The Stafford outbreak of Legionnaires' disease

Vascular Access for Home Hemodialysis: A Perspective on Tunneled Central Venous Catheters at Home

Expansion of home hemodialysis (HHD) provides an opportunity to improve clinical outcomes, reduce cost of care, and address the staffing challenges currently faced in caring for patients with kidney failure on replacement therapy. To increase HHD expansion, current practices and barriers to home dialysis must be examined and addressed. One such barrier is vascular access for HHD; although tunneled hemodialysis central venous catheters (CVCs) have been used for decades, physicians still hesitate to send patients home without a mature, functional arteriovenous access. An expert panel of clinicians was convened by Outset Medical, a manufacturer of hemodialysis systems, to review the literature and generate consensus recommendations regarding the use of CVCs for HHD. Consistent with the most recent Kidney Disease Outcomes vascular access guidelines, the end-stage kidney disease life plan should be created via shared decision making for modality choices, with the corresponding dialysis access individualized for the patient, and for whom a CVC may represent the most appropriate vascular access to provide HHD.

The mysterious illness that drove them to their knees - Ah, that Legionnaires' disease - A historical reflection of the work in Legionnaires' disease in New Zealand (1978 to mid-1990s) and the 'One Health' paradigm

And so, formed the basis for the song Legionnaires' disease (LD) composed by the legendry musician Bob Dylan shortly after this mysterious illness dramatically entered the clinical and epidemiological scene in July 1976 at an American hotel. Now more than forty years have passed since Legionella pneumophila, the causative agent of LD, was formally identified in 1977. Once the publicity associated with the outbreak subsided, there was the challenge to science and health professionals of what was an extremely complex and intriguing health concern. In the United States, the outbreak investigation that eventually solved the mystery had taken an array of surprising twists and turns. Globally, it revealed the strengths and weakness of countries' health systems in response to the outbreak from an unknown agent. Extensive international coverage of the outbreak also marked a turning point in journalism's efforts to hold officials accountable for their response to epidemics that had the potential to threaten the lives of hundreds of people. In 1979, New Zealand became an active participant in the international efforts towards increasing the understanding of infection caused by Legionella species and set up a centralized laboratory diagnostic service. By 1980 LD had become a notifiable disease making New Zealand one of the first countries globally to do so. This historical narrative in the decade or so from its recognition, provides a unique insight into how the One Health paradigm was instrumental in New Zealand's early response to LD in tandem with control strategies. The findings show that from 1979 the distribution of the Legionella species in New Zealand did not follow patterns observed in studies carried out globally.

Identification, classification and shortlisting of performance indicators for hospital facilities management

Purpose

This paper aims to report on a study that aims to establish a list of systematically classified key performance indicators (KPIs) that are useful for hospital facilities management (FM).

Design/methodology/approach

A review of literature was conducted to identify indicators that are applicable to hospital FM. Each indicator was classified using a phase–hierarchy (P-H) model, which is a two-dimensional matrix comprising three phases (input, process and output) of facilities services delivery and three hierarchical FM levels (operational, tactical and strategic). The classified indicators were further shortlisted via a focus group study.

Findings

From the literature review, 61 indicators were identified as applicable to hospital FM. Most of the indicators, according to the P-H model, are for evaluating the FM input or output phase, at the strategic or tactical level. Further refinement and shortlisting of the indicators by the focus group experts resulted in 18 KPIs, which fall into 4 aspects: “physical”, “safety”, “environmental” and “financial”.

Research limitations/implications

The study illustrates that the P-H model is useful for classifying the performance indicators systematically along the two fundamental FM dimensions – phase and hierarchy. Further research may use this model to classify performance indicators in other contexts.

Practical implications

The method of this study can be adapted for use in identifying, classifying and shortlisting FM performance indicators for other types of buildings. The shortlisted KPIs can be used for assessing the FM performance of hospitals.

Originality/value

To the best of the authors’ knowledge, this study is the first of its kind that used the P-H model to classify hospital FM performance indicators.

Legionella pneumophila and Protozoan Hosts: Implications for the Control of Hospital and Potable Water Systems

Legionella pneumophila is an opportunistic waterborne pathogen of public health concern. It is the causative agent of Legionnaires’ disease (LD) and Pontiac fever and is ubiquitous in manufactured water systems, where protozoan hosts and complex microbial communities provide protection from disinfection procedures. This review collates the literature describing interactions between L. pneumophila and protozoan hosts in hospital and municipal potable water distribution systems. The effectiveness of currently available water disinfection protocols to control L. pneumophila and its protozoan hosts is explored. The studies identified in this systematic literature review demonstrated the failure of common disinfection procedures to achieve long term elimination of L. pneumophila and protozoan hosts from potable water. It has been demonstrated that protozoan hosts facilitate the intracellular replication and packaging of viable L. pneumophila in infectious vesicles; whereas, cyst-forming protozoans provide protection from prolonged environmental stress. Disinfection procedures and protozoan hosts also facilitate biogenesis of viable but non-culturable (VBNC) L. pneumophila which have been shown to be highly resistant to many water disinfection protocols. In conclusion, a better understanding of L. pneumophila-protozoan interactions and the structure of complex microbial biofilms is required for the improved management of L. pneumophila and the prevention of LD.

