Clarithromycin resistance in Helicobacter pylori and its molecular determinants in Northern Spain, 2013-2015.
OBJECTIVES
Clarithromycin resistance (CLR-R) is the main reason for failure of Helicobacter pylori infection treatment, which is frequently empirically prescribed due to the erroneous belief that culture for susceptibility testing is difficult. The aim of this study was to determine CLR-R in a region of southern Europe and to evaluate the utility of a PCR sequencing assay applied on gastroduodenal biopsies in detecting H. pylori and clarithromycin (CLR) susceptibility.


METHODS
The susceptibility of all H. pylori isolates obtained by culture during 2013-2015 was determined by Etest. During 2014-2015, H. pylori detection and CLR susceptibility were also studied by PCR followed by sequencing performed on gastroduodenal biopsies. Point mutations in the 23S rRNA gene were studied in all CLR-resistant isolates in 2014.


RESULTS
Of 1986 H. pylori isolates obtained by culture (63 from children and 1923 from adults), 349 (17.6%) were CLR-resistant [21/63 (33.3%) in children and 328/1923 (17.1%) in adults; P<0.001], of which 31.5% were also resistant to levofloxacin. The main mutations detected were A2147G (79.8%), A2146G (17.2%) and A2146C (2%). Concordance between the PCR sequencing assay on biopsies and CLR susceptibility by Etest after culture was 89.8%.


CONCLUSIONS
CLR-R was high in Gipuzkoa, northern Spain. The molecular PCR method performed directly on biopsies was a good alternative to the traditional Etest susceptibility method and was an aid when culture was non-viable.
['Tamayo|Esther|E|', 'Montes|Milagrosa|M|', 'Fernández-Reyes|María|M|', 'Lizasoain|Jacobo|J|', 'Ibarra|Begoña|B|', 'Mendarte|Usua|U|', 'Zapata|Eva|E|', 'Mendiola|Josune|J|', 'Pérez-Trallero|Emilio|E|']
D000293:Adolescent D000328:Adult D000900:Anti-Bacterial Agents D001706:Biopsy D002648:Child D002675:Child, Preschool D017291:Clarithromycin D004269:DNA, Bacterial D004275:DNA, Ribosomal D052978:Disk Diffusion Antimicrobial Tests D024881:Drug Resistance, Bacterial D005753:Gastric Mucosa D016481:Helicobacter Infections D016480:Helicobacter pylori D006801:Humans D007223:Infant D007231:Infant, Newborn D007413:Intestinal Mucosa D017354:Point Mutation D016133:Polymerase Chain Reaction D012338:RNA, Ribosomal, 23S D017422:Sequence Analysis, DNA D013030:Spain D055815:Young Adult
Clarithromycin Helicobacter pylori Gastroduodenal biopsy Mutation 23S rRNA Susceptibility-guided treatment