Lung Abscess - Case Based Study

A 50-year-old male who is a heavy drinker with a history of squamous cell carcinoma of the neck presents to your office complaining of abdominal pain. He has been coughing and expectorating bloody sputum and notes a low-grade fever, chills, and mild dyspnea starting about 1 week ago. He denies nausea, emesis, and chest pain. His squamous cell carcinoma was treated with external beam radiation several years ago.
Examination reveals an afebrile male in mild distress. His vital signs are normal, and his lungs sound clear. The abdominal exam reveals only mild epigastric tenderness
The chest x-ray is shown below:

Findings (  cavitary lesion right upper lobe)

Q 1. Considering this 50-year-old with a cough what will be your next step: 
A) This gentleman will need the ICU.”
B)  This gentleman will need a respiratory isolation room.”
C)  Send this gentleman home with metronidazole.”
D) Work up this gentleman as an outpatient.”

Answer And Discussion

The correct answer is “B.” This gentleman will need a respiratory isolation room.”

Because he is expectorating bloody sputum and has a cavitary lesion on chest x-ray (right upper lobe), this patient should be admitted to a respiratory isolation room until tuberculosis is ruled
out. He will need further evaluation and possibly intravenous antibiotic therapy, both of which may be accomplished during his hospitalization.
“A” is incorrect. There is no need to send this patient to the ICU based on his current picture. “C” is also incorrect. Metronidazole alone is not an appropriate therapy for this patient even if this is bacterial (see below).


Q 2.  What is the best next step in the diagnosis of this process?
A) Bronchoscopy.
B) Sputum cultures
C) Blood cultures.
D) Chest CT.
E) Open lung biopsy.

Answer And Discussion
The correct answer is “D.” Chest CT.

The chest x-ray demonstrates a cavitary lesion in the right upper lobe. Chest CT is warranted for further characterization of the lesion. From history, exam, and chest x-ray, it is not possible to determine whether the lesion is an abscess or a malignant process. An indolent course with lowgrade fever is characteristic of lung abscess. However, the preexisting squamous cell carcinoma has potential to have spread to the lungs, and squamous cell carcinoma is known to cause cavitations. Culture of sputum and blood, including evaluation of first morning sputum for AFB, will be an essential part of the assessment but may not yield as much information as chest CT, and sputum culture should be done in conjunction with cytology and Gram stain. Bronchoscopy should
be postponed until CT results are available. Bronchoscopic biopsy is potentially detrimental if the lesion is an abscess since the airway could flood with pus if the entire cavity wall is penetrated.

Chest CT further confirms a parenchymal abscess in the right upper lobe with cavitation and air within the cavity. Bronchoscopy reveals pus in the airway and extrinsic compression of the bronchi. A lavage sample is obtained, but biopsies are not taken due to the clinical impression that this is a lung abscess.

Q 3. What organisms are most commonly isolated in lung abscesses?
A) Anaerobic bacteria.
B) Aerobic bacteria.
C) Tuberculosis.
D) Mixed aerobic/anaerobic bacteria.

Answer And Discussion
The correct answer is “A.”  Anaerobic bacteria.

Anaerobes are isolated most often, followed by mixed anaerobic/aerobic bacteria, followed by aerobic bacteria alone (especially staphylococci).

Gram stain of sputum demonstrates gram-positive cocci and gram-negative rods. Cultures are pending. Tuberculin skin test is negative.

Q 4. What is the most appropriate therapy for this patient?
A) Refer for surgical drainage.
B) Oral levofloxacin.
C) Intravenous clindamycin.
D) Intravenous metronidazole.
E) Intravenous ceftriaxone.

Answer And Discussion
The correct answer is “C.” Intravenous clindamycin.

Most lung abscesses are polymicrobial, but the most important aspect in treatment appears to be the use of an antibiotic active against anaerobes. Intravenous clindamycin is the usual choice for lung abscess due to its coverage of anaerobes and Streptococcus pneumoniae. Metronidazole is less effective, failing in up to 50% of cases of putrid lung abscess. A beta-lactam with beta-lactamase inhibitor (e.g., piperacillin/tazobactam) is another good choice. Ceftriaxone and levofloxacin offer poor coverage of anaerobes. Surgical drainage of lung abscesses is needed in only 5–10% of cases. Most resolve with just antibiotics.