Geoffrey G Hogg

Nationwide study of haemolytic uraemic syndrome: clinical, microbiological, and epidemiological features

AIMS To establish the incidence and aetiology of haemolytic uraemic syndrome (HUS) in Australia and compare clinical and microbial characteristics of sporadic and outbreak cases. METHODS National active surveillance through the Australian Paediatric Surveillance Unit with monthly case notification from paediatricians, July 1994 to June 1998. Children under 15 years presenting with microangiopathic haemolytic anaemia, thrombocytopenia, and acute renal impairment were identified. RESULTS Ninety eight cases were identified (incidence 0.64 per 105 children <15 years/annum and 1.35 per 105 children <5 years/annum). Eighty four were associated with diarrhoea (64 sporadic, 20 constituting an outbreak) and 14 were atypical. Shiga toxin producingEscherichia coli (STEC) O111:H− was the most common isolate in sporadic HUS and caused the outbreak. However O111:H− isolates from outbreak and sporadic cases differed in phage type and subtyping by DNA electrophoresis. STEC isolates from sporadic cases included O26:H−, O113:H21, O130:H11, OR:H9, O157:H−, ONT:H7, and ONT:H−. STEC O157:H7 was not isolated from any case. Only O111:H− isolates produced both Shiga toxins 1 and 2 and possessed genes encoding E coli attaching and effacing gene (intimin) and enterohemolysin. Outbreak cases had worse gastrointestinal and renal disease at presentation and more extrarenal complications. CONCLUSIONS Linking national surveillance with a specialised laboratory service allowed estimation of HUS incidence and provided information on its aetiology. In contrast to North America, Japan, and the British Isles, STEC O157:H7 is rare in Australia; however, non-O157:H7 STEC cause severe disease including outbreaks. Disease severity in outbreak cases may relate to yet unidentified virulence factors of the O111:H− strain isolated.

Cerebrospinal fluid shunt infections in children.

We reviewed cerebrospinal fluid (CSF) shunt infections treated in the Royal Childrens Hospital, Melbourne from 1981 to 1991. Forty-one episodes of CSF shunt infection were found after 900 shunt operations, an infection rate of 4.5%. Clinical symptoms were nonspecific in 31.7% of episodes, and in 17.1% of episodes the initial CSF sample was normal on microscopy and biochemistry, although a pathogen was isolated on culture. Most episodes occurred within 4 months of the last operation on the shunt, the exception being infections caused by Haemophilus influenzae. Four patients died during treatment, but none could be attributed to infection alone. Treatment of suspected CSF shunt infection should not be withheld because of lack of firm clinical diagnosis or normal CSF microscopy, and episodes occurring more than 4 months after the last operation on the CSF shunt should receive antibiotic cover for H. influenzae.

Prevalence of enteric pathogens among community based asymptomatic individuals

Background and Aims : The objective of this study was to describe the prevalence of pathogenic microorganisms in asymptomatic individuals in a community study in Melbourne, Australia.

Emergence of a Ribotype 244 Strain of Clostridium difficile Associated With Severe Disease and Related to the Epidemic Ribotype 027 Strain

BACKGROUND We identified 12 patients with Clostridium difficile infection between July 2011 and March 2012 from whom an unusual C. difficile strain was isolated. This strain had a single-nucleotide deletion of the tcdC gene at position 117 and binary toxin genes, which are characteristic of the hypervirulent ribotype (RT) 027 strain. METHODS A retrospective cohort study of 12 patients infected with C. difficile RT244 and 24 patients infected with non-RT244/non-RT027 strains matched for place of diagnosis and time of collection of specimen was performed. We performed whole-genome sequencing to understand the relationship of the RT244 strain to other C. difficile strains and further understand its virulence potential. RESULTS Clostridium difficile RT244 was associated with more severe disease and a higher mortality rate. Phylogenomic analysis using core genome single-nucleotide polymorphisms showed that RT244 is in the same genetic clade (clade 2) as RT027 but is distinct from all RT027 strains. The pathogenicity locus of the RT244 strain encodes a variant toxin B, and this was confirmed by demonstration of Clostridium sordellii-like cytopathic effect on Vero cells. Toxin B production in culture supernatants was lower than that seen with a RT027 strain. CONCLUSIONS Our findings demonstrate the pathogenic potential of this RT244 C. difficile strain and emphasize the importance of ongoing surveillance for emergent strains.

Rotavirus detection and characterisation in outbreaks of gastroenteritis in aged-care facilities.

