Abiotrophia spp. and Granulicatella spp. Infective Endocarditis: A Contemporary Perspective.

BACKGROUND: Abiotrophia spp. and Granulicatella spp. are Gram-positive cocci, formerly known as nutritionally variant or deficient Streptococcus. Their role as causative agents of infective endocarditis (IE) is numerically uncertain, as well as diagnostic and clinical management of this infection. The aim of our study is to describe the clinical, microbiological, therapeutic, and prognosis of patients with IE caused by these microorganisms in a large microbiology department. METHODS: Retrospective analysis of all the patients with Abiotrophia spp. and Granulicatella spp. IE registered in our centre in the period 2004-2021. RESULTS: Of the 822 IE in the study period, 10 (1.2%) were caused by Abiotrophia spp. (7) or Granulicatella spp. (3). The species involved were A.defectiva (7), G.adiacens (2) and G.elegans (1). Eight patients were male, their mean age was 46 years and four were younger than 21 years. The most frequent comorbidities were congenital heart disease (4; 40%) and the presence of intracardiac prosthetic material (5; 50%). IE occurred on 5 native valves and 5 prosthetic valve or material. Blood cultures were positive in 8/10 patients, within a mean incubation period of 18.07 hours. In the other two patients, a positive 16SPCR from valve or prosthetic material provided the diagnosis. Surgery for IE was performed in seven patients (70%) and in all cases positive 16S rRNA PCR and sequencing from valve or prosthetic material was demonstrated. Valves and/or prosthetic removed material cultures were positive in four patients. Nine patients received ceftriaxone (4 in monotherapy and 5 in combination with other antibiotics). The mean length of treatment was 6 weeks and IE-associated mortality was 20% at one year follow-up. CONCLUSIONS: Abiotrophia spp. or Granulicatella spp. IE were infrequent but not exceptional in our environment and particularly affected patients with congenital heart disease or prosthetic material. Blood cultures and molecular methods allowed the diagnosis. Most of them required surgery and the associated mortality, in spite of a mean age of 46 years, was high.

Pool of resistance mechanisms to glyphosate in Digitaria insularis.

Digitaria insularis biotypes resistant to glyphosate have been detected in Brazil. Studies were carried out in controlled conditions to determine the role of absorption, translocation, metabolism, and gene mutation as mechanisms of glyphosate resistance in D. insularis. The susceptible biotype absorbed at least 12% more (14)C-glyphosate up to 48 h after treatment (HAT) than resistant biotypes. High differential (14)C-glyphosate translocation was observed at 12 HAT, so that >70% of the absorbed herbicide remained in the treated leaf in resistant biotypes, whereas 42% remained in the susceptible biotype at 96 HAT. Glyphosate was degraded to aminomethylphosphonic acid (AMPA), glyoxylate, and sarcosine by >90% in resistant biotypes, whereas a small amount of herbicide (up to 11%) was degraded by the susceptible biotype up to 168 HAT. Two amino acid changes were found at positions 182 and 310 in EPSPS, consisting of a proline to threonine and a tyrosine to cysteine substitution, respectively, in resistant biotypes. Therefore, absorption, translocation, metabolism, and gene mutation play an important role in the D. insularis glyphosate resistance.