Occurrence of influenza A(H1N1)v infection and concomitant invasive pulmonary aspergillosis in a patient with chronic obstructive pulmonary disease

Invasive pulmonary aspergillosis (IPA) represents a leading cause of infection-related morbidity and mortality in highly immunocompromised patients for immunosuppressive agents or severe chemotherapy-induced granulocytopoenia, such as those with haematological malignancies or bone marrow transplantation. There is also a growing literature regarding IPA in patients without apparent risk factors including immunocompetent critically ill patients in intensive care units and those with chronic obstructive pulmonary disease (COPD) (Segal BH. N Engl J Med 2009; 360: 1870–84; Meersseman W. Clin Infect Dis 2007; 45: 205–16). In these patients, structural changes in the lungs, associated co-morbidities and steroid therapy have been recognised as major risk factors for IPA. Many authors have reported cases of IPA occurring during infection with influenza viruses, thus suggesting that acute respiratory viral infections could represent an adjunctive risk factor for IPA. We report the case of IPA and concomitant documented influenza A(H1N1)v infection in a patient affected by COPD. A 63-year-old woman admitted with fever and cough has been hospitalised for worsening dyspnoea. Past medical history revealed COPD secondary to cigarettes smoking (30–40 daily) since 20 years treated with inhalatory association of steroids and beta adrenergic agonists (salmeterol plus fluticasone) since 2 years and mild hypertension managed with angiotensin converting enzymes inhibitors (ramipril) both prescribed by her primary care physician. Neither signs and symptoms of COPD exacerbations, nor bacterial respiratory tract infections were reported in the previous 6 months. In addition, the patient did not live in proximity to construction and renovation areas. At the time of admission, physical examination showed bilateral crackles and wheezes at chest auscultation, fever (external corporeal temperature of 39 °C), heart rate of 100 bpm and normal blood pressure (125/75 mmHg). The arterial blood gas values in room air revealed a pH of 7.48, PaO2 of 61 mmHg and PaCO2 of 36.8 mmHg. Given the fact that this patient was admitted during the pandemic spread of influenza A(H1N1)v, the real-time PCR for H1N1 was performed with positive results. Routine blood test showed a haemoglobin of 14.2 g dl−1, white blood cell count of 19.2 × 109 l−1 (neutrophils 94.9% and lymphocytes 3.7%) and increased unspecific inflammatory indexes (C reactive protein of 14.9 mg dl−1); electrolytes and renal function tests were within the normal limits. Chest X-ray demonstrated diffuse bilateral interstitial infiltrates with no signs of pleural effusion and a normal cardiac silhouette (Fig. 1). Chest radiographs performed on day 1 (left) showing bilateral reticular-nodular infiltrates and on day 10 (right) showing extensive bilateral consolidations. These findings suggested the hypothesis of viral pneumonia with possible bacterial super-infection in a subject with worsening COPD. Thus, in an effort to clarify the aetiology of the pneumonia, blood and sputum cultures were collected and serology for Legionella, Mycoplasma and HIV was performed. In the acute phase, the patient was treated with i.v. steroids (methyl-prednisolone 40 mg b.i.d), empirical antimicrobial therapy (piperacillin-tazobactam 4.5 g t.i.d and levofloxacin 500 mg q.i.d.) and oseltamivir 75 mg b.i.d. In the following 48–72 h, the results of the microbiological tests surprisingly revealed florid cultures of Aspergillus fumigatus from the sputum. Serology for Legionella, Mycoplasma and HIV antibodies were negative. A stain of the sputum for acid-fast bacilli was also negative. Accordingly, liposomal Amphotericin B (4 mg kg−1 q.i.d.) was implemented. In spite of the aggressive therapy after 10 days, the clinical conditions of the patient progressively deteriorated with worsening of bilateral infiltrates on a subsequent chest roentgenogram (Fig. 1) and consequent respiratory failure (pH of 7.53, PaO2 of 49 mmHg, PaCO2 of 46 mmHg with a FiO2 of 40%) requiring mechanical ventilation. Furthermore, blood tests confirmed a persistent lymphopoenia (total lymphocytes count of 0.4 × 109 l−1). In the intensive care unit (ICU), a bronchoalveolar lavage was performed and cultures yielded again A. fumigatus. Despite the available treatment strategies, the patient did not improve and after 3 days, she died unfortunately. Histological sections of the lungs at autopsy showed extensive areas of pneumonia with multiple foci of abscess formation. Extensive infiltration by fungal hyphae was found invading blood vessel walls and permeating alveolar septa. Arterial lumens were completely occluded by plugs of fungi. In addition, many segmental bronchi showed denudation of the mucosa and replacement by proliferating epithelial cells showing squamous metaplasia (Fig. 2). Lung parenchyma showing invasive aspergillosis with typical morphological features of Aspergillus fumigatus, arranged in parallel, long, thin and dichotomously branching fungal