Objective To study the resistance mechanism of Ureaplasma urealyticum (Uu) to erythromycin.Methods The susceptibility of 73 clinical isolates of Uu to erythromycin was evaluated by using broth dilution techniques. PCR and DNA sequencing were carried out to screen hot spot mutations at the variable region of 23S ribosomal RNA in erythromycin-resistant strains of Uu. Moreover, erythromycin resistance methylase genes (ermA, ermB, ermC) and efflux pump genes (mefA/E, msrA/B, mreA) were screened by using PCR with specific primers. Results There were 35 (47.95%) resistant Uu strains out of the 73 isolates, and the minimal inhibitory concentration varied from 8 to 32 mg/L among these resistant strains. The ermB gene was detected in 19 (54.29%) resistant strains, and msrA/B gene in 9 (25.71%) resistant strains. Two resistant strains harbored both ermB gene and msrA/B gene. No mutation at 23S ribosomal RNA or amplification of resistance-associated genes was noted in sensitive or reference strains of Uu. Conclusion The ermB and msrA/B genes may be responsible for the erythromycin resistance of Uu.

Objective To detect the msr gene which confers resistance to erythromycin, and ana-lyze its distributing difference between the two biovars of Ureaplasma urealyticum. Methods Broth dilution method was used to determine the minimum inhibitory concentrations (MIC) to erythromycin among 72 U. urealyticum clinical isolates. The msrA, msrB, msrC and msrD genes detection and biotyping of U. urea-lyticum were conducted using PCR. Results The MICs of 72 U. urealyticum isolates to erythromycin ranged from ≤0. 125 μg/ml to ≥128 μg/ml. MIC_(50) was 32 μg/ml and MIC_(50) was ≥128 μg/ml. Biotyping showed that biovar Parvo had 51 strains (51/72, 70.83%) and biovar T960 had 21 (21/72, 29.17%) strains.The msrA, msrB, msrC and msrD genes were obtained in 1, 12, 0 and 24 strains, respectively, with five strains carrying the msrB and msrD genes, and one strain carrying the msrA, msrB and msrD genes. There was no resistance difference to erythromycin between the two biovars when the MIC≥8 μg/ml was considered resistance to eryt hromycin. But the msrB gene was predominantly detected in biovar T960. Conclusion U. urealyticum clinical isolates harbeur the msrA, msrB and msrD genes, and the predominantly detected msrB gene is of biovar T960.

Objective To study the relationship between erythromyein sensitivity and ermB gene in 143 Ureaplasma urealyticum (Uu) clinical isolates. Methods We detected the minimum inhabit concen-trations (MICs) of Uu to erythromycin by broth dilution method and MIC≥8 μg/ml was used as standard concentration of resistance to erythromycin. Polymerase chain reaction was used to detect the ermB gene and biotype Uu with primers based on multi-band antigen gene. Results The MICs, MIC50 MIC90 of Uu to erythromycin were ≤0. 125 μg/ml to ≥128 μg/ml, 16 μg/ml, and ≥128 μg/ml, respectively, with a high resistance rate of 64.38%. ermB gene, which was mainly detected in Uu with MIC≥8 μg/ml, was positively detected in 40 out of 143 Uu strains (27.97%). No significant differences of the resistance to erythromycin and positive rate of ermB gene were found between the two biovars in the study . Conclusion ermB gene may probably be one of the important genes conferring resistance to erythromycin in Uu. Further studies are needed to discover the difference of resistance and mechanism of erythromycin between the two bi-ovars.

Objective To evaluate the efficacy and safety of omalizumab on the treatment of chronic spontaneous urticaria (CSU) by systemic review and meta-analysis.Methods Electronic databases,such as PubMed,Clinicaltrials.gov,the Cochrane Database of Systematic Reviews,and the Cochrane Central Register of Controlled Trials,were searched to collect randomized controlled trials (RCTs) about the efficacy and safety of omalizumab in the treatment of CSU.Two reviewers independently screened RCTs according to the inclusion and exclusion criteria,extracted data,and assessed the quality of the included RCTs.And then,a meta-analysis was carried out by using RevMan 5.3 software for comparisons of the efficacy and safety of the 75-,150-,300-,600-mg omalizumab groups versus the placebo group after 1-month treatment,as well as the total omalizumab group versus the placebo group.Results A total of 7 RCTs involving 1 365 patients were included in this meta-analysis.The results showed that the total omalizumab group and different omalizumab subgroups were superior in improving the urticaria activity score of 7 days (UAS7) and wheal number score of 7 days to the placebo group (all P ＜ 0.05).For the improvement in the itch severity score (ISS) of 7 days and complete response rate for main symptoms (UAS7 =0),the total omalizumab group,75-,150-and 300-mg omalizumab groups were superior to the placebo group (all P ＜ 0.05),but there were no significant differences between the 600-mg omalizumab group and the placebo group (P =0.07).The dermatology life quality index (DLQI) was better in the total omalizumab group,150-and 300-mg omalizumab groups than in the placebo group (all P ＜ 0.05),but no significant difference was observed between the 75-mg omalizumab group and the placebo group (P =0.50).There were no significant differences in the incidence of common adverse events or serious adverse events between the total omalizumab group as well as the 75-,150-and 300-mg omalizumab subgroups and the placebo subgroup (all P ＞ 0.05).Conclusions Omalizumab can improve clinical symptoms and life quality of patients with CSU,and is effective in improving the UAS,ISS,wheal number score,DLQI and complete response rate for main symptoms (UAS =0) with high safety.Subcutaneous injection of omalizumab at a dose of 150 or 300 mg/month shows the best efficacy in improving the clinical symptoms and life quality of patients with CSU.

