OBJECTIVE To investigate the distribution and characterization of the classes Ⅰ,Ⅱ and Ⅲ integrons on Stenotrophomonas maltophilia and clarify their influence on the bacterial drug-resistance.METHODS A multi-PCR assay using specific primers of int1,int2 and int3 was constructed to screen classes Ⅰ,Ⅱ and Ⅲ integrons.RESULTS Class Ⅰ integron was detected in 13.4% of clinical isolates,3 isolates harbored among class Ⅱ integrons. There was not been reported in abroad.CONCLUSIONS Classes Ⅰ and Ⅱ integrons could play an important role in causing the antibiotic multidrug resistance.

Objective:To evaluate the clinical efficacy of percutaneous intramyocardial septal radiofrequency ablation (PIMSRA) in the treatment of obstructive hypertrophic cardiomyopathy (HOCM) with mild septal hypertrophy.Methods:Forty-five HOCM patients with mild septal hypertrophy (the maximal left ventricular wall thickness is 15-19 mm) who were treated with PIMSRA between November 2016 to February 2021 in the Hypertrophic Cardiomyopathy Center of Xijing Hospital of Air Force Military Medical University were enrolled, and their clinical datas were collected and analyzed. The clinical symptoms and NYHA functional class before operation, 6 months and 1 year after operation were collected. Interventricular septum thickness, left ventricular outflow tract pressure gradient, left ventricular outflow tract diameter, mitral regurgitation, left ventricular systolic and diastolic function were evaluated by transthoracic echocardiography before operation, 6 months and 1 year after operation, intraoperative complications were monitored and recorded. Postoperative arrhythmias were monitored by routine 12 lead ECG and 24-hour ambulatory ECG.Results:All patients successfully completed PIMSRA procedure.No clinical adverse events such as death, bleeding and stroke occurred during and around the operation.No left bundle branch block, complete atrioventricular block and malignant arrhythmia occurred after the operation. All patients did not need permanent pacemaker implantation.NYHA functional class and clinical symptoms of patients were significantly improved after 6 months compared with values before operation (all P<0.001, respectively), it remained stable for 1 year after operation; Anterior interventricular septum, posterior interventricular septum, maximal left ventricular wall thickness all significantly decreased (all P<0.001, respectively), left ventricular outflow tract diameter widened ( P<0.001), continuous improvement 1 year after operation; left ventricular outflow tract gradient and provoked left ventricular outflow tract gradient all significantly decreased, mitral regurgitation decreased and SAM classification reduced after 6 months compared with values before operation (all P<0.001, respectively); left ventricular end-diastolic diameter widened and left atrial diameter decreased (all P<0.001, respectively), it remained stable for 1 year after operation. Left atrial volume index decreased ( P<0.001), with continuous improvement 1 year after operation; The ratio of early diastolic mitral valve velocity to early diastolic mitral annulus velocity (E/e′) decreased ( P=0.001), it remained stable for 1 year after operation. There were no significant differences in left ventricular end diastolic volume, left ventricular end systolic volume and left ventricular ejection fraction among the three groups (all P>0.05). Conclusions:PIMSRA is effective in the treatment of obstructive hypertrophic cardiomyopathy with mild ventricular septal hypertrophy.

Objective:To investigate the effect of percutaneous intramyocardial septal radiofrequency ablation (PIMSRA) guided by echocardiography on the Lown classification of ventricular arrhythmias in patients with hypertrophic obstructive cardiomyopathy (HOCM).Methods:A total of 85 patients with HOCM who received PIMSRA treatment at Xijing Hospital of Air Force Military Medical University from May 2017 to October 2019 were retrospectively selected. All patients underwent 24-hour Holter examinations before and 1 year after PIMSRA to obtain parameters related to Lown classification. The changes in Lown grades after PIMSRA were analyzed. The patients were divided into improved group and unimproved group according to whether there was significant improvement in Lowen′s grades, and the difference of the parameters related were compared. The influencing factors of the changes in Lown classification were analyzed.Results:Compared with before PIMSRA, there was a significant improvement in the Lown classification after PIMSRA ( P=0.001). The patients with Lown grade Ⅰ increased significantly ( P=0.001), and the patients with grade Ⅲ decreased significantly ( P=0.005). There were no significant changes in patients with Lown grades 0, Ⅱ, and Ⅳ (all P>0.05). The proportion of patients with family history of hypertrophic cardiomyopathy (HCM), the baseline Lown classes, the reduction rate of the maximum left ventricular wall thickness and the reduction rate of the provocative left ventricular outflow tract gradient (LVOTG) were higher in the improved group than the unimproved group (all P<0.05). Multivariate Logistic regression results showed that HCM family history ( OR=3.95, 95% CI=1.34-11.64, P=0.013), baseline Lown classes ( OR=2.01, 95% CI=1.25-3.22, P=0.004) and the reduction rate of the provocative LVOTG gradient ( OR=1.02, 95% CI=1.00-1.04, P=0.041) were independent factors of postoperative Lown classification improvement. Conclusions:The Lown classes of HOCM patients after PIMSRA is significantly improved.HCM family history, the baseline Lown classes, and the reduction rate of postoperative provocative LVOTG are independent influencing factors for the improvement of Lown grade.

Objective:To analyze the relationship between genotype and clinical phenotype of the MYH7-R453C mutation in five Chinese hypertrophic cardiomyopathy (HCM) families.Methods:A retrospective cohort study was conducted on 527 unrelated HCM probands who were first diagnosed at the First Affiliated Hospital of Air Force Medical University (Xijing Hospital) from February 2014 to July 2018, and the high-throughput whole exome targeted sequencing of 96 genes related to hereditary cardiovascular disease was performed on the probands. The probands carrying the MYH7-R453C mutation were screened out, and their family members carrying the mutation were verified using Sanger sequencing. Healthy individuals without family history of genetic diseases from the same period and ethnicity were recruited as controls. Clinical data such as echocardiography, 12-lead electrocardiogram, and cardiac magnetic resonance imaging of the probands and their family members were collected, and the correlation between patient genotype and clinical phenotype was analyzed. Endpoint or key events were recorded through hospital re-examination or telephone follow-up.Results:The MYH7-R453C mutation was detected in 5 HCM probands, and clinical data and genetic results of 20 family members, including probands, were collected. Among them, 13 carried the MYH7-R453C mutation, of which 12 were diagnosed with HCM, and one child (F1Ⅲ 5) experienced early changes of HCM. The seven family members who did not carry the MYH7-R453C mutation had normal echocardiograms and 12-lead electrocardiograms. Among the 12 patients diagnosed with HCM, 2 experienced (F2Ⅱ 7, F5Ⅰ 2) sudden cardiac death, 2 experienced (F1Ⅲ 1, F3Ⅲ 3) events of sudden cardiac death survival, 2(F1Ⅱ 2, F3Ⅱ 1) died from heart failure during the follow-up period. Combined with the initial visit and follow-up, 4 families (F1, F2, F3, F5) had a family history of sudden death, among which 3 families probands or multiple family members experiencing sudden death before the age of 30 and adverse outcomes such as implantation of implantable cardioverter-defibrillators after sudden death survival. Conclusions:In the five families with HCM carrying MYH7-R453C mutations, genotype is highly correlated with clinical phenotype, and patients have a high risk of sudden death and poor prognosis. Early diagnosis of individuals carrying the MYH7-R453C gene mutation, both within the patient′s family and in the patients themselves, is crucial for initiating early treatment, preventing sudden death, and assessing prognosis.