scholarly journals In vivo emergence of subpopulations expressing teicoplanin or vancomycin resistance phenotypes in a glycopeptide-susceptible, methicillin-resistant strain of Staphylococcus aureus

2001 ◽  
Vol 47 (2) ◽  
pp. 163-170 ◽  
Author(s):  
P. Vaudaux
Keyword(s):  
Staphylococcus Aureus ◽  
Resistant Strain ◽  
Vancomycin Resistance ◽  
Methicillin Resistant

scholarly journals Comparison of the postantibiotic and postantibiotic sub-MIC effects of levofloxacin and ciprofloxacin on Staphylococcus aureus and Streptococcus pneumoniae.

1997 ◽  
Vol 41 (5) ◽  
pp. 950-955 ◽  
Author(s):  
L Licata ◽  
C E Smith ◽  
R M Goldschmidt ◽  
J F Barrett ◽  
M Frosco
Keyword(s):  
Staphylococcus Aureus ◽  
Streptococcus Pneumoniae ◽  
Resistant Strain ◽  
Drug Exposure ◽  
Inhibitory Concentration ◽  
Resistant Isolate ◽  
Postantibiotic Effect ◽  
Methicillin Resistant ◽  
Susceptible Isolate

The postantibiotic subminimum inhibitory concentration effect (PA SME) may simulate in vivo drug exposure more accurately than the postantibiotic effect (PAE) since subinhibitory concentrations of drug persist between antibiotic dosings. In this study, we compared the PAEs and PA SMEs of levofloxacin and ciprofloxacin for clinical isolates of fluoroquinolone-susceptible Staphylococcus aureus and Streptococcus pneumoniae. At two times the MIC, PAEs of levofloxacin were an average of 0.6 h longer than the PAEs obtained for ciprofloxacin for methicillin-susceptible and methicillin-resistant S. aureus strains. The PAEs of levofloxacin and ciprofloxacin ranged from 1.8 to 3.1 and 1.1 to 2.4 h, respectively. Continued exposure of the methicillin-resistant strain to 1/16, 1/8, and 1/4 the MIC resulted in PA SMEs of 6.5, 15.3, and >22.3 h, respectively, for levofloxacin and 3.8, 8.0, and 12.3 h, respectively, for ciprofloxacin. For isolates of S. pneumoniae, at two times the MIC of both fluoroquinolones, the average PAEs of levofloxacin and ciprofloxacin were equivalent: 1.3 h for the penicillin-susceptible isolate and 0.6 h for the penicillin-resistant isolate. Continued exposure of the penicillin-susceptible S. pneumoniae strain to 1/16, 1/8, and 1/4 the MIC resulted in average PA SMEs of 1.0, 1.4, and 2.8 h, respectively, for levofloxacin and 1.8, 2.0, and 2.5 h, respectively, for ciprofloxacin. Continued exposure of penicillin-resistant S. pneumoniae to 1/16, 1/8, and 1/4 the MIC of the same fluoroquinolones resulted in average PA SMEs of 0.6, 1.1, and 2.9 h, respectively, for levofloxacin and 0.6, 1.1, and 1.5 h, respectively, for ciprofloxacin. The PA SMEs observed demonstrate the superior activity of levofloxacin against methicillin-susceptible or methicillin-resistant S. aureus. Although PAEs were similar for the penicillin-susceptible and penicillin-resistant S. pneumoniae strains, the PA SME of levofloxacin at one-fourth the MIC was longer for penicillin-resistant S. pneumoniae.

scholarly journals Efficacy of Levofloxacin for Experimental Aortic-Valve Endocarditis in Rabbits Infected with Viridans Group Streptococcus or Staphylococcus aureus

1999 ◽  
Vol 43 (11) ◽  
pp. 2742-2746 ◽  
Author(s):  
Henry F. Chambers ◽  
Qing Xiang ◽  
Liu ◽  
Lucian Liuxin Chow ◽  
Corinne Hackbarth
Keyword(s):  
Staphylococcus Aureus ◽  
Aortic Valve ◽  
Resistant Strain ◽  
Single Agent ◽  
Rabbit Model ◽  
Susceptible Strain ◽  
Methicillin Resistant ◽  
Days Of Therapy

