Surgical site infection in colorectal surgery

Arshad Ahmed Baba; Afshan Anjum Wani; Asif Mehraj; Nisar Ahmad Chowdri; Fazl Qadir Parray; Rauf A Wani; Mudassir Ahmad Khan

doi:10.4103/IJCS.IJCS_12_18

ORIGINAL ARTICLE

Year : 2019 | Volume : 2 | Issue : 3 | Page : 63-70

Surgical site infection in colorectal surgery

Arshad Ahmed Baba, Afshan Anjum Wani, Asif Mehraj, Nisar Ahmad Chowdri, Fazl Qadir Parray, Rauf A Wani, Mudassir Ahmad Khan
Department of Colorectal Surgery, SKIMS, Srinagar, Jammu and Kashmir, India

Date of Web Publication

22-Sep-2020

Correspondence Address:
Dr. Arshad Ahmed Baba
Department of Colorectal Surgery, SKIMS, Srinagar, Jammu and Kashmir
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/IJCS.IJCS_12_18

Abstract

SSI is a common complication following colorectal surgeries. We present data on the incidence of the same and the factors attributed for its causation at our centre which is a tertiary care centre and a high volume centre for colorectal surgeries. Of the total 538 patients, 316 (58.7%) were males while 222 (41.3%) were females. Mean age of the patients was 47.36±15.57 years, with a minimum age of 18 years and a maximum of 85 years. Elective procedures contributed for 84.01% (452) while 15.98% (86) cases were performed as emergency procedures. Of the total 538 patients 452 patients were electively operated, of which 67 (14.8%) developed SSIs. In emergency procedures 86 patient were operated, of which 31 (36.0%) developed SSI. In our study, total SSI was observed in 67 cases, of which superficial SSI were 46 (68.65%), and deep SSI cases, were11 (16.4%), and organ space SSI cases were 10 (14.9%).

Keywords: Colorectal surgery, complications in colorectal, surgical site infections

How to cite this article:
Baba AA, Wani AA, Mehraj A, Chowdri NA, Parray FQ, Wani RA, Khan MA. Surgical site infection in colorectal surgery. Indian J Colo-Rectal Surg 2019;2:63-70

How to cite this URL:
Baba AA, Wani AA, Mehraj A, Chowdri NA, Parray FQ, Wani RA, Khan MA. Surgical site infection in colorectal surgery. Indian J Colo-Rectal Surg [serial online] 2019 [cited 2023 Mar 29];2:63-70. Available from: https://www.ijcrsonweb.org/text.asp?2019/2/3/63/295851

Background

Surgical site infections (SSIs) have been recognized as the third most common healthcare-associated infections (HAI).^[1],[2] Hospital acquired infections are not only an important cause of morbidity and mortality but also cause severe economic impact throughout the world.^[1]

Colon and rectal surgery (CRS) is consistently associated with higher SSI rates relative to other surgery. CRS SSI rates range from 4% to 45%.^[3],[4],[5] Nearly, all the same risk factors that correlate with any type of SSI are similarly identified in CRS. Frequently identified predictive factors for CRS SSIs are obesity, diabetes, type of procedure, technique (e.g., open vs. laparoscopic) longer operative time, and emergency operations.^[4],[6],[7]

The CDC describes three types of SSIs:^[8]

Superficial incisional SSI – This infection occurs just in the area of the skin where the incision was made
Deep incisional SSI – This infection occurs beneath the incision area in muscle and the tissues surrounding the muscles
Organ or space SSI – This type of infection can be in any area of the body other than skin, muscle, and surrounding tissue that was involved in the surgery. This includes a body organ or a space between organs.

To prevent SSI various techniques starting from considering the aspect of health-care provider, environment of the operating room to the preoperative preparation for the patient, can be performed. The lower rates of SSI in developed countries compared to the developing countries indicate better implementation of infection control practices along with availability of proper surveillance system. The use of antimicrobial prophylaxis might lead to variations in incidence of SSI.

Methods

The main objective of the study was to evaluate the colorectal SSI outcomes at a tertiary care center and high volume center for colorectal surgery.

The objectives may be summarized as follows:

To determine the frequency of SSIs in colorectal surgeries
To compare incidence of SSI in elective and emergency colorectal surgeries
To identify the associated risk factors
To suggest preventive measures (if any) for the prevention of SSI in colorectal surgeries.

Type of study

This was prospective study.

Place of study

The study was conducted in the Department of General and Minimal Invasive Surgery, Colorectal Division, Sheri-i-Kashmir Institute of Medical Science (SKIMS), Srinagar.

