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The objective of this study was to assess how the relative efficiency of N95 respirators and surgical masks might vary with different challenge aerosols, utilizing a standardized manikin head form as a surrogate to human participation. A Collision nebulizer aerosolized B. anthracis Sterne strain endospores and polystyrene latex (PSL) particles to evaluate 11 models of N95 respirators and surgical masks. An automated breathing simulator, calibrated to normal tidal volume and active breathing rate, mimicked human respiration. A manikin head form with N95 respirators or surgical masks, and manikin head form without N95 respirators or surgical masks were placed in the bioaerosol chamber. An AGI-30 sampler filled with phosphate buffered water was fitted behind the mouth of each manikin head form to collect endospore bioaerosol samples. PSL aerosols concentrations were quantified by an ARTI Hand Held Particle Counter. Geometric Mean (GM) relative efficiency of N95 respirators and surgical masks challenged with endospore bioaerosol ranged from 34-65%. In PSL aerosol experiments, GM relative efficiency ranged from 35-64% for 1.3 μm particles. GM filtration efficiency of all N95 and surgical N95 respirators filter media evaluated was ≥99% when challenged with particles ≥0.1 μm. GM filtration efficiency of surgical mask filter media ranged from 70-83% with particles ≥0.1 μm and 74-92% with 1.3 μm PSL particles. Relative efficiencies of N95 respirators and surgical masks challenged with aerosolized B. anthracis endospores and PSL were similar. Relative efficiency was similar between N95 respirators and surgical masks on a manikin head form despite clear differences in filtration efficiency. This study further highlights the importance of face seal leakage in the respiratory protection provided by N95 respirators, and demonstrates it on a human surrogate.

Objective.The objective of this study was to quantify the effectiveness of selected surgical masks in arresting vegetative cells and endospores in an experimental model that simulated contagious patients.Setting.Laboratory.Methods.Five commercially available surgical masks were tested for their ability to arrest infectious agents. Surgical masks were placed over the nose and mouth of mannequin head forms (Simulaids adult model Brad CPR torso). The mannequins were retrofitted with a nebulizer attached to an automated breathing simulator calibrated to a tidal volume of 500 mL/breath and a breathing rate of 20 breaths/min, for a minute respiratory volume of 10 L/min. Aerosols of endospores or vegetative cells were generated with a modified microbiological research establishment-type 6-jet collision nebulizer, while air samples were taken with all-glass impinger (AGI-30) samplers downstream of the point source. All experiments were conducted in a horizontal bioaerosol chamber.Results.Mean arrestance of bioaerosols by the surgical masks ranged from 48% to 68% when the masks were challenged with endospores and from 66% to 76% when they were challenged with vegetative cells. When the arrestance of endospores was evaluated, statistical differences were observed between some pairs, though not all, of the models evaluated. There were no statistically significant differences in arrestance observed between models of surgical masks challenged with vegetative cells.Conclusions.The arrestance of airborne vegetative cells and endospores by surgical masks worn by simulated contagious patients supports surgical mask use as one of the recommended cough etiquette interventions to limit the transmission of airborne infectious agents.

Background Transmission of infection by airborne agents is a risk for health care personnel, patients, and visitors. This risk is heightened in regions without access to environmental controls and personal protective equipment. The ability of 2 prophylactic barriers (ie, semitransparent netting for insect control) to arrest bioaerosols was assessed for potential use within the malarial zones. Methods Barriers (pore sizes of 0.8 mm and 0.25 mm) were challenged with bioaerosols of vegetative cells and endospores of Bacillus anthracis strain Sterne 34F2 using a bioaerosol chamber. Barriers were also challenged with airborne inert polystyrene latex particles of known diameters (0.1, 0.43, 0.6, 1.3, 3.2, and 8.0 μm), and the arrestance provided by barrier with the 0.25 mm pore size was expressed as a function of aerodynamic diameter of challenge aerosols. Results Barrier with the 0.8 mm pore size provided no significant arrestance of aerosols, whereas the barrier with the 0.25 mm pore size provided an 8% arrestance of vegetative cells and a 13% arrestance of endospores. No arrestance at or below the 0.6 μm particle size was observed. Conclusion The level of arrestance provided by these prophylactic barriers does not justify their use as a sole method of preventing transmission.

