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PubMed1985

Comparison of the airborne survival of calf rotavirus and poliovirus type 1 (Sabin) aerosolized as a mixture.

A mixture of a cell culture-adapted strain (C-486) of calf rotavirus and poliovirus type 1 (Sabin) was prepared in tryptose phosphate broth containing 0.1% uranine (physical tracer) and antifoam at a final concentration of 0.001%. By using a six-jet Collison nebulizer, the mixture was aerosolized into a 300-liter stainless-steel rotating (4 rpm) drum. The temperature of the air inside the drum was kept at 20 +/- 1 degrees C, and the virus aerosols were held at the following three levels of relative humidity (RH): low (30 +/- 5%), medium (50 +/- 5%), and high (80 +/- 5%). An all-glass impinger, containing 10.0 ml of tryptose phosphate broth with antifoam, was used to collect samples of air from the drum. Both viruses were propagated and quantitated in MA-104 cells. The calf rotavirus was found to survive well at mid-range RH, where 60% of the infectious virus could be detected even after 24 h of virus aerosolization. At the low RH, the half-life of the infectious rotavirus was ca. 14 h. On the other hand, no infectious poliovirus could be recovered from the drum air at the low and medium RH. At the high RH, more than 50% of the infectious rotavirus became undetectable within 90 min of aerosolization. In contrast to this, the half-life of the poliovirus at the high RH was about 10 h. These data, based on the aerosolization of virus mixtures, therefore suggest that there is a pronounced difference in the way RH influences the airborne survival of these two types of viruses held under identical experimental conditions.

Aerosols↗
PubMed1985

Aerosols containing Legionella pneumophila generated by shower heads and hot-water faucets.

Shower heads and hot-water faucets containing Legionella pneumophila were evaluated for aerosolization of the organism with a multistage cascade impaction air sampler. Air was collected above two shower doors and from the same rooms approximately 3 ft (91 cm) from the shower doors while the hot water was running. Low numbers (3 to 5 CFU/15 ft3 [0.43 m3] of air) of L. pneumophila were recovered above both shower doors, but none was recovered from the air in either room outside the shower door. Approximately 90% (7 of 8 CFU) of the L. pneumophila recovered were trapped in aerosol particles between 1 and 5 micron in diameter. Air was collected 1 to 3 ft (30 to 91 cm) from 14 sinks while the hot water was running. Low numbers (1 to 5 CFU/15 ft3 of air) were recovered from 6 of 19 air samples obtained. Approximately 50% (6 of 13 CFU) of the organisms recovered were trapped in aerosol particles between 1 and 8 microns in diameter. Shower heads and hot-water taps containing L. pneumophila can aerosolize low numbers of the organism during routine use. The aerosol particle size is small enough to penetrate to the lower human respiratory system. Thus, these sites may be implicated as a means of transmission of L. pneumophila from potable water to the patient.

Aerosols↗
PubMed1990

Survival of bacteria during aerosolization.

One form of commercial application of microorganisms, including genetically engineered microorganisms is as an aerosol. To study the effect of aerosol-induced stress on bacterial survival, nonrecombinant spontaneous antibiotic-resistant mutants of four organisms, Enterobacter cloacae, Erwinia herbicola, Klebsiella planticola, and Pseudomonas syringae, were sprayed in separate experiments in a greenhouse. Samples were collected over a distance of 15 m from the spray site for enumeration. Spores of Bacillus subtilis were used as tracers to estimate the effects of dilution on changes in population over distance. Viable counts of P. syringae, Enterobacter cloacae, and K. planticola decreased significantly over a distance of 15 m. Erwinia herbicola showed no significant decline in counts over the same distance. The degree of survival of P. syringae during aerosolization was dependent on ambient environmental conditions (i.e., temperature, relative humidity), droplet size of the aerosol, and prior preparative conditions. Survival was greatest at high relative humidities (70 to 80%) and low temperatures (12 degrees C). Survival was reduced when small droplet sizes were used. The process of washing the cells prior to aerosolization also caused a reduction in their survival. Results from these experiments will be useful in developing sound methodologies to optimize enumeration and for predicting the downwind dispersal of airborne microorganisms, including genetically engineered microorganisms.

