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Now showing 1 - 5 of 446
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    Genetic determinants of Helicobacter pylori resistance to fluoroquinolones in phenotypically resistant isolates.
    (Makerere University, 2025-11) Namasinga, Agatha
    Background:Helicobacter pylori is a Gram-negative bacterium that infects the gastric mucosa of approximately 50% of the global population. Although most infections are asymptomatic, H. pylori is a leading cause of peptic ulcers and gastric cancer, which accounts for over 700,000 deaths annually. Fluoroquinolones, such as levofloxacin, are used in second-line therapy for H. pylori eradication. However, increasing resistance to fluoroquinolones, driven by point mutations in the gyrA and gyrB genes, poses a significant public health challenge. Despite this, data on the genetic basis of fluoroquinolone resistance in H. pylori isolates in Uganda remains scarce.Objective:This study aims to identify the genetic determinants of fluoroquinolone resistance in phenotypically resistant H. pylori isolates using Sanga sequencing.Methods: A cross-sectional study was conducted on stored isolates collected from H. pylori symptomatic patients who tested phenotypically resistant to fluoroquinolones. A total of 46 isolates underwent DNA extraction and conventional PCR, yielding 24 samples with amplicons, evidenced by bands on agarose gel electrophoresis. The 24 samples were subjected to sanga sequencing ABI 310, which resulted in 7 good sequences.Results:The 7 sequences that were identified and were aligned with the references genome, did not show any mutations at the codons 87 and 91 of gyrA or any other Quinolone Resistance Determining Region (QRDR).Conclusion: This study demonstrated that while PCR amplification of the gyrA gene in Helicobacterpylori isolates was moderately successful, sequencing efficiency remained low due to challenges related to DNA quality, amplification specificity, and template purity. Keywords: Helicobacter pylori, fluoroquinolone resistance, gyrA mutations, Uganda, Sanga sequencing, antimicrobial resistance.
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    Genetic determinants of tetracycline resistance in Helicobacter pylori isolates
    (Makerere University, 2025) Nyaburu, Caroline
    Background: Helicobacter pylori is a gram-negative, spiral-shaped bacterium that colonizes the stomach mucosa and causes gastritis, peptic ulcers, gastric adenocarcinoma, and MALT lymphoma. Globally, over 50% of people are infected, with rates reaching 70.1% in Africa and over 80% in Nigeria. Treatment typically involves triple therapy using two antibiotics and a proton pump inhibitor or bismuth, often including clarithromycin, amoxicillin, or metronidazole. Tetracycline is added in quadruple therapy for resistant cases. Tetracycline, a broad-spectrum antibiotic that inhibits protein synthesis by binding to the 30S ribosomal subunit, faces rising resistance due to triple base pair mutations in the H. pylori 16SrRNA gene. Objectives of the study: In this study, we determined the frequency of mutations in the 16S rRNA genes of H. pylori isolates that are phenotypically resistant to tetracycline, and also determined the proportion of tetracycline susceptible H. pylori isolates that harbor mutations in the 16S rRNA genes. We then compared the frequency of the mutations to the pre-determined MIC values of the H. pylori isolates. Methods: A conventional PCR and Sanger sequencing were performed to find alterations in 16S rRNA genes of H. pylori isolates linked to resistance to tetracycline. Results: Sequence analysis of the tetracycline binding site on the 16S rRNA gene of H. pylori fragment revealed multiple SNPs, primarily transition substitutions A-G, C-T accounting for over 90% of all mutations. The most recurrent substitutions included A247G, C252T, C255T, G265T, and T278A, which appeared in more than 80% of the resistant isolates. Downstream mutations beyond position 265 bp were associated with markedly elevated MICs. Conclusion: This study demonstrates that tetracycline resistance in H. pylori arises from cumulative single-nucleotide polymorphisms within the 16S rRNA gene, in the tetracycline binding region A/C. Mutation frequency and positional clustering show a direct relationship with MIC, making genotypic variation to translate into phenotypic resistance. Key words: Phenotypic resistance, MICs, Genetic determinants, Tetracycline, H. pylori, Mutations, Single nucleotide polymorphisms.
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    Genetic determinants of Helicobacter pylori resistance to metronidazole in Uganda
    (Makerere University, 2025) Kazibwe, Colline
    Background. About half of the world's population is affected with H. pylori infections, which typically start in childhood and can progress to chronic infections. It causes a number of illnesses, the most common being peptic ulcer disease and gastritis. Proton pump inhibitors and a combination of antimicrobial medicines are recommended for the eradication of H. pylori. These antimicrobial agents include; clarithromycin (CLA), metronidazole, and amoxicillin as first line, while others such as fluoroquinolones (FLQ) and tetracycline are used in second-line regimens. Resistance to metronidazole by Helicobacter pylori has caused its elimination using metronidazole containing regimens ineffective. Although it is believed that mutations in the rdxA and frxA genes cause H. pylori resistance to metronidazole, little is known about the genetic factors that contribute to this resistance in patients from Uganda. Objectives; To determine the frequency of rdxA gene mutations of H. pylori isolates from Ugandan patients. To determine rdxA mutations of H. pylori isolates that correlate with the resistant phenotype. Methods; DNA was be extracted from both resistant and susceptible isolates. The rdxA genes were amplified using conventional PCR, and their sequences determined using Sanger sequencing. The sequences were then analyzed for sequence identity and similarity using bioinformatics tools at NCBI. Sequence comparison with reference rdxA gene of sequence KC491784.1 Helicobacter pylori strain IR9 isolate HP9 was the performed in Bio edit software 7.2. Results; Sequences obtained were dissimilar to those of the reference sequence which indicated that the primer sets used did not amplify the target rdxA gene either due mutation at the sites where primer had to anneal or the primer sets were not specific for the target gene.
