scholarly journals Impact of sarA on Antibiotic Susceptibility of Staphylococcus aureus in a Catheter-Associated In Vitro Model of Biofilm Formation

2009 ◽  
Vol 53 (6) ◽  
pp. 2475-2482 ◽  
Author(s):  
Elizabeth C. Weiss ◽  
Horace J. Spencer ◽  
Sonja J. Daily ◽  
Brian D. Weiss ◽  
Mark S. Smeltzer
Keyword(s):  
Staphylococcus Aureus ◽  
Clinical Isolate ◽  
Antimicrobial Susceptibility ◽  
Antibiotic Susceptibility ◽  
Biofilm Formation ◽  
In Vitro Model ◽  
Susceptibility Testing ◽  
Specific Context ◽  
Vitro Model

ABSTRACT Mutation of the staphylococcal accessory regulator (sarA) in Staphylococcus aureus limits but does not abolish the capacity of the organism to form a biofilm. As a first step toward determining whether this limitation is therapeutically relevant, we carried out in vitro studies comparing the relative susceptibility of an S. aureus clinical isolate (UAMS-1) and its isogenic sarA mutant (UAMS-929) in the specific context of a catheter-associated biofilm. The antibiotics tested were daptomycin, linezolid, and vancomycin, all of which were evaluated by using concentrations based on the MIC defined as the breakpoint for a susceptible strain of S. aureus (≤1.0, ≤2.0, and ≤4.0 μg/ml for daptomycin, vancomycin, and linezolid, respectively). Mutation of sarA had no significant impact on the MIC of UAMS-1 for any of the targeted antibiotics, as defined by Etest antimicrobial susceptibility testing. However, mutation of sarA did result in a significant increase in antimicrobial susceptibility to all targeted antibiotics when they were tested in the specific context of a biofilm. Additionally, whether susceptibility was assessed by using UAMS-1 or its sarA mutant, daptomycin was found to be more effective against established S. aureus biofilms than either linezolid or vancomycin.

scholarly journals Highly variable effect of sonication to dislodge biofilm-embedded Staphylococcus epidermidis directly quantified by epifluorescence microscopy: an in vitro model study

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Erik T. Sandbakken ◽  
Eivind Witsø ◽  
Bjørnar Sporsheim ◽  
Kjartan W. Egeberg ◽  
Olav A. Foss ◽  
...  
Keyword(s):  
Staphylococcus Epidermidis ◽  
Biofilm Formation ◽  
In Vitro Model ◽  
Laser Scanning Microscopy ◽  
Epifluorescence Microscopy ◽  
Variable Effect ◽  
Prosthetic Joint Infections ◽  
Before And After ◽  
Vitro Model

Abstract Background In cases of prosthetic joint infections, culture of sonication fluid can supplement culture of harvested tissue samples for correct microbial diagnosis. However, discrepant results regarding the increased sensitivity of sonication have been reported in several studies. To what degree bacteria embedded in biofilm are dislodged during the sonication process has to our knowledge not been fully elucidated. In the present in vitro study, we have evaluated the effect of sonication as a method to dislodge biofilm by quantitative microscopy. Methods We used a standard biofilm method to cover small steel plates with biofilm forming Staphylococcus epidermidis ATCC 35984 and carried out the sonication procedure according to clinical practice. By comparing area covered with biofilm before and after sonication with epifluorescence microscopy, the effect of sonication on biofilm removal was quantified. Two series of experiments were made, one with 24-h biofilm formation and another with 72-h biofilm formation. Confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) were used to confirm whether bacteria were present after sonication. In addition, quantitative bacteriology of sonication fluid was performed. Results Epifluorescence microscopy enabled visualization of biofilm before and after sonication. CLSM and SEM confirmed coccoid cells on the surface after sonication. Biofilm was dislodged in a highly variable manner. Conclusion There is an unexpected high variation seen in the ability of sonication to dislodge biofilm-embedded S. epidermidis in this in vitro model.

scholarly journals Beneficial Influence of Platelets on Antibiotic Efficacy in an In Vitro Model of Staphylococcus aureus-Induced Endocarditis

