Determination of water quality variables, endotoxin concentration, and Enterobacteriaceae concentration and identification in southern High Plains dairy lagoons.

The objectives of this study were to determine the concentration of endotoxin, determine 20 water quality variables, and identify and enumerate fungal and bacterial pathogens from United States southern High Plains dairy lagoons and control lakes during summer and winter. Water samples were collected in triplicate from the north, south, east, and west quadrants of each body of water. The mean (+/- SEM) winter dairy lagoon endotoxin concentration was significantly higher (9,678+/-1,834 ng/mL) than the summer concentration (3,220+/-810 ng/mL). The mean endotoxin concentration of the 2 control lakes (summer: 58.1+/-8.8 ng/mL; winter: 38.6+/-4.2 ng/mL) was significantly less than that of the dairy lagoons. Two hundred-one Salmonella enterica spp. isolates were identified, 7 serovars were recovered from the dairy lagoons, and 259 Salmonella ssp. were identified from 5 other dairy locations (milk barn, ditch effluent, settling basin, feed alley pad flush, and center pivots). Twenty-eight Salmonella spp. were identified from center pivot water. Escherichia coli O157:H7 pathogens were isolated from other dairy locations but not from lagoons. Neither Salmonella spp. nor E. coli O157:H7 were identified from control lakes. Enterobacteriaceae opportunistic pathogens were isolated from both dairies and control lakes. Important mesophilic and thermophilic catabolic (to manure biosolids) fungal isolates were identified from dairy effluent locations, but no thermophilic fungal isolates were cultured from the control lakes. Adequate curing of green forage following center pivot irrigation is important to kill lagoon water enteric pathogens, even though the lagoon water is mixed with fresh water. Recirculating lagoon water to flush the feed alley pad, where cows stand while eating, to remove manure and using lagoon water to abate dairy dust in loafing pens and unimproved dairy roads is inconsistent with good environmental practice management.

Ambient and indoor particulate aerosols generated by dairies in the southern High Plains.

The objectives were to quantify and size ambient aerosolized dust in and around the facilities of 4 southern High Plains dairies of New Mexico and to determine where health of workers might be vulnerable to particulate aerosols, based on aerosol concentrations that exceed national air quality standards. Ambient dust air samples were collected upwind (background) and downwind of 3 dairy location sites (loafing pen boundary, commodity, and compost field). The indoor milking parlor, a fourth site, was monitored immediately upwind and downwind. Aerosolized particulate samples were collected using high-volume sequential reference air samplers, laser aerosol monitors, and cyclone air samplers. The overall (main effects and estimable interactions) statistical general linear model statement for particulate matter (PM(10); particulate matter with an aerodynamic diameter of up to 10 microm) and PM(2.5) resulted in a greater mean concentration of dust in the winter (PM(10) = 97.4 +/- 4.4 microg/m(3); PM(2.5) = 32.6 +/- 2.6 microg/m(3)) compared with the summer (PM(10) = 71.9 +/- 5.0 microg/m(3); PM(2.5) = 18.1 +/- 1.2 microg/m(3)). The upwind and downwind boundary PM(10) concentrations were significantly higher in the winter (upwind = 64.3 +/- 9.5 microg/m(3); downwind = 119.8 +/- 13.0 microg/m(3)) compared with the summer (upwind = 35.2 +/- 7.5 microg/m(3); downwind = 66.8 +/- 11.8 microg/m(3)). The milking parlor PM(10) and PM(2.5) concentration data were significantly higher in the winter (PM(10) = 119.5 +/- 5.8 microg/m(3); PM(2.5) = 55.3 +/- 5.8microg/m(3)) compared with the summer (PM(10) = 88.6.0 +/- 5.8 microg/m(3); PM(2.5) = 21.0 +/- 2.1 microg/m(3)). Personnel should be protected from high aerosol concentrations found at the commodity barn, compost field, and milking parlor during the winter.

