Which microorganism is most commonly associated with gastritis?

Correct Answer: C

Rationale: ### **Comprehensive Rationale for the Correct Answer (C: *H. pylori*) and Incorrect Choices (A, B, D)** #### **Why *H. pylori* (Option C) is Correct** **1. Strong Epidemiological Link** *Helicobacter pylori* (*H. pylori*) is a gram-negative, spiral-shaped bacterium that colonizes the gastric mucosa and is the **most common cause of chronic gastritis worldwide**. It is estimated to infect over **50% of the global population**, with higher prevalence in developing countries. **2. Pathogenic Mechanism** - *H. pylori* produces **urease**, an enzyme that neutralizes stomach acid by converting urea to ammonia, allowing the bacterium to survive in the harsh acidic environment. - It damages the gastric epithelium by **inducing inflammation** (via cytokines like IL-8) and disrupting the mucosal barrier, leading to gastritis. - It is also a **major risk factor** for peptic ulcers, gastric adenocarcinoma, and MALT lymphoma. **3. Diagnostic Evidence** - Gold-standard tests for *H. pylori* include **urea breath tests**, stool antigen tests, and endoscopic biopsy with histology showing **chronic active gastritis**. - Eradication of *H. pylori* with antibiotics (e.g., clarithromycin, amoxicillin, and proton pump inhibitors) **resolves gastritis** in most cases, further confirming its causative role. --- #### **Why the Other Options Are Incorrect** **A: *Syphilis* (Incorrect)** - Syphilis is caused by the spirochete *Treponema pallidum*, which primarily affects **genital, neurological, and cardiovascular systems**, not the stomach. - While **tertiary syphilis** can cause **gummatous lesions** in rare cases, these are **not typical for gastritis**. - Gastritis caused by syphilis is **extremely rare** and would present with systemic symptoms (e.g., rash, neurosyphilis), not isolated gastric inflammation. **B: *Cytomegalovirus* (CMV) (Incorrect)** - CMV is a herpesvirus that can cause **opportunistic infections**, particularly in **immunocompromised patients** (e.g., HIV/AIDS, transplant recipients). - While CMV can lead to **gastritis or ulcers**, it is **much less common** than *H. pylori* and usually requires immunosuppression. - Diagnosis involves **viral PCR or biopsy showing intranuclear inclusion bodies**, not standard gastritis testing. **D: *Mycobacterium* (Incorrect)** - *Mycobacterium tuberculosis* and other mycobacteria primarily cause **pulmonary infections (TB) or systemic disease**, not gastritis. - Gastric TB is **exceptionally rare** and usually occurs secondary to pulmonary TB, presenting with **ulcerative lesions**, not typical chronic gastritis. - *Mycobacterium avium complex* (MAC) can infect the GI tract in **AIDS patients**, but this is **not a common cause of gastritis** in the general population. --- ### **Conclusion** The **overwhelming evidence** links *H. pylori* as the **primary and most frequent cause of gastritis**, supported by its **pathogenicity, global prevalence, and clinical diagnostic criteria**. The other pathogens are either **rare, opportunistic, or associated with different disease presentations**, making them incorrect choices. **Final Answer: C (*H. pylori*)** is correct.

Correct Answer: A

Rationale: Hepatitis A is the correct answer because it is transmitted via the fecal-oral route, often through contaminated food or water. Hepatitis B is transmitted through exposure to infectious blood, semen, and other body fluids, not through the fecal-oral route. Hepatitis C is transmitted through blood-to-blood contact, not via the fecal-oral route. Hepatitis D occurs only in individuals infected with Hepatitis B. Therefore, the correct choice for the type of hepatitis transmitted via the fecal-oral route is Hepatitis A.

Correct Answer: C

Rationale: Acinar cells are responsible for creating exocrine secretions, such as enzymes and digestive juices. Alpha cells are found in the pancreas and are responsible for producing glucagon, beta cells produce insulin, and plasma cells are a type of white blood cell involved in immune responses. Therefore, the correct answer is acinar cells, as they specifically produce exocrine secretions.

Correct Answer: A

Rationale: Active transport is the correct answer as it accurately describes the process involved in the sodium-potassium pump. The pump utilizes energy to move ions against their concentration gradient, maintaining cellular concentrations. Diffusion (choice B) is a passive process where substances move from an area of higher concentration to lower concentration. Filtration (choice C) involves the movement of solutes based on pressure gradients. Osmosis (choice D) is the movement of water across a semipermeable membrane.

Correct Answer: C.

Rationale: In Parkinson's disease, the client's difficulty in performing voluntary movements is termed dyskinesia. Dyskinesia refers to the impairment of the ability to execute voluntary muscle movements. Akinesia, on the other hand, refers to the absence or lack of voluntary movement. Chorea is characterized by involuntary, rapid, irregular movements. Dystonia involves sustained muscle contractions resulting in abnormal postures or twisting movements. Therefore, dyskinesia is the specific term used for the described difficulty in Parkinson's disease.