Low-Threshold Testing for SARS-CoV-2 (COVID-19) in Long-Term Care Facilities Early in the First Pandemic Wave, the Twente Region, the Netherlands: A Possible Factor in Reducing Morbidity and Mortality.

During the first wave of the COVID-19 pandemic, there was a shortage of SARS-CoV-2 diagnostic tests, and testing patients with mild symptoms (low-threshold testing) was not recommended in the Netherlands. Despite these guidelines, to protect those who were most at risk, low-threshold testing was advocated and offered to the majority of long-term care institutions in the region. In this manner, 144 healthcare workers and 96 residents tested SARS-CoV-2-positive and were isolated before the same service was provided nationwide by public health services.

Increased D-alanylation of lipoteichoic acid and a thickened septum are main determinants in the nisin resistance mechanism of Lactococcus lactis.

Nisin is a post-translationally modified antimicrobial peptide produced by Lactococcus lactis which binds to lipid II in the membrane to form pores and inhibit cell-wall synthesis. A nisin-resistant (Nis(R)) strain of L. lactis, which is able to grow at a 75-fold higher nisin concentration than its parent strain, was investigated with respect to changes in the cell wall.

Elucidation of the antimicrobial mechanism of mutacin 1140.

Mutacin 1140 and nisin A are peptide antibiotics that belong to the lantibiotic family. N-Terminal rings A and B of nisin A and mutacin 1140 (lipid II-binding domain) share many structural and sequence similarities. Nisin A binds lipid II and thus disrupts cell wall synthesis and also forms transmembrane pores.

An alternative bactericidal mechanism of action for lantibiotic peptides that target lipid II.

Lantibiotics are polycyclic peptides containing unusual amino acids, which have binding specificity for bacterial cells, targeting the bacterial cell wall component lipid II to form pores and thereby lyse the cells. Yet several members of these lipid II-targeted lantibiotics are too short to be able to span the lipid bilayer and cannot form pores, but somehow they maintain their antibacterial efficacy. We describe an alternative mechanism by which members of the lantibiotic family kill Gram-positive bacteria by removing lipid II from the cell division site (or septum) and thus block cell wall synthesis.

Size and orientation of the lipid II headgroup as revealed by AFM imaging.

In this study, we investigated the size and orientation of the bacterial Lipid II (L II) headgroup when the L II molecule is present in liquid-crystalline domains of DOPC in a supported DPPC bilayer. Using atomic force microscopy, we detected that L II causes the appearance of a 1.9 nm thick layer, situated over the DOPC headgroup region.