Role of salivary protease activity in adherence of gram-negative bacilli to mammalian buccal epithelial cells in vivo.

Serious illness is accompanied by markedly increased susceptibility to colonization of the respiratory tract by gram-negative bacilli and an increase in the number of such organisms which adhere to regional epithelial cells during incubation in vitro. Trypsinization of cells from normal subjects causes a similar increase in bacillary adherence. We studied bacillary adherence to buccal cells in vitro, protease activity of upper respiratory secretions with a fibrin plate technique, and the amount of fibronectin on the surface of buccal cells with a direct radioimmunobinding assay. Among 10 patients seriously ill with acute respiratory failure bacillary adherence to buccal cells and protease activity in secretions were increased compared with controls and cell-surface fibronectin was decreased; all patients were colonized in vivo with gram-negative bacilli. These changes were persistent and 80% of the patients died. Serial determinations were made in eight patients undergoing coronary artery bypass surgery. Following surgery, protease activity and bacillary adherence increased and cell-surface fibronectin decreased; 38% of coronary artery bypass patients became colonized. In these uncomplicated patients the changes observed were transient, largely returning to normal by the third postoperative day. Increased protease activity of secretions and alterations in epithelial cell surfaces as reflected by loss of buccal cell-surface fibronectin occur swiftly after major illness and appear to underlie enhanced cell adherence of bacilli and colonization of the upper respiratory tract. These findings suggest new approaches to the prevention of nosocomial pneumonia.

An indoor air quality study of an alligator (Alligator mississippiensis) holding facility.

An environmental microbiologic investigation was conducted in an alligator (Alligator mississippiensis) holding facility in a zoo in the southeastern U.S. The facility had housed five alligators between March 1999 and February 2005. In the exhibit, one alligator died and all experienced poor health. It was hypothesized that environmental microbial contamination was associated with these issues. Samples were collected for fungal identification and quantification, microcystin analysis, and airborne mycotoxins. Analyses of air and water were conducted and an examination of the heating, ventilation, and air-conditioning system (HVAC) for design, maintenance, and operating issues was made. Two control sites, a facility for false gharials (Tomistoma schlegelii) and an off-site alligator breeding facility, were also tested. Morbidity and mortality records were examined for all sites. Results showed that, compared to the control sites, the test alligator facility and its HVAC system were extensively contaminated with a range of fungi. Nearly all sampled surfaces featured fungal growth. There were also significantly higher counts of Penicillium/Aspergillus-like and Chrysosporium-like spores in the air (P < 0.004). The design, maintenance, and operation of the HVAC system were all inadequate, resulting in poorly conditioned and mold-contaminated air being introduced to the facility. Morbidity records revealed solitary pulmonary disorders over time in three alligators, with one dying as a result. The other two alligators suffered from general malaise and a range of nonspecific symptoms. The control facilities had no morbidity or mortality issues. In conclusion, although no causal links could be demonstrated because of the nature of the morbidity data, environmental mold contamination appeared to be associated with the history of morbidity and mortality in the alligator exhibit.

Inhibition of rat alveolar macrophage phagocytic function by a Pseudomonas cepacia lipase.

The effects of purified Pseudomonas cepacia lipase on rat pulmonary alveolar function and morphology were examined. Lipase (2.5-20 micrograms/ml) adversely effected the phagocytic function of rat pulmonary alveolar macrophages in a dose-dependent manner. The lipase itself was not directly cytotoxic to these cells. Alveolar macrophages, in the absence of lipase, phagocytosed c. 35% of a given population of opsonised P. cepacia in 30 min when the ratio of bacteria:phagocyte was 10:1. Phagocytosis of P. cepacia by rat pulmonary alveolar macrophages was significantly reduced when the cells were either pre-incubated with the lipase or when phagocytosis occurred in the presence of the lipase. This was confirmed by transmission electronmicroscopy. These functional changes were associated with marked alterations of the macrophage morphology. Scanning electronmicroscopy showed that macrophages exposed to the P. cepacia lipase had fewer specialised surface structures and did not spread on plastic surfaces as well as untreated macrophages. The effects of the lipase were lost after heat inactivation, which indicates that the effects of the P. cepacia lipase were due to its enzymic activity. These results suggest that, if sufficient quantities of the enzyme are produced in vivo, lipase may be an important virulence factor for P. cepacia, allowing the organism to evade phagocytic cells.

