**Question:** All of the following are true regarding congenital tuberculosis except

A. Tuberculosis can be transmitted from an infected mother to the fetus during pregnancy or childbirth.
B. Mycobacterium tuberculosis, the causative agent of tuberculosis, can be transmitted through contact with tuberculosis-infected sputum or body fluids.
C. Congenital tuberculosis is rare in developed countries due to widespread vaccination with Bacille Calmette-Guérin (BCG) vaccine.
D. Diagnosis of congenital tuberculosis is always confirmed by isolating Mycobacterium tuberculosis from the infected infant's blood, tissue, or body fluid samples.

**Correct Answer:** D. Diagnosis of congenital tuberculosis is always confirmed by isolating Mycobacterium tuberculosis from the infected infant's blood, tissue, or body fluid samples.

**Core Concept:** Congenital tuberculosis is a rare but severe form of tuberculosis that occurs when the mother passes the infection to the fetus during pregnancy or childbirth.

**Why the Correct Answer is Right:** The correct answer is right because isolating Mycobacterium tuberculosis from the infected infant's blood, tissue, or body fluid samples is the gold standard for confirming the diagnosis of congenital tuberculosis. This is because the infection is typically transmitted before birth, and the infants may not show typical symptoms or radiographic findings until later in life.

Culture or molecular tests on the infant's samples can isolate the causative agent, confirming the diagnosis.

**Why Each Wrong Option is Incorrect:**

A. While tuberculosis can be transmitted during pregnancy and childbirth, option A is incorrect because it does not address the specific challenge of diagnosing congenital tuberculosis due to the infection being acquired before birth.

B. Although Mycobacterium tuberculosis can be transmitted through contact with tuberculosis-infected sputum or body fluids, option B is incorrect because it does not highlight the unique diagnostic challenges faced in congenital tuberculosis cases.

C. While congenital tuberculosis is indeed rare in developed countries due to widespread vaccination with BCG, option C is incorrect as it does not address the diagnostic aspect of the question and focuses on the epidemiology instead.

D. The gold standard for confirming congenital tuberculosis is isolating Mycobacterium tuberculosis from the infant's samples; however, the answer does not specify that culture or molecular tests are required for diagnosis.

**Clinical Pearl:** Diagnosing congenital tuberculosis can be challenging due to the infection being acquired before birth, which may result in delayed presentation or lack of typical symptoms and radiographic findings. The correct diagnosis requires isolating Mycobacterium tuberculosis from the infant's samples using culture or molecular tests.