Department of Pharmacy Practice, EGS Pillay College of Pharmacy, Nagapattinam, Tamil Nadu 611002
Surgical Site Infections (SSIs) are among the most frequent postoperative complications, especially in low-resource settings, leading to delayed recovery, prolonged hospitalization, and increased healthcare costs. This prospective observational study aimed to evaluate the incidence, microbial spectrum, risk factors, and antibiotic susceptibility patterns of SSIs among general surgery patients in a tertiary care hospital in South India. The study was conducted over a six-month period (April to September 2024) in the Department of General Surgery, Government Medical College Hospital, Nagapattinam. A total of 150 postoperative patients aged 18 to 65 years were included. Clinical data were recorded, and wound swab samples from suspected SSI cases were collected and analyzed using standard microbiological methods. Antimicrobial susceptibility testing was performed in accordance with CLSI guidelines. Out of 150 patients, 70 developed SSIs, resulting in an incidence rate of 46.6%. Males were more commonly affected. The most frequently isolated pathogens included Escherichia coli, Staphylococcus aureus, and Klebsiella pneumoniae. Gram-negative isolates exhibited high resistance to third-generation cephalosporins, whereas meropenem and piperacillin-tazobactam showed better efficacy. Methicillin-resistant Staphylococcus aureus (MRSA) isolates were sensitive to vancomycin and linezolid. Diabetes, emergency procedures, and prolonged preoperative hospitalization were notable risk factors. This study highlights the substantial burden of SSIs and the growing challenge of antimicrobial resistance. Routine surveillance, individualized antibiotic therapy, and optimization of perioperative practices are essential for improving surgical outcomes.
Surgical Site Infections (SSIs) are among the most frequently encountered healthcare-associated infections (HAIs), especially in low- and middle-income countries. The World Health Organization (WHO) reports that SSIs affect nearly one-third of surgical patients in developing regions, resulting in considerable clinical and economic burden (1). The term "surgical site infection" was standardized by the Centers for Disease Control and Prevention (CDC) in 1992, encompassing infections occurring within 30 days post-surgery or within one year if an implant is involved (2).
In India, the incidence of SSIs has been reported to range from 4% to 30%, depending on hospital setting, patient comorbidities, and infection control practices (3). Factors such as diabetes, prolonged hospitalization, emergency procedures, and contaminated wounds significantly increase SSI risk (4). The rising prevalence of antimicrobial resistance further complicates treatment, particularly due to multidrug-resistant organisms such as methicillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum beta-lactamase (ESBL)-producing Gram-negative bacilli (5,6).
Previous studies in India have consistently shown that Escherichia coli, Staphylococcus aureus, and Klebsiella pneumoniae are the predominant organisms isolated from SSIs, with variable resistance profiles to commonly prescribed antibiotics (7,8). These findings highlight the need for localized microbiological surveillance to guide empirical therapy and antibiotic stewardship efforts.
Objective Of the Study:
This prospective study was undertaken to assess the incidence of SSIs, identify associated risk factors, characterize the microbial profile, and evaluate the antimicrobial susceptibility patterns among general surgery patients at Government Medical College Hospital, Nagapattinam.
MATERIALS AND METHODS:
This prospective observational study was conducted in the Department of General Surgery, Government Medical College Hospital, Nagapattinam, Tamil Nadu, over a period of six months, from April 2024 to September 2024. The study received approval from the Institutional Human Ethics Committee with proposal number GMCN/IEC/2024/1/38 prior to commencement. A total of 150 post-operative patients aged between 18 and 65 years, admitted for various surgical procedures, were enrolled based on inclusion and exclusion criteria.
Inclusion Criteria:
Exclusion Criteria
Study Design and Data Collection
Eligible patients were prospectively evaluated from the time of admission through discharge. A structured case record form was used to capture demographic data (age, gender, BMI), social habits (smoking, alcohol), comorbidities (diabetes, hypertension), wound classification, prophylactic antibiotic use, type and duration of surgery, and hospital stay. Patients were then stratified into two groups: those who developed SSIs and those who did not.
