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Characterization of Bacillus thuringiensis isolated from infections in burn wounds
P H Damgaard1, P E Granum, J Bresciani
1Department of Ecology and Molecular Biology, The Royal Veterinary and Agricultural University, Frederiksberg C, Denmark.
Abstract:
Four strains of Bacillus thuringiensis were isolated from infections in burn wounds and from water used in the treatment of burn wounds. The strains produced large parasporal inclusion bodies composed of 141, 83, and 81 kDa protoxins. The four strains were tested for insecticidal activity against larvae of Pieris brassicae and Aedes aegypti but showed no activity; Vero cell assays for the production of enterotoxins were also negative. Attempts to classify the strains according to flagellar H-serotype showed them all to be non-flagellated. Apart from two occupational health accidents that occurred during the handling of highly concentrated B. thuringiensis fluids, this is the first report of B. thuringiensis causing non-gastrointestinal clinical infection in immunosuppressed patients.
Insights
This study reports the first instance of Bacillus thuringiensis (B. thuringiensis) causing non-gastrointestinal infections in immunosuppressed patients. The isolated strains, found in burn wound infections, lacked insecticidal and enterotoxin activity and were non-flagellated.
Area of Science:
- Microbiology
- Clinical Medicine
- Toxicology
Background:
- Bacillus thuringiensis (B. thuringiensis) is a soil bacterium.
- It is known for producing insecticidal toxins and parasporal inclusion bodies.
- B. thuringiensis is widely used as a biological pesticide.
Purpose of the Study:
- To characterize four strains of B. thuringiensis isolated from clinical specimens.
- To investigate their potential for insecticidal and enterotoxic activity.
- To report the first case of B. thuringiensis causing non-gastrointestinal infections in humans.
Main Methods:
- Isolation of B. thuringiensis from burn wound infections and associated water.
- Analysis of parasporal inclusion bodies and protoxin composition (141, 83, 81 kDa).
- Testing for insecticidal activity against Pieris brassicae and Aedes aegypti larvae.
- Vero cell assays for enterotoxin production.
- Flagellar H-serotype classification (non-flagellated strains identified).
Main Results:
- Four B. thuringiensis strains were isolated from burn wound infections and treatment water.
- The strains produced large parasporal inclusion bodies with protoxins of 141, 83, and 81 kDa.
- No insecticidal activity was observed against tested larvae.
- Enterotoxin production was negative in Vero cell assays.
- All four strains were non-flagellated, preventing H-serotype classification.
- Two occupational health incidents occurred during handling of concentrated bacterial fluids.
Conclusions:
- The isolated B. thuringiensis strains possess insecticidal protoxins but lack demonstrable insecticidal or enterotoxic activity.
- The non-flagellated nature of these strains is unusual.
- This study presents the first documented cases of B. thuringiensis causing non-gastrointestinal clinical infections, specifically in immunosuppressed patients, highlighting a potential occupational hazard.