J Orsini, J Yunen, N Lalane, W Izarnotegui
community-acquired pneumonia, legionella pneumophila, legionella spp., legionnaires’ disease
J Orsini, J Yunen, N Lalane, W Izarnotegui. Legionnaires’ disease: do not forget the fluoroquinolones or macrolides.. The Internet Journal of Emergency and Intensive Care Medicine. 2009 Volume 12 Number 1.
Atypical community-acquired pneumonia pathogens, such as
An 85-year-old man was admitted to the hospital for generalized weakness, fever and confusion for 2 days. His past medical history was remarkable for hypertension, chronic obstructive pulmonary disease, atrial fibrillation, benign prostatic hypertrophy, degenerative joint disease and gastroesophageal reflux disease. His family denied any recent travel, exposure to bodies of water or contact with ill people.
Vital signs on admission were: blood pressure of 195/93 mmHg, heart rate of 109 beats/minute, respiratory rate of 34 breaths/minute and temperature of 103.8ºF. Oxygen saturation was 84% breathing room air that improved to 94% while receiving oxygen at 3 liters/minute by nasal canula. Physical examination showed a well-nourished white male, confused and tachypneic. Auscultation of the heart and lungs showed irregularly irregular rhythm and bilateral rales, respectively. Neurological examination showed no focal deficits. There was no cyanosis or clubbing.
Initial complete blood cell count results showed a white blood cell count of 24,600/mm3 [4,000 – 11, 000], a hemoglobin level of 14.8 g/dl [11 – 16] and a platelet count of 215,000/mm3 [160 – 400]. Relevant serum chemistry results included a sodium level of 143 mEq/L [135 – 145], a bicarbonate level of 19 mEq/L [24 – 30] and a creatinine level of 1.1 mg/dl [0.6 – 1.3]. Aspartate aminotransferase level was 303 units/L [10 – 37], an alanine aminotransferase level was 165 units/L [5 – 37], an alkaline phosphatase level was 426 units/L [56 - 155], a total bilirrubin level was 1.5 mg/dl [0.2 – 1.1] and a lactate dehydrogenase level was 581 units/L [60 – 200]. Phosphate level was decreased to 1.9 mg/dl [2.5 – 4.2] and a creatine kinase level was 601 units/L [38 – 174]. Arterial blood gas result showed a pH of 7.49 [7.35 – 7.45], a pCO2 of 26 mmHg [35 – 45] and a pO2 of 120 mmHg [85 – 100], with the patient breathing oxygen at 3 liters/minute by nasal canula. Chest radiography demonstrated a right middle lung density (Figure 1), and intravenous ceftriaxone (1 g Q24h) was initiated for possible pneumonia.
Computed tomography (CT) of the head did not show any abnormalities. Lumbar puncture was performed and cerebrospinal fluid analysis was within normal limits. Blood, urine and cerebrospinal fluid cultures were negative. His medical condition deteriorated with the development of severe hypoxemic respiratory failure and persistent fevers, for which the patient was placed on mechanical ventilation and transferred to the medical intensive care unit. Intravenous ceftriaxone was substituted for vancomycin (1 g Q24h) and piperacillin/tazobactam (2.25 g Q8h) due to worsening infiltrates on the chest radiographies. CT of the chest showed a dense consolidation with air bronchograms in the right upper lobe, lateral segment of the right middle lobe and right lower lobe (Figure 2).
On hospital day 3, intravenous azithromycin (500 mg Q24h) was added to the antimicrobial regimen because of a positive urine antigen and respiratory culture results for
Legionnaires’ disease is transmitted from the environment to humans by inhalation of an infectious aerosol and, in few cases, by microaspiration of contaminated water into the lungs (8, 9). Cooling towers, air conditioning units, ventilators, nebulizers and whirlpool baths have been described as sources of water contaminated with
The clinical diagnosis of Legionnaires’ disease is difficult. Among hospitalized patients with community-acquired pneumonia,
The chest radiography pattern in Legionnaires’ disease is nonspecific.
No currently available test is able to diagnose all
Empiric initial therapy for hospitalized patients with community-acquired pneumonia should always include coverage for
In conclusion, rapid clinical diagnosis of Legionnaires’ disease is important in selecting effective antimicrobial therapy in patients with pneumonia, since an unrecognized