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Potential pathogens in the environment: Klebsiella pneumoniae, a taxonomic and ecological enigma
Abstract:
A nitrogen-deficient medium and m-Endo agar were employed in the isolation of members of the tribe Klebsielleae from surfaces of vegetables and seeds. With m-Endo agar at an incubation temperature of 37 C, nearly 50% of the vegetables and seven out of seven seed samples yielded organisms which biochemically and serologically were identified as Klebsiella pneumoniae, Viable counts were generally in the range of 10(3) cells per g of vegetable peel or seed. Organisms classified as K. pneumoniae exhibited seven different IMViC patterns, with the --++, ++++, and -+++ patterns most common. Seven of the eleven K. pneumoniae serotypes encountered have previously been isolated from human urinary tract and other infections. Fifty percent of the 40 K. pneumoniae examined exhibited positive acetylene-reducing activity, i.e., they possessed the capability for fixing N(2). Vegetables containing K. pneumoniae may constitute a potential reservoir for human nosocomial genitourinary or other infections.
Insights
Klebsiella pneumoniae was isolated from vegetables and seeds using m-Endo agar. This common bacterium, found on produce, can fix nitrogen and poses a potential infection risk to humans.
Area of Science:
- Microbiology
- Food Safety
- Environmental Science
Background:
- Klebsiella pneumoniae is an opportunistic pathogen.
- The presence of K. pneumoniae on produce is not well-documented.
- Understanding reservoirs of K. pneumoniae is crucial for public health.
Purpose of the Study:
- To isolate and identify Klebsiella species from vegetable and seed surfaces.
- To determine the prevalence of Klebsiella pneumoniae on produce.
- To assess the potential of produce as a reservoir for K. pneumoniae.
Main Methods:
- Nitrogen-deficient medium and m-Endo agar were used for isolation.
- Incubation was performed at 37°C.
- Biochemical and serological methods identified isolates as K. pneumoniae.
Main Results:
- Nearly 50% of vegetables and 100% of seed samples yielded K. pneumoniae.
- Viable counts ranged from 10^3 cells/g.
- K. pneumoniae isolates showed seven IMViC patterns, with --++, ++++, and -+++ being most common.
- Fifty percent of isolates exhibited acetylene-reducing activity (nitrogen fixation).
- Seven of eleven K. pneumoniae serotypes were previously linked to human infections.
Conclusions:
- Vegetables and seeds can harbor Klebsiella pneumoniae.
- K. pneumoniae on produce may represent a reservoir for human infections, particularly nosocomial ones.
- The nitrogen-fixing capability of these isolates warrants further investigation.