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. 2011 Sep;77(18):6729-32.
doi: 10.1128/AEM.05226-11. Epub 2011 Jul 29.

Use of acid treatment and a selective medium to enhance the recovery of Francisella tularensis from water

B W Humrighouse  1 , N J Adcock, E W Rice
Affiliations

Use of acid treatment and a selective medium to enhance the recovery of Francisella tularensis from water

B W Humrighouse et al. Appl Environ Microbiol. 2011 Sep.

Abstract

Francisella tularensis has been associated with naturally occurring waterborne outbreaks and is also of interest as a potential biological weapon. Recovery of this pathogen from water using cultural methods is challenging due to the organism's fastidious growth requirements and interference by indigenous bacteria. A 15-min acid treatment procedure prior to culture on a selective agar was evaluated for recovery of F. tularensis from seeded water samples. Mean levels of reduction of virulent strains of F. tularensis subsp. holarctica and subsp. tularensis were less than 20% following acid treatment. The attenuated live vaccine strain (LVS) was less resistant to acid exposure. The acid treatment procedure coupled with plating on cystine heart agar with rabbit blood and antibiotics (CHARBab) allowed the isolation of F. tularensis seeded into five natural water samples.

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Figures

Fig. 1.
Fig. 1.
Effect of acid treatment on F. tularensis strains seeded into sterile chlorine-free tap water. Shown are untreated samples (black) and acid-treated samples (gray). Error bars indicate standard deviations for each replicate.
Fig. 2.
Fig. 2.
The effect of acid treatment on F. tularensis subsp. holarctica strains recovered from five seeded natural water samples. Shown are untreated samples (black) and acid-treated samples (gray). Error bars indicate standard deviations for each replicate.
See this image and copyright information in PMC

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