Aerosols↗
PubMed1993

Influence of temperature and relative humidity on the survival of Chlamydia pneumoniae in aerosols.

The survival of Chlamydia pneumoniae in aerosols was investigated by using a chamber with a capacity of 114.5 liters. We injected 5 x 10(7) inclusion-forming units (IFU) of C. pneumoniae in aerosols with a droplet size of 3 to 5 microns. Samples were taken after 30 s and every 1 min thereafter. The survival of C. pneumoniae was measured at four temperatures (8.5, 15, 25, and 35 degrees C) and at three different relative humidities (RH) of 5, 50, and 95% for each temperature. The survival rates of Streptococcus pneumoniae, Streptococcus faecalis, Klebsiella pneumoniae, Chlamydia trachomatis LGV2, and cytomegalovirus were also determined at 25 degrees C and 95% RH and compared with that of C. pneumoniae. At the mentioned temperatures and RH, a rapid decrease of C. pneumoniae IFU was observed in the first 30 s. After this the decrease in the number of IFU was more gradual. The survival of C. pneumoniae in aerosols were optimal at 15 to 25 degrees C and 95% RH; it was good compared with those of other microorganisms. A lower death rate was observed only in S. faecalis. In C. trachomatis, the death rate during the first 30 s was higher than that in C. pneumoniae (85 and 53.3%, respectively). After the first 30 s, the death rates in the two organisms were identical. It was concluded that transmission of C. pneumoniae via aerosols was possible. There is probably a direct transmission from person to person, taking into account the relatively short survival period of C. pneumoniae in aerosols.

Aerosols↗
PubMed1965

Effects of oxygen on aerosolized Serratia marcescens.

Suspensions of Serratia marcescens (ATCC strain 14041) in water were aerosolized in a rotating drum in the presence of various concentrations of oxygen. The colony-forming ability of aerosolized organisms was rapidly destroyed by contact with 0.25% or more oxygen at 40% relative humidity (RH) and 25 C, but was almost unimpaired for at least 5 hr in nitrogen containing not more than 10 ppm of oxygen. Completely hydrated organisms were insensitive to oxygen at pressures up to 100 psi for 4 hr. No loss in viability occurred in aerosols of washed cells in air at 97% RH. It is proposed that dehydration of the aerosolized cell results in sensitization to lethal effects of oxygen, but is not the primary cause of death. Mn(++), Co(++), glycerol, and thiourea enhanced the biological stability of aerosols in air. Numerous similarities between the effects of oxygen in this system and in systems using freeze-dried or irradiated organisms or cell-free enzymes support the hypothesis that closely related mechanisms are involved.

Aerosols↗
PubMed1968

Aerosols of mycoplasmas, L forms, and bacteria: comparison of particle size, viability, and lethality of ultraviolet radiation.

Aerosols of microorganisms were tested for particle size by use of an Andersen sampler. Mycoplasma aerosols had an average count median diameter (CMD) of 2.1 +/- 0.5 mu. Staphylococcus aureus L forms gave an average CMD of 4.6 +/- 1.7 mu; the diphtheroid L form, a CMD of 3.4 +/- 0.3 mu. Escherichia coli had a CMD of 5.4 +/- 2.5 mu; Neisseria sicca, 3.3 +/- 0.5 mu; N. meningitidis, 3.4 +/- 0.2 mu. S. aureus ATCC 6538, the parent strain of the L form, yielded a CMD of 3.9 +/- 1.2 mu. Candida albicans gave an average CMD of 5.9 +/- 1.4 mu. All organisms tested survived aerosolizing and could be recovered in viable form for at least 1 hr. Ultraviolet radiation at 2,537 A destroyed the bacteria and mycoplasmas instantaneously, and destroyed 87% of the L forms of S. aureus, 69% of the diphtheroid L form, and 98% of the C. albicans cells. After irradiation, viable particles of the L form and C. albicans aerosols were consistently larger, indicating that clumping led to survival. Submicron size particles were found in aerosols of all species tested except C. albicans.

Aerosols↗
PubMed1968

Direct method for determining the viability of a freshly generated mixed bacterial aerosol.

