Colstridium Perfringens

Colstridium Perfringens

	Colstridium Perfringens - Clostridium perfringens is the most important member of the group, anaerobic sulphite reducing clostridia. It is normally present in human and animal faeces, but in much fewer number than E. coli and faecal streptococci. Thus, it is less sensitive as a direct indicator of faecal pollution. The resistant spores of C. perfringens survive in water and in the environment for much longer time than E. coli and other faecal indicator organisms. Their presence in areas remote from human habitation may be due to contamination from birds and wild animals.
Since the spores of C. perfringens are not always inactivated by the usual chlorination procedure in water treatment units, they may occur in small numbers in treated waters.In the absence of other faecal pollution indicators, the presence of C. perfringens indicates remote or intermittent faecal pollution. Therefore it is of much less importance in terms of immediate or direct health risk. It may suggest the need for frequent sampling of water for indicator organisms. The presence of C. perfringens together with coliform organisms but not E. coli confirms the faecal origin of pollution.
The presence of C. perfringens spores in treated water in the absence of E. coli which is known to have been present in the raw water, suggest that the treatment is effective in removing the vegetative cells of indicator organisms. Thus, any potential bacterial pathogen might have also been removed. However, the presence of spores of C. perfringens in water normally does not pose any health problem. These organisms are the normal inhabitants of large intestine of humans and other warm blooded animals like cows, sheep, pigs, poultry etc. and are constantly released through their faeces.
Presence of these bacteria in water indicates faecal pollution, more specifically the recent pollution as these organisms cannot survive for longer periods in water. The main source of waterborne pathogens causing enteric diseases, is water contaminated with faeces of infected persons. Infected persons and carriers shed the pathogens through their faeces along with other normal inhabitants of large intestine. Thus, pathogens, have every chance of entering the waterbodies whenever faecal pollution occurs. Hence, the presence of faecal pollution indicators can also be indirectly used as an indication for the presence of enteric pathogens.
	In classical methods of bacteriological analysis of water we do not determine whether pathogens are actually present. Instead we determine whether the water is polluted by faecal material or not. And also the presence of indicators of faecal pollution does not confirm the presence of pathogens. in water but suggest the possibility of their presence. Conversely the absence of indicator organisms suggest that the pathogens may also be absent. Detection of indicators of faecal pollution in water provides a means of assessing the hygienic quality of drinking water.

Among the above three groups of organisms, coli forms are the most important ones since they are the ideal indicator organisms. Coliform groups, in particular E. coli are constantly present in the human intestine in large numbers and they are excreted in faeces in large numbers each day. They exist in water for longer periods than the intestinal pathogens and other indicator organisms.
They can be determined easily under field conditions. In contrast, faecal streptococci require longer incubation period and clostridia require heating to 80°C making their test procedures very difficult under field conditions.

Home | Site map | Submit Article | Resources | Search