RESUMO
The goal of good toilet hygiene is minimizing the potential for pathogen transmission. Control of odours is also socially important and believed to be a societal measure of cleanliness. Understanding the need for good cleaning and disinfecting is even more important today considering the potential spread of emerging pathogens such as SARS-CoV-2 virus. While the flush toilet was a major advancement in achieving these objectives, exposure to pathogens can occur from failure to clean and disinfect areas within a restroom, as well as poor hand hygiene. The build-up of biofilm within a toilet bowl/urinal including sink can result in the persistence of pathogens and odours. During flushing, pathogens can be ejected from the toilet bowl/urinal/sink and be transmitted by inhalation and contaminated fomites. Use of automatic toilet bowl cleaners can reduce the number of microorganisms ejected during a flush. Salmonella bacteria can colonize the underside of the rim of toilets and persist up to 50 days. Pathogenic enteric bacteria appear in greater numbers in the biofilm found in toilets than in the water. Source tracking of bacteria in homes has demonstrated that during cleaning enteric bacteria are transferred from the toilet to the bathroom sinks and that these same bacteria colonize cleaning tools used in the restroom. Quantitative microbial risk assessment has shown that significant risks exist from both aerosols and fomites in restrooms. Cleaning with soaps and detergents without the use of disinfectants in public restrooms may spread bacteria and viruses throughout the restroom. Odours in restrooms are largely controlled by ventilation and flushing volume in toilet/urinals. However, this results in increased energy and water usage. Contamination of both the air and surfaces in restrooms is well documented. Better quantification of the risks of infection are needed as this will help determine what interventions will minimize these risks.
Assuntos
Aparelho Sanitário , COVID-19 , Humanos , Higiene , SARS-CoV-2 , BanheirosRESUMO
AIMS: To determine the seasonal occurrence and diversity of norovirus (NoV) and human adenovirus (HAdV) in groundwater from sinkholes, and brackish water used for recreational activities in the karst aquifer of the Yucatan Peninsula, Mexico. METHODS AND RESULTS: Hollow fibre ultrafiltration was used to concentrate viruses and standard plaque assay methods were used to enumerate somatic and F+ specific coliphages as viral indicators. Real-time quantitative polymerase chain reaction assays were used to estimate the number of genome copies for NoV strains GI, and GII, and HAdVs. The predominant NoV genotypes and HAdV serotypes were identified by comparative sequence analysis. Somatic and male F+ specific coliphages were detected at concentrations up to 94 and 60 plaque-forming units per 100 ml respectively. The NoV genogroup I (GI) was associated with 50% of the sampled sites during the rainy season only, at concentrations ranging from 120 to 1600 genome copies per litre (GC l-1 ). The NoV genogroup II (GII) was detected in 30 and 40% of the sampled sites during the rainy and dry seasons, respectively, at concentrations ranging from 10 to 290 GC l-1 . During the rainy and dry seasons, HAdVs were detected in 20% of the sites, at concentrations ranging from 24 to 690 GC l-1 . Identification of viral types revealed the presence of NoV GI.2, GII.Pe, GII.P16 and GII.P17, and HAdV F serotypes 40 and 41. CONCLUSIONS: These findings demonstrate that NoVs and HAdVs are prevalent as virus contaminants in the karst aquifer, representing potential health risks particularly during the rainy season, in one of the most important areas used for tourism in Mexico. SIGNIFICANCE AND IMPACT OF THE STUDY: This is one of the few studies conducted in karst aquifers that provide a foundational baseline of the distribution, concentrations and diversity of NoVs and HadVs in these particular environments.
