Aims: To develop and apply a quantitative protocol for assessing the transfer of bacteria from bleached and undyed fabrics of 100% cotton and 50% cotton + 50% polyester (poly cotton) to ®ngerpads or other pieces of fabric. Methods and Results: Test pieces of the fabrics were mounted on custom-made stainless steel carriers to give a surface area of 1 cm in diameter, and each piece seeded with about 10 5 cfu of Staphylococcus aureus from an overnight broth culture; the inoculum contained 5% fetal bovine serum as the soil load. Transfer from fabric to fabric was performed by direct contact using moist and dry fabrics. Transfers from fabrics to ®ngerpads of adult volunteers were tested using moist, dry and re-moistened pieces of the fabrics, with or without friction during the contact. Bacterial transfer from fabrics to moistened ®ngerpads was also studied. All the transfers were conducted under ambient conditions at an applied pressure of 0á2 kg cm )2 . After the transfer, the recipient ®ngerpads or fabric pieces were eluted, the eluates spreadplated, along with appropriate controls, on tryptic soy agar and the percentage transfer calculated after the incubation of the plates for 24 h at 37°C. Conclusions: Bacterial transfer from moist donor fabrics using recipients with moisture 1 was always higher than that to and from dry ones. Friction increased the level of transfer from fabrics to ®ngerpads by as much as ®vefold. Bacterial transfer from poly cotton was consistently higher when compared with that from all-cotton material. Signi®cance and Impact of the Study: The data generated should help in the development of better models to assess the role fabrics may play as vehicles for infectious agents. Also, the basic design of the reported methodology lends itself to work with other types of human pathogens.

DNA aptamers were developed against murine norovirus (MNV) using SELEX (Systematic Evolution of Ligands by EXponential enrichment). Nine rounds of SELEX led to the discovery of AG3, a promising aptamer with very high affinity for MNV as well as for lab-synthesized capsids of a common human norovirus (HuNoV) outbreak strain (GII.3). Using fluorescence anisotropy, AG3 was found to bind with MNV with affinity in the low picomolar range. The aptamer could cross-react with HuNoV though it was selected against MNV. As compared to a non-specific DNA control sequence, the norovirus-binding affinity of AG3 was about a million-fold higher. In further tests, the aptamer also showed nearly a million-fold higher affinity for the noroviruses than for the feline calicivirus (FCV), a virus similar in size and structure to noroviruses. AG3 was incorporated into a simple electrochemical sensor using a gold nanoparticle-modified screen-printed carbon electrode (GNPs-SPCE). The aptasensor could detect MNV with a limit of detection of approximately 180 virus particles, for possible on-site applications. The lead aptamer candidate and the aptasensor platform show promise for the rapid detection and identification of noroviruses in environmental and clinical samples.

Changing regulations to lower disinfectant byproducts in drinking water is forcing utilities to switch disinfection from chlorine to monochloramine. It is generally unknown whether this will impact positively or negatively on the microbiological quality of drinking water. A utility in Florida, using water with relatively high organic carbon levels from deep wells in several wellfields, made the decision to change its disinfection regime from chlorine to chloramine in order to meet the new regulations. To assess the impacts of such a change on the microbiology of its water supplies, it undertook a number of studies before and after the change. In particular, the presence of the opportunistic pathogens Legionella and Mycobacterium, and also the composition of drinking-water biofilms, were examined. A preliminary synthesis and summary of these results are presented here. Legionella species were widely distributed in source waters and in the distribution system when chlorine was the disinfectant. In some samples they seemed to be among the dominant biofilm bacteria. Following the change to monochloramine, legionellae were not detected in the distribution system during several months of survey; however, they remained detectable at point of use, although with less species diversity. A variety of mycobacteria (21 types) were widely distributed in the distribution system when chlorine was the disinfectant, but these seemed to increase in dominance after chloramination was instituted. At point of use, only four species of mycobacteria were detected. Other changes occurring with chloramination included (a) an altered biofilm composition, (b) increased numbers of total coliforms and heterotrophs and (c) nitrification of water storage tanks. The results suggested that consideration should be given to the microbiological effects of changing disinfection regimes in drinking-water and distribution system biofilms.

The extent of reduction in selected microorganisms was tested during both aerobic wastewater treatment and anaerobic digestion of sludge at the wastewater treatment plant in Ottawa to compare the removal of two encysted pathogenic protozoa with that of microbial indicators. Samples collected included the raw wastewater, the primary effluent, the treated wastewater, the mixed sludge, the decanted liquor, and the cake. All of the raw sewage samples were positive for Cryptosporidium oocysts and Giardia cysts, as well as for the other microorganisms tested. During aerobic wastewater treatment (excluding the anaerobic sludge digestion), Cryptosporidium and Giardia were reduced by 2.96 log10 and 1.40 log10, respectively. Clostridium perfringens spores, Clostridium perfringens total counts, somatic coliphages, and heterotrophic bacteria were reduced by approximately 0.89 log10, 0.96 log10, 1.58 log10, and 2.02 log10, respectively. All of the other microorganisms were reduced by at least 3.53 log10. Sludge samples from the plant were found to contain variable densities of microorganisms. Variability in microbial concentrations was sometimes great between samples, stressing the importance of collecting a large number of samples over a long period of time. In all cases, the bacterial concentrations in the cake (dewatered biosolids) samples were high even if reductions in numbers were observed with some bacteria. During anaerobic sludge digestion, no statistically significant reduction was observed for Clostridium perfringens, Enterococcus sp., Cryptosporidium oocysts, and Giardia cysts. A 1-2 log10 reduction was observed with fecal coliforms and heterotrophic bacteria. However, the method utilized to detect the protozoan parasites does not differentiate between viable and nonviable organisms. On the other hand, total coliforms and somatic coliphages were reduced by 0.35 log10 and 0.09 log10, respectively. These results demonstrate the relative persistence of the protozoa in sewage sludge during wastewater treatment.

The natural habitat of Legionella is the water environment. Little is known about their presence in groundwater in spite of the fact that many millions around the globe regularly rely on groundwaters. This pilot study was aimed at evaluating the occurrence of Legionella in groundwater samples (water and biofilms) collected from various sites. Water and biofilm samples from selected groundwater sources were examined for Legionella using culture media (selective and non-selective) and a semi-nested PCR assay. Innovative approaches such as immunomagnetic separation (IMS) in combination with cultivation and flow cytometry were also evaluated. The findings available thus far show that (a) Legionella could be readily recovered from groundwater samples by cultivation even though their numbers showed considerable variations, (b) surprisingly, the PCR methodology was not yet as sensitive as cultivation and (c) flow cytometry was not directly applicable on natural samples because of debris and the high number of heterotrophic associated microflora from which some members were likely to cross-react with the monoclonal antibody used for separation procedures (IMS).