Period of study

The study includes all the patients presented to general surgery department with any type of colorectal surgery from July 1, 2013 to June 31, 2015.

Sample size

The sample size was 538 cases.

Inclusion criteria

Study includes all surgical inpatients, undergoing emergency, and elective colorectal surgery (following the ACS NSQIPs defined CPT codes).

Exclusion criteria

Patients with trauma and transplant patients and patients under 18 were excluded from the study.

Study procedure and data collection

During the study, data were collected on a predesigned pro forma for all the patients. The patients were monitored daily for any signs of infection.

Infected cases were identified using CDC, USA definition for SSI. After discharge, patients were followed up at weekly interval to check for any sign of infection. The patients were followed for 30 days to look for SSI. If there were no signs of infection within 30 days of operation, the patient was regarded as having no SSI. The patient who was not able to visit every week was contacted on phone to inquire about their wound condition.

Data analysis

Statistical software SPSS (IBM version 20.0) and Microsoft Excel were used to carry out the statistical analysis of data. Data were analyzed by means of descriptive statistics namely, means, standard deviations, and percentages and presented by Bar Diagrams. For parametric data, Student's independent t-test was employed. Chi-square test or Fisher's exact test, whichever appropriate, was used for nonparametric data. A P < 0.05 was considered statistically significant.

The patient consent was not required in our study as it did not involve any intervention on them or revealing their personal identity in any form.

Results

This study was conducted in the Department of General and Minimal Invasive Surgery, Colorectal Division, SKIMS, Srinagar. The study includes 538 patients who presented to the said department with any type of colorectal surgery from July 1, 2013 to June 31, 2015, and this was a prospective study. Patients from the age groups of above 18 years were included in the study. The following observations were made.

Of the total 538 patients, 316 (58.7%) were male while 222 (41.3%) were female. The mean age of the patients was 47.36 ± 15.57 years, with a minimum age of 18 years and a maximum of 85 years.

Elective procedures contributed for 84.01% (452) whereas 15.98% (86) cases were performed as emergency procedures. Of the total 538 patients, 452 patients were electively operated, of which 67 (14.8%) developed SSIs. In emergency procedures, 86 patients were operated, of which 31 (36.0%) developed SSI.

In our study, the total SSI was observed in 67 cases, of which superficial SSI was 46 (68.65%), and deep SSI cases were 11 (16.4%), and organ space SSI cases were 10 (14.9%) [Figure 1].

Figure 1: Classification of surgical site infections

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The rate of SSI was correlated with various variables and risk factors and compared between elective and emergency procedures. There was no effect of gender on the rate of SSI either in elective or emergency settings. Body mass index >25 was strongly associated with increased SSI rates. History of smoking, hemoglobin (Hb) levels <11, and albumin levels <3.0 were again associated with increased incidence of SSI. Patients receiving perioperative blood transfusion were more prone to develop SSI in both elective and emergency settings. The type of surgical wound had a significant impact on the rate of SSI, with class 3 and 4 wounds having more predilections for SSI as compared to class 1 and 2 wounds. The rectal surgeries as compared to rest of the colonic surgeries showed increased incidence of SSI. The American Society of Anesthesiologists (ASA) score of 3 and 4 was a significant factor for determining greater incidence in SSI as compared to ASA Grade 1 and 2. Operative time was again an important determinant on the rate of SSI, with surgeries lasting for >2 h showing higher incidence of SSI as compared to surgeries lasting for <2 h [Table 1].

Table 1: Comparision of different variables in elective and emergency setting

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Of the 375 open cases, 67 developed SSI (14.8%). Eighty-five cases were operated laparoscopically, of which 7 (8.9%) cases developed SSI, that was statistically significant with P = 0.001. Decrease in SSI was seen in laparoscopy when compare to the open cases [Table 2].

Table 2: Open versus laparoscopy (elective surgeries; n=452)

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The rate of SSI in the cardiovascular disease cases was found to be 32.8% in elective and 48.4% in emergency surgeries as compared to the cases without cardiovascular disease, whereas as in diabetic cases, it was 31.3% in elective and 35.5% in emergency surgeries. Chronic obstructive pulmonary disease (COPD) cases showed SSI rate of 10.1% in elective and 3.3% in emergency surgeries. The SSI rate among the cases with hypothyroidism was 25.4% in elective and 6.5% in emergency surgeries [Table 3].

