981). Total sample size for this study was 112 patients.
Study procedures
Following resuscitation and stabilization, admitted patients who met the inclusion criteria were recruited into the study. Written consent to participate in the study was then obtained and a full history and physical examination done. Patient’s data was collected using a pretested interviewer administered semi structured questionnaire.
Variables studied
Dependent variable: Abdominal surgical site infection (SSI).
Independent variables: Age, sex, BMI, ASA class, anemia, DM, cancer, smoking, wound class, surgeon category, type and duration of surgery & use of drain.
Laboratory procedures
The patients who developed SSI, exudates from their wounds were collected using sterile swabs which were transported at room temperatures to the laboratory within 30 minutes of collection. Conventional identification of bacteria was done by Gram staining followed by bacterial identification and antibiotic-susceptibility testing. Culture was done in chocolate agar or MacConkey agar medium. Plates were incubated at 37°C for 12–24 h in an aerobic atmosphere. After incubation for 48–72 h plates were examined for growth and biochemical tests were done to identify the genus and species of bacteria. After 24 h of observation, diagnosis of infection was made. Susceptibility testing was done by the disk diffusion or Kirby-Bauer method.
Statistical analysis
The analysis is done using IBM SPSS version 28.0.0.0. Multiple logistic regression of the independent variables has been done where the development of SSI (17 cases) was considered as dependent variable. Confidence interval was kept at 95 as% and sociated odds ratio (OR) was presented. Statistical significance was considered at p value <= 0.05.
Ethical Approval
The study was approved by the department of surgery, Faculty Research Committee and the Institutional Review Committee of Bangabandhu Sheikh Mujib Medical College Hospital. All participants were provided with a written informed consent.
Results
Patient information
Total 112 patients (85 male and 27 female) were recruited and among them 17 patients (11 male & 6 female) had developed SSI.
Table 1
Patient information
|
Characteristic |
|
SSIs |
|
|
|
No |
Yes |
|
|
Sex |
Female |
21 |
6 (35.3%) |
|
Male |
74 |
11(64.7%) |
|
|
Total |
95 |
17 |
|
|
Age group |
13-35 |
59 |
5 (29.4%) |
|
36-75 |
36 |
12 (70.6%) |
|
Table 2
SSI study patients (N = 17)
Table 3
N: 112 Independent sample t test
Table 4
Bivariate analysis of riskfactors for development of SSIs
Table 5
Multiple logistic regression analysis
Table 6
N: 17: Fisher’s exact test
Incidence of SSI
The overall incidence of surgical site infection was 15.2% (17/112). The SSI incidence was highest in the age group of 36 to 75 years (70.6%). The mean patient age was 36.84 years ± 17.97 (13–75) years, among 85 males, 11 (64.7%) had SSI and among 27 females, 6 (35.3%) had SSI. All of the 17 patients had developed SSI between 2nd and 7th post-operative days. Superficial SSI accounted for 41.2% (7 cases), deep and organ space SSI accounted for 29.4% (5 cases) each.
Etiology of SSIs
Three (3) organisms were responsible for causation of SSIs among this study. These are E. coli (14 cases) 82.4%, Klebsiella pneumoniae (2 cases) 11.8% and Staphylococcus aureus (1 case) 5.8%.
Risk factors associated with SSI
At bivariate logistic regression and independent sample t test age (p = 0.027), BMI (p = 0.034), operative duration (p = 0.001), postoperative oxygen inhalation (p = 0.056) and wound class (p = 0.017) were associated with SSIs. Underweight participants (BMI <18.5) had most SSI (8/17) 47.1%. Majority of the SSI occurred in appendectomy related cases (7/17) 41.18% and laparotomy for traumatic small or large bowel perforation (3/17) 17.6%. Patients undergoing operations for duodenal ulcer perforation had less SSI than any other single procedure (1 out of 16 cases). Three cases had history of previous abdominal surgery and 2 (66.7%) of them developed SSI. Surgery performed within 12 - 24 hours of admission (urgent operations) had most SSI 58.8% (10/17). Trainee surgeon performing alone had more SSI (9/17) 52.9%. Gender, comorbidities, smoking history, type of surgery, ASA class and use of drain were not associated with SSI (Table 3, Table 4).
The final model was composed of only wound class (p = 0.050) and duration of surgery (p = 0.013).
