The Effect of Cadmium on Indicator Bacteria in Sewage

The effect of cadmium (Cd) on the number of different faecal indicator bacteria in sewage, and on species composition of different indicator bacteria, was studied. Different amounts of Cd were added to aliquots of a sewage sample, and after 0, 4% and 24 h of Cd exposure at 20°C conforms, faecal coliforms, faecal streptococci and Clostridium perfringens were enumerated by the membrane filter method. The Cd-induced reduction in the number of coliforms and faecal coliforms during exposure was found to be greater than the decrease in the number of faecal streptococci. In the case of C. perfringens the Cd concentrations used produced no observable effect on the cell number. The addition of Cd changed the faecal coliforms and faecal streptococci density relationship. Escherichia coli seems to be more resistant to Cd than other coliforms and Streptococcus faecalis var. liquefaciens and Streptococcus durans more resistant to Cd than other faecal streptococci. No influence of Cd on gas production by faecal coliforms was observed. Faecal streptococci and C. perfringens seem to be better indicator bacteria than coliforms and faecal coliforms in evaluating the hygienic quality of Cd polluted sewage.     

A study of the microbiological status of Irish farmhouse cheeses with emphasis on selected pathogenic and spoilage micro-organisms

H.M. COVENEY, G.F. FITZGERALD AND C. DALY. 1994. Ninety-six 25 g samples from 25 Irish farmhouse cheeses, two Irish non-farmhouse cheeses and four foreign cheeses were evaluated for the presence of a variety of micro-organisms, namely, coliforms, faecal streptococci, Staphylococcus aureus , yeasts, moulds, salmonellas and shigellas. Seventeen cheeses, i.e. the soft and semi-soft types, were examined for Listeria monocytogenes. Most of the farmhouse cheeses are currently manufactured from raw milk, but some producers now use heat-treated milk. The incidence of coliforms and faecal coliforms was higher in soft, semi-soft and semi-hard cheeses than in hard types. High levels of contamination by faecal streptococci and non-pathogenic (coagulase-negative) Staph. aureus prevailed in a high proportion of the cheeses. Pathogenic (coagulase-positive) staphylococci, however, were also isolated from 50% of the cheeses, some of which were manufactured from pasteurized milk. Yeasts were found mainly in unpasteurized varieties, especially in the category of soft cheeses. Moulds were isolated from five non-mould-ripened cheeses, as well as from mould-ripened varieties. Salmonellas, shigellas and Listeria monocytogenes were not detected after direct enrichment.     

A multiple logistic model for predicting the occurrence of Campylobacter jejuni and Campylobacter coli in water

A multiple logistic regression model was established to predict the occurrence of Campylobacter jejuni/coli , related to index bacteria such as faecal coliforms, faecal streptococci, and sulphite-reducing clostridia, in a water source in southern Norway. The fitted model indicated that faecal coliforms were strong predictors for C. jejuni/coli , although the water temperature also had a strong influence on results. Sulphite-reducing clostridia, faecal streptococci, and season of the year had no significant influence on the results, in spite of their apparent predictor value as separate variables. The model employed offers a new approach to the relationship between index bacteria and the occurrence of pathogenic bacteria in water. Similar models can also be established in general food microbiology.     

A multiple logistic model for predicting the occurrence of Campylobacter jejuni and Campylobacter coli in water.

A multiple logistic regression model was established to predict the occurrence of Campylobacter jejuni/coli, related to index bacteria such as faecal coliforms, faecal streptococci, and sulphite-reducing clostridia, in a water source in southern Norway. The fitted model indicated that faecal coliforms were strong predictors for C. jejuni/coli, although the water temperature also had a strong influence on results. Sulphite-reducing clostridia, faecal streptococci, and season of the year had no significant influence on the results, in spite of their apparent predictor value as separate variables. The model employed offers a new approach to the relationship between index bacteria and the occurrence of pathogenic bacteria in water. Similar models can also be established in general food microbiology.     

