Meleumycin

Reversed-phase liquid chromatography coupled with photo-diode array (PDA) detection and electrospray ionization tandem mass spectrometry (ESI-MS/MS) was used to characterize the components of meleumycin, a 16-membered macrolide antibiotic produced by fermentation. In total 31 components were characterized in commercial samples, including 12 impurities that had never been reported before and 12 others that were partially characterized. The structures of these unknown compounds were deduced by comparison of their fragmentation patterns with those of known components. Their ultraviolet spectra and chromatographic behavior were used to confirm the proposed structures: e.g. λmax shift from 232 nm to 282 nm would indicate the presence of an α-, β-, γ-, δ-unsaturated ketone instead of a normal α-, β-, γ-, δ-unsaturated alcohol in the 16-membered ring of the examined components. Compared to other methods, this LC/MS(n) method is particularly advantageous to characterize minor components at trace levels in multi-components antibiotics, in terms of sensitivity and efficiency.

To investigate the infection and the drug resistance status of mycoplasma and chlamydiae in genitourinary tracts of children with suspected nongonococcal urethritis (NGU) and provide information for clinical rational administration of antimicrobial agents.

Samples of genitourinary tract secretion from 146 children who were suspected of having nongonococcal urethritis or colpitis were collected and tested for mycoplasma via culture and for chlamydia with antigen detection. Meanwhile, susceptibility test was carried out on the samples which were positive in mycoplasma cultivation. Chlamydia antigen was detected by the polymer conjugate-enhanced (PCE) indirect enzyme immunoassay (EIA) (IDEIA PCE Chlamydia; DAKO). The mycoplasma culture medium was produced by Nanjing Liming Biological Products Co,. Ltd. Antibiotics used for susceptibility test were erythromycin, roxithromycin, josamycin, leucomycin, meleumycin, rovamycin, azithromycin, clarithromycin, cycloate erythromycin, and clindamycin.

Fifteen samples were positive for Chlamydia trachomatis (Ct) by antigen detection (10.3%), 82 samples were positive in mycoplasma cultivation (56.2%), and among the 82 samples, 58 were positive for Ureaplasma urealyticum (Uu, 39.7%), 9 were positive for Mycoplasma hominis (Mh, 6.2%), and 15 were positive for Uu and Mh (10.3%). Of all the samples, 4 were positive for both Uu and Ct (2.7%). The rates of drug resistance of the 10 commonly used antibiotics were as follows: erythromycin 32.9%, roxithromycin 41.5%, josamycin 19.5%, leucomycin 22.0%, meleumycin 28.0%, rovamycin 30.5%, azithromycin 37.8%, clarithromycin 26.8%, davercin 24.4%, and clindamycin 26.8%, respectively. The results indicated that drug resistance rates of josamycin and leucomycin were the lowest, and the rates of roxithromycin and azithromycin were the highest.

The infection rates of mycoplasma and chlamydia in children suspected NGU were high. Mycoplasma showed drug resistance to a different degree to 10 common antibiotics. The results of chemosensitivity showed that josamycin had the highest susceptibility rate.