scholarly journals Efficacy of a New Fluoroquinolone, JNJ-Q2, in Murine Models of Staphylococcus aureus and Streptococcus pneumoniae Skin, Respiratory, and Systemic Infections

2011 ◽  
Vol 55 (12) ◽  
pp. 5522-5528 ◽  
Author(s):  
Jeffrey Fernandez ◽  
Jamese J. Hilliard ◽  
Brian J. Morrow ◽  
John L. Melton ◽  
Robert K. Flamm ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Streptococcus Pneumoniae ◽  
Tract Infection ◽  
Lower Respiratory Tract ◽  
Skin Infection ◽  
Infection Model ◽  
Content Type ◽  
Infection Models ◽  
Resistant Mutants ◽  
Selection Of

ABSTRACTThein vivoefficacy of JNJ-Q2, a new broad-spectrum fluoroquinolone (FQ), was evaluated in a murine septicemia model with methicillin-susceptibleStaphylococcus aureus(MSSA) and methicillin-resistantS. aureus(MRSA) and in aStreptococcus pneumoniaelower respiratory tract infection model. JNJ-Q2 and comparators were also evaluated in an acute murine skin infection model using a community-acquired MRSA strain and in an established skin infection (ESI) model using a hospital-acquired strain, for which the selection of resistant mutants was also determined. JNJ-Q2 demonstrated activity in the MSSA septicemia model that was comparable to that moxifloxacin (JNJ-Q2 50% effective dose [ED50], 0.2 mg/kg of body weight administered subcutaneously [s.c.] and 2 mg/kg administered orally [p.o.]) and activity in the MRSA septicemia model that was superior to that of vancomycin (JNJ-Q2 ED50, 1.6 mg/kg administered s.c.). In anS. pneumoniaelower respiratory tract infection model, JNJ-Q2 displayed activity (ED50, 1.9 mg/kg administered s.c. and 7.4 mg/kg administered p.o.) that was comparable to that of gemifloxacin and superior to that of moxifloxacin. In both MRSA skin infection models, treatment with JNJ-Q2 resulted in dose-dependent reductions in bacterial titers in the skin, with the response to JNJ-Q2 at each dose exceeding the responses of the comparators ciprofloxacin, moxifloxacin, linezolid, and vancomycin. Additionally, in the ESI model, JNJ-Q2 showed a low or nondetectable propensity for ciprofloxacin resistance selection, in contrast to the selection of ciprofloxacin-resistant mutants observed for both ciprofloxacin and moxifloxacin. JNJ-Q2 demonstrated activity that was comparable or superior to the activity of fluoroquinolone or antistaphylococcal comparators in several local and systemic skin infection models performed with bothS. aureusandS. pneumoniaeand is currently being evaluated in phase II human clinical trials.

scholarly journals The Two-Component System GrvRS (EtaRS) RegulatesaceExpression in Enterococcus faecalis OG1RF

2014 ◽  
Vol 83 (1) ◽  
pp. 389-395 ◽  
Author(s):  
Jung Hyeob Roh ◽  
Kavindra V. Singh ◽  
Sabina Leanti La Rosa ◽  
Ana Luisa V. Cohen ◽  
Barbara E. Murray
Keyword(s):  
Urinary Tract Infection ◽  
Urinary Tract ◽  
Tract Infection ◽  
Regulatory System ◽  
Northern Hybridization ◽  
Infection Model ◽  
Content Type ◽  
Infection Models ◽  
Two Component ◽  
Main Regulator

Expression oface(adhesin tocollagen ofEnterococcus faecalis), encoding a virulence factor in endocarditis and urinary tract infection models, has been shown to increase under certain conditions, such as in the presence of serum, bile salts, urine, and collagen and at 46°C. However, the mechanism oface/Ace regulation under different conditions is still unknown. In this study, we identified a two-component regulatory system GrvRS as the main regulator ofaceexpression under these stress conditions. Using Northern hybridization and β-galactosidase assays of anacepromoter-lacZfusion, we found transcription ofaceto be virtually absent in agrvRdeletion mutant under the conditions that increaseaceexpression in wild-type OG1RF and in the complemented strain. Moreover, agrvRmutant revealed decreased collagen binding and biofilm formation as well as attenuation in a murine urinary tract infection model. Here we show that GrvR plays a major role in control ofaceexpression andE. faecalisvirulence.

