Vesna Tripković

Unusually low prevalence of Mycoplasma genitalium in urine samples from infertile men and healthy controls: a prevalence study

Objective To detect Mycoplasma genitalium in urine samples of infertile men and men without any signs of infection in order to investigate whether M. genitalium and other genital mycoplasmas (Mycoplasma hominis and Ureaplasma spp) are found more often in urine samples of infertile men than in asymptomatic controls and to determine resistance to macrolides. Methods The study included first void urine samples taken from 145 infertile men and 49 men with no symptoms of urethritis. M. genitalium, Chlamydia trachomatis and Neisseria gonorrhoeae were detected by commercial PCR. Trichomonas vaginalis was detected by microscopy and culture. M. hominis and Ureaplasma spp were detected by culture. M. genitalium was detected by in-house conventional and real-time PCR. Results Two M. genitalium positive samples were found among samples obtained from infertile men. All asymptomatic men were M. genitalium negative. Macrolide resistance was not found in either of the two positive samples. Conclusions In comparison with reported data, an unusually low prevalence of M. genitalium was found in infertile men. The reasons for this unexpected result are not known; possibly, local demographic and social characteristics of the population influenced the result. Further studies to investigate M. genitalium in infertile and other groups of patients are needed.

Helicobacter pylori: In vitro Induction of Resistance to Azithromycin

Helicobacter pylori resistance to macrolides is possibly an important factor for the failure of macrolide therapy for H. pylori infection. The aim of this study was to assess the propensity of H. pylori to develop in vitro resistance to azithromycin. In 73 clinical isolates taken from patients before starting antimicrobial therapy of H. pylori infection, MIC was determined using an agar dilution method (Müller-Hinton agar with 7.5% unlysed horse blood, pH = 7.2, at 35°C, during 72 h in a humid microaerobic atmosphere). Each strain was first cultivated at half minimal inhibitory concentration (MIC) then in doubling concentrations until growth arrest. All experiments for induction of resistance were performed on the same media, incubation temperature, atmosphere and time of MIC determination. MIC interpretative standards for sensitivity, intermediate sensitivity and resistance of H. pylori to azithromycin were ≤2, 4 and ≥8 mg/l, respectively. Of 73 strains, 5 died during the experiments, and in the remaining 68 strains, serial passage with increasing azithromycin concentrations resulted in the development of resistance in 19 (26.9%) strains. Two strains had an MIC of 16 mg/l azithromycin. Thirty-three (48.5%) strains kept the same MIC or doubled their MIC, 16 (23.5%) strains had 4- to 16-fold MIC but still remained sensitive, 2 resistant strains had 128-fold MICs and 17 resistant strains had increased their MICs more than 128 times. Seventeen highly resistant strains (MIC >128 mg/l) were kept frozen at –70°C for 3 months in a brain-heart infusion broth with 15% glycerol. MIC was assessed again to determine the stability of resistance. Eleven strains kept MICs >128 mg/l, 2 became sensitive and 1 intermediate, but reverted easily, after only 2 passages, to an MIC of >128 mg/l azithromycin. Although macrolides are very active against H. pylori, the propensity to develop resistance in a high proportion of strains has a clear impact on the choice of the right combinations of macrolides with other agents as well as the dosage of the macrolide antibiotics.