A direct method was developed to determine the viability of a freshly generated mixed bacterial aerosol. A mixed suspension of (32)P-labeled Staphylococcus aureus and (35)S-labeled Proteus mirabilis was nebulized, and the aerosol was collected and separated according to particle size with an Andersen sampler. Quantitative and qualitative bacteriological and radioisotopic techniques were used to obtain ratios of bacterial to radioactive counts for each organism in samples of the nebulizer suspension and aerosol. Loss of viability was calculated from the change that occurred between the ratio of the nebulizer suspension and the ratio of the aerosol. The viability of S. aureus was unaffected by aerosolization, whereas the viability of P. mirabilis declined by 20 to 60% and was inversely proportional to particle size. The advantages of this method over present indirect methods, as well as potential applications of the method, are discussed.

Aerosols↗
PubMed1971

Effect of simulated solar radiation and sodium fluorescein on the recovery of Venezuelan equine encephalomyelitis virus from aerosols.

Almost 90% of the Trinidad strain of Venezuelan equine encephalomyelitis (VEE) virus survived for 1 hr after aerosolization into a dark environment at 30% relative humidity (RH), and 78% survived for 1 hr at 60% RH. After exposure to simulated solar radiation (584 mcal per cm(2) per min) 0.02% of the aerosolized virus survived for 1 hr at 30% RH and 0.006% survived for 1 hr at 60% RH. When 1.0 mg of sodium fluorescein per ml was added to suspensions prior to aerosol dissemination (to determine physical loss of aerosol), no virus was detected after 30 min at either RH upon irradiation. Sodium fluorescein also exhibited some toxicity (31% survival at 60 min) for nonirradiated aerosols of VEE virus at 60% RH; no effect was noted at 30%.

Aerosols↗
PubMed1971

Aerosol survival of Pasteurella tularensis disseminated from the wet and dry states.

The aerosol survival in air and in nitrogen was measured for Pasteurella tularensis live vaccine strain, disseminated from the wet and dry states. The results showed that most of the loss of viability occurred in less than 2 min of aerosol age, i.e., a rapid initial decay followed by a much slower secondary decay. In nitrogen and air, minimum survival occurred at 50 to 55% relative humidity (RH) for wet dissemination and at 75% RH for dry dissemination. This shift indicated that aerosols produced by wet and dry dissemination were not equivalent and suggested that survival might not be related to bacterial water activity or content. The results showed that rehydration is the key process with regard to survival, but that lysis on rehydration is not a primary death mechanism. The effects of oxygen were complex because it could be either protective or toxic, depending upon other conditions. The protective action of oxygen was through an effect on the spent culture suspending fluid. The latter contained a toxic component, the activity of which is suppressed by oxygen; possibly the component is pumped away during freeze-drying. A toxic effect of oxygen was not found in the presence of spent culture media because the toxicity of the latter masks such an effect. With other bacterial suspending fluids, oxygen was shown to be toxic at low RH. Similar effects with regard to oxygen toxicity were also found with a laboratory strain of P. tularensis. Differences in oxygen toxicity for aerosols generated from the wet and dry states also suggest that bacterial water content and activity do not control aerosol survival.

Aerosols↗
PubMed1980

Aerosol stability and respiratory infectivity of japanese B encephalitis virus.

Experiments were conducted to examine the aerosol stability and respiratory infectivity of Japanese B encephalitis virus. At 75 degrees F (about 24 degrees C), survival of the virus as aerosol was inversely related to relative humidity. After correction for physical decay, the mean virus half-lives of the virus were 28, 38, and 62 min at relative humiditis of 80, 55, and 30%, respectively. Virus recoveries as aerosol at 4 min aftr dissemination generally exceeded the theoretical limit of 100%, based on the amount disseminated, to suggest that the process of dissemination operated to deagglomerate or release bound virus from the tissue cells in suspension. Swiss-ICR mice and golden Syrian hamsters were highly susceptible to lethal infections after respiratory challenge. Hartley strain guinea pigs and Fisher-Dunning rats, although infected, based on seroconversion observations, survived the infections. Deaths occurred in squirrel monkeys only after exposure to a high aerosol dose of virus (10(6.0) plaque-forming units). Studies of the virus concentration dynamics and histopathological findings in mouse tissues after aerosol challenge supported a hypothesis for direct transport of virus across the foramina of the cribriform plate to the tissues of the central nervous system to produce primary encephalitis.

