Genome Sequencing Links Persistent Outbreak of Legionellosis in Sydney (New South Wales, Australia) to an Emerging Clone of Legionella pneumophila Sequence Type 211.

The city of Sydney, Australia, experienced a persistent outbreak of Legionella pneumophila serogroup 1 (Lp1) pneumonia in 2016. To elucidate the source and guide public health actions, the genomes of clinical and environmental Lp1 isolates recovered over 7 weeks were examined. A total of 48 isolates from human cases and cooling towers were sequenced and compared using single-nucleotide polymorphism (SNP)-based core-genome multilocus sequencing typing (MLST) and pangenome approaches. All three methods confirmed phylogenetic relatedness between isolates associated with outbreaks in the Central Business District (CBD) in March and May and those in suburb 1. These isolates were designated the "main cluster" and consisted of isolates from two patients from the CBD March outbreak, one patient and one tower isolate from suburb 1, and isolates from two cooling towers and three patients from the CBD May outbreak. All main cluster isolates were sequence type 211 (ST211), which previously has only been reported in Canada. Significantly, pangenome analysis identified mobile genetic elements containing a unique type IV A F-type secretion system (T4ASS), which was specific to the main cluster, and cocirculating clinical strains, suggesting a potential mechanism for increased fitness and persistence of the outbreak clone. Genome sequencing enabled linking of the geographically dispersed environmental sources of infection among the spatially and temporally coinciding cases of legionellosis in a highly populated urban setting. The discovery of a unique T4ASS emphasizes the role of genome recombination in the emergence of successful Lp1 clones.IMPORTANCE A new emerging clone has been responsible for a prolonged legionellosis outbreak in Sydney, Australia. The use of whole-genome sequencing linked two outbreaks thought to be unrelated and confirmed the outliers. These findings led to the resampling and subsequent identification of the source, guiding public health actions and bringing the outbreak to a close. Significantly, the outbreak clone was identified as sequence type 211 (ST211). Our study reports this ST in the Southern Hemisphere and presents a description of ST211 genomes from both clinical and environmental isolates. A unique mobile genetic element containing a type IV secretion system was identified in Lp1 ST211 isolates linked to the main cluster and Lp1 ST42 isolates that were cocirculating at the time of the outbreak.

A mild outbreak of gastroenteritis in long-term care facility residents due to Clostridium perfringens, Australia 2009.

INTRODUCTION: Clostridium perfringens food poisoning is a commonly cited cause of gastroenteritis outbreaks among elderly long-term care facility (LTCF) residents, yet little is known about the natural history of disease in this vulnerable group. In July 2009, an investigation into diarrheal illness among LTCF residents was commenced. METHODS: An environmental health investigation and retrospective cohort study were undertaken to confirm the outbreak, to identify a source and mode of transmission, and to implement public health measures to prevent further cases. Menu listings and food safety program details were obtained and food-handling practices were observed. Clinical notes of all residents were reviewed. A possible case was defined as any resident developing one or more acute loose stool episodes between the evenings of 23 July and 27 July. RESULTS: Fifty-two residents (41%) had been ill with diarrhea, and eight residents had fecal samples positive for C. perfringens enterotoxin. LTCF staff failed to perform routine temperature checks on hot foods before the outbreak. A sweet-and-sour pork lunch served on 23 July was implicated in causing residents' illness, but no residual food remained for microbiological testing. Independent associations with illness were demonstrated among residents living in two wings of the facility that received a standard level of service, whereas an inverse association with illness was shown among residents living in an "extra service" wing. Male residents were also more likely to become ill. Illness was mild with case patients reporting a median of two loose stools (range 1-12). CONCLUSIONS: C. perfringens is an important cause of both foodborne and nonfoodborne gastroenteritis outbreaks in LTCF, but may be missed due to the often mild nature of illness. This investigation highlights the potential burden of C. perfringens disease among vulnerable LTCF populations. To prevent C. perfringens outbreaks, facilities must adhere to food safety plans and ensure high standards of infection control practice.

It's enough to make you sick: the impact of racism on the health of Aboriginal Australians.

BACKGROUND: Experience of interpersonal racism has been neglected as a mechanism by which inequalities between Aboriginal and non-Aboriginal people are created and maintained. METHODS: Cross-sectional survey of randomly selected residents of a rural Australian town (n=639). Interpersonal racism was measured by two questions on experiences in the past four weeks of negative racially based treatment that evoked an emotional or physical response. Health was measured with the mental and physical health component scores of the Short-Form 12 and self-reported fair or poor general health. Linear and logistic regressions modelled the effects of interpersonal racism on health, controlling for age, sex, socio-economic status and Aboriginality. FINDINGS: The 183 Aboriginal respondents had lower health component scores, were more than twice as likely to report fair-to-poor general health (34% compared with 17%, p<0.001), and 2.6 to 5.0 times more likely to report negative racially based treatment. Demographic and socio-economic characteristics were not associated with reporting negative racially based treatment. After controlling for other variables, Aboriginal respondents who reported negative treatment were more likely to have poor health on all three measures. Non-Aboriginal respondents who reported experiencing negative treatment had lower mental health component scores. IMPLICATIONS: Experiencing racist treatment should be recognised as a social determinant of health. Improved health care and other initiatives may not eliminate health inequalities in the absence of fundamental changes in how non-Aboriginal people behave towards Aboriginal people.