Objective To investigate the epidemiological characteristics and molecular transmission mechanism of the colistin resistance gene mcr-1 in food animal-derived Escherichia coli in Hanzhong, Shaanxi Province, and to grasp the prevalence of mcr-1 positive Escherichia coli in Hanzhong, in order to offer the empirical evidence for the prevention and management of disseminating the mcr-1 colistin resistance gene in both community and hospital settings. Methods From November 2019 to May 2020, frozen whole chicken carcasses and frozen raw ground pork were randomly sampled from seven major supermarkets in Hanzhong, Shaanxi Province, for the isolation and identification of Escherichia coli. The mcr-1 gene was detected using PCR analysis, and the drug susceptibility of mcr-1-positive strains was assessed using the broth dilution method. Whole genome sequencing, S1-pulsed field gel electrophoresis (PFGE), and Southern blot were used to locate the mcr-1 gene. Results Out of 159 samples randomly collected from seven different supermarkets, 77 Escherichia coli strains were isolated, and 11 strains carrying the mcr-1 gene were detected, with a positive rate of 14.29%. All 11 mcr-1-positive strains were multidrug-resistant, with a minimum inhibitory concentration (MIC) for colistin ≥2 mg/L (11/11). They exhibited a 100.00% resistance rate to ampicillin, streptomycin, tetracycline, and chloramphenicol (11/11), and all produced extended-spectrum beta-lactamases (ESBLs). The strains exhibited susceptibility to carbapenems and cefoxitin but had a 90.91% resistance rate to quinolones ciprofloxacin and levofloxacin. The mcr-1 gene was located on plasmids in 10 of the mcr-1-positive strains, with plasmid sizes approximately 60 kb and 220 kb. The 11 mcr-1-positive Escherichia coli strains belonged to 9 different sequence types (STs), including one previously unidentified ST. Besides carrying the colistin resistance gene mcr-1, all isolates possessed at least one ESBLs gene, predominantly blaCTX-M-55 (8/11, 72.73%). The plasmid types harboring mcr-1 were predominantly IncI2 (5/11, 45.45%) and IncHI2 (5/11, 45.45%), with one strain having mcr-1 located on the chromosome. Conclusions The mcr-1-positive Escherichia coli detected in this study are all multidrug-resistant and produce ESBLs, predominantly blaCTX-M-55. The mcr-1 gene can be transmitted through plasmid and chromosome.

OBJECTIVE：To provide reference for clinical empirical treatme nt of non-fermentative Gram-negative bacilli （NFGNB）infection. METHODS ：All kinds of clinical specimens were collected from Jan. 2010 to Dec. 2019 in a tertiary hospital from Hanzhong city of Shaanxi province ；the distribution and drug resistance of NFGNB were analyzed retrospectively. RESULTS ： A total of 26 386 strains of pathogenic bacteria were detected in the hospital during 2010-2019，including 4 077 strains of NFGNB （15.45％），mainly from patients ≥60 years old （1 836 strains，45.05％）. During the 10 years，the detection rate of NFGNB decreased from 20.14％ in 2010 to 15.36％ in 2019 （P＜0.001）. Acinetobacter baumannii （1 359 strains），Pseudomonas aeruginosa （1 269 strains），Stenotrophomonas maltophilia （447 strains） and Burkholderia cepacia （351 strains） were main pathogens. The detected NFGNB mainly came from hospitalized patients （4 001 strains），and most of them were found in ICU （17.05％），neurosurgery department （14.52％），respiratory department （12.41％），and respiratory tract （66.69％），secretion （7.80％）specimens. The detection rates of A. baumannii and P. aeruginosa in oncology department ，blood specimens and urine specimens showed an overall upward trend ，while the detection rates in ICU of the hospital showed a downward trend （P＜0.05）； the detection rate of P. aeruginosa in neurosurgery department showed an upward trend （P＜0.05），and that of A. baumannii in respiratory department showed an upward trend （P＜0.05）. The resistance rate of A. baumannii to carbapenems increased from about 10％ in 2010 to about 75％ in 2019，and the guyh3201@163.com resistance rate to cephalosporins exceeded 78％. The resistance rates of P. aeruginosa to imipenem and me ropenem were lower than 35％ and 30％ respectively，and the trend of drug resistance did not change significantly （P＞0.05）；the resistance rates to 12 kinds of clinically commonly used antibiotics as piperacillin and aztreonam were lower than 40％. The resistance rate of S. maltophilia to compound sulfamethoxazole showed a decreasing trend （P＜0.001），and the resistance rate to ceftazidime was high （54.70％-74.10％）. The resistance rates of B. cepacia to compound sulfamethoxazole，meropenem and ceftazidime showed a downward trend （P＜0.01），and were lower than 15％ after 2014. CONCLUSIONS：Although the detection rate of NFGNB in our hospital showed a downward trend ，the multi-drug resistance and pan-drug resistance of A. baumannii are serious ，and the resistance rate to carbapenems is increased. Sensitive drugs such as cefoperazone/sulbactam，amikacin，levofloxacin and ceftazidime should be selected for NFGNB infection according to the results of drug sensitivity tests.

Objective To study the bibenzyls and phenanthrenes from Arundina graminifolia.Methods The compounds were extracted by 95％ alcohol and isolated by column chromatography on silica gel and Sephadex LH-20.Their structures were identified by spectroscopic analysis (1H NMR and13CNMR).Results Eleven compouds were obtained and identified as batatasin Ⅲ (1),arundinanin (2),2,8-dihydroxy-4,7-dimethoxy-9,10-dihydrophenanthrene (3),shancidin (4),arundinan (5),isoshancidin (6),erianthridin (7),lusianthridin (8),eulophiol (9),flavanthrin (10),orchinol (11).Conclusion Compounds 3,7,9 were isolated from this plant for the first time.