Aseptic wound swab or pus samples were obtained from patients with suspected SSIs and promptly sent to the microbiology laboratory for analysis. Samples were cultured on blood agar and MacConkey agar and incubated aerobically at 37°C for 24 to 48 hours. Organisms were identified using standard biochemical tests. Antimicrobial susceptibility testing was performed by the Kirby-Bauer disc diffusion method on Mueller-Hinton agar, and results were interpreted as per Clinical and Laboratory Standards Institute (CLSI) 2023 guidelines.
Multidrug-resistant organisms such as MRSA and ESBL producers were specifically identified and documented.
Statistical Analysis
All data were entered and managed using Microsoft Excel 2013. Descriptive statistics, including frequency and percentage, were used to summarize demographic characteristics, risk factors, and antimicrobial susceptibility patterns. Graphical representations such as bar diagrams and pie charts were used where appropriate.
RESULTS:
1. Overall Incidence of Surgical Site Infections:
Out of the 150 cases collected during the study period, 70 patients were found to have surgical site infections. The overall incidence of surgical site infections during the study period is 46.6%. This is illustrated in Table 1 and Figure 1.
Table 1: Incidence of Surgical Site Infections
|
Event |
No. of patients |
Percentage |
|
SSI |
70 |
46.6% |
|
No SSI |
80 |
53.4% |
|
Total |
150 |
|
2. Age And Gender Distribution:
Out of the 150 patients, 91 (60%) were male and 59 (40%) were female. SSIs occurred more frequently in males (63%) than in females (37%). This is illustrated in Table 2 and Figure 2.
The highest incidence of SSIs was observed in the 50–60 years age group (43%), followed by 40–50 years (31%) and 30–40 years (17%). This is illustrated in Table 3 and Figure 3.
Figure 1 Incidence of Surgical Site Infections
Table 2 Gender Distribution of Patients
|
Patient Gender |
Total no. of patients n= 150 |
SSI Event n= 70 |
|
Male |
91 (60%) |
44(63%) |
|
Female |
59 (40%) |
26 (37%) |
Figure 2 Gender Distribution of Patients
Table 3 Age Distribution of Patients
|
Patient Age |
Total no. of patients(%) n= 150 |
SSI Event(%) n= 70 |
|
20-30 |
18 (12%) |
6 (9%) |
|
30-40 |
28 (19%) |
12 (17%) |
|
40-50 |
42 (28%) |
22 (31%) |
|
50-60 |
62 (41%) |
30 (43%) |
Figure 3 Age Distribution of Patients
3. Risk Factor Analysis
Out of the 150 patients studied, 85 (57%) patients were found to be alcoholic, and 65 (43%) patients were found to be smokers. In the 70 patients identified with surgical site infections, 50(71%) patients were alcoholic, and 20(29%) patients were found to be smokers.
Higher predominance of surgical site infection was among alcohol consuming patients than smokers. This is shown in Table 4 and Figure 4.
Table 4 Social Habit Distribution of Patients
|
Social Habit |
Total no. of patients(%) n= 150 |
SSI Event(%) n= 70 |
|
Alcohol |
85 (57%) |
50 (71%) |
|
Smoking |
65(43%) |
20 (29%) |
Figure 4 Social Habit Distribution of Patients
Out of the 150 patients, 95(63%) patients had Diabetes, and 55(37%) patients had hypertension. Among the 70 surgical site infected patients, 46(66%) were found to be Diabetic and 24(34%) were found to have Hypertension. The rate of surgical site infections was high among Diabetic patients. This is illustrated in Table 5 and Figure 5.
Table 5 Comorbidity Distribution of Patients
|
Comorbidity |
Total no. of patients(%) n= 150 |
SSI Event(%) n= 70 |
|
Diabetes Mellitus |
95 (63%) |
46 (66%) |
|
Hypertension |
55 ( 37%) |
24 (34%) |
Figure 5 Comorbidity Distribution of Patients
Out of 150 patients, 58 have undergone Elective surgery and 92 have undergone Emergency surgery. Among 70 surgical site infected patients, 15 (21%) patients underwent elective surgery, and 55 (79%) patients underwent emergency surgery.
