Bio-aerosols are airborne particles that are living (bacteria, viruses and fungi) or originate from living organisms. Their presence in air is the result of dispersal from a site of colonization or growth. The health effects of bio-aerosols including infectious diseases, acute toxic effects, allergies and cancer coupled with the threat of bioterrorism and SARS have led to increased awareness on the importance of bio-aerosols. The evaluation of bio-aerosols includes use of variety of methods for sampling depending on the concentration of microorganisms expected. There have been problems in developing standard sampling methods, in proving a causal relationship and in establishing threshold limit values for exposures due to the complexity of composition of bio-aerosols, variations in human response to their exposure and difÞ culties in recovering microorganisms. Currently bio-aerosol monitoring in hospitals is carried out for epidemiological investigation of nosocomial infectious diseases, research into airborne microorganism spread and control, monitoring biohazardous procedures and use as a quality control measure. In India there is little awareness regarding the quality of indoor air, mould contamination in indoor environments, potential source for transmission of nosocomial infections in health care facilities. There is an urgent need to undertake study of indoor air, to generate baseline data and explore the link to nosocomial infections. This article is a review on composition, sources, modes of transmission, health effects and sampling methods used for evaluation of bio-aerosols, and also suggests control measures to reduce the loads of bio-aerosols.

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. 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.

Abstract. In this large-scale longitudinal study conducted in rural Southern India, we compared a presence/absence hydrogen sulfide (H 2 S) test with quantitative assays for total coliforms and Escherichia coli as measures of water quality, health risk, and water supply vulnerability to microbial contamination. None of the three indicators showed a significant association with child diarrhea. The presence of H 2 S in a water sample was associated with higher levels of total coliform species that may have included E. coli but that were not restricted to E. coli. In addition, we observed a strong relationship between the percent positive H 2 S test results and total coliform levels among water source samples (R 2 = 0.87). The consistent relationships between H 2 S and total coliform levels indicate that presence/absence of H 2 S tests provide a cost-effective option for assessing both the vulnerability of water supplies to microbial contamination and the results of water quality management and risk mitigation efforts.

This study was conducted to determine whether mobile phones of healthcare workers (HCWs) and T corporate users harbour micro-organisms. Swabs collected from mobile phones were inoculated in solid and liquid media, and incubated aerobically. Growth was identified as per standard microbiological procedures. Antibiotic susceptibility was determined for Staphylococcus aureus. A questionnaire was used for data collection on awareness of mobile phone use. Of 51 HCWs and 36 corporate mobile phones sampled, only 5 (6%) showed no growth. Pathogens isolated from HCW samples included S. aureus [meticillin-sensitive S. aureus (4), meticillin-resistant S. aureus (2)], Escherichia coli (1), Klebsiella pneumoniae (1) and Pseudomonas aeruginosa (1). Coagulase-negative Staphylococci (43) were also isolated. Among corporate isolates, 29% were pathogenic. Polymicrobial growth was detected in 71% of HCW and 78% of corporate mobile phones. Only 12% of HCWs used disinfectants to wipe their mobile phones. Mobile phones serve as a ready surface for colonisation of nosocomial agents indicating the importance of hand hygiene to prevent cross-transmission.

A 3-month pilot study (February—April 2006) was conducted to determine the quality of indoor air in hospitals in the Tamil Nadu region of India and to characterize the predominant aerobic bacteria and fungi present. The main objectives were (1) to sample the indoor air of three different hospitals in Chennai for bioaerosols to generate baseline data using the Petri plate gravitational settling (passive) method of sampling; and (2) to isolate and identify potentially pathogenic organisms prevalent in the hospital environment. Indoor air samples were collected from various wards at the different hospitals and processed for the identification of various predominant bacteria and fungi. The overall counts of Gram-positive organisms were found to be higher than Gram-negative organisms. Of these isolates, Staphylococci and Micrococci were the predominant Gram-positive bacteria, while Klebsiella sp. and Pseudomonas sp. were the predominant potentially pathogenic Gram-negative bacteria isolated. Among yeasts and molds, Aspergillus niger and A. flavus were commonly isolated.