Table 3: Comorbidities

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In elective surgeries, among 67 cases of SSI, 56 cases were culture positive, whereas in emergency surgeries among 31 cases of SSI, 28 cases were culture positive. The growth pattern of microorganisms is presented in [Table 4].

Table 4: Microbiome of operated patients

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Discussion

SSIs are one of the most common forms of nosocomial infections that can complicate the surgical procedure. Postoperative wound infection still remains one of the most important causes of morbidity and is the most common nosocomial infection in surgically treated patients. Surveillance for SSI is an essential part in control and prevention of SSI.

The rate of SSI varies greatly worldwide and from hospital to hospital. The rate of SSI after elective colorectal surgery range from 4% to 45%.^{[3],[4],[5],[9]} The overall incidence of SSI in the present study was 18.2%.

Of the total 538 patients, 452 patients were electively operated, of which 67 (14.8%) developed SSIs as compared with various other studies, in which SSI varies from 15% to 21%.^{[10],[11],[12]} In emergency procedures, 86 patients were operated, of which 31 (36.0%) developed SSI. Emergency surgical procedures carry a more risk for SSI as compared to elective procedures, varying from 30% to 60%.^{[13],[14],[15]}

Infection rate was 13.9% in clean-contaminated wounds and 38% in contaminated wounds. Thus, there was clear correlation between the wound infection rate and the contamination of the wound which is in accordance with other studies.^[11],[16]

Risk factors for superficial SSI and deep/organ-space SSI vary in terms of magnitude and significance, suggesting that these SSI types are somewhat different disease processes. In our study, total SSI was seen in 67 cases, of which superficial SSIs developed in 46 (68.65%) cases, deep SSI developed in 11 (16.4%) and organ-space SSI developed in 10 (14.9%) cases. There was no significant differences between these three groups in relation with the infection site.

The rate of SSI increases with the increase in age. In the current study, a higher proportion of SSI was found among the subjects with mean age 50.4 ± 16.16 years with P = 0.023, and in terms of mean age, our study was comparable to other studies.^{[17],[18],[19]}

Smith et al. prospectively assessed the wound infection rate in 176 patients following colorectal resection. Using a multivariate logistic regression analysis, BMI ≥25 was found to be associated with increased rates of SSIs compared to those with a BMI of <25, overweight patients (BMI 25–29.9) had an odds ratio (OR) of 2.5 while obese patients (BMI >30) had an OR of 3.0 of developing a SSI.^[20] A similar result was seen in a multicenter prospective trial of 534 patients undergoing colorectal surgery. Data were collected on 16 variables which may contribute to SSIs and following a multivariate regression analysis obesity remained predictive of SSI with an OR of 2.93.^[21] In our study, SSI was noted more in patients who were overweight or obese (BMI ≥25) than in patients who were having BMI in normal range (BMI <25).

Comorbid conditions such as diabetes, COPD, cardiovascular disease, and hypothyroidism were the significant risk factors for SSI. Diabetes remained a significant predictor of SSI. 31.3% of SSI following colorectal resections were seen in patients with diabetes, (P < 0.001). This result was in concordance with the results of McConnel et al. 2008 who reported 29.7% of SSI following colorectal surgery in patients with diabetes.^[22] In our study, comorbid conditions such as cardiovascular disease 22 (10.4%) and COPD 7 (10.4%) have independently increased the risk of SSI in elective colorectal surgery as compared to patients which were having no SSI and these both results were statistically significant with P value of 0.022 and 0.021, respectively. Other studies were also supporting our results such as those of Sergeant et al. 2013.^[23] The association of hypothyroidism with SSI was statistically insignificant in our study (P = 0.152).

In our study, SSI was also more prevalent in patients having hypoalbuminemia <3.0 g/dl and low Hb <11 g/dl. There is a high incidence of preoperative and postoperative anemia in patients undergoing major noncardiac surgery, with a coincident increase in blood utilization. Preoperative anemia is associated with increased postoperative complications and mortality.^[24] Hypoalbuminemia is an independent risk factor for the development of SSI following gastrointestinal surgery and is associated with deeper SSI and prolonged inpatient stay.^[25] The only risk factor shared by all three site-specific SSIs was intra- or post-operative blood transfusion. In fact, in our study, this risk factor was also the most important factor for the development of SSI. Allogeneic blood transfusion induces immunosuppression and predisposes to postoperative infection.^{[26],[27],[28]} An increased incidence of postoperative infection was observed in recipients of allogeneic transfusions in observational studies.^{[25],[26],[29],[30],[31]} Allogeneic leukocytes have a critical role in the induction of transfusion-induced immunosuppression.^[26],[32]

Of 352 patients, who received mechanical bowel preparation, 55 (15.62%) patients had SSI. Of 100 patients, who received no bowel preparation, 12 (12%) had SSI. The difference was not statistically significant (P = 0.368).

