The role of viral and bacterial infections in the pathogenesis of IPF: a systematic review and meta-analysis.

BACKGROUND Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease. Several risk factors such as smoking, air pollution, inhaled toxins, high body mass index and infectious agents are involved in the pathogenesis of IPF. In the present study, this meta-analysis study investigates the prevalence of viral and bacterial infections in the IPF patients and any possible association between these infections with pathogenesis of IPF. METHODS The authors carried out this systematic literature review from different reliable databases such as PubMed, ISI Web of Science, Scopus and Google Scholar to December 2020.Keywords used were the following "Idiopathic pulmonary fibrosis", "Infection", "Bacterial Infection" and "Viral Infection", alone or combined together with the Boolean operators "OR", "AND" and "NOT" in the Title/Abstract/Keywords field. Pooled proportion and its 95% CI were used to assess the prevalence of viral and bacterial infections in the IPF patients. RESULTS In this systematic review and meta-analyses, 32 studies were selected based on the exclusion/inclusion criteria. Geographical distribution of included studies was: eight studies in American people, 8; in European people, 15 in Asians, and one in Africans. The pooled prevalence for viral and bacterial infections w ere 53.72% (95% CI 38.1-69.1%) and 31.21% (95% CI 19.9-43.7%), respectively. The highest and lowest prevalence of viral infections was HSV (77.7% 95% CI 38.48-99.32%), EBV (72.02%, 95% CI 44.65-90.79%) and Influenza A (7.3%, 95% CI 2.66-42.45%), respectively. Whereas the highest and lowest prevalence in bacterial infections were related to Streptococcus sp. (99.49%, 95% CI 96.44-99.9%) and Raoultella (1.2%, 95% CI 0.2-3.08%), respectively. CONCLUSIONS The results of this review were confirmed that the presence of viral and bacterial infections are the risk factors in the pathogenesis of IPF. In further analyses, which have never been shown in the previous studies, we revealed the geographic variations in the association strengths and emphasized other methodological parameters (e.g., detection method). Also, our study supports the hypothesis that respiratory infection could play a key role in the pathogenesis of IP.