Ankylosing spondylitis (AS) is a chronic inflammatory arthritis of unknown origin. Its autoimmune origin has been suggested but never proven. Several reports have implicated K. pneumoniae as a triggering or perpetuating factor in AS; and the HLA-B27 antigen has also been found in association with AS. But there is no satisfactory explanation of why the presence of HLA-B27 predisposes to AS and the precise role played by K. pneumoniae in the disease has not yet been clarified. However, various studies have shown that the results of molecular, immunological, and microbiological studies could establish the link between K. pneumoniae infections and HLA-B27 in the aetiopathogenesis of AS. In this review, we have examined the evidence linking the interaction between K. pneumoniae infections and HLA-B27 in AS, and tried to exploit the possible mechanisms by which K. pneumoniae infections might induce pathologic processes to develop novel diagnostic criteria. Finally, we have also summarized some dietary regimens that could be helpful in the therapeutic management of AS patients.