1Department of General Surgery, Government Medical College Hospital, Nagapattinam.
2,3,4Department of Pharmacy Practice, EGS Pillay College of Pharmacy, Nagapattinam.
This prospective observational study was conducted over a six-month period in a tertiary care teaching hospital to evaluate antibiotic resistance patterns and review antibiotic utilization among inpatients. A total of 364 clinical samples from patients aged 18 to 70 years were analyzed to identify priority pathogens and assess their resistance profiles. Gram-negative bacilli such as Escherichia coli, Klebsiella species, and Pseudomonas aeruginosa showed high resistance to cephalosporins, aminoglycosides, and fluoroquinolones, with some strains exhibiting resistance even to last-resort drugs like carbapenems. Alarmingly, emerging resistance was also noted in traditionally sensitive organisms, including reduced susceptibility to piperacillin-tazobactam and linezolid in certain Enterococcus and Klebsiella isolates. Gram-positive cocci such as Staphylococcus aureus and Streptococcus species displayed increasing resistance to beta-lactams and macrolides, raising concerns about the future effectiveness of standard treatment options. Empirical antibiotic use was dominated by cephalosporins (82.7%) and imidazoles, while post-culture modifications favoured aminoglycosides and carbapenems, highlighting the role of culture sensitivity in guiding therapy. Comorbidities such as diabetes mellitus and anemia were common, increasing vulnerability to infections and complicating treatment. The study emphasizes the critical need for ongoing antimicrobial resistance surveillance and stricter antibiotic stewardship programs to curb the spread of emerging resistance. Integrating microbiological data into clinical decision-making proved essential for optimizing therapy and improving patient outcomes in the face of evolving resistance challenges.
Antibiotics have revolutionized modern medicine since their discovery in the early 20th century. However, the growing threat of antibiotic resistance (AR) poses a serious global challenge. AR occurs when bacteria evolve mechanisms to withstand the effects of antibiotics, rendering standard treatments ineffective and leading to prolonged illness, increased healthcare costs, and higher mortality rate1. Inappropriate and excessive use of antibiotics-particularly in hospital settings has accelerated the development of resistant pathogens such as Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus2,3. Tertiary care hospitals often report high resistance levels due to empirical antibiotic use without culture sensitivity guidance4. India is among the countries with the highest burden of multidrug-resistant organisms (MDROs), especially in South Indian hospitals, where resistance to beta-lactams, fluoroquinolones, and even carbapenems is alarmingly high5. Factors contributing to this include over-the-counter antibiotic access, lack of awareness, and inadequate infection control6. This study aims to monitor local resistance patterns and review antibiotic utilisation to improve antimicrobial stewardship. Emphasizing culture-guided therapy is essential to optimize prescribing practices and curb the rise of AR in clinical settings7.
Aim And Objective Of The Study: This study aimed to assess antibiotic resistance patterns and evaluate prescribing practices in a tertiary care hospital. It focused on analyzing culture reports, identifying resistant pathogens, and reviewing antibiotic use before and after sensitivity results. The objective was to support rational antibiotic use, minimize resistance, and enhance antimicrobial stewardship.
MATERIALS AND METHODS:
Study design
This was a prospective observational study conducted over a six-month period, from August 2024 to January 2025, in the General Medicine Inpatient Department of a tertiary care teaching hospital located in Nagapattinam, Tamil Nadu. A total of 364 patients were enrolled based on predefined inclusion and exclusion criteria.
Inclusion and exclusion criteria
Inclusion criteria included patients aged between 18 and 70 years, of either gender, who were admitted to the inpatient department and prescribed antibiotics with a recommendation for culture sensitivity testing. Exclusion criteria included patients not prescribed antibiotics, pregnant women, and individuals co-infected with tuberculosis or sexually transmitted diseases.
