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Spores of Clostridium difficile clinical isolates display a diverse germination response to bile salts.

Heeg D, Burns DA, Cartman ST, Minton NP - PLoS ONE (2012)

Bottom Line: Strikingly, we also show that although a potent inhibitor of germination for some isolates, chenodeoxycholate does not inhibit the germination, or outgrowth, of all C. difficile strains.Finally, we provide evidence that components of rich media may induce the germination of C. difficile spores, even in the absence of taurocholate.Furthermore, we stress the importance of studying multiple isolates in the future when analysing the nutrients or chemicals that either stimulate or inhibit C. difficile spore germination.

View Article: PubMed Central - PubMed

Affiliation: Clostridia Research Group, School of Molecular Medical Sciences, Centre for Biomolecular Sciences, University of Nottingham, Nottingham, United Kingdom.

ABSTRACT
Clostridium difficile spores play a pivotal role in the transmission of infectious diarrhoea, but in order to cause disease spores must complete germination and return to vegetative cell growth. While the mechanisms of spore germination are well understood in Bacillus, knowledge of C. difficile germination remains limited. Previous studies have shown that bile salts and amino acids play an important role in regulating the germination response of C. difficile spores. Taurocholate, in combination with glycine, can stimulate germination, whereas chenodeoxycholate has been shown to inhibit spore germination in a C. difficile clinical isolate. Our recent studies of C. difficile sporulation characteristics have since pointed to substantial diversity among different clinical isolates. Consequently, in this study we investigated how the germination characteristics of different C. difficile isolates vary in response to bile salts. By analysing 29 isolates, including 16 belonging to the BI/NAP1/027 type, we show that considerable diversity exists in both the rate and extent of C. difficile germination in response to rich medium containing both taurocholate and glycine. Strikingly, we also show that although a potent inhibitor of germination for some isolates, chenodeoxycholate does not inhibit the germination, or outgrowth, of all C. difficile strains. Finally, we provide evidence that components of rich media may induce the germination of C. difficile spores, even in the absence of taurocholate. Taken together, these data suggest that the mechanisms of C. difficile spore germination in response to bile salts are complex and require further study. Furthermore, we stress the importance of studying multiple isolates in the future when analysing the nutrients or chemicals that either stimulate or inhibit C. difficile spore germination.

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Loss of spore OD600 of four C. difficile isolates during incubation with different concentrations of taurocholate.C. difficile spores were heat treated at 60°C for 25 min and then incubated in BHIS supplemented with either 0.1% (w/v) taurocholate (○) or 1% (w/v) taurocholate (•) for 2 h. A) CDC38; B) 7004578; C) 5108111; D) CD2315. The data represent the average of three independent experiments and error bars indicate the standard errors of the means. The dotted line represents the negative control strain (DH361) during incubation with both 0.1% (w/v) taurocholate and 2 mM chenodeoxycholate (a strain found, in preliminary studies, not to germinate when exposed to chenodeoxycholate).
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pone-0032381-g004: Loss of spore OD600 of four C. difficile isolates during incubation with different concentrations of taurocholate.C. difficile spores were heat treated at 60°C for 25 min and then incubated in BHIS supplemented with either 0.1% (w/v) taurocholate (○) or 1% (w/v) taurocholate (•) for 2 h. A) CDC38; B) 7004578; C) 5108111; D) CD2315. The data represent the average of three independent experiments and error bars indicate the standard errors of the means. The dotted line represents the negative control strain (DH361) during incubation with both 0.1% (w/v) taurocholate and 2 mM chenodeoxycholate (a strain found, in preliminary studies, not to germinate when exposed to chenodeoxycholate).

Mentions: To evaluate if different concentrations of taurocholate alter the germination response of C. difficile spores, we incubated spores of four isolates with BHIS supplemented with either 0.1% or 1% (w/v) taurocholate (Fig. 4). Interestingly, we again observed differences among these isolates. For example, CD 2315 was found to germinate similarly in response to both concentrations of taurocholate. Conversely, CDC 38 appeared to germinate at a faster rate when incubated with 1% (w/v) taurocholate than when incubated with 0.1% (w/v) taurocholate and CDC 38 also appeared to show a larger drop in OD600 when exposed to 1% (w/v) taurocholate. This suggests that different isolates of C. difficile may vary in their response to different concentrations of germinants, which could be of interest for future studies.


