Characterization of indoor bioaerosols from a hospital ward in a tropical setting

Objectives

Study was conducted to assess whether temporal variation exists in airborne microbial concentrations of a hospital ward (west-Chennai, India) using active and passive methods, and characterise the microorganisms.

Methods

Air samples (duplicates) were collected simultaneously using exposed-plate, impingement (BioSampler) and filtration (personal sampling filter cassette loaded with gelatin filter) methods over different periods of the year. Bacterial plates were incubated at 37°C and observed for growth after 48h; fungal plates were incubated at 25°C and 37°C and observed upto 7 days. Microorganisms were identified using standard microbiological procedures.

Results

Microbial loads were found to vary with the sampling method. Concentrations of bacteria were higher (exposed-plate: 45–150 CFU/plate; impingement: 1.12E+03–1.6856E+05 CFU/m³; filtration: 3.788E+03−1.91111E+05 CFU/m³) than fungi (exposed-plate: 0–13 CFU/plate; impingement: 0–3.547E+03 CFU/m³; filtration: 0–1.515E+04 CFU/ m³). Coagulase-negative Staphylococci and Micrococci were the predominant Gram-positive cocci in active and passive samples. Enterobacter and Pseudomonas were the predominant Gram-negative bacilli. Among fungi, Aspergillus niger was isolated throughout the year. There was no significant temporal variation in airborne microbial loads irrespective of methods.

Conclusions

Exposed-plate method was found to capture microorganisms efficiently with little variation in duplicate samples, suggesting its use in hospitals for preliminary assessment of indoor air quality and determine pathogenic microorganisms due to particle fall-out.     

Metalworking fluid bioaerosols at selected workplaces in a steelworks

BACKGROUND: Exposure to metalworking fluid (MWF) aerosols has been shown to be associated with a variety of respiratory and skin diseases of workers. METHODS: Measurements of particulate aerosols, bacterial bioaerosol, and endotoxins and 3-hydroxy fatty acids (3-OH FAs) content in water-based and straight oil MWFs were done during an 8 hr work shift in the grindery and oil basement sections of a steelworks located in Upper Silesia, Poland. RESULTS: Particulate aerosol concentrations were below NIOSH recommended occupational exposure level. Differences in concentration and taxonomical composition of airborne bacteria between grindery and oil basement were found, due to the more aggressive creation of oil mist during machining operations and different MWF characteristics, which favor growth of different bacterial strains. CONCLUSIONS: The GC-MS analysis of 3-OH FAs as a marker of endotoxin contamination of the MWF and of the air seems to be a promising tool for evaluation of occupational exposure to bacterial bioaerosols.     

Occupational endotoxin-exposure and possible health effects on humans

BACKGROUND: Endotoxins are commonly found at workplaces where large amounts of bioaerosols are generated. In Germany, especially since the Ordinance on Safety and Health Protection related to work involving biological agents (Biostoff-Verordnung) became effective (1999), threshold limit values are widely discussed. Up to the present, endotoxin values are measured with non-uniform methods and therefore values are of limited benefit for classification of exposure groups. In Germany there is no threshold limit value for endotoxin. METHODS: Relevant literature of the last 20 years was selected from Medline and discussed. RESULTS: In this review we focused on the impact of endotoxin exposure on human health with special respect to the measurements on workplace and methodological aspects of endotoxin determination. Methods for sampling and endotoxin determination have to be validated, optimized, and standardized first. CONCLUSION: The adverse health effects of endotoxins are known, standardization of measurements is a necessary goal and protection measures should be established immediately.     

Respiratory Drug Delivery X

There were ～ 700 delegates who attended Respiratory Drug Delivery X (RDD-X) at the Boca Raton Resort and Club in Boca Raton, Florida, between the 24th and 27th April 2006. Participants from North America, Europe and many other parts of the world came together to hear a series of invited podium presentations covering the latest scientific developments in pulmonary and nasal drug delivery, along with regulatory and quality control issues. A total of 150 proffered posters were also presented, and a Technology Exhibition involved the products of 78 companies. The conference also provided unparalleled networking opportunities. The proceedings of RDD-X will prove to be an invaluable resource for years to come.     

Eggshells as a source for occupational exposure to airborne bacteria in hatcheries

Occupational exposure to high concentrations of airborne bacteria in poultry production is related to an increased risk of respiratory disorders. However, potential sources and formation of hatchery bioaerosols are rarely characterized. In this study, bacterial multiplication on fresh shell fragments from turkey hatching eggs under conditions present in a hatcher incubator was investigated. A 10⁵-fold amplification was observed both by colony count and total cell count gaining 4 × 10⁷ cfu/cells per gram eggshell within 30 hr of incubation. Furthermore, the bacterial community present on eggshells was analyzed by generation of 16S rRNA gene clone libraries and identification of eight isolates. RFLP analysis revealed no shift in community composition during incubation and Enterococcus faecalis and Enterococcus gallinarum were found as the predominant species on turkey eggshells, both have been classified as risk group 2 microorganisms (German TRBA 466). Since Enterococcus spp. were found as predominant species on turkey eggshells, contribution of this genus to bioaerosol formation was demonstrated. During different work activities with poult and eggshell handling concentrations of airborne enterococci up to 1.3 × 10⁴ cfu m^?3 were detected. In contrast, no enterococci were identified at a day without poult or eggshell processing. In conclusion, turkey hatching eggs carry a viable specific microflora from breeder flocks to hatcheries. After hatching of turkey poults, hatcher incubators and eggshell fragments provide appropriate conditions for excessive bacterial growth. Thus, high bacterial loads on eggshell fragments are a source of potential harmful bioaersols caused by air flows, poult activity, and handling of equipment.     