Identifying aerosolized cyanobacteria in the human respiratory tract: A proposed mechanism for cyanotoxin-associated diseases

Cyanobacteria produce harmful toxins that have been associated with several acute conditions and chronic human diseases, like gastroenteritis, non-alcoholic liver disease, and amyotrophic lateral sclerosis. Aerosol from waterbodies appears to be a likely mechanism for exposure. We conducted a study of human biospecimens focused on the cyanobacterial aerosilization process by evaluating the extent to which cyanobacteria can invade the human respiratory tract. Our study suggests that humans routinely inhale aerosolized cyanobacteria, which can be harbored in the nostrils and the lungs. Using PCR, cyanobacteria were found at high frequencies in the upper respiratory tract (92.20%) and central airway (79.31%) of our study subjects. Nasal swabs were not predictive of bronchoalveolar lavage (BAL) when detecting inhaled cyanobacteria. Interestingly, we found no evidence that time of year was a significant factor for cyanobacteria positivity (BAL cytology p = 1.0 and PCR p = 1.0); (nasal swab cytology p = 0.051 and PCR p = 0.65). Additionally, we found that proximity to a waterbody was not a significant factor for cyanobacteria positivity in BAL and nasal swabs collected during cyanobacteria bloom season [May-October] (p = 0.46 and p = 0.38). These data suggest that cyanobacteria exposure may be a prevalent and chronic phenomenon not necessarily restricted to waterbodies alone. Sources of indoor exposure warrant future investigation. Given the widespread prevalence of cyanobacterial exposure in the airway, investigation of the aerosol spread of cyanotoxins, more specifically, is warranted. Our findings are consistent with the hypothesis that aerosol is a significant route for cyanobacteria exposure, and thus a likely route of transmission for cyanotoxin-associated human diseases.

Spatial structuring of a Legionella pneumophila population within the water system of a large occupational building

The diversity of Legionella pneumophila populations within single water systems is not well understood, particularly in those unassociated with cases of Legionnaires’ disease. Here, we performed genomic analysis of 235 L. pneumophila isolates obtained from 28 water samples in 13 locations within a large occupational building. Despite regular treatment, the water system of this building is thought to have been colonized by L. pneumophila for at least 30 years without evidence of association with Legionnaires’ disease cases. All isolates belonged to one of three sequence types (STs), ST27 (n=81), ST68 (n=122) and ST87 (n=32), all three of which have been recovered from Legionnaires’ disease patients previously. Pairwise single nucleotide polymorphism differences amongst isolates of the same ST were low, ranging from 0 to 19 in ST27, from 0 to 30 in ST68 and from 0 to 7 in ST87, and no homologous recombination was observed in any lineage. However, there was evidence of horizontal transfer of a plasmid, which was found in all ST87 isolates and only one ST68 isolate. A single ST was found in 10/13 sampled locations, and isolates of each ST were also more similar to those from the same location compared with those from different locations, demonstrating spatial structuring of the population within the water system. These findings provide the first insights into the diversity and genomic evolution of a L. pneumophila population within a complex water system not associated with disease.

Legionellosis Outbreak Associated With a Hotel Fountain

Background. In August 2012, the Chicago Department of Public Health (CDPH) was notified of acute respiratory illness, including 1 fatality, among a group of meeting attendees who stayed at a Chicago hotel during July 30–August 3, 2012. Suspecting Legionnaires' disease (LD), CDPH advised the hotel to close their swimming pool, spa, and decorative lobby fountain and began an investigation.

Methods. Case finding included notification of individuals potentially exposed during July 16–August 15, 2012. Individuals were interviewed using a standardized questionnaire. An environmental assessment was performed.

Results. One hundred fourteen cases were identified: 11 confirmed LD, 29 suspect LD, and 74 Pontiac fever cases. Illness onsets occurred July 21–August 22, 2012. Median age was 48 years (range, 22–82 years), 64% were male, 59% sought medical care (15 hospitalizations), and 3 died. Relative risks for hotel exposures revealed that persons who spent time near the decorative fountain or bar, both located in the lobby were respectively 2.13 (95%, 1.64–2.77) and 1.25 (95% CI, 1.09–1.44) times more likely to become ill than those who did not. Legionella pneumophila serogroup 1 was isolated from samples collected from the fountain, spa, and women's locker room fixtures. Legionella pneumophila serogroup 1 environmental isolates and a clinical isolate had matching sequence-based types. Hotel maintenance records lacked a record of regular cleaning and disinfection of the fountain.

Conclusions. Environmental testing identified Legionella in the hotel's potable water system. Epidemiologic and laboratory data indicated the decorative fountain as the source. Poor fountain maintenance likely created favorable conditions for Legionella overgrowth.

Confirmed and Potential Sources of Legionella Reviewed

Legionella bacteria are ubiquitous in natural matrices and man-made systems. However, it is not always clear if these reservoirs can act as source of infection resulting in cases of Legionnaires' disease. This review provides an overview of reservoirs of Legionella reported in the literature, other than drinking water distribution systems. Levels of evidence were developed to discriminate between potential and confirmed sources of Legionella. A total of 17 systems and matrices could be classified as confirmed sources of Legionella. Many other man-made systems or natural matrices were not classified as a confirmed source, since either no patients were linked to these reservoirs or the supporting evidence was weak. However, these systems or matrices could play an important role in the transmission of infectious Legionella bacteria; they might not yet be considered in source investigations, resulting in an underestimation of their importance. To optimize source investigations it is important to have knowledge about all the (potential) sources of Legionella. Further research is needed to unravel what the contribution is of each confirmed source, and possibly also potential sources, to the LD disease burden.

