Which factor most contributes to recurrent urinary tract infections (UTIs) in older men?

A. Western European is incorrect because sickle cell anemia is rare among individuals of Western European descent. While carriers exist, the prevalence is much lower than in populations of African ancestry.

B. Native American is incorrect because sickle cell anemia is uncommon in Native American populations. Other hemoglobinopathies, like thalassemia, may be more prevalent in specific indigenous groups.

C. African is correct because sickle cell anemia is caused by a recessive mutation in the HBB gene, which affects the beta chain of hemoglobin. This mutation leads to the production of abnormal hemoglobin S, causing red blood cells to adopt a sickle shape under low oxygen conditions. Sickle-shaped cells are rigid, sticky, and prone to hemolysis, leading to anemia, vaso-occlusive crises, and organ damage. The gene is more commonly found in individuals of African descent, as heterozygosity (carriers) provides some protection against malaria, which historically explains the high prevalence in Africa.

D. Asian is incorrect because sickle cell anemia is relatively rare in Asian populations. Other hemoglobin disorders, such as thalassemia, are more common in Southeast Asian and Mediterranean populations.

A. Tuberculosis is correct because Mycobacterium tuberculosis infection leads to granulomatous inflammation in the lungs. Over time, this can cause caseous necrosis, resulting in cavitation, where the lung tissue breaks down and forms large open spaces (cavities). These cavities can erode into pulmonary blood vessels, potentially leading to hemoptysis (coughing up blood). The destruction of lung tissue impairs gas exchange and can facilitate spread of the infection. Cavitation is a hallmark of active, progressive pulmonary TB, particularly in adults.

B. Bronchiolitis is incorrect because it involves inflammation of the small bronchioles, usually caused by viral infections (e.g., RSV). It primarily affects airway obstruction in infants and does not cause cavitation or necrosis of lung tissue.

C. Chronic bronchitis is incorrect because it is a chronic inflammatory condition of the bronchi, characterized by persistent cough and mucus production for at least three months per year. While it causes airway narrowing and increased susceptibility to infections, it does not produce necrosis or cavitation.

D. Asthma is incorrect because asthma is a chronic inflammatory disorder of the airways with bronchospasm, hyperreactivity, and mucus production. Asthma involves reversible airway obstruction and does not cause lung tissue necrosis or cavitation.