Samuel Collins

Insidious risk of severe mycobacterium chimaera infection in cardiac surgery patients

Background. An urgent UK investigation was launched to assess risk of invasive Mycobacterium chimaera infection in cardiothoracic surgery and a possible association with cardiopulmonary bypass heater-cooler units following alerts in Switzerland and The Netherlands. Methods. Parallel investigations were pursued: (1) identification of cardiopulmonary bypass–associated M. chimaera infection through national laboratory and hospital admissions data linkage; (2) cohort study to assess patient risk; (3) microbiological and aerobiological investigations of heater-coolers in situ and under controlled laboratory conditions; and (4) whole-genome sequencing of clinical and environmental isolates. Results. Eighteen probable cases of cardiopulmonary bypass–associated M. chimaera infection were identified; all except one occurred in adults. Patients had undergone valve replacement in 11 hospitals between 2007 and 2015, a median of 19 months prior to onset (range, 3 months to 5 years). Risk to patients increased after 2010 from <0.2 to 1.65 per 10000 person-years in 2013, a 9-fold rise for infections within 2 years of surgery (rate ratio, 9.08 [95% CI, 1.81–87.76]). Endocarditis was the most common presentation (n = 11). To date, 9 patients have died. Investigations identified aerosol release through breaches in heater-cooler tanks. Mycobacterium chimaera and other pathogens were recovered from water and air samples. Phylogenetic analysis found close clustering of strains from probable cases. Conclusions. We identified low but escalating risk of severe M. chimaera infection associated with heater-coolers with cases in a quarter of cardiothoracic centers. Our investigations strengthen etiological evidence for the role of heater-coolers in transmission and raise the possibility of an ongoing, international point-source outbreak. Active management of heater-coolers and heightened clinical awareness are imperative given the consequences of infection.

Evaluation of Legionella real‐time PCR against traditional culture for routine and public health testing of water samples

To evaluate the usefulness of Legionella qPCR alongside traditional culture for enumeration of Legionella from water samples as part of both routine and public health investigation testing.

Comments on Whiley Legionella Risk Management and Control in Potable Water Systems: Argument for the Abolishment of Routine Testing. Int. J. Environ. Res. Public Health 2017, 14, 12

In their recent article, Whiley makes an interesting case for the abolishment of routine testing in Legionella risk management and control plans. Here, we present our views regarding this suggestion, drawing upon our own experiences in the UK. We urge caution against the removal of routine monitoring from guidelines due to the impending public health risks that would result.

Comment on Montagna, et al. Evaluation of Legionella air contamination in healthcare facilities by different sampling methods: An Italian multicenter study. Int. J. Environ. Res. Public Health 2017, 14, 670

In their recent article, Montagna et al. describe a multicenter study investigating the presence ofLegionella in water and air samples of Italian healthcare facilities [1]. This is an interesting study thathighlights some important gaps in our basic understanding of Legionella.One of the limitations of the study regarded the lack of information on the tap outlets (e.g., designof tap, flow rates, temperature of the water) and the bathrooms (ambient temperature, humidity, airmovements, etc.) as these factors can influence aerosols produced and may facilitate the interpretationof aerosol data. For future studies it may be advantageous to characterise the aerosols produced bythese outlets, using for example an aerodynamic particle sizer (APS) [2]. Furthermore, caution shouldbe advised as some of the conclusions from the culture data are based on the detection of just 1 colonyforming unit (CFU)/m

High prevalence of Legionella in non-passenger merchant vessels

There is a paucity of information on the risk from potable water in non-passenger merchant vessels (NPMVs) particularly with regard to Legionella and other bacteria. This retrospective study examined water samples from 550 NPMVs docked in eight UK ports. A total of 1027 samples from 412 NPMVs were examined for total aerobic colony counts (ACC), coliforms, Escherichia coli and enterococci; 41% of samples yielded ACC above the action level (>1 × 103 c.f.u./ml) and 4·5% contained actionable levels (>1 c.f.u./100 ml) of faecal indicator bacteria. Eight hundred and three samples from 360 NPMVs were cultured specifically for Legionella and 58% of vessels proved positive for these organisms with 27% of samples showing levels greater than the UK upper action limit of 1 × 103 c.f.u./l. Cabin showers (49%) and hospital shower (45%) were frequently positive. A subset of 106 samples was analysed by quantitative polymerase chain reaction for Legionella and identified a further 11 Legionella-positive NPMVs, returning a negative predictive value of 100%. There was no correlation between NPMV age or size and any microbial parameters (P > 0·05). Legionella pneumophila serogroup 1 was isolated from 46% of NPMVs and sequence-based typing of 17 isolates revealed four sequence types (STs) previously associated with human disease. These data raise significant concerns regarding the management of microbial and Legionella risks on board NPMVs and suggest that better guidance and compliance are required to improve control.

