Virulence factors and antimicrobial resistance in H. pylori clinical isolates by a multiple correspondence analysis

Abstract number: P1316

Garcia-Campos J.A., Alarcon T., Domingo D., Lopez-Brea M.

The aim of this study was to determine the presence of different virulence factors and antimicrobial resistance in H. pylori clinical isolates and to analyse the results obtained by a multiple correspondence analysis (MCA).

Methods: 70 H. pylori strains were obtained from patients attending to the Gastroenterology Unit due to different symptomatology. 46 out of the 75 suffered of gastritis and 29 of peptic ulcer. Upper endoscopy was performed and biopsy cultured following standard methodology. DNA was extracted from a 48 h culture and PCR performed to detect cagA gene, vacA s1- and s2-alleles, babA2 gene, hpaA alleles and hopQ alleles. Specific primers for the cag empty site were also used to confirm the absence of the cagPAI (ES-cagA). All PCR products were analysed by agarose gel stained with ethidium bromide. Lewis antigen was determined by an Enzimoimmuno assay using monoclonal anti-LewisX and anti-LewisY and alcaline phosphatase labelled secondary antidodies. Metronidazole and clarithromycin resistance was determined by E-test.

Results: Three groups were detected by MCA: (1) strains positive for cagA gene (non discrepant with ES-cagA), vacAs1, hopQ type I-II, negative for babA2 and clarithromycin and metronidazole susceptible (group A). (2) Strains negative for cagA (discrepant with ES-cagA) and positive for vacAs2, hopQ type II, babA2, hpaA2, clarithromycin and metronidazole resistant and expressing Lewis antigen (LeXY or LeY) (group B). (3) A heterogeneous group (group C). Same results were detected when a dendogram for cluster analysis was drawn.

When the MCA analysis was performed in strains form ulcer patients the same 3 groups were detected with small differences. In strains from gastritis higher differences were found. cagA+, vacAs1, hpaA1 and hopQ I-II strains were associated with clarithromycin and metronidazole resistance (in ulcer strains were associated with susceptible ones), the presence of babA2, the expression of LewisXY antigen and the discrepancies with ES-cagA.

Conclusions: Strains with more virulence factors grouped together when MCA was performed. Moreover, in strains from gastritis virulence genes were associated with clarithromycin and metronidazole resistance whilst in ulcer strains they were associated with susceptible ones.

Acknowledgement: FIS-PI052442