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Environmental pathogens, such as Escherichia coli and Streptococcus uberis, are currently the major cause of mastitis within dairy herds. This leads to severe financial losses, lower production rates and deterioration of the general health of the herd. E. coli mastitis is becoming a major threat to high milk-producing dairy herds. This is because of its increasing resistance to antibiotics, rendering antibiotic treatment regimes against E. coli infections mostly ineffective. The aim of this study was to develop a method to select mastitis causing E. coli isolates for the formulation of effective herd specific vaccines. Two methods, namely a genotyping method (Random Amplification of Polymorphic DNA; RAPD) and an antibiogram based method, were used. A dairy farm milking approximately 1000 Holstein cows in the Darling area, Western Cape Province, was selected for this study. The study was conducted over a period of 48 months and mastitis samples were analysed for mastitis pathogens. Antibiogram testing (disk diffusion method) and an in-house developed RAPD analysis method were used to analyse the E. coli isolates. A total of 921 milk samples were analysed from which 181 E. coli isolates were recovered. The number of all other common mastitis pathogens combined was 99 isolates (Streptococcus uberis 18, Streptococcus dysgalactiae 46, Streptococcus agalactiae 1, Staphylococcus epidermidis 21, Arcanobacterium pyogenes 13). All E. coli isolates, except for one, were resistant to at least three antibiotics. Antibiotic variance profiles were also highly erratic. The RAPD analysis revealed high levels of polymorphisms and clear epidemiological trends were observed over time. No similarities in the variance profiles between the antibiotic variance data and phylogenetic data were observed. Formalin inactivated autogenous vaccines were produced containing E. coli isolated from the herd. The vaccines were formulated using the RAPD or antibiogram data of the E. coli isolates. A total of 5 vaccines were formulated using RAPD data (Rvaccines) and one vaccine was formulated using antibiotic variance data (A-vaccine). The RAPD formulated vaccines were more effective than the antibiotic variance formulated vaccine. After each R-vaccination, the number of E. coli mastitis cases declined within the herd. The A-vaccinations seemed to have had no effect, which lead to a rise in E. coli mastitis cases. RAPD analysis on new emerging isolates was able to detect genetic variation from vaccine strains, which in turn facilitated the formulation of new updated vaccines with higher effectiveness than the previous vaccine. Mastitis data prior to and after the vaccination period revealed significant higher incidences of mastitis in the herd than during the vaccination period. This study demonstrated that sufficient sampling practices coupled with a reliable genotyping method, resulted in the formulation of updatable vaccines which were highly effective in controlling E. coli mastitis within the herd. / Thesis (M Environmental Sciences)--North-West University, Potchefstroom Campus, 2012

Objetivo.- Determinar los factores riesgo asociados a Infecciones de vías urinarias por E. coli productoras de Betalactamasas en gestantes. Clínica Good Hope. Durante el periodo Marzo 2014 –2015. Métodos.- Se realizó un estudio observacional, analítico, retrospectivo de casos y controles. Los datos se obtuvieron a partir de la revisión de las historia clínicas de gestantes con IVU en las que cumplieron con el criterio de selección, aplicamos un posteriormente identificamos características sociodemográficas, gineco obstetricas, clínicas de la infección y se analizaron los posibles factores asociados. Para el análisis se elaboró una base de datos obteniendo estadísticas descriptivas; X2 con nivel de significación estadística p<0,05. Resultados.- Se analizaron los datos de 187 pacientes. Se asociaron a E coli BLEE, la anemia, el antecedente de IVU, uso previo antibióticos, inicio de relaciones sexuales tempranas. En el análisis multivariado solo mantuvieron su significancia el uso previo de antibióticos IVU recurrente (IC 95%, OR=2,62), Anemia (IC 95% OR= 28,13), Hipotoroidismo (IC 95%, OR=2,97), (IC 95%, OR= 3,49), la HTA (IC 95%, OR=3,99) y las ITS (IC 95%, OR= 3,29). Así también el 45,5 % fueron casadas, 74,3% tenían estudios superiores. Promedio de edad gestación fue 21,96 semanas. Conclusiones y Recomendaciones.- Se describe la anemia como factor de riesgo para E coli BLEE causante de IVU adquirida en la comunidad, por lo mismo para luchar verdaderamente contra las infecciones urinarias complicadas y sus temibles consecuencias, debemos identificar las características que presenta la población con riesgo de padecerla. Esto justifica el seguimiento de rutina en el control prenatal, tratarla es prevenir las complicaciones.