Association between Klebsiella pneumoniae and ankylosing spondylitis: A systematic review and meta‐analysis

Abstract Aim The aim of this study is to evaluate the association between Klebsiella pneumoniae infection and ankylosing spondylitis (AS). Method Five electronic databases, PubMed, Embase, Medline, Web of Science, and Scopes, were searched until September 29, 2021. Cohort and case‐control studies that assessed the association between K. pneumoniae infection and AS were included. Pooled odds ratio (OR) was selected to show the effect size. Subgroup analysis (active or inactive AS) and 2 forms of sensitivity analysis were conducted. All statistical analyses were conducted by using STATA 12.0. Results There were 25 case‐control studies finally included, including 8 studies concerning presence of K. pneumoniae in feces, and 17 studies concerning serum antibody (immunoglobulin [Ig]G, IgM, IgA) against K. pneumoniae . The results suggested that when compared with healthy people, presence of K. pneumoniae in feces was associated with AS (OR: 5.65; 95% CI: 1.68‐19.00). Similarly, when compared with healthy people, higher positive rates of IgA (OR: 6.28; 95% CI: 3.32‐11.91) and IgG (OR: 5.22; 95% CI: 1.36‐19.99) were observed. Subgroup analyses suggested that association between K. pneumoniae and AS appears stronger in active AS. Conclusion When compared with healthy people, a significantly higher positive rate of K. pneumoniae in feces, serum IgA and IgG were observed in patients with AS, suggesting that K. pneumoniae probably plays a crucial role in the occurrence of AS. The findings in this study need further prospective investigations for confirmation.