[Multi locus sequence typing and antibiotic susceptibility of extended-spectrum beta-lactamases producing Enterobacteriaceae in rural residents in villages with pig-breeding farms in Shandong province]

Objective: To analyze the antimicrobial resistance and multilocus sequence typing (MLST) results of extended-spectrum β-lactamase (ESBLs)-producing Escherichia coli in rural residents in villages with pig breeding farms in a county of Shandong province. Methods: Antimicrobial susceptibility testing was performed with agar dilution method by using 360 ESBLs-producing E. coli strains from fresh stool samples of rural residents in villages with pig breeding farms in a county of Shandong. PCR was conducted to amplify the CTX-M, TEM, SHV genes and capillary electrophoresis was used to screen positive strains in July, 2016. MLST was performed for molecular typing analysis, and eBURST v3.0 software was used for cluster analysis. Results: Among 360 strains of ESBLs-producing E. coli, the resistance rates to cefotaxime, tetracycline, trimethoprim-sulfamethoxazole and florfenicol were 100.0% (360/360), 82.2% (296/360), 81.1% (292/360) and 80.3% (289/360), respectively. The positive rate of CTX-M gene was 99.2% (357/360), in which the positive rate of CTX-M-9 was 35.6% (128/360) and the positive rate of CTX-M-1 was 24.4% (88/360). The positive rate of TEM gene was 26.9% (97/360). A total of 132 STs were identified through MLST. The predominant ST was ST10, accounting for 12.5% (45/360). Cluster analysis showed that CC10 was the most important clone group, including 39 ST clones, involving 148 strains (41.1%). Conclusions: The drug resistances of ESBLs-producing E. coli to cefotaxime, tetracycline, trimethoprim-sulfamethoxazole and flurfenicol are serious in this rural area. There is a small-scale clustering of CC10 and transmission mode from animals to humans might exist.

A novel Bruton tyrosine kinase gene variation was found in an adult with X-linked agammaglobulinemia during blood cross-matching prior to surgical operation

AIMS/OBJECTIVES

To investigate the underlying molecular mechanism of the patient's ABO typing discrepancy.

BACKGROUND

ABO typing discrepancy was frequently seen in patients due to different causes. In this study, ABO typing discrepancy was found in a 24-year-old man with arthralgia, whose forward ABO grouping was O and reverse ABO grouping was AB. Primary immunodeficiency disease was speculated in this patient, especially X-linked agammaglobulinemia (XLA).

METHODS

Immunoglobulins of all isotypes were detected using a specific protein analyser. Lymphocyte subgroups were analysed by flow cytometry. All 19 exons and boundaries of BTK gene were amplified by polymerase chain reaction (PCR), and all PCR products were sequenced by a DNA analyser. BTK protein in the leukocytes and platelets was detected by Western blot.

RESULTS

No B lymphocytes could be detected in the peripheral blood of the patient. A novel BTK gene variation, c.817G>T, in the exon 9 of BTK gene was discovered. No BTK protein expression could be detected in the leukocytes and platelets of the patient.

CONCLUSIONS

XLA could be occasionally discovered by ABO typing discrepancy in some cases because of the deficiency of reciprocal IgM anti-A and/or anti-B antibodies in the serum of the patient. Humoral immunodeficiency is one of the causes of ABO typing discrepancy.

Large magnetoresistance and large magnetothermopower effect in the Dirac material EuMn0.8Sb2

In this article, the structure, transport and magnetic properties were studied in details for EuMn_0.8Sb₂ crystals with the orthorhombic structure and Mn deficiencies. It was found that the temperature dependence of the resistivity exhibits a metallic behavior in the whole measuring temperature range, different from that in the crystals without Mn deficiencies. A large positive magnetoresistance (MR) (∼127% at 2 K and  ∼25% at 300 K, in 9 T field) was observed, which can be ascribed to the combination of semiclassical MR and quantum limit MR of Dirac electrons. We also observed the high mobility of the carriers and large magnetothermopower effect at low temperatures, and two magnetic transitions emerging at  ∼24 K and  ∼10 K, respectively, corresponding to the antiferromagnetic ordering and canted arrangement of the Eu moments. Our findings shed new light on the intrinsic properties of EuMn_0.8Sb₂ and demonstrate the existence of Dirac fermions.

