在饮用水中协同检测“粪型大肠菌群”的试验方法

阐述了在饮用水中检测"粪型大肠菌群"的意义,强调了大肠菌群与粪型大肠菌群的关系,总结出"粪型大肠菌群"的检测条件。     

Validity of fecal coliforms, total coliforms, and fecal streptococci as indicators of viruses in chlorinated primary sewage effluents.

Quantities of combined chlorine that usually destroyed more than 99.999% of the indigenous fecal coliforms, total coliforms, and fecal streptococci in primary sewage effluents destroyed only 85 to 99% of the indigenous viruses present. Viruses were recovered from five of eight chlorinated primary effluents from which fecal coliforms were not recovered by standard most-probable-number procedures. The limited volumes of such chlorinated effluents that can be tested for indicator bacteria with currently available multiple-tube and membrane filter techniques restrict the value of fecal coliforms, fecal streptococci, and even total coliforms as indicators of viruses in these effluents. Although fecal coliforms and fecal streptococci are useful indicators of viruses in effluents from which these bacteria are recovered, the absence of these bacteria and even total coliforms from disinfected effluents (in standard tests) does not assure that viruses are also absent.     

Validity of fecal coliforms, total coliforms, and fecal streptococci as indicators of viruses in chlorinated primary sewage effluents.

Quantities of combined chlorine that usually destroyed more than 99.999% of the indigenous fecal coliforms, total coliforms, and fecal streptococci in primary sewage effluents destroyed only 85 to 99% of the indigenous viruses present. Viruses were recovered from five of eight chlorinated primary effluents from which fecal coliforms were not recovered by standard most-probable-number procedures. The limited volumes of such chlorinated effluents that can be tested for indicator bacteria with currently available multiple-tube and membrane filter techniques restrict the value of fecal coliforms, fecal streptococci, and even total coliforms as indicators of viruses in these effluents. Although fecal coliforms and fecal streptococci are useful indicators of viruses in effluents from which these bacteria are recovered, the absence of these bacteria and even total coliforms from disinfected effluents (in standard tests) does not assure that viruses are also absent.     

Survival of Salmonella adelaide and fecal coliforms in coarse sands of the swan costal plain, Western Australia.

The survival of Salmonella adelaide and fecal coliforms in two coarse sands influenced by two sources of septic tank effluent was studied. The experiments were conducted in conditions that reflected the soil environment beneath functioning septic tank systems. Significant differences in survival were found with different effluent sources. In one experiment the survival of S. adelaide was similar to that of fecal coliforms; in the other it was not. The nonuniform, multiphasic nature of survival curves was variability observed in these experiments suggests that the application of such survival data for establishing management criteria for septic tank systems--by, for example, the use of soil moisture characteristic curves to give estimates of movement in the soil--is inappropriate.     

Microtechnique for isolating fecal coliforms from soil.

A most-probable-number microtitration technique for isolating fecal coliforms from soil was developed. A correlation coefficient of 0.86, with a 95% confidence interval of 0.76 less than zeta less than 0.92, was obtained when this technique was compared with the standard elevated-temperature fecal coliform most-probable-number procedure.     

Modification of delayed-incubation procedure for detection of fecal coliforms in water

Three holding media, including the vitamin-free Casitone holding medium (m-VFC) recommended by Standard Methods for the Examination of Water and Wastewater for use with the delayed-incubation membrane filter procedure, were compared for their ability to maintain viability of fecal coliforms. Each medium was tested according to the procedure described in the above reference with 60 to 80 pure cultures of fecal coliforms and a variety of natural water samples containing fecal coliforms. Fecal coliform recovery with m-ST holding medium (containing ethanol, sulfanilamide, and Tris [pH 8.6] was significantly greater than recovery with m-VFC (containing vitamin-free casein hydrolysate, sodium benzoate, sulfanilamide, and ethanol). Recovery with m-VFC, was, in turn, significantly greater than with NSB medium (containing nutrient broth, boric acid, and NaCl as major ingredients). Fecal coliform counts obtained with m-ST by the delayed-incubation membrane filter procedure were higher than counts obtained by the standard immediate incubation. This result suggested that some of the sublethally injured fecal coliforms in natural water samples may have recovered during the incubation period. We propose that m-ST be used in place of m-VFC for the delayed-incubation membrane filter procedure.     

