Coccoid forms of Helicobacter pylori.

To the Editor-Eaton et al. [1] recently described experiments with coccoid Helicobacter pylori in gnotobiotic piglets. This interesting study examined the colonization and the reversion from coccoid to bacillary H pylori within 2 weeks of inoculation. Piglets colonized with bacillary H pylori had more severe gastritis 2 weeks after inoculation than did those sacrificed 1 week after inoculation. The coccoid H pylori did not colonize stomachs and did not lead to histopathologic changes. Our experience with coccoid H pylori inoculated intragastrically in a similar experimental design in BALB/c mice differed [2]. Concentrated coccoid (A 550 = 5 McFarland units) H pylori cultures (20 days of incubation), not culturable in vitro (0 cfu/mL), showed coloni-zation and produced gastric alteration with a peak 4 weeks after inoculation. In our studies, the histologic changes obtained with fresh coccoid H pylori were lower than those in mice infected with the same strains in bacillary morphology, probably due to partial reversion of the coccoid bacteria and therefore smaller concentrations of strains colonizing the mouse stomach. Others have shown coccoid degenerate forms and coccoid whole H pylori [3]; moreover, in Vibrio-like strains, reversion from dormant coccoid to bacillary forms has been demonstrated [4]. The interest in the "dormant" coccoid H pylori is related to the clinical Reply To the Editor-We would like to thank Dr. Cellini for the opportunity to apologize for failing to cite this author's work in our original publication. This was an important oversight, and we regret the error. Like Cellini [1], we were surprised by the reported colonization of BALB/c mice by coccoid forms of Helicobacter pylori. This is especially interesting given the acknowledged low and variable colonization of H pylori in mice [2-4] compared with piglets [5, 6], puppies [7], and possibly other mammals [8, 9]. Cellini suggests that one explanation for the difference between significance of these forms. In fact, this morphology can be generated in vitro with prolonged incubation and also with subinhibiting concentrations of drugs. Therefore, we can hypothesize that with incomplete clearing of the organism, when therapy in H pylori-positive patients is suspended, "stressed" H pylori forms can be generated [5], and this morphology may account for the wide number of relapses. I suggest that the study of the significance of coccoid H pylori [6] and, in particular, the quantification of whole strains in this morphology are very important to determine the organism's mode of transmission. Therefore, …