A 40-year-old man develops a cough that is nonproductive and goes to see his family doctor. He says that he has been feeling "lousy" and has bronchitis, sinusitis, and a sore throat. The doctor orders an x-ray that does not show consolidation, but rather a patchy infiltrate in his upper right lung. The man denies taking any new pets or animals recently into his house. A Gram-stain of the sputum specimen shows a few Gram-negative rods that do not stain very well. Samples sent to the clinical laboratory do not grow on normal laboratory media (e.g., blood agar), but do grow i n monolayer cells in tissue culture. What bacterium is most likely to be the cause of this man's infection?
Chlamydophila pneumoniae produces pharyngitis, bronchitis, sinusitis, and pneumonia in humans. The lungs will show a patchy infiltrate upon x-ray. It is a Gram-negative bacterium that does not stain well upon Gram-stain. It will not grow in vitro (e.g., on blood agar), but will grow in tissue culture cells because it is a strict intracellular bacterial pathogen. Streptococcus pneumoniae and Mycoplasma pneumoniae will both cause pneumonia, but they will both grow in vitro and are not obligate intracellular bacterial pathogens. Both C. trachomatis and C. psittaci are obligate intracellular bacterial pathogens. C. trachomatis causes ocular and genital infections, so is therefore incorrect. C. psittaci can cause pneumonia but is also incorrect because the man has not recently obtained any new birds into his household.
Chlamydia trachomatis
Chlamydophila psittaci
Chlamydophila pneumoniae
Mycoplasma pneumoniae
Bacteria