Helicobacter pylori cag pathogenicity island genotype diversity within the gastric niche of a single host

1 Departamento de Microbiología, Parasitología e Inmunología, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina 2 Servicio de Endoscopia, Hospital General de Agudos Juan A Fernández, Buenos Aires, Argentina 3 Servicio de Gastroenterología, Hospital Escuela ‘Don José de San Martín’ Facultad de Medicina, Buenos Aires, Argentina Correspondence Mariana Catalano catalanoma{at}gmail.com.ar Received 10 August 2006 Accepted 9 January 2007 cag pathogenicity island (PAI) integrity was investigated in isolates from multiple biopsies recovered from 40 patients in an attempt to determine the co-existence of a varying cag PAI-positive to cag PAI-negative ratio in a single host. Six biopsies were obtained from each patient during the same endoscopic session. cag PAI analysis included amplification of seven loci ( cagA , cagE , cagG , cagM , cagT , HP0527 and HP0524) and the left end of cag II (LEC). Absence of the island was confirmed by empty-site PCR. lspA - glmM RFLP and random amplified polymorphic DNA PCR were used for strain delineation. The number of biopsies with Helicobacter pylori -positive culture ranged from three to six per patient and a total of 218 isolates were recovered. Mixed infection was only found in two patients. Nearly one-third of the 40 patients harboured isolates with an intact cag PAI in all niches, another third of the isolates were empty-site-positive in all niches, whilst the remaining third of the isolates had a disrupted cag PAI in all or at least one of the niches. Co-existence of variants of the same strain with different cag PAI genotypes was observed in one-quarter of patients. The variations in cag PAI genotype included co-existence of: diverse cag PAI deletions in different niches, variants with intact and with partially deleted islands, variants with empty-site-positive and with partially deleted cag PAIs, and variants with an intact cag PAI and with empty-site-positive. Half of the patients with different cag PAI genotypes harboured an intact cag PAI in at least one niche. Co-existence of diverse genotypes of putative virulence factors in a single host must be considered when drawing a correlation with clinical presentation. Abbreviations: LEC, left end of the cag PAI; PAI, pathogenicity island; RAPD, random amplified polymorphic DNA.