[Characteristics and drug resistance of non-O157 Shiga toxin-producing E. coli in animal feces, from Shandong Province]

Objective: To understand the infection status, characteristics and drug resistance of non-O157 Shiga toxin-producing E. coli (STEC) in animal feces in Shandong Province. Methods: From 2015 to 2016, convient sampling method was used to collect 1 022 fresh feces of animals in Weishan county and Laizhou city, and 24 non-O157 STEC were isolated. The serotypes of non-O157 STEC strains were confirmed through serum agglutination test. The susceptibility was explored through the antimicrobial sensitivity experiments. ESBLs activity was confirmed by double-disc diffusion. PCR method was used to detect the resistance genes. PFGE typing was operated to assess the relatedness and variability of the strains. The multi-locus sequence typing (MLST) was adopted to get the allelic profile and ST sequence of strains. Analysis was made on the evolutionary relationship between different ST groups was made through CLC Sequence Viewer and Counting Express. Results: A total of 24 non-O157 STEC were isolated from animal feces. 23 strains were from pig feces, and 1 strain was from cow feces, and the serotypes were more dispersed. All of the 24 strains carried stx2 genes. The highest resistance rate was sulfamethoxazole(22 strains), the mount of cotrimoxazole and nalidixic acid was 18 strains, chloramphenicol was 13 strains, tetracycline was 19, and there was a phenomenon of multiple drug resistance. The drug resistance spectrum was sulfamethoxazole tetracycline-compound novammin-naphthidine-chloramphenicol. All strains were sensitive to cefepime and imipenem. The ESBLs confirmatory test showed that 4 strains of non O157 STEC produced beta lactamase. PCR detected 7 resistance genes, and 4 tetracycline resistance genes (Tet A, Tet B, tetC and tetD) were detected. The beta lactamase resistance genes (blaSHV-1, bla CTX-M, bla TEM) were all negative. 24 strains were divided into 15 PFGE types, and their clustering results were more dispersed and no dominant PFGE type. There were 11 kinds of MLST types, most of them are ST540 and ST5133 types, each of which was 4 strains, and clustered into 1 MLST genomes. Conclusion: The serotypes of non-O157 STEC in animal feces O157 STEC were dispersed, and the resistant rate to common antibiotic was high. MLST typing results presents obvious polymorphism. Surveillance and manage ment of these strains should be strengthened.

[Abnormal expression of angiopoietin-2 associated with invasion, metastasis and prognosis of lung cancer]

Objective: To investigate the relationship between abnormal angiopoietin-2 (Ang-2) expression and invasion/metastasis of lung cancer. Methods: Totally 122 cases of postoperative primary lung cancer tissues and their paracancerous tissues from Jan. 2009 to Dec. 2010 were collected from Affiliated Hospital of Nantong University and Ang-2 expression was analyzed by immunohistochemistry. At the cellular level, the protein and mRNA levels of Ang-2 in lung epithelial cell line Beas-2B and four lung cancer cell lines (SPCA-1, NCI-1650, A549 and NCI-H1975) were observed. The most effective Ang-2-shRNA for Ang-2 transcription was screened and transfected into A 549 lung cancer cells. The Ang-2 expression, Ang-2 gene transcription, cell proliferation, invasion/metastasis, and epithelial-mesenchymal transition (EMT) abilities of lung cancer cells were analyzed by Western blotting, fluorescent quantitative reverse transcriptase PCR, Cell Counting Kit-8 assay, and Transwell cell models for exploring the relationship between Ang-2 expression and invasion/metastasis of lung cancer. Results: The higher Ang-2 expression levels in lung cancerous tissues were closely related to tumor diameter (P=0.008), differentiating degree (P=0.033), TNM stage (P=0.025) and 5-year survival rate (P<0.001). According to the Kaplan-Meier survival curves, the 5-year survival rate of patients with higher expression levels of Ang-2 (16.1%) was significantly poorer than that of patients with lower Ang-2 (80.0%, P<0.001). Significant difference of 5-year survival rate was found in patients with different Ang-2 levels at TNM stage Ⅰ(P<0.001), but not at stage Ⅱ, Ⅲ and Ⅳ. Among Beas-2B and four lung cancer cell lines, the protein and mRNA levels of Ang-2 in A549 cells were the highest. After Ang-2-shRNA-1 plasmid successfully transfected into A549 cells, cell proliferation rate was significantly lower than that in the shRNA-negative or blank group at a time-dependent manner. The significant decrease of the invasion, migration and EMT abilities were also found in A549 cells after transfection of Ang-2 shRNA. Conclusion: Abnormal expression of Ang-2 is closely related to invasion, migration and prognosis of lung cancer, and interfering the activation of Ang-2 would be a novel molecular-targeted therapy for lung cancer.