An 82-year-old nursing home resident with a history of hypertension and chronic obstructive pulmonary disease (COPD) is brought to the emergency department after 2 days of fever, cough, and lethargy. He was treated with acetaminophen at the nursing home, but was found to be very confused this morning. His oral intake has also been poor. His daily medications include lisinopril, hydrochlorothiazide, and tiotropium. He has never been hospitalized for a COPD exacerbation or pneumonia. At the nursing home, there have been two cases of mild febrile illness over the past two weeks.
In the emergency department, he is ill-appearing and obtunded. His temperature is 39.4 C (103 F), blood pressure is 107/60 mm Hg, pulse is 68/min, and respirations are 26/min. Pulmonary examination reveals crackles at the left lung base. Bowel sounds are hyperactive and his abdomen is soft. There are no meningeal signs present.
Laboratory studies reveal:

A chest x ray reveals an ill-defined infiltrate at the left lung base.
Piperacillin-tazobactam and vancomycin are started empirically. Over the next 48 hours, his clinical status continues to deteriorate. A repeat chest x ray reveals progressive infiltrates with worsening left lower lobe consolidation.
This patient's condition is most likely to respond to which of the following?

Question

An 82-year-old nursing home resident with a history of hypertension and chronic obstructive pulmonary disease (COPD) is brought to the emergency department after 2 days of fever, cough, and lethargy.  He was treated with acetaminophen at the nursing home, but was found to be very confused this morning.  His oral intake has also been poor.  His daily medications include lisinopril, hydrochlorothiazide, and tiotropium.  He has never been hospitalized for a COPD exacerbation or pneumonia.  At the nursing home, there have been two cases of mild febrile illness over the past two weeks.
In the emergency department, he is ill-appearing and obtunded.  His temperature is 39.4 C (103 F), blood pressure is 107/60 mm Hg, pulse is 68/min, and respirations are 26/min.  Pulmonary examination reveals crackles at the left lung base.  Bowel sounds are hyperactive and his abdomen is soft.  There are no meningeal signs present.
Laboratory studies reveal:

A chest x ray reveals an ill-defined infiltrate at the left lung base.     
Piperacillin-tazobactam and vancomycin are started empirically.  Over the next 48 hours, his clinical status continues to deteriorate.  A repeat chest x ray reveals progressive infiltrates with worsening left lower lobe consolidation.
This patient's condition is most likely to respond to which of the following?

Quizplus · Accepted Answer

11ec193a_9631_b414_853d_875480b6758e_MD0002_00 This patient's underlying risk factors (elderly age, COPD, nursing home resident), clinical presentation (confusion, high fever with bradycardia), laboratory abnormalities (hyponatremia, thrombocytopenia, elevated LFTs), and failure to respond to vancomycin and piperacillin-tazobactam are strongly suggestive of Legionella pneumonia. Legionella species are facultative intracellular gram-negative bacilli whose natural habitats are aquatic bodies (e.g., lakes, streams, man-made reservoirs, standing water). There are no pathognomonic or highly specific clinical, laboratory, or radiological features for Legionella infection. The most common x-ray finding is a unilobar infiltrate that progresses to consolidation. Patients with suspected Legionella pneumonia should have both a urinary Legionella antigen test (detects only L. pneumophila, serogroup 1) and a respiratory sample (e.g., sputum, BAL) for Legionella culture. Suspected or proven Legionella pneumonia requires treatment with a respiratory fluoroquinolone (e.g., levofloxacin) or "newer" macrolide (e.g., azithromycin), as both have good lung penetration with potent intracellular activity. (Choice A) Ampicillin and piperacillin-tazobactam are both beta-lactam antibiotics and are ineffective against Legionella. Ampicillin is commonly used to treat Listeria, which causes meningitis/sepsis but not pneumonia. (Choice C) Linezolid is approved for treating MRSA pneumonia and is as effective as vancomycin. However, vancomycin and linezolid are not effective against Legionella. (Choice D) Metronidazole is effective for anaerobic aspiration pneumonia but not for Legionella. (Choice E) Oseltamivir treats primary influenza pneumonia, which more commonly shows bilateral reticular or reticulonodular opacities. Educational objective: Legionella pneumonia usually presents with fever, relative bradycardia, possible neurologic and GI symptoms, and potential unilobar chest x-ray infiltrate progressing to consolidation. Suspected patients with Legionella pneumonia should have both a urinary antigen test and a Legionella culture from a respiratory sample to confirm diagnosis. Treatment consists of respiratory fluoroquinolones (e.g., levofloxacin) or "newer" macrolides (e.g., azithromycin) while awaiting results. __________ References: An update on Legionella (http://www.ncbi.nlm.nih.gov/pubmed/20051846)

An 82-Year-Old Nursing Home Resident with a History of Hypertension