title: Relationship between tobacco, cagA and vacA i1 virulence factors and bacterial load in patients infected by Helicobacter pylori.
abstract: OBJECTIVE
  Several biological and epidemiological studies support a relationship between smoking and Helicobacter pylori (H. pylori) to increase the risk of pathology. However, there have been few studies on the potential synergistic association between specific cagA and vacA virulence factors and smoking in patients infected by Helicobacter pylori. We studied the relationship between smoking and cagA, vacA i1 virulence factors and bacterial load in H. pylori infected patients.
  
  
  METHODS
  Biopsies of the gastric corpus and antrum from 155 consecutive patients in whom there was clinical suspicion of infection by H. pylori were processed. In 106 patients H. pylori infection was detected. Molecular methods were used to quantify the number of microorganisms and presence of cagA and vacA i1 genes. A standardized questionnaire was used to obtain patients' clinical data and lifestyle variables, including tobacco and alcohol consumption. Adjusted Odds Ratios (ORadjusted) were estimated by unconditional logistic regression.
  
  
  RESULTS
  cagA was significantly associated with active-smoking at endoscope: ORadjusted 4.52. Evidence of association was found for vacA i1 (ORadjusted 3.15). Bacterial load was higher in active-smokers, although these differences did not yield statistical significance (median of 262.2 versus 79.4 copies of H. pylori per cell).
  
  
  CONCLUSIONS
  The association between smoking and a higher risk of being infected by a virulent bacterial population and with higher bacterial load, support a complex interaction between H. pylori infection and environmental factors.
authors: Departamento de Salud Pública, Universidad de Cantabria, Santander, Spain; IDIVAL-Instituto de Investigación Marqués de Valdecilla, Santander, Spain.
authors: Miguel
authors: M
authors: Santibáñez
authors: Microbiology S. Elche University General Hospital, Elche (Alicante), Spain.
authors: Estefanía
authors: E
authors: Aguirre
authors: Microbiology S. Elche University General Hospital, Elche (Alicante), Spain.
authors: Sofía
authors: S
authors: Belda
authors: CIBER in Epidemiology and Public Health (CIBERESP), Madrid, Spain; Environmental and Cancer Epidemiology Unit, National Center of Epidemiology, ISCIII, Madrid, Spain.
authors: Nuria
authors: N
authors: Aragones
authors: Digestive Medicine S. Elche University General Hospital, Elche (Alicante), Spain.
authors: Jesús
authors: J
authors: Saez
authors: Microbiology S. Alicante University General Hospital, Alicante, Spain; Miguel Hernández University, Elche, Spain.
authors: Juan Carlos
authors: JC
authors: Rodríguez
authors: Microbiology S. Elche University General Hospital, Elche (Alicante), Spain.
authors: Antonio
authors: A
authors: Galiana
authors: Digestive Medicine S. Elche University General Hospital, Elche (Alicante), Spain.
authors: Javier
authors: J
authors: Sola-Vera
authors: Microbiology S. Elche University General Hospital, Elche (Alicante), Spain.
authors: Montserrat
authors: M
authors: Ruiz-García
authors: Departamento de Enfermería, Universidad de Cantabria, Santander, Spain.
authors: María
authors: M
authors: Paz-Zulueta
authors: Departamento de Enfermería, Universidad de Cantabria, Santander, Spain.
authors: Raquel
authors: R
authors: Sarabia-Lavín
authors: Digestive Medicine S. Elche University General Hospital, Elche (Alicante), Spain.
authors: Alicia
authors: A
authors: Brotons
authors: Microbiology S. Elche University General Hospital, Elche (Alicante), Spain.
authors: Elena
authors: E
authors: López-Girona
authors: Digestive Medicine S. Elche University General Hospital, Elche (Alicante), Spain.
authors: Estefanía
authors: E
authors: Pérez
authors: Digestive Medicine S. Elche University General Hospital, Elche (Alicante), Spain.
authors: Carlos
authors: C
authors: Sillero
authors: Microbiology S. Elche University General Hospital, Elche (Alicante), Spain; Miguel Hernández University, Elche, Spain.
authors: Gloria
authors: G
authors: Royo
mesh_terms: D000942:Antigens, Bacterial / Q000378:metabolism*; D058491:Bacterial Load; D001426:Bacterial Proteins / Q000378:metabolism*; D005260:Female; D016481:Helicobacter Infections / Q000378:metabolism*; D006801:Humans; D008297:Male; D012907:Smoking / Q000009:adverse effects*; D011795:Surveys and Questionnaires; D037521:Virulence Factors / Q000378:metabolism*
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C074689:VacA protein, Helicobacter pylori; D037521:Virulence Factors; C080866:cagA protein, Helicobacter pylori