Date of Award

2009

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Science

First Advisor

Dr. Abdelmajeed AI Khajah

Second Advisor

Dr. Faroukhmin Sheick

Third Advisor

Dr. Rabah Iratni

Abstract

Helicobacter pylori is a flagellated corkscrew, slow growing neutrophilic gram negative ureolytic organism. It has an extraordinary ability to establish infection in human stomach that can last for years or decades. Its eradication remains an important public health challenge especially in light of broadening indications and increasing antimicrobial resistance.

AIM: i) Identification of H. pylori in UAE patients ii) Determination of the prevalence of antibiotic resistance genes (mutation in 23S rRNA gene in clarithromycin, and deletion in RdxA gene in metronidazole) among H. pylori strains isolated from U.A.E patients by using molecular methods, iii) Ascertain whether Cag A- positive H. pylori strains correlates with the antibiotic resistance strains or not and iv) Screening for new H. pylori strains in UAE through the phylogenetic analysis of the 23S rRNA middle region of the gene.

METHODS: The identification of H. pylori in UAE patients was carried on by primary screening for H. pylori using CLO test while the confirmation test were done using PCR technique. The prevalence of antibiotic resistance genes (mutation in 23S rRNA gene in clarithromycin, and deletion in RdxA gene in metronidazole) among H. pylori strains isolated from U.A.E patients and Cag A gene relation between this gene and antibiotic resistant genes were studied by PCR and sequencing technique. Phylogenetic analysis of the 23S rRNA gene was analyzed by using the software ClustalX, version 2. Reference sequences used in the alignment was obtained from NCBI data base for all 23s rRNA from different H. pylori strains.

RESULTS: 26 out of 90 biopsy samples were positive for H. pylori using PCR whereas only 22 were positive when tested by CLO test. Resistance to clarithromycin and metronidazole was detected in 9 and 3 of strains, respectively. Of the clarithromycin resistant strains, 2 strains had the A2142G mutation in the 23S rRNA gene, 5 strains in A2143G, 1 strain in A2143C and 1 strain of highly changed in sequence. Of the metronidazole resistant strains, deletion in rdxA gene was detected in 3 strains which were negative for CLO test. DNA sequence phylogenetic analysis of the 23S rRNA middle region of the gene indicates that the strains from UAE harbor a unique 23S rRNA sequences that is common among isolates from the UAE patients and different than other strains published in the NCBI database.

CONCLUSION: This study is the first time done in the UAE where a significant proportion of gastric mucosal biopsies obtained in the UAE are positive for Genes associated with Clarithromycin and Metronidazole resistance (mainly in Clarithromycin). A2143G remains the most prevalent point mutation involved, thus suggesting that new therapeutic strategies are needed

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