Aerosol droplet- and airborne-transmitted diseases are an important healthcare concern. The anthrax attacks of 2001, severe acute respiratory syndrome outbreaks in 2003 which resulted in transmission to numerous healthcare personnel (HCP) and concerns about smallpox as a bioterrorist agent have contributed to heightened concern about airborne infectious agents. Respirators and surgical masks can provide respiratory protection against such airborne diseases but their efficacy needs to be assessed. This study describes a method for quantitatively assessing the relative efficiency of respiratory protective equipment (RPE) when challenged with a bioaerosol. Five surgical masks, three N95 respirators and three surgical N95 respirators were evaluated. All are commercially available and used in US healthcare settings. Bacterial aerosols of vegetative Bacillus anthracis strain Sterne 34F2 (a surrogate for pathogenic B. anthracis) were generated with a six-jet Collison nebuliser. To mimic human respiratory breathing, an automated breathing simulator (ABS) calibrated to normal tidal volume and active breathing rate (500 mL/breath and 20 breath/min, respectively) was used. Respirators were placed on manikin head-forms designed for use in cardiopulmonary resuscitation training and used in our investigation as surrogates for HCP. The method showed that a Collison nebuliser could generate monodisperse bacterial aerosol to effectively test RPE total inward leakage. Also, the AGI-30 air samplers, combined with the ABS, provided an accurate method of quantifying RPE relative efficiency. For the 11 RPE this ranged from 34% to 69% with statistically significant differences between several RPE models. We conclude that neither RPE type nor brand name was an indicator of RPE relative efficiency.

Biofilms in potable water distribution systems consist of microorganisms that can survive and grow under the low nutrient concentrations commonly found within water distribution systems. This experiment evaluated the ability of an existing biofilm to reduce the number of introduced microorganisms adhered to materials in an aquatic environment. Ductile iron biofilm sampling coupons were separated into two groups, one had existing biofilm (pre-colonized) and the second group of coupons had no biofilm present (control). Biofilm sampling coupons were challenged by suspensions of individual study organisms consisting of Enterococcus faecium , Escherichia coli , or Aeromonas hydrophilia , and a sterile solution (control). Densities of culturable study organisms on control coupons were compared to densities of these same culturable organisms on biofilm pre-colonized coupons. Results demonstrate that drinking water distribution systems may be vulnerable to the development of potentially pathogenic bacteria in biofilm when lines are initially placed in service. Conclusions are that existing biofilm may serve as a barrier to introduced study organisms.

The ability of aerosolized disinfectant agents to reach exterior and interior spaces of walls and other difficult to access areas has potential as a remediation technique for contained biological contamination. Bacillus subtilis were evaluated against aerosolized solutions of distilled water (dH2O, control), 0.05% chlorine dioxide (ClO2), and 0.6% sodium hypochlorite (NaOCl). Bacillus subtilis endospores were inoculated onto commercially available gypsum board with paper facing. Aerosols generated from a collison nebulizer were directed into a sterile contact chamber housing the inoculated gypsum board for 4, 8, and 12 hour periods. Independent evaluations were conducted of the gypsum board where the organism B. subtilis were exposed to the aerosolized disinfectant. Treatment effects were evaluated through the collection of surface samples before and after exposures. The aerosolized 0.6% sodium hypochlorite solution was the only treatment successful in reducing the total concentration of B. subtilis. Treatment with sodium hypochlorite solution reduced B. subtilis organisms by 1.55-log after 4 h, 1.92-log after 8 h, and 2.50-log after 12 h of exposure, though the difference in log-reduction between exposure periods were not statistically significant.

