Spatial and temporal microbial pollution patterns in a tropical estuary during high and low river flow conditions.

Spatial and temporal patterns of coastal microbial pollution are not well documented. Our study examined these patterns through measurements of fecal indicator bacteria (FIB), nutrients, and physiochemical parameters in Hilo Bay, Hawai'i, during high and low river flow. >40% of samples tested positive for the human-associated Bacteroides marker, with highest percentages near rivers. Other FIB were also higher near rivers, but only Clostridium perfringens concentrations were related to discharge. During storms, FIB concentrations were three times to an order of magnitude higher, and increased with decreasing salinity and water temperature, and increasing turbidity. These relationships and high spatial resolution data for these parameters were used to create Enterococcus spp. and C. perfringens maps that predicted exceedances with 64% and 95% accuracy, respectively. Mapping microbial pollution patterns and predicting exceedances is a valuable tool that can improve water quality monitoring and aid in visualizing FIB hotspots for management actions.

The use of copper and silver in carbon point-of-use filters for the suppression of Legionella throughput in domestic water systems.

AIMS: To evaluate throughput of seeded Legionella pneumophila bacteria in domestic point-of-use filters. METHODS AND RESULTS: The filters were challenged with tap water seeded with Leg. pneumophila. After multiple challenge events (4.25 x 10(11) CFU per filter), the levels of Legionella were lower in the effluent from the filter containing both copper and silver (mean 4.48 x 10(3) CFU ml(-1)) than in the effluent from the filter containing copper only (1.26 x 10(4) CFU ml(-1); P < 0.001). After a single challenge event of approx. 5 x 10(9) CFU L. pneumophila per filter, there was no significant difference between the levels of Legionella in the effluents from a carbon filter containing copper and a carbon filter with no metals (mean 6.87 x 10(2) and 6.89 x 10(2) CFU ml(-1), respectively; P = 0.985). CONCLUSIONS: Legionella was detected in filter effluent up to 6 weeks after being challenged, indicating that while filters may reduce the levels during an initial contamination event, the exposure is extended as the accumulated bacteria slough off over time. SIGNIFICANCE AND IMPACT OF THE STUDY: This study has provided an understanding of the response of Legionella to the use of silver and copper in domestic point-of-use carbon filters.

Influence of environmental factors on virus detection by RT-PCR and cell culture.

The effects of clay, humic acid, u.v. light and shellfish tissue residues on the detection of poliovirus type 2 from environmental samples by culture and RT-PCR were investigated. RT-PCR showed 10-100 times greater sensitivity for PV2 detection in the absence of sample contaminants than did culture by plaque assay in BGM cell monolayers. Bentonite clay (100-1000 mg l-1) and shellfish tissue residues reduced virus detection by plaque assay, but the effect of bentonite was mitigated by simple elution procedures. Bentonite clay, humic acid (5-150 mg l-1) and mussel tissue reduced virus detection by RT-PCR by between 1 and 8 logs, although this was mitigated in part by elution and Sephadex filtration of extracts. Sephadex filtration of samples reduced culturable PV2 by 32-50%. Exposure of PV2 in water to u.v. light reduced culturability of PV2 but not detection by RT-PCR. This study demonstrates that virus detection in environmental samples is strongly influenced by naturally occurring substances and disinfection approaches. The accuracy of results of viral analyses of this nature should be carefully scrutinized with respect to sample constituents.