Browsing by Author "Kaonga P"

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Microbiologic and virulence characteristics of Moraxella catarrhalis isolates from Zambian children presenting with acute pneumonia.
(2022-Dec) Nawa M; Mwansa J; Mwaba J; Kaonga P; Mukubesa AN; Simuyandi M; Chisenga CC; Alabi P; Mwananyanda L; Thea DM; Chilengi R; Kwenda G; Department of Postgraduate Studies and Research, School of Medicine, Lusaka Apex Medical University, Lusaka, Zambia.; Department of Global Health, Boston University School of Public Health, Boston, Massachusetts, USA.; Department of Biomedical Sciences, School of Health Sciences, University of Zambia, Lusaka, Zambia.; Department of Disease Control, School of Veterinary Medicine, University of Zambia, Lusaka, Zambia.; Centre for Infectious Disease Research in Zambia, Lusaka, Zambia.; Department of Internal Medicine, School of Medicine, University of Zambia, Lusaka, Zambia.; CIDRZ; Centre for Infectious Disease Research in Zambia (CIDRZ)
BACKGROUND: Moraxella catarrhalis is one of the bacterial pathogens associated with childhood pneumonia, but its clinical importance is not clearly defined. OBJECTIVE: This study aimed to investigate the microbiologic and virulence characteristics of M. catarrhalis isolates obtained from children with pneumonia in Lusaka, Zambia. METHODS: This retrospective, cross-sectional study analyzed 91 M. catarrhalis isolates from induced sputum samples of children less than 5 years of age with pneumonia enrolled in the Pneumonia Etiology Research for Child Health study in Lusaka, Zambia between 2011 and 2014. Bacteria identification and virulence genes detection were performed by PCR and DNA sequencing, while antimicrobial susceptibility testing was determined by the Kirby-Bauer method. RESULTS: All the M. catarrhalis isolates were obtained from good-quality sputum samples and were the predominant bacteria. These isolates harbored virulence genes copB (100%), ompE (69.2%), ompCD (71.4%), uspA1 (92.3%), and uspA2 (69.2%) and were all β-lactamase producers. They showed resistance to ampicillin (100%), amoxicillin (100%), trimethoprim-sulfamethoxazole (92.3%), ciprofloxacin (46.2%), chloramphenicol (45.1%), erythromycin (36.3%), tetracycline (25.3%), cefuroxime (11.0%), and amoxicillin-clavulanate (2.2%), with 71.4% displaying multi-drug resistant phenotype but all susceptible to imipenem (100%). CONCLUSION: This study showed that M. catarrhalis isolates were the predominant or only bacterial isolates from the sputum samples analyzed. The findings provide supportive evidence for the pathogenic potential role of this bacterium in pediatric pneumonia. High multidrug resistance was also observed amongst the isolates, which can result in affected patients not responding to standard treatment, leading to prolonged illness, increased healthcare costs, and risk of death.
Rifaximin Reduces Markers of Inflammation and Bacterial 16S rRNA in Zambian Adults with Hepatosplenic Schistosomiasis: A Randomized Control Trial.
(2018-Apr) Sinkala E; Zyambo K; Besa E; Kaonga P; Nsokolo B; Kayamba V; Vinikoor M; Zulu R; Bwalya M; Foster GR; Kelly P; Paediatric Centre of Excellence Laboratory, University Teaching Hospital, Lusaka, Zambia.; Department of Internal Medicine, Tropical Gastroenterology & Nutritional Group, University of Zambia, Lusaka, Zambia.; Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama.; Blizard Institute, Barts & The London School of Medicine, Queen Mary University of London, London, United Kingdom.; Department of Internal Medicine, University Teaching Hospital, Lusaka, Zambia.; Centre for Infectious Disease Research in Zambia, Lusaka, Zambia.; CIDRZ; Centre for Infectious Disease Research in Zambia (CIDRZ)
Cirrhosis is the dominant cause of portal hypertension globally but may be overshadowed by hepatosplenic schistosomiasis (HSS) in the tropics. In Zambia, schistosomiasis seroprevalence can reach 88% in endemic areas. Bacterial translocation (BT) drives portal hypertension in cirrhosis contributing to mortality but remains unexplored in HSS. Rifaximin, a non-absorbable antibiotic may reduce BT. We aimed to explore the influence of rifaximin on BT, inflammation, and fibrosis in HSS. In this phase II open-label trial (ISRCTN67590499), 186 patients with HSS in Zambia were evaluated and 85 were randomized to standard care with or without rifaximin for 42 days. Changes in markers of inflammation, BT, and fibrosis were the primary outcomes. BT was measured using plasma 16S rRNA, lipopolysaccharide-binding protein, and lipopolysaccharide, whereas hyaluronan was used to measure fibrosis. Tumor necrosis factor receptor 1 (TNFR1) and soluble cluster of differentiation 14 (sCD14) assessed inflammation. 16S rRNA reduced from baseline (median 146 copies/µL, interquartile range [IQR] 9, 537) to day 42 in the rifaximin group (median 63 copies/µL, IQR 12, 196),
Rotavirus breakthrough infections responsible for gastroenteritis in vaccinated infants who presented with acute diarrhoea at University Teaching Hospitals, Children's Hospital in 2016, in Lusaka Zambia.
