Abstract
Background:
Surgical site infections (SSIs) are among the most common postoperative complications, significantly impacting morbidity, hospital stay, and healthcare costs. Identifying the microbiological spectrum and resistance patterns is essential for effective management.
Material and Methods:
This prospective observational study was conducted in a tertiary care hospital in Central India among 78 patients who developed SSIs following elective neurosurgical and laparotomy procedures. Pus/wound swab samples were collected aseptically and processed using standard culture methods. Isolates were identified, and antibiotic susceptibility testing was performed as per CLSI guidelines.
Results:
Among 78 samples, 62.8% showed growth. E. coli (21.8%) and S. aureus (19.2%) were the most common isolates. Concomitant infections included UTI (46.5%), BSI (51.2%), and VAP (7%). E. coli showed 82.3% sensitivity to piperacillin-tazobactam and 53% to amikacin. S. aureus was 100% sensitive to vancomycin and linezolid. Klebsiella and Pseudomonas showed 75% and 42.8% sensitivity to piperacillin-tazobactam, respectively. Acinetobacter showed 50% sensitivity to meropenem.
Conclusion:
Gram-negative organisms, particularly E. coli and Klebsiella, were the leading SSI pathogens, with significant resistance to cephalosporins and carbapenems. The high MRSA prevalence highlights the need for stringent infection control and targeted antibiotic stewardship.
KEYWORDS: Antibiotic resistance, MRSA, surgical site infection
INTRODUCTION
Surgical site infections (SSIs) remain a prevalent healthcare-associated complication, frequently contributing to increased morbidity, extended hospital stays, and elevated healthcare costs, particularly in Indian tertiary centers.[1] The microbiological spectrum of SSIs in India often reveals a predominance of Gram-negative organisms such as Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii, alongside Gram-positive Staphylococcus aureus.[2,3] High rates of multidrug resistance, including extended-spectrum β-lactamase (ESBL) producers and carbapenem-resistant non-fermenters, have been increasingly documented.[3,4] In many reports, S. aureus remains the leading Gram-positive isolate, while E. coli frequently predominates among Gram-negatives, especially in abdominal surgery cases.[4,5] Given these evolving patterns, local documentation of pathogen prevalence and antimicrobial sensitivity is essential to guide empirical therapy. This study characterizes the bacteriological profile and resistance patterns of pathogens causing SSIs following elective neurosurgery and laparotomy in a tertiary care hospital in Central India.
MATERIALS AND METHODS
This prospective observational study was conducted over one year at Mahatma Gandhi Memorial Medical College and Maharaja Yeshwant Rao Hospital, Indore, following ethical clearance. Patients undergoing elective laparotomy or neurosurgery were included, while those undergoing day-care procedures or discharged within 72 hours postoperatively were excluded.
Eligible patients were assigned unique identification codes. Relevant clinical and demographic data were collected, including comorbidities and surgical details. Surgical site infections (SSIs) were identified based on CDC/NHSN criteria during postoperative follow-up, starting from the third postoperative day or at the first dressing change, per institutional protocol.
In all confirmed SSI cases, wound swabs or pus samples were collected using aseptic technique and sent for microbiological evaluation. Isolates were identified using standard culture and biochemical methods. Antibiotic susceptibility testing was performed using the Kirby-Bauer disc diffusion method in accordance with CLSI guidelines.
Microbial profiles and resistance patterns were documented and analyzed to determine prevalent organisms and their drug susceptibility. Patients were followed until discharge, death, or leaving against medical advice (LAMA).
OBSERVATION AND RESULTS
Among the 78 surgical samples analyzed, the most common isolate was E. coli (17 cases), predominantly found in sero-sanguinous fluids, while 29 samples showed no microbial growth [Figure 1]. In patients with surgical site infections (SSI) and concomitant infections, E. coli was most frequently associated with UTIs (14 cases), whereas Staphylococcus species were mainly linked with bloodstream infections (12 cases) [Figure 2]. E. coli isolates showed highest sensitivity to meropenem (82.3%), while Staphylococcus aureus showed full sensitivity to vancomycin and linezolid; resistance was notable among other isolates, especially Acinetobacterbaumannii complex [Table 1].
Figure 1.
Distribution of organisms isolated from different samples
Figure 2.
Microbiological etiology of concomitant SSI
Table 1.
Sensitivity pattern of isolated organisms to various antibiotics (%)
| Organism (n) | Cefoxitin | Ceftriaxone | Amikacin | Piperacillin + Tazobactam | Meropenem | Clindamycin | Vancomycin | Linezolid | Ciprofloxacin | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Escherichia coli (17) | 3 (17%) | 7 (41%) | 9 (53%) | 14 (82.3%) | – | – | – | – | 8 (47%) | |||||||||
| Staphylococcus aureus (15) | – | 1 (6.6%) | – | – | – | 9 (60%) | 15 (100%) | 15 (100%) | 9 (60%) | |||||||||
| Klebsiellapneumoniae (04) | 0 (0%) | 1 (25%) | 0 (0%) | 3 (75%) | – | – | – | – | 1 (25%) | |||||||||
| Pseudomonas aeruginosa (07) | – | 3 (42.8%) | 2 (28.5%) | 3 (42.8%) | – | – | – | – | 1 (14.2%) | |||||||||
| Acinetobacterbaumannii (06) | – | 2 (33.3%) | – | 2 (33.3%) | 3 (50%) |
DISCUSSION
In our cohort, Escherichia coli predominated among SSI isolates (17/78), particularly from sero-sanguinous fluids, consistent with other Indian studies highlighting E. coli as a leading Gram-negative pathogen in SSIs.[6] Staphylococcus aureus (15 isolates), frequently recovered from tissue specimens, aligns with its known role as a common Gram-positive SSI pathogen.[6] Alarming detection of Pseudomonas spp. (7) and Acinetobacter baumannii complex (6) reflects increasing prevalence of non-fermenters in postoperative wound infections across tertiary centres in India.[3,6]
Concomitant infection analysis revealed E. coli dominating UTIs (14/20), while S. aureus was the principal isolate in BSIs (12/22), indicating distinct pathogen tropisms depending on infection site. This echoes prior observations that E. coli drives urinary infections whereas S. aureus is more implicated in bloodstream involvement.[7]
Antibiotic susceptibility patterns showed E. coli isolates largely susceptible to meropenem (82%), and S. aureus uniformly sensitive to vancomycin and linezolid—mirroring resistance trends in Indian tertiary care settings.[8] However, reduced sensitivity of Acinetobacterbaumannii (only 50% to meropenem, 33% to piperacillin-tazobactam) underscores the challenges posed by multidrug-resistant non-fermenters. Carbapenem resistance in A. baumannii is well documented in South India, mediated by bla_OXA and bla_NDM-1 genes.[9]
These findings underscore the urgent need for active microbiological surveillance, tailored antibiotic stewardship, and infection control targeting Gram-negative and non-fermenting pathogens in SSI management.
CONCLUSION
Surgical site infections remain a significant concern, with a prevalence of 15.53% in elective neurosurgical and laparotomy cases in our tertiary care setting. Diabetes mellitus, prolonged surgical duration, and laparotomy procedures were major contributors to increased SSI risk. Strengthening infection control practices and ensuring strict adherence to perioperative antibiotic protocols are essential to reduce SSI incidences.
Conflicts of interest
There are no conflicts of interest.
Funding Statement
Nil.
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