Barrow-in-Furness: a large community legionellosis outbreak in the UK

A community outbreak of legionellosis occurred in Barrow-in-Furness, Cumbria, during July and August 2002. A descriptive study and active case-finding were instigated and all known wet cooling systems and other potential sources were investigated. Genotypic and phenotypic analysis, and amplified fragment length polymorphism of clinical human and environmental isolates confirmed the air-conditioning unit of a council-owned arts and leisure centre to be the source of infection. Subsequent sequence-based typing confirmed this link. One hundred and seventy-nine cases, including seven deaths [case fatality rate (CFR) 3·9%] were attributed to the outbreak. Timely recognition and management of the incident very likely led to the low CFR compared to other outbreaks. The outbreak highlights the responsibility associated with managing an aerosol-producing system, with the potential to expose and infect a large proportion of the local population and the consequent legal ramifications and human cost.

Large outbreak of Legionnaires' disease and Pontiac fever at a military base

We investigated a mixed outbreak of Legionnaires' disease (LD) and Pontiac fever (PF) at a military base to identify the outbreak's environmental source as well as known legionellosis risk factors. Base workers with possible legionellosis were interviewed and, if consenting, underwent testing for legionellosis. A retrospective cohort study collected information on occupants of the buildings closest to the outbreak source. We identified 29 confirmed and probable LD and 38 PF cases. All cases were exposed to airborne pathogens from a cooling tower. Occupants of the building closest to the cooling tower were 6·9 [95% confidence interval (CI) 2·2–22·0] and 5·5 (95% CI 2·1–14·5) times more likely to develop LD and PF, respectively, than occupants of the next closest building. Thorough preventive measures and aggressive responses to outbreaks, including searching for PF cases in mixed legionellosis outbreaks, are essential for legionellosis control.

Investigation of outbreaks: epidemiology

Outbreaks of Legionnaires' disease create high levels of public anxiety and media interest and inevitably consume a great deal of public health resources. Investigations should begin as early as possible in order to rapidly identify suspected sources of infection, control the outbreak and prevent further cases occurring. The investigations should be coordinated by an outbreak control team who work collaboratively within local/national/international public health guidelines and with clear terms of reference. The actions carried out by epidemiologists when investigating community-, hospital-, or travel-associated outbreaks are comprehensively outlined in this chapter. The microbiological and environmental actions that complement this work are discussed in the accompanying chapters.

Assessing maintenance of evaporative cooling systems in legionellosis outbreaks

This study was designed to conduct systematic reviews of existing evaporative cooling system maintenance guidelines and of published Legionnaires' disease outbreaks to determine what, if any, maintenance practices were in place at the time of the disease outbreaks and then to contrast the reported practices with the published guidelines for evaporative cooling systems. For the first review, similarities in the reported recommendations were assessed; in the second review, any reported information about the state of the evaporative cooling system during the outbreak investigation was summarized. The systematic reviews yielded 38 current guidelines for evaporative cooling systems and 38 published outbreak investigations. The guidelines varied regarding the recommended type and dose of biocides, frequency of general inspections and total system maintenance, the preferred disinfection and cleaning procedures when testing a system for microbiological contamination, the type and frequency of testing procedures, and interpretation of test results. Overall, the maintenance guidelines did not contain sufficiently detailed procedures to prevent the problems that were observed in the outbreak investigations. These maintenance procedures included lack or improper use of a biocide; infrequent testing for microbiological contamination; improper use or maintenance of drift eliminators; and lack of a total system cleaning within 6 months of the outbreak for cooling systems that were either under continuous use, recently started up, or frequently switched on and off. This study suggests that more specific and standardized maintenance guidelines for the control of Legionella bacteria are needed and that these guidelines must be properly implemented to help reduce further Legionnaires' disease outbreaks associated with evaporative cooling systems.

Isolation and characterization of Acanthamoeba spp. from air-conditioners in Kuala Lumpur, Malaysia

During a study on the quality of the indoor environment, Acanthamoeba spp. were detected in 20 out of 87 dust samples collected from air-conditioners installed in a four-story campus building located in Kuala Lumpur, Malaysia. Twenty-one cloned Acanthamoeba isolates designated as IMU1 to IMU21 were established from the positive primary cultures. Five species were identified from the 16 isolates according to the morphological criteria of Pussard and Pons; i.e. A. castellanii, A. culbertsoni, A. griffini, A. hatchetti and A. polyphaga. Species identities for the remaining five isolates (IMU4, IMU5, IMU15, IMU20 and IMU21), however, could not be determined morphologically. At genotypic characterization, these isolates were placed into T3 (IMU14); T5 (IMU16 and IMU17) and T4 (all the remaining isolates). To predict the potential pathogenicity of these Acanthamoeba isolates, thermo- and osmotolerance tests were employed; many isolates were predicted as potential human pathogens based on the outcome of these tests. This is the first time potentially pathogenic Acanthamoeba have been isolated from air-conditioners in Malaysia.

Controlling legionella risk in a newly commissioned hospital building

We describe the risk assessment and interventions used for Legionella spp. in potable water in a new building commissioned in 2007. Water systems were designed to be compliant with Health Technical Memoranda 04-01 and the approved Code of Practice and Guidance for the control of legionella bacteria in water systems, known as L8. Monitoring of cold-water outlets showed temperature greater than 20°C. Water samples were cultured for legionella. Control measures used increased flushing and a copper—silver ionization system. Nocturnal heat gain was noticed in the cold-water system. Legionella pneumophila serogroup 1 was cultured from one representative outlet. The copper— silver ionization system reduced legionella colony counts. Water consumption was 71% of the original design estimate. No clinical cases due to Legionella spp. were detected. Reduced water consumption may lead to heat gain even in well-insulated systems, thus breaching control guidance. Additional control methods will then be required.