A meta-analysis in which 9 randomized controlled trials (RCTs) was analyzed to evaluate for primary outcome of anastomotic leakage and secondary outcomes of mortality and wound infection. In total, 791 patients received Mechanical Bowel Prepration and 803 had no preparation. There were 6.2% of the patients having MBP who had anastomotic leak, compared to 3.2% of the unprepared patients (OR 2.03, 95% confidence interval [CI] 1.28–3.26), favoring no preparation. SSI was observed in 7.4% of the prepared patients and 5.4% of the unprepared patients (OR 1.45, 95% CI 0.97–2.18).^[33] Another meta-analysis included 14 RCTs with 2452 patients in the MBP group and 2407 in the unprepared group. There was no statistically significant difference observed in the analysis of the primary outcome, anastomotic leakage (4.02% in the MBP group vs. 3.44% in the unprepared group, OR 1.12, 95% CI 0.82–1.53). However, the analysis of secondary outcomes demonstrated a difference in “all SSI” favouring no MBP (15.7% after MBP vs. 14.58% unprepared, OR 1.4, 95% CI 1.05–1.87).^[34] Another analysis was an updated version of an earlier Cochrane review, performed by Guenga and colleagues included analysis of 13 RCTs, with 2390 patients allocated to MBP and 2387 to no preparation. The primary outcome measured was anastomotic leakage; secondary measures included wound infection and overall SSIs. Overall anastomotic leakage was 4.2% in the MBP group versus 3.4% in the unprepared group (OR 1.26, 95% CI 0.941–1.69). There was no difference in the rate of wound infection (9.6% in the MBP group vs. 8.3% in the unprepared group, OR 1.19, 95% CI 0.98–1.45).^[35],[36]

Smoking is an independent risk factor for SSI.^[37] In our study, of 452 patients of elective colorectal surgery group 196 patients were smokers, of which 37 patients developed SSI. In nonsmokers group which were a total of 256 patients of which 30 developed SSI which is statistically significant with P = 0.034.

In our study, among 439 patients with the ASA score of ≤2, 62 (14.1%) patients had SSI. Of 13 patients with ASA >2, 5 (38.5%) patients had SSI. As the ASA score increases, risk of SSI also increases. The difference is statistically significant (P = 0.015). McConnel et al.^[22] reported that patients with ASA score >2 have a higher risk of SSI. Hübner et al.^[17] reported in their study that 27/247 (10.9%) patients with ASA score 1 had SSI, 227/1294 (17.5%) patients with ASA score of 2 had SSI, 147/707 (20.8%) patients with ASA score of 3 had SSI, 27/137 (19.7%) patients with ASA score of 4 had SSI and 0/8 (0%) patient with ASA score of 5 had SSI.

In our study, with increasing operating time SSI rate also increased. Patients with a mean operating time of 2.49 ± 1.27 had more SSI than patients with mean operating time 2.15 ± 1.25. The present data indicated that the operating time of >3 h is risk factor for SSI. Increasing the length of procedure theoretically increases the susceptibility of the wound by increasing bacterial exposure and the extent of tissue trauma (more extensive surgical procedure) and decreasing the tissue level of the antibiotic.^[38] Perioperative prophylactic abtibiotic reduces the wound sepsis rate when combined with oral antibiotics and mechanical bowel preparation in patients undergoing resection of colon and rectum.^[39] This finding supports the notion that the administration of an additional dose of antibiotic in lengthy procedures (e.g., ≥3 h) might be effective in reducing the overall SSI rate. The difference was statistically significant with a P = 0.002. It was also consistent with findings of Hagihara et al and Kaiser et al. who showed that longer operative time (3.3 ± 1.6 vs. 2.7 ± 1.2; P < 0.05) more likely caused SSI than less operating time.^[12],[40]

In the clinical practice, the left colon resections are considered to be more frequently associated with urgent setting and contaminated intra-abdominal conditions compared to right colon surgery. Furthermore, in the left colon resections and in rectal resections, it is expected to have a greater bacterial contamination because of the increasing bacterial density from ileocecal valve to the anal verge.^[41] In our study, the SSI rate in elective colorectal resection was 14.8% while SSI rate in colon and rectal surgeries was 9.23% and 17.08%, respectively; this was statistically significant with P = 0.034. Rectal surgery differs from colon surgery due to greater bacterial contamination, more frequent need for ostomies, longer operations, and possible neoadjuvant treatments in oncological patients.^[5],[42]