Assuntos
Adenovírus Humanos , Água Subterrânea/virologia , Norovirus , Adenovírus Humanos/classificação , Adenovírus Humanos/genética , Adenovírus Humanos/isolamento & purificação , México , Norovirus/classificação , Norovirus/genética , Norovirus/isolamento & purificação , Microbiologia da ÁguaRESUMO
AIMS: Quantitative data on the doses needed to inactivate micro-organisms on fomites are not available for ultraviolet applications. The goal of this study was to determine the doses of UV light needed to reduce bacteria and murine norovirus (MNV) on hard surface fomites through experimentation and to identify appropriate models for predicting targeted levels of reduction. METHODS AND RESULTS: Stainless steel and Formica laminate coupons were selected as they are common surfaces found in healthcare settings. Test organisms included methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), Clostridium difficile and MNV. The fomites were inoculated with 105 -107 bacteria or virus and exposed to a range of UV doses. The order of resistance to UV irradiation was virus, bacterial spore and vegetative cell. The best fitting inactivation curves suggested nonlinear responses to increasing doses after a 3-4 log reduction in the test organisms. The average UV doses required for a 3 log reduction in the C. difficile, MRSA and VRE were 16 000, 6164 and 11 228 (mJ-s cm-2 ) for stainless steel, respectively, and 16 000, 11 727 and 12 441 (mJ-s cm-2 ) for Formica laminate, respectively. CONCLUSIONS: Higher UV light doses are required to inactivate bacteria and viruses on hard surfaces than in suspension. Greater doses are needed to inactivate bacterial spores and MNV compared to vegetative bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: Quantitative data and models on UV light doses needed to inactivate bacteria and MNV on hard surfaces are now available. The generalizable results of this study can be used to estimate required UV dosages to achieve targeted levels of inactivation based on estimated levels of contamination or to support quantitative microbial risk assessments.
Assuntos
Clostridioides difficile/efeitos da radiação , Desinfecção/métodos , Enterococcus/efeitos da radiação , Staphylococcus aureus Resistente à Meticilina/efeitos da radiação , Norovirus/efeitos da radiação , Animais , Clostridioides difficile/química , Clostridioides difficile/crescimento & desenvolvimento , Desinfecção/instrumentação , Farmacorresistência Bacteriana , Enterococcus/química , Enterococcus/efeitos dos fármacos , Enterococcus/crescimento & desenvolvimento , Fômites/microbiologia , Fômites/virologia , Humanos , Cinética , Meticilina/farmacologia , Staphylococcus aureus Resistente à Meticilina/química , Staphylococcus aureus Resistente à Meticilina/crescimento & desenvolvimento , Camundongos , Modelos Biológicos , Norovirus/química , Norovirus/crescimento & desenvolvimento , Esporos Bacterianos/química , Esporos Bacterianos/crescimento & desenvolvimento , Esporos Bacterianos/efeitos da radiação , Raios Ultravioleta , Vancomicina/farmacologiaRESUMO
AIMS: To investigate the molecular epidemiology, especially temporal variations in genotype distribution, of sapoviruses and Aichi virus 1 (AiV-1) in Arizona, United States, by examining wastewater. METHODS AND RESULTS: A total of 26 wastewater samples (13 influent and 13 effluent) were collected monthly from a wastewater treatment plant and viral strains were identified through nested reverse transcription-PCR followed by cloning and sequencing analysis. Identified sapovirus strains were classified into seven genotypes belonging to three genogroups (GI, GII, and GV): GI.1, GI.2, GI.3, GII.1, GII.2, GII.8 and GV.1, with a clear temporal shift. The majority of AiV-1 strains identified from the wastewater samples were classified into genotype B, and genotype A strains were identified in only two samples. CONCLUSIONS: We identified a number of sapovirus and AiV-1 strains belonging to multiple genotypes in wastewater samples collected over a 13-month period. Our results suggested a temporal shift in prevalent genotypes in the community. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study elucidating the genotype distribution of human sapoviruses and AiV-1 in wastewater in the United States. Wastewater surveillance is especially useful for understanding molecular epidemiology of viruses that are less commonly tested in clinical diagnosis, including sapoviruses and AiV-1.
Assuntos
Kobuvirus/genética , Kobuvirus/isolamento & purificação , Sapovirus/genética , Sapovirus/isolamento & purificação , Águas Residuárias/virologia , Arizona , Genótipo , Humanos , Fatores de TempoRESUMO
AIMS: The goal of this study was to explore various models for describing viral persistence (infectivity) on fomites and identify the best fit models. METHODS AND RESULTS: The persistence of poliovirus over time was studied on three different fomite materials: steel, cotton and plastic. Known concentrations of poliovirus type 1 were applied to the surface coupons in an indoor environment for various lengths of time. Viruses were recovered from the surfaces by vortexing in phosphate buffer. Seven different mathematical models of relative persistence over time were fit to the data, and the preferred model for each surface was selected based on the Bayesian information criterion. CONCLUSIONS: While the preferred model varied by fomite type, the virus showed a rapid initial decay on all of the fomite types, followed by a transition to a more gradual decay after about 4-8 days. Estimates of the time for 99% reduction ranged from 81 h for plastic to 143 h for cotton. A 6 log reduction of recoverable infectivity of poliovirus did not occur during the 3-week duration of the experiment for any of the fomites. SIGNIFICANCE AND IMPACT OF THE STUDY: In protected indoor environments poliovirus can remain infective for weeks. The models identified by this study can be used in risk assessments to identify appropriate strategies for managing this risk.
