Patient with active tuberculosis

Correct answer: C. Reschedule until the patient is no longer infectious

• A. An N95 alone is inadequate for a routine dental operatory, which lacks the negative-pressure airborne infection isolation required.
• B. Refusing care permanently would be discriminatory; care is postponed, not denied.
• C. Correct. ELECTIVE dental treatment is DEFERRED for a patient with ACTIVE, infectious tuberculosis. The patient is rescheduled after the treating physician confirms they are no longer infectious — typically after adequate therapy with clinical improvement and three consecutive negative sputum smears.
• D. Standard precautions are insufficient. TB is transmitted by AIRBORNE droplet nuclei that remain suspended for hours, and dental procedures generate aerosols.

Correct answer: D. Treat in an isolated room with appropriate airborne-infection controls

• A. Standard precautions do not protect against airborne transmission.
• B. Scheduling at the end of the day is a strategy for CONTACT and droplet precautions; it does not address airborne nuclei that persist in the air.
• C. The emergency department is not equipped for definitive dental care, and referral without the appropriate airborne setting simply moves the exposure risk.
• D. Correct. When treatment CANNOT be deferred, it is provided in a facility with AIRBORNE INFECTION ISOLATION — a negative-pressure room with appropriate air exchanges and HEPA filtration or UV germicidal irradiation, with all staff wearing fit-tested N95 or higher respirators. This is typically a hospital setting rather than a general dental practice.

Correct answer: D. Hepatitis

• A. Cardiac arrhythmia is not a recognised principal adverse effect.
• B. OPTIC NEURITIS with red-green colour vision loss is the hallmark toxicity of ETHAMBUTOL, a different first-line anti-TB drug.
• C. Renal impairment is not the characteristic isoniazid toxicity.
• D. Correct. ISONIAZID is HEPATOTOXIC — drug-induced hepatitis is its major adverse effect, and risk increases with age and with concurrent alcohol use. It also causes PERIPHERAL NEUROPATHY by interfering with pyridoxine (vitamin B6) metabolism, which is why B6 is co-prescribed.

Note: First-line TB drugs and their signature toxicities: Isoniazid — hepatitis and peripheral neuropathy; Rifampin — hepatotoxicity and ORANGE-RED discoloration of body fluids; Pyrazinamide — hepatotoxicity and hyperuricemia; Ethambutol — optic neuritis. DENTAL RELEVANCE: hepatic impairment affects the metabolism of local anaesthetics and analgesics, so avoid additional hepatotoxins such as acetaminophen at high doses.