PATTERNS OF ANTIMICROBIAL USE, THEIR ADVERSE EFFECTS AND COST ANALYSIS IN THE CCU OF A TERTIARY CARE TEACHING HOSPITAL IN EASTERN INDIA: AN OBSERVATIONAL STUDY

Table 1: Sociodemographic Characteristics of Study Participants (n = 196)

The majority of study participants belonged to the age group 51–60 years (24.5%), followed closely by 61–70 years (22.4%). Nearly half of the patients (46.9%) were between 51–70 years of age. The age distribution was statistically significant (p = 0.021). A significant male predominance was observed, with 63.3% males and 36.7% females (p = 0.004). Most patients were from rural areas (60.2%) compared to urban areas (39.8%), which was also statistically significant (p = 0.018).

Table 1: Sociodemographic Characteristics of Study Participants (n = 196)

Table 2: Clinical Profile and Comorbidities of Study Participants (n = 196)

Table 3: Clinical Presentation and Hospital Stay (n = 196)

Table 4: Microbiological Profile (n = 196)

Table 5: Organism-wise Distribution (n = 96 culture-positive cases)

Table 6: Antibiotic Sensitivity Pattern and Prescribing Pattern (n = 196)

Table 7: Adverse Drug Reactions and Cost Analysis (n = 196)

(a)    Adverse Drug Reactions

(b)   Cost Analysis

Figure: 1. Clinical Profile and Comorbidities of Study Participants

Figure: 2. Antibiotic Sensitivity Pattern and Prescribing Pattern

Table 2: Clinical Profile and Comorbidities of Study Participants (n = 196)

Sepsis/septic shock (27.6%) was the most common provisional diagnosis at CCU admission, followed by pneumonia (21.4%). Together, these two conditions accounted for nearly half of the admissions requiring antimicrobial therapy. The distribution of provisional diagnoses was statistically significant (p = 0.001).

Among comorbidities, diabetes mellitus (31.6%) was most prevalent, followed by hypertension (28.6%). A notable proportion (19.4%) had no known comorbidity. The distribution of comorbid conditions showed statistical significance (p = 0.032).

Table 3: Clinical Presentation and Hospital Stay (n = 196)

Fever (75.5%) was the most common presenting symptom, followed by breathlessness (67.3%) and tachycardia (60.2%). These findings were statistically significant (p < 0.001 and p = 0.022 respectively). Respiratory manifestations such as cough with expectoration (49.0%) and oxygen requirement (53.1%) were also common.

Regarding duration of hospital stay, most patients (37.8%) stayed for 6–10 days, while 24.5% stayed for 11–15 days. Overall, 62.3% had a hospital stay between 6–15 days. The association between duration categories was statistically significant (p = 0.015).

Table 4: Microbiological Profile (n = 196)

Culture specimens were sent in 83.7% of patients, which was statistically significant (p < 0.001). Among them, 49.0% were culture positive, while 34.7% were culture negative. Multidrug-resistant (MDR) organisms were isolated in 19.4% of cases, which showed statistical significance (p = 0.009). This highlights a considerable burden of resistant infections in the CCU setting.

Table 5: Organism-wise Distribution (n = 96 culture-positive cases)

Among culture-positive isolates, Klebsiella pneumoniae (27.1%) was the most common pathogen, followed by Escherichia coli (22.9%) and Acinetobacter baumannii (16.7%). Gram-negative organisms predominated overall. The distribution of organisms was statistically significant (p = 0.003), indicating a higher prevalence of certain pathogens in CCU infections.

Table 6: Antibiotic Sensitivity Pattern and Prescribing Pattern (n = 196)

High resistance rates were observed for third-generation cephalosporins such as ceftriaxone (56.2%) and cefepime (52.1%), which were statistically significant. In contrast, carbapenems (meropenem 75.0%, imipenem 72.9%) and colistin (91.7%) retained high sensitivity (p < 0.001). For Gram-positive isolates, vancomycin and linezolid demonstrated excellent sensitivity (88.9% and 94.4% respectively).

These findings indicate significant antimicrobial resistance, particularly against commonly used cephalosporins, necessitating rational antibiotic use in CCU practice.

Table 7: Adverse Drug Reactions and Cost Analysis (n = 196)

Adverse drug reactions (ADRs) were observed in 28.6% of patients. Gastrointestinal upset (9.2%) was the most common ADR, followed by nephrotoxicity (7.1%) and hepatotoxicity (5.1%). The association was statistically significant (p = 0.031).

Regarding cost analysis, the majority of patients (34.7%) incurred a daily antimicrobial cost between ₹500–1000 (p = 0.022). For total antimicrobial expenditure during CCU stay, 32.7% spent between ₹5001–10,000, while 19.4% incurred costs exceeding ₹20,000 (p = 0.017). Higher costs were associated with prolonged hospitalization and use of reserve antibiotics such as carbapenems and colistin.

