Background Our study was to investigate the prevalence of carbapenemase genes in strains of Enterobacteriaceae species exhibiting decreased susceptibility to carbapenems in our hospital. Methods The carbapenemase producing Enterobacteriaceae species were confirmed by modified Hodge test (MHT) and EDTA-disc synergy test which indicating the production of class B carbapenemases. PCR and sequencing analysis were used to identify the drug-resistant genes. DNA fingerprinting based on enterobacterial repetitive intergenic consensus (ERIC)-PCR was applied to investigate the homology of Enterobacteriaceae species. Results From a collection of 1,472 Enterobacteriaceae species, 18 isolates with decreased susceptibility to carbapenem treatment were identified and 9 of which were positive by MHT, and 6 of which produced class B carbapenemases. PCR and sequencing analysis of the 18 isolates revealed 4 different carbapenemase genes ( bla IMP-8 , bla oxa-1 , bla IMP-26 , and bla oxa-47 ) in 10 isolates, with the bla IMP-8 and bla oxa-1 genes being the most common (60-70% prevalence). ERIC-PCR showed 5, 2, and 2 unique genotypes for Enterobacter cloacae , Escherichia coli , and Klebsiella pneumoniae , respectively. Three E. coli strains isolated from different patients from the urologic surgery department exhibited the same DNA banding pattern, suggesting a possible clonal dissemination. Majority (17/18) of the carbapenem-unsusceptible Enterobacteriaceae species isolates was obtained from the surgery department of our hospital. Conclusions The main carbapenemase genes of Enterobacteriaceae species in our hospital were bla IMP-8 and bla oxa-1 . Prevalence of carbapenem resistance may be existed in surgery department and infection control should be taken for preventing further dissemination of drug-resistant strains.

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plays an important role in linezolid resistance and may serve as a marker for resistance screening. Since the L3 and L4 mutations did not simultaneously occur in the same strain, they play a negligible role in linezolid resistance. Epidemiological investigation suggested that the LRE cases were sporadic.

Despite increasing reports of low-level linezolid-resistant enterococci worldwide, the mechanism of this resistance remains poorly understood. Previous transcriptome studies of low-level linezolid-resistant Enterococcus faecalis isolates have demonstrated a number of significantly up-regulated genes potentially involved in mediation of drug resistance. However, whether the transcriptome faithfully reflects the proteome remains unknown. In this study, we performed quantitative proteomics analysis of membrane proteins in an E. faecalis isolate (P10748) with low-level linezolid-resistance in comparison with two linezolid-susceptible strains 3138 and ATCC 29212, all of which have been previously investigated by whole transcriptome analysis. A total of 8,197 peptides associated with 1,170 proteins were identified in all three isolates with false discovery rate (FDR) at 1% and P < 0.05. There were 14 significantly up-regulated and 6 significantly down-regulated proteins in strain P10748 compared to strains 3138 and ATCC 29212, which were in general positively correlated with transcription levels revealed in previous transcriptome studies. Our analysis suggests that the low-level linezolid-resistance in E. faecalis is conferred primarily by the ATP-binding cassette protein OptrA through ribosomal protection and, possibly, also by the enterococcal surface protein (Esp) and other proteins through biofilm formation. The genetic transfer of optrA is potentially regulated by the surface exclusion protein Sea1, conjugal transfer protein TraB, replication protein RepA and XRE family transcription regulator protein. This report represents the first investigation of the mechanisms of linezolid-resistance in E. faecalis by a quantitative proteomics approach.