hyphae (left, haematoxylin–eosin, o.m. ×400). Regenerative changes in bronchus showing bronchial squamous metaplasia (right, haematoxylin–eosin, o.m. ×200). To the best of our knowledge, this is the third case of documented novel influenza A (H1N1)v infection in an adult patient complicated by IPA (Lat A. Emerg Infect Dis 2010; 16: 971–3). Aspergillus spp. remains a major cause of morbidity and mortality in immunosuppressed patients with significant chemotherapy-induced neutropoenia due to haematological malignancies, solid organ neoplasia or bone marrow transplantation. However, isolation of Aspergillus spp. from the respiratory tract also occurs in immunocompetent individuals with underlying lung diseases mostly represented by COPD treated with chronic inhalatory steroids. This fact represents a simple colonisation in the majority of cases but, in patients with severe worsening COPD, may reflect an underlying IPA (Garnacho-Montero J. Critical Care 2005; 9: R191-9; Rello J. Clin Infect Dis 1998; 25: 1473–5). Critically ill patients admitted in intensive care units exhibit a complex decrease in immune function, represented by deactivation of macrophages and altered cellular response (Lederer JA. Shock 1999; 11: 153–9). Furthermore, it has been demonstrated that corticosteroids suppress neutrophil activity against Aspergillus hyphae (Roilides E. Infect Immun 1993; 61: 4870–7). These mechanisms may explain invasive Aspergillus infections occurring in some ICU patients without any apparent predisposing factors, and may also account for the association between steroid use and this invasive fungal infection. On the other hand, the occurrence of IPA complicating Influenza virus infections has been previously reported in the literature as single case reports or small series. The most frequent Influenza virus identified in these patients was the type A that is more common and exhibits more virulence than that of influenza virus B (Hasejima N. Respirology 2005; 10: 116–9; Alba D. An Med Interna 1996; 13: 34–36; Jariwalla AG. Thorax 1980; 35: 215–6; Lat A. Emerg Infect Dis 2010; 16: 971–3; Fischer JJ. JAMA 1979; 241: 1493–4). Although the exact patho-physiological mechanisms are still unclear, it appears that influenza A/B virus attacks the columnar ciliated respiratory epithelium of the airways with resultant necrosis, down to the level of the terminal bronchioles and alveoli. These damages resulted, after few days, in regenerative changes of bronchial mucosa represented by a non-ciliated squamous metaplastic hepitelium, a typical feature of influenza pneumonia. In these settings, without ciliary lung defences, secondary bacterial or fungal infections are reported (Clancy CJ. Chest 1998; 114: 629–34). Furthermore, influenza virus has been known to cause lymphopoenia and depression of T cell-mediated immunity, with unclear mechanisms (Lewis M. Chest 1985; 87: 691–3; Lee FE. Chest 2005; 128: 1863–7). As clinical and radiological presentation is often non-specific, careful evaluation of the above mentioned mechanisms and risk factors predisposing to the IPA is critical in achieving an early diagnosis, as the survival of patients with IPA depends largely on prompt institution of therapeutic measures (Rello J. Clin Infect Dis 1998; 25: 1473–5). As a matter of fact, it is difficult to determine whether this was either a case of IPA in a patient treated with inhaled and systemic steroids for COPD with superimposed influenza A(H1N1)v infection or a case of COPD exacerbation secondary to viral infection in a patient with IPA secondary to the chronic use of steroids. In our patient, with no history of immune diseases, the influenza A(H1N1)v infection may have precipitated a transient immunocompromised state, as suggested by the notable and persistent lymphopoenia. In addition, the same infection may have predisposed the respiratory epithelium to the secondary invasive fungal infection, as documented by the histological features of the lung sections, highly suggestive of an influenzal necrotising bronchitis associated with extensive areas of Aspergillus spp. pneumonia. On the other hand, the inhalatory chronic steroid therapy and the steroid boluses infused in the acute phase for worsening COPD of our patient may have caused an immune dysregulation leading to a subclinical fungal disease, that may have been eventually virulented by influenza A (H1N1)v infection with a fatal outcome. In conclusion, patients affected by COPD, in chronic steroid therapy and acute respiratory influenza infection, are at risk of developing IPA. Aspergillus spp. isolation from respiratory tract during an episode of respiratory function deterioration unresponsive to steroid and broad spectrum antimicrobial therapy should alert physicians caring these patients, for an invasive fungal infection. Radiological imaging does not provide specific lesions; on the other hand surrogate markers such as galactomannan in respiratory secretions may represent useful tools for early diagnosis and treatment. In loving memory of Professor Camillo Brandimarte, an outstanding physician, a precious friend and a sweet father.