In our study, a total of 367 open cases, 60 developed SSI (16.3%) and 85 cases were operated laparoscopically, of which 7 (8.2%) cases developed SSI (P = 0.001). A meta-analysis including several larger RCTs (COlon Carcinoma Laparoscopic or Open Resection and conventional vs. laparoscopic-assisted surgery in colorectal cancer trials) found a decreased rate of wound complications (infection and dehiscence) in favor of the laparoscopic group when compared with the open group (4.7% vs. 7.3%, P = 0.01).^[43]

Therefore, it can be concluded that laparoscopic surgery does not increase the risk of SSI and may well reduce the risk. So, when considering measures to reduce SSI, laparoscopic procedures should be attempted when possible to minimize SSI.

During the study, a total of 86 patients who underwent emergency colorectal resections were enrolled in the study. SSI developed in 31 (36.04%) patients, the high rates of infection in emergency surgeries can be attributed to inadequate preoperative preparation, the underlying condition which predisposed to emergency surgery and more frequency of contaminated or dirty wounds. Different studies from different places have shown SSI rate to vary from 4% to 45%.^{[4],[5],[13],[44]}

Among 67 cases of SSI, of which 56 cases were culture positive. The bacteria isolated were Staphylococcus aureus 25/56 (44.78%), Escherichia ^{More Details} coli 15/56 (26.78%), Enterococcus faecalis 08/56 (14.28%), Klebsiella 3/56 (5.35%), Pseudomonas 3/56 (5.35%), and coagulase-negative staphylococci 2 (3.57%). This is comparable to study conducted by Sexana et al.^[23] In his study, isolated causative organism from different cultures were S. aureus (14/37, 37.83%), E. coli (9/37, 24.32%), Klebsiella sp. (4/37, 10.81%), coagulase-negative staphylococci (4/37, 10.81%), Pseudomonas aeruginosa (2/37, 5.40%), Proteus mirabilis (1/37, 2.7%), and others (3/37, 8.10%).

Among 31 cases of SSI, of which 28 (90.32%) cases were culture positive. The bacteria isolated in cultures obtained from surgical sites in emergency colorectal surgeries were S. aureus 11/28 (39.28%), E. faecalis 7/28 (25%), E. coli 6/28 (21.42%), Klebsiella pneumonia 2/28 (7.14%), Pseudomonas 1/28 (3.75%), and Acinetobacter baumannii 1/28 (3.75%). Some SSIs were associated with multiple organisms. This is comparable to study conducted by Degrate et al. where majority of SSIs (n = 37, 92.5% among all SSIs) were detected before hospital discharge. Pathogens identified from the cultures were coliforms, Staphylococci, anaerobes, and Pseudomonas, without a significant difference between the three groups. Multi-resistant bacteria such as MRSA, extended spectrum beta-lactamases-producing E. coli and Enterococcus faecium were identified in 11%, 12%, and 22% of the cultures, respectively.^[16]

Conclusion

From our work, we concluded that:

SSI continues to be a major event following colorectal surgery in both emergency and elective settings, with an overall incidence of SSI being 18.2%, with 12.4% and 36.0% incidence after elective and emergency procedures, respectively
The incidence of SSI increases with the age of patients
Most of the cases of SSI are of the superficial type followed by deep and organ-space SSI
Smoking, obesity, diabetes, cardiovascular diseases, COPD, hypoalbuminemia, anemia, perioperative blood transfusions, chemoradiation, longer operative time, and higher ASA scores, are all associated with higher incidence of SSI in colorectal surgeries
The mechanical bowel preparation does not prevent the incidence of SSI in colorectal surgeries
The administration of an additional dose of antibiotic in lengthy procedures (e.g., ≥3 h) was effective in reducing the overall SSI rate
Laparoscopy is associated with decreased rate of SSI when compared with the open procedures
We recommend proper preoperative optimization of patients with various comorbidities to prevent SSI
Blood sugar should be under optimal level in the perioperative period
Patients should be encouraged to lose weight before elective procedures
Patients should be counseled to stop smoking before surgery
Patients nutrition in the perioperative period should be tailored as per caloric requirements, with additional protein intake to cope up with the stress of surgery
As surgeons, we should try to minimize the operative time, without wasting time on unnecessary steps and checking all the instruments and gadgets well before starting the operation.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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