A 3-year-old alcoholic, homeless man presents with fever and cachexia. He has clubbing of the fingers, halitosis, missing teeth, and numerous dental caries. Chest examination shows increased fremitus, dullness to percussion, and tubular breath sounds in the right lower lung. Sputum culture yields purulence with gram-positive cocci in chains and gram-negative bacilli. A chest X-ray shows a cavitary lesion in the right lower lobe with surrounding infiltrate. Sputum is most likely to grow which of the following?

A 3-year-old alcoholic, homeless man presents with fever and cachexia. He has clubbing of the fingers, halitosis, missing teeth, and numerous dental caries. Chest examination shows increased fremitus, dullness to percussion, and tubular breath sounds in the right lower lung. Sputum culture yields purulence with gram-positive cocci in chains and gram-negative bacilli. A chest X-ray shows a cavitary lesion in the right lower lobe with surrounding infiltrate. Sputum is most likely to grow which of the following?

• A. Normal oral flora
• B. Pseudomonas aeruginosa
• C. Staphylococcus aureus
• D. Klebsiella pneumoniae

Answer: (A)

Infection from aspirated oropharyngeal contents often leads to a lung abscess, especially in someone with poor dentition and heavy oral bacterial load. The organisms causing these infections are typically the normal inhabitants of the mouth (anaerobes and mixed oral flora, including streptococci in chains and various gram-negative rods). When a sputum sample is contaminated with oral secretions, the culture often grows organisms that are part of normal oral flora rather than a single distinct pathogen. The clinical clues—halitosis, dental caries, and cavitation with surrounding infiltrate—fit aspiration of oral flora. The mixed Gram-positive cocci in chains and Gram-negative bacilli described in the culture align with these normal oral bacteria, not a specific opportunistic pathogen. Therefore, the sputum is most likely to grow normal oral flora.

Infection from aspirated oropharyngeal contents often leads to a lung abscess, especially in someone with poor dentition and heavy oral bacterial load. The organisms causing these infections are typically the normal inhabitants of the mouth (anaerobes and mixed oral flora, including streptococci in chains and various gram-negative rods). When a sputum sample is contaminated with oral secretions, the culture often grows organisms that are part of normal oral flora rather than a single distinct pathogen.

The clinical clues—halitosis, dental caries, and cavitation with surrounding infiltrate—fit aspiration of oral flora. The mixed Gram-positive cocci in chains and Gram-negative bacilli described in the culture align with these normal oral bacteria, not a specific opportunistic pathogen. Therefore, the sputum is most likely to grow normal oral flora.