Surgical site infections (SSIs) are among the most prevalent complications following surgical procedures, representing a major component of nosocomial infections 2. Each year, a significant amount of morbidity and mortality is caused by infection at or around the surgical site, which occurs within 30–90 days of an operative procedure (or within one year of an implant used) 3.

Despite improvements in surgical techniques, sterilization of instruments, operation theatre practices, and the best efforts of infection prevention practices, SSIs remain a major cause of hospital-acquired infections 4. These are further complicated by an increasing prevalence of multidrug-resistant organisms. Most of the time, it is the patient’s endogenous flora that is responsible for many SSIs, and the commonly isolated pathogens include Staphylococcus aureus, coagulase-negative staphylococci, Enterococcus sp., and Escherichia coli 1.

However, the identification of factors that cause or predict these SSIs remains an important area of research. We aim to investigate the risk factors for SSIs, together with the identification of the etiological bacterial agents and their antimicrobial susceptibility in a tertiary hospital.

A prospective, cross-sectional study was conducted for one year from January 2023 to December 2023 at a tertiary care centre, Mangalore.

In the present study, 87 clinically diagnosed cases of SSIs were studied for one year (January 2023 to December 2023) in all age groups and sexes. Based on age-wise and gender wise distribution out of 87 samples (Table 2), 59 (68.6%) were males and 28 (31.4%) were females. Among 87 cases, 32.6% were of the age group 41-50 Years, of which 16 (18.6%) were males and 12 (14.0%) females. The age group of 51-60 was showing 17 cases, of which 11 (12.8%) were males and 6 (7.0%) were females. On the other hand, the age group 31-40 years showed 13 cases. 0f which 10 (11.6%) were males and 3 (2.3%) were females. According to this data, the age group of 41-50 years showed a higher percentage (32.6%) of SSIs, and the incidence was higher in male than female patients (Figure 1).

Out of 87 cases of Bacterial isolates, culture-positive cases were 54 (62.07%) and culture-negative cases were 33 (37.93%) (Figure 2).

Table 1

Microorganisms Isolated	Frequency	Percentage (%)
No growth	33	38.4
Staphylococcus aureus	23	25.6
E. coli	12	14
Pseudomonas	9	10.5
Enterobacter	4	4.7
Klebsiella	2	2.3
CoNS	2	2.3
Proteus	2	2.3
Total	87	100

Staphylococcus aureus was the most predominant microorganism isolated (25.6%) followed by E. coli (14.0%) and Pseudomonas sp. (10.5%). Very few cases of Enterobacter (4.7%), Klebsiella, CoNS, and Proteus (2.3%) were reported. All microorganism isolates were tested for antimicrobial sensitivity testing and the results were interpreted according to standard value by CLSI6 (Table 1).

The majority of the SSI patients (49%) were from General surgery (40 cases), most of which were abdominal surgeries. Plastic surgery was 13 cases (14%), Orthopedics and gynecology with each of 10 cases (11%), and cardiovascular with 9% cases. The minority of the surgeries (6%) were from Pediatrics (6 cases) (Table 2). Certain underlying conditions like anaemia, smoking with a history of tobacco chewing, with chronic cough, diabetes with obesity, and hypertension may alter or decrease the immune status, thus significantly increasing the risk of SSI. They are also an important cause of increasing the pre-operative stay of the patient, which steeply increases the risk of SSI in such patients. In our study, 7.6% of patients with SSI had some underlying conditions, anaemia and diabetes mellitus being the commonest.

Isolates of Staphylococcus aureus were found to be 100% sensitive towards Tetracycline and Linezolid, 23 (100%) and 5 isolates (22%) were reported as MRSA. CoNS were sensitive to most of the antibiotics, and no Methicillin-resistant strains were detected. CoNS was reported based on clinical correlation and discussion with the clinician (Table 3).

Among E. coli, 4 isolates (33%) were found to be ESBL producers and were sensitive towards Amikacin, Gentamicin, and Meropenem, and most of them were resistant to Ciprofloxacin and Tetracycline. Most of the Isolates of Pseudomonas (77.7%) were found to be maximally sensitive towards Imipenem, Meropenem, Ciprofloxacin, and other antibiotics but resistant (66.7%) to Cephalosporins (Table 4).

