Browsing by Author "Katabazi, Fred A."

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    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.
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    Evaluation of in-house PCR for diagnosis of smear-negative pulmonary tuberculosis in Kampala, Uganda
    (BMC Research Notes, 2012) Nakiyingi, Lydia; Kateete, David P.; Ocama, Ponsiano; Worodria, William; Sempa, Joseph B.; Asiimwe, Benon B.; Katabazi, Fred A.; Katamba, Achilles; Huang, Laurence; Joloba, Moses L.; Mayanja-Kizza, Harriet
    Nucleic acid amplification tests (NAATs) have offered hope for rapid diagnosis of tuberculosis (TB). However, their efficiency with smear-negative samples has not been widely studied in low income settings. Here, we evaluated in-house PCR assay for diagnosis of smear-negative TB using Lowenstein-Jensen (LJ) culture as the baseline test. Two hundred and five pulmonary TB (PTB) suspects with smear-negative sputum samples, admitted on a short stay emergency ward at Mulago Hospital in Kampala, Uganda, were enrolled. Two smear-negative sputum samples were obtained from each PTB suspect and processed simultaneously for identification of MTBC using in-house PCR and LJ culture. Results: Seventy two PTB suspects (35%, 72/205) were LJ culture positive while 128 (62.4%, 128/205) were PCR-positive. The sensitivity and specificity of in-house PCR for diagnosis of smear-negative PTB were 75% (95% CI 62.6-85.0) and 35.9% (95% CI 27.2-45.3), respectively. The positive and negative predictive values were 39% (95% CI 30.4-48.2) and 72.4% (95% CI 59.1-83.3), respectively, while the positive and negative likelihood ratios were 1.17 (95% CI 0.96-1.42) and 0.70 (95% CI 0.43-1.14), respectively. One hundred and seventeen LJ culturenegative suspects (75 PCR-positive and 42 PCR-negative) were enrolled for follow-up at 2 months. Of the PCR-positive suspects, 45 (60%, 45/75) were still alive, of whom 29 (64.4%, 29/45) returned for the follow-up visit; 15 (20%, 15/75) suspects died while another 15 (20%, 15/75) were lost to follow-up. Of the 42 PCR-negative suspects, 22 (52.4%, 22/42) were still alive, of whom 16 (72.7%, 16/22) returned for follow-up; 11 (26.2%, 11/42) died while nine (21.4%, 9/42) were lost to follow-up. Overall, more PCR-positive suspects were diagnosed with PTB during follow-up visits but the difference was not statistically significant (27.6%, 8/29 vs. 25%, 4/16, p = 0.9239). Furthermore, mortality was higher for the PCR-negative suspects but the difference was also not statistically significant (26.2% vs. 20% p = 0.7094). Conclusion: In-house PCR correlates poorly with LJ culture for diagnosis of smear-negative PTB. Therefore, in-house PCR may not be adopted as an alternative to LJ culture.
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    Identification of Staphylococcus aureus: DNase and Mannitol salt agar improve the efficiency of the tube coagulase test
    (Annals of clinical microbiology and antimicrobials, 2010) Kateete, David P.; Kimani, Cyrus N.; Katabazi, Fred A.; Okeng, Alfred; Okee, Moses S.; Nanteza, Ann; Joloba, Moses L.; Najjuka, Florence C.
    The ideal identification of Staphylococcus aureus clinical isolates requires a battery of tests and this is costly in resource limited settings. In many developing countries, the tube coagulase test is usually confirmatory for S. aureus and is routinely done using either human or sheep plasma. This study evaluated Mannitol salt agar and the deoxyribonuclease (DNase) test for improving the efficiency of the tube coagulase test in resource limited settings. The efficiency of human and sheep plasma with tube coagulase tests was also evaluated.
