A pitfall of H. pylori blood serology is that it cannot distinguish past infection from current infection.

A pitfall of H. pylori blood serology is that it cannot distinguish past infection from current infection.

• A. It can distinguish past from current infections
• B. It cannot distinguish past from current infections
• C. It is unaffected by prior antibiotic use
• D. It measures bacterial load directly

Answer: (B)

H. pylori blood serology detects antibodies against the bacterium, not the bacteria itself. Antibodies can remain in the blood for months to years after an infection has been cleared, so a positive serology test may reflect a past infection rather than an active one. Because of this, serology cannot reliably distinguish current infection from past exposure. To confirm active infection, tests that detect current presence of the organism are used instead, such as the urea breath test or stool antigen test, or direct methods like endoscopy with biopsy for histology or culture. Serology is useful for initial screening in some contexts but not for confirming eradication or active disease. This option states the inherent limitation accurately: serology cannot differentiate past from current infection. The other statements don’t describe this pitfall: serology does not measure bacterial load directly, and while prior antibiotics don’t typically change the presence of antibodies, they can clear the infection without removing antibodies, which is exactly why serology isn’t reliable for judging current status.

H. pylori blood serology detects antibodies against the bacterium, not the bacteria itself. Antibodies can remain in the blood for months to years after an infection has been cleared, so a positive serology test may reflect a past infection rather than an active one. Because of this, serology cannot reliably distinguish current infection from past exposure.

To confirm active infection, tests that detect current presence of the organism are used instead, such as the urea breath test or stool antigen test, or direct methods like endoscopy with biopsy for histology or culture. Serology is useful for initial screening in some contexts but not for confirming eradication or active disease.

This option states the inherent limitation accurately: serology cannot differentiate past from current infection. The other statements don’t describe this pitfall: serology does not measure bacterial load directly, and while prior antibiotics don’t typically change the presence of antibodies, they can clear the infection without removing antibodies, which is exactly why serology isn’t reliable for judging current status.