Molecular characterization of MRSA collected during national surveillance between 2008 and 2019 in the Netherlands

Background.Although the Netherlands is a country with a low endemic level, methicillin-resistant Staphylococcus aureus (MRSA) poses a significant health care problem. Therefore, high coverage national MRSA surveillance has been in place since 1989. To monitor possible changes in the type-distribution and emergence of resistance and virulence, MRSA isolates are molecularly characterized.Methods.All 43,321 isolates from 36,520 persons, collected 2008-2019, were typed by multiple-locus variable number tandem repeats analysis (MLVA) with simultaneous PCR detection of the mecA, mecC and lukF-PV genes, indicative for PVL. Next-generation sequencing data of 4991 isolates from 4798 persons were used for whole genome multi-locus sequence typing (wgMLST) and identification of resistance and virulence genes.Results.We show temporal change in the molecular characteristics of the MRSA population with the proportion of PVL-positive isolates increasing from 15% in 2008-2010 to 25% in 2017-2019. In livestock-associated MRSA obtained from humans, PVL-positivity increases to 6% in 2017-2019 with isolates predominantly from regions with few pig farms. wgMLST reveals the presence of 35 genogroups with distinct resistance, virulence gene profiles and specimen origin. Typing shows prolonged persistent MRSA carriage with a mean carriage period of 407 days. There is a clear spatial and a weak temporal relationship between isolates that clustered in wgMLST, indicative for regional spread of MRSA strains.Conclusions.Using molecular characterization, this exceptionally large study shows genomic changes in the MRSA population at the national level. It reveals waxing and waning of types and genogroups and an increasing proportion of PVL-positive MRSA.A group of bacteria that cause difficult-to-treat infections in humans is methicillin-resistant Staphylococcus aureus (MRSA). The aim of this study was to monitor changes in the spread of MRSA, their disease causing potential and resistance to antibiotics used to treat MRSA infections. MRSA from patients and their contacts in the Netherlands were collected over a period of 12 years and characterized. This revealed new types of MRSA emerged and others disappeared. An increasing number of MRSA produces a protein called PVL toxin, enabling MRSA to cause more severe infections. Also, some people appear to carry MRSA without any disease for more than a year. These findings suggest an increasing disease potential of MRSA and possible unnoticed sources of infection. Consequently, it is important to maintain monitoring of these infections to minimize MRSA spread.Schouls et al. characterize 43,321 methicillin-resistant Staphylococcus aureus (MRSA) isolates obtained between 2008 and 2019 in the Netherlands. Genomic changes occur in the MRSA population, with increases in the proportion of PVL-positive MRSA.Molecular basis of bacterial pathogenesis, virulence factors and antibiotic resistanc

A Calculation Study on Neutron Kinetics and Thermodynamics of a Gaseous Core Fission Reactor

Applied Science

Effect of sugar-sweetened beverages on body weight in children: design and baseline characteristics of the Double-blind, Randomized INtervention study in Kids.

Background: Intake of sugar-sweetened beverages is associated with overweight in observational studies. A possible explanation is that liquid sugars do not satiate and that their intake is not compensated by reduced caloric intake from other foods. However, evidence from intervention studies for this hypothesis is inconclusive because previous studies were not blinded. Hence results may have been influenced by expectations and behavioral cues rather than by physiological mechanisms. Methods: We designed the Double-blind, Randomized INtervention study in Kids (DRINK) to examine the effect on body weight of covertly replacing sugar-sweetened by sugar-free beverages. Children were only eligible if they habitually drank sugar-sweetened beverages. We recruited 642 healthy children (mean age 8.2, range 4.8-11.9). We designed, tested and produced custom-made beverages containing 10% sugar and sugar-free beverages with the same sweet taste and look. Children receive one 250. mL can of study beverage daily for 18. months. We perform body measurements at 0, 6, 12 and 18. months. The primary outcome is the z-score of BMI for age. The maximum predicted difference in this score between groups is 0.72, which corresponds with a difference in body weight of 2.3. kg. Discussion: The double-blind design eliminates behavioral factors that affect body weight. If children gain less body fat when drinking sugar-free than when drinking sugar-sweetened beverages that would show that liquid sugar indeed bypasses biological satiation mechanisms. It would also suggest that a reduction in liquid sugars could decrease body fat more effectively than reduction of other calorie sources. © 2011 Elsevier Inc