Assuntos
Fômites/virologia , Modelos Biológicos , Poliovirus/fisiologia , Animais , Teorema de Bayes , Linhagem Celular , Chlorocebus aethiops , Fômites/classificação , Humanos , Poliomielite/transmissão , Poliomielite/virologiaRESUMO
AIMS: In the present study, we conducted a quantitative microbial risk assessment forecasting the exposure to Campylobacter jejuni contaminated surfaces during preparation of chicken fillets and how using a disinfectant-wipe intervention to clean a contaminated work area decreases the risk of infection following the preparation of raw chicken fillet in a domestic kitchen. METHODS AND RESULTS: Using a Monte Carlo simulation of the risk of transferring Camp. jejuni strain A3249, from various surfaces to hands and subsequently transferring it to the mouth was forecasted. The use of a disinfectant-wipe intervention to disinfect contaminated surface area was also assessed. Several assumptions were used as input parameters in the classical Beta-Poisson model to determine the risk of infection. The disinfectant-wipe intervention reduced the risk of Camp. jejuni infection by 2-3 orders on all fomites. CONCLUSIONS: The use of disinfectant wipes after the preparation of raw chicken meat reduces the risk of Camp. jejuni infections. SIGNIFICANCE AND IMPACT OF THE STUDY: This risk assessment shows that the use of disinfectant wipes to decontaminate surface areas after chicken preparation reduces the annual risk of Camp. jejuni infections up to 99·2%, reducing the risk from 2 : 10 to 2 : 1000.
Assuntos
Infecções por Campylobacter/microbiologia , Campylobacter jejuni/efeitos dos fármacos , Desinfetantes/farmacologia , Desinfecção/métodos , Manipulação de Alimentos , Animais , Campylobacter jejuni/crescimento & desenvolvimento , Galinhas , Desinfecção/instrumentação , Manipulação de Alimentos/métodos , Mãos/microbiologia , Humanos , Carne/microbiologiaRESUMO
The goal of this study was to determine the reduction in risk of infection by viruses with the use of an alcohol-based hand sanitizer, used in addition to routine hand washing, in family members in households. A quantitative microbial risk model was used to determine the probability of infection from the concentration of virus on the hands. The model incorporated variation in hand size, frequency of touching orifices (nose, mouth, eyes), and percent transfer to the site of infection, as well as, dose-response for each virus. Data on the occurrence of virus on household members' hands from an intervention study using MS-2 coliphage was used to determine the reduction of viruses on the hands pre- and post-intervention. It was found that the risk of rhinovirus, rotavirus or norovirus infection after the intervention was reduced by 47-98% depending upon the initial concentration of virus on the hands.
Assuntos
Infecções por Caliciviridae/prevenção & controle , Etanol/uso terapêutico , Gastroenterite/prevenção & controle , Higiene das Mãos/métodos , Higienizadores de Mão/uso terapêutico , Infecções por Picornaviridae/prevenção & controle , Infecções Respiratórias/prevenção & controle , Infecções por Rotavirus/prevenção & controle , Mãos/virologia , Humanos , Modelos Teóricos , Norovirus , Probabilidade , Rhinovirus , RotavirusRESUMO
UNLABELLED: The objective of this study was to evaluate the reduction of infection risk due to exposure to Salmonella sp. in kitchen cleaning clothes by the use of a bleach (sodium hypochlorite) cleaner utilizing a continuous-time dynamic exposure model. The only route of exposure considered was hand contamination during cloth use. The occurrence and numbers of Salmonella was studied in 60 homes over a 6-week period in which half disinfected kitchen cleaning clothes with a sodium hypochlorite based disinfectant cleaner. This study demonstrated that a significant risk exists for Salmonella infection from kitchen cleaning clothes in Mexican homes and that this risk can be reduced by almost 100-fold by soaking cleaning clothes in a bleach product. The risks of infection and illness could likely be further reduced by developing a more effective procedure for reducing Salmonella in cleaning clothes treated twice a day with a sodium hypochlorite disinfectant (i.e. longer soaking time) or using a greater concentration of the disinfectant. SIGNIFICANCE AND IMPACT OF THE STUDY: Hygiene intervention is a key strategy to reduce the potential risk of disease-causing micro-organisms in households. There is a lack of understanding of the human health risk associated with the use of contaminated kitchen cleaning cloths. The study used a quantitative microbial risk assessment to estimate the risk associated with the use of kitchen cleaning clothes by using disinfectant products. The results showed that the use of prescribe protocols can reduce the risk of Salmonella infections in household kitchens.
