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Complex typing of Pseudomonas aeruginosa strains isolated in an intensive care unit [a note]
I Barcs1, L Jánosi, A Szentmihályi
1National Institute of Hygiene, Budapest, Hungary.
Abstract:
A total of 2637 Gram-negative facultatively pathogenic bacteria were isolated in the László Central Hospital for Infectious Diseases during a 5-year-period from clinical samples of patients of the Respiratory Intensive Care Unit; 28 further strains were cultured from hospital personnel and fomites. Pseudomonas aeruginosa, Klebsiella and Acinetobacter spp. were most frequently isolated. Complex typing (determination of O serogroup, phage pattern, pyocin type, antibiogram and plasmid pattern) of P. aeruginosa strains showed the predominance of serogroup O11 (62%), but the isolates differed from each other by other characteristics. Conjugation experiments showed no common resistance plasmids in the tested population.
Insights
This 5-year study identified 2637 Gram-negative bacteria in a hospital, with Pseudomonas aeruginosa, Klebsiella, and Acinetobacter being most common. Most P. aeruginosa strains belonged to serogroup O11, but showed diverse characteristics, with no shared resistance plasmids found.
Area of Science:
- Clinical Microbiology
- Infectious Diseases
- Bacterial Pathogenesis
Background:
- Gram-negative bacteria pose significant threats in healthcare settings.
- Pseudomonas aeruginosa, Klebsiella, and Acinetobacter are common nosocomial pathogens.
- Understanding bacterial epidemiology is crucial for infection control.
Purpose of the Study:
- To characterize Gram-negative bacteria isolated from a hospital over five years.
- To identify the predominant species and serotypes of Pseudomonas aeruginosa.
- To investigate potential plasmid-mediated resistance among isolates.
Main Methods:
- Isolation and identification of Gram-negative bacteria from clinical samples, personnel, and fomites.
- Comprehensive typing of Pseudomonas aeruginosa strains, including O serogroup, phage typing, pyocin typing, antibiogram, and plasmid profiling.
- Conjugation experiments to assess plasmid-mediated resistance transfer.
Main Results:
- 2637 Gram-negative facultatively pathogenic bacteria were isolated over 5 years.
- Pseudomonas aeruginosa, Klebsiella, and Acinetobacter spp. were the most frequently isolated.
- Serogroup O11 predominated (62%) among P. aeruginosa, but isolates showed heterogeneity in other typing characteristics.
- No common resistance plasmids were detected in the tested P. aeruginosa population.
Conclusions:
- The study highlights the prevalence of specific Gram-negative bacteria in a hospital setting.
- Pseudomonas aeruginosa serogroup O11 is common, but genetic diversity exists within this group.
- The absence of common resistance plasmids suggests other mechanisms for resistance or limited horizontal gene transfer in this cohort.