2016 Vol. 29, No. 2
2016, 29(2): 85-90. doi: 10.3967/bes2016.009
ObjectiveTo gain greater insight into the prevalence drug resistant profiles ofM. abscessus from a general hospital in Beijing, China. MethodsPartial gene sequencing of16S,hsp65,and rpoB were used to distinguish the species of NTM isolates. All strains identified asM. abscessus were further enrolled in the drug susceptibility testing by using broth microdilution method. ResultsWe found thatM. avium complex was the most frequent NTM organism, accounting for 54.1%(33/61) of all isolates. Behind MAC, the second most common organisms were M. abscessus (22 out of 61, 36.1%). Average rates of resistance were 4.5% for AMK, 9.1% for LZD, and 13.6% for CLA, respectively. In contrast, resistance to LEV (17/22, 77.3%), IMI (9/22, 40.9%), and SMX (10/22, 45.5%) was noted in more than 40% ofM. abscessusisolates. DNA sequencing revealed that all the CLA-resistant isolates harbored nucleotide substitutions in position 2058 (1/3, 33.3%) or 2059 (2/3, 66.7%) of 23S rRNA. ConclusionIn conclusion, our data demonstrated thatM. intracellulare andM. abscessuswere the most common NTM species in the general hospital of Beijing.CLA, AMK, LZD showed promising activity, whereas LEV, IMI, and SMX exhibited poor activity againstM. abscessus in vitro.
2016, 29(2): 91-98. doi: 10.3967/bes2016.010
ObjectiveTo investigatetheprevalence of primary drug-resistant tuberculosis (TB) and associated risk factors in China.We also explored factors contributing tothe transmission of multidrug-resistant tuberculosis (MDR-TB). MethodsA total of 2794 representative,Mycobacterium tuberculosis isolates from treatment-naive patients were subjected to drug susceptibility testing, and risk factors for drug-resistant TBwere analyzed. We also analyzed MDR-TB strain sublineages, drug-resistance-conferring mutations, and risk factors associated with clustered primary MDR strains. ResultsAmong 2794Mycobacterium tuberculosis isolates from treatment-naive patients, the prevalence of any resistance to first-line drugs was 33.2%andthe prevalence of MDR-TB was 5.7%. We did not find any risk factors significantly associated with resistance to first-line drugs.The93 primary MDR-TB isolates were classified into six sublineages, of which, 75 (80.6%) isolates were the RD105-deleted Beijing lineage.The largest sublineage included 65 (69.9%) isolates with concurrent deletions of RD105, RD207, and RD181.Twenty-nine (31.2%) primary MDR strains grouped in clusters;MDR isolates in clusters were more likely to have S531LrpoBmutation. ConclusionThis study indicates that primary drug-resistantTBand MDR-TBstrains are prevalent in China,and multiplemeasures should be taken toaddress drug-resistant TB.
The Survey ofCronobacterspp. (formerlyEnterbacter sakazakii) in Infant and Follow-up Powdered Formula in China in 2012
2016, 29(2): 99-106. doi: 10.3967/bes2016.011
ObjectiveTo determineCronobacterspp.contamination in infant and follow-up powdered formula in China. MethodsAll of 2282 samples were collected from theretailmarkets in China from January 2012 to December 2012, and analyzed forCronobacter spp.by theChineseNationalFood Safety Standard. Characterization of the isolates was analyzed by pulsed-field gel electrophoresis (PFGE) withXbaI and SpeI restriction enzymes. ResultsCronobacterspp. strains were isolated from 25 samples, and the positive rates ininfant powdered formulas and follow-up powdered formulas were 0.90% (10/1011) and 1.18% (15/1271), respectively. Analysis of variable data regarding different purchasing store formats, seasonality, and production locations as well as comparison of infant versus follow-up formulas did not reveal statistically significant factors. During the sampling period, one of six surveillance zones did exhibit a statistically significant trend towards higher positive rate. PFGE characterization ofCronobacterspp.to elucidate genetic diversity revealed only three pairs ofCronobacterspp.out of 25 having the same PFGE patterns. ConclusionThe current investigation indicated a lower positive rate ofCronobacterspp.in the powdered formula in China.This evidence suggested contamination originating from multiple different sources during the manufacturing process.
