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Typing of Pseudomonas cepacia by bacteriocin susceptibility and production
Abstract:
The significance of Pseudomonas cepacia as an opportunistic pathogen in immunocompromised patients has become increasingly recognized. Particularly disturbing is its increased incidence, reported by several North American centers, in respiratory tract cultures from patients with cystic fibrosis. Epidemiological studies of P. cepacia have been hampered by a lack of typing methods. In this paper we report the development of a typing scheme based on bacteriocin production and susceptibility. For bacteriocin production, test isolates of P. cepacia were rapidly applied to the surfaces of agar plates with a multiple inoculator. After incubation of these test isolates for 5.5 h and their exposure to chloroform, indicator strains were applied in agar overlays without prior removal of the test strain growth. After 18 h of incubation, inhibition zones caused by bacteriocin activity were recognized. A similar procedure was used to examine the bacteriocin susceptibility of the test strain. The bacteriocin type of the test strain was defined based on its bacteriocin production as judged by zones of inhibition against a set of eight indicator strains and by susceptibility or resistance of the test strain to bacteriocin produced by six producer strains. Of 373 strains of P. cepacia, 95.2% were typed into a total of 44 type combinations. Bacteriocin typing provided a suitable procedure for epidemiological studies of colonization or infection by P. cepacia. The technique described in this paper was simple to perform, gave a result within 24 h, provided good strain discrimination, and was suitable for clinical, environmental, and phytopathogenic strains.
Insights
A new bacteriocin typing method effectively identifies Pseudomonas cepacia strains, crucial for tracking this opportunistic pathogen in cystic fibrosis patients and immunocompromised individuals. This rapid technique aids in epidemiological studies.
Area of Science:
- Microbiology
- Epidemiology
- Bacteriology
Background:
- Pseudomonas cepacia is an opportunistic pathogen increasingly recognized in immunocompromised patients.
- A rise in P. cepacia incidence in cystic fibrosis patients necessitates improved epidemiological tracking.
- Current P. cepacia typing methods are insufficient for effective epidemiological studies.
Purpose of the Study:
- To develop and validate a novel bacteriocin-based typing scheme for Pseudomonas cepacia.
- To establish a reliable method for differentiating P. cepacia strains for epidemiological purposes.
Main Methods:
- Bacteriocin production and susceptibility testing were performed on P. cepacia isolates.
- Isolates were applied to agar plates, exposed to chloroform, and overlaid with indicator strains.
- Strain typing was based on inhibition zones and susceptibility to known bacteriocins.
Main Results:
- The developed bacteriocin typing scheme successfully typed 95.2% of 373 P. cepacia strains into 44 distinct combinations.
- The method demonstrated good strain discrimination and was applicable to clinical, environmental, and phytopathogenic strains.
- Typing results were obtained within 24 hours, indicating a rapid and efficient procedure.
Conclusions:
- Bacteriocin typing is a simple, rapid, and effective method for the epidemiological study of Pseudomonas cepacia.
- This technique provides essential strain discrimination for understanding P. cepacia colonization and infection patterns.
- The method's versatility makes it suitable for diverse P. cepacia strain types and sources.