2004 ◽  
Vol 48 (7) ◽  
pp. 2551-2557 ◽  
Author(s):  
Renee-Claude Mercier ◽  
Robert M. Dietz ◽  
Jory L. Mazzola ◽  
Arnold S. Bayer ◽  
Michael R. Yeaman
Keyword(s):  
Staphylococcus Aureus ◽  
In Vitro Model ◽  
Antimicrobial Effect ◽  
Human Platelets ◽  
Inhibitory Effects ◽  
Activated Platelets ◽  
Vitro Model ◽  
Antibiotic Efficacy ◽  
Chamber Fluid

ABSTRACT Platelets contribute to antimicrobial host defense against infective endocarditis (IE) by releasing platelet microbicidal proteins (PMPs). We investigated the influence of thrombin-stimulated human platelets on the evolution of simulated IE in the presence and absence of vancomycin or nafcillin. Staphylococcus aureus strains differing in intrinsic susceptibility to PMPs or antibiotics were studied: ISP479C (thrombin-induced PMP-1 [tPMP-1] susceptible; nafcillin and vancomycin susceptible), ISP479R (tPMP-1 resistant; nafcillin and vancomycin susceptible), and GISA-NJ (tPMP-1 intermediate-susceptible; vancomycin intermediate-susceptible). Platelets were introduced and thrombin activated within the in vitro IE model 30 min prior to inoculation with S. aureus. At 0 to 24 h postinoculation, bacterial densities in chamber fluid and simulated endocardial vegetations (SEVs) were quantified and compared among groups. Activated platelets alone, or in combination with antibiotics, inhibited the proliferation of ISP479C in chamber fluid or SEVs over the initial 4-h period (P < 0.05 versus controls). Moreover, nafcillin-containing regimens exerted inhibitory effects beyond 4 h against ISP479C in both model phases. By comparison, activated platelets inhibited GISA-NJ proliferation in SEVs but not in chamber fluid. The combination of platelets plus nafcillin or vancomycin significantly inhibited proliferation of the GISA-NJ strain in SEVs compared to the effect of platelets or antibiotics alone (P < 0.05). In contrast, platelets did not significantly alter the antistaphylococcal efficacies of nafcillin or vancomycin against ISP479R. These data support our hypothesis that a beneficial antimicrobial effect may result from the interaction among platelets, PMPs, and anti-infective agents against antibiotic-susceptible or -resistant staphylococci that exhibit a tPMP-1-susceptible or -intermediate-susceptible phenotype.

Pharmacokinetically-based prediction of the effects of antibiotic combinations on resistant Staphylococcus aureus mutants: in vitro model studies with linezolid and rifampicin

2016 ◽  
Vol 29 (4) ◽  
pp. 220-226 ◽  
Author(s):  
Alexander A. Firsov ◽  
Maria V. Golikova ◽  
Elena N. Strukova ◽  
Yury A. Portnoy ◽  
Svetlana A. Dovzhenko ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
In Vitro Model ◽  
Model Studies ◽  
Vitro Model

scholarly journals In Vitro Evaluation of the Activities of Telavancin, Cefazolin, and Vancomycin against Methicillin-Susceptible and Methicillin-Resistant Staphylococcus aureus in Peritoneal Dialysate

2007 ◽  
Vol 51 (12) ◽  
pp. 4521-4524 ◽  
Author(s):  
Frances L. Clouse ◽  
Laurie B. Hovde ◽  
John C. Rotschafer
Keyword(s):  
Staphylococcus Aureus ◽  
Peritoneal Dialysis ◽  
In Vitro Model ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Dialysis Fluid ◽  
Methicillin Resistant ◽  
Peritoneal Dialysate ◽  
Peritoneal Dialysis Fluid ◽  
Vitro Model

ABSTRACT This study compared the ability of telavancin to the ability of cefazolin and vancomycin to eliminate staphylococci from peritoneal dialysis fluid by using a static in vitro model to simulate the conditions of peritoneal dialysis. The results showed that telavancin exhibited statistically significantly better kill (P < 0.05) against both methicillin-susceptible and methicillin-resistant Staphylococcus aureus.

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