Letter to the Editor Helicobacter pylori in oral aphthous ulcers Jasminka Pavelic ´ 1 Koraljka Gall-Tros ˘elj 1 Igor Jurak 1 Marinka Mravak-Stipetic ´ 2 1 Laboratory of Molecular Oncology, Division of Molecular Medicine, Rud - er Bos ˘kovic ´ Institute, Bijenic ˘ka c. 54, 10000 Zagreb, Croatia 2 Department of Oral Medicine, School of Dentistry, University of Zagreb, Gundulic ´eva 5, 10000 Zagreb, Croatia Correspondence to: Dr. C. Birek Department of Oral Biology, Faculty of Dentistry, University of Manitoba, 780 Bannatye Avenue, Winnipeg, Manitoba, R3E 0W2, Canada Accepted for publication May 6, 2000 Copyright C Munksgaard 2000 J Oral Pathol Med . ISSN 0904-2512 Printed in Denmark . All rights reserved 523 J Oral Pathol Med 2000: 29: 523–5 Dear Sir, We read with interest the paper written by Birek et al. (1) regarding the role of Helicobacter pylori in aphthous ulcers. We would like to express some of our concerns and to share our newest results. In the Division of Molecular Medicine, Rudjer Bos ˘kovic ´ Institute, Zagreb, Croatia, routine diagnoses of pathogens present in a variety of oral cavity lesions have been performed in collaboration with the Department of Oral Medicine, School of Dentistry, University of Zagreb. A study was initiated in 1996, to detect Helicobacter pylori. Two years later, the study was extended to detect five more patho- gens. Eikenella corrodens, Porphyromonas gingivalis, Actinobacillus actinomycetemcommitans, Bacterioides forsythus and Prevotella in- termedia (in preparation for publication). For all the pathogens, de- tection is based on DNA isolation (phenol/chloroform procedure) and, subsequently, either nested polymerase chain reaction (PCR) or RFLP analysis. At the beginning of 1988, we published in your journal (2) data on the presence of H. pylori in various oral lesions. One hundred and sixty-one consecutive patients participated in the study. For some patients, the samples were collected from two different topo- graphic oral cavity sites, so that a total of 181 specimens were tested. Of these patients, 32 were diagnosed as suffering from recur- rent aphthus ulcers, while most of the others were diagnosed as having oral lichen planus, benign migratory glossitis, burning mouth syndrome and glossopyrosis. Altogether, the specimens were collected from seven different topographic sites. Of 161 patients, only 21 (13%) were positive for H. pylori urease A gene after nested PCR; among them, only four patients suffered from aphthous ulcer. None of the samples exhibited a visible DNA band after the first round of amplification. The percentage of H. pylori-positive patients with ulcerous and non-ulcerous disease was the same. No corre- lation was found between H. pylori status and patient’s age and