Molecular and clinical characteristics of carbapenem-resistant Enterobacteriaceae isolates collected at a tertiary hospital in northern China.

BACKGROUND: Carbapenem-resistant Enterobacteriaceae (CRE) represent a severe public health problem. METHODS: In a tertiary hospital in northern China, 169 non-duplicated clinical CRE strains were analyzed by species identification, in vitro antibiotics sensitivity test, carbapenemase gene detection and genetic sequence typing. RESULTS: The CRE strains showed high resistance to most clinical antimicrobials. Enterobacter cloacae and Escherichia coli isolates mainly carried blaNDM, and Klebsiella pneumoniae isolates mainly carried blakpc. ST11 was the most common type in Klebsiella pneumoniae, and ST70 was the new emerging sequence type (ST) in Enterobacter cloacae. CONCLUSIONS: The CRE strains isolated in northern China showed multidrug-resistant phenotypes, and the new emergence of ST70 Enterobacter cloacae should be closely supervised.

Epidemiological characteristics and molecular evolution mechanisms of carbapenem-resistant hypervirulent Klebsiella pneumoniae.

Carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP), a type of Klebsiella pneumoniae (KP) that exhibits hypervirulence and carbapenem resistance phenotypes, can cause severe infections, both hospital- and community-acquired infections. CR-hvKP has brought great challenges to global public health and is associated with significant morbidity and mortality. There are many mechanisms responsible for the evolution of the hypervirulence and carbapenem resistance phenotypes, such as the horizontal transfer of the plasmid carrying the carbapenem resistance gene to hypervirulent Klebsiella pneumoniae (hvKP) or carbapenemase-producing Klebsiella pneumoniae (CRKP) acquiring a hypervirulence plasmid carrying a virulence-encoding gene. Notably, KP can evolve into CR-hvKP by acquiring a hybrid plasmid carrying both the carbapenem resistance and hypervirulence genes. In this review, we summarize the evolutionary mechanisms of resistance and plasmid-borne virulence as well as the prevalence of CR-hvKP.

[Characteristics of PM2.5 Pollution in Beijing During the Historical Period of the 2022 Olympic Winter Games].

Based on the dataset derived from January to March between 2015 and 2021 in Beijing, the PM2.5 pollution characteristics and its potential source regions during the historical period of the Beijing 2022 Olympic Winter Games and Paralympic Winter Games were investigated. From 2015 to 2018, both the number of severely polluted days (daily average ρ(PM2.5)>75 µg·m-3) and the average PM2.5 concentrations during severe pollution episodes decreased significantly in the period of January to March. While, neither variable has changed obviously since 2018. On average, severely polluted days occurred 23 times in each year between 2018 and 2021 during the period of January to March, and the average of ρ(PM2.5) was approximately 120.0 µg·m-3 during such polluted days. From January to March in 2015-2021, the severely polluted event with more than 5 consecutive polluted days occurred 2-3 times in each year, and the severest one lasted 8 d. During the historical period of the Beijing 2022 Olympic Winter Games, severely polluted days took place 2-9 d every year. The large quantities of fireworks during the Spring Festival maybe one of important primary sources of the PM2.5. The number of severely polluted days during the historical period of the Paralympic Winter Games ranged from 1 to 5 d, except for 2021 with 9 d owing to the frequent stagnant weather condition. The PM2.5 chemical composition was dominated by secondary species on severely polluted days during the historical period of the Beijing 2022 Olympic Winter Games and Paralympic Winter Games. Nitrate accounted for 46% of the measurable chemical components of PM2.5 during severe pollution events in 2020, which was remarkably higher than that during clean days in the same year (11%). The mass fraction of SO42- ranged from 12% to 19% in 2018-2020, indicating that the contribution of sulfate was much less, but cannot be ignored. The main potential source regions of PM2.5 in Beijing during the period concerned in this study were central and western Inner Mongolia, Hebei Province, Tianjin City, Shanxi Province, Shaanxi Province, central and western Shandong Province, and northern Henan Province.

Net benefit of routine urine parameters for urinary tract infection screening: a decision curve analysis.

