Optimal combination of media for primary isolation of Helicobacter pylori from gastric biopsy specimens.

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RESUMO

The aim of the present study was to compare eight media, four nonselective and four selective media, to determine the best combination of media for the primary isolation of Helicobacter pylori. Over a period of 5 months, mucosal antral biopsy specimens were obtained from 222 consecutive dyspeptic patients undergoing endoscopy. Biopsy samples were plated in parallel on all eight media. Egg yolk emulsion agar (EYE), Skirrow's medium, Dent's medium, and modified Thayer-Martin medium were used as selective media; modified chocolate agar (MCHOC), Triptycase soy agar (TSA), brucella agar, and brain heart infusion agar were used as nonselective media. Overall, by using these eight media, H. pylori was recovered from biopsy specimens from 114 of 222 patients, yielding an isolation rate of 51%. Comparison of all possible combinations of the eight media showed that the highest rate of isolation of H. pylori was 100% (114 of 114) with EYE-MCHOC, followed by 96.5% (110 of 114) when EYE-TSA was used. Conversely, it was found that none of the media used alone yielded a 100% rate of recovery (the maximum recovery rate was 95%, which was achieved with EYE). These results indicate that the association of EYE and MCHOC yielded the maximum recovery of H. pylori from gastric biopsy specimens. Therefore, the use of selective and nonselective media in parallel offers optimal recovery rates with only a slight increase in costs.

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