Browsing by Author "Nakavuma, Jessica L."
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Item Comparison of transformation frequencies among selected Streptococcus pneumoniae serotypes(International journal of antimicrobial agents, 2010) Joloba, Moses L.; Kidenya, Benson R.; Kateete, David P.; Katabazi, Fred A.; Muwanguzi, Julian K.; Asiimwe, Benon B.; Alarakol, Simon P.; Nakavuma, Jessica L.; Bajaksouzian, Saralee; Windau, Anne; Jacobs, Michael R.Although there are over 90 serotypes of Streptococcus pneumoniae, antimicrobial resistance is predominantly found in a limited number of serotypes/serogroups, namely 6, 9, 14, 19 and 23. There is no compelling mechanism to account for this restriction. We aimed to determine whether serotypes commonly associated with drug resistance have higher transformation frequencies than those that are susceptible to antimicrobial agents. An in vitro investigation of the genetic transformation frequency of drug-resistant serotypes compared with that of susceptible serotypes under the influence of synthetic competence-stimulating peptides was performed. The transforming DNA was genomic DNA carrying a Tn916-like transposon containing the mefE gene that confers resistance to erythromycin. It was observed that serotypes 6, 9, 14, 19 and 23, which are highly associated with drug resistance, do not exhibit a higher degree of transformation efficiency than other serotypes. These findings suggest that the association of serotype with drug resistance is likely due to prolonged exposure to transforming DNA resulting from longer nasopharyngeal carriage and to a greater selective pressure from antimicrobials, particularly in children. This is the first study to compare the transformation frequencies of pneumococcal clinical isolates using genomic DNA that carries the composite Tn916-like element.Item Disparate thermostability profiles and HN gene domains of field isolates of Newcastle disease virus from live bird markets and waterfowl in Uganda(Virology Journal, 2016) Omony, John B.; Wanyana, Agnes; Mugimba, Kizito K.; Kirunda, Halid; Nakavuma, Jessica L.; Otim-Onapa, Maxwell; Byarugaba, Denis K.Uganda poultry production is still faced with frequent outbreaks of Newcastle disease (ND) in the backyard free-range systems despite the accessibility of cross protective vaccines. Live bird markets and waterfowl has long been reported as a major source of disease spread as well as potential sources of avirulent strains that may mutate to virulent strains. ND-virus has been reported enzootic in Ugandan poultry but limited studies have been conducted to ascertain thermostability phenotypes of the Ugandan ND-virus strains and to understand how these relate to vaccine strains. Methods: This study evaluated thermostability of 168 ND-virus field isolates recovered from live bird markets and waterfowls in Uganda compared to two live commercial vaccine strains (I2 and LaSota) by standard thermostability procedures and Hemagglutinin-Neuraminidase (HN) gene domains. The known pathotypes with thermostability profiles were compared at HN amino acid sequences. Results: Field isolates displayed disparate heat stability and HN gene domains. Thermolabile isolates were inactivated within 15 min, while the most thermostable isolates were inactivated in 120 min. Four thermostable isolates had more than 2 log2 heamaglutinin (HA) titers during heat treatment and the infectivity of 9.8 geometric mean of log10 EID50 % in embryonated eggs. One isolate from this study exhibited a comparable thermostability and stable infectivity titers after serial passages, to that of reference commercial vaccine was recommended for immunogenicity and protection studies. Conclusion: The occurrence of ND-virus strains in waterfowl and live bird markets with disparate thermostability and varying HN gene domains indicate circulation of different thermostable and thermolabile ND-virus pathotypes in the country.Item High pathogenicity and low genetic evolution of avian paramyxovirus type I (Newcastle disease virus) isolated from live bird markets in Uganda(Virology Journal, 2014) Byarugaba, Denis K.; Mugimba, Kizito K.; Omony, John B.; Okitwi, Martin; Wanyana, Agnes; Otim, Maxwell O.; Kirunda, Halid; Nakavuma, Jessica L.; Teillaud, Angélique; Paul, Mathilde C.; Ducatez, Mariette F.Newcastle disease is still a serious disease of poultry especially in backyard free-range production systems despite the availability of cross protective vaccines. Healthy-looking poultry from live bird markets have been suspected as a major source of disease spread although limited studies have been conducted to ascertain the presence of the virulent strains in the markets and to understand how they are related to outbreak