Modern animal husbandry in the United States and other parts of the world has evolved the swine industry from one that was pasture based into a system based predominantly upon confinement and concentration of animals (Perez-Trallero and Zigorraga 1995; Scarpino and Quinn 1998). Most current animal production facilities rely on confined animal feeding operations (CAFOs) and the addition of subtherapeutic doses of broad-spectrum antibiotics to swine feed as a cheaper way to prevent disease and maintain production yields (Witte 1998). Antimicrobials are known to promote growth in swine and improve the efficiency of feed conversion and can affect bacterial and fungal disease prophylaxis among the confined animals (Davies and Roberts 1999). These treated animals generally gained weight 4–5% faster than other animals not given the antibiotics. Feeding animals antibiotics is associated with the development of antibiotic-resistant bacteria within these animals (Burriel 1997; Nijsten et al. 1996; Threlfall et al. 1993). Antibiotic use within food production animals has raised concern among public health authorities regarding the development of antibiotic-resistant bacteria in dosed animals and the possible subsequent impact on the health of farmworkers and others in proximity to the CAFOs (Witte 1998). Antibiotics are the leading treatment method for bacterial infectious diseases, which remain the most common cause of death worldwide (McGeer 1998). It is widely accepted that antibiotic-resistant pathogens make clinical treatment more difficult (Takafuji 1977). At local levels, areas surrounding swine production facilities might notice a rise in the difficulty of treating human health problems (Haglind and Rylander 1987). These health concerns include, but are not limited to, respiratory problems, infectious disease, and hypersensitive reactions (DuPont and Steele 1987). Those individuals who live or work in proximity to a facility spreading antibiotic-resistant bacteria could face higher exposures to these organisms (Scarpino and Quinn 1998). Gibbs et al. (2004) recovered antibiotic-resistant organisms known to have adverse human health effects both inside and downwind of the facility. It is an important next step to begin evaluating the distance these organisms can travel within bioaerosols to eventually address public health impact. The CAFO evaluated in this study was not using subtherapeutic doses of antibiotics at the time air sampling was conducted; however, the animals had received subtherapeutic levels of antibiotics 4 weeks before sampling. The primary objective of this study was to determine the levels of antibiotic-resistant bacteria, including multidrug-resistant bacteria (those resistant to at least two classes of antibiotics) found in air plumes 25 m upwind and 25, 50, 100, and 150 m downwind from a CAFO. These organisms could affect the health of those in proximity to the facility, such as employees. We hypothesized that the quantity of antibiotic-resistant bacteria would show a negative correlation with distance from the CAFO facility, which would support previous research showing that the animals within CAFOs are significant sources of antibiotic-resistant organisms (Gibbs et al. 2004).

Aerosolized disinfectant use has appealing qualities for inactivation and remediation of biologically contaminated materials. Their ability to reach exterior and interior spaces of walls and difficult to access areas has potential as a simple and cost effective remediation technique. Stachybotrys chartarum was used as a test organism against four disinfectants: chlorine dioxide, sodium hypochlorite, thiabendazole, and cupric sulfate – sodium hydroxide solution. Tests were conducted independently. The organism was exposed for 4 and 8 h periods to the aerosolized disinfectant. The building material was commercially available gypsum board with paper facing. This material was inoculated under sterile conditions. The commercially available treatments were administered as aerosols generated from a collison nebulizer directed into a sterile growth chamber housing inoculated gypsum board. Surface samples were collected before and after exposures to determine treatment effects. The aerosolized chlorine dioxide and sodium hypochlorite treatments successfully inactivated the organism after 8 h of continuous exposure. Key words: Stachybotrys chartarum, aerosolized disinfectant, gypsum board, fungi.

Aims: The efficacy of ultraviolet germicidal irradiation (UVGI) and the UVGI dose necessary to inactivate fungal spores on an agar surface for cultures of Aspergillus flavus and Aspergillus fumigatus were determined. Methods and results: A four-chambered UVGI testing unit with a 9-W, Phillips, low pressure, mercury UVGI lamp in each chamber was used in this study. An aperture was adjusted to provide 50, 100, 150, and 200 µW/cm2 of uniform flux to the surfaces of the Petri dish, resulting in a total UVGI dose to the surface of the Petri dishes ranging from 12 to 96 mJ/cm2. The UVGI dose necessary to inactivate 90% of the A. flavus and A. fumigatus was 35 and 54 mJ/cm2, respectively. Conclusions: UVGI can be used to inactivate culturable fungal spores. Aspergillus flavus was more susceptible than A. fumigatus to UVGI. Significance and impact of the study: These results may not be directly correlated to the effect of UVGI on airborne fungal spores, but they indicate that current technology may not be efficacious as a supplement to ventilation unless it can provide higher doses of UVGI to kill spores traveling through the irradiated zone.Key words: Aspergillus, ultraviolet germicidal irradiation, fungi.

