CHROMAgar™ LIN-R as an efficient screening tool to assess the prevalence of linezolid-resistant enterococci in German hospital patients-a multicentre study approach, 2021-2022.

BACKGROUND: In recent years, an increasing number of linezolid-resistant enterococci (LRE) was recognized at the German National Reference Centre (NRC) for Enterococci. National guidelines on infection prevention recommend screening for LRE in epidemiologically linked hospital settings without referring to a reliable and rapid diagnostic method. Since 2020, CHROMAgar™ provide a chromogenic linezolid screening agar, LIN-R, suitable to simultaneously screen for linezolid-resistant staphylococci and enterococci. OBJECTIVES: To assess the applicability of CHROMAgar™ LIN-R in clinical settings for detecting LRE directly from patient material and to infer prevalence rates of LRE amongst German hospital patients. METHODS: During the 3-month trial period, clinical samples were plated on CHROMAgar™ LIN-R. Antimicrobial susceptibility testing was performed using VITEK2 or disc diffusion. At the NRC, linezolid resistance was determined by broth microdilution, multiplex-PCR for cfr/optrA/poxtA and by a restriction-based assay for 23S rDNA mutations. RESULTS: The 12 participating study sites used 13 963 CHROMAgar™ LIN-R plates during the study period. Of 442 presumptive LRE, 192 were confirmed by phenotypic methods. Of these, 161 were received by the NRC and 121 (75%) were verified as LRE. Most of LR-E. faecium 53/81 (65%) exhibited a 23S rRNA gene mutation as the sole resistance-mediating mechanism, whereas optrA constituted the dominant resistance trait in LR-E. faecalis [39/40 (98%)]. Prevalence of LRE across sites was estimated as 1% (ranging 0.18%-3.7% between sites). CONCLUSIONS: CHROMAgar™ LIN-R represents a simple and efficient LRE screening tool in hospital settings. A high proportion of false-positive results demands validation of linezolid resistance by a reference method.

SPOC1 (PHF13) is required for spermatogonial stem cell differentiation and sustained spermatogenesis.

SPOC1 (PHF13) is a recently identified protein that has been shown to dynamically associate with somatic chromatin, to modulate chromatin compaction and to be important for proper cell division. Here, we report on the expression of SPOC1 in promyelocytic leukaemia zinc finger (PLZF)-positive undifferentiated spermatogonial stem cells (SSCs) of the mouse testis. To investigate further the biological function of SPOC1 in germ cells we generated Spoc1 mutant mice from a gene-trap embryonic stem cell clone. Postpubertal homozygous Spoc1(-/-) animals displayed a pronounced progressive loss of germ cells from an initially normal germ epithelium of the testis tubules leading to testis hypoplasia. This loss first affected non-SSC stages of germ cells and then, at a later time point, the undifferentiated spermatogonia. Remarkably, successive loss of all germ cells (at >20 weeks of age) was preceded by a transient increase in the number of undifferentiated A(aligned) (A(al)) spermatogonia in younger mice (at >10 weeks of age). The number of primary Spoc1(-/-) gonocytes, the proliferation of germ cells, and the initiation and progression of meiosis was normal, but we noted a significantly elevated level of apoptosis in the Spoc1(-/-) testis. Taken together, the data argue that SPOC1 is indispensable for stem cell differentiation in the testis and for sustained spermatogenesis.

C4ORF48, a gene from the Wolf-Hirschhorn syndrome critical region, encodes a putative neuropeptide and is expressed during neocortex and cerebellar development.

In order to identify novel genes involved in mental retardation/intellectual disability, we focused on a microdeletion reported in a patient with a mild form of Wolf-Hirschhorn syndrome. This patient presented with attention-deficit hyperactivity disorder, some learning and fine motor deficits as well as facial abnormalities. The deleted region included three genes. Here, we report the first characterization of one of these genes, C4ORF48. C4ORF48 encodes a short (139 aa) evolutionarily conserved protein with a predicted signal peptide and two potential dibasic convertase cleavage sites. In mice, we demonstrated expression of the corresponding protein exclusively in brain tissue using an anti-mouse C4Orf48 polyclonal antibody. Detailed RNA in situ hybridization experiments revealed expression of C4Orf48 in different zones during cortical and cerebellar development, as well as in almost all cortical and subcortical regions of the adult mouse brain. Based on the present data, we propose that C4Orf48 probably encodes a novel neuropeptide, which, if hemizygously deleted, may be involved in the observed intellectual and fine motor disabilities and thus in the overall neurological aspects of Wolf-Hirschhorn syndrome.

Frequent inactivation of cysteine dioxygenase type 1 contributes to survival of breast cancer cells and resistance to anthracyclines.

PURPOSE: Genome-wide DNA methylation analyses have identified hundreds of candidate DNA-hypermethylated genes in cancer. Comprehensive functional analyses provide an understanding of the biologic significance of this vast amount of DNA methylation data that may allow the determination of key epigenetic events associated with tumorigenesis. EXPERIMENTAL DESIGN: To study mechanisms of cysteine dioxygenase type 1 (CDO1) inactivation and its functional significance in breast cancer in a comprehensive manner, we screened for DNA methylation and gene mutations in primary breast cancers and analyzed growth, survival, and reactive oxygen species (ROS) production in breast cancer cells with restored CDO1 function in the context of anthracycline treatment. RESULTS: DNA methylation-associated silencing of CDO1 in breast cancer is frequent (60%), cancer specific, and correlates with disease progression and outcome. CDO1 function can alternatively be silenced by repressive chromatin, and we describe protein-damaging missense mutations in 7% of tumors without DNA methylation. Restoration of CDO1 function in breast cancer cells increases levels of ROS and leads to reduced viability and growth, as well as sensitization to anthracycline treatment. Priming with 5-azacytidine of breast cancer cells with epigenetically silenced CDO1 resulted in restored expression and increased sensitivity to anthracyclines. CONCLUSION: We report that silencing of CDO1 is a critical epigenetic event that contributes to the survival of oxidative-stressed breast cancer cells through increased detoxification of ROS and thus leads to the resistance to ROS-generating chemotherapeutics including anthracyclines. Our study shows the importance of CDO1 inactivation in breast cancer and its clinical potential as a biomarker and therapeutic target to overcome resistance to anthracyclines.