Production of an extracellular toxic complex by various strains of Pseudomonas cepacia.

Six isolates of Pseudomonas cepacia, representing various serotypes of the organism and possessing similar degrees of virulence in mice, were examined for their production of an extracellular toxic complex (ETC) in vitro. This compound is lethal for mice and produces extensive lung pathology in rats; it is composed of a surface carbohydrate antigen, lipopolysaccharide and protein. All six isolates produced the ETC. The LD50 values for the six ETC preparations ranged from 395 micrograms for strain 61g to 1750 micrograms for strain 90ee. Only two of the six ETC preparations contained ketodeoxyoctonate detectable by the methods used, and these two were the most toxic. Rabbit antiserum to the ETC of a serotype D strain could significantly protect mice only against serotype D strains. Examination of the various phases of growth of P. cepacia showed that there was extracellular release of the ETC beginning in the early logarithmic phase and continuing through the late stationary phase. The presence of the ETC in the supernatant fluids was due to release of this material rather than to cell lysis. In addition, at least one strain of P. cepacia was shown to produce an alginic acid-like compound.

3-deoxy-D-manno-2-octulosonic acid in the lipopolysaccharide of various strains of Pseudomonas cepacia.

Six clinical isolates of Pseudomonas cepacia (representing the five serotypes of the organism) were examined for the presence of 3-deoxy-D-manno-2-octulosonic acid (KDO) in their lipopolysaccharide (LPS). Purified LPS was examined for the presence of KDO by the thiobarbituric acid (TBA) assay and by gas chromatography. All strains possessed KDO. One strain possessed KDO that was detectable by the TBA assay after mild acid hydrolysis with 0.04 M H2SO4 at 100 degrees C for 20 min. The other strains also possessed KDO but it was only demonstrable by the TBA assay after strong acid hydrolysis (4 M HCl for 60 min at 100 degrees C). All six purified LPS preparations were shown to possess KDO by two separate gas chromatography procedures. LPS isolated from the six strains of P. cepacia was toxic for mice.

The importance of extracellular antigens in Pseudomonas cepacia infections.

A clinical isolate of Pseudomonas cepacia from a cystic fibrosis patient was examined for its ability to produce extracellular toxic material. The organism was grown to stationary phase in a defined medium and toxic material was isolated by ultrafiltration, ion-exchange chromatography on DEAE-Sephacel and gel-filtration chromatography on Sepharose 4B. It consisted of a surface carbohydrate antigen, lipopolysaccharide and protein, and had an LD50 (when injected intraperitoneally into mice) of 395 +/- 20 micrograms. The toxicity appeared to be associated with the lipopolysaccharide portion of the complex, because boiling for 15 min and exposure to proteolytic enzymes had no effect on toxicity. However, saponification destroyed the toxicity of the compound. Studies employing radial immunodiffusion with the sera of mice infected with this organism demonstrated production of the complex in vivo at levels approaching those sufficient to produce death. When sublethal amounts of this complex were placed in the lungs of specific-pathogen-free rats, the lung pathology observed after 12, 24, 36 and 48 h was extensive. However, antibody generated in rabbits against this material could protect mice against the complex, as well as against challenge by the homologous organism. These data indicate that extracellular toxic material produced by P. cepacia may be responsible for the lethality and lung tissue destruction normally associated with an active pneumonia caused by this organism.

Efficacy of a subcutaneously administered, ultraviolet light-killed Pasteurella multocida A:3-containing bacterin against transthoracic challenge exposure in goats.