Improvement of the air quality in student health centers with chlorine dioxide

This study aims to monitor bioaerosol levels of a local campus of a student health center in Taiwan and then to perform disinfection by applying chlorine dioxide. First, air samples were taken and evaluated in the six areas of the center. The average background bioaerosol levels were 714 ± 1706 CFU/m³ for bacterium and 802 ± 633 CFU/m³ for fungi. Then, chlorine dioxide was applied through three different procedures: single, multiple and regular disinfections. The results indicated that both multiple and regular disinfections can achieve efficiency levels higher than 59.0%. The regression analysis on bioaerosol levels showed that the number of people present correlating to the number of persons entering the room per door-opening, had a correlation of p < 0.05. Utilizing this analysis result, an empirical model was developed to predict indoor bioaerosol concentrations. It can be inferred that for indoor human activity of health centers, regular disinfection is a very effective process.     

Temporal and Spatial Patterns of Ambient Endotoxin Concentrations in Fresno,California

Background

Endotoxins are found in indoor dust generated by human activity and pets, in soil, and adsorbed onto the surfaces of ambient combustion particles. Endotoxin concentrations have been associated with respiratory symptoms and the risk of atopy and asthma in children.

Objective

We characterized the temporal and spatial variability of ambient endotoxin in Fresno/Clovis, California, located in California’s Central Valley, to identify correlates and potential predictors of ambient endotoxin concentrations in a cohort of children with asthma [Fresno Asthmatic Children’s Environment Study (FACES)].

Methods

Between May 2001 and October 2004, daily ambient endotoxin and air pollutants were collected at the central ambient monitoring site of the California Air Resources Board in Fresno and, for shorter time periods, at 10 schools and indoors and outdoors at 84 residences in the community. Analyses were restricted to May–October, the dry months during which endotoxin concentrations are highest.

Results

Daily endotoxin concentration patterns were determined mainly by meteorologic factors, particularly the degree of air stagnation. Overall concentrations were lowest in areas distant from agricultural activities. Highest concentrations were found in areas immediately downwind from agricultural/pasture land. Among three other measured air pollutants [fine particulate matter, elemental carbon (a marker of traffic in Fresno), and coarse particulate matter (PM_c)], PM_c was the only pollutant correlated with endotoxin. Endotoxin, however, was the most spatially variable.

Conclusions

Our data support the need to evaluate the spatial/temporal variability of endotoxin concentrations, rather than relying on a few measurements made at one location, in studies of exposure and and respiratory health effects, particularly in children with asthma and other chronic respiratory diseases.     

Health complaints and immunological markers of exposure to bioaerosols among biowaste collectors and compost workers

OBJECTIVES—In a cross sectional study, work related health complaints and diseases of 58 compost workers and 53 biowaste collectors were investigated and compared with 40 control subjects. Levels of specific IgG antibodies to moulds and bacteria were measured as immunological markers of exposure to bioaerosols.
METHODS—With a standardised protocol, the participants of the study were interviewed for work related symptoms, conditions of exposure to bioaerosols at their workplaces, exposure to bioaerosols from other sources, atopic diseases, and smoking habits. They were clinically examined by physicians specialised in occupational medicine. Also, concentrations of specific IgG antibodies against antigens of moulds and actinomycetes occurring regularly at these workplaces were measured and compared with the health complaints of the workers.
RESULTS—Compost workers had significantly more symptoms and diseases of the airways (p=0.003) and the skin (p=0.02) than the control subjects. Health complaints of biowaste collectors did not differ significantly from those of the control group. Subjects with atopic diseases were underrepresented in the compost workers (p=0.003). Significantly increased antibody concentrations against fungi and actinomycetes were measured in workers at composting plants. The concentrations in biowaste collectors did not differ significantly from those in the control subjects. A significant association between the diseases and increased antibody concentrations were found in the compost workers.
CONCLUSION—The high exposure to bioaerosols of compost workers is significantly associated with a higher frequency of health complaints and diseases as well as higher concentrations of specific antibodies against moulds and actinomycetes. A healthy worker effect is indicated by the underrepresentation of atopic diseases among the compost workers compared with biowaste collectors and the control group.


Keywords: exposure to bioaerosols; organic dust; IgG antibodies; moulds; actinomycetes