A note on antibiotic resistance in the bacterial flora of raw sewage and sewage-polluted River Tigris in Mosul, Iraq

Polluted water samples collected from the River Tigris in the vicinity of a raw sewage outfall were examined for the incidence of antibiotic resistance among coliform bacteria on three occasions during 1983. Eighty percent or more of the coliform bacteria were resistant to one or more antibiotics. At the same time, raw sewage samples were examined for the incidence of antibiotic-resistant bacteria, and Escherichia coli, Pseudomonas spp. and Staphylococcus spp. were selected for sensitivity testing. Collectively, more than 90% of the 480 strains of the three organisms were resistant to one or more antibiotics. The minimal inhibitory concentration (MIC) of ampicillin for twenty-nine strains including coliforms, E. coli, Klebsiella sp., Serratia sp., Ps. aeruginosa, Pseudomonas sp., Micrococcus sp., Staph. aureus, Streptococcus faecalis and Bacillus sp. from raw sewage and polluted River Tigris water was determined and that for Ps. aeruginosa was 250 micrograms/ml. The high incidence of antibiotic-resistant bacteria in natural waters could be related to the widespread use of antibiotics in this locality.     

A note on antibiotic resistance in the bacterial flora of raw sewage and sewage-polluted River Tigris in Mosul, Iraq

Polluted water samples collected from the River Tigris in the vicinity of a raw sewage outfall were examined for the incidence of antibiotic resistance among coli-form bacteria on three occasions during 1983. Eighty percent or more of the coli-form bacteria were resistant to one or more antibiotics. At the same time, raw sewage samples were examined for the incidence of antibiotic-resistant bacteria, and Escherchia coli, Pseudomonas spp. and Staphylococcus spp. were selected for sensitivity testing. Collectively, more than 90% of the 480 strains of the three organisms were resistant to one or more antibiotics. The minimal inhibitory concentration (MIC) of ampicillin for twenty-nine strains including coliforms, E. coli, Klebsiella sp., Serratia sp., Ps. aeruginosa, Pseudomonas sp., Micrococcus sp., Staph. aureus, Streptococcus faecalis and Bacillus sp. from raw sewage and polluted River Tigris water was determined and that for Ps. aeruginosa was 250 μg/ml. The high incidence of antibiotic-resistant bacteria in natural waters could be related to the widespread use of antibiotics in this locality.     

Antibiotic resistant bacteria in Windermere and two remote upland tarns in the English Lake District

The incidence of antibiotic resistance was determined in over 2000 bacteria which were divided into the following groups: faecal streptococci, coliforms (excluding Escherichia coli), E. coli, Pseudomonas spp. and aquatic bacteria (i.e. bacteria predominant in the lake water which were excluded from the previous four categories). The isolates were obtained from the water of Windermere (English Lake District) and from a sewage effluent which entered the lake. With the exception of the faecal streptococci, the incidence of antibiotic resistance was higher in the bacteria isolated from the lake water than in those from the effluent, and ranked according to groups Pseudomonas spp. greater than E. coli greater than aquatic bacteria greater than coliforms greater than faecal streptococci. The highest incidence of multiple resistance was found among the pseudomonads. When corrected for the relative size of each population the pool of antibiotic resistance in the aquatic bacteria was by far the largest. The incidence of antibiotic resistance in aquatic bacteria isolated from Windermere was, however, lower than in those isolated from two remote upland tarns. This finding may have been due to differences in the species composition of the three sites except that the same results were obtained when only fluorescent pseudomonads were tested. The upland tarns were not totally isolated from man and other animals but did not receive any sewage or other effluents and therefore the results were surprising. Possible explanations include a lack of susceptibility in aquatic bacteria and increased resistance associated with growth in nutrient poor environments.     

Antibiotic resistant bacteria in Windermere and two remote upland tarns in the English Lake District

The incidence of antibiotic resistance was determined in over 2000 bacteria which were divided into the following groups: faecal streptococci, coliforms (excluding Escherichia coli ), E. coli, Pseudomonas spp. and aquatic bacteria (i.e. bacteria predominant in the lake water which were excluded from the previous four categories). The isolates were obtained from the water of Windermere (English Lake District) and from a sewage effluent which entered the lake. With the exception of the faecal streptococci, the incidence of antibiotic resistance was higher in the bacteria isolated from the lake water than in those from the effluent, and ranked according to groups Pseudomonas spp. > E. coli > aquatic bacteria > coliforms > faecal streptococci. The highest incidence of multiple resistance was found among the pseudomonads. When corrected for the relative size of each population the pool of antibiotic resistance in the aquatic bacteria was by far the largest. The incidence of antibiotic resistance in aquatic bacteria isolated from Windermere was, however, lower than in those isolated from two remote upland tarns. This finding may have been due to differences in the species composition of the three sites except that the same results were obtained when only fluorescent pseudomonads were tested. The upland tarns were not totally isolated from man and other animals but did not receive any sewage or other effluents and therefore the results were surprising. Possible explanations include a lack of susceptibility in aquatic bacteria and increased resistance associated with growth in nutrient poor environments.     