Aerosols↗
PubMed1986

Development of an aerosol model of murine respiratory mycoplasmosis in mice.

Animal models of murine respiratory mycoplasmosis due to Mycoplasma pulmonis provide excellent opportunities to study respiratory disease due to an infectious agent. The purpose of the present study was to develop and characterize an aerosol model for the production of murine respiratory mycoplasmosis in mice. The exposure of mice for 30 min to aerosols generated with a DeVilbiss 45 nebulizer in a nose-only inhalation chamber consistently reproduced typical lesions. The chamber was operated with a nebulizer air flow of 5.3 liters/min at 5.0 lb/in and a diluting air flow of 20 liters/min, with the nebulizer containing 5 ml of a suspension of viable M. pulmonis organisms (a concentration between 6 X 10(5) to 6 X 10(10) CFU/ml). Infective aerosol particles of less than a 4.0-micron median aerodynamic diameter with a geometric standard deviation of approximately 2.0 reached the lungs and were evenly distributed among the different lung lobes. A minimum 1.5-log loss of viability in the M. pulmonis suspension was demonstrated. With the exception of the 50% lethal dose, all of the parameters previously established by intranasal inoculation could be examined with the aerosol model. The major advantages of the aerosol model were excellent reproducibility of exposure (both between different experiments and between animals in a given experiment), the avoidance of anesthetization, and the ability to immediately deposit the majority of the organisms in the lung. The only disadvantage was the requirement for large volumes of mycoplasmal cultures.

Aerosols↗
PubMed2005

Human leukocyte antigen-DQ8 transgenic mice: a model to examine the toxicity of aerosolized staphylococcal enterotoxin B.

Staphylococcal enterotoxins (SEs) belong to a large group of bacterial exotoxins that cause severe immunopathologies, especially when delivered as an aerosol. SEs elicit the release of lethal amounts of cytokines by binding to major histocompatibility complex (MHC) class II and cross-linking susceptible T-cell receptors. Efforts to develop effective therapeutic strategies to protect against SEs delivered as an aerosol have been hampered by the lack of small animal models that consistently emulate human responses to these toxins. Here, we report that human leukocyte antigen-DQ8 (HLA-DQ8) transgenic (Tg) mice, but not littermate controls, succumbed to lethal shock induced by SEB aerosols without potentiation. Substantial amounts of perivascular edema and inflammatory infiltrates were noted in the lungs of Tg mice, similar to the pathology observed in nonhuman primates exposed by aerosol to SEB. Furthermore, the observed pathologies and lethal shock correlated with an upsurge in proinflammatory cytokine mRNA gene expression in the lungs and spleens, as well as with marked increases in the levels of proinflammatory circulating cytokines in the Tg mice. Unlike the case for littermate controls, telemetric evaluation showed significant hypothermia in Tg mice exposed to lethal doses of SEB. Taken together, these results show that this murine model will allow for the examination of therapeutics and vaccines developed specifically against SEB aerosol exposure and possibly other bacterial superantigens in the context of human MHC class II receptors.

Aerosols↗
PubMed1995

A non-electrostatic spacer for aerosol delivery.

A pear shaped non-electrostatic spacer, composed of steel with a volume of 250 ml and equipped with a facemask containing integrated inlet and outlet valves for inspiration and expiration, was compared with three plastic spacers. The plastic spacers were primed with repeated puffs from a budesonide pressurised metered dose inhaler (p-MDI) to minimise the electrostatic charge on the plastic. The procedure prolonged the half life (t1/2) of the aerosol in the Nebuhaler from nine to 32 seconds. A normal cleaning procedure reduced the aerosol t1/2 back to baseline. The t1/2 of the aerosol in the metal spacer was 27 seconds and independent of the use of p-MDI. In vitro the maximum dose of budesonide from a p-MDI, expressed as a percentage of the nominal dose, was 56% from the non-electrostatic spacer, 61% from the Nebuhaler, 45% from the Babyhaler, and 30% from the AeroChamber. In 124 children, age 6 months to 6 years, suspected to have asthma the non-electrostatic spacer delivered a mean total dose of budesonide aerosol of 39% of the nominal dose, which was significantly higher than the Babyhaler (28%), the Nebuhaler (21%), and the AeroChamber (19%). These differences were most pronounced in children younger than 4 years. The improved dose delivery from the small volume non-electrostatic spacer is probably related to the non-electrostatic spacer material and the valves which assured unidirectional airflow from the spacer without adding any dead space in the inspiratory channel. The non-electro-static spacer should improve the cost effectiveness of aerosol treatment and, as the counteracting effects of proming and recharging of the plastic from cleaning are avoided, should deliver a more reliable dose.

