Sludge Watch ==> Campylobacter jejuni becomes non dectactable but viable after stress

[Maureen Reilly]

Sludgewatch Admin:

This news about how Campylobacter jejuni becomes 'viable but not culturable' 
under stressed conditions helps explain why sewage sludge is so dangerous.  
The stress at the anaerobic digesters appears to be sufficient to make these 
pathogens viable but not detectable.

So much for the idea of 'safe sludge'.

Campylobacter jejuni and E coli 0157 were the two major diseases acquired by 
victims of the Walkerton tainted water outbreak.  Thousands of people drank 
fecally contaminated muncipally delivered drinking water.

//////////////////////////////////////////////////////




top

Morphological and physiological responses of Campylobacter jejuni to stress
November 2006

Journal of Food Protection Volume 69, Number 11, pp. 2747-2753(7)
Tangwatcharin, Pussadee; Chanthachum, Suganya; Khopaibool, Prapaporn; 
Griffiths, Mansel W.

Abstract:

Under conditions of stress, cells of Campylobacter assume a coccoid shape 
that may be an evolutionary strategy evolved by the organism to enable 
survival between hosts. However, the physiology of Campylobacter as it 
devolves from spiral to coccoid-shaped morphology is poorly understood.

In this study, conditions influencing the survival of Campylobacter jejuni 
ATCC 35921 in broth were determined. Cells in late log phase were 
resuspended in broth at 4 or 60°C. The culturability of these cold- or 
heat-stressed cell suspensions was determined by spread plate counts and the 
activity of cells by the direct viable count technique and 
5-cyano-2,3-ditolyltetrazolium chloride staining. C. jejuni changed form 
completely from culturable to viable but nonculturable cells (VBNC) within 
25 days at 4°C, and 15 min at 60°C.

Light microscopy of C. jejuni VBNC cells showed that the spiral-shaped cells 
became coccoid, and transmission electron microscopy of C. jejuni VBNC cells 
showed that the outer membrane was lost in aging cell suspensions. 
Furthermore, a limited proteomic study was carried out to compare C. jejuni 
proteins that exhibited increased or decreased synthesis on exposure to 
60°C.