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 ß-lactamase (ESBL)-producing organisms in residential aged care facilities (RACFs). DESIGN, SETTING AND PARTICIPANTS: We conducted a point prevalence survey in October-November 2010 in three RACFs associated with our health service. A single faecal sample was collected from each participating resident and screened for the presence of VRE, C. difficile and ESBL-producing organisms. Presence of risk factors for antibiotic-resistant organisms was identified using a questionnaire. MAIN OUTCOME MEASURES: Prevalence of colonisation with VRE, C. difficile and ESBL-producing organisms; molecular typing of ESBL-producing organisms; prevalence of risk factors including presence of a urinary catheter, recent inpatient stay in an acute care setting and recent antibiotic consumption. RESULTS: Of 164 residents in the three facilities, 119 (73%) were screened. Mean age of screened residents was 79.2 years, and 61% were women; 74% had resided in the RACF for > 12 months, 21% had been given antibiotics within the past month and 12% had been in an acute care centre within the past 3 months. Overall rates of VRE (2%) and C. difficile (1%) colonisation were low, but ESBL-producing Escherichia coli was detected in 14 residents (12%) overall, with half of these residing in one wing of an RACF (27% of wing residents tested). Ten of the 14 ESBL-producing isolates had identical molecular typing patterns and belonged to genotye CTX-M-9. Eight of 13 residents had persistent colonisation on repeat testing 3 months later. CONCLUSION: We found a high prevalence of multiresistant ESBL-producing E. coli in RACF residents. A clonal relatedness of isolates suggests possible transmission within the facility. RACFs should have programs emphasising processes that will limit spread of these organisms, namely good hand hygiene compliance, enhanced environmental cleaning and dedicated antimicrobial stewardship programs.

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.