The present cross-sectional observational study evaluated antimicrobial utilization, microbiological profile, resistance pattern, adverse drug reactions, and cost implications among CCU patients. The majority of patients in our study belonged to the age group 51–70 years (46.9%), which is consistent with findings reported by Patel et al. [11], who observed that elderly patients constituted the largest proportion of critically ill individuals requiring antimicrobial therapy. Similar age predominance was also reported by Singh et al. [12], highlighting increased susceptibility to infections due to immunosenescence and multiple comorbidities in older adults.

A significant male predominance (63.3%) was observed in our study, comparable to the findings of Sharma et al. [13], who reported 61% male admissions in their ICU antimicrobial utilization study. This may be attributed to higher prevalence of risk factors such as smoking, occupational exposure, and delayed healthcare-seeking behavior among males in the Indian setting. Rural predominance (60.2%) in our study aligns with the findings of Das et al. [14], who documented increased referrals from rural areas to tertiary care centers, reflecting disparities in primary healthcare infrastructure.

Sepsis and pneumonia together accounted for nearly half of CCU admissions in the present study. Similar trends were reported by Vincent et al. [15] in the EPIC II study, where respiratory infections were the leading cause of ICU infections globally. An Indian multicentric study by Chatterjee et al. [16] also identified sepsis as the most common indication for broad-spectrum antimicrobial use in critical care units.

Diabetes mellitus was the most frequent comorbidity (31.6%) in our cohort. This finding corroborates observations by Mohanty et al. [17], who reported diabetes as a significant risk factor for severe infections and prolonged antimicrobial therapy in ICU settings. Hyperglycemia impairs neutrophil function and cellular immunity, predisposing to complicated infections.

Regarding microbiological profile, culture positivity was 49%, comparable to findings by Gupta et al. [18], who reported 45–52% culture positivity in ICU patients. Gram-negative organisms predominated in our study, with Klebsiella pneumoniae and Escherichia coli being the most common isolates. Similar organism distribution was noted in the ICMR Antimicrobial Resistance Surveillance Report [19], which documented Gram-negative bacilli as predominant ICU pathogens across India.

A concerning finding was the high prevalence of multidrug-resistant (MDR) organisms (19.4%). This is in line with the study by Tiwari et al. [20], who reported MDR rates ranging from 18–25% in tertiary care ICUs. Resistance to third-generation cephalosporins observed in our study mirrors national resistance trends, likely due to overuse and empirical prescribing practices. However, carbapenems and colistin retained relatively good sensitivity, similar to observations by Gupta et al. [18]. The preserved sensitivity of vancomycin and linezolid for Gram-positive isolates is also consistent with prior ICU-based antimicrobial surveillance studies [13].

Empirical antimicrobial therapy was initiated in 65.3% of patients in our study, comparable to the 60–70% empirical initiation rate reported by Singh et al. [12]. This reflects the urgency of treatment in critically ill patients, although it underscores the need for timely de-escalation based on culture results to prevent resistance development.

Adverse drug reactions were observed in 28.6% of patients, with nephrotoxicity being clinically significant. Similar findings were reported by Sharma et al. [13], where nephrotoxicity was primarily associated with aminoglycosides and colistin use. This emphasizes the importance of renal function monitoring during antimicrobial therapy in CCU patients.

Cost analysis in the present study revealed substantial expenditure, particularly in patients receiving reserve antibiotics and prolonged therapy. Comparable economic burdens were documented by Mohanty et al. [17], who reported significantly higher antimicrobial costs in patients with MDR infections and extended ICU stay.

Overall, the findings of the present study align with national and international literature, highlighting the predominance of Gram-negative infections, significant antimicrobial resistance, high empirical antibiotic use, and considerable economic burden in CCU settings. These findings reinforce the urgent need for antimicrobial stewardship programs, routine antibiogram surveillance, and rational prescribing strategies to combat the growing threat of antimicrobial resistance.

The present study demonstrated a high burden of infectious diseases requiring antimicrobial therapy among CCU patients, with sepsis and pneumonia being the leading indications. Gram-negative organisms, particularly Klebsiella pneumoniae and Escherichia coli, predominated, and a considerable proportion of multidrug-resistant isolates was observed. Significant resistance to third-generation cephalosporins was noted, while carbapenems and colistin retained comparatively better sensitivity. Empirical antimicrobial therapy was initiated in the majority of cases, reflecting the urgency of critical care management. Adverse drug reactions were observed in nearly one-third of patients, with nephrotoxicity being clinically important. Additionally, substantial antimicrobial-related expenditure was documented, especially among patients requiring prolonged CCU stay and reserve antibiotics.Overall, the findings emphasize the urgent need for strengthened antimicrobial stewardship programs, regular antibiogram surveillance, rational prescribing practices, and continuous monitoring of drug safety to optimize therapeutic outcomes and reduce antimicrobial resistance in critical care settings.