Data collection procedures
Clinical samples such as blood, urine, sputum, wound swabs, and body fluids were collected aseptically from the relevant anatomical sites using standard infection control practices to ensure accuracy and prevent contamination. All specimens were processed in the hospital’s microbiology laboratory, and culture and sensitivity testing were carried out using standard microbiological techniques. Data collection was done using a structured case record form, which included demographic details, medical history, diagnosis, comorbidities, antibiotic therapy details (both empirical and post-culture), and microbiological findings, including resistance patterns. Antibiotic utilization was reviewed at two stages—initial empirical therapy and the revised therapy based on culture sensitivity reports. The impact of culture-guided therapy on antibiotic selection and resistance management was analyzed.
Data interpretation
Data were organized and processed using Microsoft Excel 2021. Basic statistical methods such as counts and percentages were applied to describe patient demographics, associated risk factors, antibiotic prescribing trends, and resistance patterns. Visual tools like bar graphs and pie charts were used to illustrate the findings effectively.
Ethical approval
The study received ethical clearance from the Institutional Ethics Committee of Government Medical College Hospital, Nagapattinam, registered under PR. NO.-ECNEW/INSTI2022/2367, with IEC approval number GMCN/IEC/2024/1/35 dated 23-07-2024. The investigation was conducted in full compliance with the ethical standards and guidelines prescribed by the committee.
RESULTS:
Age and gender distribution:
The study included a total of 364 patients admitted to the General Medicine ward over a six-month period. The population consisted of 209 males (57.42%) and 155 females (42.58%), indicating a male predominance. Most patients fell within the 60–70 years age group (33.52%), followed by those aged 50–60 years (24.73%), highlighting the vulnerability of older adults to infectious diseases and the increased need for antibiotic therapy. Age wise distribution illustrated in Table 1.
Table 1: Age Wise Distribution
|
Age groups |
No. of patients |
Percentage % |
|
20 - 30 |
75 |
20.60% |
|
30 - 40 |
35 |
9.62% |
|
40 - 50 |
42 |
11.53% |
|
50 - 60 |
90 |
24.73% |
|
60 - 70 |
122 |
33.52% |
Drug utilisation data of antibiotics
Before the availability of culture sensitivity results, empirical antibiotic therapy (illustrated in Table 2) was administered based on clinical judgment. Cephalosporins were prescribed most frequently (82.70%), followed by imidazoles (38.75%) and penicillins (11.20%). A total of 364 patients, 187 patients (51.37%) received a single antibiotic, while 177 patients (48.63%) were prescribed two antibiotics. This reflects the tendency to initiate broad-spectrum therapy to cover possible pathogens before microbiological confirmation.
Table 2: Antibiotics Prescribed Before Culture Test
|
Antibiotic classes |
Total no. of patients received |
Percentage % |
|
Cephalosporin |
301 |
82.70% |
|
Penicillins |
41 |
11.20% |
|
Aminoglycosides |
6 |
1.60% |
|
Quinolones |
26 |
7.10% |
|
Imidazoles |
141 |
38.75% |
|
Sulfonamides |
26 |
7.10% |
After culture reports were obtained, prescribing patterns (illustrated in Table 3) were significantly adjusted. A majority of patients (242; 66.48%) continued to receive a single antibiotic, reflecting the importance of targeted therapy based on specific pathogen sensitivities. Meanwhile, 99 patients (27.20%) were prescribed two antibiotics, and 23 patients (6.32%) received three antibiotics. Although cephalosporins remained the most prescribed class (30.50%), their usage dropped notably. Aminoglycosides (23.62%), penicillins (25.00%), quinolones (16.75%), and carbapenems (8.24%) were more frequently administered based on culture sensitivity, indicating a move toward targeted therapy.
