RESUMEN
BACKGROUND: The presence of Helicobacter pylori DNA from saliva has been demonstrated by polymerase chain reaction; however, the culture of H. pylori is quite difficult. Because isolation of H. pylori strains from saliva plays an important role in epidemiological and pathogenic studies, our study was aimed to establish the H. pylori culture method from saliva and the compared detection limit between cultures after HCl-urea treatment and PCR. METHODS: A strain of H. pylori was cultured, diluted and mixed with saliva of an H. pylori-negative volunteer to make a final concentration of a 10(1)-10(5) colony forming unit (CFU)/mL saliva. Each concentration of samples was treated with various concentrations of HCl-urea (pH 1.2) to suppress other bacteria. Paired samples (HCl-urea treated and untreated) were streaked on horse blood agar and cultured for 3-10 days at 37 degrees C in microaerophilic condition. The DNA templates were extracted from the same concentrations of HCl-urea treated bacterial suspensions in saliva and PCR was performed. RESULTS: The detection limit of the culture after HCl-urea treatment was 10(3) CFU/mL of saliva and that of the PCR after HCl-urea treatment was 10(2) CFU/mL of saliva. CONCLUSIONS: A culture after HCl-urea treatment for H. pylori would be an effective method for isolation of H. pylori from saliva; however, this method is less sensitive than PCR as far as the detection limit is concerned. A combination of both methods would be an effective method for detecting H. pylori from saliva.