Objective To investigate the antimicrobial resistant mechanisms of high level carbapenem resistant Klebsiella pneumoniae infection of burn patients .Methods A retrospective study was conducted on totally 18 non-repetitive high level CR-KP which were isolated from burn patients hospitalized between July 2014 and June 2015.MIC of antibiotics were determined by using the GN 13 cards and agar dilution method.The specific PCR and DNA sequence analysis were performed to confirm the β-lactamase type.Plasmid conjugation transfer experiments and southem hybridization were applied to study the mode of carbapenem resistance transmission .Outer membrane proteins ( Omps) were isolated and examined by PCR and ( sodium dodecyl sulfate polyacrylamide gel electrophores ) SDS-PAGE.Pulsed-field gel electrophoresis( PFGE ) and Multilocus sequence typing ( MLST ) was used to determine the genotypes . Results Susceptibility of antimicrobial agents indicated that all these strains with multiple drug resistance . The resistance rate to piperacillin/tazobactam, ceftriaxone, levofloxacin, ciprofloxacin, gentamicin, tobramycin, cefotetan, ceftazidime, cefepime, aztreonam, imipenem, and meropenem was 100％ (18/18).Moreover, the resistance rate of CR-KP isolates to amikacin was 72.2％ ( 13/18 ) , compound sulfamethoxazole was 61.1％(11/18), tigecycline was 0％(0/18).Conjugation study with Escherictda coli J53 resulted in the transfer of significant reduced carbapenem susceptibility from donors (MICs increased at least 8-fold).By PCR, eighteen strains of Klebsiella pneumoniae carried NDM-1 gene, 5 strains carried KPC-2 gene.The blaNDM-1 was transferable by plasmids.Southern blot hybridization indicated that the blaNDM-1 gene was located on plasmid in size of 46 kb.The plasmid belonged to incompatibility group IncX 3.Seven types of CR-KP were detected by PFGE.In addition, MLST assigned them to sequence type ( ST)11, ST395, ST17, ST37, ST263, ST14 and ST76 types.SDS-PAGE and ompK35/36 genes sequence analysis of Omp indicated that there was absence of outer membrane proteins OmpK 36 in ST11, ST395, ST37 strains.However, the other STs strains expressed lower quantities of OmpK 36.Conclusions High level carbapenem resistance in K.pneumoniae causing infection in burn patients is attributable to production of plasmid-mediated metallo· β-laetamase NDM-1 combined with porin OmpK36 deficiency or low expression .The K.pneumoniae with NDM-1 and KPC-2 carbapenemase were detected .

Objective: The consistency of 24-hour oropharyngeal Dx-pH monitoring and proton pump inhibitor(PPI) test in the diagnosis of laryngopharyngeal reflux disease (LPRD) was investigated. Methods: Sixty patients with laryngopharyngeal reflux (LPR) related symptoms who had never received PPI treatment were assessed by reflux symptom index (RSI) and reflux finding score (RFS) between October 2017 and October 2018, including 28 males and 38 females, aged from 16 to 72 years, with a medium age of 38 years. Prior to treatment, all patients were evaluated with 24 hours oropharyngeal Dx-pH monitoring(Restech). After empiric therapy with PPI twice-daily for 8 weeks, the efficacy was evaluated according to posttreatment RSI score.The data was analysed with Kruskal-Wallis test, Student Newman Keuls test and consistency check. Results: (1)Among all 60 patients,13 patients (21.7%) had pathologic Ryan score and all resulted responsive to PPI;27 patients (45.0%) with a negative Ryan score were unresponsive to PPI; 20 patients (33.3%) despite a negative Ryan score resulted responsive to PPI therapy. Considering responsiveness to PPI therapy as the gold standard for the diagnosis of LPRD, the sensitivity, specificity, positive predictive value and negative predictive value of Ryan score were 39.4%, 100%, 100% and 57.4% respectively. The Kappa value was 0.369 (P<0.01). (2)Among 34 patients (56.7%) with positive Dx-pH results (24-hour oropharyngeal acid reflux events≥ 3 times), 29 patients were positive and 5 patients were negative in PPI test. Among 26 patients with negative Dx-pH results (24-hour oropharyngeal acid reflux events<3 times), 4 patients were positive and 22 patients were negative in PPI test. Considering responsiveness to PPI therapy as the gold standard for the diagnosis of LPRD, the sensitivity, specificity, positive predictive value and negative predictive value of 24-hour oropharyngeal acid reflux events were 87.9%, 81.5%, 85.3% and 84.6% respectively. The Kappa value was 0.696(P<0.01). Conclusions There is a positive correlation between 24-hour oropharyngeal Dx-pH monitoring positive results (24-hour oropharyngeal acid reflux events≥3 times) and PPI test in the diagnosis of LPRD. The 24-hour oropharyngeal Dx-pH monitoring can be a promising tool for the diagnosis of suspected LPRD patients, and more sensitive and accurate Dx-pH diagnostic index will be required in the clinic.