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.

ObjectiveTo analyse the independent and combined associations of postlunch napping duration and night-time sleep duration with risk of cognitive impairment among Chinese elderly.DesignA cross-sectional study.SettingWe analysed the data from Zhejiang Ageing and Health Cohort, a population-based survey of seven counties located in Zhejiang province in eastern China.Participants10 740 participants aged 60 years or older were included in final analysis.Primary and secondary outcome measuresCognitive impairment was assessed through Mini-Mental State Examination. Data on sleep-related characteristics was collected in the behavioural habits section within the questionnaire.ResultsRelative to participants with 1–30 min of postlunch napping, those who did not nap and who napped longer had significantly higher risks for cognitive impairment. OR of cognitive impairment were 1.41 (95% CI 1.14 to 1.75) for participants with longer night-time sleep duration (≥9 hours), compared with those sleeping 7–8.9 hours. In addition, combined effects were further identified. Participants with both longer night-time sleep duration (≥9 hours) and longer postlunch napping duration (>60 min) (OR=2.01, 95% CI 1.30 to 3.13), as well as those with both longer night-time sleep duration (≥9 hours) and appropriate postlunch napping duration (1–30 min) (OR=2.01, 95% CI 1.20 to 3.38), showed significantly higher risk of cognitive impairment than those with sleeping 7–8 hours and napping 1–30 min. Meanwhile, a 34% increase in odds of cognitive impairment was observed in participants with both shorter night-time sleep duration (5–6.9 hours) and no napping.ConclusionBoth postlunch napping duration and night-time sleep duration were independently and jointly associated with cognitive impairment, which needs verification in prospective studies.

Throat swabs from children with suspected Mycoplasma pneumoniae (M. pneumoniae) infection were cultured for the presence of M. pneumoniae and its species specificity using the 16S rRNA gene. Seventy-six M. pneumoniae strains isolated from 580 swabs showed that 70 were erythromycin resistant with minimum inhibitory concentrations (MIC) around 32–512 mg/L. Fifty M. pneumoniae strains (46 resistant, 4 sensitive) were tested for sensitivity to tetracycline, ciprofloxacin, and gentamicin. Tetracycline and ciprofloxacin had some effect, and gentamicin had an effect on the majority of M. pneumoniae strains. Domains II and V of the 23S rRNA gene and the ribosomal protein L4 and L22 genes, both of which are considered to be associated with macrolide resistance, were sequenced and the sequences were compared with the corresponding sequences in M129 registered with NCBI and the FH strain. The 70 resistant strains all showed a 2063 or 2064 site mutation in domain V of the 23S rRNA but no mutations in domain II. Site mutations of L4 or L22 can be observed in either resistant or sensitive strains, although it is not known whether this is associated with drug resistance.