[No abstract submitted] / Science, Faculty of / Microbiology and Immunology, Department of / Graduate

Orientador : Fumio Yokoya / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-07-16T18:11:26Z (GMT). No. of bitstreams: 1 Schocken-Iturrino_RubenPablo_D.pdf: 2947673 bytes, checksum: 439053c852613fdb9ecfc690aced4dd5 (MD5) Previous issue date: 1980 / Resumo: O presente trabalho teve por finalidade detectar a presença de Clostridium botulinum em produtos cárneos embalados a vácuo e testar mediante inoculação experimental se os produtos analisados permitiriam ou não o desenvolvimento de C.botulinum e a produção de sua toxina. Os testes empregados demonstraram a ausência de C.botulinum, porem foi detectada a presença de Clostridium tetani em dezessete amostras. Na inoculação experimental os resultados demonstraram que o C. botulinum cresceu em quase todas as amostras armazenadas a temperaturas acima de 3°C. Também foi demonstrado que os teores de cloreto de sódio, nitrito e nitrato determinados nas amostras, não inibem a germinação de esporos de Clostridium botulinum e sim as baixas temperaturas / Abstract: The present work has as its objective the detection of Clostridium botulinum in vaccum-packed meat products and to test experimentally if these kinds of products will suport or not the development of C.botulinum and the production of its toxins. The tests used, showed the absence of C.botulinum, however the presence of Clostridium tetani was detected in seventeen samples. In the experimental inhicuiaLi on the results demonstrated that C. botulinum grew in almost all the samples stored at temperatures above 3°C. Also, it was proved that the concentrations of sodium chloride, nitrite and nitrate detected in the samples, was not sufficient to inhibit the germination of Clostridium botulinum spores. Rather, this was accomplished by the storage at low temperatures / Doutorado / Doutor em Engenharia de Alimentos

1 Microbiology Laboratory, Charlotte Maxeke Johannesburg Academic Hospital, Department of Clinical Microbiology and Infectious Diseases, National Health Laboratory Service and University of the Witwatersrand, Johannesburg / Background: Clostridium difficile is a common cause of healthcare-associated diarrhoea. Laboratory testing for C. difficile infection (CDI) remains an area of confusion as there is not a single accepted reference standard or a single best test. Aim: To analyse the impact of different diagnostic methods on reported CDI rates. In addition, CDI incidence rates at Charlotte Maxeke Johannesburg Academic Hospital (CMJAH) were determined. Method: Results of stool samples submitted for C. difficile testing at CMJAH from 1 January 2014 to 31 August 2017 were reviewed. From January 2014 to July 2016, samples were tested by polymerase chain reaction (PCR) or toxin immunoassay, and from August 2016 to August 2017 algorithm-based testing (glutamate dehydrogenase and toxin immunoassay followed by PCR) was performed. Results: A total of 4829 samples were submitted. For the first period, toxin immunoassay and PCR showed a positivity rate of 11.4% and 21.1%, respectively, with an overall positivity rate of 18.7% (95% CI: 15.6 – 21.9). For the second period, the positivity rate was 15.9% (95% CI: 11.3 – 17.7). This rate included samples that were GDH positive and either showed toxin production or had a positive Xpert® result. CDI incidence for the two periods was different, with an incidence rate of 8.8 and 6.1 per 10 000 patient-days for the first and second periods, respectively. Conclusion: The choice of laboratory testing method has a major impact on the diagnosis of CDI, and therefore on the reported rates of CDI. Standardisation of laboratory testing and incidence rate reporting is required in order to obtain robust and reliable data. / E.K. 2019

Abstract not available

Thesis (Ph.D.)--University of Western Australia, 2003.

