Add bacterial suspensions to 15-milliliter polystyrene tubes, and use a plastic loop to transfer one 10- to 20-microliter droplet from each culture onto individual glass microscope slides. Then, assess the viability and motility of the bacteria under phase contrast microscopy at a 100 times magnification.
Only use the H. pylori inocula if the majority of the bacteria have a bacillary shape. H. felis inocula should primarily contain helical-shaped bacteria, and load the inocula into individual disposable 1-milliliter syringes. Equip each syringe with a 23-gauge needle and use plastic paraffin film to attach a disposable polyethylene catheter to each needle.
Next, manually restrain a 6- to 8-week-old specific pathogen-free and Helicobacter-free mouse by the scruff of the neck and tail and insert one catheter into the center of the open jaw. Guide the catheter in a caudal direction toward the esophagus, extending the neck of the mouse to allow ease of access to the stomach through the esophagus and away from the trachea until most or all of the catheter is no longer visible and a resistance is felt. Then, deliver at least 1 x 105 bacteria to ensure an optimal colonization in disease pathology.