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    Prevalence, antimicrobial resistance profiles and factors associated with asymptomatic bacteriuria among pregnant women attending Kiswa centre iii, Kampala.
    (Makerere University, 2025-10-02) Sajja, Kenneth
    Asymptomatic bacteriuria (ABU) is a common clinical condition during pregnancy, associated with significant maternal and fetal complications if untreated. Despite its importance, routine screening and antimicrobial resistance (AMR) profiling remain limited in many low resource settings, including Uganda. The study aimed to determine the prevalence, antimicrobial resistance profiles, and associated risk factors of asymptomatic bacteriuria among pregnant women attending Kiswa Health Center III in Kampala, Uganda.A cross sectional study was conducted from March to August 2024 among 165 pregnant women without urinary tract symptoms. Midstream urine samples were collected and cultured for bacterial isolation. Identification and antibiotic susceptibility testing were performed using standard microbiological techniques and CLSI guidelines. Data on sociodemographic and clinical factors were collected via structured interviews and analyzed using SPSS. The prevalence of ABU was 25.5%, with Escherichia coli being the most frequently isolated pathogen (28%). Other bacteria included Citrobacter freundii, Klebsiella pneumonia, Straphylococcus saprophyticus, and Pseudomonas species. High resistance was observed against ampicillin (64.3%), trimethoptim sulfamethoxale(70.6%), and ciproflaxin (50%). Previous antibiotic use was significantly associated with reduced ABU prevalence (p<0.001) while primigravidity was associated with higher risk (p=0.039). ABU prevalence at KHCIII is high, with multidrug-resistant E.coli being the predominant isolate. Routine urine culture and sensitivity testing should be integrated into antenatal care to ensure early detection and appropriate management. Public health interventions focusing on hygiene education and antimicrobial stewardship are urgently needed especially in rural and public health facilities as they carry a big number of clients and patients from various local communities.
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    Bacteria aetiologies and antibiotic resistance profiles in pediatric urinary tract infections associated with congenital abnormalities of the kidney and urinary tract at Entebbe Children's Surgical Hospital
    (Makerere University, 2025) Apio, Priscilla
    Background: Urinary Tract Infections (UTIs) are among the most common bacterial infections in childhood. Malformation of the urinary tract often leads to recurrent infections. The increased risk of UTIs in children with these malformations often leads to a higher need for antibiotic treatment which can result in antimicrobial resistance. This study aimed to investigate the bacterial etiologies and antibiotic resistance profiles in urinary tract infections among pediatric patients with anatomical urological abnormalities at the Children's Surgical Hospital Entebbe (CSHE). Methods: A quantitative cross-sectional study was, conducted at the CSHE, from January 2024 to May 2025. Pediatric patients below 18 years with CAKUT except bladder exstrophy and urine analysis suggestive of UTI were sampled purposively. A structured questionnaire was used to collect data and midstream urine, neonatal bagged urine, in and out foley, or suprapubic urine was collected aseptically for urinalysis and isolated organisms antibiotic resistance profiles tested. Descriptive statistics and logistic regression in Stata 18 were used to analyze the data. Results: Of 101 participants 35.6% were aged 1-3 years and 90.1% male. The prevalence of UTI was 18.8%. Bacteria isolates were predominantly gram-negative with Escherichia coli (42.1%) and Pseudomonas aeruginosa (26.3%) being the commonly isolated bacteria. E.coli had high sensitivity to amikacin, gentamicin, meropenem, and chloramphenicol (100%), but exhibited complete resistance to amoxicillin-clavulanic acid and trimethoprim-sulfamethoxazole. P.aeruginosa was completely sensitive to ciprofloxacin (100%) but had decreased sensitivity (60%) for amikacin, gentamicin, and meropenem. Enterococcus faecium was completely resistant to ampicillin, ciprofloxacin, and gentamicin synergy but sensitive to vancomycin. Male sex (AOR = 0.03; 95% CI = 0.00–0.52, p = 0.017) and recent hospitalization (AOR = 12.43; 95% CI = 1.08–141.88, p = 0.042) were statistically significant independent predictors of UTI. Conclusion: UTIs among children with CAKUT were primarily caused by drug-resistant Gram-negative organisms. Male sex was protective against UTI, while recent hospitalization significantly increased UTI risk. The findings emphasize the importance of routine culture and sensitivity testing to guide appropriate antibiotic use.