Assuntos
Desinfetantes , Manipulação de Alimentos , Microbiologia de Alimentos , Infecções por Salmonella/prevenção & controle , Hipoclorito de Sódio , Vestuário , Desinfecção/métodos , Humanos , Salmonella/isolamento & purificaçãoRESUMO
AIMS: This study aimed to determine if the children's leisure activities impact the presence of pathogens on their hands and toys. METHODS & RESULTS: To assess the microbiological hazard in playground areas, a pilot study that included 12 children was conducted. We then conducted an intervention study; children's hands and toys were washed before playing. Faecal coliforms, pathogenic bacteria and Giardia lamblia were quantified by membrane filtration, selective media and flotation techniques, respectively; rotavirus, hepatitis A and rhinovirus by RT-PCR. Pilot study results revealed faecal contamination on children's hands and toys after playing on sidewalks and in public parks. Pathogenic bacteria, hepatitis A and G. lamblia on children's hands were also found. In the intervention study, Staphylococcus aureus and Klebsiella pneumoniae were found on children's hands at concentrations up to 2·5 × 10(4) and 1 × 10(4) CFU hands(-1), respectively. E. coli and Kl. pneumoniae were detected on toys (2·4 × 10(3) and 2·7 × 10(4) CFU toy(-1), respectively). Salmonella spp, Serratia spp and G. lamblia cysts were also present on toys. CONCLUSION: Children's play activities influence microbial presence on hands and toys; the transfer seems to occur in both ways. SIGNIFICANCE AND IMPACT OF THE STUDY: Control strategy needs to be implemented to protect children from infectious diseases.
Assuntos
Bactérias/isolamento & purificação , Microbiologia Ambiental , Mãos/microbiologia , Mãos/virologia , Jogos e Brinquedos , Vírus/isolamento & purificação , Criança , Pré-Escolar , Fezes/microbiologia , Fezes/parasitologia , Fezes/virologia , Feminino , Giardia lamblia/isolamento & purificação , Mãos/parasitologia , Humanos , Masculino , Projetos PilotoRESUMO
A microbial risk assessment was conducted to estimate the human health risks from incidental contact recreational activities such as canoeing, boating and fishing in the Chicago Area Waterway System (CAWS) receiving secondary treated, but non-disinfected, effluent from three municipal water reclamation plants. Actual concentrations of the pathogens (pathogenic E. coli [estimated], Giardia, Cryptosporidium, adenovirus, norovirus, enteric virus) detected from the waterway field data collection at locations upstream and downstream of the effluent outfall during dry and wet weather conditions within the recreation season were included in the risk assessment. The results under the current treatment scheme with no disinfection indicated that the total expected gastrointestinal illness (GI) rate per 1000 incidental contact recreational exposure events during combined weather (dry and wet) conditions ranged from 0.10 to 2.78 in the CAWS, which is below the eight illnesses per 1000 swimmers considered tolerable by the United States Environmental Protection Agency. Wet weather conditions contribute to elevated pathogen load to the CAWS; therefore this study determined that disinfecting the effluents of three major WRPs that discharge to the CAWS would result in an extremely small reduction in the aggregate recreation season risk to incidental contact recreators.
