It is quite possible.
IIRC, some types of pneumonia, stomach ulcers, and heart murmurs have been said to be caused by certain kinds of bacteria.
One of the treatments for stomach ulcers is high doses of the bismuth in products like Pepto Bismol.
Also, Rheumatoid Arthritis has been linked to gut bacteria. Some doctors prescribe antibiotics for RA, and in some cases it works.
Peptobismol only makes helicobacter pylorii vulnerable. It takes amoxycillin antibiotic coadministered to kill them. Either medicine alone will not due the trick.
(Don't know what the effective dosage is. It's if/when I've had to take amoxycillin to conquer an abcessed tooth that I always take some Peptobismol at the same time, a course of treatment of about 2 weeks, just in case. It is helpful to know that the sulfonophane in broccoli also can eradicate the h. pylori, which can caise gastritis and stomach cancer.)