Comparison of culturable fecal coliforms and Escherichia coli enumeration in freshwaters

Fecal coliforms (FC) counts were compared with Escherichia coli counts in differently contaminated freshwater samples (n = 166). FC were enumerated by plate count on triphenyl 2,3,5-tetrazolium chloride Tergitol medium. Escherichia coli were enumerated by the most probable number microplate method based on the detection of glucuronidase activity. FC and E. coli counts were highly correlated; an average E. coli/FC ratio equal to 0.77 was found, meaning that on average, 77% of FC were E. coli. Knowing the E. coli/FC ratio allows us to convert the historical microbiological quality data expressed in FC counts into E. coli abundance and thus to compare with present and future monitoring data that are (or will be) based on E. coli enumeration.     

Survival of Salmonella in bathrooms and toilets in domestic homes following salmonellosis

The survival and environmental spread of Salmonella bacteria from domestic toilets was examined in homes, where a family member had recently suffered an attack of salmonellosis. In four out of six households tested, Salmonella bacteria persisted in the biofilm material found under the recess of the toilet bowl rim which was difficult to remove with household toilet cleaners. In two homes Salmonella bacteria became incorporated into the scaly biofilm adhering to the toilet bowl surface below the water line. Salmonella enteritidis persisted in one toilet for 4 weeks after the diarrhoea had stopped, despite the use of cleaning fluids. Salmonellas were not isolated from normally dry areas such as, the toilet seat, the flush handle and door handle. Toilet seeding experiments were set up with Salmonella enteritidis PT4 to mimic environmental conditions associated with acute diarrhoea. Flushing the toilet resulted in contamination of the toilet seat and the toilet seat lid. In one out of three seedings, Salmonella bacteria were also isolated from an air sample taken immediately after flushing, indicating that airborne spread of the organism could contaminate surfaces in the bathroom. In the seeded toilet Salmonella bacteria were isolated from the biofilm in the toilet bowl below the waterline for up to 50 d after seeding, and also on one occasion from the bowl water. The results suggest that during diarrhoeal illness, there is considerable risk of spread of Salmonella infection to other family members via the environment, including contaminated hands and surfaces in the toilet area.     

Modification of delayed-incubation procedure for detection of fecal coliforms in water.

Three holding media, including the vitamin-free Casitone holding medium (m-VFC) recommended by Standard Methods for the Examination of Water and Wastewater for use with the delayed-incubation membrane filter procedure, were compared for their ability to maintain viability of fecal coliforms. Each medium was tested according to the procedure described in the above reference with 60 to 80 pure cultures of fecal coliforms and a variety of natural water samples containing fecal coliforms. Fecal coliform recovery with m-ST holding medium (containing ethanol, sulfanilamide, and Tris [pH 8.6] was significantly greater than recovery with m-VFC (containing vitamin-free casein hydrolysate, sodium benzoate, sulfanilamide, and ethanol). Recovery with m-VFC, was, in turn, significantly greater than with NSB medium (containing nutrient broth, boric acid, and NaCl as major ingredients). Fecal coliform counts obtained with m-ST by the delayed-incubation membrane filter procedure were higher than counts obtained by the standard immediate incubation. This result suggested that some of the sublethally injured fecal coliforms in natural water samples may have recovered during the incubation period. We propose that m-ST be used in place of m-VFC for the delayed-incubation membrane filter procedure.     

Isolation of fecal coliforms from pristine sites in a tropical rain forest

Samples collected from water accumulated in leaf axilae of bromeliads (epiphytic flora) in a tropical rain forest were found to harbor fecal coliforms. Random identification of fecal coliform-positive isolates demonstrated the presence of Escherichia coli. This bacterium was also isolated from bromeliad leaf surfaces. These data indicate that E. coli may be part of the phyllosphere microflora and not simply a transient bacterium of this habitat. The isolation of fecal coliforms from these sites was unexpected and raises questions as to the validity of using fecal coliforms as indicators of biological water quality in the tropics.     

Membrane filter method for recovery of fecal coliforms in chlorinated sewage effluents.