The drinking water distribution system simulator (DSS) from the U.S. EPA was operated with a direct cross-connection of 0.3% wastewater to system volume per day for 70 d. During the cross-connection, tap water, wastewater, and system discharge water were monitored to ensure that the wastewater cross-connection was the source of study organisms and that these organisms were present in the water column of the DSS. The effectiveness of free chlorine levels of 0, 1, 2, and 5 mg/L to inactivate microbes in biofilms on PVC and ductile iron coupons following a wastewater cross-connection was determined. A reduction in organisms occurred after 12 h for both non-chlorinated PVC and ductile iron coupons. This suggests that the study organisms were able to adhere to the biofilm, but were not able to remain in the biofilm. The study organisms were inactivated both in the biofilm and in the water column. Water column data showed that biofilm released culturable heterotrophs and endospores into the water column throughout the 72 h evaluation period at all chlorine levels evaluated. Key words: biofilm, chlorine, wastewater, drinking water, microorganisms, cross-connection.

In recent years, potentially harmfulmicroorganisms such as Stachybotryschartarum have garnered national attentionwhen implicated with indoor air problems. However, accurate assessment of biologicallycontaminated indoor air has proven to beprohibitively labor, time, cost, and trainingintensive. The model developed in this studyaccurately predicts the levels of biologicalindoor air contaminants for the GreaterCincinnati area using a number of independentvariables that can be quickly calculatedwithout expensive, time-consuming methods. Thirty-nine single-family residences in theGreater Cincinnati area were sampled usingAndersen two-stage viable microbial particlesizing sampler instruments loaded with MaltExtract Agar, Trypicase Soy Agar, Czapek'sCellulose Agar, and Corn Meal Agar. After airsampling, the Petri dishes were incubated, thenumber of colonies from each plate wereenumerated, and the total number of viablecolony forming units per cubic meter of airwere calculated. Independent variables (indoorrelative humidity, indoor temperature, outdoormold, season, water damage, visible mold,damaged materials, home age, remediationfactors, health questionnaire, number ofoccupants, and indoor pets) were then compared tothe dependent variable (fungal and bacterialbioaerosol counts) by multiple linearregression using Analyze-it® for Microsoft Excel®. The final air model predicted thetotal number of viable colony forming units percubic meter with 97% accuracy; the goal forthis model was 90% accuracy.

The drinking water distribution system simulator (DSS) from the U.S. EPA was used to assess the effect of long-term wastewater cross-connection on the biofilm of a simulated water distribution system. Initial experimentation determined that at 0.3% wastewater to system volume per day for 90 d injected 0.1% every 8 h into the DSS; study organisms were consistently present in the discharge water sample with only slight aesthetic problems (increased turbidity). During the cross-connection, incoming tap water and wastewater, and system discharge water were monitored to ensure that the source of study organisms was only the wastewater cross-connection and that study organisms were present in the water column of the DSS. Following elimination of the cross-connection, samples showed that study organisms were removed from the water column within 24 h, which was the hydraulic retention time of the system. Increased numbers of heterotrophic organisms were detected in the system discharge following cross-connection. Increased heterotrophs were recovered for the system biofilm, and study organisms, except culturable heterotrophs, were not recovered beyond 24 h. Results indicate that the existing biofilm grew during the cross-connection, and may have inhibited growth of specific study organisms introduced via the cross-connection. Key words: biofilm, wastewater, drinking water, microorganisms, cross-connection.

Contamination of indoor air by microbial pollutants has been increasingly recognized as a public health problem, and may be responsible for building-related illness (BRI) and sick-building syndrome (SBS). Bioaerosols such as fungi, bacteria, and viruses in indoor air can cause allergic and irritant responses, infectious diseases, respiratory problems, and hypersensitivity reactions. People sensitive to indoor environmental problems complain of a wide variety of symptoms ranging from headache, fatigue, nausea, sinus congestion, to eye, nose, and throat irritations.

We determined effects of acidification on sediment aerobic heterotrophic exo-amylase and exo-protease producing microbial populations in addition to effects on the total microbial population. Acidification of microcosms to sediment pHs of 6, 5, 4, and 3 followed by plate counts showed that numbers of total aerobic heterotrophic microbes, as well as numbers exo-amylase producers and exo-protease producers, decreased at pH 3. It appears that pH 3 may represent a critical level of damage. Numbers of total aerobic heterotrophs also decreased at pH 4. Numbers of all groups increased at pH 6. An accompanying change in species composition was observed with acidification, in which a type of microbe with little production of exo-amylase or exo-protease became dominant in the microbial community as pH decreased. Analysis of three metals (Al, Pb, Cu) indicated an increased mobilization of metals from the sediments at low pHs.