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    Pertussis Prevalence and Its Determinants among Children with Persistent Cough in Urban Uganda
    (PLoS ONE, 2015) Kayina, Vincent; Kyobe, Samuel; Katabazi, Fred A.; Kigozi, Edgar; Okee, Moses; Odongkara, Beatrice; Babikako, Harriet M.; Whalen, Christopher C.; Joloba, Moses L.; Musoke, Philippa M.; Mupere, Ezekiel
    We determined prevalence of pertussis infection and its associated host and environmental factors to generate information that would guide strategies for disease control. Methods In a cross-sectional study, 449 children aged 3 months to 12 years with persistent cough lasting 14 days were enrolled and evaluated for pertussis using DNA polymerase chain reaction (PCR) and ELISA serology tests. Results Pertussis prevalence was 67 (15% (95% Confidence Interval (CI): 12–18)) and 81 (20% (95% CI: 16–24)) by PCR and ELISA, respectively among 449 participating children. The prevalence was highest in children with >59 months of age despite high vaccination coverage of 94% in this age group. Study demographic and clinical characteristics were similar between pertussis and non-pertussis cases. Of the 449 children, 133 (30%) had a coughing household member and 316 (70%) did not. Among 133 children that had a coughing household member, sex of child, sharing bed with a coughing household member and having a coughing individual in the neighborhood were factors associated with pertussis. Children that had shared a bed with a coughing household individual had seven-fold likelihood of having pertussis compared to children that did not (odds ratio (OR) 7.16 (95% CI: 1.24– 41.44)). Among the 316 children that did not have a coughing household member, age <23 months, having or contact with a coughing individual in neighborhood, a residence with one room, and having a caretaker with >40 years of age were the factors associated with pertussis. Age <23months was three times more likely to be associated with pertussis compared to age 24–59 months (OR 2.97 (95% CI: 1.07–8.28)). Conclusion Findings suggest high prevalence of pertussis among children with persistent cough at a health facility and it was marked in children >59 months of age, suggesting the possibility of waning immunity. The factors associated with pertussis varied by presence or absence of a coughing household member.
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    Prevalence of Virulence Determinants in Staphylococcus Epidermidis from ICU Patients in Kampala, Uganda
    (The Journal of Infection in Developing Countries, 2012) Okee, Moses S.; Joloba, Moses L.; Okello, Margaret; Najjuka, Florence C.; Katabazi, Fred A.; Bwanga, Freddie; Nanteza, Ann; Kateete, David P.
    Staphylococcus epidermidis is often considered a non-pathogenic organism but it causes nosocomial infections. To distinguish invasive strains, comparative studies of patient and community isolates may offer some clues. We investigated the distribution of virulence determinants in patient isolates from Uganda. S. epidermidis isolates were identified with the Staph API ID 32 kit. Antimicrobial susceptibility, biofilm formation and hemolysis were detected with standard procedures. Genes associated with virulence (aap, atlE, bhp, hla, hld, ica, IS256, sdrE, sea, tsst) and antimicrobial resistance (aac(6')-Ie-aph(2'')-Ia, aph(3')-IIIa, ant(4')-Ia, blaZ, mecA, vanA/vanB1) were detected by PCR. S. epidermidis grew in 30 (30/50, 60%) ICU samples and 20 (20/60, 33%) community samples (one isolate per sample per patient/person). All ICU isolates (30/30, 100%) were IS256 and hld positive, 22 (22/30, 73%) were biofilm/ica positive, 21 (21/30, 70%) were hemolytic on blood agar, nine (9/30, 30%) contained atlE gene, six (6/30, 20%) hla gene, five (5/30, 17%) aap gene, and three (3/30, 10%) bhp gene. A gene encoding an aminoglycoside-modifying enzyme, aph(3')-IIIa, was highly prevalent (28/30, 93%), while blaZ (2/30, 7%), mecA (3/30, 10%), vanA (3/30, 10%) and vanB1 (3/30, 10%) were less prevalent. Of the community isolates, one (1/20, 5%) was ica positive, two (2/20, 10%) formed biofilms, and three (3/20, 15%) possessed the atlE gene. bhp, aap, IS256, hld and antimicrobial resistance genes were not detected in community isolates. S. epidermidis from ICU patients in Mulago Hospital is potentially virulent and could be a reservoir for antimicrobial resistant genes.