Comparison of three PCR methods for detection of Helicobacter pylori DNA and detection of cagA gene in gastric biopsy specimens.
OBJECTIVE
To comparatively evaluate PCR and other diagnostic methods (the rapid urease test and / or culture) in order to determine which of the three PCR methods (ureA, glmM and 26-kDa, SSA gene) was most appropriate in the diagnosis of Helicobacter pylori (H pylori ) infection and also to evaluate the detection of a putative virulence marker of H pylori, the cagA gene, by PCR in biopsy specimens.


METHODS
One hundred and eighty-nine biopsy specimens were collected from 63 patients (three biopsies each) undergoing upper gastroduodenal endoscopy for various dyspeptic symptoms. The PCR methods used to detect H pylori DNA directly from biopsies were the glmM, 26-kDa, ureA and then cagA was used to compare the culture technique and CLO for urease with the culture technique being used as the gold standard.


RESULTS
Thirty-five percent of the biopsies were positive for H pylori DNA using the 3 PCR methods, while 68% of these were positive for the cagA gene. Twenty-four percent of the biopsies were negative for H pylori DNA in all PCR methods screened. The remaining 41% were either positive for ureA gene only, glmM only, 26-kDa only, or ureA + glmM, ureA + 26-kDa, glmM + 26-kDa. Out of the 35% positive biopsies, 41% and 82% were positive by culture and CLO respectively, while all negative biopsies were also negative by culture and cagA. Cag A+ infection was also predominantly found in H pylori DNA of the biopsies irrespective of the clinical diagnosis.


CONCLUSIONS
This method is useful for correctly identifying infections caused by H pylori and can be easily applied in our laboratory for diagnostic purposes.
Smith
S-I
SI
Molecular Biology and Biotechnology Division, Nigerian Institute of Medical Research, P.M.B. 2013, Yaba, Lagos, Nigeria. stellaismith@yahoo.com
Oyedeji
K-S
KS
Arigbabu
A-O
AO
Cantet
F
F
Megraud
F
F
Ojo
O-O
OO
Uwaifo
A-O
AO
Otegbayo
J-A
JA
Ola
S-O
SO
Coker
A-O
AO
D000942:Antigens, Bacterial / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D001706:Biopsy; D005753:Gastric Mucosa / Q000382:microbiology / Q000473:pathology; D016481:Helicobacter Infections / Q000382:microbiology / Q000473:pathology*; D016480:Helicobacter pylori / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity; D006801:Humans; D010733:Phosphoglucomutase / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D014510:Urease / Q000235:genetics; D014774:Virulence
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C080866:cagA protein, Helicobacter pylori; D014510:Urease; D010733:Phosphoglucomutase