ETD Collection

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    Molecular characterization of multidrug-resistant Salmonella Isangi in hospitalized patients
    (2008-08-19T09:22:39Z) Kruger, Tersia
    ABSTRACT Extended-spectrum beta-lactamase (ESBL)-producing Salmonella enterica serotype Isangi has emerged as a common Salmonella serotype affecting mainly children in hospitals throughout South Africa. Between 2000 and 2002, 279 S. Isangi isolates from single infection episodes were referred from 21 hospitals in 5 provinces to the Enteric Diseases Reference Unit of the National Institute for Communicable Diseases of South Africa. All isolates were subjected to antibiotic susceptibility testing and three disk-diffusion methods confirmed ESBL-production in 273 isolates. PCR and nucleotide sequencing of 101 isolates identified TEM-1 (2%), TEM-63 (91%), a novel TEM-131 (7%), and SHV-5 (2%), but CTX-M was not found. Plasmid profiling produced types with 1 to 6 plasmids, 7.4kb to 166kb in size, which were neither serotype nor ESBL-type specific. Pulsed-field gel electrophoresis revealed four major clusters while sub-clusters with identical, or near identical banding patterns suggested extensive intra-hospital transmission and clonal spread between hospitals and provinces in South Africa.
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    Analysis of the Genetic Diversity of Neisseria Meningitidis in South Africa
    (2006-11-15T07:58:01Z) Coulson, Garry Brian
    Meningococcal disease is an important cause of morbidity and mortality worldwide, particularly in children and young adults. Epidemics caused by Neisseria meningitidis continue to plague many countries on a global scale, none more so than countries of the African ‘meningitis belt’, where attack rates can reach up to 1000/100,000 population. It has been well recognized that most epidemic and endemic cases of meningococcal disease are caused by a limited number of genetically defined clonal groups. The objective of this molecular epidemiological study was to genotypically characterize strains of N. meningitidis collected in South Africa from July 1999 to July 2002. Characterization of meningococcal strains belonging to serogroup A, B, C, W135 and Y, by PFGE and MLST allowed us to determine the genetic population structure of N. meningitidis in South Africa, and thus identify the predominant clonal groups responsible for the majority of meningococcal disease in the country over this period. The results from the genotypic characterization revealed that the greatest majority of meningococcal disease in South Africa was caused by a strains belonging to only a few “hyperinvasive lineages”, most notably strains of the ST-44 complex (lineage III), ST-32 complex (ET-5 complex), ST-11 complex (ET-37 complex), and the ST-1 complex (subgroup I/II) which have all been responsible for major epidemics worldwide. These findings have direct implications on public health decision, particularly with regards to the development of effective intervention and control strategies, and emphasize the need for continuous long-term monitoring of the circulation of these strains in the population.