Viability PCR, a culture-independent method for rapid and selective quantification of viable Legionella pneumophila cells in environmental water samples

PCR-based methods have been developed to rapidly screen for Legionella pneumophila in water as an alternative to time-consuming culture techniques. However, these methods fail to discriminate between live and dead bacteria. Here, we report a viability assay (viability PCR [v-PCR]) for L. pneumophila that combines ethidium monoazide bromide with quantitative real-time PCR (qPCR). The ability of v-PCR to differentiate viable from nonviable L. pneumophila cells was confirmed with permeabilizing agents, toluene, or isopropanol. v-PCR suppressed more than 99.9% of the L. pneumophila PCR signal in nonviable cultures and was able to discriminate viable cells in mixed samples. A wide range of physiological states, from culturable to dead cells, was observed with 64 domestic hot-water samples after simultaneous quantification of L. pneumophila cells by v-PCR, conventional qPCR, and culture methods. v-PCR counts were equal to or higher than those obtained by culture and lower than or equal to conventional qPCR counts. v-PCR was used to successfully monitor in vitro the disinfection efficacy of heating to 70 degrees C and glutaraldehyde and chlorine curative treatments. The v-PCR method appears to be a promising and rapid technique for enumerating L. pneumophila bacteria in water and, in comparison with conventional qPCR techniques used to monitor Legionella, has the advantage of selectively amplifying only viable cells.

Seroepidemiological study after a long-distance industrial outbreak of legionnaires' disease

Following a long-distance outbreak of Legionnaires' disease from an industrial air scrubber in Norway in 2005, a seroepidemiological study measuring levels of immunoglobulin G (IgG) and IgM antibodies to Legionella pneumophila was performed with a polyvalent enzyme-linked immunosorbent assay. One year after the outbreak, IgG levels in employees (n = 213) at the industrial plant harboring the scrubber and in blood donors (n = 398) from the outbreak county were low but significantly higher (P < or = 0.002) than those in blood donors (n = 406) from a nonexposed county. No differences in IgM levels among the three groups were found after adjustment for gender and age. Home addresses of the seroresponders in the exposed county clustered to the city of the outbreak, in contrast to the scattering of addresses of the seroresponding donors in the nonexposed county. Factory employees who operated at an open biological treatment plant had significantly higher IgG and IgM levels (P < or = 0.034) than those working >200 m away. Most of the healthy seroresponders among the factory employees worked near this exposure source. Immunoblotting showed that IgG and IgM antibodies in 82.1% of all seroresponders were directed to the lipopolysaccharide of the L. pneumophila serogroup 1 outbreak strain. In conclusion, 1 year after the long-distance industrial outbreak a small increase in IgG levels of the exposed population was observed. The open biological treatment plant within the industrial premises, however, constituted a short-distance exposure source of L. pneumophila for factory employees working nearby.

Lessons learned from handling a large rural outbreak of Legionnaires’ disease: Hereford, UK 2003

The outbreak of Legionnaires' disease that occurred in Hereford, West Midlands UK in 2003 was the single largest outbreak of Legionnaires' in Hereford and one of the first to challenge the newly formed Health Protection Agency. This was, de facto a 'public health incident' requiring not only the investigation and management of a community outbreak of infectious disease, but also one that had to take into account other issues including: uncertainty regarding roles and responsibilities, political considerations and communication needs including sustained media attention. The incident also demonstrated the 'added value' of an integrated health protection response. The practical lessons learned from outbreaks are rarely described, particularly operational aspects. This paper summarises the outbreak, outlines specific elements of the response and identifies some of the key learning points for the new Agency and its partners. A number of these lessons have a generic applicability to the handling of public health incidents.

Investigation of an outbreak of Legionnaires' disease: Hereford, UK 2003

This report describes the investigation and control of a community outbreak of Legionnaires' disease in Hereford, UK, in November 2003. Outbreak investigation consisted of epidemiological survey, identification and environmental investigation of potential sources, microbiological analysis of clinical and environmental samples and mapping the location of potential sources and the movement and residence of cases. Each identified source was allocated a 'composite score' based on different zones of exposure and wind direction. Altogether, 28 cases were identified, with an overall case fatality rate of 7%. All cases had epidemiological links to Hereford city centre. The 'composite score' identified a cluster of cooling towers as being the most likely source of the outbreak. Environmental samples from one of the cooling towers in the cluster and clinical samples from two patients were positive for Legionella pneumophilia serogroup 1 and were indistinguishable by molecular sub-typing. In this outbreak, the use of microbiological, environmental and epidemiological techniques facilitated the rapid identification of a cooling tower as the source of this outbreak. This study illustrates the continuing importance of cooling towers as a source of Legionnaires' disease and the utility of obtaining and comparing both clinical and environmental samples.

Public health professionals' perceptions toward provision of health protection in England: a survey of expectations of Primary Care Trusts and Health Protection Units in the delivery of health protection

BACKGROUND

Effective health protection requires systematised responses with clear accountabilities. In England, Primary Care Trusts and the Health Protection Agency both have statutory responsibilities for health protection. A Memorandum of Understanding identifies responsibilities of both parties, but there is a potential lack of clarity about responsibility for specific health protection functions. We aimed to investigate professionals' perceptions of responsibility for different health protection functions, to inform future guidance for, and organisation of, health protection in England.

