Antibiotic Usage Pattern and Consumption Metrics in Hospitalized Patients with Community-Acquired Pneumonia: An Observational Study from a Tertiary Care Centre in South India

ntroduction: Community-acquired pneumonia (CAP) remains one of the leading causes of hospitalization and mortality globally. Empirical antibiotic use varies regionally, and data from India are limited. Evaluating antibiotic usage and consumption metrics such as Defined Daily Dose (DDD) and Antibiotic Consumption Index (ACI) helps in antibiotic stewardship and optimizing treatment outcomes.

Objectives: To assess the antibiotic usage pattern, microbiological profile, hospital stay characteristics, and consumption indices (DDD and ACI) among hospitalized patients with community-acquired pneumonia in a tertiary care setting.

Methodology: A six-month prospective observational study was conducted at Victoria Hospital, BMCRI, Bengaluru from August 2023 to January 2024. A total of 124 hospitalized CAP patients were included. Data on demographics, antibiotic use, culture results, comorbidities, duration of hospital stay, and outcomes were analyzed. Antibiotic consumption was quantified using WHO ATC/DDD methodology and expressed as DDD/100 bed-days and ACI (DDD/patient).

Results: Among 124 patients, 84 (67.7%) were males, and 40 (32.3%) were females. 104 (83.9%) were direct admissions, and 20 (16.1%) were referred.

Prior antibiotic use (>5 times/year) was noted in 24 (19.4%), and 36 (29%) had over-the-counter (OTC) antibiotic exposure,40(32%) patients had not taken any Antibiotic.

Comorbidities were present in 38 patients (30.6%): diabetes (10), hypertension (12), COPD (16), asthma (2), hypothyroidism (2), cerebrovascular accident (4), and ischemic heart disease (6).

Patients with ≥3 comorbidities (8/124, 6.5%) had significantly higher mortality.

Sputum culture was sent for all 124 patients and positivity was 58.06% (72/124)

blood cultures were positive in 18/64 (28.1%)

The most common organism was Streptococcus pneumoniae (44.4%), followed by Staphylococcus aureus (25%), Klebsiella pneumoniae (8.3%), Pseudomonas aeruginosa (6.9%), E. coli (6.9%), Acinetobacter (2.8%), and H. influenzae (2.8%).

Empirical antibiotics: Ceftriaxone was most common (72), followed by Azithromycin (24) and Amoxiclav (18). Single-drug therapy was used in 91 (73.4%), dual in 22 (17.7%), and triple in 11 (8.9%). Antibiotic modification post-culture occurred in 44 (35.5%).

Duration of stay

Place of stay:

Mortality: 8 (6.45%) — mainly elderly (>70 years), with multiple comorbidities and prior antibiotic abuse. Culture-negative patients (n=52) had higher rates of prolonged stay (12/52), ICU admission (6/52), and death (5/52).

Antibiotic Consumption: The total antibiotic use was 1204 DDDs over 868 bed-days, giving 139 DDD/100 bed-days and an ACI of 9.7 DDDs/patient.

Ceftriaxone accounted for the highest consumption (58.1 DDD/100 bed-days), followed by Azithromycin (19.4) and Amoxiclav (14.5).

Conclusion: Ceftriaxone-based empirical therapy predominates in CAP management at our centre. High rates of OTC and repeated antibiotic use were observed. S. pneumoniae remains the leading pathogen, but Gram-negative organisms are emerging. Elevated antibiotic consumption indices emphasize the need for stewardship programs. Culture-based modification and regular local antibiogram updates are essential to optimize outcomes and curb resistance.