OBJECTIVE: To determine the effectiveness of Pasteurella multocida biovar A, serovar 3 (Pm A:3) killed by exposure to UV light and incorporated with a polyacrylate bead carrier as a vaccine. ANIMALS: 18 weanling male Spanish goats. PROCEDURE: Prospective, randomized controlled study with 3 treatment groups: positive-control (PC), negative-control (NC), and principal Pm A:3 bacterin (PA) groups. Six PC goats each received live Pm A:3 and polyacrylate beads twice, 22 days apart, by transthoracic injection into the left lung. Six NC goats each received only PA beads twice, 22 days apart, by transthoracic injection. Six principal goats each received Pm A:3 vaccine SC twice, 22 days apart. Fourteen days after the second vaccination, all goats were challenge exposed with live Pm A:3 by transthoracic injection into the right lung, and 4 days later they were euthanatized and necropsied. RESULTS: Mean volume of consolidated lung tissue at the challenge site was 1.75 cm3 for the PC group, 15.18 cm3 for the NC group, and 3.9 cm3 for the PA vaccine group. The NC group had a significantly (P < or = 0.002) larger mean volume of consolidated lung tissue than did the PC and PA groups after challenge exposure. CONCLUSIONS: The PA bacterin and the PC groups developed protective immunity against live Pm A:3 challenge exposure. An SC administered, UV light-killed, Pm A:3 bacterin induced protective immunity similar to that induced by virulent live Pm A:3 injected into the target organ, the lung.

Efficacy of Pasteurella haemolytica subunit antigens in a goat model of pasteurellosis.

The effectiveness of Pasteurella haemolytica biovar A, serovar 1 (Ph1) subunit vaccines was tested in goats, using challenge exposure by transthoracic injection. Twenty-two weanling male Spanish goats were randomly allotted to 4 groups. Six goats were given 2 transthoracic injections into the lung 18 days apart with live Ph1 impregnated in agar beads (positive controls). Six goats were not given injections (negative controls). Five goats were given 2 transthoracic injections into the lung 18 days apart with 4.6 mg of cytotoxin in agar beads. The remaining 5 goats were given 2 IM injections, 18 days apart, into the thigh with 4.6 mg of cytotoxin emulsified in incomplete Freund's adjuvant. Twenty-four days after the second injection, all goats were challenge-exposed to live Ph1 by transthoracic injection into the lung, and 4 days later, all goats were euthanatized and necropsied. Serum neutralizing anticytotoxin titer was measured throughout the experiment. Mean volume of consolidated lung tissue was 0.38 cm3 for the positive control group, 32 cm3 for the negative control group; 19 cm3 for the cytotoxin-lung group; and 88 cm3 for the cytotoxin-adjuvant-IM group. Only the positive control group was protected from Ph1 challenge exposure. The Ph1 cytotoxin subunit vaccine alone appeared to be ineffective, and the anticytotoxin titer was not correlated with protection. In a separate trial, 32 weanling male Spanish goats were randomly allotted to 5 groups. Each was given 2 transthoracic injections into the lung 22 days apart. Six goats were given Ph1 cytotoxin impregnated into agar beads; 6 were given Ph1 lipopolysaccharide impregnated in agar beads; 6 were given Ph1 capsule impregnated in agar beads. Six goats were given agar beads only (negative controls), and 6 were given live Ph1 impregnated into agar beads (positive controls). Twenty days after the second injection, all goats were challenge-exposed to live Ph1 by transthoracic injection into the lung, and 4 days later, all goats were euthanatized and necropsied. Mean volume of consolidated lung tissue was 0.14 cm3 for the positive control group, 7.59 cm3 for the negative control group, 11.21 cm3 for the cytotoxin group, 10.19 cm3 for the lipopolysaccharide group, and 1.6 cm3 for the capsule group. Again, only injection of live Ph1 (positive controls) induced solid protection; however, the capsule subunit vaccine induced partial protection against challenge exposure in this trial. Lipopolysaccharide and cytotoxin subunit vaccines were ineffective in protecting goats against challenge exposure with live Ph1.