The activated sludge process has been used extensively to treat municipal wastewater. The membrane bioreactor (MBR) process is a modification of the conventional activated sludge process where the clarifier is replaced with a membrane system for separation between the mixed liquor and the effluent. This paper presents the biological and physical performance data of a pilot-scale membrane bioreactor system, fed with a synthetic wastewater. At steady state, particularly high effluent quality was obtained and maintained for an extended period of time. Heterotrophic plate counting showed that the membrane retains heterotrophic microorganisms. Bacteriophage MS-2 was used to determine the retention of viruses. The membrane proved to retain the MS-2 virus.

Ultraviolet (UV) light inactivation of bacteria has been well documented; however, few practical applications use UV light as a germicidal agent for indoor air sanitation. This study is a laboratory evaluation of the germicidal efficacy of a hollow ceiling fan blade assembly containing a UV light unit through which selected aerosolized test microorganisms were passed. An experimental system was constructed to simulate the airflow through a rotating hollow fan blade, consisting of an airtight airflow system that housed the statically positioned fan blade unit containing the UV light (power intensity, 64×104 µW/cm2), a microbiological aerosol generation system, and a biological air-monitoring system with sampling ports located upstream and downstream of the UV light. Escherichia coli, Micrococcus luteus, and Bacillus subtilis were aerosolized and separately passed through the hollow UV light-fan blade assembly. Air sampling was conducted using modified all glass impingers. For a single pass (26 msec) of the...

A new membrane filter agar medium (MI agar) containing a chromogen, indoxyl-beta-D-glucuronide, and a fluorogen, 4-methylumbelliferyl-beta-D-galactopyranoside, was developed to simultaneously detect and enumerate Escherichia coli and total coliforms (TC) in water samples on the basis of their enzyme activities. TC produced beta-galactosidase, which cleaved 4-methylumbelliferyl-beta-D-galactopyranoside to form 4-methylumbelliferone, a compound that fluoresced under longwave UV light (366 nm), while E. coli produced beta-glucuronidase, which cleaved indoxyl-beta-D-glucuronide to form a blue color. The new medium TC and E. coli recoveries were compared with those of mEndo agar and two E. coli media, mTEC agar and nutrient agar supplemented with 4-methylumbelliferyl-beta-D-glucuronide, using natural water samples and spiked drinking water samples. On average, the new medium recovered 1.8 times as many TC as mEndo agar, with greatly reduced background counts (< or = 7%). These differences were statistically significant (significance level, 0.05). Although the overall analysis revealed no statistically significant difference between the E. coli recoveries on MI agar and mTEC agar, the new medium recovered more E. coli in 16 of 23 samples (69.6%). Both MI agar and mTEC agar recovered significantly more E. coli than nutrient agar supplemented with 4-methylumbelliferyl-beta-D-glucuronide. Specificities for E. coli, TC, and noncoliforms on MI agar were 95.7% (66 of 69 samples), 93.1% (161 of 173 samples), and 93.8% (61 of 65 samples), respectively. The E. coli false-positive and false-negative rates were both 4.3%. This selective and specific medium, which employs familiar membrane filter technology [corrected] to analyze several types of water samples, is less expensive than the liquid chromogen and fluorogen media and may be useful for compliance monitoring of drinking water.

bacteria has also been shown to interfere with the detection of coliform bacteria. Further, and perhaps most important, members of the total coliform group of bacteria themselves have been implicated in regrowth problems, thus $ving rise to major compliance violations. Bacterial regrowth is affected by a variety of factors. The temperature of the water has been shown to play a major role in bacterial regrowth. An increase in heterotrophic plate count (HPC) organisms has been associated with increasing temperatures following a late spring-summer-autumn sequence in utilities experiencing coliform problems.3 The type of water treatment that is employed by a utility may have a direct impact on microbial growth. It has been demonstrated that the use of ozone in the treatment of water with high humic content, without the subsequent removal of the oxidation products, increases microbial growth in the distribution system.4 This finding is of particular interest because of the proposed increased use of ozonation by water utilities. The incorporation of biological unit processes in water treatment can also affect the nutrient status of the product water. Biological treatment of drinking water, although rarely used in the United States, is common in Europe where the biooxidation of organic matter and ammonia has been demonstrated to be beneficial and cost-efficient. The velocity of water flowing through the mains is an important factor influencing microbial colonization and growth in the distribution system. Pipe sectionswith high water velocities tend to limit microbial protection and reduce sediment accumulation, thus minimizing nutrient entrap ment and protection from exposure to the disinfectant. Conversely, areas of slow flow and dead-end locations have been statistically correlated with water quality deterioration? The presence of iron tubercles has also been associated with microbial growth, especially with colonization by coliform bacteria.6 The maintenance of an adequate disinfectant residual is universally recom

