scholarly journals In Vitro Activities of Fluoroquinolones against Antibiotic-Resistant Blood Culture Isolates of Viridans Group Streptococci from across Canada

1999 ◽  
Vol 43 (9) ◽  
pp. 2299-2301 ◽  
Author(s):  
J. C. S. de Azavedo ◽  
L. Trpeski ◽  
S. Pong-Porter ◽  
S. Matsumura ◽  
D. E. Low
Keyword(s):  
Blood Culture ◽  
Streptococcus Mitis ◽  
Antibiotic Resistant ◽  
Streptococcus Sanguis ◽  
Viridans Group Streptococci

ABSTRACT Among 418 blood culture isolates of viridans group streptococci obtained between 1995 and 1997, the in vitro rates of nonsusceptibility to penicillin, erythromycin, tetracycline, and trimethoprim-sulfamethoxazole were 28, 29, 24, and 14%, respectively. The most prevalent group (125 strains) was Streptococcus mitis, followed by Streptococcus sanguis (56 strains). For 236 (56%) strains resistant to one or more antibiotics, the ciprofloxacin MIC at which 90% of the isolates were inhibited (MIC90) was 4 μg/ml, whereas the MIC90s of trovafloxacin, grepafloxacin, and gatifloxacin were 0.25 μg/ml.

scholarly journals Efficacy of Trovafloxacin in Treatment of Experimental Staphylococcal or Streptococcal Endocarditis

1999 ◽  
Vol 43 (1) ◽  
pp. 77-84 ◽  
Author(s):  
J. M. Entenza ◽  
J. Vouillamoz ◽  
M. P. Glauser ◽  
P. Moreillon
Keyword(s):  
Staphylococcus Aureus ◽  
Oral Dose ◽  
Experimental Model ◽  
Streptococcus Mitis ◽  
Control Drug ◽  
Streptococcus Sanguis ◽  
Viridans Group Streptococci ◽  
Higher Doses

ABSTRACT The efficacy of trovafloxacin against Staphylococcus aureus and viridans group streptococci was investigated in vitro and in an experimental model of endocarditis. The MICs at which trovafloxacin and ciprofloxacin inhibited 90% of clinical isolates of such bacteria (MIC90s) were (i) 0.03 and 2 mg/liter, respectively, for 30 ciprofloxacin-susceptible S. aureus isolates, (ii) 32 and 128 mg/liter, respectively, for 20 ciprofloxacin-resistant S. aureus isolates, and (iii) 0.25 and 8 mg/liter, respectively, for 28 viridans group streptococci. Rats with aortic vegetations were infected with either of two ciprofloxacin-susceptible but methicillin-resistant S. aureus strains (strains COL and P8), one penicillin-susceptibleStreptococcus sanguis strain, or one penicillin-resistantStreptococcus mitis strain. Rats were treated for 3 or 5 days with doses that resulted in kinetics that simulated those achieved in humans with trovafloxacin (200 mg orally once a day), ciprofloxacin (750 mg orally twice a day), vancomycin (1 g intravenously twice a day), or ceftriaxone (2 g intravenously once a day). Against the staphylococci, the activities of both trovafloxacin and ciprofloxacin were equivalent to that of vancomycin, and treatment of endocarditis with these drugs was successful (P < 0.05). However, ciprofloxacin selected for resistant derivatives in vitro and in vivo, whereas trovafloxacin was 10 to 100 times less prone than ciprofloxacin to select for resistance in vitro and did not select for resistance in vivo. Against the two streptococcal isolates, trovafloxacin significantly (P < 0.05) decreased bacterial counts in the vegetations but was less effective than the control drug, ceftriaxone. Thus, a simulated oral dose of trovafloxacin (200 mg per day) was effective against ciprofloxacin-susceptible staphylococci and was less likely than ciprofloxacin to select for resistance. The simulated oral dose of trovafloxacin also had some activity against streptococcal endocarditis, but optimal treatment of infections caused by such organisms might require higher doses of the drug.

scholarly journals Strain-Specific Adaptations of Streptococcus mitis-oralis to Serial In Vitro Passage in Daptomycin (DAP): Genotypic and Phenotypic Characteristics