Water quality in cattle feedyard playas in winter and summer.

OBJECTIVE: To determine the impact of feedyards on endotoxin concentration, fecal coliform count, and other water quality measurements during winter and summer in feedyard playas (shallow lakes). SAMPLE POPULATION: Water samples obtained from 7 feedyard playas and 3 nonfeedyard control playas. PROCEDURE: Surface water samples were collected from each playa and at various depths from 3 feedyard playas. Endotoxin concentrations, 22 water quality variables, and fecal coliform counts were determined in samples collected in summer and winter from various combinations of playas. RESULTS: Cattle numbers per feedyard ranged from 40,000 to 175,000 head/y. Mean endotoxin concentrations were significantly lower in control playas than in feedyard playas in winter and summer. Endotoxin concentration appeared to be homogenous at various water depths. Values for 20 of 22 water quality variables were higher in the feedyard playas than in control playas in winter and summer. In winter only, mean total fecal coliform concentration in feedyard playas was significantly greater than in control playas. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that feedyards have the potential to impact water quality in playas, and cattle should not be allowed access to them. Feedyard playa water should not be used under high pressure to settle dust in pens with cattle or to cool cattle, because aerosols containing pathogens and high concentrations of endotoxin are a health hazard for humans and cattle?

Efficacy of a subcutaneously administered, ultraviolet light-killed Pasteurella haemolytica A1-containing vaccine against transthoracic challenge exposure in goats.

OBJECTIVE: To determine the effectiveness of Pasteurella haemolytica biovar A, serovar 1 (Ph A1) killed by UV light and incorporated with an oil adjuvant or carriers. ANIMALS: 40 weaning male Spanish goats. PROCEDURE: Goats were randomly allotted to 1 of 6 treatment groups: 4 Ph A1 bacterins (agar beads, polyacrylate beads [PA], phosphate-buffered saline solution, Freund's incomplete adjuvant), live Ph A1 with polyacrylate beads (LiPhPA), and polyacrylate beads (UnVac). Each of 4 Ph A1 vaccines was administered SC twice, 21 days apart, to 1 of 4 groups; another group received only PA beads SC, and the last group received live Ph A1 with PA beads by transthoracic injection into the left lung. 14 days after the second vaccination, all goats were challenge exposed with live Ph A1 by transthoracic injection into the right lung, and 4 days later, all goats were euthanatized and necropsied. RESULTS: Mean volume of consolidated right lung tissue was 1.02 cm3 for the LiPhPA group, 168.1 cm3 for the UnVac group, 2.3 cm3 for the Freund's incomplete adjuvant bacterin group, 5.53 cm3 for the PA bacterin group, 9.01 cm3 for the agar beads bacterin group, and 7.51 cm3 for the phosphate-buffered saline solution bacterin group. Mean volume of consolidated lung tissue was significantly different between the UnVac group and the other 5 groups. CONCLUSION: The LiPhPA group and 4 bacterin groups developed protective immunity against live Ph A1 challenge exposure. CLINICAL RELEVANCE: An s.c. administered, UV light-killed Ph A1 bacterin induced protective immunity equal to that induced by virulent live Ph A1 injected into the target organ, the lung.

Conglutinin and immunoconglutinin titers in stressed calves in a feedlot.

