BACTERICIDAL AND MORPHOLOGICAL EFFECTS OF AMOXICILLIN ON HELICOBACTER-PYLORI

The growth kinetics of Helicobacter pylori after it has been exposed to amoxicillin have been investigated in conjunction with studies of cell morphology. A potent bactericidal effect was observed at concentrations 10-fold higher than the MIC, but this was accompanied by an increase in the residual numbers of coccoid forms observed. In the presence of 10 mu g of amoxicillin per ml, these forms could be detected as rapidly as 6 h after exposure to the antibiotic Although the clinical relevance of coccoid forms remains unknown, such forms should be considered when potential anti-Helicobacter agents are tested in vitro.