Indicator germs

Drinking water and process water must not contain living pathogens such as salmonella, shigella, cholera vibrios and other organisms capable of causing epidemics. Since, however, the presence of pathogens which are capable of 

The germs generally used to indicate faecal contamination in water are Escherichia coli, faecal streptococci and sulphite-reducing, anaerobic, 

Escherichia coli normally lives in intestinal tracts and, in particular, in the large intestine of human beings and warm-blooded animals. Outside the intestinal tract, it can only live for a short time in water and in the ground and therefore indicates relatively fresh faecal contamination. Thus, when Escherichia coli is present in water, one also has to reckon on the presence of pathogenic intestinal bacteria such as Salmonella, Shigella and cholera vibrios. Escherichia coli is easy to cultivate on culture mediums and can, by reason of its metabolic characteristics in the so-called 

If the enteropathogenicity of coliform strains which have been detected is of interest from a clinical point of view, the serological analyses neces- 

The rule for satisfactory drinking water is that Escherichia coli must not be detectable in 100 ml of drinking water. 

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Oral administration of di(2-ethylhexyl) phthalate at levels of 0, 250, 500 or 1000 mg/kg bw to adult albino rats for 15 days resulted in a significant decrease in sperm count in the epididymus and increased activity of P-glucuronidase, y-GT and lactate dehydrogenase and a decrease in the activity of acid phosphatase in the testes. The authors interpreted these findings as indicating germ-cell depletion and deterioration of the germinal epithelium in the testes (Parmar et al, 1986). 

Fig. 9.2 UV sensitivity of indicator germs E. coli, pathogens, facultative pathogens and viruses with and without photo-reactivation redrawn from Hoyer (1998).

They can also multiply outside the intestinal tract and are indicator germs for hygienically significant impairment of water quality, since they are... 

Animal studies indicate that the pathogenesis of NSAID small intestinal toxicity involves multiple interactions dependent on enterohepatic circulation, epithelial permeability, neutrophil infiltration and bacterial infection [233]. Several investigations [234-238] have suggested that bacterial flora may play a role in the pathogenesis of NSAID bowel injury and Robert and Asano [239] did show more than 25 years ago that germ-free rats are resis-... 

It is well known, for example, that about 5 per cent of the people who become infected with typhoid germs become typhoid carriers and continue indefinitely to harbor an active colony (harmless to them) of typhoid bacilli in their intestinal tracts. There is abundant evidence of graded susceptibility there are many mild cases, and the incubation time in different individuals may be from 3 to 30 days, indicating variable resistance. The fact that about 70 per cent of the carriers are women suggests that the constitutional characteristics which make it possible for individuals to endure the presence of the organisms are in some way sex-linked in their inheritance. The evidence with respect to typhoid carriers, diphtheria carriers, scarlet-fever carriers, poliomyelitis-virus carriers, etc., makes it seem probable that "carriers" enter into the dissemination of many other milder infections, and... 

Positive results in the in vivo mammalian spermatogonial chromosome aberration test indicate that a substance induces structural chromosome aberrations in the germ cells of the species tested. This test measures chromosome events in spermatogonial germ cells and is, therefore, expected to be predictive of induction of inheritable mutations in germ cells. 

A positive response in the rodent dominant lethal test indicates that the test substance may be genotoxic in the germ cells of the treated sex of the test species as evaluated by an increase in the number of dominant lethals evaluated as the sum of pre- and postimplantation loss. A dominant lethal mutation is one occurring in a germ cell, which does not cause dysfunction of the gamete but which is lethal to the fertilized egg or developing embryo. 

Figure 1. Scanning electron micrograph of the cell wall preparations obtained from the different parts of rice grain (7). Caryopsis coat (upper left), aleuron layer (upper right), germ (lower left) and starchy endosperm (lower right). Bars in the picture indicate 5 /zm.

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