CagA antibodies as a marker of virulence in chilean patients with Helicobacter pylori infection.
BACKGROUND
The bacterial and host factors that influence the clinical outcomes of the Helicobacter pylori infection have not been fully identified. Cytotoxin-associated gene product (CagA), one of the virulence factors, has been associated with a more aggressive form of infection. The authors studied the relationship between CagA status and clinical outcome in Chilean children and adults with H. pylori infection.


METHODS
One hundred eighty consecutive patients undergoing upper gastrointestinal endoscopic analysis were enrolled after informed consent was obtained. Rapid urease test and histologic analysis were used to detect H. pylori infection. IgA and IgG antibodies to H. pylori whole cell antigen preparation and IgG antibodies to CagA were measured by enzyme-linked immunosorbent assay (ELISA).


RESULTS
H. pylori infection was detected in 42% of the patients by biopsy or urease test and in 38% and 20% of patients by IgG and IgA antibodies, respectively. The prevalence of H. pylori either by the invasive or the serologic tests was directly related to patient age. Among patients with H. pylori, there was no significant association between age and prevalence of CagA. Nearly 70% of the patients with H. pylori and peptic ulcer disease had CagA-positive strains. In contrast, only 49% of the patients with chronic gastritis alone had CagA-positive strains (P < 0.05).


CONCLUSIONS
In Chile, patients infected with H. pylori have a proportion of CagA-positive strains similar to that reported in developed countries. CagA prevalence was not significantly different in adults and children infected with H. pylori, suggesting that variations in clinical outcome may be related to host immune or environmental factors.
Department of Pediatrics, School of Medicine, Pontificia Universidad Católica, Santiago, Chile. pharris@med.puc.cl
Paul R
PR
Harris
Alex
A
Godoy
Silvana
S
Arenillas
Francisca
F
Riera
Daniela
D
García
Helly
H
Einisman
Alfredo
A
Peña
Antonio
A
Rollán
Ignacio
I
Duarte
Ernesto
E
Guiraldes
Guillermo
G
Perez-Perez
D015746:Abdominal Pain; D000293:Adolescent; D000328:Adult; D000907:Antibodies, Bacterial / Q000097:blood*; D000942:Antigens, Bacterial / Q000276:immunology*; D001426:Bacterial Proteins / Q000276:immunology*; D001706:Biopsy; D002648:Child; D002677:Chile; D004381:Duodenal Ulcer / Q000175:diagnosis / Q000382:microbiology / Q000473:pathology; D016099:Endoscopy, Gastrointestinal; D005756:Gastritis / Q000382:microbiology / Q000473:pathology; D016481:Helicobacter Infections / Q000175:diagnosis / Q000382:microbiology*; D016480:Helicobacter pylori / Q000276:immunology* / Q000472:pathogenicity; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D011706:Pyloric Antrum / Q000473:pathology; D012680:Sensitivity and Specificity; D014510:Urease
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D007070:Immunoglobulin A; D007074:Immunoglobulin G; C080866:cagA protein, Helicobacter pylori; D014510:Urease