Assuntos
Eucariotos/isolamento & purificação , Água Doce/microbiologia , Recreação , Medição de Risco , Vírus/isolamento & purificação , Poluentes da Água/isolamento & purificação , Chicago , Monitoramento Ambiental , Escherichia coli/classificação , Escherichia coli/isolamento & purificação , Eucariotos/classificação , Água Doce/parasitologia , Água Doce/virologia , Humanos , Filogenia , Vírus/classificação , Movimentos da Água , Poluentes da Água/classificação , Tempo (Meteorologia)RESUMO
AIMS: To quantify microbial contamination on kitchen and bathroom surfaces (fomites) in rural Cambodian homes and to compare these concentrations to similar data from the United States and Japan. METHODS AND RESULTS: This study monitored the numbers of faecal coliforms (i.e. thermotolerant coliforms), total coliforms, Escherichia coli and heterotrophic plate count bacteria on household surfaces in a rural village of Cambodia. Faecal coliform levels in Cambodia were highest on moist locations such as the plastic ladle used for sink water, the toilet seat surface and the cutting board surface with 100-fold higher levels of faecal coliform bacteria than E. coli and 100-fold higher levels of faecal coliforms than the US and Japanese studies. CONCLUSIONS: A single public health intervention barrier, such as an improved latrine, is only partially effective for household sanitation. For complete sanitation, multiple environmental barriers may be necessary. These barriers occur in a house constructed with easily washable surfaces, a chlorinated water distribution system, house climate control and cleaning product availability. SIGNIFICANCE AND IMPACT OF THE STUDY: Results of this study can be used to emphasize the importance of increasing household environmental sanitation barriers.
Assuntos
Bactérias/isolamento & purificação , Fômites/microbiologia , Banheiros , Camboja , Escherichia coli/isolamento & purificação , Habitação , Japão , População Rural , Saneamento , Estados UnidosRESUMO
AIMS: To identify and quantify the presence of Escherichia coli, Staphylococcus aureus, Salmonella, hepatitis A and norovirus in households and to assess the effect of chlorine and quaternary ammonium-based disinfectants following a prescribed use. METHODS AND RESULTS: Eleven sites distributed in kitchen, bathroom, pet and children's areas of two groups of 30 homes each: (i) a nonprescribed disinfectant user group and (ii) a disinfectant protocol user group. During the 6-week study, samples were collected once a week except for week one when sample collection occurred immediately before and after disinfectant application to evaluate the disinfectant protocol. The concentration and occurrence of bacteria were less in the households with prescribed use of disinfectants. The greatest reductions were for E. coli (99%) and Staph. aureus (99·9999%), respectively. Only two samples were positive for HAV, while norovirus was absent. Disinfection protocols resulted in a significant (P < 0·05) microbial reduction in all areas of the homes tested compared to homes not using a prescribed protocol. CONCLUSIONS: The study suggests that disinfectant product application under specific protocol is necessary to achieve greater microbial reductions. SIGNIFICANCE AND IMPACT OF THE STUDY: Prescribed protocols constitute an important tool to reduce the occurrence of potential disease-causing micro-organisms in households.
Assuntos
Desinfetantes/farmacologia , Desinfecção/métodos , Cloro/farmacologia , Escherichia coli/isolamento & purificação , Vírus da Hepatite A/isolamento & purificação , Utensílios Domésticos , Produtos Domésticos/microbiologia , México , Norovirus/isolamento & purificação , Compostos de Amônio Quaternário/farmacologia , Salmonella/isolamento & purificação , Staphylococcus aureus/isolamento & purificaçãoRESUMO
AIM: To evaluate the effect of long-term annual land applications of Class B biosolids on soil bacterial diversity at University of Arizona Marana Agricultural Field Center, Tucson, Arizona. METHODS AND RESULTS: Following the final of 20 consecutive years of application of Class B biosolids in March 2005, followed by cotton growth from April to November 2005 surface soil samples (0-30 cm) were collected from control (unamended) and biosolid-amended plots. Total bacterial community DNA was extracted, amplified using 16S rRNA primers, cloned, and sequenced. All 16S rRNA sequences were identified by 16S rRNA sequence analysis and comparison to known sequences in GenBank (NCBI BlastN and Ribosomal Database Project II, RDP). Results showed that the number of known genera (identifiable > 96%) increased in the high rate biosolid plots compared to control plots. Biosolids-amended soils had a broad phylogenetic diversity comprising more than four major phyla: Proteobacteria (32%), Acidobacteria (21%), Actinobacteria (16%), Firmicutes (7%), and Bacteroidetes (6%) which were typical to bacterial diversity found in the unamended arid southwestern soils. CONCLUSION: Bacterial diversity was either enhanced or was not negatively impacted following 20 years of land application of Class B biosolids. SIGNIFICANCE AND IMPACT OF THE STUDY: This study illustrates that long-term land application of biosolids to arid southwestern desert soils has no deleterious effect on soil microbial diversity.