Occurrence of Staphylococcus and enteropathogens in soft cheese commercialized in the city of Rio de Janeiro,Brazil

AIMS: To investigate the presence of Staphylococcus aureus, enteropathogenic Escherichia coli (EPEC), Aeromonas spp. and Yersinia spp. in soft cheese commercialized in Rio de Janeiro, Brazil. METHODS AND RESULTS: A total of 45 samples of cheese from three different brands marketed in Rio de Janeiro city were analysed for faecal coliform levels using the Most Probable Number (MPN) technique. The samples were also analysed using conventional methodology for the investigation of food-borne pathogens.High levels of faecal contamination were detected in 95.5% of cheese samples. Staphylococcus aureus was isolated from 20% of samples, of which 17.7% were above the limits allowed by Brazilian legislation. Aeromonas hydrophila and Aer. caviae were detected in 17.7% of the samples. Yersinia spp. were not found in this study. EPEC was isolated from 21.1% of the samples and the most frequently found serogroups were O127, followed by O55 and O26. CONCLUSIONS: Our results showed that 95.5% of cheese samples had high levels of faecal coliforms. The isolation of Staph. aureus, serogroups of EPEC and Aeromonas spp. suggested that the soft cheese commercialized in the city of Rio de Janeiro may represent a health risk for the consumers. SIGNIFICANCE AND IMPACT OF THE STUDY: These results suggest that soft cheese may act as an important vehicle of transmission for well-established pathogens.     

Relation between Aeromonas and faecal coliforms in fresh waters

A possible correlation between the presence of mesophilic aeromonads and the number of faecal coliforms present in three fresh-water habitats subject to differing levels of faecal pollution was investigated. Concentration of Aeromonas spp. between 10(2)-10(9) cfu/100 ml and faecal coliforms of between 9-10(7) cfu/100 ml were found in the waters. In water free from faecal pollution there was no correlation but in polluted waters there was a significant relationship between the numbers of aeromonads, faecal coliform and the concentration of organic matter measured by biological oxygen demand.     

Evolution of the pathogen content during co-composting of winery and distillery wastes

The aim of this study was to monitor some microbial indicators and pathogen contents (sulphite reducers clostridia, total enterobacteriaceae, total coliforms, faecal coliforms (Escherichia coli), enterococci, Staphylococcus aureus and Salmonella spp.) throughout the co-composting of wastes from the winery and distillery industry with other organic residues, as well as the effect of the composting system used. Seven different piles using mixtures of winery-distillery wastes with other organic materials were prepared. P1 and P2 were made using grape stalk (GS), grape marc (GM), exhausted grape marc (EGM) and sewage sludge (SS), whereas in P3 and P4 were also used exhausted grape marc with cow manure (CW) and poultry manure (PM), respectively, using the Rutgers system. Additionally, P2 was watered with vinasse (V). The rest of piles (P5, P6 and P7) were prepared with grape marc, exhausted grape marc, cow manure and poultry manure, using the turning system. The effectiveness of the composting process to reduce the pathogen content was higher in the static aerated piles than in those elaborated with the turning. The relatively high temperatures (50-60 degrees C) reached in some of the piles produced a notable decrease in some microbial groups, such as total and faecal coliforms (E. coli), but the characteristics of the raw materials used notably influenced the pathogen contents of the end-product.     

Quantification of pathogenic micro-organisms in the sludge from treated hospital wastewater

The sludge from hospital waste treatment facilities is a potential source of infectious organisms. The average numbers of micro-organisms in the sludge of hospital wastewater in Taiwan were as follows: total count 8·1 × 10⁷ cfu g⁻¹ (dry weight of sludge), and 1·4 × 10⁶, 3·6 × 10⁵, 1·6 × 10⁵, 2·2 × 10⁵ and 5·5 × 10⁴ cfu g⁻¹ (dry weight of sludge) for total coliforms, faecal coliforms, faecal streptococci, Pseudomonas aeruginosa and Salmonella spp., respectively . Salmonella spp. were detected in 37% (10 of 27) of the sludges from hospital wastewaters. Therefore, the treatment of such sludge to reduce pathogenic micro-organisms should be considered.     