OBJECTIVE: To determine whether increased conglutinin titers are evident in stressed calves that do not develop respiratory tract disease in feedlots, compared with respiratory tract disease, and to determine the increase in immunoconglutinin titers. ANIMALS: 101 mixed-breed beef calves. PROCEDURE: Calves were processed at 4 farms of origin and allowed to remain with their dams for another 100 days. Calves from each farm were brought to a centrally located order-buyer barn. In a feedlot, 101 calves were assigned to pens and observed daily for clinical signs of acute respiratory tract disease. When sick calves were detected, they were treated with antibiotics and isolated in a pen for 4 days. Conglutinin and immunoconglutinin titers were determined for all calves. RESULTS: During the 28-day study, 73 calves developed respiratory tract disease, whereas 28 calves remained healthy. Mean conglutinin titers differed significantly among calves from the 4 farms. Significant differences were not detected in conglutinin titers among calves on the basis of sex, morbidity, or vaccination status against Mannheimia haemolytica at each farm, the order-buyer barn, or the feedlot on days 8, 15, and 28 after arrival. Immunoconglutinin titers in calves differed significantly among farms and morbidity status. CONCLUSIONS AND CLINICAL RELEVANCE: Mean conglutinin titers in calves do not appear to be associated with the incidence of acute respiratory tract disease; however, increased immunoconglutinin titers appear to be associated with recovery of stressed calves from respiratory tract disease during the first 15 days after arrival in a feedlot.

Immune response to pulmonary injection of Pasteurella haemolytica-impregnated agar beads followed by transthoracic challenge exposure in goats.

A method of inducing Pasteurella haemolytica serotype 1 (Ph1) lung infection in goats, using low numbers of bacteria and without impairing host immunity, was developed. Two trials were conducted. Results of trial 1, using 10 principals (Ph1 agar beads) and 6 controls (agar beads alone), indicated that Ph1 organisms imbedded in agar beads could survive host lung defenses for 32 days. Results of trial 2 indicated that lung immunity in the inoculated goats (principals) was high and they were more protected than controls against a transthoracic challenge of Ph1 (1.18 x 10(7) colony-forming units) injected into a lung of each goat on posttreatment day 35. When comparing challenge-exposed principals with controls, the controls developed rectal temperatures above normal for a longer time, duration of anorexia was longer, and signs of depression were seen. The controls developed large areas of consolidated lung tissue, more Ph1 isolates were recovered from nasal turbinates and lung tissue, and higher Ph1 concentrations were found in the lungs. The serum Ph1 indirect hemagglutination antibody titers in the principals of both trials increased, compared with titers in controls. Principal goats in trial 2 had higher Ph1 indirect hemagglutination antibody titers after injection of Ph1-impregnated agar beads and less severe lung lesions after challenge exposure than did controls. The small pneumonic consolidated lesions in the principals, compared with extensive lesions in controls after Ph1 challenge exposure, indicated a high degree of immunity after exposure to Ph1 organisms imbedded in agar beads.

The presence of fungi associated with sick building syndrome in North American zoological institutions.

A total of 110 sites from five zoological institutions were examined to determine whether fungi associated with sick building syndrome (SBS) were prevalent in the exhibits or night-time holding facilities and to investigate whether the presence of these organisms was associated with declining breeding rates or increases in morbidity and mortality (or both). Each site was sampled with an Andersen two-stage air sampler using Sabourauds dextrose agar media and a Burkard personal volumetric air sampler. Suspect surfaces were also sampled. High levels of airborne Penicillium chrysogenum, a fungal species associated with poor indoor air quality, were recovered from 16 sites out of all five institutions. Five culturable growth sites of Stachybotrys chartarum, a species strongly associated with SBS and commonly known as "black mold," were recovered from surfaces at two institutions. A wide range of other fungal species was recovered in low numbers from all institutions. A Fisher exact test analysis showed a significant nonrandom association between high levels of P. chrysogenum and sites with records of poor animal health. This study indicated that significant numbers of airborne fungi associated with SBS and poor indoor air quality are present in zoological institutions and that they could affect animal health and reproduction rates and zoo staff.

Heat stability of chaetoglobosins A and C.

Chaetomium globosum is commonly found in water-damaged buildings and produces the mycotoxins chaetoglobosin A and chaetoglobosin C (Ch-A and Ch-C, respectively). While attempting to purify Ch-A and Ch-C, we observed that these mycotoxins were broken down after heating. The objective of this study was to determine the temperature and the amount of time necessary to break down Ch-A and Ch-C. We demonstrated that the amounts of Ch-A were significantly reduced when exposed to 75 degrees C for 24 h and 100 degrees C for 90, 120, or 150 min. Under the same conditions, the levels of Ch-C were also lower (although not significantly). At 175 degrees C, no Ch-A was detected after 15 min and Ch-C was significantly reduced after 30 min. Our findings will aid other researchers who work with these mycotoxins in the future.