Table.3 Antibiotics Prescribed After Culture Test
|
S. N0. |
Antibiotic Class |
No. Of Time Prescribed |
Percentage% |
|
1 |
Aminoglycosides |
86 |
23.62% |
|
2 |
Carbapenam |
30 |
8.24% |
|
3 |
Cephalosporin |
111 |
30.50% |
|
4 |
Imidazoles |
40 |
10.98% |
|
5 |
Macrolides |
1 |
0.27% |
|
6 |
Oxazolidinones |
27 |
7.42% |
|
7 |
Penicillin |
91 |
25.00% |
|
8 |
Quinolones |
69 |
16.75% |
|
9 |
Sulfonamides |
23 |
6.32% |
|
10 |
Tetracycline |
31 |
8.52% |
Comorbidity
Diabetes Mellitus was the most prevalent co-morbidity, observed in 89 patients (24.45%). This high prevalence aligns with existing literature that links diabetes to an increased risk of infections due to impaired immune response, poor glycemic control, and increased exposure to healthcare settings. Anemia was found in 53 patients (14.56%), reflecting its frequent occurrence among patients with chronic illnesses or malnutrition, which can compromise immune function and increase susceptibility to infections. Patients with COPD or asthma who require mechanical ventilation are at a higher risk of developing antibiotic-resistant infections. The frequent use of ventilators and recurrent use of steroids increases exposure to hospital-acquired pathogens, such as Pseudomonas aeruginosa and Staphylococcus aureus, which are often resistant to multiple antibiotics. Other comorbidity are illustrated in figure 1.
Fig 1 prevalence of priority pathogens
Specimen wise isolation of priority pathogens
The specimen-wise isolation of priority pathogens (table 4) reveals a diverse distribution across various clinical samples, highlighting the complexity of hospital-acquired infections (HAIs). When compared to findings in existing literature, some interesting patterns and differences emerge.
Table.4 Specimen Wise Isolation of Priority Pathogens
|
Priority Pathogen |
Pus Cells |
Urine |
Wound Cells |
Ascites Fluid |
CSF Fluid |
Pleural Fluid |
Sputum |
|
Acinetobacter baumannii |
3 |
1 |
5 |
4 |
5 |
6 |
5 |
|
Citrobacter sp |
8 |
5 |
2 |
6 |
0 |
2 |
4 |
|
E.coli |
11 |
7 |
3 |
4 |
6 |
2 |
9 |
|
Enterococcus sp |
3 |
4 |
4 |
2 |
7 |
2 |
3 |
|
Klebsiella sp |
14 |
13 |
8 |
6 |
8 |
3 |
9 |
|
MR Coagulase negative staphylococcus |
3 |
0 |
0 |
0 |
0 |
0 |
1 |
|
MR Staphylococcus aureus |
6 |
6 |
4 |
3 |
1 |
8 |
3 |
|
Proteus sp |
9 |
3 |
4 |
6 |
1 |
3 |
6 |
|
Pseudomonas sp |
14 |
8 |
3 |
5 |
2 |
7 |
7 |
|
Staphylococcus sp |
3 |
6 |
2 |
2 |
2 |
5 |
4 |
|
Streptococcus sp |
4 |
7 |
7 |
9 |
10 |
2 |
3 |
Resistance profile of gram-negative bacilli
Gram-negative bacilli, such as Escherichia coli (E. coli), Klebsiella species, Proteus species, and Pseudomonas aeruginosa, are significant causes of healthcare-associated infections, including urinary tract infections, pneumonia, and bloodstream infections. These bacteria are particularly challenging to treat due to their outer membrane, which restricts antibiotic entry, and their ability to produce enzymes like beta-lactamases that degrade antibiotics. The rise in antibiotic-resistant strains among these organisms is a critical concern, as it complicates treatment options and increases morbidity and mortality rates (Kanj & Kanafani, 2011)(table 5).