Antibiotics ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 520
Author(s):  
Nagendra N. Mishra ◽  
Truc T. Tran ◽  
Cesar A. Arias ◽  
Ravin Seepersaud ◽  
Paul M. Sullam ◽  
...  
Keyword(s):  
Surface Charge ◽  
Membrane Fluidity ◽  
Nucleotide Polymorphisms ◽  
Membrane Phospholipids ◽  
Streptococcus Mitis ◽  
Positive Surface Charge ◽  
Identical Manner ◽  
High Level ◽  
Viridans Group Streptococci

Viridans group streptococci (VGS), especially the Streptococcus mitis-oralis subgroup, are pivotal pathogens in a variety of invasive endovascular infections, including “toxic shock” in neutropenic cancer patients and infective endocarditis (IE). Previously, we showed that the serial in vitro passage of S. mitis-oralis strains in sublethal daptomycin (DAP) resulted in rapid, high-level and stable DAP-resistance (DAP-R), which is accompanied by distinct changes in several genotypic and phenotypic signatures: (1) the disappearance of two key membrane phospholipids, phosphatidylglycerol (PG) and cardiolipin (CL); (2) increased membrane fluidity; (3) increased positive surface charge; (4) single nucleotide polymorphisms (SNPs) in two loci involved in CL biosynthesis (pgsA; cdsA); and (5) DAP hyperaccumulation. The current study examined these same metrics following in vitro serial DAP passages of a separate well-characterized S. mitis-oralis bloodstream isolate (SF100). Although some metrics seen in prior DAP post-passage strains were recapitulated with SF100 (e.g., pgsA SNPs, enhanced membrane fluidity), we observed the following major differences (comparing the parental versus post-passage variant): (1) no change in PG content; (2) reduced, but not absent, CL, with enhancement in phosphatidic acid (PA) content; (3) an unusual pattern of CL localization; (4) significantly decreased positive surface charge; (5) no difference in DAP accumulation; and (6) no cdsA SNPs. Thus, S. mitis-oralis strains are not “pre-programmed” phenotypically and/or genotypically to adapt in an identical manner during the evolution of the DAP-R.

scholarly journals Mutations in cdsA and pgsA Correlate with Daptomycin Resistance in Streptococcus mitis and S. oralis

2018 ◽  
Vol 63 (2) ◽  
pp. e01531-18 ◽  
Author(s):  
Truc T. Tran ◽  
Nagendra N. Mishra ◽  
Ravin Seepersaud ◽  
Lorena Diaz ◽  
Rafael Rios ◽  
...  
Keyword(s):  
Cell Membrane ◽  
Cell Membranes ◽  
Complete Disappearance ◽  
Biosynthesis Pathway ◽  
Streptococcus Mitis ◽  
Content Type ◽  
High Level ◽  
Viridans Group Streptococci

ABSTRACT We investigated the ability of several recent clinical viridans group streptococci (VGS) bloodstream isolates (Streptococcus mitis/S. oralis subgroup) from daptomycin (DAP)-naive patients to develop DAP resistance in vitro. All strains rapidly developed high-level and stable DAP resistance. Substitutions in two enzymes involved in the cardiolipin biosynthesis pathway were identified, i.e., CdsA (phosphatidate cytidylyltransferase) and PgsA (CDP-diacylglycerol-glycerol-3-phosphate-3-phosphatidyltransferase). These mutations were associated with complete disappearance of phosphatidylglycerol and cardiolipin from cell membranes. DAP interactions with the cell membrane differed in isolates with PgsA versus CdsA substitutions.

scholarly journals Daptomycin Dose-Ranging Evaluation with Single-Dose versus Multidose Ceftriaxone Combinations against Streptococcus mitis/oralis in an Ex Vivo Simulated Endocarditis Vegetation Model