The standard one-step M-FC broth-membrane-filter procedure for recovery of fecal coliforms from chlorinated sewage effluents is much less effective than the multiple-tube (most-probable-number) technique. A two-step membrane-filter method, using a pre-enrichment technique with phenol red lactose broth and incubation at 35 degrees C for 4 h, followether 18+/-2 h, enhanced fecal coliform recovery from chlorinated effluents. The results of 126 comparisons using chlorinated effluents from five wastewater plants showed that fecal coliform recovery by using the two-step membrane-filter method is comparable to that using the multiple-tube procedure.     

Short incubation of presumptive media for detection of fecal coliforms in shellfish.

Positive fecal coliform most-probable number results were compiled from 7,701 shellfish samples examined over 9 years. Generally, less than 2% of all positive reactions in EC medium are results of inoculations from presumptive media positive at the maximum (48-h) incubation period.     

Detection of fecal coliforms in water by using [14C]mannitol

Interest in rapid bacterial detection methods for sanitary indicator bacteria in water prompted a study of the use of [U-14C]mannitol to detect fecal coliforms (FC). A simple method which used m-FC broth, membrane filtration, and two-temperature incubation (35 degrees C for 2 h followed by 44.5 degrees C for 2.5 h) was developed. [U-14C]mannitol was added to the medium, and the temperature was raised to 44.5 degrees C after 2 h at 35 degrees C. 14CO2 was collected as Ba14CO3 and assayed by liquid scintillation spectroscopy. Correlations were examined between FC cell numbers at the start of incubation (standard 24-h FC test) and Ba14CO3 counts per minute after 4.5 h. Results indicated that FC numbers ranging from 1 x 10(1) to 2.1 x 10(5) cells could be detected in 4.5 h. Within-sample reproducibility at all cell concentrations was good, but sample-to-sample reproducibility was variable. Comparisons between m-FC broth and m-FC broth modified by substituting D-mannitol for lactose indicated that the standard m-FC broth was the better test medium. Results from experiments in which dimethyl sulfoxide was used to increase permeability of FC to [U-14C]mannitol indicated no increase in 14CO2 production due to dimethyl sulfoxide. Detection of FC by this method may be useful for rapid estimation of FC levels in freshwater recreational areas, for estimating the quality of potable source water, and potentially for emergency testing of potable water, suspected of contamination due to distribution line breaks or cross-connections.     

Isolation of fecal coliforms from pristine sites in a tropical rain forest.

Samples collected from water accumulated in leaf axilae of bromeliads (epiphytic flora) in a tropical rain forest were found to harbor fecal coliforms. Random identification of fecal coliform-positive isolates demonstrated the presence of Escherichia coli. This bacterium was also isolated from bromeliad leaf surfaces. These data indicate that E. coli may be part of the phyllosphere microflora and not simply a transient bacterium of this habitat. The isolation of fecal coliforms from these sites was unexpected and raises questions as to the validity of using fecal coliforms as indicators of biological water quality in the tropics.     

Detection of fecal coliforms in water by using [14C]mannitol.

Interest in rapid bacterial detection methods for sanitary indicator bacteria in water prompted a study of the use of [U-14C]mannitol to detect fecal coliforms (FC). A simple method which used m-FC broth, membrane filtration, and two-temperature incubation (35 degrees C for 2 h followed by 44.5 degrees C for 2.5 h) was developed. [U-14C]mannitol was added to the medium, and the temperature was raised to 44.5 degrees C after 2 h at 35 degrees C. 14CO2 was collected as Ba14CO3 and assayed by liquid scintillation spectroscopy. Correlations were examined between FC cell numbers at the start of incubation (standard 24-h FC test) and Ba14CO3 counts per minute after 4.5 h. Results indicated that FC numbers ranging from 1 x 10(1) to 2.1 x 10(5) cells could be detected in 4.5 h. Within-sample reproducibility at all cell concentrations was good, but sample-to-sample reproducibility was variable. Comparisons between m-FC broth and m-FC broth modified by substituting D-mannitol for lactose indicated that the standard m-FC broth was the better test medium. Results from experiments in which dimethyl sulfoxide was used to increase permeability of FC to [U-14C]mannitol indicated no increase in 14CO2 production due to dimethyl sulfoxide. Detection of FC by this method may be useful for rapid estimation of FC levels in freshwater recreational areas, for estimating the quality of potable source water, and potentially for emergency testing of potable water, suspected of contamination due to distribution line breaks or cross-connections.     