METHODS

We sent a postal questionnaire to all health protection professionals in England from the following groups: (a) Directors of Public Health in Primary Care Trusts; (b) Directors of Health Protection Units within the Health Protection Agency; (c) Directors of Public Health in Strategic Health Authorities and; (d) Regional Directors of the Health Protection Agency

RESULTS

The response rate exceeded 70%. Variations in perceptions of who should be, and who is, delivering health protection functions were observed within, and between, the professional groups (a)-(d). Concordance in views of which organisation should, and which does deliver was high (> or =90%) for 6 of 18 health protection functions, but much lower (< or =80%) for 6 other functions, including managing the implications of a case of meningitis out of hours, of landfill environmental contamination, vaccination in response to mumps outbreaks, nursing home infection control, monitoring sexually transmitted infections and immunisation training for primary care staff. The proportion of respondents reporting that they felt confident most or all of the time in the safe delivery of a health protection function was strongly correlated with the concordance (r = 0.65, P = 0.0038).

CONCLUSION

Whilst we studied professionals' perceptions, rather than actual responses to incidents, our study suggests that there are important areas of health protection where consistent understanding of responsibility for delivery is lacking. There are opportunities to clarify the responsibility for health protection in England, perhaps learning from the approaches used for those health protection functions where we found consistent perceptions of accountability.

No evidence of Legionella infection in general practice patients presenting with acute respiratory infections in The Netherlands

The role of Legionella spp. in the aetiology of acute respiratory infections (ARIs) is largely unknown. In this case-control study, conducted in a general practitioner setting during 2000 and 2001, nose and throat samples from patients presenting with ARIs (n = 230) and controls (n = 200) were analysed for the presence of Legionella spp. by real-time PCR. Legionella DNA was not detected in any of the cases or controls. Thus, Legionella spp. do not seem to play a role in patients presenting with ARIs, nor were they present in patients who visited their general practitioner for complaints other than ARIs.

Estimation of minimum infection rates with Legionella pneumophila in an exposed population

The distribution of antibody levels to Legionella (L.) pneumophila (serotypes 1-7) was compared between subjects who worked near the source of a large outbreak of Legionnaires' disease (n=668) and a population sample of comparable age (n=480). In a previous analysis of these data, it was estimated that 80% of those working near the source were infected with L. pneumophila. However, the estimation procedure implicitly assumes that the probability of infection does not depend on the antibody level of a person before exposure. This is questionable, as antibodies could protect against infection. We have now estimated the minimum value consistent with the data on the number of infected persons. We observed that a minimum of 40% [95% confidence interval (CI) 32-48] of those working near the source and 13% (95% CI 8-18) of those working further away were infected with L. pneumophila. Implications of these findings for design options in future research are discussed.

Development of a nosocomial outbreak investigation database

A pilot web-based database was created to facilitate epidemiological investigation of nosocomial outbreaks. The database provides highly structured abstracts in a case study format to serve as a guide for investigations. Problems encountered in abstracting over 330 published reports included missing information and classification of study methods. The database offers a new way to review outbreaks, for example, in terms of their impact measured by various combinations of database fields, such as the number of cases, attack rate, pathogens, service/ward and mode of transmission. Feedback from users of the database suggests its usefulness. Creation of a large web-based database seems to be both desirable and feasible.

Epidemiologic Investigation of a Restaurant-Associated Outbreak of Pontiac Fever

This case-control study investigated a cluster of respiratory illness among patrons of a restaurant. Of 173 patrons interviewed, 117 (68%) were ill. Symptoms included myalgias (93%), headache (87%), and fatigue (79%). The mean incubation period was 49 h and the mean duration of illness was 71 h. Patrons aged >15 years were more likely to have been ill than younger patrons (odds ratio [OR], 2.96; P=.002); 58% of persons who were ill sat near a large fountain, compared with 18% of respondents who were not ill (OR, 7.5; P=.005). Legionella anisa was cultured from water samples obtained from the fountain pool. Of 22 individuals who were ill, 11 (50%) had a > or =4-fold increase in the titer of antibody to that strain of L. anisa from acute-phase to convalescent-phase serum samples; 3 others (14%) had persistently elevated titers of > or =512; of a group of 20 individuals who had not been exposed to the restaurant, none had titers of >128. Pontiac fever should be considered as a diagnosis during acute outbreaks of influenza-like illness with a high attack rate and no other identified etiology.

Infection control of lung function equipment: a practical approach

The degree of risk of cross-infection of patients via lung function testing equipment has yet to be quantified. Based on current evidence, elaborate precautions are not justified for the majority of patients attending the laboratory, but attention to appropriate routine cleaning and disinfection protocols is important. Disinfection and sterilization can be achieved by a variety of methods, although chemical methods should be used with caution. Identification of factors increasing the susceptibility or infectivity of particular patients is important in determining appropriate precautions. Where patients are known to be infectious or are immunocompromized, additional precautions such as using a barrier filter may be appropriate. However, because of cost constraints, the routine use of barrier filters is difficult to justify based on current evidence of minimal cross-infection associated with lung function equipment. Until further studies have been conducted to quantify the degree of risk of cross-infection that lung function test equipment poses, the recommendations given in this review provide a practical approach to dealing with this problem.

