Fast dissemination of the mobilized colistin resistance (
mcr
) gene
mcr-1
in
Enterobacteriaceae
causes a huge threat to the treatment of severe infection. In the current report, a multiple cross displacement amplification (MCDA) coupled with the detection of amplified products by gold nanoparticles-based lateral flow biosensor (LFB) assay (MCDA-LFB) was established to identify the
mcr-1
gene with simpleness, rapidity, specificity, and sensitivity. The MCDA-LFB assay was performed at a isothermal temperature (63°C) for only 30 min during the amplification stage, and the reaction products were directly identified by using LFB which obtained the result within 2 min. The entire process of experiments, from templates extraction to result judging, was accomplished in <60 min. For the analytical specificity of this method, all of the 16
mcr-1
-producing strains were positive, and all of the non-
mcr-1
isolates produced the negative results. The sensitivity of
mcr-1
-MCDA-LFB assay was as little as 600 fg of plasmid DNA per reaction in pure culture, and approximately 4.5 × 10
3
CFU/mL (~4.5 CFU/reaction) in spiked fecal samples. Therefore, this technique established in the present study is suitable for the surveillance of
mcr-1
gene in clinic and livestock industry.
Association of HLA class II with multiple sclerosis (MS) has been widely studied in both Western and Oriental populations. However, such an association is not well documented in Chinese. The objective of this study was to examine the association between the susceptibility to conventional MS in Southern Chinese with HLA-DRB1,-DPB1 alleles and putative DRB1-DPB1 haplotypes. Genotyping of HLA-DRB1 and -DPB1 alleles was performed in 60 patients with conventional MS and 95 controls. Allele frequencies were compared between patients and controls to identify MS-associated alleles. Relative predisposing effect method was used to compare haplotype frequencies in patients and controls and to identify possible predisposing DRB1-DPB1 haplotypes, which were further examined for differences in haplotype carriage rates between the two groups. We found that the allele frequency of DRB1*1501 was not different between patients (18.3%) and controls (21.1%) (p = 0.837). In contrast, frequency of the DPB1*0501 allele was significantly higher in patients (90%) than in controls (67.4%) (odds ratio = 4.36, p = 0.0013, pcorr = 0.025). DRB1-DPB1 linkage haplotype in patients (8.33%) was significantly higher than in controls (0%) (p < 0.0001) and the carriage rate of this haplotype was significantly increased in patients (15%) as compared with controls (0%) (p = 0.00013, pcorr = 0.003). Combined, these results suggest that HLA-DRB1*1501 is not associated with susceptibility to conventional MS in Southern Chinese. Instead, both the DPB1*0501 allele and the DRB1*1602- DPB1*0501 haplotype are strong predisposing factors for conventional MS in this population. Our results establish that the HLA profiles of MS in Southern Chinese are distinct from other populations.
Escherichia coli sequence type 131 (ST131) is well known for its multidrug resistance profile. Carbapenems have been considered the treatment of choice for E. coli ST131 infections, and resistance to carbapenems is emerging due to the acquisition of carbapenemase-encoding genes. In this study, 45 carbapenem-resistant E. coli strains were collected in a hospital. The resistance mechanisms, plasmid profiles, and genetic relatedness of these strains were determined. Phylogenetic relationships between these strains were assessed by molecular profiling and aligned with patient clinical details. The genetic context of bla KPC−2 was analyzed to trace the potential dissemination of bla KPC−2. The 45 carbapenem-resistant E. coli ST131 strains were closely related. Initially prevalent only in a single ward, ST131 subsequently spread to other ward, resulting in a respiratory infection outbreak of carbapenem-resistant E. coli ST131. Eight of the 30 patients died within 28 days of the first isolation of E. coli ST131. The bla KPC−2positive plasmid profiles suggest that the carbapenem resistance was due to the acquisition by E. coli ST131 of transmissible plasmids pE0272_KPC and pE0171_KPC carrying bla KPC−2. Additionally, diverse multidrug resistance elements were transferred and rearranged between these plasmids mediated by IS26. Our research indicates that clinical attention should be paid to the importance of E. coli ST131 in respiratory infections and the spread of bla KPC-carrying E. coli ST131.