Water quality degradation due to the growth of microorganisms is an area of concern for many water utilities. To date, the procedures developed for determining the amount of biodegradable material present in potable water have utilized heterotrophic non‐coliform bacteria as bioassay seed organisms. A procedure was developed which utilized coliform bacteria as the bioassay organisms for determining the ability of the water to support and promote growth of coliform bacteria. The bioassay procedure can be used to evaluate the effect of various unit processes upon the biological stability of the product water.

The objective of this study was to evaluate the levels of bacteria in the air plume immediately upwind at 25 m and downwind at locations 25 m, 50 m, 100 m, and 150 m from a confined animal feeding operation (CAFO). It was hypothesized that this would give insight into determining the maximal distance that bacterial organisms release from a CAFO could travel, which would be important in determining the optimal siting distance for future CAFO in relation to high population areas. The Andersen two-stage sampler was used to collect all of the bacterial samples from the animal confinement facilities. The data show a marked increase in bacterial CFUs/m3 inside the facility (18,132 CFU/m3 average) versus upwind (63 CFU/m3 average) and a steady downwind decrease out to approximately 150 m. Staphylococcus aureus was found to account for 76% of the organisms recovered. We conclude that the optimal placement of a swine CAFO would be at least 200 m from a residential area.

The ultraviolet germicidal irradiation (UVGI) dose necessary to inactivate fungal spores on an agar surface and the efficacy of UVGI were determined for cultures of Stachybotrys chartarum (ATCC 208877). This study employed a UVGI testing unit consisting of four chambers with a 9-W, Phillips, low pressure, mercury UVGI lamp in each chamber. The testing unit's apertures were adjusted to provide 50, 100, 150, and 200 µW/cm2 of uniform flux to the Petri dish surfaces, resulting in a total UVGI surface dose ranging from 12 to 144 mJ/cm2. The UVGI dose necessary to inactivate 90% of the S. chartarum was greater than the maximum dose of 144 mJ/cm2 evaluated in this study. While UVGI has been used to inactivate several strains of culturable fungal spores, S. chartarum was not susceptible to an appropriate dose of UVGI. The results of this study may not correlate directly to the effect of UVGI on airborne fungal spores. However, they indicate that current technology may not be efficacious as a supplement to ventilation unless it can provide higher doses of UVGI to kill spores, such as S. chartarum, traveling through the irradiated zone.Key words: Stachybotrys chartarum (synonyms S. atra, S. alternana), ultraviolet germicidal irradiation, fungi.

Drinking water regulations under the Final Coliform Rule require that total coliform-positive drinking water samples be examined for the presence of Escherichia coli or fecal coliforms. The current U.S. Environmental Protection Agency-approved membrane filter (MF) method for E. coli requires two media, an MF transfer, and a total incubation time of 28 h. A newly developed MF method, the MI agar method, containing indoxyl-beta-D-glucuronide and 4-methylumbelliferyl-beta-D-galactopyranoside for the simultaneous detection of E. coli and total coliforms, respectively, by means of their specific enzyme reactions, was compared with the approved method by the use of wastewater-spiked tap water samples. Overall, weighted analysis of variance (significance level, 0.05) showed that the new medium recoveries of total coliforms and E. coli were significantly higher than those of mEndo agar and nutrient agar plus MUG (4-methylumbelliferyl-beta-D-glucuronide), respectively, and the background counts were significantly lower than those of mEndo agar (< 5%). Generally, the tap water source, overall chlorine level, wastewater source, granular activated carbon treatment of the tap water, and method of grouping data by E. coli count for statistical analysis did not affect the performance of the new medium.

