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    Adhesion of salmonella species and Escherichia coli to collagen fibres of chicken connective tissue : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Science
    (Massey University, 1984) Campbell, Susan
    This thesis describes an investigation of some factors affecting attachment of salmonellae and Escherichia coli to collagen fibres of poultry breast muscle fascie. Direct microscopic techniques were used in conjunction with standard microbiological methods as a means of examining the attachment process. All strains of salmonellae tested, fimbriate Escherichia coli and a strain of Campylobacter coli adhered to collagen when muscle fascie was immersed in water containing cells of the appropriate test culture. Adhesion was dependent on water induced changes in fascie structure and was inhibited or reversed by addition of sodium chloride to the suspending medium. Capsular glycocalyx also prevented attachment of these bacteria to collagen fibres. TEM studies indicated attached cells were held to the collagen by acidic mucopolysaccharides (or glycosaminoglycans) associated with the intercollagen fibre matrix of fascie. Subsequent studies showed hyaluronic acid (a predominant glycosaminoglycan associated with collagenous tissue) could inhibit attachment of selected strains of Salmonella and E. coli, but this ingibition could be reversed by hyaluronidase. Chondroitin-sulphate, a related glycosaminoglycan, only inhibited attachment of E. coli strains. This evidence implicated hyaluronate as a key factor in the attachment process. Since only fimbriate E. coli could bind significant amounts of hyaluronic acid, it is usggested these bacteria may bind directly to tissue glyclsaminoglycans. Salmonellae, however, apparently require an additional bridging compoung (possibly a protein) to mediate adhesion to collagen fibres.
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    Molecular epidemiology of Salmonella typhimurium DT160 in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Veterinary Studies in Public Health at Massey University, Palmerston North, New Zealand
    (Massey University, 2010) Omar, Sharina; Omar, Sharina
    Salmonellosis is a zoonotic bacterial disease of national and international importance. In New Zealand (NZ), the most common foodborne notifiable disease is campylobacteriosis, which is followed by salmonellosis. In 1998, Salmonella enterica subsp. enterica serotype Typhimurium Definitive Type 160 (DT160) was identified in NZ. Since first reported, S. Typhimurium DT160 has caused several epidemics in the country but has not produced significant illness worldwide. Therefore, the objectives of the project were to investigate the molecular epidemiology of S. Typhimurium DT160 and the association between isolates from human and animal origin. Ninety Salmonella isolates obtained in the period between 1999 and 2009 from the Institute of Environmental Science and Research, NZ were assessed for colony morphology, serotype, susceptibility to 11 antimicrobials, virulotyped using Polymerase Chain Reaction (PCR) and the Pulsed Field Gel Electrophoresis (PFGE) patterns were also determined. In addition, 4 isolates were further assessed with Triple Sugar Agar, API20E biochemical and motility tests. All 90 isolates were confirmed as Salmonella spp. with no indications for resistance to multiple antimicrobials. All isolates were susceptible to the antimicrobials used in this study with the exception of 26 and 8 isolates that had intermediate susceptibility against tetracycline and oxytetracycline, respectively. In an attempt to discriminate between potentially pathogenic and pathogenic Salmonella isolates, PCR-based virulotyping was performed based on 12 potential virulence genes. Results revealed that all isolates were positive for at least 10 of the 12 virulence genes. Two of the six isolates negative for one of the virulence genes (invA, iroN, pefA or sifA) were of human origin and the remaining four were sparrow isolates. The PFGE patterns determined with restriction enzymes XbaI and SpeI demonstrated that the genotype profile AA1 accounted for 78/90 (86.7%) of the isolates, whilst the second most common profile, AA2, was found in only three isolates (3.3%), comprising two isolates from sparrows and one from a human. The remaining nine profiles were found in single isolates. All isolates of AA2 profile were PCR negative for sifA. In conclusion, no obvious correlation was observed between the phenol- and geno-type and the isolates, year and month of isolation, and source of the samples. There was no obvious evidence for multidrug resistance among DT160 isolates. The PFGE and virulotyping profiles suggest close relation among majority of isolates with predominant and epidemiologically important genotype persistent in multiple hosts. Finally, the few genotypes with low prevalence in multiple hosts may indicate emergence of sporadic genomic variants in the population.
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    Enhanced surveillance of potentially foodborne enteric disease within a New Zealand public health service : thesis presented in partial fulfilment of the requirements for the degree of Master of Veterinary Studies in Public Health at Massey University, Palmerston North, New Zealand
    (Massey University, 2009) Shadbolt, Tui Louise
    An enhanced notified enteric disease surveillance trial began on 1 July 2007 and continued until 30 June 2008. The aim of the trial was to measure the quality, timeliness and completeness of data collected and submitted by a regional Public Health Service (PHS) to the Institute of Environmental Science and Research Limited (ESR), via the national disease database (EpiSurv) for notified cases of enteric diseases. The trial evaluated two different methods of data collection: postal questionnaires and telephone interviews. Telephone interview techniques were used to improve the contact rate, timeliness and completeness of data gathered from all notified cases of campylobacteriosis in the Manawatu, Horowhenua and Tararua regions. The target set for the project was to achieve a 95% contact rate with 90% full completion of all EpiSurv data fields. For all notified cases of campylobacteriosis a 97% contact rate was achieved in a time frame of between zero to 20 days (three day median) and completeness of all the EpiSurv case report fields ranged between 96 – 100% in the final data. Prior to the commencement of the study, between 1 July 2004 to 30 June 2005, MidCentral PHS (MCPHS) made contact with around 58% of all notified cases of campylobacteriosis and 77% of all other notified enteric disease cases1 . A short pre-screen mail questionnaire, with reply-paid envelope, was sent to all notified cases of cryptosporidiosis, giardiasis, salmonellosis and yersiniosis in the MCPHS regions. EpiSurv case report fields were completed using information supplied in the returned questionnaires. Return rate, timeliness, and completeness were compared with the telephone interview group. Fifty three percent of cases we attempted to contact via mail questionnaire responded within two to 63 days (six day median) and completeness of all the EpiSurv case report fields ranged between 81 – 100%. In addition, we monitored the newly introduced ESR Early Aberration Reporting System (EARS) flags for increased levels of disease compared to historical disease rates, and assessed its usefulness as a tool to identify potential outbreaks in the region. While no outbreaks that had not already been identified by PHS staff were found by monitoring the EARS system, EARS has become an important tool in the MCPHS for comparing our rates of disease with bordering PHSs. EARS also provided a good quick reference tool for media enquiries and the graphs produced in EARS have been well utilised as visual aids for training and seminars presented during the trial period. The results of the surveillance trial initiatives were compared to the rest of New Zealand (NZ) over the same time frame and with a comparable, medium-sized, PHS. While the results of the telephone interviews from the MCPHS trial were close to the comparable PHS, they were significantly higher than for the rest of NZ. The postal questionnaires achieved a lower contact rate than the comparable PHS but similar to the rest of NZ. However, the quality of data gathered in the returned MCPHS postal questionnaire was significantly higher in most fields. Additional analysis was undertaken which indicated that those cases living in higher deprivation and rural areas were less likely to respond to a postal questionnaire. An over-representation of common enteric disease notifications from rural areas in the MCPHS was also highlighted by our research. This trial has shown the effectiveness of utilising telephone interviews and telemarketing techniques for gathering timely and complete data for human enteric disease surveillance within the MCPHS. It has also demonstrated that a short pre-screen questionnaire can be effective in collecting good quality data needed to complete the standard EpiSurv case report form.