This study aimed to design a new method for rapid and accurate detection of carbapenemase phenotypes based on the simplified carbapenem inactivation method (sCIM). We evaluated the sensitivity and specificity of the method, called the rapid carbapenemase detection method (rCDM), for the detection of carbapenemase-producing Enterobacteriaceae and Pseudomonas aeruginosa. A total of 257 Enterobacteriaceae, 236 P. aeruginosa, and 20 Acinetobacter baumannii isolates were tested. Phenotypic evaluations were performed using rCDM, sCIM, and mCIM. For Enterobacteriaceae, the sensitivity of rCDM was 100% and the specificity was 99.6%. For P. aeruginosa, the sensitivity of rCDM was 97.4% and the specificity was 100%. Carbapenemase-producing A. baumannii were not detected by rCDM. The concordance rate of rCDM and sCIM for Enterobacteriaceae and P. aeruginosa was 99.8%, with the exception of one P. aeruginosa isolate that expressed the blaVIM−4 gene. The concordance rate of rCDM and mCIM for Enterobacteriaceae and P. aeruginosa was 100%. rCDM can be used to accurately detect carbapenemase-producing Enterobacteriaceae and P. aeruginosa in 5–6 h and is suitable for routine use in most clinical microbiology laboratories.
Postoperative adjuvant therapy with intra-arterial (131)I-lipiodol to hepatic resection of HCC significantly improves overall and disease-free survival rates and reduces recurrence rates. However, well-designed randomized trials are needed to arrive at conclusive evidence.
22Fast dissemination of the mobilized colistin resistance (mcr) gene mcr-1 in 23 Enterobacteriaceae causes a huge threat to the treatment of severe infection. In the current 24 report, a multiple cross displacement amplification (MCDA) coupled with the detection of 25 amplified products by gold nanoparticles-based lateral flow biosensor (LFB) assay 26 (MCDA-LFB) was established to identify the mcr-1 gene with simpleness, rapidity, 27 specificity and sensitivity. The MCDA-LFB assay was performed at a isothermal temperature 28 (63°C) for only 30 min during the amplification stage, and the reaction products were directly 29 identified by using LFB which obtained the result with 2 min. The entire process of 30 experiments, from templates extraction to result judging, was accomplished less than 60 min. 31 For the analytical specificity of this method, all of the 16 mcr-1-producing strains were 32 positive, and all of the non-mcr-1 isolates got the negative results. The sensitivity of 33 mcr-1-MCDA-LFB assay was as little as 600 fg of plasmid DNA per reaction in pure culture, 34 and approximately 4.5×10 3 CFU/mL (~4.5 CFU/reaction) in fecal samples spiked with 100 35 μl of strains. Therefore, this technique established in the present study is suitable for the 36 surveillance of mcr-1 gene in clinic and livestock industry. 37 38 3
A loop-mediated isothermal amplification assay combined with a nanoparticle-based lateral flow biosensor (LAMP-LFB) was established for the rapid and accurate detection of the mobilized colistin resistance gene (mcr-1), which causes the loss of colistin antibacterial efficacy in clinical treatments. The amplification stage of the assay was completed in 60 min at 63°C, and the reaction products could be visually detected by employing the LFB, which provided a fast (within 2 min) and objective method to evaluate the amplification results. The LAMP assay amplified the target sequences of mcr-1 with high specificity. In pure strains, the detection limit of the LAMP-LFB assay was 360 fg plasmid DNA/reaction, and in spiked feces samples the value was approximately 6.3×103 CFU/mL (~6.3 CFU/reaction), which was tenfold more sensitive than the PCR assay. The results show that the developed LAMP-LFB assay will be a worthy tool for the simple, rapid, specific, and sensitive detection of mcr-1 gene in clinical settings and resource-limited areas.
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