Purpose: To investigate the potential mechanism and molecular characteristics of linezolidnon-sensitive Enterococcus faecium from a tertiary hospital in southwest China and characterize the relevant plasmids. Patients and Methods: Linezolid-non-sensitive Enterococcus faecium (LNSEFM) isolates collected from January 2014 to December 2018 were screened for resistant genes 23s rRNA, rplC, rplD, rplV, optrA, cfr, poxtA, by PCR. Molecular epidemiological analysis was performed by multilocus sequence typing (MLST). The optrA-and-poxtA co-harboring strain EFM_7150 was subjected to the whole genome sequencing (WGS) by Illumina HiSeq and Oxford Nanopore MinION. Results: A total of 15 LNSEFM with linezolid MICs ranging from 4 to 16 mg/L were identified. About 66.7% (10/15) of isolates were linezolid-resistant. About 46.7% (7/15) of strains were positive for optrA. Two types of optrA variants (P and EYDNDM) were identified. About 13.3% (2/15) of isolates had poxtA. 1 harbored a L22 protein alteration (Ser77Thr). One isolate coharbored optrA (EYDNDM variant) and poxtA. There was no mutation in the gene that encoded the ribosomal protein L3/L4 or the domain V of 23S rRNA. No cfr gene was detected. Based on WGS data, optrA was associated with Tn558 inserted to radC gene and poxtA was flanked by IS1216E. Conclusion:OptrA is primary mechanism in linezolid-resistant Enterococcus faecium. This is the first report ofoptrA variants P and EYDNDM identified in Enterococcus faecium and optrA-and-poxtA co-harboring Enterococcus faecium clinically in southwest China. Besides, Tn558 and IS1216Es may play an important role in the dissemination of optrA and poxtA, respectively. The findings revealed the potential threat to nosocomial infection by optrA and coexistence of optrA and poxtA in Enterococcus faecium. Thus, clinical surveillance of linezolid-resistant Enterococcus is urgently needed.

The increased reporting of carbapenem-resistant hypervirulent K. pneumoniae is considered a worrisome concern to human health care and has restricted the choice of effective antibiotics for clinical treatment. Moreover, virulence plasmids with complete conjugation modules have been identified, which evolved via homologous recombination.

Spermatogenesis is a complicated course of several rigorous restrained steps that spermatogonial stem cells undergo to develop into highly specialized spermatozoa; however, specific genes and signal pathways, which regulate the amplification, differentiation and maturation of these cells, remain unclear. We performed bioinformatics analyses to investigate the dynamic changes of the gene expression patterns at three time points in the course of the first wave of rat spermatogenesis. Differently expressed genes (DEGs) were identified, and the features of DEGs were further analyzed with GO (Gene Ontology), KEGG (Kyoto Encyclopedia of Genes and Genomes) and Short Time-series Expression Miner (STEM). A total of 2954 differentially expressed genes were identified. By using STEM, the top 10 key genes were selected in the profile according to the enrichment results, and the distinguishable biological functions encoded by these DEGs were automatically divided into three parts. Genes from 6, 8 and 10 days were related to biosynthesis, immune response and cell junction, and genes from 14, 15 and 16 days were related to energy metabolic pathways. The results also suggest that genes from 29, 31 and 35 days may shift metabolic to sperm motility, sperm flagellum and cilium movement.

Background Hypervirulent klebsiella pneumoniae (hvKP) is responsible for various invasive diseases and is associated with high mortality. However, the clinical and microbiological factors of hvKP infection to affect prognosis are not well studied. The purpose of this study is to evaluate prognostic factors of in-hospital mortality of hvKP infection, mainly focusing on clinical and microbiological characteristics. Methods A retrospective study was conducted in southwestern China from February 2018 to June 2019 and strains positive for aerobactin and string test were defined as hvKP. According to the clinical outcomes during hospitalization, hvKP infected patients were divided into non-survivor group and survivor group. The clinical characteristics, capsule serotypes, multi-locus sequence types, virulence genes and antimicrobial susceptibility were compared between the two groups. Results A total of 135 patients were classified as hvKP infection, with a prevalence rate of 22% and an in-hospital mortality rate of 11.9%. Univariate analysis exhibited that admission to intensive care unit (ICU)(p=0.008) and antimicrobial resistance of hvKP such as ampicillin/sulbactam(p=0.028), cefepime(p=0.033), aztreonam(p=0.049) and harboring iroN gene(p=0.023) were associated with higher in-hospital mortality. On the contrary, the rmpA gene showed an inverse association with in-hospital mortality(p=0.017). Multivariate logistic regression analysis revealed that admission to ICU (odds ratio [OR]=3.452, 95% confidence interval [CI]=1.052-11.329; P=0.041) and presence of iroN (OR=9.278, 95% CI=1.654-52.035; P=0.011) was considered to be the independent prognostic factors for in-hospital mortality of hvKP infection. Conclusion Emerging hvKP infection may lead to relatively high in-hospital mortality. Therefore, early surveillance and better management are necessary for patients admitted to ICU and infected with hvKP harboring iroN gene.