Detection of airborne Stachybotrys chartarum macrocyclic trichothecene mycotoxins in the indoor environment.

The existence of airborne mycotoxins in mold-contaminated buildings has long been hypothesized to be a potential occupant health risk. However, little work has been done to demonstrate the presence of these compounds in such environments. The presence of airborne macrocyclic trichothecene mycotoxins in indoor environments with known Stachybotrys chartarum contamination was therefore investigated. In seven buildings, air was collected using a high-volume liquid impaction bioaerosol sampler (SpinCon PAS 450-10) under static or disturbed conditions. An additional building was sampled using an Andersen GPS-1 PUF sampler modified to separate and collect particulates smaller than conidia. Four control buildings (i.e., no detectable S. chartarum growth or history of water damage) and outdoor air were also tested. Samples were analyzed using a macrocyclic trichothecene-specific enzyme-linked immunosorbent assay (ELISA). ELISA specificity was tested using phosphate-buffered saline extracts of the fungal genera Aspergillus, Chaetomium, Cladosporium, Fusarium, Memnoniella, Penicillium, Rhizopus, and Trichoderma, five Stachybotrys strains, and the indoor air allergens Can f 1, Der p 1, and Fel d 1. For test buildings, the results showed that detectable toxin concentrations increased with the sampling time and short periods of air disturbance. Trichothecene values ranged from <10 to >1,300 pg/m3 of sampled air. The control environments demonstrated statistically significantly (P < 0.001) lower levels of airborne trichothecenes. ELISA specificity experiments demonstrated a high specificity for the trichothecene-producing strain of S. chartarum. Our data indicate that airborne macrocyclic trichothecenes can exist in Stachybotrys-contaminated buildings, and this should be taken into consideration in future indoor air quality investigations.

Detection of airborne Stachybotrys chartarum macrocyclic trichothecene mycotoxins on particulates smaller than conidia.

Highly respirable particles (diameter, <1 microm) constitute the majority of particulate matter found in indoor air. It is hypothesized that these particles serve as carriers for toxic compounds, specifically the compounds produced by molds in water-damaged buildings. The presence of airborne Stachybotrys chartarum trichothecene mycotoxins on particles smaller than conidia (e.g., fungal fragments) was therefore investigated. Cellulose ceiling tiles with confluent Stachybotrys growth were placed in gas-drying containers through which filtered air was passed. Exiting particulates were collected by using a series of polycarbonate membrane filters with decreasing pore sizes. Scanning electron microscopy was employed to determine the presence of conidia on the filters. A competitive enzyme-linked immunosorbent assay (ELISA) specific for macrocyclic trichothecenes was used to analyze filter extracts. Cross-reactivity to various mycotoxins was examined to confirm the specificity. Statistically significant (P < 0.05) ELISA binding was observed primarily for macrocyclic trichothecenes at concentrations of 50 and 5 ng/ml and 500 pg/ml (58.4 to 83.5% inhibition). Of the remaining toxins tested, only verrucarol and diacetylverrucarol (nonmacrocyclic trichothecenes) demonstrated significant binding (18.2 and 51.7% inhibition, respectively) and then only at high concentrations. The results showed that extracts from conidium-free filters demonstrated statistically significant (P < 0.05) antibody binding that increased with sampling time (38.4 to 71.9% inhibition, representing a range of 0.5 to 4.0 ng/ml). High-performance liquid chromatography analysis suggested the presence of satratoxin H in conidium-free filter extracts. These data show that S. chartarum trichothecene mycotoxins can become airborne in association with intact conidia or smaller particles. These findings may have important implications for indoor air quality assessment.