Spores of Clostridium difficile clinical isolates display a diverse germination response to bile salts.

Heeg D, Burns DA, Cartman ST, Minton NP - PLoS ONE (2012)

Loss of spore OD600 of four C. difficile isolates during incubation with different concentrations of taurocholate.C. difficile spores were heat treated at 60°C for 25 min and then incubated in BHIS supplemented with either 0.1% (w/v) taurocholate (○) or 1% (w/v) taurocholate (•) for 2 h. A) CDC38; B) 7004578; C) 5108111; D) CD2315. The data represent the average of three independent experiments and error bars indicate the standard errors of the means. The dotted line represents the negative control strain (DH361) during incubation with both 0.1% (w/v) taurocholate and 2 mM chenodeoxycholate (a strain found, in preliminary studies, not to germinate when exposed to chenodeoxycholate).
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3285209&req=5

pone-0032381-g004: Loss of spore OD600 of four C. difficile isolates during incubation with different concentrations of taurocholate.C. difficile spores were heat treated at 60°C for 25 min and then incubated in BHIS supplemented with either 0.1% (w/v) taurocholate (○) or 1% (w/v) taurocholate (•) for 2 h. A) CDC38; B) 7004578; C) 5108111; D) CD2315. The data represent the average of three independent experiments and error bars indicate the standard errors of the means. The dotted line represents the negative control strain (DH361) during incubation with both 0.1% (w/v) taurocholate and 2 mM chenodeoxycholate (a strain found, in preliminary studies, not to germinate when exposed to chenodeoxycholate).
Mentions: To evaluate if different concentrations of taurocholate alter the germination response of C. difficile spores, we incubated spores of four isolates with BHIS supplemented with either 0.1% or 1% (w/v) taurocholate (Fig. 4). Interestingly, we again observed differences among these isolates. For example, CD 2315 was found to germinate similarly in response to both concentrations of taurocholate. Conversely, CDC 38 appeared to germinate at a faster rate when incubated with 1% (w/v) taurocholate than when incubated with 0.1% (w/v) taurocholate and CDC 38 also appeared to show a larger drop in OD600 when exposed to 1% (w/v) taurocholate. This suggests that different isolates of C. difficile may vary in their response to different concentrations of germinants, which could be of interest for future studies.

Bottom Line: Strikingly, we also show that although a potent inhibitor of germination for some isolates, chenodeoxycholate does not inhibit the germination, or outgrowth, of all C. difficile strains.Finally, we provide evidence that components of rich media may induce the germination of C. difficile spores, even in the absence of taurocholate.Furthermore, we stress the importance of studying multiple isolates in the future when analysing the nutrients or chemicals that either stimulate or inhibit C. difficile spore germination.

View Article: PubMed Central - PubMed

Affiliation: Clostridia Research Group, School of Molecular Medical Sciences, Centre for Biomolecular Sciences, University of Nottingham, Nottingham, United Kingdom.

ABSTRACT
Clostridium difficile spores play a pivotal role in the transmission of infectious diarrhoea, but in order to cause disease spores must complete germination and return to vegetative cell growth. While the mechanisms of spore germination are well understood in Bacillus, knowledge of C. difficile germination remains limited. Previous studies have shown that bile salts and amino acids play an important role in regulating the germination response of C. difficile spores. Taurocholate, in combination with glycine, can stimulate germination, whereas chenodeoxycholate has been shown to inhibit spore germination in a C. difficile clinical isolate. Our recent studies of C. difficile sporulation characteristics have since pointed to substantial diversity among different clinical isolates. Consequently, in this study we investigated how the germination characteristics of different C. difficile isolates vary in response to bile salts. By analysing 29 isolates, including 16 belonging to the BI/NAP1/027 type, we show that considerable diversity exists in both the rate and extent of C. difficile germination in response to rich medium containing both taurocholate and glycine. Strikingly, we also show that although a potent inhibitor of germination for some isolates, chenodeoxycholate does not inhibit the germination, or outgrowth, of all C. difficile strains. Finally, we provide evidence that components of rich media may induce the germination of C. difficile spores, even in the absence of taurocholate. Taken together, these data suggest that the mechanisms of C. difficile spore germination in response to bile salts are complex and require further study. Furthermore, we stress the importance of studying multiple isolates in the future when analysing the nutrients or chemicals that either stimulate or inhibit C. difficile spore germination.

Show MeSH
Related in: MedlinePlus