Your right it is clarithromycin. Well the macrolide decrease bacterial protein synthesis by binding to the bacterial ribosome and is moslty bacteriostatic. While the beta lactam inhibit peptidoglycan synthesis and is moslty bacteroicidal. I read in some studies that this combo can be antagonistic because the bacteriostatic action of the macrolide will decrease the bacteriocidal action of the beta lactam. I understand why it is used for community aquired pnuemonia, which is to cover the typical and atypical pathogens. But why have this combo for H. pylori?