Bacterial species in biofilm cultivated from the end of the Seoul water distribution system

AIMS: To investigate changes in the bacterial population and the safety of the biofilm at the end of the drinking water distribution system in Seoul (Korea), selective media and bacterial community analyses were applied to a semi-pilot galvanized iron pipe (GIP) model. METHODS AND RESULTS: No total coliforms or faecal streptococci were detected on m-Endo or m-Enterococcus agar. No Salmonella spp. and Shigella spp. were detected on bismuth sulphite agar or Hektoen enteric agar, respectively. The latter two media detected coliforms, where m-Endo was negative. Biofilm formation started within 1 week (ca 104 CFU cm(-2)) and exceeded 105 CFU cm(-2) within 6 weeks. Although the fatty acid methyl ester analysis revealed dynamic changes in bacterial composition, Micrococcus, Bacillus, and Pseudomonas spp. were persistent members of the biofilm community. Micrococcus spp. was detected most frequently and in high numbers. CONCLUSIONS: Coliforms and Enterococcus species can be recovered from biofilms in water distribution systems. SIGNIFICANCE AND IMPACT OF THE STUDY: This study illustrates the role of biofilms in the chronic deterioration of the water-distribution system in Seoul (Korea).     

Relation between Aeromonas and faecal coliforms in fresh waters

A possible correlation between the presence of mesophilic aeromonads and the number of faecal coliforms present in three fresh-water habitats subject to differing levels of faecal pollution was investigated. Concentration of Aeromonas spp. between 10²–10⁹ cfu/100 ml and faecal coliforms of between 9–10⁷ cfu/100 ml were found in the waters. In water free from faecal pollution there was no correlation but in polluted waters there was a significant relationship between the numbers of aeromonads, faecal coliform and the concentration of organic matter measured by biological oxygen demand.     

Occurrence ofCandida strains in cases of paronychia

A total of 43 patients, 11 males and 32 females, with paronychia of the fingernails were examined for the presence of Candida spp. The yeast species isolated were identified using standard laboratory methods, including germ-tube production, morphology on rice agar with Tween 80, and mainly fermentation and assimilation of saccharides. In the male group, two Candida species were detected: C. albicans as the dominant species in 9 patients and C. parapsilosis in 2 cases. Similarly, C. albicans was the prevalent species also in females (n = 17); other Candida species detected were C. parapsilosis (n = 7), C. tropicalis (5) and C. krusei (3). In addition to the genus Candida, the following anaerobic and aerobic microorganisms were isolated from patients of both groups: Fusobacterium spp., Bacteroides spp., Staphylococcus aureus, alpha-hemolytic streptococci, group A beta-hemolytic streptococci, Klebsiella pneumoniae, Neisseria spp. and Pseudomonas aeruginosa.     

Salmonellae and pollution indicator bacteria in municipal and food processing effluents and the Cornwallis River

A study was conducted to determine the incidence of fecal coliforms, fecal streptococci, Aeromonas hydrophilia, and Salmonella spp. in the waste discharges of seven sewage treatment plants, four fruit and vegetable canneries, a meat packing plant, a poultry processing plant, and a potato processing plant located along the Cornwallis River in Nova Scotia, Canada. Surface water samples were also collected from 13 locations in the river to assess the impact of these waste discharges on the receiving water quality. The results showed that the final effluents from most of the sewage treatment and processing plants were of very poor bacteriological quality, with the number of indicator bacteria comparable with those found in raw sewage. Salmonellae were isolated from the effluents of the meat and poultry plants and five of the seven sewage treatment plants surveyed. No salmonellae were detected in the effluents of the fruit and vegetable canneries. The impact of the discharge of untreated municipal and food processing wastes on the Cornwallis River water quality was evidenced by the recovery from river water of five Salmonella serotypes, and the high fecal coliform counts which exceeded recommended limit for bathing and shellfish harvesting.     