SSIs are the most common hospital-acquired infection and could be superficial, involving skin and subcutaneous tissue, or a serious infection involving deeper tissues, organs, or the implant itself 7. In developing countries, the incidence rates of SSIs range from 1.2 to 23.6 per 100 surgical procedures 8. Several studies across India have reported SSI rates ranging from 0.04–22.00% 9, 10. Our study reported 2.2% of SSIs, similar to a study by Trrisha et al 1. A study by Sathyanarayan et al 11 showed a rate of 13.7% SSIs, which was much higher than our study.

The current study confirms that SSIs were predominantly seen in male patients, those in the 41-50 year age group. The finding obtained in the study of Nidhi Pal et al 12 found that the model age group was 31- 60 years with a frequency of 102 (49.5%) out of 206, which is similar to findings in our study. Male predominance could be attributed to occupational exposure, comorbidities, or lifestyle-related risk factors. The study conducted by Rama Bastola et al in New Delhi, India, also showed that out of 206 samples 65.04% were from males and 34.90% were from female patients 13.

In our study, the highest number of surgical site infection was from general surgery 40 (49%), followed by plastic surgery 13 (14%), 10 from orthopedics, obstetrics and gynecology (11%), 8 (9%) from cardiovascular surgery and 6 (6%) from pediatric surgery. A similar result was obtained in a study carried out by Chenna Krishna Reddy Chada et al14 in Andhra Pradesh, who reported SSI of 41.18% from the general surgical ward, 32.6% from orthopedics & 26.4% from the gynecology ward. SSIs were common in abdominal surgeries from the general surgery and gynecology ward, which is similar to a study done by Allegranzi et al15 who also reported that abdominal surgeries have high rates of SSIs due to contamination with endogenous flora.

In our study, among 54 culture-positive samples, 25 (29%) were Gram-positive and 29 (33.4%) were Gram-negative bacteria. A similar result was obtained by Akther MS et al, conducted in Mumbai, where Staphylococcus aureus, Escherichia coli, and Klebsiella sp. were the most common organisms 16. In the present study, the most common pathogen was Staphylococcus aureus (25.6%), followed by E. coli (14%), Pseudomonas species (10.5%), Enterobacter (4.7%), Klebsiella, CoNS, and Proteus each of (2.3%). Staphylococcus aureus has been the most common organism isolated from SSI over the decades and across the continent. In a study carried out by T. Gridhar et al 17 in Kadapa, Staphylococcus aureus was the commonest organism, accounting for 22% of all isolates.

Our study showed Staphylococci 100% sensitive to Tetracycline and Linezolid, and all isolates were resistant to Penicillin. This is similar to the study findings by Mundhada and Tenpe 18. Out of 23 isolates, 5 (22%) were reported as MRSA, similar to a study by Bhattacharya.S et al in West Bengal 18.

Gram-negative bacteria are multidrug-resistant Enterobacteriaceae, which display a high magnitude of resistance to multiple antibiotics. In our study E. coli showed 33% resistance to β-lactam antibiotics (ESBL producers), and both the isolates of Klebsiella species showed 100% resistance to β-lactam antibiotics (ESBL producers). Among them, E. coli and Klebsiella species were 100% sensitive to Carbepenems and Aminoglycosides, but Proteus species were resistant to Carbepenem and Aminoglycosides. This was similar to the study of Shahane V et al, where the Enterobacteriaceae showed very low sensitivity to cephalosporins and fluoroquinolones (10% and 58%, respectively). This could be due to the overuse of these drugs and the high prevalence of extended-spectrum beta-lactamases (ESBLs) among these organisms 19. Multi-drug resistant Klebsiella and carbapenem-resistant Klebsiella are important hospital pathogens causing SSI.

This study highlights that surgical site infections, though relatively controlled in incidence (2.2%), continue to pose a challenge due to evolving microbial profiles and resistance patterns. The predominance of S. aureus, followed by E. coli and Pseudomonas aeruginosa, necessitates targeted prophylactic and therapeutic interventions.

Key recommendations include:

Reducing the burden of SSIs through these interventions will significantly improve surgical outcomes and optimize healthcare resources.