[COVID-19: patient zero in the Netherlands]. / COVID-19: patiënt nul in Nederland.

BACKGROUND: Since December 2019, the world is captivated by SARS-CoV-2, a new coronavirus that shows a lot of similaritieswith previous coronaviruses such as SARS and MERS. Although it was initially seen mainly in China and the surrounding countries, now it also reached Europe, where a large region in northern Italy, in particular, encountered many infections. CASE DESCRIPTION: Here we describe the first Dutch patient with COVID-19, a 56-year-old man whose infection appeared to be related to a trip to Northern Italy one week before presentation. In the days that followed, the brother of the patient with whom he had traveled, his wife and daughter also tested positive. CONCLUSION: At the moment much is still unclear and it is particularly important to quickly identify patients with an increased risk of complications and to prevent unrestrained spread in the Netherlands.

Enrichment broth improved detection of extended-spectrum-beta-lactamase-producing bacteria in throat and rectal surveillance cultures of samples from patients in intensive care units.

We evaluated the use of a trypticase soy broth (TSB) for improving detection of extended-spectrum-beta-lactamase-producing (ESBL(+)) bacteria. Preenrichment of throat and rectal swabs in TSB prior to inoculation on solid medium doubled the number of ESBL(+) bacteria detected in samples obtained from patients in our intensive care unit.

3-D Structure of multilaminar lysosomes in antigen presenting cells reveals trapping of MHC II on the internal membranes.

In late endosomes and lysosomes of antigen presenting cells major histocompatibility complex class II (MHC II) molecules bind peptides from degraded internalized pathogens. These compartments are called MHC class II compartments (MIICs), and from here peptide-loaded MHC II is transported to the cell surface for presentation to helper T-lymphocytes to generate an immune response. Recent studies from our group in mouse dendritic cells indicate that the MHC class II on internal vesicles of multivesicular late endosomes or multivesicular bodies is the main source of MHC II at the plasma membrane. We showed that dendritic cell activation triggers a back fusion mechanism whereby MHC II from the inner membranes is delivered to the multivesicular bodies' outer membrane. Another type of MIIC in B-lymphocytes and dendritic cells is more related to lysosomes and often appears as a multilaminar organelle with abundant MHC II-enriched internal membrane sheets. These multilaminar lysosomes have a functioning peptide-loading machinery, but to date it is not clear whether peptide-loaded MHC II molecules from the internal membranes can make their way to the cell surface and contribute to T cell activation. To obtain detailed information on the membrane organization of multilaminar lysosomes and investigate possible escape routes from the lumen of this organelle, we performed electron tomography on cryo-immobilized B-lymphocytes and dendritic cells. Our high-resolution 3-D reconstructions of multilaminar lysosomes indicate that their membranes are organized in such a way that MHC class II may be trapped on the inner membranes, without the possibility to escape to the cell surface.