2009 AH1N1 - associated pneumonia, clinical, microbiological and pathological analysis of 15 fatal cases

Abstract

The objective of the study was to describe clinicopathological, microbiological and radiological characteristics of 15 patients who died following 2009 AH1N1 - associated pneumonia. As materials and methods were reviewed clinical, radiological, microbological, and pathological datas (with emphasis on the pulmonary pathology findings) of 15 fatal cases of 2009 A I41N1 associated pneumonia hospitalised between November 2009 and January 2010 in Republican Clinical Hospital (RCH), Chisinau, Republic of Moldova. Most of the 15 decedents - 13 (86,6%) - were women (2 of whom were pregnant and 2 postpregnant). The mean age in the reviewed cases was 37,4 years. Comorbidities were presents in 10 cases, most frequent being hypertension (6 cases) and obesity (4 cases). The mean time from onset of symptoms to admission RCH was 6,5 days (range 3­ 13). The mean time from onset of symptoms to death, and from hospitalization to death was 16,91 (range 3-27 days) and 10,39 days (range 3 hours-23 days) days respectively. All patients had clinical criteria for SDRA and required mechanical ventilation during the first 24 hours of hospitalization. Chest radiographs demonstrated, in all cases, bilateral, confluent, patchy opacities with subtotal or total extent. In 3 cases was detected spontaneous pneumotorax. Bacteriological exam in 7 of 8 sputum specimen revealed Pseudomonas aeruginosa. Histopathologic changes consist of focal to extensive diffuse alveolar damage (DAD) in 12 patients often associated with marked hyaline membrane formation. Four of these 12 DAD cases showed only acute DAD. Three of 12 cases showed acute and organizing DAD. Five of 12 cases had fibrosing and organizing DAD. Autopsy evidence of mixed bronchopneumonia (viral + bacterial), predominantly with total extent, were observed in all decedents. In 11 cases was present predominantly a purulent exudate and in 4 cases - predominantly hemorrhagic. Acute desquamative tracheobronchitis was observed in all patients. In 10 of these cases was found a serohemorrhagic component, in 3 cases a fibrinopurulent component and necrotizing one in 2 cases. Desquamative bronchiolitis with metaplasia of bronchial epithelium were observed in 3 cases. Serofibrinous pleurisy was found in 6 decedents. In conclusion we say that pulmonary pathological changes in fatal cases, caused by 2009 A H1N1 influenza virus, were similar to those described in the past pandemics. Superimposed bacterial infection of the respiratory tract was common. Comorbidities and pregnancy can be risk factors for death.