BACKGROUND Although rotavirus is a major cause of gastroenteritis in children, its role in adult gastroenteritis and the sensitivity of different methods for its detection in specimens collected from adults are less well understood. OBJECTIVES (1) To examine the frequency and seasonality of rotavirus-associated gastroenteritis outbreaks in aged-care facilities in Victoria, Australia. (2) To determine rotavirus type in these outbreaks. (3) To determine whether other enteropathogenic agents are present in specimens from these outbreaks. (4) To examine the sensitivity of different methods (electron microscopy (EM), reverse transcription-polymerase chain reaction (RT-PCR), enzyme immunoassay (EIA) and latex agglutination (LA)) for the detection of rotavirus in specimens from adults. STUDY DESIGN Specimens from gastroenteritis outbreaks in aged-care facilities forwarded to this laboratory for the years 1997-2000 were tested for enteropathogenic agents by various methods. Epidemiological, clinical and seasonal data from the rotavirus-positive outbreaks were analysed. RESULTS Rotavirus was detected by EM in 18 out of 29 individuals associated with seven out of 53 (13%) gastroenteritis outbreaks in aged-care facilities; norovirus was detected in 22 outbreaks (42%) and astrovirus in one outbreak (2%). No mixed viral infection was found in any outbreak. All rotaviruses were typed as Group A by RT-PCR. The rotaviruses in the seven outbreaks were G-typed as follows: G2 (three outbreaks), G4 (two outbreaks), G1 (one outbreak) and G9 (one outbreak). The rotavirus-associated outbreaks were concentrated in mid-winter to mid-spring. The relative sensitivities of the Group A rotavirus detection methods (for the 29 specimens tested) were EM (18), first-round RT-PCR (11), second-round PCR (19), EIA-visual (19), EIA-photometric (19) and LA (13). CONCLUSIONS In Victoria, Australia, outbreaks of gastroenteritis associated with rotavirus are quite common in aged-care facilities. They involve Group A rotavirus and have a winter/spring seasonality. G-types G1, G2, G4 and G9 were all detected. EIA, second-round PCR and EM proved sensitive methods for rotavirus detection whereas first-round RT-PCR and LA did not.

A Multistate Outbreak of Hepatitis A Associated With Semidried Tomatoes in Australia, 2009

BACKGROUND A large outbreak of hepatitis A affected individuals in several Australian states in 2009, resulting in a 2-fold increase in cases reported to state health departments compared with 2008. Two peaks of infection occurred (April-May and September-November), with surveillance data suggesting locally acquired infections from a widely distributed food product. METHODS Two case-control studies were completed. Intensive product trace-back and food sampling was undertaken. Genotyping was conducted on virus isolates from patient serum and food samples. Control measures included prophylaxis for close contacts, public health warnings, an order by the chief health officer under the Victorian Food Act 1984, and trade-level recalls on implicated batches of semidried tomatoes. RESULTS A multijurisdictional case-control study in April-May found an association between illness and consumption of semidried tomatoes (odds ratio [OR], 3.0; 95% CI 1.4-6.7). A second case-control study conducted in Victoria in October-November also implicated semidried tomatoes as being associated with illness (OR, 10.3; 95% CI, 4.7-22.7). Hepatitis A RNA was detected in 22 samples of semidried tomatoes. Hepatitis A virus genotype IB was identified in 144 of 153 (94%) patients tested from 2009, and partial sequence analysis showed complete identity with an isolate found in a sample of semidried tomatoes. CONCLUSIONS The results of both case-control studies and food testing implicated the novel vehicle of semidried tomatoes as the cause of this hepatitis A outbreak. The outbreak was extensive and sustained despite public health interventions, the design and implementation of which were complicated by limitations in food testing capability and complex supply chains.

Prevalence of antimicrobial-resistant organisms in residential aged care facilities.

Objective: To assess the frequency of, and risk factors for, colonisation with vancomycin‐resistant enterococci (VRE), Clostridium difficile and extended‐spectrum β‐lactamase (ESBL)‐producing organisms in residential aged care facilities (RACFs).

SCYTALIDIUM HYALINUM ISOLATED FROM THE TOE NAIL OF AN AUSTRALIAN PATIENT

The isolation of Scytalidium hyalinum from the toe nail of a patient from Melbourne is reported. This is the first record of the isolation of this fungus from a clinical site in Australia. A brief history is given of the occurrence of Scytalidium hyalinum and the related fungus, Hendersonula toruloidea, in tinea pedis and tinea unguium in immigrants to the United Kingdom from tropical countries. Attention is drawn to the possible presence of these dermatophyte‐like infections in patients in Australia.

Must it have been something I ate

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