An evaluation of the efficacy of Aqualox for microbiological control of industrial cooling tower systems

A comprehensive sampling protocol was employed to evaluate the efficacy of Aqualox, a biocide based on electrochemically activated water, against legionellae and heterotrophic bacteria in two industrial cooling tower systems. Both of the towers in the study remained free from evidence of Legionella spp. contamination throughout a five-month evaluation period, despite the previously demonstrated presence of legionellae in one of the test towers, and in two other towers on the same site, at levels well in excess of UK Health and Safety Commission (HSC) Approved Code of Practice and Guidance (ACOP) upper action limits. Levels of heterotrophic bacteria were controlled below 10(4) cfu/mL in both towers throughout most of the trial. Results also provided indirect evidence of significant activity against biofilm bacteria, with biofilm removal beginning almost immediately after commissioning of the Aqualox treatment systems. The results were particularly encouraging as the two towers studied had a long history of poor microbiological control using conventional bromine-based biocide products. Significant differences were observed between laboratory measurements of total viable counts on frequent liquid samples and those obtained from dip slides following HSC recommendations.

Community spread of Legionella pneumophila serogroup 1 in temporal relation to a nosocomial outbreak

To clarify whether a nosocomial outbreak of legionnaires' disease in the Värnamo hospital in Sweden was part of a wider outbreak in the Värnamo community a number of investigations were performed. First, the proportion of cases of legionnaires' disease in a group with nosocomially acquired pneumonia (11%) was compared to the proportion within a group with community-acquired pneumonia (14%) and the difference was found not to be significant (p > 0.05). Second, the proportion of the nursing staff at the Värnamo hospital with an elevated antibody titre (> or = 16) to Legionella pneumophila serogroup (sg) 1 (33%, 84/258) was compared to the proportion in a group of local residents of Värnamo community (26%, 25/96) and found not to be significant; in contrast, comparison with the proportion in a group from the assistant nursing staff at another hospital 60 km away (5%, 4/80) was highly significant (p < 0.001). Furthermore, Legionella species were cultured from samples drawn from the hospital water supply as well from the water supply from municipal buildings. In 1996 a follow-up study was conducted, which showed that < 1% of the assistant nurses and local residents had an elevated titre to L. pneumophila sg 1. These results indicate that there was a temporary spread of L. pneumophila sg 1 in the Värnamo community at the beginning of 1991, both in the local hospital and the surrounding community. This implies that physicians should be aware of community-acquired cases of legionnaires' disease when a nosocomial outbreak is detected.

Waterborne outbreak of tularemia associated with crayfish fishing

In 1997, an outbreak of human tularemia associated with hare-hunting in central Spain affected 585 patients. We describe the identification of Francisella tularensis biovar palaearctica in a second outbreak of ulceroglandular tularemia associated with crayfish (Procambarus clarkii) fishing in a contaminated freshwater stream distant from the hare-associated outbreak. The second outbreak occurred 1 year after the first.

Hospital characteristics associated with colonization of water systems by Legionella and risk of nosocomial legionnaires' disease: a cohort study of 15 hospitals

OBJECTIVE

To investigate an increase in reports of legionnaires' disease by multiple hospitals in San Antonio, Texas, and to study risk factors for nosocomial transmission of legionnaires' disease and determinants for Legionella colonization of hospital hot-water systems.

SETTING

The 16 largest hospitals in the cities of San Antonio, Temple, and Austin, Texas.

DESIGN

Review of laboratory databases to identify patients with legionnaires' disease in the 3 years prior to the investigation and to determine the number of diagnostic tests for Legionella performed; measurement of hot-water temperature and chlorine concentration and culture of potable water for Legionella. Exact univariate calculations, Poisson regression, and linear regression were used to determine factors associated with water-system colonization and transmission of Legionella.

RESULTS

Twelve cases of nosocomial legionnaires' disease were identified; eight of these occurred in 1996. The rise in cases occurred shortly after physicians started requesting Legionella urinary antigen tests. Hospitals that frequently used Legionella urinary antigen tests tended to detect more cases of legionnaires' disease. Legionella was isolated from the water systems of 11 of 12 hospitals in San Antonio; the 12th had just experienced an outbreak of legionnaires' disease and had implemented control measures. Nosocomial legionellosis cases probably occurred in 5 hospitals. The number of nosocomial legionnaires' disease cases in each hospital correlated better with the proportion of water-system sites that tested positive for Legionella (P=.07) than with the concentration of Legionella bacteria in water samples (P=.23). Hospitals in municipalities where the water treatment plant used monochloramine as a residual disinfectant (n=4) and the hospital that had implemented control measures were Legionella-free. The hot-water systems of all other hospitals (n=11) were colonized with Legionella. These were all supplied with municipal drinking water that contained free chlorine as a residual disinfectant. In these contaminated hospitals, the proportion of sites testing positive was inversely correlated with free residual chlorine concentration (P=.01). In all hospitals, hot-water temperatures were too low to inhibit Legionella growth.

CONCLUSIONS

The increase in reporting of nosocomial legionnaires' disease was attributable to increased use of urinary antigen tests; prior cases may have gone unrecognized. Risk of legionnaires' disease in hospital patients was better predicted by the proportion of water-system sites testing positive for Legionella than by the measured concentration of Legionella bacteria. Use of monochloramine by municipalities for residual drinking water disinfection may help prevent legionnaires' disease.

Legionella infection and control in occupational and environmental health

This review describes the microbiological characteristics of Legionella species, their habits in the environment, source and route of infection, pathogenesis, symptoms and treatment of legionellosis, and disease outbreaks worldwide. We also describe prevention measures to deal with this organism in the work environment. Particularly in Japan, the present measures and countermeasures against legionellosis are inadequate when compared with those Europe and the United States because occupational and environmental medicine in Japan has not been structured from a microbiological viewpoint. As a result, workplace inspections have not covered cooling towers. We surveyed the cooling towers provided in work environments and in hospitals in Kitakyushu City for contamination by Legionella species. The surveillance definitely revealed that we are surrounded by cooling towers contaminated with Legionella. We conclude that in Japan, occupational and environmental physicians should routinely monitor the water in cooling towers.

