Potential indicators of virus transport and removal during soil aquifer treatment of treated wastewater effluent.

Increased water demands have led to a notable interest in the use of treated wastewater for reuse. Typically, this results from the implementation of advanced treatment of final effluent from wastewater treatment plants prior to reuse for potable or non-potable purposes. Soil aquifer treatment (SAT) is a natural treatment process in which water from sources of varying quality is infiltrated into the soil to further improve its quality. The goal of this study was to determine the log10 reduction values (LRVs) of viruses naturally present in treated effluent and evaluate two potential indicators of virus removal and transport, pepper mild mottle virus (PMMoV) and crAssphage, during SAT of treated effluent. Groundwater was sampled at three wells with different attributes within the Sweetwater Recharge Facility (SWRF) in Tucson, AZ. These sites vary greatly in operational parameters such as effluent infiltration rates and wetting/drying cycles, which may influence virus removal efficiency. Detection of adenovirus, enterovirus, PMMoV, and crAssphage were determined by qPCR/RT-qPCR and log10 reduction values (LRVs) were determined. PMMoV and crAssphage were detected in groundwater associated with a set of recharge basins that exhibited shorter wetting/drying cycles and faster infiltration rates. LRVs for crAssphage and PMMoV at this site ranged from 3.9 to 5.8, respectively. Moreover, PMMoV was detected downflow of the SAT sites, indicating the potential degradation of microbial groundwater quality in the region surrounding managed aquifer recharge facilities. Overall, PMMoV and crAssphage showed potential as conservative process indicators of virus removal during SAT, particularly for attribution of LRV credits. Moreover, the detection of these viruses indicated the potential influence of wetting/drying cycles on virus removal by SAT, a parameter that has not yet been studied with respect to biological contaminants.

Removal of fecal indicator bacteria and antibiotic resistant genes in constructed wetlands.

Wastewater discharge evidently increased bacterial diversity in the receiving waterbodies. The objective of this study was to evaluate the effectiveness of a constructed wetland in reducing fecal indicator bacteria (FIB) and antibiotic resistant genes (ARGs). We determined the prevalence and attenuation of fecal indicator bacteria including Escherichia coli and enterococci, along with ARGs, and human-associated Bacteroidales (HF183) markers by quantitative polymerase chain reaction (qPCR) method. Three types of water samples (inlet, intermediate, and outlet) from a constructed wetland were collected once a month from May to December in 2013. The overall reduction of E. coli was 50.0% based on culture method. According to the qPCR result, the overall removal rate of E. coli was only 6.7%. Enterococci were found in 62.5% of the wetland samples. HF183 genetic marker was detected in all final effluent samples with concentration ranging from 1.8 to 4.22 log10 gene copies (GC)/100 ml. Of the ARGs tested, erythromycin resistance genes (ermF) were detected in 79.2% of the wetland samples. The class 1 integrase (intI1) was detected in all water samples with concentration ranging from 0.83 to 5.54 log10 GC/100 ml. The overall removal rates of enterococci, HF183, intI1, and ermF were 84.0%, 66.6%, 67.2%, and 13.1%, respectively.

Bacterial contamination of computer touch screens.

The goal of this study was to determine the occurrence of opportunistic bacterial pathogens on the surfaces of computer touch screens used in hospitals and grocery stores. Opportunistic pathogenic bacteria were isolated on touch screens in hospitals; Clostridium difficile and vancomycin-resistant Enterococcus and in grocery stores; methicillin-resistant Staphylococcus aureus. Enteric bacteria were more common on grocery store touch screens than on hospital computer touch screens.

Wide-spectrum activity of a silver-impregnated fabric.

Fabrics, such as clothing, drapes, pillowcases, and bedsheets are potential sources of pathogenic bacteria and viruses. We found fabrics (ie, professional clothing, pillowcases, and lab coats) treated with a silver-impregnated material to be effective in significantly reducing a wide spectrum of ordinary and drug-resistant microorganisms, including Salmonella, methicillin-resistant Staphylococcus aureus, Propionibacterium acnes, Trichphyton mentagrophytes, and norovirus. Fabrics impregnated with antimicrobial agents help provide an additional barrier to the transport or reservoir of pathogens in health care environments.

Distribution of Bacteria in Dental Offices and the Impact of Hydrogen Peroxide Disinfecting Wipes.