Assuntos
Bactérias/classificação , Esgotos , Microbiologia do Solo , Actinobacteria/genética , Actinobacteria/isolamento & purificação , Arizona , Bactérias/genética , Bactérias/isolamento & purificação , Biodiversidade , Proteobactérias/genética , Proteobactérias/isolamento & purificação , RNA Ribossômico 16S/genética , Esgotos/efeitos adversosRESUMO
The Chicago Area Waterway System (CAWS) is a man-made channel, which serves the Chicago area for the drainage of urban storm water and the conveyance of secondary treated effluent from the Metropolitan Water Reclamation District of Greater Chicago's (District) North Side, Stickney and Calumet water reclamation plants (WRPs). A microbial characterization of the CAWS upstream and downstream of the WRPs and from the WRP outfall was initiated by collecting dry and wet weather samples and analyzing for indicators and pathogens. During dry weather, indicator bacteria (fecal coliform [FC], E. coli [EC], enterococci [EN]) were the most abundant microbial species detected in the CAWS compared to pathogens (Salmonella spp [SA], enteric viruses [EV], adenovirus [AV], norovirus [NV] and Giardia and Cryptosporidium). Pseudomonas aeruginosa [PA] levels in the outfall samples were either lower or equivalent to the CAWS. The wet weather samples had a higher frequency of detection of indicator bacteria and pathogens compared to dry weather samples. Overall, the concentrations of pathogens in the CAWS, representing the weather conditions experienced in a recreational year, were relatively low. The study concluded that the presence of pathogens in the CAWS downstream of the WRPs were due to secondary loading of the waterway under wet weather conditions from combined sewer overflows (CSOs) and other discharges.
Assuntos
Água Doce/química , Microbiologia da Água/normas , Tempo (Meteorologia) , Bactérias/classificação , Bactérias/isolamento & purificação , Chicago , Monitoramento Ambiental , Chuva , Movimentos da Água , Poluição da ÁguaRESUMO
Viruses are believed to be a significant cause of recreationally associated water-borne disease. However, they have been difficult to document because of the wide variety of illnesses that they cause and the limitations in previous detection methods. Noroviruses are believed to be the single largest cause of outbreaks, which have been documented in the published literature 45% (n = 25), followed by adenovirus (24%), echovirus (18%), hepatitis A virus (7%) and coxsackieviruses (5%). Just under half of the outbreaks occurred in swimming pools (49%), while the second largest outbreak occurred in lakes or ponds (40%). The number of reported outbreaks associated with noroviruses has increased significantly in recent years probably because of better methods for virus detection. Inadequate disinfection was related to 69% (n = 18) of swimming pool outbreaks. A lack of required reporting and nonuniform water quality and chlorination/disinfection standards continues to contribute to water-borne recreational disease outbreaks.
Assuntos
Surtos de Doenças , Viroses/epidemiologia , Vírus/isolamento & purificação , Microbiologia da Água , Animais , Recreação , Piscinas , Água/análise , Água/normasRESUMO
AIMS: The purpose of this study was to determine the diversity of bacterial communities associated with bioaerosols generated during land application of biosolids using 16S ribosomal RNA (16S rRNA) PCR. METHODS AND RESULTS: Anaerobically digested Class B biosolids were land applied to an agricultural site located in South Central Arizona. Aerosol samples were collected downwind of the biosolids operations and were collected via the use of SKC Biosamplers and subsequently extracted for the presence of bacterial community DNA. All DNA was amplified using 16S rRNA primers, cloned and sequenced. All sequences were aligned and phylogenetic trees were developed to generate community profiles. The majority of aerosolized bacterial clone sequences belonged to the Actinobacteria and alpha- and beta-proteobacterial taxa. Aerosol samples collected downwind of soil aerosolization produced similar profiles. These profiles differed from upwind and background samples. CONCLUSIONS: No one clone sequence isolated from the aerosol samples could be solely attributed to biosolids; on the contrary, the majority appeared to have arisen from soil. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrates that in dry, arid climates the majority of aerosols associated with biosolids land application appear to be associated with the onsite soil.
