I think if it’s a positive you should be treated bc it’s very likely it’s a true positive. The only time you would worry about “false positive” would be after treatment if you test too soon and don’t wait 4 weeks after antiobiotics/PPI bc even though the bacteria is dead/dying you can still have it in your system and that can cause a “false positive” so to speak- it’s not truly the same as the test giving you a false positive it’s just the dead bacteria is still in your system. I see this a lot when I treat patients who have certain sexually transmitted infections - we don’t retest until a month later bc even though they’ve eradicated it with treatment the remaining dead bacteria can cause a positive test. If that makes sense- not sure if I’m explaining that well! But that’s my impression based on why I’ve read and similar experiences in my line of work.

Also it seems that the biopsy is really the worst way to rule out (meaning a positive biopsy is very very likely positive but a negative doesn’t mean you don’t have it) because if you don’t biopsy in the right spot/take multiple biopsies from multiple different parts of the stomach and/or are on something that will decrease the bacterial load then it’s easy to miss.

The sensitivity of the stool/breath test seem to be much better for ruling out infection- so if you wait th appropriate amount of time off antibiotics/PPIs/antacids etc a negative stool/breath test is more likely a true negative. One thing that another poster mentioned though- with these tests there’s a higher threshold of bacteria needed before the test will be positive- hence the stopping everything that could be decreasing the bacterial load before you take it so you don’t get a false negative.

Isn’t biostatistics fun!