Antibiotic resistance among different species of fecal coliforms isolated from water samples.

The distribution of resistance to ampicillin, chloramphenicol, sulfonamides, tetracycline, and streptomycin among fecal coliforms in sewage, surface waters, and sea water was investigated. The incidence of resistant strains among isolates varied significantly among the water samples, without obvious connection with the water source or the level of pollution. The average frequency of multiple resistance was not always high in the same samples in which the overall resistance was high. The species composition varied considerably in different water samples. A significant correlation was observed between the relative frequency of Klebsiella species and the incidence of ampicillin resistance in water samples. The importance of species composition of fecal coliforms, affected by their source and by the aquatic environment, on the resistance pattern is noted.     

Rainfall-induced release of fecal coliforms and other manure constituents: comparison and modeling

Modeling release of fecal coliforms is an important component of fate and transport simulations related to environmental water quality. Manure constituents other than fecal coliforms may serve as natural tracers of fecal contamination provided that their release from manure to runoff is similar to the fecal coliform release. The objectives of this work were to compare release of fecal coliforms (FC), chloride (Cl-), organic carbon (OC), and water-soluble phosphorus (P) from dissolving manure and to assess the performance of three models in describing the observed release. Bovine manure was applied on 0.5- by 0.3-m bare and vegetated subplots with 20% slope on sandy loam and clay loam soils. Concentrations of Cl-, FC, OC, and P were measured in runoff collected from troughs at the edges of the subplots at 5-min intervals during 1-h rainfall simulations. The one-parametric exponential model and two-parametric Vadas-Kleinman-Sharpley model and Bradford-Schijven model were fitted to the data. The Bradford-Schijven model had uncorrelated parameters, one of which was linearly related to the irrigation rate, and another parameter reflected the presence or the absence of vegetation. Kinetics of the FC release from manure was similar to the release kinetics of P and OC. The Bradford-Schijven model is recommended to simulate the release of manure constituents.     

Evaluation of the 7-h membrane filter test for quantitation of fecal coliforms in water

The 7-h fecal coliform (FC) test for detection of FC organisms in water was evaluated to establish its validity and usefulness for emergency and disaster situations. The waters tested consisted of routine samples collected for public health surveillance and enforcement purposes. A total of 984 water samples from throughout California were assayed. These included samples from coastal salt waters, rivers, canals, and reservoirs, in addition to potable and miscellaneous freshwater sources. A portion of each sample was tested concurrently by both the 7-h FC test and the most-probable-number FC five-tube test. The 7-h FC test samples were incubated for 7 to 7.25 h at 41.5 degrees C. Overall, greater than 90% agreement was obtained between the methods in determining whether the water quality was acceptable or unacceptable. Statistical analysis of the 984 samples confirmed that the 7-h FC method was a suitable alternative to the most-probable-number FC method for evaluation of freshwater samples. During emergencies or disasters, the 7-h FC test could provide a means for detection of fecal contamination of water with results available in less than 1 day.     

Relationship among fecal coliforms, Escherichia coli, and Salmonella spp. in shellfish

The relationship of fecal coliforms, Escherichia coli, and Salmonella spp. was examined in freshly harvested and stored shellfish. In 16 of 40 freshly collected oyster samples, fecal coliform levels were above the recommended wholesale level suggested by the National Shellfish Sanitation Program (less than or equal to 230/100 g), and Salmonella spp. were present in three of these samples. Salmonella spp. were not, however, present in any sample containing less than 230 fecal coliforms per 100 g. Analysis of the data suggests that low fecal coliform levels in both fresh and stored oysters are good indicators of the absence of Salmonella spp., but that high levels of fecal coliforms are somewhat limited in predicting the presence of Salmonella spp. E. coli levels correlated very strongly with fecal coliform levels in both fresh and stored oysters and clams, suggesting that there is no advantage in replacing fecal coliforms with E. coli as an indicator of shellfish quality.