Twelve strains of different Bacteroides species were tested for their efficiency of detection of bacteriophages from sewage The host range of several isolated phages was investigated The results indicated that there was a high degree of strain specificity Then, by using Bacteroides fragilis HSP 40 as the host, which proved to be the most efficient for the detection of phages, feces from humans and several animal species and raw sewage, river water, water from lagoons, seawater, groundwater, and sediments were tested for the presence of bacteriophages that were active against B fragilis HSP 40 Phages were detected in feces of 10% of the human fecal samples tested and was never detected in feces of the other animal species studied Moreover, bacteriophages were always recovered from sewage and sewage-polluted samples of waters and sediments, but not from nonpolluted samples The titers recovered were dependent on the degree of pollution in analyzed waters and sediments

https://aem.asm.org/content/aem/53/7/1632.full.pdf

Bacteriophages active against Bacteroides fragilis in sewage-polluted waters.

A new procedure for detecting and counting enteroviruses based on the VIRADEN method applied to 10 liters of seawater was examined. It improved the efficiency of detection by taking into account both the number of positive isolations and numbers found with traditional methods. It was then used to quantify viruses in bathing waters. A number of bacterial indicators and bacteriophages were also tested. Cultivable enteroviruses were detected in 55% of the samples, most of which complied with bacteriological criteria. In contrast, viral genomes were only detected in 20% of the samples by reverse transcription-PCR. Somatic coliphages outnumbered all other indicators. F-specific RNA phages were detected in only 15% of the samples, whereas phages infecting Bacteroides thetaiotaomicron were detected in 70% of samples. A numerical relationship between the numbers of enteroviruses and the numbers of enterococci and somatic coliphages was observed. In situ inactivation experiments showed that viruses persisted significantly longer than the bacterial indicators. Only somatic coliphages and bacteriophages infecting Bacteroides persisted longer than the viruses. These results explain the numbers of enteroviruses and indicators in bathing waters attending the numbers usually found in sewage in the area. Somatic coliphages show a very good potential to predict the risk of viruses being present in bathing waters.

Enteroviruses and bacteriophages in bathing waters.

Some New Zealand regional councils are examining the use of faecal streptococci (or the subset, enterococci) to assist in identifying pollution sources, or as better indicators of disease risk in bathing waters than faecal coliforms. However, in spite of worldwide investigation, faecal streptococci have largely failed to fulfil their potential as pollution source (human versus animal) indicators in receiving waters. Many qualifications accompany the use of faecal coliform: faecal streptococci (FC: FS) ratios, and the species identification approach (using biochemical and DNA‐based methods) has produced inconclusive results. Nevertheless, the FC: FS shift method (in which the ratio changes under sample storage) may warrant further investigation. Although reported results vary widely, most studies indicate that faecal streptococci outlive faecal coliforms in receiving waters and are more resistant to sunlight‐induced inactivation. USEPA epidemiological studies showed that enterococcus concentration...

https://www.tandfonline.com/doi/pdf/10.1080/00288330.1993.9516550

Faecal streptococci as faecal pollution indicators: A review. Part II: Sanitary significance, survival, and use

The presence of Salmonella and its relationship with indicator organisms of fecal pollution, such as total coliforms, fecal coliforms and fecal streptococci, was studied at two marine zones in Portugal. Seventeen different Salmonella serotypes were isolated and identified, S. virchow was the most frequently isolated (21.6%). In addition, a high percentage (35.1%) was recorded for some Salmonella serotypes of clinical significance, namely S. enteritidis, S. infantis, S. typhimurium and S. virchow. In any of the samples from the two zones Salmonella was not detected in the absence of any of the indicator organisms. However, the incidence of Salmonella as a function of indicator concentration intervals established by the EEC standards was 0, 10 and 19.3% at guide values of total coliforms, fecal coliforms and fecal streptococci, respectively in the Faro samples (south of Portugal). In contrast, Salmonella incidence rates of 37.5, 36.4 and 33.3% were recorded at the corresponding guide values the Caminha samples (north of Portugal). No significant correlations (p>0.005) were obtained between Salmonella and the indicators at the sampling stations; however, total coliforms and fecal streptococci were the indicators most closely related to Salmonella in Caminha and Faro samples, respectively. Survival experiments in Escherichia coli, Enterococcus faecalis and S. typhimurium, using diffusion chambers, were performed to verify whether the lack of correlation between indicators and Salmonella was due to different inactivation rates in seawater. The results indicate that survival percentages of the three microorganisms tested were similar after 48 h of exposure to seawater.

http://www.biblioteca.uma.es/bbldoc/articulos/16669344.pdf

Occurrence of Salmonella spp in estuarine and coastal waters of Portugal.

The relationships between Salmonella spp and indicator microorganisms (total coliforms, faecal coliforms, faecal streptococci, Clostridium perfringens and coliphages) were investigated in three different aquatic environments affected by wastewater discharges. The results indicated that the statistical correlations obtained depended, basically, on the source of faecal discharges. The microorganisms most closely correlated with Salmonella spp were faecal coliforms and C. perfringens, the latter also yielding the highest linear regression slope values. The detection percentages of Salmonella spp were high even at a low degree of pollution, which allowed detection of the pathogens in the absence of classical indicator microorganisms in the sample.

http://atarazanas.sci.uma.es/docs/articulos/16741110.pdf

J. Sancho

Papers

Viral pollution determination of superficial waters (river water and sea-water) from the urban area of Barcelona (Spain)