Assuntos
Agricultura , Microbiologia do Ar , Bactérias/isolamento & purificação , Monitoramento Ambiental/métodos , Esgotos , Actinobacteria/genética , Actinobacteria/isolamento & purificação , Aerossóis , Bactérias/genética , Monitoramento Ambiental/instrumentação , Genes Bacterianos , Filogenia , Reação em Cadeia da Polimerase/métodos , Proteobactérias/genética , Proteobactérias/isolamento & purificação , RNA Ribossômico 16S/análise , Microbiologia do Solo , VentoRESUMO
The purpose of this study was to determine the prevalence of antibiotic-resistant bacteria and endotoxin in soil after land application of biosolids. Soil was collected over a 15 month period following land application of biosolids, and antibiotic resistance was ascertained using clinically relevant antibiotic concentrations. Ampicillin, cephalothin, ciprofloxacin, and tetracycline resistance were all monitored separately for any changes throughout the 15 month period. Endotoxin soil concentrations were monitored using commercially available endotoxin analysis reagents. Overall, land application of biosolids did not increase the percentage of antibiotic-resistant culturable bacteria above background soil levels. Likewise, land application of biosolids did not significantly increase the concentration of endotoxin in soil. This study determined and established a baseline understanding of the overall effect that land application of biosolids had on the land-applied field with respect to antibiotic-resistant bacterial and endotoxin soil densities.
Assuntos
Bactérias/metabolismo , Farmacorresistência Bacteriana Múltipla , Endotoxinas/análise , Material Particulado/química , Antibacterianos/farmacologia , Bactérias/genética , Bactérias/isolamento & purificação , Monitoramento Ambiental/métodos , Eliminação de Resíduos , Solo/análiseRESUMO
The purpose of this study was to determine aerosolized endotoxin concentrations downwind of a biosolids land application site. Aerosol samples were collected from biosolids land application sites, tractor operation, and an aeration basin located within an open-air wastewater treatment plant. Aerosolized endotoxin above background concentrations was detected from all sites, at levels ranging from below detection up to 1800 EU m-3 of air. Biosolids loading operations resulted in the greatest concentrations of endotoxin (mean 344 EU m-3). As downwind (perpendicular to wind vector) distance increased from sources (2-200 m), levels of endotoxin decreased to near background (without biosolids application) concentrations. Overall, the detected levels of aerosolized endotoxin were within past proposed aerosolized endotoxin limits (250-2000 EU m-3) by other occupational exposure studies. Occasionally, peak concentrations were found to be above these limits. Sites in which soil was being aerosolized resulted in greater concentrations of endotoxin with or without biosolids, which suggested that the majority of endotoxin may in fact be of soil origin. This study evaluated the presence of aerosolized endotoxin from the land application of biosolids and showed that these levels were within ranges for concern suggested by other studies and that this area of research needs further investigation.
Assuntos
Poluentes Atmosféricos/análise , Endotoxinas/análise , Eliminação de Resíduos , Aerossóis , Arizona , Monitoramento Ambiental/métodosRESUMO
AIMS: The purpose of this study was to evaluate the community risk of infection from bioaerosols to residents living near biosolids land application sites. METHODS AND RESULTS: Approximately 350 aerosol samples from 10 sites located throughout the USA were collected via the use of six SKC Biosamplers. Downwind aerosol samples from biosolids loading, unloading, land application and background operations were collected from all sites. All samples were analysed for the presence of HPC bacteria, total coliform bacteria, Escherichia coli, Clostridium perfringens, coliphage, enteroviruses, hepatitis A virus and norovirus. Total coliforms, E. coli, C. perfringens and coliphage were not detected with great frequency from any sites, however, biosolids loading operations resulted in the largest concentrations of these aerosolized microbial indicators. Microbial risk analyses were conducted on loading and land application operations and their subsequent residential exposures determined. CONCLUSIONS: The greatest annual risks of infection occurred during loading operations, and resulted in a 4 x 10(-4) chance of infection from inhalation of coxsackievirus A21. Land application of biosolids resulted in risks that were <2 x 10(-4) from inhalation of coxsackievirus A21. Overall bioaerosol exposure from biosolids operations poses little community risk based on this study. SIGNIFICANCE AND IMPACT OF THE STUDY: This study evaluated the overall incidence of aerosolized micro-organisms from the land application of biosolids and subsequently determined that microbial risks of infection were low for residents close to biosolids application sites.