H. Pylori

What is the classification of Helicobacter pylori?

Gram-negative spirochete (spiral-shaped).

What is the primary reservoir for H. pylori?

The oral cavity.

What are the the three transmission routes for H. pylori.

Oral-Oral (kissing), gastro-oral (vomit), and fecal-oral (contaminated water).

Why is H. pylori considered a known carcinogen?

Chronic inflammation leads to DNA damage and gastric carcinoma (stomach cancer).

What do dark or tarry stools indicate in a patient with gastric issues?

The presence of blood from the gastrointestinal tract.

What is the chemical reaction catalyzed by H. pylori urease.

Urea → NH₃ + CO₂

How does ammonia (NH₃) protect H. pylori in the stomach?

It creates a localized cloud of higher pH to neutralize stomach acid.

In the stomach, H. pylori moves from the acidic lumen toward the neutral pH of the ____.

Epithelial cell surface (mucosa)

What is the virulence factor of H. pylori?

CagA (cytotoxin-associated gene A) = an oncoprotein that alters host cell signaling and increases the risk of gastric center.

What host enzyme phosphorylates CagA to activate its cancer-promoting signaling?

SRC kinases.

What is the mechanism of the VacA (Vacuolating cytotoxin)?

A pore-forming toxin that creates vacuoles (holes) in host cells and disrupts the stomach lining.

What is the role of neutrophil activating protein (NAP) in H. pylori infection?

It activates neutrophils, which causes mucosal damage through inflammation.

How does the H. pylori LPS O antigen induce autoimmunity?

It mimics host Lewis X and Y antigens, causing the immune system to attack host cells.

What is the mechanism of the urea breath test?

The patient ingests urea, if urease is present, CO₂ is detected in the exhaled breath.

Which H. pylori test is used to confirm that an infection has been cleared post-treatment?

Stool antigen test.

What are the limitations of blood antibody tests for H. pylori?

They can’t distinguish between a current infection and a past, cleared infection.

What is STI prevalence?

The total estimated number of existing and new infections in a given time period.

What is STI Incidence?

The estimated number of new infections diagnosed or undiagnosed in a given period.

What are the four curable STIs identified by the CDC?

Syphilis, gonorrhea, chlamydia, and trichomoniasis.

What are the four incurable (viral) STIs identified by the CDC?

Hepatitis B (HBV), herpes simplex virus (HSV), HIV, and human papillomavirus (HPV)

What are the common symptoms of genital herpes (HSV)?

Itchy or painful fluid-filled blisters on the genitals or buttocks.

What are the consequences of untreated chlamydia or gonorrhea in women?

Pelvic inflammatory disease (PID), which can lead to infertility.

What are the symptoms of Hepatitis B (HBV) infection?

Jaundice (yellowing of skin/eyes)

What medication is used to prevent HIV infection in high-risk individuals?

PrEP (Pre-Exposure Prophylaxis).

What are the common complications of Human Papillomavirus (HPV)?

Genital warts and various cancers (cervical, penile, oral, or anal).

What are the complications of untreated late-stage syphilis?

Heart disease, nervous system problems, paralysis, or blindness.

What are the characteristic symptom of Trichomoniasis in women?

Genital discharge with a foul odor and itching/burning.

What is a molecular mimicry?

When bacterial antigens look like host antigens, causing the immune system to attack the body’s own tissues.

What STI has the highest prevalence (total cases) and highest annual incidence (new cases) in the US?

Human Papillomavirus (HPV)

How can H. pylori transmission be reduced in developing nations?

Improving water quality to prevent fecal-oral transmission.

What is the standard treatment for bacterial STIs like syphilis?

Prescription antibiotics.

Why must the full course of antibiotics be finished for H. pylori?

The patient remains contagious until the entire treatment is completed.