Spectrum of Bacterial Isolates and Their Antimicrobial Susceptibility Pattern in a Pediatric Intensive Care Unit: A Prospective Observational Study.

Healthcare-associated infections remain a major challenge in pediatric intensive care units, contributing significantly to morbidity and mortality.[1,2] Children admitted to PICUs are particularly vulnerable due to invasive procedures, prolonged hospitalization, and frequent exposure to broad-spectrum antibiotics.

 

Antimicrobial resistance has emerged as a critical global health concern, limiting therapeutic options and increasing healthcare burden.[3] Empirical antibiotic therapy is often initiated in critically ill children; however, inappropriate use may promote resistance.[4]

 

Studies from developing countries have consistently demonstrated that Gram-negative organisms are the predominant pathogens in intensive care settings.[5,6] Organisms such as Klebsiella, Acinetobacter, and Pseudomonas are known for their ability to acquire multiple resistance mechanisms, including extended-spectrum beta-lactamase and carbapenemase production.[7]

 

Regular monitoring of bacterial isolates and their antimicrobial susceptibility patterns is essential for guiding empirical therapy and strengthening antibiotic stewardship programs.[8] This study was conducted to evaluate the bacterial spectrum and antibiogram pattern in a tertiary care PICU.

This prospective observational study was conducted in the pediatric intensive care unit of NRI Institute of Medical Sciences, Visakhapatnam, from June 2024 to June 2025.

Children aged 1 month to 18 years with suspected bacterial infections were included. Patients with contaminated samples and duplicate isolates were excluded.

 

Clinical specimens including blood, urine, cerebrospinal fluid, endotracheal aspirate, pus, and pleural fluid were collected aseptically and processed using standard microbiological methods. Identification of organisms was performed by conventional techniques. Antimicrobial susceptibility testing was carried out using the Kirby–Bauer disk diffusion method and interpreted according to CLSI guidelines.[9] Multidrug resistance was defined as resistance to at least one agent in three or more antimicrobial classes.[10]

 

Statistical Analysis

Data were analyzed using descriptive statistics. Categorical variables were expressed as percentages, while continuous variables were presented as mean ± standard deviation.

A total of 254 children were admitted during the study period, of whom 124 (48.8%) had culture-positive infections.

The mean age was 4.2 ± 3.6 years, with a male predominance (58.5%). Mechanical ventilation was required in 52% of cases.

 

Gram-negative organisms constituted 82.1% of isolates. The most frequently identified pathogens were Klebsiella pneumoniae, followed by Acinetobacter baumannii, Escherichia coli, and Pseudomonas aeruginosa. Among Gram-positive organisms, Staphylococcus aureus was the most common. Endotracheal aspirates showed the highest positivity rate, suggesting a significant burden of ventilator-associated infections.[2]

 

A high level of resistance was observed to third-generation cephalosporins and fluoroquinolones. Carbapenems demonstrated moderate sensitivity, while colistin retained high activity against multidrug-resistant organisms.[7,11]

Gram-positive organisms showed preserved susceptibility to vancomycin and linezolid.[12].

The present study highlights the predominance of Gram-negative bacterial infections in the PICU, which is consistent with previous reports from similar healthcare settings.[5,6]

 

Klebsiella pneumoniae and Acinetobacter baumannii were the leading pathogens identified. These organisms are commonly associated with hospital-acquired infections, particularly in ventilated patients, and have the ability to survive in hospital environments.[2,7]

 

The high resistance to cephalosporins observed in this study suggests the presence of extended-spectrum beta-lactamase-producing organisms, a trend also reported in national surveillance data.[3]

 

Although carbapenems remain an important treatment option, emerging resistance among Gram-negative organisms is concerning and limits therapeutic choices. Rational use of these agents is essential to prevent further resistance.

Colistin demonstrated high effectiveness against multidrug-resistant organisms, consistent with earlier studies.[11] However, its potential toxicity necessitates cautious use.

 

Gram-positive isolates retained good sensitivity to vancomycin and linezolid, which aligns with previous findings.[12]

Continuous monitoring of antimicrobial resistance patterns, along with strict infection control measures and antibiotic stewardship programs, is crucial in reducing the burden of resistant infections.[8].

Gram-negative organisms are the predominant pathogens in PICU infections and exhibit significant resistance to commonly used antibiotics. Regular surveillance and appropriate antibiotic policies are essential to improve patient outcomes and combat antimicrobial resistance.

 

Table 1: Distribution of Culture Positivity

 

Table 2: Clinical Characteristics

 

Table 3: Bacterial Isolates

 

Table 4 Antibiotic susceptibility pattern (% sensitive)

Gram-negative organisms

Gram-positive organisms

 

 

WHAT THIS STUDY ADDS

▪ Provides updated PICU antibiogram data from an Indian tertiary care center

▪ Highlights the growing burden of multidrug-resistant Gram-negative infections

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2.       Richards MJ, Edwards JR, Culver DH. Nosocomial infections in pediatric intensive care units. Crit Care Med. 1999;27:887-92.

3.       Laxminarayan R, Sridhar D, Blaser M. Antimicrobial resistance: a global priority. Lancet Infect Dis. 2016;16:412-13.

4.       Weiss SL, Peters MJ, Alhazzani W, et al. Surviving sepsis campaign guidelines. Intensive Care Med. 2020;46:S10-S67.

5.       DeNIS Study Group. Burden of antibiotic resistance in India. Lancet Glob Health. 2016;4:e752-e760.

6.       ICMR Antimicrobial Resistance Surveillance Network. Annual report 2023.

7.       Paterson DL. Resistance in Gram-negative bacteria. Clin Infect Dis. 2006;43:S43-S48.

8.       Dellit TH, Owens RC. Antimicrobial stewardship principles. Clin Infect Dis. 2007;44:159-77.

9.       Clinical and Laboratory Standards Institute. CLSI M100. 2023.

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11.    Falagas ME. Colistin use in MDR infections. Clin Infect Dis. 2005;40:1333-41.

12.    Chambers HF. MRSA epidemiology. Clin Microbiol Rev. 2001;14:1-22.