Indiana University-Purdue University Indianapolis (IUPUI) / Clostridium perfringens is an important human pathogen known to cause a range of diseases including diarrhea, necrotizing bowel disease and gas gangrene. Though potentially pathogenic, this microorganism is commonly identified in the fecal microbiota of healthy individuals. The major clinical findings associated with C. perfringens diseases are linked to production of potent toxins. In 1997, Gibert et al. identified a new toxin, the beta2 toxin, from a C. perfringens strain from a piglet with necrotic enteritis. Subsequently, this new beta2 toxin gene (cpb2) has been identified in C. perfringens from dogs, horses, and other animals. The principal objective of this investigation was to study cpb2 and the beta2 toxin in C. perfringens isolates from human sources. The C. perfringens isolates were grouped into three different populations: 1) fecal samples from patients suspected of having C. perfringens gastrointestinal illnesses (e.g. antibiotic-associated diarrhea or colitis), 2) extraintestinal specimen sources (e.g. wounds, abscesses, blood cultures), 3) a control group of isolates from healthy volunteers. Results of studies using different PCR methods and nucleotide sequencing revealed that cpb2 was present in the genome of isolates from all populations, and that the genetic variation between cpb2 from the different C. perfringens isolates was greater then expected. Using western blotting techniques, it was found that the beta2 protein was not expressed by all cpb2 positive C. perfringens isolates. Finally, different variants of cpb2 were cloned into E. coli, and the recombinant beta2 protein used in cell cytotoxicity assays. Results from these assays demonstrated that recombinant beta2 proteins caused a range of cellular damage at different levels of protein concentration and different lengths of time. Our results from these experiments provided new information regarding cpb2 in C. perfringens isolates from human sources; as well as on the range of variation of cpb2 genes, differences in beta2 toxin expression, and differences in the effects of recombinant beta2 toxin on enterocytes. This information could help to explain differences in virulence between C. perfringens isolates, differences in diseases and disease severity.

The main purpose of this study was to assess outcomes (i.e., inpatient mortality, transplant failure or rejection, colectomy, and hospital length of stay) of clostridium difficile infection (CDI) and the association of expenditures (i.e., charges and costs) and CDI in pediatric solid organ transplant (SOT) recipients. Data from the 2000, 2003, 2006, and 2009 Kids’ Inpatient Database (KID) files were used to identify events with SOT- related ICD-9-CM diagnosis codes. Logistic regression was used to assess the association of CDI and dichotomous outcome variables, while log-linked gamma regression models were used to assess the association of CDI and continuous outcome variables. Methods accounting for the complex survey sample design of the KID were used when performing all statistical analyses. The total number of pediatric SOT hospital events was 48,286. The overall prevalence of CDI for pediatric SOT hospitalizations was 1.76%. For SOT hospitalizations with CDI, inpatient mortality was 1.63%; the prevalence of transplant failure or rejection events was 27.71%; the prevalence of a colectomy was 4.86%. The median hospital length of stay was seven days; the median charge and cost for each hospitalization was $48,409 and $17,412, respectively. The results showed that CDI was not significantly associated with inpatient mortality or transplant failure/ rejection in pediatric SOT hospitalizations. SOT patients with CDI were 2.6 times more likely to have a colectomy than SOT patient without CDI. The mean hospital length of stay (LOS) for a SOT admission with CDI was approximately 2 times the mean LOS for a SOT admission without CDI. The mean charges and the mean costs for a SOT admission with CDI was approximately 2 times that for a SOT admission without CDI. In conclusion, CDI diagnoses were not significantly associated with higher inpatient mortality or transplant failure/ rejection for pediatric SOT hospitalizations. But CDI was significantly associated with a higher prevalence of a colectomy, longer hospital LOS, higher charges, and higher costs (all p<0.05). To avoid substantially higher expenditures and health care utilization, CDI in pediatric SOT recipients should be prevented when possible and promptly diagnosed and treated when it occurs. / text

Clostridium difficile infection (CDI) has recently emerged as a major health problem. An understanding of the micro-epidemiology of the infection is decisive for the design and implementation of control polices. Presently, typing using PCR ribotyping (RT), Multi-locus Sequence Typing (MLST) and Multi-locus Variable Number Tandem Repeat Analysis (MLVA) can be used to investigate recent transmission events of C. difficile. In the case of MLVA, different criteria have been used to classify strains and this reflects inconsistencies in the contemporary knowledge of change in MLVA polymorphisms. In this study, temporal and spatial investigations were conducted to better understand the dynamics of change in C. difficile VNTR loci. The 164 isolates from the collection yielded 25 different STs, with ST161 and ST171 being newly described. The congruence of MLST to the other typing methods of RT and tcdC, strengthens the robustness of discrimination of these methods. Sub-typing using MLVA, however yielded 139 strains, and again there was congruence to the aforementioned methods. Clustering of MLVA strains into groups revealed Single and Multi-Isolate Strains linked together as single locus variants with groups coordinating with MLST types within ST1 and ST3. The lowest MLVA diversity was seen in the Period of Increased Incidence and was primarily responsible for high incidence rates. These groups of MLVA related isolates were used to characterise the instability of the repeat sequences of MLVA loci. 2 Locus differences were examined from the perspective of the genetic role of the locus, DNA polymerase amplification, the impact of different growth conditions on the fitness of the repeat sequences and of the frequency of repeat changes in the natural population. These studies have focused on the on the drivers of change of VNTR loci in general and will allow a more rational approach to using MLVA loci in epidemiological studies.

No description available.

Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 109-118). Also available on the World Wide Web.