Compost and Legionella longbeachae : an emerging infection?

Human disease caused by Legionella species is dominated by Legionella pneumophila, the main causative agent in cases of Legionnaires’ disease. However, other species are known to cause infection, for example, Legionella longbeachae causes an equivalent number of cases of disease as L. pneumophila in Australia and New Zealand. Infection with L. longbeachae is commonly associated with exposure to composts and potting soils, and cases of infection with this organism have been increasing in Europe over the past ten years. The increase in incidence may be linked to factors such as increased awareness of clinical presentation, or due to changing formulation of growing media, although it should be noted that the presence of Legionella species in growing media does not correlate with the number of cases currently seen. This is likely due to the variables associated with infection, for example, host factors such as smoking or underlying health conditions, or difference in growing media storage or climate, especially warm humid conditions, which may affect survival and growth of these organisms in the growing media environment. There are numerous unknowns in this area and collaboration between growing media manufacturers and researchers, as well as more awareness among diagnosing clinicians, laboratory staff and the general public is necessary to reduce risk. More research is needed before definitive conclusions can be drawn: L. pneumophila research currently dominates the field and it is likely that the overreliance on diagnostic techniques such as the urinary antigen test, which is specific for L. pneumophila Sg 1, is detrimental to the diagnosis of L. longbeachae infection

The use of minimum selectable concentrations (MSCs) for determining the selection of antimicrobial resistant bacteria

The use of antimicrobial compounds is indispensable in many industries, especially drinking water production, to eradicate microorganisms. However, bacterial growth is not unusual in the presence of disinfectant concentrations that would be typically lethal, as bacterial populations can develop resistance. The common metric of population resistance has been based on the Minimum Inhibitory Concentration (MIC), which is based on bacteria lethality. However, sub-lethal concentrations may also select for resistant bacteria due to the differences in bacterial growth rates. This study determined the Minimal Selective Concentrations (MSCs) of bacterial populations exposed to free chlorine and monochloramine, representing a metric that possibly better reflects the selective pressures occurring at lower disinfectant levels than MIC. Pairs of phylogenetically similar bacteria were challenged to a range of concentrations of disinfectants. The MSCs of free chlorine and monochloramine were found to range between 0.021 and 0.39 mg L-1, which were concentrations 1/250 to 1/5 than the MICs of susceptible bacteria (MICsusc). This study indicates that sub-lethal concentrations of disinfectants could result in the selection of resistant bacterial populations, and MSCs would be a more sensitive indicator of selective pressure, especially in environmental systems

Antibiotic resistant bacteria found in municipal drinking water

Multidrug resistant bacteria in water supply systems have been emerging as a growing public health concern. Many factors affect the source and fate of these bacteria. However, conditions in the distribution systems may contribute in the dispersion of resistance genes among bacterial populations. Through the process of lateral gene transfer, resistance genetic material can be exchanged between species in the microbial population, intensifying the problem of resistance genes. The main aim of this study was to investigate the diversity of microorganisms in tap-water in Glasgow, Scotland, and the occurrence of certain antibiotic resistance genes and gene-transfer mechanisms. Results show that antibiotic resistant bacteria exist at the consumers’ end of the distribution system, some of which also contain integrase genes, which can aid in the dispersion of resistance genes. Presence of such microorganisms indicates that further investigations should be taken to assess the risks to public health

Rapid selection of antimicrobial resistant bacteria in complex water systems by chlorine and pipe materials

Antimicrobial resistance is a major health issue induced by the overuse of antibiotics and disinfection reagents, e.g. chlorine. Resistant bacteria thus occur in water supply systems, and they transfer genes to other microbial populations, including pathogens. Treatment and inactivation of resistant bacteria are difficult in complex systems because the behaviour of resistant bacteria in such systems is poorly known, as most previous investigations are commonly performed in pure media. Therefore, we tested here the effect of 0.5 mg/mL chlorine and pipe materials made of polyvinyl chloride (PVC), copper and cement, on microbial populations in biofilms, during 5 days. Bacterial survival was monitored by viable counts, and resistant genes were analysed by quantitative polymerase chain reaction (qPCR). Results show that, in 56% of the cases, resistant bacteria became immediately enriched into biofilms due to chlorine exposure. Higher proportion of resistant bacteria were found in biofilms on PVC and copper pipes. Our findings imply that resistant microbial strains are very rapidly selected and that the pipe material has an influence on microbial selection

Is the HCV-HIV co-infection prevalence amongst injecting drug users a marker for the level of sexual and injection related HIV transmission?

BACKGROUND: Amongst injecting drug users (IDUs), HIV is transmitted sexually and parenterally, but HCV is transmitted primarily parenterally. We assess and model the antibody prevalence of HCV amongst HIV-infected IDUs (denoted as HCV-HIV co-infection prevalence) and consider whether it proxies the degree of sexual HIV transmission amongst IDUs. METHODS: HIV, HCV and HCV-HIV co-infection prevalence data amongst IDU was reviewed. An HIV/HCV transmission model was adapted. Multivariate model uncertainty analyses determined whether the model's ability to replicate observed data trends required the inclusion of sexual HIV transmission. The correlation between the model's HCV-HIV co-infection prevalence and estimated proportion of HIV infections due to injecting was evaluated. RESULTS: The median HCV-HIV co-infection prevalence (prevalence of HCV amongst HIV-infected IDUs) was 90% across 195 estimates from 43 countries. High HCV-HIV co-infection prevalences (>80%) occur in most (75%) settings, but can be lower in settings with low HIV prevalence (0.75). The model without sexual HIV transmission reproduced some data trends but could not reproduce any epidemics with high HIV/HCV prevalence ratios (>0.85) or low HCV-HIV co-infection prevalence (10%. The model with sexual HIV transmission reproduced data trends more closely. The proportion of HIV infections due to injecting correlated with HCV-HIV co-infection prevalence; suggesting that up to 80/60/90%. CONCLUSION: Substantial sexual HIV transmission may occur in many IDU populations; HCV-HIV co-infection prevalence could signify its importance