The rate of surgical site infection was higher in emergency surgeries (79%) when compared to elective surgeries. This is illustrated in Table 6 and Figure 6.
Table 6 Type of Surgery Distribution in Patients
|
Surgery type |
Total no. of Patients(%) n= 150 |
SSI Event(%) n= 70 |
|
Emergency |
92 (61%) |
55 (79%) |
|
Elective |
58 (39%) |
15 (21%) |
Figure 6 Type of Surgery Distribution of Patients
4. Prophylactic antibiotics used for the prevention of surgical site infections.
Several antibiotic agents are given before a surgical procedure to prevent the occurrence of surgical site infections. The most commonly prescribed antibiotics are mentioned in the table and figure below.
The most commonly prescribed antibiotics for surgical prophylaxis of infection include.
This is illustrated in Table 7 and Figure 7.
Table 7 Usage of Prophylactic Antibiotics
|
Antibiotics |
Total no. of patients n= 150 |
|
Metronidazole |
135 (90%) |
|
Cefotaxime |
80 (54 %) |
|
Ceftriaxone |
76 (51%) |
|
Piperacillin Tazobactam |
56 (37 %) |
|
Amikacin |
40 (27%) |
|
Cefoperazone Sulbactam |
35 ( 23%) |
|
Ciprofloxacin |
33 (22%) |
|
Gentamicin |
11 ( 20%) |
|
Doxycycline |
10 (7%) |
Figure 7 Usage of Prophylactic Antibiotics
5. Bacteriology of Surgical Site Infections:
In the 70 patients detected with surgical site infections, the organisms responsible for causing surgical site infections are;
This is illustrated in Table 8 and Figure 8.
Table 8 Types of Bacteria Causing Surgical Site Infections
|
Type of Microbe |
No. of Microbes (%) |
|
Gram Negative |
55 (79%) |
|
Gram Positive |
15 (21%) |
Out of the 15 Gram positive bacteria isolated, Streptococcus aureus is the only strain isolated. A large proportion of Methicillin Resistant Staphylococcus aureus have been detected. The distribution is illustrated in Table 9.
Streptococcus aureus accounts for 20% of all the infections. Methicillin Resistant Staphylococcus aureus accounts for 80% of all the infections.
Table 9 Distribution of Gram-Positive Bacteria
|
Gram Positive n=15 |
No of microbes |
Percentage(%) |
|
Methicillin Resistant Staphylococcus aureus |
12 |
80% |
|
Staphylococcus aureus |
3 |
20% |
Out of the 55 Gram negative bacteria detected Escherichia coli(E coli) is the most predominant strain accounting for 29% of all the infections. This is followed by Klebsiella pneumonia accounting for 21% of all the infections and Pseudomonas aeruginosa accounting for 18% of all the infections. The distribution of various Gram-negative bacteria is illustrated in the below table and figure.
Table 10 Distribution of Gram-Negative Bacteria
|
Gram Negative n= 55 |
No. of Microbes |
Percentage |
|
Escherichia coli |
16 |
29% |
|
Klebsiella pneumonia |
12 |
21% |
|
Pseudomonas aeruginosa |
10 |
18% |
|
Proteus mirabilis |
5 |
9% |
|
Proteus vulgaris |
4 |
7% |
|
Klebsiella oxytoca |
4 |
7% |
|
Citrobacter species |
4 |
7% |
Figure 8 Distribution of Gram-Negative Bacteria
4. Antibiotic Sensitivity of Gram-Positive Bacteria
Most of the gram-positive bacteria showed a maximum of 100% sensitivity to doxycycline followed by 67% sensitivity to Cotrimoxazole, 33% sensitivity to Clindamycin and Linezolid. 17% sensitivity was observed for Azithromycin and Erythromycin.
Staphylococcus aureus showed high sensitivity to Doxycycline (100%) and Cotrimoxazole (67%). Methicillin Resistant Staphylococcus aureus showed high sensitivity to Doxycycline (75%) and Linezolid (33%).
