Clinically Isolated β-Lactam-Resistant Gram-Negative Bacilli in a Philippine Tertiary Care Hospital Harbor...

Area of Science:

• Microbiology
• Infectious Diseases
• Antimicrobial Resistance

Background:

• Data on co-occurring beta-lactamases (BLs) in clinical Gram-negative bacilli in the Philippines is limited.
• Understanding the genetic basis of resistance is crucial for effective treatment strategies.
• The rise of multidrug-resistant organisms poses a significant global health threat.

Purpose of the Study:

• To characterize the co-occurrence of multiple beta-lactamases (BLs) in clinically isolated Gram-negative bacilli in the Philippines.
• To identify specific beta-lactamase genes conferring resistance to various antibiotic classes.
• To provide genotypic and phenotypic data on beta-lactam resistance mechanisms in key pathogens.

Main Methods:

• Antibiotic susceptibility testing was performed on 29 Gram-negative bacilli isolates (Klebsiella pneumoniae, Escherichia coli, Acinetobacter baumannii, Pseudomonas aeruginosa).
• Disk-diffusion-based beta-lactamase detection assays were employed.
• Polymerase chain reaction (PCR) and sequence analysis were used to identify genes for extended-spectrum BLs (ESBLs), metallo-BLs (MBLs), AmpC BLs, and oxacillinases.

Main Results:

• Twenty-six out of 29 isolates harbored multi-class BLs.
• blaCTX-M was the dominant ESBL gene (19/29).
• Metallo-beta-lactamase genes (blaNDM, blaIMP) were identified in carbapenem-resistant isolates, and blaOXA-24-like genes were found in other resistant categories.

Conclusions:

• The study revealed a high prevalence of multi-class beta-lactamases among Gram-negative bacilli in a Philippine hospital.
• Genotypic profiling identified diverse resistance mechanisms, including ESBLs, MBLs, and oxacillinases.
• These findings underscore the urgent need for enhanced surveillance and antimicrobial stewardship programs to combat rising resistance.