Answer:
Microbes can be beneficial and at the same time harmful for our body systems in many different ways for example in the case of helicobacter pylori they can cause ulcers and stomach cancer, but in the other hand loss of this bacteria may be correlated with an increase in GERD, and is also correlated with an increase of esophageal cancer even with obesity (because of the hormone called ghrelin which decrease when we are full after eating sending the signal to our brains that says its time to stop, when helicobacter is not present this hormone can be produced even when we are full not sending the stop signal to our brains resulting on obesity)
Step-by-step explanation:
Another example of good bacteria is the one that colonizes the vagina, they maintain acidic environment in the vagina that prevents the growth of other microorganisms that may cause disease.
An example of good bacteria that can harm us even when they are helpful for our body is the bacteria that lives in our skin, for example if we cut ourselves that bacteria could get inside our body triggering infection, symptoms of an infection may include pain, swelling, redness and fever.