Table 11 Antibiotic Sensitivity of Gram-Positive Bacteria
|
Antibiotics |
Methicillin Resistant Staphylococcus aureus n= 12 |
Staphylococcus aureus n= 3 |
|
Doxycycline |
9 (75%) |
3 (100%) |
|
Cotrimoxazole |
3 (25%) |
2 (67%) |
|
Azithromycin |
2 (17%) |
0 (0%) |
|
Linezolid |
4 (33%) |
0 (0%) |
|
Erythromycin |
2(17%) |
0 (0%) |
|
Clindamycin |
2 (17%) |
1 (33%) |
5.Antibiotic Sensitivity of Gram-Negative Bacteria
The Gram-negative bacteria were highly sensitive to ciprofloxacin (66.6%) followed by Gentamicin (56.25%), Piperacillin Tazobactam (55.5%)
The most commonly isolated Gram-negative bacteria E.coli showed high sensitivity to Ciprofloxacin (56.25%) followed by Piperacillin Tazobactam and Gentamicin (50%)
Klebsiella spp showed high sensitivity to Gentamicin (56.25%) followed by Ciprofloxacin and Piperacillin Tazobactam (31.25%)
Pseudomonas spp showed high sensitivity to Ciprofloxacin and Gentamicin (40%).
Proteus spp showed high sensitivity to Ciprofloxacin (66.6%) followed by Piperacillin Tazobactam (55.5%) and Cotrimoxazole (22.2%)
Citrobacter spp showed high sensitivity to Ciprofloxacin(75%) followed by Piperacillin Tazobactam and Gentamicin (50%).
Table 12 Antibiotic Sensitivity of Gram-Negative Bacteria
|
Antibiotic |
Klebsiella spp n=16 |
E coli n= 16 |
Pseudomonas Spp n= 10 |
Proteus spp n= 9 |
Citrobacter spp n= 4 |
|
Cefoperazone sulbactam |
1 (6.2%) |
0 (0%) |
0 (0%) |
0 (0%) |
0 (0%) |
|
Ciprofloxacin |
5(31.25%) |
9 (56.25%) |
4 (40%) |
6 (66.6%) |
3 (75%) |
|
Piperacillin Tazobactam |
5 (31.25%) |
8 (50%) |
5 (50%) |
5 (55.5%) |
2 (50%) |
|
Amikacin |
3 (18.75%) |
2 (12.5%) |
0 (0%) |
1 (11.11%) |
0 (0%) |
|
Cotrimoxazole |
3 (18.75%) |
3 (18.75%) |
0 (0%) |
2 (22.2%) |
0 (0%) |
|
Gentamicin |
9 (56.25%) |
8 (50%) |
4 (40%) |
1(11.1%) |
2 (50%) |
|
Meropenem |
0 (0%) |
4(25%) |
0 (0%) |
0 (0%) |
0 (0%) |
|
Cefotaxime |
3 (18.75%) |
0 (0%) |
0 (0%) |
0 (0%) |
0 (0%) |
DISCUSSION
Surgical Site Infections (SSIs) continue to be a significant cause of postoperative morbidity, especially in resource-limited healthcare settings. In the present study conducted over a six-month period in a tertiary care hospital in South India, the incidence of SSIs was found to be 46.6%. This is consistent with previous reports by Patel et al. (40.8%) and Bastola et al. (48.6%), highlighting a similar burden in comparable tertiary care settings [6,9].
Gender-wise distribution revealed a higher incidence of SSIs among males (63%), which aligns with the observations of Naz et al. (60%) and Budhani et al. (56%) [10,11]. The greater vulnerability in males could be attributed to occupational exposure, higher rates of smoking and alcohol consumption, and delayed healthcare-seeking behavior.
Age-related analysis showed that individuals in the 50–60-year age group were most affected, in agreement with findings from Saxena et al., who reported increased SSI risk in older adults due to declining immunity and higher prevalence of comorbidities [12].
Comorbidity analysis indicated that diabetes mellitus (66%) was the most significant risk factor associated with SSIs in this study, echoing the conclusions of Khairy et al. and Giridhar et al., who also identified diabetes as a major contributor to postoperative infections [13,14]. Similarly, 71% of SSI cases were associated with alcohol use, consistent with the study by Reeja Jiji et al., which found alcohol consumption to be a notable behavioral risk factor for poor wound healing [15].