Scoping studies to establish the capability and utility of a real-time bioaerosol sensor to characterise emissions from environmental sources

A novel dual excitation wavelength based bioaerosol sensor with multiple fluorescence bands called Spectral Intensity Bioaerosol Sensor (SIBS) has been assessed across five contrasting outdoor environments. The mean concentrations of total and fluorescent particles across the sites were highly variable being the highest at the agricultural farm (2.6 cm-3 and 0.48 cm-3, respectively) and the composting site (2.32 cm-3 and 0.46 cm-3, respectively) and the lowest at the dairy farm (1.03 cm-3 and 0.24 cm-3, respectively) and the sewage treatment works (1.03 cm-3 and 0.25 cm-3, respectively). In contrast, the number-weighted fluorescent fraction was lowest at the agricultural site (0.18) in comparison to the other sites indicating high variability in nature and magnitude of emissions from environmental sources. The fluorescence emissions data demonstrated that the spectra at different sites were multimodal with intensity differences largely at wavelengths located in secondary emission peaks for λex 280 and λex 370. This finding suggests differences in the molecular composition of emissions at these sites which can help to identify distinct fluorescence signature of different environmental sources. Overall this study demonstrated that SIBS provides additional spectral information compared to existing instruments and capability to resolve spectrally integrated signals from relevant biological fluorophores could improve selectivity and thus enhance discrimination and classification strategies for real-time characterisation of bioaerosols from environmental sources. However, detailed lab-based measurements in conjunction with real-world studies and improved numerical methods are required to optimise and validate these highly resolved spectral signatures with respect to the diverse atmospherically relevant biological fluorophores.

Chemical warfare agent simulants for human volunteer trials of emergency decontamination: A systematic review

Incidents involving the release of chemical agents can pose significant risks to public health. In such an event, emergency decontamination of affected casualties may need to be undertaken to reduce injury and possible loss of life. To ensure these methods are effective, human volunteer trials (HVTs) of decontamination protocols, using simulant contaminants, have been conducted. Simulants must be used to mimic the physicochemical properties of more harmful chemicals, while remaining non‐toxic at the dose applied. This review focuses on studies that employed chemical warfare agent simulants in decontamination contexts, to identify those simulants most suitable for use in HVTs of emergency decontamination. Twenty‐two simulants were identified, of which 17 were determined unsuitable for use in HVTs. The remaining simulants (n = 5) were further scrutinized for potential suitability according to toxicity, physicochemical properties and similarities to their equivalent toxic counterparts. Three suitable simulants, for use in HVTs were identified; methyl salicylate (simulant for sulphur mustard), diethyl malonate (simulant for soman) and malathion (simulant for VX or toxic industrial chemicals). All have been safely used in previous HVTs, and have a range of physicochemical properties that would allow useful inference to more toxic chemicals when employed in future studies of emergency decontamination systems.

Assessing organism viability and interpreting genomic unit versus colony forming unit data for water and food borne microorganisms, such as Legionella, Campylobacter, Salmonella , and Listeria

New molecular-based methods for the detection of pathogens in food and water have a number of benefits over traditional culture-based assays, including ability to detect and enumerate pathogens rapidly, in real-time, the ability to negatively screen samples without the need for culture, the power to link detection with specific strain identification and confirmation, and the opportunity to detect only viable cells. However, with the introduction of such techniques, it is important to have an understanding of what exactly they are detecting, their limitations, and how the data from such assays can be interpreted. This chapter provides an outline and understanding of molecular methods used to evaluate the microbiological quality of water and food, with particular emphasis on real-time polymerase chain reaction (PCR), including quantitative real-time PCR. Issues addressed will include determining whether the microorganisms detected are viable, and the importance of correct interpretation of PCR-based results. The chapter will also discuss the steps that need to be taken by the food and water testing industry to ensure robust and meaningful assays are developed and utilized correctly, in order to provide accurate and reliably interpreted results in a timely manner to stakeholders.