No abstract

Fifty clinical Mycoplasma pneumoniae strains were isolated from 370 children with respiratory tract infections. Four strains were susceptible to macrolides, while the other 46 (92%) were macrolide resistant. The molecular mechanism of resistance was shown to be associated with point mutations in 23S rRNA at positions 2063 and 2064.Mycoplasma pneumoniae is a common pathogen found in respiratory tract infections of children and teenagers and is commonly treated with macrolides. In recent years, strains which are resistant to common drugs have been isolated from patients (1,(3)(4)(5)(6)(7)(8). In order to evaluate the prevalence of macrolide resistance, we collected clinical samples during 2003 to 2006, cultured M. pneumoniae isolates, and screened for macrolide drug resistance. We investigated the mechanism of resistance by examining the erythromycin target site in the 23S rRNA gene of these strains.Throat swab specimens were collected from 300 inpatient and 70 outpatient children with respiratory tract infection at the Pediatric Department of Beijing Friendship Hospital, affiliated with Capital Medical University, during June 2003 to June 2006. Modified Hayflick medium was used for the isolation and growth of M. pneumoniae. Nested PCR was carried out to verify the identity of M. pneumoniae, using primers which amplify part of the 16S rRNA gene as described previously (2). The MICs of erythromycin, azithromycin, and josamycin required to inhibit M. pneumoniae growth were determined by the microdilution method (1). A reference strain, FH, was used as a drug-sensitive control. Erythromycin resistance was defined as having a MIC of Ն32 g/ml in accordance with the 2006 standards recommended by the CLSI (formerly NCCLS). To examine the molecular mechanisms of drug resistance, the 23S rRNA gene was amplified by nested PCR and the product was sequenced as described previously (8). The DNA sequences were compared with the sequence of M. pneumoniae M129 (GenBank accession no. X68422).Fifty clinical M. pneumoniae strains (44 of them from inpatients) were isolated from the 370 specimens collected. Four strains were susceptible to macrolides, and the other 46 (92%) strains were macrolide resistant. MICs of resistant strains to erythromycin, azithromycin, and josamycin were higher than that of the reference strain and higher than the CLSI guidelines (especially in the case of erythromycin and azithromycin). Table 1 shows the MIC range, MIC 50 , and MIC 90 of clinical isolate strains and the M. pneumoniae reference strain.The 23S rRNA gene sequences of four susceptible strains and the reference strain FH were identical to that of the M.

Sorting nexins (SNXs) are phosphoinositide-binding proteins implicated in the sorting of various membrane proteins in vitro, but the in vivo functions of them remain largely unknown. We reported previously that SNX10 is a unique member of the SNX family genes in that it has vacuolation activity in cells. We investigate the biological function of SNX10 by loss-of-function assay in this study and demonstrate that SNX10 is required for the formation of primary cilia in cultured cells. In zebrafish, SNX10 is involved in ciliogenesis in the Kupffer's vesicle and essential for left-right patterning of visceral organs. Mechanistically, SNX10 interacts with V-ATPase complex and targets it to the centrosome where ciliogenesis is initiated. Like SNX10, V-ATPase regulates ciliogenesis in vitro and in vivo and does so synergistically with SNX10. We further discover that SNX10 and V-ATPase regulate the ciliary trafficking of Rab8a, which is a critical regulator of ciliary membrane extension. These results identify an SNX10/V-ATPaseregulated vesicular trafficking pathway that is crucial for ciliogenesis, and reveal that SNX10/V-ATPase, through the regulation of cilia formation in various organs, play an essential role during early embryonic development.