IntroductionUreaplasma urealyticum is considered a part of the normal genital flora in human beings. It is found in about 70% of sexually active humans. It has also been associated with a number of diseases, such as nonspecific urethritis (1), infertility (2), or chorioamnionitis (3). The symptoms of U. urealyticum infection are variable in different people and bacterial strains (4). In addition, U. urealyticum has some effects on other pathogen infections in the genital tract and results in more complex mixed infections (5). Hostpathogen interactions and adapted immune responses are involved in the U. urealyticum infection processes, and these features make for variable virulence and antibiotic resistances in different populations (6).Quinolone antibiotics are used widely to deal with Ureaplasma infections. However, resistance to quinolone is an increasingly serious problem in today's clinical treatment of this pathogen (7). The most important reason for this situation is the improper uses of antibiotics. Furthermore, according to the guidelines of the Clinical and Laboratory Standards Institute (CLSI), the resistance or susceptibility of U. urealyticum is judged by the 'color change unit' . Unfortunately, the current clinical susceptibility testing programs, based on many commercial kits such as Mycoplasma IST2 kits (bioMerieux, Marcy l'Etoile, France), cannot accurately reflect the real resistance level of Ureaplasma.In 2009, an available CLSI-compliance susceptibility testing method was reported on by Beeton et al. (8). This method made it possible to test the quantity of Ureaplasma and the actual susceptibility of the organism. In this study, we detected the biofilm formation of different Ureaplasma strains, and then observed the Ureaplasma's susceptibility prebiofilm formation and postbiofilm formation. Some functional gene expressions were evaluated to analyze whether there was a correlation between these gene expressions and biofilm formation in the pathogen.Background/aim: To detect the effects on quinolone resistance due to biofilm formation activity in Ureaplasma urealyticum.Materials and methods: An improved checkerboard dilution susceptibility test was used to analyze the quinolone resistance of clinical Ureaplasma isolates and a postbiofilm formation susceptibility assay was used to compare the effects on the quinolone susceptibility between pre-and postbiofilm formations. Several important functional gene expressions were detected to evaluate their roles in the process of the quinolone resistance mechanism.
Results:The quinolone-resistant isolates produced more biofilms than the sensitive isolates. In both the quinolone-resistant and -sensitive groups, the minimal inhibitory concentrations after biofilm formation were higher than those before biofilm formation. The expression of the metabolism-related gene ureC in postbiofilm formation was higher than those in prebiofilm formation.
Conclusion:It seems that biofilm formation is quite important in the generation of quinolone resistance in Ureaplasma....