Purpose: The purpose of this study was to characterize the occurrence of heterotrophic plate count bacteria (HPCs), fecal bacterial indicators, and methicillin-resistant Staphylococcus aureus (MRSA) on hard, nonporous surfaces (fomites) commonly found in dental offices, and to assess the impact of a hygienic disinfection intervention on the reduction of these bacteria in the office setting.Methods: Samples of various fomites were collected from dental offices located in Arizona (6) and Illinois (4) and assayed for HPCs, total coliforms, Escherichia coli, and MRSA in order to establish baseline bacterial levels. Dental office personnel were then provided with disposable disinfectant wipes containing hydrogen peroxide to use in the office, and the surfaces were subsequently resampled to assess their impact on the specified bacterial populations.Results: The greatest numbers of HPCs were found on the patients' arm rest and office phones, with dental tool handles and the dentist examination lights yielding the lowest levels. Coliform bacteria and E. coli were also detected on those surfaces demonstrating the highest HPCs, and were cultured from other fomites as well. MRSA was also isolated from 5% of the fomites tested. The use of disinfectant wipes significantly reduced the numbers of HPC bacteria detected on fomites (p=0.002). No total coliforms, E. coli, or MRSA were cultured from disinfected fomites following the hygienic intervention.Conclusion: The use of hydrogen peroxide-impregnated towelettes reduced total bacterial numbers on fomites commonly located in dental offices. Total coliforms, E. coli, and MRSA were reduced to levels below detection.

Evaluation of a disinfectant wipe intervention on fomite-to-finger microbial transfer.

Inanimate surfaces, or fomites, can serve as routes of transmission of enteric and respiratory pathogens. No previous studies have evaluated the impact of surface disinfection on the level of pathogen transfer from fomites to fingers. Thus, the present study investigated the change in microbial transfer from contaminated fomites to fingers following disinfecting wipe use. Escherichia coli (10(8) to 10(9) CFU/ml), Staphylococcus aureus (10(9) CFU/ml), Bacillus thuringiensis spores (10(7) to 10(8) CFU/ml), and poliovirus 1 (10(8) PFU/ml) were seeded on ceramic tile, laminate, and granite in 10-µl drops and allowed to dry for 30 min at a relative humidity of 15 to 32%. The seeded fomites were treated with a disinfectant wipe and allowed to dry for an additional 10 min. Fomite-to-finger transfer trials were conducted to measure concentrations of transferred microorganisms on the fingers after the disinfectant wipe intervention. The mean log10 reduction of the test microorganisms on fomites by the disinfectant wipe treatment varied from 1.9 to 5.0, depending on the microorganism and the fomite. Microbial transfer from disinfectant-wipe-treated fomites was lower (up to <0.1% on average) than from nontreated surfaces (up to 36.3% on average, reported in our previous study) for all types of microorganisms and fomites. This is the first study quantifying microbial transfer from contaminated fomites to fingers after the use of disinfectant wipe intervention. The data generated in the present study can be used in quantitative microbial risk assessment models to predict the effect of disinfectant wipes in reducing microbial exposure.

Transfer efficiency of bacteria and viruses from porous and nonporous fomites to fingers under different relative humidity conditions.

Fomites can serve as routes of transmission for both enteric and respiratory pathogens. The present study examined the effect of low and high relative humidity on fomite-to-finger transfer efficiency of five model organisms from several common inanimate surfaces (fomites). Nine fomites representing porous and nonporous surfaces of different compositions were studied. Escherichia coli, Staphylococcus aureus, Bacillus thuringiensis, MS2 coliphage, and poliovirus 1 were placed on fomites in 10-µl drops and allowed to dry for 30 min under low (15% to 32%) or high (40% to 65%) relative humidity. Fomite-to-finger transfers were performed using 1.0 kg/cm(2) of pressure for 10 s. Transfer efficiencies were greater under high relative humidity for both porous and nonporous surfaces. Most organisms on average had greater transfer efficiencies under high relative humidity than under low relative humidity. Nonporous surfaces had a greater transfer efficiency (up to 57%) than porous surfaces (<6.8%) under low relative humidity, as well as under high relative humidity (nonporous, up to 79.5%; porous, <13.4%). Transfer efficiency also varied with fomite material and organism type. The data generated can be used in quantitative microbial risk assessment models to assess the risk of infection from fomite-transmitted human pathogens and the relative levels of exposure to different types of fomites and microorganisms.