Interstitial lung disease (ILD) comprises an array of heterogeneous parenchymal lung diseases that are associated with a spectrum of pathologic, radiologic, and clinical manifestations. There are ILDs with known causes and those that are idiopathic, making treatment strategies challenging. Prognosis can vary according to the type of ILD, but many exhibit gradual progression with an unpredictable clinical course in individual patients, as seen in idiopathic pulmonary fibrosis and the phenomenon of "acute exacerbation"(AE). Given the often poor prognosis of these patients, the search for a reversible cause of respiratory worsening remains paramount. Infections have been theorized to play a role in ILDs, both in the pathogenesis of ILD and as potential triggers of AE. Research efforts thus far have shown the highest association with viral pathogens; however, fungal and bacterial organisms have also been implicated. This review aims to summarize the current knowledge on the role of infections in the setting of ILD.

BackgroundDiffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is characterised by multifocal proliferation of neuroendocrine cells and belongs in the spectrum of pulmonary neuroendocrine tumors. Some patients with DIPNECH develop airflow obstruction but the relationship between the two entities remains unclear.MethodsWe performed a computer-assisted search of the Mayo Clinic's electronic medical records for biopsy-proven cases of DIPNECH. We extracted clinical, pulmonary function, imaging and histopathologic data along with treatments and outcomes.ResultsAmong 44 patients with DIPNECH 91% were female and median age was 65 years (IQR: 56–69 years); 73% were never smokers. 38 patients (86%) had respiratory symptoms including cough (68%) and dyspnea (30%); 45% were previously diagnosed to have asthma or COPD. Pulmonary function testing showed an obstructive pattern in 52%, restrictive pattern 11%, mixed pattern 9%, nonspecific pattern 23%, and normal 5%. On chest CT scan, 95% manifested diffuse nodules and 77% manifested mosaic attenuation. For management, 25% of patients were observed without pharmacologic therapy, 55% received an inhaled bronchodilator, 41% received an inhaled corticosteroid, 32% received octreotide; systemic steroids, azithromycin, or combination chemotherapy was employed in 4 patients (9%). Of 24 patients with follow-up PFT available, 50% remained stable, 33% worsened and 17% improved over a median interval of 21.3 months (IQR: 9.7–46.9 months).ConclusionDIPNECH occurs mostly in women and manifests diffuse pulmonary nodules and mosaic attenuation on imaging. It is commonly associated with airflow obstruction due to constrictive bronchiolitis, which manifests limited response to current pharmacologic therapy.

In recent years, advances in PCR techniques have aided in the rapid and accurate detection of common respiratory pathogens from patient specimens. Multiplex PCR can identify and differentiate a large panel of viral and bacterial targets simultaneously. Published studies have shown that multiplex PCR panels are more rapid and more sensitive methods of virus detection than cultures or antigen detection (1, 2). One such method, the FilmArray respiratory panel (FARP) (BioFire Diagnostics, Inc.), is a multiplex, nested PCR technique that can detect 17 common respiratory viruses and 3 bacterial targets in a single reaction in just over 1 h (3). Published studies have shown that for both immunocompetent and immunocompromised patients, the FARP identifies significantly more viral pathogens in both bronchoalveolar lavage (BAL) fluid and nasopharyngeal (NP) samples than viral cultures and direct fluorescent antibody staining and that the FARP is among the most sensitive of the available multiplex assays (1, 4-10). In addition, the FARP has a low hands-on time and very fast turnaround time. Since the FARP is associated with a significant cost to the laboratory and the patient, its judicious use is necessary.Choosing the least invasive, highest yield, and most cost-effective investigations in a stepwise manner has always been central to the practice of medicine. Patients who present with symptoms of a respiratory tract infection often undergo testing for respiratory viruses. The initial testing at our center may involve collection of an NP sample for influenza A and B and respiratory syncytial viruses. The comprehensive FARP is obtained for patients with complex conditions or those who are immunocompromised and have symptoms of upper or lower respiratory tract infections. In the presence of concurrent pulmonary infiltrates, fever, and hypoxia, patients (especially if immunocompromised) may then undergo a bronchoscopy with BAL with repeat FARP testing on the BAL sample. To date, no studies have compared the yield of FARP on BAL samples with the yield on NP samples. Whether additional microbiologic information is obtained from FARP testing on a BAL sample after testing on a NP swab is not known. This retrospective case-control study evaluates the concordance between FARP testing on NP and BAL samples.(Part of this research was presented as a poster at the American Thoracic Society International Conference, Denver, CO, 15 to 20 May 2015.) MATERIALS AND METHODSWe retrospectively reviewed the electronic medical records of all patients evaluated at the Mayo Clinic in Arizona between 1 June 2013, and 31 May 2014, who had FARP testing on both NP and BAL samples. All patients who were included had a BAL sample FARP (BAL FARP) performed within 7 days after an NP swab FARP (NP FARP) during the same hospitalization or illness episode. FARP results obtained on tracheal aspirates were excluded.Patient electronic medical records were reviewed, and the following information was obtained: demographics (age and sex) and the presence of immun...

Background The FilmArray Respiratory Panel (FARP) (BioFire Diagnostics, Inc.) is a multiplex, polymerase chain reaction (PCR) technique that can detect 17 respiratory viruses and 3 bacterial targets in a single reaction. Immunocompromised hosts (ICH) with respiratory illnesses often undergo bronchoscopy with bronchoalveolar lavage (BAL). This prospective study aimed to evaluate the yield and concordance of NP and BAL FARP testing when performed on the same patient concurrently. Methods From February to December 2016, 125 patients (100 ICH and 25 non-ICH) were enrolled. NP swabs and BAL samples were sent for FARP testing. Results The yield of the BAL FARP among ICH and non-ICH was 24% (24/100) and 8% (2/25), respectively. The yield of positive NP swabs in ICH was 27% (27/100) versus 4% (1/25) in non-ICH. The majority of patients (89%; 111/125) had concordant results between NP and BAL specimens. Of the 24 ICH patients who had a positive BAL FARP, the majority (79%) had the same pathogen detected from the NP swab. Conclusion The FARP may be useful in the ICH. Given the high concordance, in patients whom a pathogen is identified on the NP FARP, a FARP performed on BAL will likely yield the same result. However, if the NP FARP is negative, performing the test on a BAL sample may have an incremental yield.