Resistance trends among clinical isolates in China reported from CHINET surveillance of bacterial resistance, 2005-2014.

With the aim of gathering temporal trends on bacterial epidemiology and resistance from multiple laboratories in China, the CHINET surveillance system was organized in 2005. Antimicrobial susceptibility testing was carried out according to a unified protocol using the Kirby-Bauer method or automated systems. Results were analyzed according to Clinical and Laboratory Standards Institute (CLSI) 2014 definitions. Between 2005 and 2014, the number of bacterial isolates ranged between 22,774 and 84,572 annually. Rates of extended-spectrum ß-lactamase production among Escherichia coli isolates were stable, between 51.7 and 55.8%. Resistance of E. coli and Klebsiella pneumoniae to amikacin, ciprofloxacin, piperacillin/tazobactam and cefoperazone/sulbactam decreased with time. Carbapenem resistance among K. pneumoniae isolates increased from 2.4 to 13.4%. Resistance of Pseudomonas aeruginosa strains against all of antimicrobial agents tested including imipenem and meropenem decreased with time. On the contrary, resistance of Acinetobacter baumannii strains to carbapenems increased from 31 to 66.7%. A marked decrease of methicillin resistance from 69% in 2005 to 44.6% in 2014 was observed for Staphylococcus aureus. Carbapenem resistance rates in K. pneumoniae and A. baumannii in China are high. Our results indicate the importance of bacterial surveillance studies.

[Study of the mechanism of cultured neuron injury mediated by nitric oxide during hypoxia and oxidative stress].

OBJECTIVE: To study the mechanisms of cultured neurons injury mediated by nitric oxide and free oxygen radical during hypoxia and oxidative stress. METHODS: The cultured newborn rat neurons were treated with hypoxia, H2O2 and pretreated superoxide dismutase (SOD) respectively. We examined the content of NO, malonaldehyde (MDA), lactate dehydrogenase (LDH) and SOD in cultured supernatant. RESULTS: Comparing with that of control group, the content of NO, LDH, MDA increased and the content of SOD decreased in hypoxia group and H2O2 group. The content between NO and SOD showed the negative correlation. Administration of 200 U/ml SOD before oxidative stress could efficiently decrease the release of NO, LDH and MDA in neurons. The content of NO, LDH and MDA manifested in positive correlation in each group. CONCLUSION: Hypoxia and oxidative stress increased NO production which strengthen neurons injury induced by free radical. SOD played an important role in elimination of free oxygen radicals and protecting neurons from injury by NO.