2019 ◽  
Vol 63 (6) ◽  
Author(s):  
Razieh Kebriaei ◽  
Seth A. Rice ◽  
Kyle C. Stamper ◽  
Ravin Seepersaud ◽  
Cristina Garcia-de-la-Maria ◽  
...  
Keyword(s):  
Single Dose ◽  
Ex Vivo ◽  
Therapeutic Option ◽  
Streptococcus Mitis ◽  
Oral Flora ◽  
Content Type ◽  
High Level ◽  
Viridans Group Streptococci ◽  
Combination Regimens

ABSTRACT The viridans group streptococci (VGS) are a heterogeneous group of organisms which are important components of the normal human oral flora. Among the VGS, the Streptococcus mitis/oralis subgroup is one of the most common causes of infective endocarditis (IE). Daptomycin (DAP) is a potential alternative therapeutic option for invasive S. mitis infections, given high rates of β-lactam resistance and vancomycin tolerance in such strains. However, the ability of these strains to rapidly evolve high-level and durable DAP resistance (DAP-R) is problematic. Recent data suggest that combination DAP-β-lactam therapy circumvents this issue. Human-simulated dose-escalating DAP-alone dose regimens (6, 8, 10, or 12 mg/kg/day times 4 days) versus DAP (6 mg/kg/day) plus ceftriaxone (CRO) (2 g once daily times 4 days or 0.5 g, single dose) were assessed against two prototypical DAP-susceptible (DAP-S) S. mitis/oralis strains (SF100 and 351), as measured by a pharmacokinetic/pharmacodynamic (PK/PD) model of simulated endocardial vegetations (SEVs). No DAP-alone regimen was effective, with regrowth of high-level DAP-R isolates observed for both strains over 96-h exposures. Combinations of DAP-CRO with either single- or multidose regimens yielded significant reductions in log10 CFU/g amounts within SEVs for both strains (∼6 log10 CFU/g) within 24 h. In addition, no DAP-R strains were detected in either DAP-CRO combination regimens over the 96-h exposure. In contrast to prior in vitro studies, no perturbations in two key cardiolipin biosynthetic genes (cdsA and pgsA) were identified in DAP-R SEV isolates emerging from strain 351, despite defective phospholipid production. The combination of DAP-CRO warrants further investigation for treatment of IE due to S. mitis/oralis.

scholarly journals Impact of High-Level Daptomycin Resistance in the Streptococcus mitis Group on Virulence and Survivability during Daptomycin Treatment in Experimental Infective Endocarditis

2017 ◽  
Vol 61 (5) ◽  
Author(s):  
C. Garcia-de-la-Maria ◽  
Y. Q. Xiong ◽  
J. M. Pericas ◽  
Y. Armero ◽  
A. Moreno ◽  
...  
Keyword(s):  
Infective Endocarditis ◽  
Parental Strain ◽  
Durable Resistance ◽  
Relative Fitness ◽  
Streptococcus Mitis ◽  
Content Type ◽  
Target Organs ◽  
High Level ◽  
Viridans Group Streptococci

ABSTRACT Among the viridans group streptococci, the Streptococcus mitis group is the most common cause of infective endocarditis. These bacteria have a propensity to be β-lactam resistant, as well as to rapidly develop high-level and durable resistance to daptomycin (DAP). We compared a parental, daptomycin-susceptible (DAPs) S. mitis/S. oralis strain and its daptomycin-resistant (DAPr) variant in a model of experimental endocarditis in terms of (i) their relative fitness in multiple target organs in this model (vegetations, kidneys, spleen) when animals were challenged individually and in a coinfection strategy and (ii) their survivability during therapy with daptomycin-gentamicin (an in vitro combination synergistic against the parental strain). The DAPr variant was initially isolated from the cardiac vegetations of animals with experimental endocarditis caused by the parental DAPs strain following treatment with daptomycin. The parental strain and the DAPr variant were comparably virulent when animals were individually challenged. In contrast, in the coinfection model without daptomycin therapy, at both the 106- and 107-CFU/ml challenge inocula, the parental strain outcompeted the DAPr variant in all target organs, especially the kidneys and spleen. When the animals in the coinfection model of endocarditis were treated with DAP-gentamicin, the DAPs strain was completely eliminated, while the DAPr variant persisted in all target tissues. These data underscore that the acquisition of DAPr in S. mitis/S. oralis does come at an intrinsic fitness cost, although this resistance phenotype is completely protective against therapy with a potentially synergistic DAP regimen.