Table 5 resistance profile of gram-negative bacilli
|
Drugs |
E.Coli |
Klebsiella sp |
Proteus sp |
Pseudomonas sp |
||||||||
|
|
Total |
R |
R% |
Total |
R |
R% |
Total |
R |
R% |
Total |
R |
R% |
|
amoxicillin |
5 |
4 |
80% |
15 |
10 |
66.67% |
9 |
5 |
55.56% |
6 |
2 |
33.30% |
|
amoxicillin-clavulanate |
6 |
3 |
50% |
15 |
6 |
40% |
11 |
5 |
45.45% |
8 |
4 |
50% |
|
cefotaxime |
19 |
14 |
74% |
21 |
10 |
47.60% |
7 |
4 |
57.14% |
14 |
9 |
64.28% |
|
ceftazidime |
6 |
6 |
100% |
18 |
9 |
50% |
11 |
8 |
72.72% |
15 |
12 |
80% |
|
cefoperazone-sulbactum |
8 |
5 |
62.50% |
19 |
11 |
57.89% |
3 |
2 |
66.67% |
12 |
3 |
25% |
|
doxycycline |
8 |
4 |
50% |
10 |
2 |
20% |
9 |
3 |
33.37% |
8 |
5 |
62.50% |
|
linezolid |
10 |
5 |
50% |
13 |
8 |
61.50% |
6 |
5 |
83.33% |
12 |
6 |
50% |
|
piptaz |
13 |
2 |
15.38% |
25 |
10 |
40% |
9 |
3 |
33.37% |
15 |
5 |
33.30% |
|
ciprofloxacin |
21 |
14 |
52.38% |
24 |
9 |
37.50% |
11 |
6 |
54.54% |
19 |
8 |
42.16% |
|
co-trimoxazole |
14 |
6 |
42.85% |
21 |
10 |
47.60% |
12 |
9 |
75% |
16 |
10 |
62.50% |
|
meropenam |
10 |
8 |
80% |
18 |
10 |
55.50% |
11 |
6 |
54.54% |
9 |
4 |
44.40% |
|
amikacin |
16 |
9 |
56.20% |
13 |
6 |
46.15% |
13 |
6 |
46.15% |
19 |
8 |
42.10% |
|
gentamicin |
9 |
8 |
88.89% |
29 |
13 |
44.82% |
9 |
7 |
77.78% |
19 |
5 |
26.31% |
|
penicillin |
10 |
7 |
70% |
11 |
8 |
72.70% |
6 |
2 |
33.33% |
12 |
7 |
58.30% |
|
clindamycin |
1 |
1 |
100% |
5 |
5 |
100% |
0 |
0 |
0 |
0 |
0 |
0 |
Resistance profile of gram-positive cocci
Gram-positive cocci, including Enterococcus sp., Streptococcus sp., and Staphylococcus sp., frequently show resistance in clinical specimens such as blood, urine, and wound swabs. Enterococcus species exhibit resistance to aminoglycosides, often complicating the treatment of urinary tract infections and bloodstream infections. Streptococcus species, particularly Streptococcus pneumoniae, show resistance to macrolides and beta-lactams, which can affect the management of respiratory tract infections. Staphylococcus species, notably MRSA, demonstrate significant resistance to beta-lactams, complicating skin, soft tissue, and systemic infections. These resistance patterns align with the findings from European surveillance studies, highlighting the need for vigilant monitoring and targeted therapies (table 6).
Table 6 resistance profile of gram-positive cocci
|
Drugs |
staphylococcus sp |
streptococcus sp |
enterococcus sp |
||||||
|
|
Total |
R |
R% |
Total |
R |
R% |
Total |
R |
R% |
|
amoxicillin |
5 |
0 |
0 |
14 |
4 |
28.57% |
10 |
5 |
50% |
|
amoxy-clav |
6 |
4 |
66.67% |
13 |
7 |
53.84% |
4 |
1 |
20% |
|
cefotaxim |
7 |
0 |
0 |
10 |
3 |
30% |
6 |
4 |
66.67% |
|
ceftazidime |
6 |
5 |
83.33% |
14 |
5 |
35.71% |
7 |
3 |
42.85% |
|
cefoperazone/salbactum |
6 |
4 |
66.67% |
11 |
6 |
54.54% |
6 |
2 |
33.30% |
|
doxycyclin |
6 |
4 |
66.67% |
9 |
3 |
33.33% |
9 |
3 |
33.30% |
|
linezolide |
8 |
3 |
37.50% |
16 |
10 |
62.50% |
9 |
7 |
77.77% |
|
piptaz |
6 |
4 |
66.67% |
16 |
7 |
43.75% |
7 |
2 |
28.57% |
|
ciprofloxacin |
7 |
2 |
28.57% |
11 |
5 |
45.45% |
7 |
6 |
85.71% |
|
co-trimoxazole |
7 |
3 |
42.85% |
12 |
5 |
41.66% |
5 |
2 |
40% |
|
meropenam |
8 |
4 |
50% |
9 |
5 |
55.50% |
11 |
6 |
54.54% |
|
amikacin |
6 |
3 |
50% |
12 |
6 |
50% |
12 |
6 |
50% |
|
gentamicin |
7 |
2 |
28.57% |
12 |
9 |
75% |
8 |
6 |
75% |
|
penicillin |
6 |
6 |
100% |
7 |
5 |
71.42% |
8 |
3 |
37.50% |
DISCUSSION
