Spread of multidrug resistance among Ureaplasma serovars, Tunisia

Ureaplasma spp. have been implicated in a variety of clinical conditions and certain serovars are likely to be disease-associated. Hence, the ascending trend of Ureaplasma spp. resistance to antimicrobials should deserve more attention. Here we assessed the extent of antimicrobial resistance of Ureaplasma serovars in Tunisia, and investigated the underlying molecular basis.

This study included 101 molecularly typed Ureaplasma spp. clinical strains isolated over a 12-year time period (2005-2017). The antimicrobial susceptibility was tested against nine antibacterial agents using the broth microdilution method. Neighbor-joining tree was constructed to establish the phylogenetic relationships among isolates.

We found that all ureaplasma isolates were resistant to ciprofloxacin and erythromycin, intermediately resistant to azithromycin, and susceptible to doxycycline, moxifloxacin and josamycin. Ofloxacin and levofloxacin resistance was found in 73.27 and 17.82%, respectively, while 37.62% of isolates proved resistant to tetracycline. Consequently, we detected an elevated multidrug resistance rate among ureaplasma isolates (37.62%), particularly among serovars 2, 5, 8, and 9 (77.77% overall), as well as serovars 4, 10, 12, and 13 (52.63% overall). In most cases, drug resistance was found to be associated with known molecular mechanisms, yet we have identified two novel mutations in the L22 protein, which might be associated with macrolide-resistance.

To our knowledge, this is the first study that reports the widespread expansion of multidrug resistance among Ureaplasma serovars, a finding of importance in terms of both surveillance and antimicrobial usage.