Browsing by Author "Di Bonaventura, Giovanni (7003845013)"

The ability to form biofilms is a recognized trait of Stenotrophomonas maltophilia, but the extent of its clinical relevance is still unclear. The present multicenter prospective study (ANSELM) aims at investigating the association between biofilm formation and clinical outcomes of S. maltophilia infections. One hundred and nine isolates were collected from various geographical origins and stratified according to their clinical relevance. Biofilm formation was evaluated by the microtiter plate assay and correlated with microbiological and clinical data from the associated strains. Antibiotic susceptibility of the planktonic cells was tested by the disk diffusion technique, while antibiotic activity against mature biofilms was spectrophotometrically assessed. Most strains (91.7%) were able to form biofilm, although bloodborne strains produced biofilm amounts significantly higher than strains causing hospital-rather than community-acquired infections, and those recognized as “definite” pathogens. Biofilm formation efficiency was positively correlated with mechanical ventilation (p = 0.032), whereas a negative relationship was found with antibiotic resistance (r2 = 0.107; p < 0.001), specifically in the case of the pathogenic strains. Mature S. maltophilia biofilms were markedly more resistant (up to 128 times) to cotrimoxazole and levofloxacin compared with their planktonic counterparts, especially in the case of bloodborne strains. Our findings indicate that biofilm formation by S. maltophilia is obviously a contributing factor in the pathogenesis of infections, especially in deep ones, thus warranting additional studies with larger cohort of patients and isolates. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.

The ability to form biofilms is a recognized trait of Stenotrophomonas maltophilia, but the extent of its clinical relevance is still unclear. The present multicenter prospective study (ANSELM) aims at investigating the association between biofilm formation and clinical outcomes of S. maltophilia infections. One hundred and nine isolates were collected from various geographical origins and stratified according to their clinical relevance. Biofilm formation was evaluated by the microtiter plate assay and correlated with microbiological and clinical data from the associated strains. Antibiotic susceptibility of the planktonic cells was tested by the disk diffusion technique, while antibiotic activity against mature biofilms was spectrophotometrically assessed. Most strains (91.7%) were able to form biofilm, although bloodborne strains produced biofilm amounts significantly higher than strains causing hospital-rather than community-acquired infections, and those recognized as “definite” pathogens. Biofilm formation efficiency was positively correlated with mechanical ventilation (p = 0.032), whereas a negative relationship was found with antibiotic resistance (r2 = 0.107; p < 0.001), specifically in the case of the pathogenic strains. Mature S. maltophilia biofilms were markedly more resistant (up to 128 times) to cotrimoxazole and levofloxacin compared with their planktonic counterparts, especially in the case of bloodborne strains. Our findings indicate that biofilm formation by S. maltophilia is obviously a contributing factor in the pathogenesis of infections, especially in deep ones, thus warranting additional studies with larger cohort of patients and isolates. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.

The details of all steps involved in the quantification of biofilm formation in microtiter plates are described. The presented protocol incorporates information on assessment of biofilm production by staphylococci, gained both by direct experience as well as by analysis of methods for assaying biofilm production. The obtained results should simplify quantification of biofilm formation in microtiter plates, and make it more reliable and comparable among different laboratories. Copyright © Apmis 2007.