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Filamentous organisms have been reported in brushings and biopsies from both benign and malignant gastric ulcers,1,2 but these have not been characterised and their importance is unknown. In a preliminary study of tissue samples obtained at laparotomy from malignant gastric ulcers we cultured Lactobacillus spp, which are recognised commensals in the upper gastrointestinal tract,3 but not normally present in the stomach.
In view of the previous culture of Lactobacilli spp in surgically excised gastric tumours, we prospectively sought evidence of Lactobacilli spp infection of benign and malignant gastric ulcers in patients attending for gastroscopy.
Gastric mucosal biopsies were obtained from normal mucosa, erosions, and from benign and malignant ulcers in patients undergoing routine gastroscopy in our unit. The endoscopic biopsies were immediately placed into 5 ml of semisolid De Man, Rogosa, Sharpe (MRS) culture medium for transportation to the laboratory. Biopsies were then plated on to the following: (1) 5% blood agar and MRS agar incubated in CO2 at 37°C; and (2) neomycin agar and MRS agar incubated anaerobically at 37°C. After incubation for 48 hours, any probable Lactobacillus spp were subcultured to blood agar and Gram staining was performed. The cultures were re-checked at five days for slow growing strains. All Gram positive bacilli were stored at −70°C for later identification by catalase reaction and a profile using a gallery scheme (API 50 CHL) and fermentation of 49 carbohydrates.
In total, 39 patients were studied. Histology of the gastric biopsies revealed: adenocarcinoma (n = 9), gastric lymphoma (n = 2), benign gastric ulcer (n = 8), gastric erosions (n = 11), and normal mucosa (n = 9). All strains of Lactobacillus spp had grown at 48 hours.
Ten of 11 malignant and six of eight benign gastric ulcers grew Lactobacillus spp. In addition, Lactobacillus spp were cultured in four of 11 gastric erosions but all the normal specimens were negative for culture. Some specimens yielded more than one species. Some lactobacilli could not be speciated. Table 1 shows the numbers of specimens with each histological diagnosis that were culture positive for the individual species of lactobacillus.
These data demonstrate that Lactobacillus spp colonise areas of both malignant and benign gastric ulceration but not normal mucosa. It is probable, but not confirmed, that these are the filamentous organisms previously described in similar samples. Although we cannot exclude a role for these bacteria in the aetiology of gastric ulceration, it seems most likely that they opportunistically colonise the necrotic tissue in areas of ulceration of whatever cause. Clarification of the mechanisms that underlie this phenomenon might provide a means to target gastric malignancy both for diagnosis and treatment. Additional work is needed to explore the relation between gastric ulceration and Lactobacillus spp.
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