Aerosols↗
PubMed2000

Lung deposition of aerosol--a comparison of different spacers.

AIMS: To investigate (1) aerosol lung deposition obtained from two small volume conventional spacers (Babyhaler and Aerochamber) and a home made spacer (modified 500 ml plastic cold drink bottle); (2) the effect of using a face mask or mouthpiece; and (3) the relation between age and pulmonary deposition. METHODS: Lung deposition of aerosolised technetium-99m DTPA inhaled via spacer was measured in 40 children aged 3-7 years with stable asthma. Each patient performed sequential randomly assigned inhalations using two spacers. Three studies were performed: Babyhaler compared to Aerochamber (with facemasks); Babyhaler with facemask compared to Babyhaler with mouthpiece; and Babyhaler with mouthpiece compared to a 500 ml bottle. RESULTS: Median lung aerosol deposition from a Babyhaler and Aerochamber with masks were similar (25% v 21%, p = 0.9). Aerosol lung deposition from a Babyhaler with mask compared to a Babyhaler with mouthpiece was equivalent (26% v 26%, p = 0.5). Lung deposition was higher from a 500 ml bottle compared to a Babyhaler in both young (25% v 12.5%, p = 0.005) and older children (42% v 22.5%, p = 0.003). A notable reduction in pulmonary deposition occurred at 50 months of age. CONCLUSION: A Babyhaler or Aerochamber produce equivalent lung deposition of aerosol. There is no difference in lung deposition when a mask or mouthpiece is used. A modified 500 ml plastic bottle produces greater pulmonary aerosol deposition than a conventional small volume spacer.

Administration, Inhalation↗
PubMed1999

Measurement of human exposure to biologically relevant fractions of inhaled aerosols.

Aerosol sampling has evolved with changes in technology and our understanding of the importance of assessing the biologically relevant fractions of the total aerosol. During the past decade there has been international agreement on the definitions for the inhalable, thoracic, and respirable fractions and instruments have been developed to collect samples according to these conventions. These measurement techniques are now well established in the workplace and are increasingly being applied to assessments of non-occupational exposure, as the practical difficulties in obtaining samples over 24 hours have been solved. It is argued that multiple aerosol size fractions should be measured for hazardous substances--such as inorganic lead--in which inhaled material may either be absorbed in the alveoli (respirable) or cleared from the ciliated airways in the lung to the gut and then absorbed (thoracic and extrathoracic). Such measurements should improve the evaluation of the risk for inhaled lead, particularly for non-occupational exposure of children. Also, passive aerosol sampling techniques may enable measurements of non-occupational exposure to be made over several weeks and this would also help improve the reliability of the risk evaluation for aerosol toxicants with a long biological half life. However, further development of these techniques is required if they are to be practicable and biologically relevant.

Aerosols↗
PubMed1984

Improvement of pressurised aerosol deposition with Nebuhaler spacer device.

