Microbiology & Immunology - Research Publications
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ItemNewly Emerging Clones of Bordetella pertussis Carrying prn2 and ptxP3 Alleles Implicated in Australian Pertussis Epidemic in 2008-2010(OXFORD UNIV PRESS INC, 2012-04-15)Australia is experiencing a prolonged epidemic of pertussis that began in 2008. A total of 194 Bordetella pertussis isolates collected from 2008 through 2010 were typed by single-nucleotide polymorphism (SNP) analysis, by multilocus variable number tandem repeats analysis, and by fim3, prn, and ptxP sequence analyses. Strains with 2 closely related SNP profiles carrying prn2 and ptxP3 from the recently emerged SNP cluster I predominated. The data suggest increasing selection among the B. pertussis population in Australia in favor of strains carrying prn2 and ptxP3 under the pressure of acellular vaccine-induced immunity.
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ItemA possible novel Francisella genomic species isolated from blood and urine of a patient with severe illness(ELSEVIER SCI LTD, 2010-07)Two identical isolates were recovered in pure culture from the blood and urine of a patient suffering from severe septicaemia associated with obstructive pyelonephritis secondary to lithotripsy. Preliminary phenotypic and genotypic characterizations based on serological, biochemical and sequence analyses following PCR amplification of selected gene regions indicate that this organism represents a potential new Francisella genomic species.
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ItemHistorical analysis of Salmonella in powdered dairy products in Victoria(DAIRY INDUSTRY ASSOC AUSTRALIA, 2010-08)
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ItemA Multistate Outbreak of Hepatitis A Associated With Semidried Tomatoes in Australia, 2009(OXFORD UNIV PRESS INC, 2012-03-15)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.
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ItemAn outbreak of Salmonella Infantis gastroenteritis in a residential aged care facility associated with thickened fluids(CAMBRIDGE UNIV PRESS, 2012-12)Twenty-two confirmed cases of Salmonella Infantis were identified in 70 residents of high-level care areas of a residential aged care facility in Sydney in April 2010 during an outbreak of gastroenteritis. A retrospective cohort study was conducted to identify a possible cause. Consuming a soft diet, puréed diet, or thickened fluid were each independently associated with illness. A logistic regression showed consumption of thickened fluid to be the only significant exposure associated with illness (adjusted odds ratio 11·8, 95% confidence interval 1·9-75·9). It was postulated that the thickened fluid had been contaminated by chicken mince, a sample of which also cultured S. Infantis. This finding reinforces the need to educate food-handlers on the risk of potential cross-contamination; it also highlights the need to consider all dietary components, such as thickened fluids, as potential vehicles for transmission in an outbreak.
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ItemSalmonella Rubislaw gastroenteritis linked to a pet lizard(WILEY, 2010-07-05)
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ItemEmergence and evolution of multiply antibiotic-resistant Salmonella enterica serovar Paratyphi B D-tartrate-utilizing strains containing SGI1.(American Society for Microbiology, 2009-06)The first Australian isolate of Salmonella enterica serovar Paratyphi B D-tartrate-utilizing (dT(+)) that is resistant to ampicillin, chloramphenicol, florfenicol, streptomycin, spectinomycin, sulfonamides, and tetracycline (ApCmFlSmSpSuTc) and contains SGI1 was isolated from a patient with gastroenteritis in early 1995. This is the earliest reported isolation globally. The incidence of infections caused by these SGI1-containing multiply antibiotic-resistant S. enterica serovar Paratyphi B dT(+) strains increased during the next few years and occurred sporadically in all states of Australia. Several molecular criteria were used to show that the early isolates are very closely related to one another and to strains isolated during the following few years and in 2000 and 2003 from home aquariums and their owners. Early isolates from travelers returning from Indonesia shared the same features. Thus, they appear to represent a true clone arising from a single cell that acquired SGI1. Some minor differences in the resistance profiles and molecular profiles also were observed, indicating the ongoing evolution of the clone, and phage type differences were common, indicating that this is not a useful epidemiological marker over time. Three isolates from 1995, 1998, and 1999 contained a complete sul1 gene but were susceptible to sulfamethoxazole due to a point mutation that creates a premature termination codon. This SGI1 type was designated SGI1-R. The loss of resistance genes also was examined. When strains were grown for many generations in the absence of antibiotic selection, the loss of SGI1 was not detected. However, variants SGI1-C (resistance profile SmSpSu) and SGI1-B (resistant to ApSu), which had lost part of the integron, arose spontaneously, presumably via homologous recombination between duplications in the In104 complex integron.