Re: Pandemic influenza H1N1, legionellosis, splenic rupture, and vascular thrombosis: A dangerous cocktail
Sir,
A variety of pulmonary and extrapulmonary complications may occur in people with H1N1 influenza, including secondary bacterial pneumonia, encephalitis, rhabdomyolysis, and vascular thrombosis. However, the simultaneous development of different clinical pictures in a single patient is a rare event. We report an unusual case characterized by splenic rupture and extensive vascular thrombosis in a patient with pneumonia caused by a concurrent infection with Legionella and 2009 A (H1N1) virus. A previous healthy 42-year-old man was hospitalized because of fever (39?C) and progressive dyspnoea. On admission, blood test showed a severe anemia (Hb 5 g/dl), white blood cells were 15.8 K/μL. Creatine phosphokinase (CPK) was 1600 mg/dl, creatinine 1,7 mg/dl and sodium (Na+) values were 130 mEq/L. Chest X-ray revealed bilateral lung infiltrates and areas of consolidation. Antibiotic treatment with ceftriaxone plus levofloxacin, and antiviral treatment with oseltamivir were started. Non-invasive mechanical ventilation with continuous positive airway pressure (CPAP) was initiated since the PaO 2 /FiO 2 ratio was below 250. The patient was tested for 2009 A (H1N1) influenza virus by reverse-transcription polymerase chain reaction (PCR) test on a throat swab. On admission he was also tested for Legionella by urinary antigen test and PCR in blood samples. Legionella DNA detection through PCR in peripheral blood samples represents a useful, convenient and non-invasive method for the diagnosis of Legionella pneumonia, but the test sensitivity is higher if performed on bronchoalveolar lavage or sputum. We chose to perform PCR on blood sample because the cough was not productive. The results of assays were positive for both H1N1 and Legionella infection. A total body computed tomography (CT) scan confirmed the presence of an extensive bilateral interstitial pneumonia, but it also showed signs of incipient splenic rupture [Figure 1]a and b. The patient did not have any history of previous trauma. Doppler echocardiographic examination was negative. He underwent splenectomy and histological examination showed diffuse splenic intravascular coagulation. One week later, the patient presented with dyspnoea, abdominal pain and new onset of fever. A CT scan showed a subfrenic abscess and pulmonary artery thromboembolism. A right lower limb deep phlebothrombosis was also found. Clinical investigations excluded other diseases. Bone marrow biopsy for hematological diseases, autoimmunity screening and complete screening for thrombophilia were negative. The patient was treated with intravenous meropenem plus amikacin and enoxaparin with full clinical recovery.
Spontaneous splenic rupture is a rare but life-threatening complication of acute infections such as malaria and infectious mononucleosis. Anedoctical cases of spontaneous rupture of the spleen have been described during the course of legionellosis. [1],[2] Here, splenic rupture and extensive vascular thrombosis developed in a patient with pneumonia caused by a concurrent infection with Legionella and 2009 A (H1N1) virus. Pandemic influenza and pneumonia due to Legionella pneumophila Scientific Name Search are not rare co-infections. [3] It is important to investigate potential risk factors for Legionella such as previous hospitalization, chronic co-morbidity and travel. In our patient, the infection was community-acquired. Innate immune responses are critical in controlling both L. pneumophila and H1N1 virus. During the acute phase of the disease, both H1N1 influenza and legionellosis are associated with impairment of the innate immune response characterized by depletion of plasmacytoid dendritic cells (pDCs) with possible recruitment in the infected lungs. [4],[5] On the other hand, we cannot exclude that H1N1 and Legionella co-infection may drive dysregulation of host immunity leading to an exaggerated inflammatory response and endothelial activation which contribute to development of severe clinical manifestations. During the influenza pandemic wave, clinicians should remain alert about unusual clinical pictures resulting from concomitant infections.
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