A 63-year-old alcoholic presents complaining of chest pain, fever, shaking chills, cough, and myalgia. She was very cold two nights ago and says she has felt "poorly" ever since. Her cough is producing rust-colored, odorless, mucoid sputum. Her temperature on admission is 40°C. Her white blood cell count is 16,000 cells/mm3 and is predominantly neutrophils with an overall left shift. An $\alpha$-hemolytic, lancet-shaped, Gram-positive diplococcus is isolated on blood agar. What is the most likely causative agent?

Question

Quizplus · Accepted Answer

Streptococcus pneumoniae is the most common causative agent of pneumonia in alcoholics. Klebsiella pneumoniae is less common but even more deadly because of the high incidence of abscesses. (Almost all of the patients who have pneumonia caused by K. pneumoniae suffer from chronic lung disease or alcoholism.) If foul-smelling sputum had been present, then anaerobes would most likely be involved. Legionella and Klebsiella are both Gram-negative rods. Neisseria meningitidis is a Gram-negative diplococcus. Neither Legionella nor Mycoplasma would have grown on blood agar.

A 63-Year-Old Alcoholic Presents Complaining of Chest Pain, Fever, Shaking α\alphaα

A 63-Year-Old Alcoholic Presents Complaining of Chest Pain, Fever, Shaking $\alpha$