Primary clarithromycin resistance in Italy assessed on Helicobacter pylori DNA sequences by TaqMan real time polymerase chain reaction.

BACKGROUND: Helicobacter pylori clarithromycin resistance is increasing worldwide and different mutations are involved in its mechanisms. Recently, molecular methods have been proposed to assess these mutations. AIM: To assess prevalence of primary clarithromycin resistance in two Italian areas, and the distribution of involved mutations, by using a novel method for real-time polymerase chain reaction. METHODS: Two hundred and thirty-two H. pylori-positive patients undergoing oesophagogastroduodenoscopy in two Italian towns (Rome, centre Italy; Foggia, south Italy) were enrolled. Helicobacter pylori infection was detected by histology, rapid urease and urea breath tests. Clarithromycin resistance was assessed by TaqMan real-time polymerase chain reaction on paraffin-embedded antral biopsies. Results Primary clarithromycin resistance was detected in 62 (26.7%) patients. Its prevalence did not differ between the two areas (31.5%, centre vs. 23.3%, south; P=0.17) and between non-ulcer dyspepsia and peptic ulcer patients (28.4% vs. 20.7%, P=0.2). The A2143G point mutation was detected in 35 (56.4%) patients, A2142G in 14 (22.6%), A2142C in eight (12.9%), whilst a double mutation (A2143G plus A2142C or A2142G) was present in the remaining five (8.1%) cases. CONCLUSIONS: Our study found that primary clarithromycin resistance is highly prevalent in both central and southern Italy, and that A2143G is the most frequent point mutation involved in these areas