Coccoid Helicobacter pylori Can Directly Adhere and Invade in Agminated Formation to Human Gastric Epithelial Cells

Helicobacter pylori (H. pylori) can infect into the epithelial cell to cause benign or malignant disorders. Under stressful environment, a spiral form of H. pylori is transformed into a coccoid form. The infectivity of the coccoid form is still controversial. Since spiral forms are transformed into two types of coccoid forms via different mechanisms, the infectivity of the two types of coccoid forms into human gastric epithelial cell was examined. A laboratory and a clinical strain of H. pylori were cultured in liquid medium under different conditions to produce the two types of coccoid forms. These coccoid H. pyloris were then co-cultured with human derived gastric epithelial cell, MKN-28. Adhesion and penetration of bacteria into MKN-28 cells were monitored by scanning-, standard transmissionand immunotransmission-electron microscopy (SEM, TEM and ITEM). We observed that both coccoid forms were able to adhere onto the surface of MKN-28 cells in agminated formation and also penetrated into the gastric epithelial cells besides the spiral form of H. pylori. Coccoid H. pylori is not a passive entity but can actively infect the human gastric epithelial cell.