The need to quantify airborne microorganisms in the commercial microbiology industry (biotechnology) and during evaluations of indoor air quality, infectious disease outbreaks, and agriculture health investigations has shown there is a major technological void in bioaerosol sampling techniques to measure and identify viable and nonviable aerosols. As commercialization of microbiology increases and diversifies, it is increasingly necessary to assess occupational exposure to bioaerosols. Meaningful exposure estimates, by using area or environmental samplers, can only be ensured by the generation of data that are both precise and accurate. The Andersen six-stage viable (microbial) particle sizing sampler (6-STG) and the Ace Glass all-glass impinger-30 (AGI-30) have been suggested as the samplers of choice for the collection of viable microorganisms by the International Aerobiology Symposium and the American Conference of Governmental Industrial Hygienists. Some researchers consider these samplers inconvenient for evaluating industrial bioprocesses and indoor or outdoor environments. Alternative samplers for the collection of bioaerosols are available; however, limited information has been reported on their collection efficiencies. A study of the relative sampling efficiencies of eight bioaerosol samplers has been completed. Eight samplers were individually challenged with a bioaerosol, created with a Collison nebulizer, of either Bacillus subtilis or Escherichia coli. The samplers were evaluated under controlled conditions in a horizontal bioaerosol chamber. During each experimental run, simultaneous samples were collected with a reference AGI-30 to verify the concentration of microorganisms in the chamber from run to run and day to day.(ABSTRACT TRUNCATED AT 250 WORDS)

The actual detection of viruses or the use of an indicator system or systems to assess the presence of pathogenic viruses in contaminated environments is essential for the protection of human health. Herein are considered the possible surrogate relationships between pathogenic viruses and bacterial indicators of fecal pollution in the diverse enviroments of potable water, wastewater, solid waste, shellfish, fish and crops. Assessments are made concerning the reliability of the indicator to identify in these diverse environments viral presence. It is concluded that thus far no one has demonstrated a convincing relationship between the numbers and/or types of different indicator bacteria and the pathogenic viruses themselves, and that the best indicator of viral presence is the actual detection of the virus itself. Nevertheless, the search should continue for more acceptable alternatives which would eliminate the need for the more difficult and time consuming direct testing of pathogenic virus presence.

The radioresistance of coxsackievirus B-2 was studied when the virus was suspended in Eagle minimal essential medium, distilled water, cooked ground beef, and raw ground beef and irradiated at various temperatures in a cobalt-60 gamma radiation source. The number of surviving viruses at given doses of radiation was determined by a plaque assay system. All destruction curves indicated a first-order reaction. When the virus was irradiated in minimal essential medium at temperatures of -30, -60, and -90 C, D values (in Mrad) were 0.69, 0.59, and 0.64, respectively. When the virus was suspended in water and irradiated at -90 C, the D value was 0.53. Cooked ground beef containing the virus was irradiated at temperatures ranging from 16 to -90 C. The D values were 0.70 (16 C), 0.76 (0.5 C), 0.68 (-30 C), 0.78 (-60 C), and 0.81 (-90 C). Raw ground beef containing the virus was irradiated at -30, -60, and -90 C, and the D values were respectively 0.75, 0.71, and 0.68. The D values indicate that the rate of viral inactivation was dependent on the suspending menstrum.

A delayed-incubation membrane-filter technique for fecal coliforms was developed and compared with the immediate fecal coliform test described in Standard Methods for the Examination of Water and Wastewater (13th ed., 1971). Laboratory and field evaluations demonstrated that the delayed-incubation test, with the use of the proposed vitamin-free Casitone holding medium, produces fecal coliform counts which very closely approximate those from the immediate test, regardless of the source or type of fresh-water sample. Limited testing indicated that the method is not as effective when used with saline waters. The delayed-incubation membrane-filter test will be especially useful in survey monitoring or emergency situations when the standard immediate fecal coliform test cannot be performed at or near the sample site or when time and temperature limitations for water sample storage cannot be met. The procedure can also be used for analyzing the bacterial quality of water or waste discharges by a standardized procedure in a central examining laboratory remote from the sample source.

INTRODUCTION INFORMATION presently available concerning the inactivation of viruses in water and wastewater by chlorine and its compounds are limited. Available literature has often been equivocal because standard conditions for testing have not been used. There also occurred undefined chemical conditions in the test systems, a lack of information concerning the types of titrable chlorine actually present in the chlorinated water and the absence of adequate quantitative techniques for detection of animal virus units. Precise knowledge concerning the destruction of viruses in wastewater assumes greater importance as man turns to an ever increasing degree to the re-use of his upstream neighbor's wastewater. Since sewage-contaminated water is a potential health hazard an awareness of the efficiency of applied disinfectants on human enteric pathogens has increased significance. This is particularly true with viruses which are considerably more resistant than the bacteria. Moreover, it is obvious that disinfectants need to be chosen to meet particular needs. To determine which disinfectant species is best suited to meet each specific needs situation, disinfectants must be tested under essentially identical conditions. Thus, this project is a continuing part of the cooperative comparative disinfection study coordinated by the Virology program at the National Environmental Research Center, Cincinnati.