Objective: To analyze changes in sensitivity of clinical strains of Ureaplasma urealyticum (Uu) to 9 kinds of common antibiotics from 2017 to 2018. Methods: The results of drug sensitivity testing of clinical Uu strains, which were isolated from 19 431 patients in Laboratory of Sexually Transmitted Disease (STD) , Department of Dermatology and Venereology, The Third Affiliated Hospital, Sun Yat-Sen University from 2007 to 2018, were analyzed retrospectively. Of the 19 431 patients, 6 076 were males, and 13 355 were females. Their age ranged from 15 to 68 years. The tested antibiotics included minocycline, doxycycline, erythromycin, azithromycin, clarithromycin, roxithromycin, ciprofloxacin, sparfloxacin and levofloxacin. Results: Resistance rates of clinical Uu strains to minocycline and doxycycline gradually decreased from 10.08% and 10.42% in 2007 to 1.15% and 2.61% in 2018, respectively, while sensitivity rates to minocycline and doxycycline gradually increased from 85.88% and 87.56% in 2007 to 97.02% and 96.42% in 2018, respectively. The resistance rate and sensitivity rate of clinical Uu strains to erythromycin fluctuated greatly during 2014—2017, with the resistance rate fluctuating around 20%, and the sensitivity rate fluctuating around 50%. The resistance rate of clinical Uu strains to azithromycin dropped rapidly from 42.02% in 2007 to 8.39% in 2011, and then fluctuated slightly around 10%. However, the sensitivity rate to azithromycin increased from 8.40% in 2007 to 86.05% in2011, and remained above 80% from then on to 2018. During 2007—2018, Uu strains showed low resistance rates (10%-20%) and high sensitivity rates to clarithromycin (80%-90%) , and the resistance and sensitivity rates to roxithromycin were similar to those to erythromycin. Uu strains showed constantly high resistance to ciprofloxacin (more than 80% after 2013) and low sensitivity (persistently less than 10%) . The sensitivity rate of clinical Uu strains to sparfloxacin fluctuated around 40%, while the resistance rate was maintained below 10% after 2011. The resistance and sensitivity rates of Uu strains to levofloxacin were similar to sparfloxacin, but the sensitivity rate to levofloxacin was relatively lower, which had been maintained at about 30%. Conclusion From 2007 to 2018, clinical Uu strains maintained a relatively stable low resistance rate and a high sensitivity rate to minocycline, doxycycline and clarithromycin, a high resistance rate and low sensitivity rate to ciprofloxacin, and a low resistance rate and sensitivity rate to sparfloxacin and levofloxacin; a relatively stable low resistance rate and a high sensitivity rate to azithromycin were achieved only after 2011; the resistance rate and sensitivity rate to erythromycin and roxithromycin fluctuated greatly.

Objective To analyze the rate and distribution of positive provocative tests in patients with inducible urticaria,and to investigate the role of provocative tests in the etiological diagnosis of chronic urticaria.Methods Among patients who visited the special clinic for urticaria in the Department of Dermatology of the Third Affiliated Hospital,Sun Yat-sen University from January 2016 to December 2017,127 patients with suspected inducible urticaria were selected,and underwent 6 provocative tests for inducible urticaria,including delayed pressure urticaria provocative test (DPUPT),symptomatic dermographism provocative test (SDPT),vibratory angioedema provocative test (VAEPT),cold urticaria provocative test (CUPT),heat urticaria provocative test (HUPT),and aquagenic urticaria provocative test (AUPT).Statistical analysis was carried out by chi-square test for comparison of positive rates between male and female patients.Results Among the 127 patients with suspected inducible urticaria,106(83.46％) showed one or more positive provocative tests.The positive rate of SDPT was the highest (79.53％,101/127),followed by HUPT (22.05％,28/127) and CUPT (9.45％,12/127).The positive rate of HUPT was significantly higher in female patients (30.14％,22/73) than in male patients (11.11％,6/54;X2 =4.301,P ＜ 0.05).The patients with positive DPUPT,VAEPT and AUPT all showed positive SDPT responses.Among the 12 patients with positive CUPT reactions,11 showed positive SDPT responses.Among the 28 patients with positive HUPT reactions,26 showed positive SDPT responses.Of the 48 patients with one or more positive non-SDPT provocative tests,the patients with 2 positive non-SDPT provocative tests accounted for 18.75％ (9/48).Conclusion Provocation tests for inducible urticaria are of great clinical significance for the etiological diagnosis of chronic urticaria.

Taking the course's characteristics and advantages into account, this study explores the systematic implementation of standardized teaching rounds in the clinical probation sessions of the Dermatology and Venereology course , and evaluates its effect by analyzing the cases of 125 medical students from grade 2015 of Sun Yat-sen University . The results showed that the implementation of standardized teaching rounds has positive effect on the course.

Clinical final examination is an important link in the standardized training of residents in dermatology and quantification of evaluation indicators is one of the important parameters. In this study, the scores of clinical examinations of six candidates who participated in standardized training of residents in dermatology of Sun Yat-Sen University in June 2019 were taken as examples to explore the quantitative indicators of standardized and multi-station clinical final examinations. The indicators contained four stations and five links: skin pathological reading, skin biopsy, medical history collection and physical examination, medical record writing, and comprehensive questioning, which covered the main contents of the standardized training outline of residents in dermatology. Each evaluation indicator was refined and quantified. Finally, heuristic ideas were put forward, including a wider range of standardized and multi-station clinical examinations, introduction of new examination places, and utilization of information technology.