Extensive antimicrobial resistance and plasmid-carrying resistance genes in mcr-1-positive E. coli sampled in swine, in Guangxi, South China.

BACKGROUND: The discovery of the superbug mcr-1-positive Escherichia coli (MCRPEC) has drew greet attention. Swine-origin multi-drug resistant MCRPEC has been a potential threat to public health and safety. However, there were few detailed studies have been reported on swine MCRPEC in Guangxi, South China. RESULTS: In this study, thirty-three MCRPEC strains were detected from 142 E. coli strains from 116 samples in Guangxi in 2018. Which could be classified into eight unique STs and a total of six incompatibility plasmid groups (IncFI, IncHI1, IncY, IncN, IncI1 and IncX1). After that, the susceptibility of MCRPEC isolates to 27 antimicrobial agents belonging to 17 antimicrobial categories was tested. There were nineteen E. coli resistant to 3rd and 4th generation cephalosporins and twelve E. coli resistant to carbapenem resistan. Importantly, the MCRPEC showed high resistance highly resistance for imipenem and meropenem, which were forbidden to use in livestock production. Three MCRPEC strains were further proved to be extensively drug-resistant (XDR), and the other isolates were multi-drug-resistant (MDR). Furthermore, we found that the plasmid-carrying resistance genes coexisted with the mcr-1 gene of the MCRPEC isolates. Which were listed as follows: ß-lactamase antimicrobial resistance genes e.g. ESBL genes (blaCTX-M14, blaCTX-M24, blaCTX-M123, blaOXA-1), plasmid-mediated AmpC (pAmpC) gene (blaCMY-2), the carbapenem resistance gene (blaNDM-5), and non-ß-lactamase antimicrobial resistance genes (qnrA, qnrB, qnrS, aac (6')-Ib-cr, tetA, tetB, sul1, sul2, floR, aadA). CONCLUSION: Thirty-three mcr-1-positive E. coli isolates in Guangxi displayed a wide profile of antimicrobial resistance. Plasmid-carrying resistance genes might be the main cause of MCRPEC multidrug resistance. This study highlighted the necessity for long-term surveillance of mcr-1-positive E. coli in pigs.

Transwell isolation and difference analysis of capacitated boar sperm proteins based on the iTRAQ technique.

During capacitation, proteins in boar sperm are released to maintain the stability of their own state and membrane structure. No studies have analyzed the differences between retained proteins and released proteins during sperm capacitation. In the present study, a Transwell chamber and polycarbonate membrane were used to separate the proteins of boar sperm and their released proteins. Isotopically labeled relative and absolute quantification (iTRAQ) was used to analyze each compartment protein. A total of 108 differential proteins were identified in the upper and lower chambers of the Transwell, among which 27 were significantly upregulated (p-value≤0.05 and |log2 (fold change)|≥1) and 81 were significantly downregulated (p-value≤0.05 and |log2 (fold change)|≤1). These differential proteins were mainly involved in biological processes (e.g., the regulation of cysteine peptidase activity, transmembrane transportation, ion transportation and ATP synthesis) and major signaling pathways (e.g., glutathione/galactose metabolism, cellular adhesion and PI3K-Akt), and most of them interacted with each other to some extent. In conclusion, retained proteins and released proteins of capacitated sperm were effectively separated using a Transwell chamber, and differential proteins were successfully identified from among the proteins. Bioinformatics analysis suggested that these differential proteins affect sperm capacitation mainly by adjusting sperm energy metabolism, motion characteristics and acrosome membrane status.

Identification and complete genome of lytic "Kp34likevirus" phage vB_KpnP_Bp5 and therapeutic potency in the treatment of lethal Klebsiella pneumoniae infections in mice.

Klebsiella pneumoniae (K. pneumoniae) infection exist widely in the farming and medical. The treatment of K. pneumoniae infection is primarily based on antibiotics, which not only leads to a large economic burden but also the development of antibiotic resistance. Bacteriophages therapy present a promising alternative. The object of this study was identifying comprehensively a lytic lethal K. pneumoniae phage vB_KpnP_Bp5, and evaluating the phage as an anti-infective agent in an experimental K. pneumoniae infection murine model. The phage Bp5 had the following characteristics: the optimal number of infections was 0.001, the latent period was 5 min, the outbreak period was 40 min, the burst size was 24 plaque-forming unit (PFU)/cell, the phage could withstand 50 °C temperature and the optimal pH value was 4.0-10.0. According to electron microscopy and whole-genome sequence analysis, the phage should be classified as a member of order Caudovirales, family Podoviridae, subfamily Autographiviridae. Meantime, phylogenetic analysis showed high conservation of gene arrangement and gene content. We demonstrated that administration of phage Bp5 significantly reduced colony formation by K. pneumoniae and alleviated damage to lung tissue. In addition, different therapy time point was closely related to body health and the degree of tissue damage. Once treated promptly, it will greatly reduce mortality and alveolar inflammatory exudation and injury.