The effect on aerosol deposition from a pressurised metered dose inhaler of a 750 cm3 spacer device with a one way inhalation valve (Nebuhaler, Astra Pharmaceuticals) was assessed by means of an in vivo radiotracer technique. Nine patients with obstructive lung disease took part in the study. The pattern of deposition associated with use of a metered dose inhaler alone was compared with that achieved with the spacer used both for inhalation of single puffs of aerosol and for inhalation of four puffs actuated in rapid succession and then inhaled simultaneously. On each occasion there was a delay of 1 s between aerosol release and inhalation, simulating poor inhaler technique. With the metered dose inhaler alone, a mean (SEM) 8.7 (1.8)% of the dose reached the lungs and 80.9 (1.9)% was deposited in the oropharynx. With single puffs from the spacer 20.9 (1.6)% of the dose (p less than 0.01) reached the lungs, only 16.5 (2.3)% (p less than 0.01) was deposited in the oropharynx, and 55.8 (3.1)% was retained within the spacer itself. With four puffs from the spacer 15.2 (1.5)% reached the lungs (p = 0.02 compared with the metered dose inhaler alone, p less than 0.01 compared with single puffs from the spacer), 11.4 (1.2)% was deposited in the oropharynx, and 67.5 (1.8)% in the device itself. It is concluded that the spacer device gives lung deposition of metered dose aerosols comparable to or greater than a correctly used inhaler and oropharyngeal deposition is greatly reduced. The spacer should be used preferably for the inhalation of single puffs of aerosol but may also be used for the inhalation of up to four puffs actuated in rapid succession and then inhaled simultaneously.

Adult↗
PubMed1985

Dose-response effect of sodium cromoglycate pressurised aerosol in exercise induced asthma.

The effects of 2, 10, and 20 mg of sodium cromoglycate delivered by aerosol were compared with those of placebo in a double blind study in 11 patients with extrinsic and exercise induced asthma. The effect of nebulised sodium cromoglycate delivered through a Wright nebuliser (estimated dose 12 mg) was also studied. Patients exercised on a treadmill for six to eight minutes at submaximal work loads on five days, 30 minutes after inhaling placebo or sodium cromoglycate. The FEV1 was recorded before treatment, before exercise, and up to 30 minutes after exercise. Mean baseline values of FEV1 before and after placebo or sodium cromoglycate did not differ significantly on the five days. After exercise the mean (SEM) maximal percentage fall in FEV1 after placebo; 12 mg sodium cromoglycate nebuliser solution; and 2, 10, and 20 mg sodium cromoglycate aerosol were 31.1 (3.8); 9.4 (2.1); and 19.4 (4.6), 13.7 (3.5), and 9.4 (1.9). Sodium cromoglycate inhibited exercise induced asthma at all doses used; the protective effect of the aerosol increased from 2 to 20 mg. The protective effect of 20 mg sodium cromoglycate aerosol was similar to that seen with 12 mg nebulised solution. Our results suggest that the effect of sodium cromoglycate aerosol in exercise induced asthma is dose related.

Adult↗
PubMed1995

Differences in aerosol output and airways responsiveness between the DeVilbiss 40 and 45 hand held nebulisers.

BACKGROUND: The DeVilbiss 40 glass hand held nebulisers have been widely used for airways responsiveness testing in epidemiological surveys of asthma. These nebulisers have been superseded in some recent studies by the DeVilbiss 45 plastic hand held nebulisers with the assumption that they are interchangeable. This study compared the aerosol outputs of the DeVilbiss 40 and DeVilbiss 45 nebulisers and investigated whether there was any difference in the in vivo measurements of airways responsiveness when using the two nebuliser types. METHODS: The aerosol output of six DeVilbiss 40 and six DeVilbiss 45 nebulisers was calculated by weight loss per actuation, the usual method of calibrating nebuliser output, and compared with the true amount of aerosol obtained measured by a flouride tracer technique. Airways responsiveness was measured twice in 13 asthmatic patients under identical conditions by the Yan protocol using DeVilbiss 40 and 45 nebulisers in random order. RESULTS: Weight loss overestimated the true aerosol output of both types of nebulisers. Weight loss was similar for the DeVilbiss 40 and 45 nebulisers but the true aerosol output of the DeVilbiss 45 was nearly twice that of the DeVilbiss 40 nebuliser. The geometric mean PD20 values with the DeVilbiss 40 nebuliser was a mean 1.7 doubling doses of histamine higher than that obtained with the DeVilbiss 45 nebuliser. CONCLUSIONS: The DeVilbiss 40 and 45 nebulisers should not be used interchangeably for airways responsiveness testing merely because their outputs based on weight loss are similar. Artefactual differences in the prevalence rates of airways responsiveness could occur in longitudinal studies if a change was inadvertently made from using DeVilbiss 40 to DeVilbiss 45 nebulisers.

Adult↗