(2021) Simwaka J; Seheri M; Mulundu G; Kaonga P; Mwenda JM; Chilengi R; Mpabalwani E; Munsaka S; Department of Virology, Diarrhoea Pathogens Research Unit and WHO AFRO Rotavirus Regional Reference Laboratory, South African Medical Research Council, Sefako Makgatho Health Sciences University, Pretoria, South Africa.; Center for Infectious Disease Research in Zambia, Lusaka, Zambia.; Department of Biomedical Sciences, School of Health Sciences, University of Zambia, Lusaka, Zambia.; Department of Pathology and Microbiology, School of Medicine, University of Zambia, Lusaka, Zambia.; Department of Internal Medicine, University Teaching Hospital, Tropical Gastroenterology and Nutrition Group, Lusaka, Zambia.; Department of Paediatric and Child Health, School of Medicine, University of Zambia, Lusaka, Zambia.; Department of Epidemiology and Biostatistics, School of Public Health, University of Zambia, Lusaka, Zambia.; World Health Organization Regional Office for Africa (WHO/AFRO), Brazzaville, Congo.; CIDRZ; Centre for Infectious Disease Research in Zambia (CIDRZ)
BACKGROUND: In Zambia, before rotavirus vaccine introduction, the virus accounted for about 10 million episodes of diarrhoea, 63 000 hospitalisations and 15 000 deaths in 2015, making diarrhoea the third leading cause of death after pneumonia and malaria. In Zambia, despite the introduction of the vaccine acute diarrhoea due to rotaviruses has continued to affect children aged five years and below. This study aimed to characterise the rotavirus genotypes which were responsible for diarrhoeal infections in vaccinated infants aged 2 to 12 months and to determine the relationship between rotavirus strains and the severity of diarrhoea in 2016. METHODS: Stool samples from infants aged 2 to 12 months who presented to the hospital with acute diarrhoea of three or more episodes in 24 hours were tested for group A rotavirus. All positive specimens that had enough sample were genotyped using reverse transcriptase Polymerase Chain Reaction (RT-PCR). A 20-point Vesikari clinical score between 1-5 was considered as mild, 6-10 as moderate and greater or equal to 11 as severe. RESULTS: A total of 424 stool specimens were tested of which 153 (36%, 95% CI 31.5% to 40.9%) were positive for VP6 rotavirus antigen. The age-specific rotavirus infections decreased significantly (p = 0.041) from 2-4 months, 32.0% (49/118) followed by a 38.8% (70/181) infection rate in the 5-8 months' category and subsequently dropped in the infants aged 9-12 months with a positivity rate of 27.2%. 38.5% of infants who received a single dose, 34.5% of those who received a complete dose and 45.2% (19/42) of the unvaccinated tested positive for rotavirus. The predominant rotavirus genotypes included G2P[6] 36%, G1P[8] 32%, mixed infections 19%, G2P[4] 6%, G1P[6] 4% and G9P[6] 3%. DISCUSSION AND CONCLUSION: Results suggest breakthrough infection of heterotypic strains (G2P[6] (36%), homotypic, G1P[8] (32%) and mixed infections (19%) raises concerns about the effects of the vaccination on the rotavirus diversity, considering the selective pressure that rotavirus vaccines could exert on viral populations. This data indicates that the rotavirus vaccine has generally reduced the severity of diarrhoea despite the detection of the virus strains.