Sensitivity patterns of the causative organisms
Antibiotics that had maximum sensitivity patterns: amikacin (100%), levofloxacin (93.2%), moxifloxacin (92.3%), azithromycin (81.3%), nitrofurantoin (78.6%), gentamicin (68.8%). Antibiotics that had high resistance: Cefuroxime (100%), ceftriaxone (100%), ceftazidime (83.4%) and ciprofloxacin (47.1%). E. coli had highest resistance for Ceftriaxone, cefuroxime and ceftazidime, and had highest sensitivity for amikacin, azithromycin, levofloxacin, moxifloxacin, nitrofurantoin and gentamicin. Klebsiella had highest resistance for ceftriaxone, cefuroxime, ciprofloxacin, azithromycin and doxycycline, and had highest sensitivity for amikacin, gentamicin, and levofloxacin.
S Aureus had highest resistance for cefuroxime, and highest sensitivity for amikacin.
Discussion
Despite advances in sterilization methods, barriers, surgical technique, and availability of antimicrobial prophylaxis, SSIs remain a substantial cause of morbidity, prolonged hospitalization, unplanned readmissions and death all over the world.7 Incidence of SSI differs widely from one hospital to another and from one geographic location to another.8 Around 157,500 SSI cases (3.03%) occur in USA per year.9 SSI rates assessed in a Canadian hospital over a period of 10 years showed a rate of only 4.7%.10 SSI rates of 6.09% to 38.7% were observed in various Indian studies.11 In China, the incidence of SSI in various hospitals varies from 13.0% to 18.0%.12 In most studies in Africa the incidence of SSI was high, at around 16.4%.13 The prevalence rate of SSI was 5.13% to 14.13% in two different studies conducted in Bangladesh.14, 15 In our study the overall prevalence of SSI was 15.2%. The incidence rate variations observed between other literature and our study may be related to the different surveillance systems, post-discharge surveillance and possible underreporting of SSI.16 Advances in infection control like use of positive pressure, exchanges of filtered air per hour, air-conditioning systems with HEPA filters, etc. in theaters to reduce bacterial loads are still lacking in our country and this might contribute to the high incidence of SSI. The high standards of health care which were maintained in the developed countries made the difference in the rates of infection observed in developing countries.16 SSI increases the cost of hospitalization and also led to development of antimicrobial resistance.11
The risk factors for SSI identified were: CDC wound class and duration of surgery. Duration of surgery has a statistically significant association with SSI. In this study, when duration of surgery exceeds three hours, it increase the chance of SSI development (p<0.001). This may be due to a greater exposure of the incision site to pathogens and/or a greater chance of breach of the aseptic technique.16 CDC wound class was also statistically associated with SSI. Surgeries that are clean-contaminated, contaminated and dirty/infected showed an increase chance of developing SSI when compared to clean wounds.
Taking the patient factors into consideration, SSI incidence was most among patients of the age between 36 to 75 years (70.6%), whereas the lowest infection rate was in the age group of 13–35 years (29.4%) in our study. Various studies have reported that with increasing age, the incidence of SSI increases because of impairing immunity.11 The ASA index for the patient’s clinical status before surgery is a recognized risk factor for SSI16 but in our series most of the patients belong to ASA class 1(71.4%), so this became insignificant. Microbiological profile found out E. coli as the main organism responsible for the development of SSI and identified in 82.4% of the cases. Identification of risk factors allows health care professionals to take actions that reduce complications resulting from infections and minimize SSI rates.
To overcome the high infection rate in developing countries, proper surveillance system is required for the use of antibiotics along with the implementation of infection control practices. To reduce the number of airborne particles in the operating theatre simple measures like limiting the number of personnel in the operating theatre with their restricted movements will decrease the dispersion of bacteria.17 Approximately half of SSIs can be prevented using evidence-based strategies.18 The most recent CDC ‘Guideline for the Prevention of Surgical Site Infection’ was published in 2017.18 Prevention of SSI requires a multidisciplinary approach and also include personnel who are responsible for the design, layout and functioning of operating theatres.17
Conclusion
The incidence of SSI in this tertiary hospital is very high (15.2%). The risk factors related with SSI were: CDC wound class (clean- contaminated, contaminated or dirty/infected) and longer duration of surgery. Pus cultures found E. Coli as the predominant organism. Amikacin, levofloxacin and moxifloxacin are very potent antibiotics against organisms that cause SSI in our hospital. CDC guidelines for the prevention of surgical site infection should be followed strictly to decrease the incidence of SSI in our hospital.
Authors' Contributions
Dr. Saiful Islam Khan conceived and designed the research, was the principal investigator, and developed the manuscript as well as its review before submission. Dr. Shifa Khan collected the data. Dr. Muhammad Mofazzal Hossain and Dr. Iqbal Hossain Talukder contributed to the review of the manuscript. Dr. Mohammad Ali performed the data analysis. Dr. Swapan Kumar Biswas supervised the research.