The Cellular Toxicity of PM2.5 Emitted from Coal Combustion in Human Umbilical Vein Endothelial Cells
2016, 29(2): 107-116. doi: 10.3967/bes2016.012
ObjectiveTo explore the relationship between different components offineparticulate matter (PM2.5) emitted from coal combustion and their cytotoxic effect in the vascular endothelial cells. MethodsCoal-fired PM2.5was sampled using a fixed-source dilution channel and flow sampler. The sample components were analyzed by ion chromatography and inductively coupled plasma atomic emission spectroscopy(ICP-AES). The PM2.5suspension was extracted using an ultrasonic water-bath method and thenhuman umbilical vein endothelial cells (EA.hy926) were treated withvarious concentrations of the PM2.5 suspension. Cell proliferation,oxidativeDNA damage, and global DNA methylation levelswere used to measurethe cellulartoxicity of PM2.5emitted fromcoalcombustion. ResultsComparedtoothertypesof coal-fired PM2.5preparations,thePM2.5 suspension from Yinchuan coal had the highest cytotoxicity.PM2.5 suspension from Datong coal hadthe highest toxic effectwhile that fromYinchuan coal had the lowest.Exposure to coal-fired PM2.5 from Jingxi coalresulted inlower 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels. At the same dose, PM2.5 emitted from coal combustion could produce more severeDNAimpairmentcompared to that produced by carbon black.Cell survival rate was negatively correlated with chloride and potassiumionscontent.The5-methylcytosine(5-mC) level waspositively correlated withMnandnegatively correlated withZn levels.The 8-OHdG% level was positively correlated withboth MnandFe. ConclusionPM2.5 emitted from coal combustion can decrease cell viability, increase global DNA methylation, and causeoxidativeDNA damage inEA.hy926 cells. Metalcomponentsmay be important factors that influence cellular toxicity.
Cadmium Activates Reactive Oxygen Species-dependent AKT/mTOR and Mitochondrial Apoptotic Pathways in Neuronal Cells
2016, 29(2): 117-126. doi: 10.3967/bes2016.013
ObjectiveTo examine the role of Cd-induced reactive oxygen species (ROS) generation in the apoptosis of neuronal cells. MethodsNeuronal cells (primary rat cerebral cortical neurons and PC12cells) were incubated with or without Cd post-pretreatment with rapamycin (Rap) or N-acetyl-L-cysteine (NAC). Cell viability was determined by MTT assay, apoptosis was examined using flow cytometry and fluorescence microscopy, and the activation of phosphoinositide 3'-kinase/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) and mitochondrial apoptotic pathways were measured by western blotting or immunofluorescence assays. ResultsCd-induced activation of Akt/mTOR signaling, including Akt, mTOR,p70 S6 kinase (p70 S6K), and eukaryotic initiation factor 4E binding protein 1(4E-BP1). Rap, an mTOR inhibitor and NAC, a ROS scavenger, blocked Cd-induced activation of Akt/mTOR signaling and apoptosis of neuronal cells. Furthermore, NAC blocked the decrease of B-cell lymphoma 2/Bcl-2 associated X protein (Bcl-2/Bax) ratio, release of cytochrome c, cleavage of caspase-3 and poly(ADP-ribose) polymerase (PARP), and nuclear translocation of apoptosis-inducing factor(AIF)and endonuclease G (Endo G). ConclusionCd-induced ROS generation activates Akt/mTOR and mitochondrial pathways, leading to apoptosis ofneuronal cells. Our findings suggest that mTOR inhibitors or antioxidants have potential for preventing Cd-induced neurodegenerative diseases.
Bioremediation of Hexavalent Chromium Pollution by Sporosarcina saromensis M52 Isolated from Offshore Sediments in Xiamen, China
2016, 29(2): 127-136. doi: 10.3967/bes2016.014
ObjectiveCr(VI) removal from industrial effluents and sediments has attracted the attention of environmental researchers. In the present study, we aimed to isolate bacteria for Cr(VI) bioremediation from sediment samples and to optimize parameters of biodegradation. MethodsStrains with the ability to tolerate Cr(VI) were obtained by serial dilution and spread plate methods and characterized by morphology, 16S rDNA identification, and phylogenetic analysis. Cr(VI) was determined using the 1,5-diphenylcarbazide method, and the optimum pH and temperature for degradation were studied using a multiple-factor mixed experimental design. Statistical analysis methods were used to analyze the results. ResultsFifty-five strains were obtained, and one strain (Sporosarcina saromensisM52; patent application number: 201410819443.3) having the ability to tolerate 500 mg Cr(VI)/L wasselected to optimize the degradation conditions. M52 was found be able to efficiently remove 50-200 mg Cr(VI)/L in 24 h, achieving the highest removal efficiency at pH 7.0-8.5 and 35°C. Moreover, M52 could completely degrade 100 mg Cr(VI)/L at pH 8.0 and35 °C in 24 h. The mechanism involved in the reduction of Cr(VI) was considered to be bioreduction rather than absorption. ConclusionThe strong degradation ability ofS. saromensis M52 and its advantageous functional characteristics support the potential use of this organism for bioremediation ofheavy metal pollution.
2016, 29(2): 143-147. doi: 10.3967/bes2016.016