In this prospective observational study, antibiotic utilization patterns and resistance trends were analyzed among inpatients who underwent culture sensitivity testing. Males constituted a higher proportion (57.42%) than females (42.58%), which aligns with previous reports showing male predominance in hospital admissions and antibiotic use. Elderly patients, particularly those aged 60–70 years, formed the majority, reflecting their increased vulnerability to infections due to age-related immune decline and frequent comorbidities. Empirical antibiotic therapy was initially dominated by third-generation cephalosporins (82.7%). Following culture sensitivity results, their usage significantly declined (30.5%), and monotherapy was increasingly favored, demonstrating a positive shift towards rational, pathogen-directed treatment. This transition supports antimicrobial stewardship principles and aligns with best practices aimed at reducing antimicrobial resistance?. Specimen-wise, pus, sputum, and urine were the most common sources, with culture revealing diverse bacterial isolates. These findings are consistent with global patterns of nosocomial infections, particularly in wound, respiratory, and urinary tract sites?. The presence of multidrug-resistant organisms across both Gram-negative and Gram-positive groups suggests widespread selection pressure, likely driven by empirical overuse and delayed de-escalation strategies¹?. Comorbidities such as diabetes mellitus, anemia, and chronic kidney disease were commonly observed among the study population. These conditions are known to impair immunity and prolong hospital stays, increasing the risk of healthcare-associated infections and antimicrobial resistance¹¹. Furthermore, the presence of such comorbidities often prompts the use of broad-spectrum antibiotics empirically, which may accelerate the development of resistance when not properly guided by microbiological evidence¹². The study has several limitations. It was conducted over a limited period of six months and was restricted to patients from the General Medicine and General Surgery departments. As a result, seasonal trends and ward-specific variations in infection rates and resistance patterns could not be assessed. Additionally, the study did not include molecular characterization of resistance genes, which would have provided further insight into the underlying mechanisms and transmission of resistance determinants¹³. Despite these limitations, the study contributes meaningful data to the growing body of antimicrobial resistance (AMR) surveillance in India. It reinforces the value of timely culture testing and the importance of shifting from empirical to targeted therapy. The findings also underscore the critical need for hospital-wide infection control policies and antimicrobial stewardship programs. Establishing dedicated stewardship teams, promoting the rational use of antimicrobials, and providing continuous education to healthcare providers are essential steps to reduce irrational prescribing and preserve the efficacy of existing antibiotics¹?.
CONCLUSION
This study emphasizes the importance of rational antibiotic use and timely culture-based decision-making in clinical practice. A positive shift was observed from empirical to targeted therapy, improving treatment accuracy and reducing unnecessary drug exposure. The use of standardized methods and ethical compliance added strength to the findings. The results support the need for continued monitoring, effective stewardship, and personalized patient care to control resistance and enhance therapeutic outcomes.
Conflict of interest
The authors declare no conflict of interest. All authors have reviewed and approved the final manuscript.
ACKNOWLEDGEMENT
The authors express their sincere gratitude to the Departments of General Surgery, General Medicine, and Microbiology at Government Medical College Hospital, Nagapattinam, for their continuous support throughout the study. We are also grateful to the patients who voluntarily participated. Special appreciation is extended to Dr. B. Sarathbabu, our project guide, for his invaluable guidance and encouragement during the research.
REFERENCES
Dr. B. Sarathbabu, A. Jeeva*, R. Kanchana, M. Padhma, Comprehensive Antibiotic Drug Resistance Surveillance and Antibiotic Utilisation Review: A Prospective Observational Study, Int. J. of Pharm. Sci., 2025, Vol 3, Issue 8, 1761-1768. https://doi.org/10.5281/zenodo.16885273
10.5281/zenodo.16885273