strains. Methods: This study evaluated the occurrence of Newcastle disease virus in samples collected from poultry in live bird markets across Uganda. The isolates were pathoyped using standard methods (mean death time (MDT), intracelebral pathogenicity index (ICPI), and sequencing of the fusion protein cleavage site motif) and also phylogenetically analysed after sequencing of the full fusion and hemagglutin-neuraminidase genes. The isolates were classified into genotypes and subgenotypes based on the full fusion protein gene classification system and compared with other strains in the region and world-wide. Results: Virulent avian paramyxovirus type I (APMV-1) (Newcastle disease virus) was isolated in healthy-looking poultry in live bird markets. The viruses belonged to a new subgenotype, Vd, in genotype V, and clustered together with Tanzania and Kenya strains. They harbored low genetic diversity. Conclusion: The occurrence of virulent AMPV-1 strains in live bird markets may serve as sources of Newcastle disease outbreaks in non-commercial farmsItem In vitro Antibacterial Activity of Ocimum suave Essential Oils against Uropathogens Isolated from Patients in Selected Hospitals in Bushenyi District, Uganda(British Microbiology Research Journal, 2015) Tibyangye, Julius; Okech, Matilda A.; Nyabayo, Josephat M.; Nakavuma, Jessica L.Aims—To determine antibacterial activity of Ocimum suave essential oils against bacterial uropathogens. Study Design—A cross sectional and experimental study. Place and Duration of Study—Six selected hospitals in Bushenyi District, Uganda between June 2012 and July 2013. Methodology—Clean catch midstream urine samples were collected and inoculated on Cystine Lysine Electrolyte Deficient (CLED) agar. The plates were incubated at 37°C for 24hrs to 48hrs. The O. suave essential oils were extracted by hydrodistillation of leaves for 4hrs using a Clevenger apparatus. The oil was collected and dried over anhydrous sodium sulphate (Na2SO4) and kept at 4°C till further use. The antimicrobial activity of O. suave essential oils against isolates was determined by agar well method. The MIC of O. suave essential oil extract was carried out by microbroth dilution method. Results—Of the three hundred (300) midstream urine samples collected, 67(22.33%) had significant bacterial growth. Escherichia coli is the most common isolate (61.19%, n = 41).Item Microbiological Quality of Traditionally Smoked Fish from Lake Victoria Crescent, Uganda(Food Science and Quality Management, 2021) Abigaba, Rubaijaniza; Nakavuma, Jessica L.; Kankya, Clovice; Kabasa, John D.Microbiological quality of traditionally smoked fish was assessed to ascertain the effectiveness of traditional smoking process and handling conditions for smoked fish shelf-life and safety. Fish smoking is a popular preservation method in Uganda. Although fish smoking is a widely used method of preservation, the presence of spoilage and pathogenic bacteria in smoked fish and food borne illnesses remain a threat in developing countries. However, little is known about microbial quality of fish smoked from Uganda. In light of this, the status of spoilage, hygiene and pathogenic indicator organisms in fish (Nile perch) was investigated. A total of 75 randomly selected fresh, freshly smoked, and on shelf smoked fish from landing sites and markets respectively, were obtained for microbial and moisture content analysis. Descriptive statistics was used to present the data, while ANOVA and Tukey tests were used to analyze the data. The study revealed that, the smoking process significantly (P<0.05) reduced microbial load in freshly fish to levels acceptable for consumption, despite the high levels of moisture content in the range of 59.2% to 66.5%. The mean microbial load (log of cfu/g) of indicator organisms for samples from different sites varied from; 9.97 to 10.18; 7.39 to 8.19 (aerobic mesophilic bacteria or TPC), 5.18 to 5.27; 0 to 4.28 (total coliforms), 2.73 to 5.55; 0 to 0.85 (E. coli), 4.97 to 7.32; 0 to 3.11 (S. aureus), and 2.21 to 4.56; 0 to 0.82 (Yeasts and molds), for fresh and smoked fish samples respectively. Additionally, mean microbial load for on shelf smoked fish from markets varied from; 8.2 to 10.57 (TPC), 2.8-6.63 (total coliforms), 0 to 6.11 (E. coli), 6.74 to 8.89 (S. aureus), and 0 to 5.51 (Yeasts and molds). Although findings showed that, traditional fish smoking was somewhat effective in reducing microbial load to acceptable levels, the microbial status of on shelf smoked fish indicated poor fish handling and storage. Therefore, proper fish handling during and post-smoking as well as cooking before consumption, are highly recommended for assured shelf-life and safety of smoked fish for consumption in Uganda.