Population dynamics of Aeromonas spp. in an urban river watershed

Density of Aeromonas spp. at one site in the Buffalo River and at four sites on its upstream tributaries was followed from June 1992–June 1993. Membrane filtration counts of Aeromonas during the summer ranged between 18 and 4000 ml⁻¹, which were one to two logs higher than faecal coliform and faecal streptococci densities. Aeromonas spp. in the Buffalo River, and faecal coliforms, faecal streptococci, and the heterotrophic plate count throughout the watershed, increased by approximately one log during summer rainstorms. However, Aeromonas spp. increased only by a factor of two during rainstorms at the upstream sites. Aeromonas spp. showed a strong positive correlation with both indicator bacteria and total suspended solids at the upstream sites during the summer but not the winter. Correlations between Aeromonas and indicator bacteria remained strong in the Buffalo River during the winter, signifying that different conditions exist in the Buffalo River and its upstream tributaries. The strong correlation between Aeromonas spp. and indicator bacteria in the Buffalo River suggest that, in the absence of media capable of the quantitative recovery of potentially pathogenic aeromonads, standard faecal coliform analyses may adequately assess public health risks from Aeromonas spp. in an urban river used for recreational purposes.     

The effect of a new sewage treatment plant on faecal indicator numbers, campylobacters and bathing water compliance in Morecambe Bay

Until recently, sewage from Morecambe was macerated, but otherwise untreated, and discharged at high water via a short outfall pipe into Morecambe Bay adjacent to a recognized bathing water. In March 1997, a new biological sewage treatment plant came on-line and the effluent was discharged via a longer outfall pipe into the Bay south of Heysham. The effect of the new sewage treatment on the quality of the bathing waters was monitored by testing sea water collected from the three EU designated bathing waters on Morecambe Bay: Morecambe North, Morecambe South and Heysham. After sewage treatment came on-line, the numbers of faecal coliforms and faecal streptococci were lower at Morecambe North and Morecambe South but higher at Heysham. Although the changes in numbers were not always statistically significant, they were sufficient to affect compliance with the EU Bathing Water Directive Imperative (mandatory) standards. Compliance improved markedly at Morecambe North and South but declined at Heysham, the closest bathing site to the new outfall. Numbers of thermophilic campylobacters were similar in both years, which is suggestive of their sources being different from those of the indicator bacteria. Campylobacter lari and urease-positive thermophilic campylobacters (UPTC) were the only species of Campylobacter isolated from Morecambe's bathing waters. Very low numbers of Salmonella were found, with Salm, arizonae the only species isolated.     

Virus and bacteria removal from wastewater by land treatment.

Secondary sewage effluent and renovated water from four wells at the Flushing Meadows Wastewater Renovation Project near Phoenix, Arizona, in operation since 1967, were assayed approximately every 2 months in 1974 for viruses and enteric bacteria during flooding periods. No viruses of Salmonella sp. were detected in any renovated well water samples, and the numbers of fecal coliforms, fecal streptococci, and total bacteria were decreased by about 99.9% in the renovated well waters after the wastewater was filtered through about 9 m of soil.     

Bacterial pollution indicators in the intestinal tract of freshwater fish

A study was made of the occurrence, distribution, and persistence of coliforms, fecal coliforms, and fecal streptococci in the intestinal tract of freshwater fish. A total of 132 fish representing 14 different species were used in various phases of these experiments. Examination of the intestinal contents of 78 fish from moderately polluted sections of the Little Miami River indicated that fecal coliform densities were lowest in bluegills (less than 20 per gram) and highest in catfish (1,090,000 per gram). Levels of fecal streptococci for these two species were 220 and 240,000 per gram, respectively. The occurrence of fecal coliforms in fish caught in this stream reflected the warm-blooded-animal-pollution level of the water. All fish used in this phase of the study were caught during July, August, and September when the water temperatures were between 13 and 18 C. The fate of fecal coliforms and Streptococcus faecalis in the fish intestine indicated that these organisms can probably survive and multiply when fish and water temperatures are 20 C or higher, but only when the organisms are retained in the gut for periods beyond 24 hr. Based on the biochemical reactions for 3,877 coliform strains isolated from 132 freshwater fish of 14 different species, 91.4% of all strains were composed of five IMViC types. In a similar study of the biochemical reactions of 850 streptococci isolated from the intestinal tract of 55 freshwater fish, the predominant strains included S. faecalis and various closely associated biotypes. No consistently recurring pattern for either coliforms or streptococci could be developed to identify species of fish investigated. The composition of the intestinal flora is, however, related in varying degree to the level of contamination of water and food in the environment.