Ventilator-associated pneumonia

Mechanically ventilated patients are at a substantially higher risk for developing nosocomial pneumonia. Overall, there is a relatively constant 1&!TN!150;3% risk per day of developing pneumonia while receiving mechanical ventilation. The sensitivity and specificity of clinical criteria alone for diagnosis of ventilator-associated pneumonias (VAP) is low. Several techniques have been developed to sample and quantitate the lower respiratory tract to improve the diagnostic yield. Gram-negative bacillary pneumonias account for the majority of the VAP. Strategies for prevention of VAP such as use of sucralfate for stress ulcer prophylaxis and selective decontamination of the digestive tract have been the focus of many clinical studies. Cost-effective preventive measures are needed to combat the increasing antimicrobial resistance, growing population of immunocompromised patients and increasing number of mechanically ventilated patients.

Colonization of transplant unit water supplies with Legionella and protozoa: precautions required to reduce the risk of legionellosis

Organ transplant recipients and other immunosuppressed patients are known to be at increased risk of nosocomial Legionnaires' disease. Although the ecology of Legionella in hospital water storage and distribution systems (including a protozoonotic relationship with free-living protozoa) has been well documented, little is known regarding the quality of water supplied to high-risk units. Hot- and cold-water samples (two first draw and one run to waste for 5 min) were taken from 69 (85%) of the 81 United Kingdom organ transplant units (31 renal, 24 bone marrow, nine cardiopulmonary and five liver transplant units) and cultured for Legionella and protozoa. Legionella spp. were isolated from the water supplies of 38 (55%) units and Legionella pneumophila from 31 (45%). The blue-white fluorescent group of Legionella (Legionella gormanii, Legionella bozemanii and others) was isolated from 18 (26%) units. Free-living protozoa were isolated from 47 units (68%) and genera of the protozoa known to permit the intracellular growth of Legionella (PGIGL), from 40 units (58%). Possible associations between Legionella and the variables Protozoa; PGIGL; water pH; and circulating water temperature (recorded after running to waste for 5 min) were examined by logistic regression analysis. In cold-water supplies, a significant association was found between the isolation of Legionella and PGIGL (P = 0.032; OR = 1.81; 95% CI 1.1-3.1). In hot-water supplies, an inverse association was found between the isolation of Legionella and circulating water temperature (P = 0.034; OR = 1.0719 per degree C; 95% CI 1.0052-1.1432). (We failed to isolate Legionella when the circulating hot water was > 58 degrees C. No other associations were significant. We recommend the active surveillance of water quality in high-risk patient areas, and that transplant units, either with a history of nosocomial Legionnaires' disease, or where active surveillance indicates a persistently high Legionella colony count, take remedial action. The quality of cold water may be improved by provision of a dedicated supply taken directly from the incoming mains; and of hot water by the use of a dedicated calorifier, able to maintain a minimum circulating hot water return temperature of 60 degrees C.

Development of a new seminested PCR method for detection of Legionella species and its application to surveillance of legionellae in hospital cooling tower water

The presence of PCR inhibitors in water samples is well known and contributes to the fact that a practical PCR assay has not been developed for legionella surveillance. In this study, we devised a new seminested PCR assay for detection of Legionella spp. in water samples as a means of overriding the PCR inhibitors without loss of sensitivity. The seminested PCR assay utilized primers to amplify the 16S rRNA gene (LEG primers) of 39 Legionella spp. The assay was specific to legionellae, and the sensitivity was 1 fg of extracted Legionella DNA in laboratory examination. To evaluate the feasibility and sensitivity of the PCR assay in identifying the presence of legionellae, it was used to survey Legionella contamination in the water of 49 cooling towers of 32 hospitals. A commercially available EnviroAmp Legionella kit and a culture method were also used in the survey for comparison with the seminested PCR assay. The detection rates of legionellae in the samples were 91.8% (45 of 49) by the PCR assay and 79.5% (39 of 49) by the culture method. The EnviroAmp kit revealed that 30.6% of the water samples (15 of 49) contained inhibitors of the PCR amplification. However, the seminested PCR assay could produce the Legionella-specific DNA bands in 14 of the 15 samples. Although 8 of the 14 samples were positive in the first-step PCR, 6 of the 14 samples became positive in the second-step PCR. These results suggest that the effect of PCR inhibitors in samples, if any, can be reduced because of the dilution of the sample in the second-step PCR and that sensitivity of detection can be increased by the second-step PCR. Thus, the seminested PCR assay with LEG primers to amplify the 16S rRNA gene of 39 Legionella spp. was a practical and sensitive method to detect Legionella spp. in water samples.

Emerging Infectious Diseases in the Institutional Setting: Another Hot Zone

During the closing years of the 20th century, there has been an unprecedented number of newly recognized infectious agents and a resurgence of infectious diseases only recently thought to be conquered. These problems have been compounded by the increasing number of pathogens that have evolved resistance to antimicrobial agents. Hospitals and other institutional settings occupy a pivotal niche in the emergence of infectious agents due to factors such as the large concentrations of ill and immunocompromised persons, evolving technologies in healthcare settings, routine breeches of host defense mechanisms, and frequent use of antimicrobial agents. Any comprehensive strategy to address emerging infectious diseases must incorporate provisions for healthcare settings, including efforts to enhance surveillance, response capacity, training, education, applied research, and routine implementation of prevention measures.

Legionellosis linked with a hotel car park--how many were infected?