Using participatory methods to design an mHealth intervention for a low income country, a case study in Chikwawa, Malawi

This research was conducted by the Scotland Chikwawa Health Initiative. We would like to thank Sothin Ziba and Rossanie Daudi for their contribution to the facilitation of the focus group discussions. This study was funded by the Scottish Government grant MW22.Peer reviewedPublisher PD

Social capital insights from healthy settings needs assessment in Malawi

Despite global health improvements, substantial challenges in social determinants of health and poverty remain in rural communities in low-income countries. Public health theorists suggest that communities with high social capital are less vulnerable to such challenges and more likely to participate in community development. This research examines levels of social capital amongst rural communities in southern Malawi through data gathered as part of a participatory needs assessment for a Healthy Settings project, and discusses the potential benefits of having access to such data before project implementation. Social capital data was collected during 108 focus group discussions in 18 communities (split by gender, age, status) by adapting an existing mixed methods measurement tool, the Schutte tool. Five indicators were measured: sense of belonging, friendship, reliance, ability to work together and influence. Mean results showed all 18 communities had medium-high levels of social capital. Means from each group in the 18 communities highlighted the lowest social capital among the youth groups and the highest with the leaders. A more detailed breakdown highlighted that all groups had a strong sense of belonging to the community, while youth and women had lower social capital levels in terms of influence over local decisions and ability to rely on other community members. Incorporating social capital tools into community health needs assessments in low-income settings provides a valuable overview of community dynamics before project implementation, and Monitoring & Evaluation indicators which allow changes in social capital to be measured at different stages of the project

Process evaluation of "the Hygienic Family" intervention : a community-based water, sanitation and hygiene project in rural Malawi

Process evaluations of environmental health interventions are often under-reported and under-utilized in the development of future programs. The “Hygienic Family” intervention targeted improvements in hygiene behaviors of caregivers with under five-year-old children in rural Malawi. Delivered through a combination of open days, cluster meetings, household visits, and prompts, data were collected from two intervention areas for ten months. A process evaluation framework provided indicators that were measured through intervention implementation and expenditure reports, focus groups discussions, interviews, and household surveys. The collected data assessed the intervention fidelity, dose, reach, acceptability, impact, and cost. Results indicated that all planned hygiene promotion messages were delivered, and study participants were better reached primarily through household visits (78% attended over 75% of the intervention) than cluster meetings (57% attended over 75% of the intervention). However, regression found that the number of household visits or cluster meetings had no discernible effect on the presence of some household hygiene proxy indicators. Intervention implementation cost per household was USD 31.00. The intervention delivery model provided good fidelity, dose, and reach and could be used to strengthen the scope of child health and wellbeing content. The intensive face-to-face method has proven to be effective but would need to be adequately resourced through financial support for community coordinator remuneration

Measurement of diesel combustion-related air pollution downwind of an experimental unconventional natural gas operations site

Background & aim: Unconventional natural gas (UNG) extraction activities have considerable potential to affect air quality. However, there are few published quantitative observations of the magnitude of such impacts. To provide context, we compared measured exposures to diesel engine exhaust close to industrial fracking equipment at an UNG training simulation site in Łowicz, Poland to pedestrian exposures to traffic-related air pollution in the city centre of Glasgow, UK. Methods: We made mobile and static measurements at varying distances from sources in both of the above locations with a portable aethalometer (Aethlabs AE51) for black carbon (BC) and portable monitors (Aeroqual Series-500) for nitrogen dioxide (NO₂) and ozone (O₃). Duplicate BC measurements were compared with NO₂ observations, after correction of the NO₂ sensor response for O₃ interference effects. Results: Duplicate BC instruments provided similar real-time measurements (r = 0.92), which in turn were relatively highly correlated with NO₂ observations at 5-min temporal resolution at the UNG experimental site (r = 0.75) and on the walking route in Glasgow city centre (r = 0.64) suggesting common diesel sources for NO₂ and BC in both locations. Average BC and NO₂ concentrations measured approximately 10 m downwind of diesel fracking pumps were 11 and 113 μg/mᶟ respectively. These concentrations were approximately 37 times and 4 times higher than upwind background BC and NO₂ concentrations at the site; and approximately 3 times higher than average BC and NO₂ concentrations measured in traffic influenced areas in Glasgow. Conclusions: Marked elevations of BC and NO₂ concentrations were observed in downwind proximity to industrial fracking equipment and traffic sources. This suggests that exposure to diesel engine exhaust emissions from fracking equipment may present a significant risk to people working on UNG sites over extended time periods. The short time resolution of the portable instruments used enabled identification of likely sources of occupational and environmental exposure to combustion-related air pollutants