scholarly journals Trovafloxacin Treatment of Viridans Group Streptococcus Experimental Endocarditis

2000 ◽  
Vol 44 (9) ◽  
pp. 2554-2556 ◽  
Author(s):  
Kerryl E. Piper ◽  
Mark S. Rouse ◽  
Karen L. Ronningen ◽  
James M. Steckelberg ◽  
Walter R. Wilson ◽  
...  
Keyword(s):  
Body Weight ◽  
Aortic Valve ◽  
Similar Efficacy ◽  
Species Group ◽  
Streptococcus Mitis ◽  
Streptococcus Sanguis ◽  
Serious Infections ◽  
Viridans Group Streptococcus ◽  
Viridans Group Streptococci

ABSTRACT The activity of trovafloxacin was compared with those of vancomycin and penicillin in a model of Streptococcus sanguis species group (trovafloxacin MIC, 0.125 μg/ml) and Streptococcus mitis species group (trovafloxacin MIC, 0.125 μg/ml) experimental endocarditis. Rabbits with catheter-induced aortic valve vegetations were given no treatment, trovafloxacin at 15 mg/kg of body weight three times a day (t.i.d.), vancomycin at 15 mg/kg twice a day, or penicillin at 1.2 × 106 IU t.i.d. After 3 days of treatment, the animals were sacrificed; cardiac valve vegetations were aseptically removed and cultured quantitatively. Penicillin was as active as vancomycin as measured by in vivo clearance of bacteria. Trovafloxacin was less active (P < 0.05) than vancomycin or penicillin against S. sanguis species group infection but had similar efficacy against S. mitis species group infection. Quinolones, despite MICs in the susceptible range, may not be active for serious infections caused by some viridans group streptococci.

scholarly journals The Efficacy of Neem Extract on Four Microorganisms Responsible for causing Dental Caries viz Streptococcus mutans, Streptococcus salivarius, Streptococcus mitis and Streptococcus sanguis: An in vitro Study

2012 ◽  
Vol 13 (6) ◽  
pp. 769-772 ◽  
Author(s):  
Venkateswara Rao Chava ◽  
SM Manjunath ◽  
AV Rajanikanth ◽  
N Sridevi
Keyword(s):  
Dental Caries ◽  
Streptococcus Mutans ◽  
Dietary Habits ◽  
Individual Species ◽  
Streptococcus Salivarius ◽  
Streptococcus Mitis ◽  
Neem Extract ◽  
Coarse Powder ◽  
Streptococcus Sanguis

ABSTRACT History and objectives From the ancient time, neem used to be the traditional medicine for many diseases and was mainly used for cleaning the oral cavity. The incidence of dental caries was less a few decades ago but now the incidence of caries is very aggressive. This might be due to change in dietary habits, life style and more tendency toward processed food. The objective of this study is to find out the truth that if the neem is really efficacious against caries-inducing microorganisms, mainly Streptococcus mutans, Streptococcus salivarius, Streptococcus mitis and Streptococcus sanguis. Materials and methods The dried neem sticks ground into a coarse powder and weighed into 5, 10 and 50 gm were added to 100 ml of deionized double distilled water. After soaking for 2 days, the water was filtered at 4°C and the fine filtrate was inoculated onto blood agar plates contains individual species of microorganisms and incubated at 37°C for 2 days. Results At maximum concentrations, neem extract has shown the maximum zone of inhibition on Streptococcus mutans. At less concentration, the efficacy of neem has shown some inhibition of growth for all the four species of microorganisms. Conclusion Neem chewing provides the maximum benefits. Hence, the use of chewing sticks of neem can be recommended. How to cite this article Chava VR, Manjunath SM, Rajanikanth AV, Sridevi N. The Efficacy of Neem Extract on Four Microorganisms Responsible for causing Dental Caries viz Streptococcus mutans, Streptococcus salivarius, Streptococcus mitis, and Streptococcus sanguis: An in vitro Study. J Contemp Dent Pract 2012;13(6):769-772.

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