Which of the following is an occasional cause of respiratory tract infections and is rapidly urea positive?

• A. Bordetella bronchiseptica
• B. Brucella abortus
• C. Campylobacter fetus
• D. Escherichia coli

Answer: (A)

Bacteria that cause respiratory infections in humans and also rapidly produce urease can be identified by how quickly they hydrolyze urea to ammonia, raising the pH of a urease-containing medium. Among these options, Bordetella bronchiseptica is known to cause occasional respiratory infections in humans, especially in those with underlying conditions, and it is rapidly urease positive. This combination explains why it’s the best fit for the described scenario.

Brucella abortus mainly causes brucellosis and is not a typical respiratory pathogen in humans; Campylobacter fetus is associated with animal abortion and gastroenteritis rather than respiratory disease; Escherichia coli is primarily an enteric pathogen and does not characteristically show rapid urease positivity.