ABSTRACT Levofloxacin is among the more active fluoroquinolones against streptococci and staphylococci. It is effective against moderately severe infections caused by these organisms, but its efficacy in the treatment of bacteremia and serious infections such as endocarditis is not well defined. We compared the efficacy of levofloxacin to those of standard agents in the rabbit model of aortic-valve endocarditis caused by fluoroquinolone-susceptible strains including a penicillin-susceptible strain of Streptococcus sanguis, a penicillin-resistant strain of Streptococcus mitis, a methicillin-resistant strain of Staphylococcus aureus, and a methicillin-susceptible strain of S. aureus. Levofloxacin administered intramuscularly at dosages of 20 to 40 mg/kg of body weight twice daily (b.i.d.) was completely ineffective against the penicillin-susceptible strain, with mean vegetation titers after 3 days of therapy not statistically significantly different from those for controls. Levofloxacin was no more effective than penicillin against the penicillin-resistant strain. Levofloxacin administered for 4 days at a dosage of 20 mg/kg b.i.d. was at least as effective as vancomycin administered intravenously at a dosage of 25 mg/kg b.i.d. against the methicillin-resistant S. aureus strain and was as effective as nafcillin administered intramuscularly at 100 mg three times daily against the methicillin-susceptible strain. Emergence of resistance to levofloxacin in vitro was less likely to occur than resistance to ciprofloxacin, and resistance to levofloxacin was not observed in vivo. Levofloxacin-rifampin combinations were antagonistic in vitro and in vivo. Levofloxacin was highly effective as a single agent against experimental staphylococcal endocarditis but was surprisingly ineffective against streptococcal endocarditis, suggesting that it has a potential role as treatment for serious S. aureus but not viridans group streptococcal infections in humans.

scholarly journals Group V Phospholipase A2 Mediates Endothelial Dysfunction and Acute Lung Injury Caused by Methicillin-Resistant Staphylococcus aureus

Cells ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1731
Author(s):  
Yu Maw Htwe ◽  
Huashan Wang ◽  
Patrick Belvitch ◽  
Lucille Meliton ◽  
Mounica Bandela ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Acute Lung Injury ◽  
Endothelial Dysfunction ◽  
Lung Injury ◽  
Phospholipase A2 ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Group V ◽  
Methicillin Resistant

Lung endothelial dysfunction is a key feature of acute lung injury (ALI) and clinical acute respiratory distress syndrome (ARDS). Previous studies have identified the lipid-generating enzyme, group V phospholipase A2 (gVPLA2), as a mediator of lung endothelial barrier disruption and inflammation. The current study aimed to determine the role of gVPLA2 in mediating lung endothelial responses to methicillin-resistant Staphylococcus aureus (MRSA, USA300 strain), a major cause of ALI/ARDS. In vitro studies assessed the effects of gVPLA2 inhibition on lung endothelial cell (EC) permeability after exposure to heat-killed (HK) MRSA. In vivo studies assessed the effects of intratracheal live or HK-MRSA on multiple indices of ALI in wild-type (WT) and gVPLA2-deficient (KO) mice. In vitro, HK-MRSA increased gVPLA2 expression and permeability in human lung EC. Inhibition of gVPLA2 with either the PLA2 inhibitor, LY311727, or with a specific monoclonal antibody, attenuated the barrier disruption caused by HK-MRSA. LY311727 also reduced HK-MRSA-induced permeability in mouse lung EC isolated from WT but not gVPLA2-KO mice. In vivo, live MRSA caused significantly less ALI in gVPLA2 KO mice compared to WT, findings confirmed by intravital microscopy assessment in HK-MRSA-treated mice. After targeted delivery of gVPLA2 plasmid to lung endothelium using ACE antibody-conjugated liposomes, MRSA-induced ALI was significantly increased in gVPLA2-KO mice, indicating that lung endothelial expression of gVPLA2 is critical in vivo. In summary, these results demonstrate an important role for gVPLA2 in mediating MRSA-induced lung EC permeability and ALI. Thus, gVPLA2 may represent a novel therapeutic target in ALI/ARDS caused by bacterial infection.

scholarly journals In Vitro and In Vivo Activities of DA-7867, a New Oxazolidinone, against Aerobic Gram-Positive Bacteria

2005 ◽  
Vol 49 (6) ◽  
pp. 2498-2500 ◽  
Author(s):  
Eun Jeong Yoon ◽  
Yeong Woo Jo ◽  
Sung Hak Choi ◽  
Tae Ho Lee ◽  
Jae Keol Rhee ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Streptococcus Pneumoniae ◽  
Gram Positive ◽  
Methicillin Resistant ◽  
Gram Positive Bacteria ◽  
Vancomycin Resistant Enterococci ◽  
Infection Models ◽  
Vancomycin Resistant

ABSTRACT In vitro and in vivo activities of DA-7867 were assessed against methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, and penicillin-resistant Streptococcus pneumoniae. All isolates were inhibited by DA-7867 at ≤0.78 μg/ml, a four-times-lower concentration than that of inhibition by linezolid. For murine infection models, DA-7867 also exhibited greater efficacy than linezolid against all isolates tested.

