Analysis of genetic variability, antimicrobial susceptibility and virulence markers in Helicobacter pylori identified in Central Italy.
OBJECTIVE
To assess the relationship between the presence of mixed infection of Helicobacter pylori and both antimicrobial susceptibility and virulence markers.


METHODS
Thirty-six patients with H. pylori infection were included in the study. Three colonies were selected from each positive biopsy sample collected from each host for a total of 108 H. pylori strains. The genetic variability was evaluated through the amplified fragment length polymorphism (AFLP) analysis; the antibiotic susceptibility to amoxicillin, clarithromycin, moxifloxacin, rifabutin and tinidazole was determined using the minimum inhibitory concentrations (MICs) with the agar dilution method. Moreover, the vacA, cagA, iceA and babA2 statuse were detected by polymerase chain reaction (PCR).


RESULTS
There was a strong connection between mixed H. pylori infection and antimicrobial resistance. In particular, H. pylori strains with genetic variability, in the same host, expressed more resistance to clarithromycin, moxifloxacin and tinidazole than that expressed in strains with a unique genetic host pattern. VacA s1m1/s1m2 genotypes were found in 70% of strains isolated in mixed infection, whereas the same allelic combinations were found in 42% of strains, isolated in single infection. The cagA(+) status prevailed both in patients with mixed (97%) and in those with single infection (85%) without significant differences. The iceA1 status was more commonly found in patients with mixed infection, whereas the babA2 status was significantly prevalent in single H. pylori infection.


CONCLUSIONS
Mixed H. pylori infection harbouring in one patient is significantly related to strains that are more resistant to antibiotics and with a more virulent genotype (vacA s1m1/s1m2, cagA, iceA1) than strains responsible for single infection.
Cellini
Luigina
L
Department of Biomedical Sciences, University "G. d'Annunzio", Chieti, Italy. l.cellini@unich.it
Grande
Rossella
R
Di Campli
Emanuela
E
Di Bartolomeo
Soraya
S
Capodicasa
Simona
S
Marzio
Leonardo
L
D000328:Adult; D000368:Aged; D000890:Anti-Infective Agents / Q000494:pharmacology*; D001706:Biopsy; D004269:DNA, Bacterial / Q000235:genetics*; D024881:Drug Resistance, Bacterial; D005260:Female; D005838:Genotype; D016481:Helicobacter Infections / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D016480:Helicobacter pylori / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D006801:Humans; D007413:Intestinal Mucosa / Q000382:microbiology / Q000473:pathology; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D014774:Virulence
D000890:Anti-Infective Agents; D004269:DNA, Bacterial