With this theoretical background in mind, early studies associating various bacteria with PBC re-attract interest: E. coli has been reported to be present in excess in the feces of patients with PBC. In addition, the incidence of urinary tract infections often induced by E. coli is high in PBC patients [73, 135] , and history of urinary tract infections increases the risk of PBC [117] . Another microorganism that has been proposed as a candidate for the induction of PBC is Novosphingobium aromaticivorans [136] . Titers of antibodies against lipoylated bacterial proteins of this ubiquitous organism, which metabolizes organic compounds including estrogens, were 1,000-fold higher compared to those against E. coli in patients with PBC, but no antibodies were observed in a large cohort of healthy subjects. Lactobacilli and Chlamydia, which show some structural homology with the autoantigen (although reactivity against them is considerably less than that against either E. coli or N. aromaticivorans), have also been implicated as putative pathogens, as have Helicobacter pylori and Mycobacterium gordonae [137] [138] [139] [140] . Recently, a case of PBC following lactobacillus vaccination for recurrent vaginitis was reported. The vaccine contained Lactobacillus salivarius, which exerts a high homology to the beta-galactosidase of Lactobacillus delbrueckii (LACDE BGAL [266] [267] [268] [269] [270] [271] [272] [273] [274] [275] [276] [277] [278] [279] [280] , and cross-reactivity of patients' autoantibodies against the human PDC-E2 212-226 epitope and LACDE BGAL [266] [267] [268] [269] [270] [271] [272] [273] [274] [275] [276] [277] [278] [279] [280] was found. Affinity to the Lactobacillus epitope was higher than to the native mammalian, suggesting that antimicrobial reactivity may have preceded that to the self-mimic [141] . However, the AMA status of this patient before repetitive lactobacillus vaccination could not be assessed and causal relation of lactobacillus exposure and development of PBC remains speculative also in this study.