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... Show moreBackground.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. Show less
Whether temporary antiretroviral treatment during primary HIV infection (PHI) lowers the viral set point or affects the subsequent CD4 count decline remains unclear. The objectives of this study... Show moreWhether temporary antiretroviral treatment during primary HIV infection (PHI) lowers the viral set point or affects the subsequent CD4 count decline remains unclear. The objectives of this study were to analyze the clinical, viral, and immunological effects of temporary early HAART during PHI. This is a cohort study of patients with laboratory evidence of PHI. Independent predictors of early HAART and the viral set point were analyzed using multiple regression analysis. Plasma HIV-1 RNA (pVL) and CD4 trajectories were analyzed using linear mixed models. A total of 332 patients were included in the analysis. Sixty-four patients started HAART within 180 days of seroconversion. A higher baseline pVL was independently predictive of the start of early HAART (OR: 2.69/log10pVL, p = 0.001). Thirty-two patients who interrupted early HAART were compared with 250 patients who remained untreated for more than 180 days after seroconversion. Temporary early HAART was not significantly associated with a longer AIDS-free survival but did result in an initial, but transient lowering of the viral set point. The viral set point was initially 0.6 log copies/ml lower after interruption of early HAART (p<0.001) and remained lower during 83 weeks of follow-up. No significant difference in the slopes of CD4 decline was detected between the groups. Temporary HAART in PHI is started more frequently in patients with a higher pVL and can transiently lower the viral set point compared to never treated patients. Show less