An outbreak of legionellosis associated with a hotel in Sydney, Australia, and the subsequent epidemiological and environmental investigations are described. Four cases of Legionnaires' disease were notified to the Public Health Unit. A cross-sectional study of 184 people who attended a seminar at the hotel was carried out. Serological and questionnaire data were obtained for 152 (83%) of these. Twenty-eight (18%) respondents reported symptoms compatible with legionellosis. Thirty-three subjects (22%) had indirect fluorescent antibody (IFA) titres to Legionella pneumophila serogroup 1 (Lp-1) of 128 or higher. The only site which those with symptoms of legionellosis and IFA titre > or = 128 were more likely to have visited than controls was the hotel car park (adjusted odds ratio [OR] 14.7, 95% confidence interval [CI]: 1.8-123.1). Those with symptoms compatible with legionellosis, but whose IFA titres were < 128 were also more likely to have visited the hotel car park (adjusted OR 4.4, 95% CI: 1.5-12.9). Seroprevalence of Lp-1 antibodies was higher in those who attended the seminar than in a population sample of similar age. Findings suggested that the 4 cases represented a small fraction of all those infected, and highlighted difficulties in defining illness caused by Lp-1 and in interpreting serology.

Biofilm and the dental office

The author provides a brief overview of the basic processes involved in biofilm formation and explores the implications these biofilms have for health care facilities such as hospitals and dental offices. Included with this article are suggestions dentists may consider for improving water quality and a white paper on waterlines adopted by the ADA.

A paint incorporating silver to control mixed biofilms containing Legionella pneumophila

A three-stage chemostat containing a mixed consortium of microorganisms, including Legionella pneumophila, was used to determine the suitability of a silver-containing paint to control biofouling in water systems. The paint was efficient in controlling total surface colonisation by heterotrophic microorganisms and growth of the pathogen over a 2-week period. Biodiversity was limited in the presence of the silver paint and this was thought to help control L. pneumophila numbers. Glass control tiles suspended alongside the silver painted tiles also had reduced colonisation for the 2-week period, suggesting that low levels of silver leached from the paint surface. This loss of silver was confirmed since the inhibition of biofouling and inclusion of the pathogen was not maintained after the 2-week period. Although this paint was unsuitable for controlling biofouling over extended time periods, the data suggest that a reformulated paint or electrochemical method of introducing silver ions may be successful.

Legionnaires' disease outbreak, Fairfield 1992: public health aspects

An investigation of an outbreak of Legionnaires' disease in 1992 in Fairfield, a municipality of Sydney, was carried out to determine the source of the outbreak. Cases of Legionnaires' disease with onset of symptoms between 11 and 20 April 1992 were included. Definite cases were individuals with a history consistent with Legionnaires' disease, confirmed by direct fluorescent antibody testing plus serology or culture. There were two control groups: patients admitted to the same hospital as the cases, matched for age and sex, and patients admitted to hospital with a presumptive diagnosis of legionnaires' disease, in whom the diagnosis was subsequently excluded. There were 26 definite cases with onset of symptoms between 11 and 20 April 1992. Six (23 per cent) died. Twenty-two cases (85 per cent) reported visiting the Fairfield business district during the ten days prior to the onset of symptoms. They were 20 times more likely to have visited Fairfield than were matched controls. Matching of Legionella pneumophila serogroup 1 from environmental and clinical samples was achieved by cytogenetic fingerprinting. Fourteen cases were linked to a single environmental sample. The epidemiological findings were consistent with a point source of Legionella in the Fairfield business district. It is most likely that the exposure occurred on 10 April 1992.

Fatal nosocomial Legionnaires' disease: relevance of contamination of hospital water supply by temperature-dependent buoyancy-driven flow from spur pipes

The investigation, epidemiology, and effectiveness of control procedures during an outbreak of Legionnaires' disease involving three immunosuppressed patients are described. The source of infection appeared to be a network of fire hydrant spurs connected directly to the incoming hospital mains water supply. Removal of these hydrants considerably reduced, but failed to eliminate, contamination of water storage facilities. As an emergency control procedure the incoming mains water was chlorinated continuously. Additional modifications to improve temperature regulation and reduce stagnation also failed to eliminate the legionellae. A perspex test-rig was constructed to model the pre-existing hospital water supply and storage system. This showed that through the hydraulic mechanism known as 'temperature buoyancy', contaminated water could be efficiently and quickly exchanged between a stagnant spur pipe and its mains supply. Contamination of hospital storage tanks from such sources has not previously been considered a risk factor for Legionnaires' disease. We recommend that hospital water storage tanks are supplied by a dedicated mains pipe without spurs.

Nosocomial Legionnaires' disease in England and Wales, 1980-92

Two hundred and eighteen nosocomial cases of Legionnaires' disease with 68 deaths were reported to the National Surveillance Scheme for Legionnaires Disease between 1980 and 1992, representing 15% of the reported infections acquired in England and Wales. Twenty-two nosocomial outbreaks accounted for 135 (62%) of these cases, the remainder occurring as single cases either in hospitals where other single cases or outbreaks had been reported in different years or as 'sporadic' cases in hospitals from which no other cases were reported. A clinical history prior to onset of Legionnaires' disease was available for 124 patients, 61 of whom had undergone recent transplant therapy or were immunosuppressed for other reasons. Sixty cases (27%) were diagnosed by culture of the organism and isolates from 56 patients were typed; 25 (42%) were non L. pneumophila serogroup 1 infections. Methods for prevention and control of nosocomial outbreaks are discussed, in particular the susceptibility to Legionnaires' disease of certain groups of hospital patients.