BACKGROUND: Whether routine urinary analysis has a net benefit for urinary tract infection (UTI) screening is unclear. METHODS: Using the laboratory information system (LIS), we retrospectively extracted the data of urine culture and routine analysis between January 2017 and April 2017. Receiver operating characteristic (ROC) curve, logistic regression model, net reclassification improvement (NRI) and integrated discrimination improvement (IDI) were used to estimate the screening performance of routine urinary analysis. Decision curve analysis (DCA) was used to estimate the net benefit of routine urinary analysis. RESULTS: A total of 927 specimens with 156 UTIs were included in the present study. The area under ROC curves (AUCs) of white blood cells (WBCs) and bacteria were 0.729 and 0.836, respectively. The logistic regression model incorporating WBCs, bacteria and nitrite together had an AUC of 0.851, which is significantly higher than that of WBCs. NRI and IDI analyses also indicated that WBCs, bacteria and nitrite, when used together, had better a screening performance than each single test alone. DCA revealed that 0.08 net benefit can be obtained for bacteria and the model, while the net benefit of WBCs is limited. CONCLUSIONS: WBCs, bacteria and nitrite, when used together, can significantly improve the efficiency for UTI screening. Bacteria and the model incorporating WBCs, bacteria and nitrite have a net benefit in UTI screening, while the net benefit of WBCs, when used alone, is limited.

[Quercetin enhances the anti-leukemic effect of adriamycin].

This study was purposed to explore the anti-leukemic mechanism of quercetin (Que) in vivo and it enhancing chemotherapeutic effect of adriamycin (ADR) by establishing the quercetin-treated P388 transplanted nude mouse model. The P388 leukemic cells in logarithmic growth phase were taken and injected subcutaneously into BALB/c nude mice so as to establish the leukemia-transplanted nude mouse model. The model mice were treated by quercetin, ADR and their combination, and the survival changes of model mice were observed, the hemogram and peripheral blood cell count examination were performed regularly; the cell cycle was detected and the influence of quercetin on cell proliferation was analyzed by flow cytometry; the caspase-3 protein expression level was detected by ELISA; the mRNA and protein changes of NF-κB, BCL-2, BAX were measured by real-time quantitative flourascence PCR and Western blot respectively. The results indicated that the quercetin and adriamycin could significantly prolong the survival of P388 leukemia nude mice, and their combination displayed significantly prolonged effect. Quercetin and adriamycin alone or in their combination could reduce the ratio of G0/G1 phase in mice, the cell ratio in S phase and G2/M phase increased, and the effects of the combination group were more significant than that of the single agent groups. Quercetin could activate caspase-3 and promote leukemic cell apoptosis. Meanwhile, quercetin could down-regulate the expression of BCL-2 and NF-κB gene, and up-regulate the expression of BAX gene. It is concluded that through modulating the expression of apoptosis-related genes, the quercetin can inhibit leukemia cell proliferation, promote apoptosis, and enhance the chemotherapeutic effects of adriamycin. These results provide some valuable data for further research and development of quercetin as a new and effective anti-leukemic drug.

[Risk factors for acquired multidrug-resistant Acinetobacter baumannii colonization in respiratory intensive care unit].

OBJECTIVE: To determine the risk factors for respiratory intensive care unit (RICU)-acquired colonization of multidrug-resistant Acinetobacter baumannii (MDR-AB). METHODS: From January 2010 to June 2011, active screening was performed to define patients with RICU-acquired colonization of MDR-AB. And environment surveillance was carried out and patient data were collected. Logistic regression was applied to identify the risk factors of RICU-acquired colonization of MDR-AB. RESULTS: Active screening for MDR-AB was performed for 110 patients in RICU and 50 patients turned out to be positive. After eliminating 3 input positive patients, the RICU-acquired colonization rate of MDR-AB was 43.9% (47/107). The environmental contaminated rate of MDR-AB was 66.0% (31/47) for 47 positive patients and 33.9% (19/56) for 56 negative ones (χ(2) = 10.494, P < 0.01). Five risk factors were associated with the colonization of MDR-AB through univariate analysis: consciousness disturbance, use of carbapenems, nasal feeding tube, endotracheal intubation and mechanical ventilation (all P < 0.05). The Logistic regression equation contained 3 risk factors of conscious disturbance, use of carbapenems and mechanical ventilation (OR = 3.412, 3.211, 3.002; 95% CI: 1.165 - 9.992, 1.117 - 9.233, 1.101 - 8.182). CONCLUSION: Three risk factors are independently associated with the RICU-acquired colonization of MDR-AB: consciousness disturbance, use of carbapenems and mechanical ventilation.

[Correlation factor analysis of pan-drug resistant Acinetobacter baumannii strains in acquired infections].

