Escherichia coli and Proteus mirabilis are common single- and polymicrobial urinary tract infections which can survive under various oxygen levels, including inside of stone matrices. Therefore, we aimed to investigate and compare the calcium oxalate monohydrate (COM) lithogenic activities including COM crystal growth and aggregation under microaerobic conditions of E. coli and P. mirabilis isolated from the same stone matrix. The crystal growth was analyzed at the delta crystal area while the crystal aggregation was analyzed as the number of crystal aggregates. The results showed that compared to blank control, E. coli, P. mirabilis and the co-culture of E. coli and P. mirabilis were able to significantly promote COM crystal growth under microaerobic conditions. Interestingly, the delta crystal area in the co-culture under microaerobic conditions was larger than that of E. coli alone and P. mirabilis alone. In addition, only P. mirabilis alone and the co-culture were able to significantly increase COM aggregates. This study demonstrated that single- and co-culture of E. coli and P. mirabilis could promote COM crystal growth and aggregation under microaerobic conditions. The co-culture of E. coli and P. mirabilis may provide the combination effect on COM crystal interactions. The bacterial surfaces and the important effects on bacteria-crystal interactions should be further evaluated.
Keywords: Escherichia coli; Proteus mirabilis; calcium oxalate monohydrate; co-culture; crystal aggregation; crystal growth; kidney stones.