<i>Legionella pneumophila</i>in aerosols from shower baths

Dennis, P. J.; Wright, Amanda; Rutter, D.A; Death, J. E.; Jones, B.P.C.

doi:10.1017/s0022172400064901

Cited by 48 publications

(31 citation statements)

References 25 publications

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“…Ninety percent of L. pneumophila recovered were in aerosols between 1 and 5 μm in diameter, sizes capable of alveolar deposition. 154 Similar to other studies, when Dennis et al 155 examined L. pneumophila aerosol generation by plumbing in bathrooms, they found very low concentrations (0.27-0.44 CFU m -3 ) of bacteria in the air during the first 15 minutes of showering and no airborne Legionella during 15 and 30 minutes of showering, even though concentrations of L. pneumophila in the water were approximately 10 3 CFU L -3 . At a breathing rate of 12 L min -1 , over 4 hours of showering would be required to inhale just one “viable” Legionella cell (although the researchers likely meant to use the term “culturable” since viable but non-culturable (VBNC) cells were not distinguished in their study).…”

Section: Introductionsupporting

confidence: 79%

Ten questions concerning the aerosolization and transmission of Legionella in the built environment

Prussin

Schwake

Marr

2017

Building and Environment

101

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Legionella is a genus of pathogenic Gram-negative bacteria responsible for a serious disease known as legionellosis, which is transmitted via inhalation of this pathogen in aerosol form. There are two forms of legionellosis: Legionnaires' disease, which causes pneumonia-like symptoms, and Pontiac fever, which causes influenza-like symptoms. Legionella can be aerosolized from various water sources in the built environment including showers, faucets, hot tubs/swimming pools, cooling towers, and fountains. Incidence of the disease is higher in the summertime, possibly because of increased use of cooling towers for air conditioning systems and differences in water chemistry when outdoor temperatures are higher. Although there have been decades of research related to Legionella transmission, many knowledge gaps remain. While conventional wisdom suggests that showering is an important source of exposure in buildings, existing measurements do not provide strong support for this idea. There has been limited research on the potential for Legionella transmission through heating, ventilation, and air conditioning (HVAC) systems. Epidemiological data suggest a large proportion of legionellosis cases go unreported, as most people who are infected do not seek medical attention. Additionally, controlled laboratory studies examining water-to-air transfer and source tracking are still needed. Herein, we discuss ten questions that spotlight current knowledge about Legionella transmission in the built environment, engineering controls that might prevent future disease outbreaks, and future research that is needed to advance understanding of transmission and control of legionellosis.

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Section: Introductionsupporting

confidence: 79%

Ten questions concerning the aerosolization and transmission of Legionella in the built environment

Prussin

Schwake

Marr

2017

Building and Environment

101

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“…Bolin (22) Near aerated sink faucets in a hospital 2 to 9 CFU/m 3 > 2 × 10 5 CFU/L Not associated with LD cases. Based on 6 of 19 positive air samples Dennis (21) Near shower heads 0.33 CFU/m 3 10 3 CFU/L Not associated with LD cases Breiman (96) In shower aerosol 190 CFU/m 3…”

Section: Data Source Location Air Concentration Water Concentration Cmentioning

confidence: 99%

Quantitative Microbial Risk Assessment Model for Legionnaires' Disease: Assessment of Human Exposures for Selected Spa Outbreaks