Recurrent Methicillin-Resistant Staphylococcus Aureus Osteomyelitis: Combination Antibiotic Therapy with Evaluation by Serum Bactericidal Titers

1995 ◽  
Vol 29 (7-8) ◽  
pp. 694-697 ◽  
Author(s):  
Sherrie L Aspinall ◽  
David M Friedland ◽  
Victor L Yu ◽  
John D Rihs ◽  
Robert R Muder
Keyword(s):  
Staphylococcus Aureus ◽  
Back Pain ◽  
Antibiotic Therapy ◽  
Sedimentation Rate ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Blood Cultures ◽  
Low Back ◽  
Methicillin Resistant ◽  
Trough Concentrations

Objective: To report on a patient with recurrent methicillin-resistant Staphylococcus aureus (MRSA) osteomyelitis and bacteremia successfully treated with combination antibiotic therapy. Case Summary: Two sets of blood cultures from a 55-year-old man with fever, malaise, and low back pain grew MRSA. Radiologic studies of the spine showed bony changes consistent with osteomyelitis. Soon after completing 6 weeks of vancomycin, the patient experienced a recurrence of back pain. Laboratory values included an increase in the sedimentation rate to 53 mm/h and positive blood cultures for MRSA. Vancomycin, gentamicin, and rifampin were administered for 8 weeks. Serum inhibitory and bactericidal titers were more than 1:1024 for both the peak and trough concentrations. Radiologic studies of the spine showed healing osteomyelitis. Two years after completion of antibiotic therapy, the infection has not recurred. Discussion: Antibiotic therapy alone was attempted because the patient was considered a risky surgical candidate. Serum inhibitory and bactericidal titers documented the high in vivo activity of the vancomycin, gentamicin, and rifampin combination. Initiation of vancomycin therapy led to disappearance of the fever and back pain. Cure was documented by sustained normalization of the erythrocyte sedimentation rate and radiologic evidence of healing. Conclusions: Combination antibiotic therapy with vancomycin, rifampin, and low-dose gentamicin (1 mg/kg q12h) may be useful for deep-seated tissue infection caused by MRSA.

scholarly journals Discovery of genes encoding a Streptolysin S-like toxin biosynthetic cluster in a select highly pathogenic methicillin resistant Staphylococcus aureus JKD6159 strain

2019 ◽  
Author(s):  
Trevor Kane ◽  
Katelyn E. Carothers ◽  
Yunjuan Bao ◽  
Won-Sik Yeo ◽  
Taeok Bae ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Gene Cluster ◽  
Virulence Factor ◽  
Gene Organization ◽  
Biosynthetic Gene ◽  
Bacterial Gene ◽  
Methicillin Resistant ◽  
Streptolysin S

AbstractBackgroundStaphylococcus aureus (S. aureus) is a major human pathogen owing to its arsenal of virulence factors, as well as its acquisition of multi-antibiotic resistance. Here we report the identification of a Streptolysin S (SLS) like biosynthetic gene cluster in a highly virulent community-acquired methicillin resistant S. aureus (MRSA) isolate, JKD6159. Examination of the SLS-like gene cluster in JKD6159 shows significant homology and gene organization to the SLS-associated biosynthetic gene (sag) cluster responsible for the production of the major hemolysin SLS in Group A Streptococcus.ResultsWe took a comprehensive approach to elucidating the putative role of the sag gene cluster in JKD6159 by constructing a mutant in which one of the biosynthesis genes (sagB homologue) was deleted in the parent JKD6159 strain. Assays to evaluate bacterial gene regulation, biofilm formation, antimicrobial activity, as well as complete host cell response profile and comparative in vivo infections in Balb/Cj mice were conducted.ConclusionsAlthough no significant phenotypic changes were observed in our assays, we postulate that the SLS-like toxin produced by this strain of S. aureus may be a highly specialized virulence factor utilized in specific environments for selective advantage; studies to better understand the role of this newly discovered virulence factor in S. aureus warrant further investigation.

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