The present invention concerns a spectrometric technique to determine microorganism detection and identification by taking advantage of the inherent extracellular enzymes present in living organisms, as opposed to dead, non-enzyme producing organisms. These enzymes are harnessed in the in vivo reactions with a non-fluorescent dye containing a select organic functional group that is known to be cleaved or hydrolyzed by the certain enzyme. The dye is tailored such that one of the products fluoresces, so that by employing a conventional spectrofluorimeter, the rate of fluorescence can be determined. By subjecting a plurality of samples having different cellular concentrations of viable microorganisms to the same non-fluorescent dye, or by subjecting the same bacterial sample to a number of different non-fluorescent dyes, a pattern of fluorescent rates emerge. By employing the pattern recognition set to standard microorganism fluorescent response curves, microorganism detection and identification can be determined. Thus, the present invention concerns a process for determining microorganism detection, identification and concentration.

The research reported here was undertaken to obtain data on the numbers and types of bacteria emitted into the air from activated sludge and extended aeration sewage treatment plants and to evaluate the fate of these airborne bacteria in the air. The mean bacterial emission rate was 440 bacteria per square meter per second. Volumetric concentration of the airborne bacteria was depleted primarily by atmospheric diffusion and by die-off. Deposition of the bacteria to the ground was less important. The average half-life of the bacteria was 14 seconds. Under average conditions the initial bacterial concentration was reduced by 90% at 100 feet downwind of the source. Of the bacteria collected and cultured on trypticase soy agar, only 5% belonged to the Enterobacteriaceae, and these were primarily Klebsiella, Aerobacter, and Escherichia.

Work by Scarpino in 1972 indicated that disinfection rates are affected by ionic presence. When disinfecting coxackievirus A9 with H0C1 at pH 6.0 in the presence of 0.05M KC1 the effect is to increase the disinfection rate 50 times. Disinfection of coxackievirus A9 at pH 10.0 shows that 0.05M KC1 increases the disinfection rate 10 times. This rate difference due to 0.05M KC1 between the two pH's may be due to the charge on the hypochlorite ion, the change of charge on the surface of the virion, or to a change in the chemical equilibrium of chlorine due to the pH. Studies with poliovirus 1 and 0.05M KC1 showed the same ion effect. When the disinfection of poliovirus 1 with hypochlorous acid (H0C1) was compared with the disinfection of E.coli, the E.coli was disinfected quicker than poliovirus 1. This relationship that viruses are more resistant than the fecal indicator organism E.coli is generally accepted. However, poliovirus 1 was more sensitive to hypochlorite ion (OCl−) than E. coli, when 0.05M KC1 was present in the buffer. Whereas the ion effect was present for coxsackievirus A9 and poliovirus 1, it was not present for E.coli. We have been pursuing this ion effect phenomenon using both chlorine and chloramines. To determine whether this ion effect was present with chloramines, similar tests were run using monochloramine (NH2C1) as the disinfectant. Again the effect held. That is, the presence of KC1 in the buffers increased the efficiency of the disinfectant. This ion-effect was dose dependent between 0.05M KC1 and 0.1M KC1, where the effect was greater with 0.1M KC1. The OCl− and NH2C1 studies were both run at pH 10.0 and at 5°C. Tests were then run to determine whether the effect held for dichloramine (NHC12) at pH 4.5. The ion-effect was present using dichloramine. However, the level of dichloramine dropped from 11.5 ppm to 6.5 ppm during the test. The chloramine loss may be due to the shift of equilibrium as represented by the following equation: With the formation of nitrogen tri-chloride (NC13) the ion-effect could be dissipated if the addition of KC1 was made at a different time. When the chlorine species was formed in the presence of KC1 the effect was present. When the KC1 was added to the already formed specie the effect was not present in the case of monochloramine and much reduced in the case of hypochlorous acid. Therefore, the time of the KC1 addition to the system was critical to the ion-effect phenomenon.