OBJECTIVE: To explore the clinical factors, drug resistance and molecular epidemiology homologous characteristics of pan-drug resistant Acinetobacter baumannii (PDRAB) in acquired infections and analyze the correlation factor between epidemic characteristics and acquired infections. METHODS: A total of 60 PDRAB strains from nine acquired infections and related clinic data were collected from January 2009 to January 2011. The drug-resistant phenotype was tested by disk diffusion methods. The isolate identification and homology were studied by automation repetitive-element sequence-based (REP)-PCR typing platform from genes and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-TOF MS) from proteins. RESULTS: All strains were resistant to 12 antibiotics except 2 strains to imipenem and meropenem. The strains in this study were divided into 12 types (A-L) by REP-PCR. And 60 strains were also clustered to a-e types by MALDI-TOF-TOF MS. Compared with MALDI-TOF-TOF MS, REP-PCR tended to be more accurate. Breathing machine carriage and cross transmission were the main reasons for a major epidemic outbreak at department of pulmonary medicine from July 2009 to October 2009. Hand transmission of medical care personnel was a key factor for SICU 2010 January to February. The contamination and transmission to environment of PDRAB in nasal pharynx or respiratory tract by superspreader were the main reasons for the other 7 epidemic outbreaks. Department of emergency medicine was the source of acquired infections. CONCLUSION: The key control measures of acquired infections are early identification and isolation of spreader, environment and instrument disinfection, hand washing and rational uses of antibiotics. MALDI-TOF-TOF MS will become a preferred tool of identification and classification of microorganisms because of its simple operation, affordable price and handling rapidity.

Catalytic highly enantioselective alkylation of aldehydes with deactivated grignard reagents and synthesis of bioactive intermediate secondary arylpropanols.

Because of the high reactivity of Grignard reagents, a direct, highly enantioselective Grignard reaction with aldehydes has rarely been disclosed. In this report, Grignard reagents were introduced with bis[2-(N,N'-dimethylamino)ethyl] ether (BDMAEE) to effectively deactivate their reactivity; thus, a highly enantioselective alkylation of aldehydes with Grignard reagents resulted from catalysis by (S)-BINOL-Ti(O(i)Pr)(2). It is thought that BDMAEE chelates the in situ generated salts MgBr(2) from a Schlenk equilibrium of RMgBr and Mg(O(i)Pr)Br from transmetalation of RMgBr with Ti(O(i)Pr)(4). The Mg salts can actively promote the undesired background reaction to give the racemate. The chelation definitely inhibits the catalytic activity of the Mg salts, suppresses the unwanted background reaction, and enables the highly enantioselective addition catalyzed by (S)-BINOL-Ti(O(i)Pr)(2). Consequently, the Mg salt byproducts were not removed, less Ti(O(i)Pr)(4) than RMgBr was used, and extremely low temperature was avoided in this catalytic asymmetric reaction in comparison with the research disclosed before. Various alkyl Grignard reagents were investigated in the asymmetric addition, and (i)BuMgBr resulted in the highest enantioselectivity, >99%. Furthermore, important intermediate secondary arylpropanols for chiral drug synthesis were effectively synthesized with high enantioselectivity, up to 97%, in one step.

Highly catalytic asymmetric addition of deactivated alkyl grignard reagents to aldehydes.

Generally used and highly reactive RMgBr reagents were effectively deactivated by bis[2-(N,N-dimethylamino)ethyl] ether and then were employed in the highly enantioselective addition of Grignard reagents to aldehydes. The reaction was catalyzed by the complex of commercially available (S)-BINOL and Ti(O(i-)Pr)(4) under mild conditions. Compared with the other observed Grignard reagents, alkyl Grignard reagents showed higher enantioselectivity and they achieved >99% ee.

Protective effect of propofol against intracerebral hemorrhage injury in rats.

The neuroprotective effect of propofol against intracerebral hemorrhage (ICH) in rats was investigated. ICH was induced in rats by infusion of collagenase (Type VII) 0.5 U (1 U x microL(-1)) into the left caudate nucleus. Three doses of propofol were given intraperitoneally (i.p.) 10 min before collagenase infusion. Effects of propofol on neurological behavioral scores, brain water content (BWC), activity of superoxide dismutase (SOD) and content of malondialdehyde (MDA) in brain tissue, expression level of caspase-3 were studied. In propofol groups (30 and 100 mg x kg(-1)), the neurological behavioral score, BWC and the content of MDA were significantly lower than those in ICH group (P < 0.05, P < 0.01), whereas the activity of SOD was higher than that in ICH group (P < 0.05). Meanwhile, propofol (15, 30, and 100 mg x kg(-1)) inhibited caspase-3 expression in dose-dependent manner (r = 0.877). Brain damages caused by ICH in rats can be alleviated by propofol, which mechanism might be attributed to its antioxidant activity.