Valvular and infection-associated risk factors as criteria to guide the use of echocardiography in patients with native joint infections.

BACKGROUND: Native joint and bone infections (NJBI) are associated with infective endocarditis (IE) in 15% of cases. There are no studies analyzing the use of cardiac imaging in cases of NJBI. The objective of this study was to identify factors associated with echocardiography suggestive of IE in patients with NJBI. METHODS: This medical records review was conducted in patients hospitalized for NJBI between 2007 and 2017 in Rheumatology and Infectious Diseases departments of 2 university hospitals. Patients included had a microbiologically proven NJBI during their hospitalization. RESULTS: In this cohort of 546 patients, median age 66 years, echocardiography was suggestive of IE in 66 (12%). In multivariate analysis, factors associated with echocardiography suggestive of IE were 2 or more positive blood cultures (OR 11.55 (CI95% 3.24-74.20)), cardiac conditions with a high risk of IE (OR 7.34 (CI95% 2.95-18.61)), unknown heart murmur (OR 4.59 (CI95% 1.79-11.74)), multifocal infection (OR 2.26 (CI95% 1.21-4.23)) and an infection due to S. bovis (OR 3.52 (CI95% 1.26-9.79)). The factor associated with the absence of an echocardiography evocative of IE was infection due to unconventional bacteria for IE (OR 0.13 (CI95% 0.01-0.76)). According to the factors associated with echocardiography evocative of IE, we propose the Normandy score based on three kinds of data: cardiac condition, bacterial strain and NJBI mechanism. Echocardiography should be realized when this score, whose negative predictive value is 100% CI95% (98-100%) for prescription of echocardiography, is more than zero. CONCLUSIONS: A score based on valvular condition, bacterial strain and NJBI mechanism could guide clinicians in prescribing echocardiography during NJBI with an excellent negative predictive value.

Dirhamnolipids secreted from Pseudomonas aeruginosa modify anjpegungal susceptibility of Aspergillus fumigatus by inhibiting ß1,3 glucan synthase activity.

Pseudomonas aeruginosa and Aspergillus fumigatus are the two microorganisms responsible for most of the chronic infections in cystic fibrosis patients. P. aeruginosa is known to produce quorum-sensing controlled rhamnolipids during chronic infections. Here we show that the dirhamnolipids secreted from P. aeruginosa (i) induce A. fumigatus to produce an extracellular matrix, rich in galactosaminogalactan, 1,8-dihydroxynaphthalene (DHN)- and pyo-melanin, surrounding their hyphae, which facilitates P. aeruginosa binding and (ii) inhibit A. fumigatus growth by blocking ß1,3 glucan synthase (GS) activity, thus altering the cell wall architecture. A. fumigatus in the presence of diRhls resulted in a growth phenotype similar to that upon its treatment with anjpegungal echinocandins, showing multibranched hyphae and thicker cell wall rich in chitin. The diRhl structure containing two rhamnose moieties attached to fatty acyl chain is essential for the interaction with ß1,3 GS; however, the site of action of diRhls on GS is different from that of echinocandins, and showed synergistic anjpegungal effect with azoles.