Armstrong

Haas

2007

Journal of Occupational and Environmental Hygiene

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Evaluation of a quantitative microbial risk assessment (QMRA) model for Legionnaires' disease (LD) required Legionella exposure estimates for several well-documented LD outbreaks. Reports for a whirlpool spa and two natural spring spa outbreaks provided data for the exposure assessment, as well as rates of infection and mortality. Exposure estimates for the whirlpool spa outbreak employed aerosol generation, water composition, exposure duration data, and building ventilation parameters with a two-zone model. Estimates for the natural hot springs outbreaks used bacterial water to air partitioning coefficients and exposure duration information. The air concentration and dose calculations used input parameter distributions with Monte Carlo simulations to estimate exposures as probability distributions. The assessment considered two sets of assumptions about the transfer of Legionella from the water phase to the aerosol emitted from the whirlpool spa. The estimated air concentration near the whirlpool spa was 5 to 18 colony forming units per cubic meter (CFU/m(3)) and 50 to 180 CFU/m(3) for each of the alternate assumptions. The estimated 95th percentile ranges of Legionella dose for workers within 15 m of the whirlpool spa were 0.13-3.4 CFU and 1.3-34.5 CFU, respectively. The modeling for hot springs Spas 1 and 2 resulted in estimated arithmetic mean air concentrations of 360 and 17 CFU/m(3), respectively, and 95 percentile ranges for Legionella dose of 28 to 67 CFU and 1.1 to 3.7 CFU, respectively. The Legionella air concentration estimates fall in the range of limited reports on air concentrations of Legionella (0.33 to 190 CFU/m(3)) near showers, aerated faucets, and baths during filling with Legionella-contaminated water. These measurements may provide some indication that the estimates are of a reasonable magnitude, but they do not clarify the exposure estimates accuracy, since they were not obtained during LD outbreaks. Further research to improve the data used for the Legionella exposure assessment would strengthen the results. Several of the primary additional data needs include improved data for bacterial water to air partitioning coefficients, better accounting of time-activity-distance patterns and exposure potential in outbreak reports, and data for Legionella-containing aerosol viability decay instead of loss of capability for growth in culture.

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“…L. pneumophila has been isolated from aerosols created by water faucets (24), by humidifiers, and by the squeezing of manual ventilation bags (277). Some investigators have been able to demonstrate legionellae in aerosols produced by showers (24,55), but others have been unsuccessful (277). In one study, L. pneumophila was isolated during two successive 15-min periods (24), whereas Dennis and colleagues were able to recover legionellae only during the first sampling period (55).…”

Section: Route Of Infectionmentioning

confidence: 99%

“…Some investigators have been able to demonstrate legionellae in aerosols produced by showers (24,55), but others have been unsuccessful (277). In one study, L. pneumophila was isolated during two successive 15-min periods (24), whereas Dennis and colleagues were able to recover legionellae only during the first sampling period (55). Analysis of aerosols with cascade impingers has shown that the bacteria are contained in droplets that are of respirable size (55).…”

Section: Route Of Infectionmentioning

confidence: 99%

“…In one study, L. pneumophila was isolated during two successive 15-min periods (24), whereas Dennis and colleagues were able to recover legionellae only during the first sampling period (55). Analysis of aerosols with cascade impingers has shown that the bacteria are contained in droplets that are of respirable size (55). In all of these studies very small numbers of bacteria were isolated, and it is not clear whether the inocula would be infectious for humans.…”

Section: Route Of Infectionmentioning

confidence: 99%

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Legionnaires disease: historical perspective

1988

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In the summer of 1976, a mysterious epidemic of fatal respiratory disease in Philadelphia launched an intensive investigation that resulted in the definition of a new family of pathogenic bacteria, the Legionellaceae. In retrospect, members of the family had been isolated from clinical specimens as early as 1943. Unsolved epidemics of acute respiratory disease dating to the 1950s were subsequently attributed to the newly described pathogens. In the intervening years, the Legionellaceae have been firmly established as important causes of sporadic and epidemic respiratory disease. The sources of the infecting bacteria are environmental, and geographic variation in the frequency of infection has been documented. Airborne dissemination of bacteria from cooling towers and evaporative condensers has been responsible for some epidemics, but potable water systems are perhaps more important sources. The mode of transmission from drinking water is unclear. The Legionellaceae are gram-negative, facultative, intracellular pathogens. The resident alveolar macrophage, usually an effective antibacterial defense, is the primary site of growth. Cell-mediated immunity appears to be the most important immunological defense; the role of humoral immunity is less clear. Erythromycin remains the antibiotic of choice for therapy of infected patients, but identification and eradication of environmental sources are also essential for the control of infection.

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Legionella pneumophilain aerosols from shower baths

Cited by 48 publications

References 25 publications

Ten questions concerning the aerosolization and transmission of Legionella in the built environment

Ten questions concerning the aerosolization and transmission of Legionella in the built environment

Quantitative Microbial Risk Assessment Model for Legionnaires' Disease: Assessment of Human Exposures for Selected Spa Outbreaks

Legionnaires disease: historical perspective

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