Emergency surgeries accounted for 79% of all SSI cases in the present study. This finding is supported by Thummar et al., who noted a significantly higher incidence of SSIs following emergency procedures, possibly due to inadequate preoperative preparation and compromised aseptic techniques [16].
Antibiotic prophylaxis patterns in this study showed metronidazole as the most commonly administered drug, followed by ceftriaxone. This trend contrasts with the findings of Bastola et al., where ceftriaxone was the most frequently prescribed agent [9]. Such variations could be due to differences in local antibiotic policies or surgeon preference.
Microbiologically, the predominance of Gram-negative organisms (79%) over Gram-positive organisms (21%) aligns with the findings of Chaudhari et al., who reported a Gram-negative dominance of 84.6% in SSI cases [18]. Among Gram-negative isolates, Escherichia coli (29%) was the most frequently identified pathogen, followed by Klebsiella pneumoniae (21%) and Pseudomonas aeruginosa (18%). These results corroborate the microbial patterns reported by Reeja Jiji et al. [15].
Among Gram-positive organisms, Staphylococcus aureus was the most common isolate (20%), with 12 of those identified as Methicillin-resistant S. aureus (MRSA). This is partially consistent with Bastola et al., who documented 14 MRSA isolates among their patient cohort [9].
In terms of antimicrobial susceptibility, ciprofloxacin exhibited the highest efficacy among Gram-negative isolates (66.6%), followed by gentamicin (56.25%) and piperacillin-tazobactam (55.5%). These findings align closely with those of Verma et al., who also observed ciprofloxacin to be the most effective agent (75.76%) [19].
Interestingly, all Gram-positive isolates in the current study showed 100% sensitivity to doxycycline, while sensitivity to linezolid was only 33%. This contrasts with Misbah Najam et al., who reported universal sensitivity of Gram-positive isolates to vancomycin and linezolid [20]. Such discrepancies may reflect local antibiotic resistance trends and warrant further investigation.
Overall, this study reinforces the critical need for ongoing microbiological surveillance and institutional antibiotic stewardship programs to combat rising resistance and optimize patient outcomes. Risk stratification based on comorbidities, age, and surgical factors can further help in SSI prevention.
CONCLUSION
This prospective study highlights a notably high incidence of surgical site infections in a general surgery ward of a tertiary care hospital in South India, with a clear predominance of Gram-negative bacterial isolates. Risk factors such as diabetes mellitus, alcohol consumption, emergency surgeries, and prolonged hospital stays were found to be significantly associated with SSI development. The widespread resistance to commonly used antibiotics—particularly among Gram-negative pathogens—underscores the urgent need for localized antibiotic stewardship and robust infection control practices.
Regular microbiological surveillance, early identification of high-risk patients, and strict adherence to aseptic surgical techniques are crucial in reducing SSI-related morbidity. Empirical antibiotic therapy should be guided by regional antibiograms to ensure optimal patient outcomes and to mitigate the growing threat of antimicrobial resistance.
ACKNOWLEDGMENT
The authors would like to express their sincere gratitude to the Department of General Surgery and the Department of Microbiology, Government Medical College Hospital, Nagapattinam, for their invaluable support and cooperation throughout the course of the study. The authors also extend their thanks to the patients who consented to participate. Special appreciation is extended to Dr.M.Arhoul Rennies, our project guide, for his continued support throughout the study.
CONFLICT OF INTEREST
The authors declare that there is no conflict of interest related to the publication of this manuscript.
REFERENCES
Dr. M. Arhoul Rennies, Fathima Juhaina M Abdul Khader, K. Janani, A. Lakshmikaanthan, A Prospective Study on The Bacteriological Profile and Antimicrobial Susceptibility of Surgical Site Infections in A General Surgery Ward at A Tertiary Care Hospital in South India, Int. J. of Pharm. Sci., 2025, Vol 3, Issue 7, 3044-3055. https://doi.org/10.5281/zenodo.16312921
10.5281/zenodo.16312921