scholarly journals In VivoPharmacodynamic Target Assessment of Delafloxacin against Staphylococcus aureus, Streptococcus pneumoniae, and Klebsiella pneumoniae in a Murine Lung Infection Model

2016 ◽  
Vol 60 (8) ◽  
pp. 4764-4769 ◽  
Author(s):  
Alexander J. Lepak ◽  
David R. Andes
Keyword(s):  
Staphylococcus Aureus ◽  
Single Dose ◽  
Streptococcus Pneumoniae ◽  
Klebsiella Pneumoniae ◽  
Dose Response ◽  
Lung Infection ◽  
Infection Model ◽  
Content Type ◽  
Murine Lung

ABSTRACTDelafloxacin is a broad-spectrum anionic fluoroquinolone under development for the treatment of bacterial pneumonia. The goal of the study was to determine the pharmacokinetic/pharmacodynamic (PK/PD) targets in the murine lung infection model forStaphylococcus aureus,Streptococcus pneumoniae, andKlebsiella pneumoniae. Four isolates of each species were utilized forin vivostudies: forS. aureus, one methicillin-susceptible and three methicillin-resistant isolates;S. pneumoniae, two penicillin-susceptible and two penicillin-resistant isolates;K. pneumoniae, one wild-type and three extended-spectrum beta-lactamase-producing isolates. MICs were determined using CLSI methods. A neutropenic murine lung infection model was utilized for all treatment studies, and drug dosing was by the subcutaneous route. Single-dose plasma pharmacokinetics was determined in the mouse model after administration of 2.5, 10, 40, and 160 mg/kg. Forin vivostudies, 4-fold-increasing doses of delafloxacin (range, 0.03 to 160 mg/kg) were administered every 6 h (q6h) to infected mice. Treatment outcome was measured by determining organism burden in the lung (CFU counts) at the end of each experiment (24 h). The Hill equation for maximum effect (Emax) was used to model the dose-response data. The magnitude of the PK/PD index, the area under the concentration-time curve over 24 h in the steady state divided by the MIC (AUC/MIC), associated with net stasis and 1-log kill endpoints was determined in the lung model for all isolates. MICs ranged from 0.004 to 1 mg/liter. Single-dose PK parameter ranges include the following: for maximum concentration of drug in serum (Cmax), 2 to 70.7 mg/liter; AUC from 0 h to infinity (AUC0–∞), 2.8 to 152 mg · h/liter; half-life (t1/2), 0.7 to 1 h. At the start of therapy mice had 6.3 ± 0.09 log10CFU/lung. In control mice the organism burden increased 2.1 ± 0.44 log10CFU/lung over the study period. There was a relatively steep dose-response relationship observed with escalating doses of delafloxacin. Maximal organism reductions ranged from 2 log10to more than 4 log10. The median free-drug AUC/MIC magnitude associated with net stasis for each species group was 1.45, 0.56, and 40.3 forS. aureus,S. pneumoniae, andK. pneumoniae, respectively. AUC/MIC targets for the 1-log kill endpoint were 2- to 5-fold higher. Delafloxacin demonstratedin vitroandin vivopotency against a diverse group of pathogens, including those with phenotypic drug resistance to other classes. These results have potential relevance for clinical dose selection and evaluation of susceptibility breakpoints for delafloxacin for the treatment of lower respiratory tract infections involving these pathogens.

scholarly journals In VivoPharmacodynamic Target Investigation of Two Bacterial Topoisomerase Inhibitors, ACT-387042 and ACT-292706, in the Neutropenic Murine Thigh Model against Streptococcus pneumoniae and Staphylococcus aureus

2016 ◽  
Vol 60 (6) ◽  
pp. 3626-3632 ◽  
Author(s):  
A. J. Lepak ◽  
P. Seiler ◽  
J. P. Surivet ◽  
D. Ritz ◽  
C. Kohl ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Streptococcus Pneumoniae ◽  
Dose Range ◽  
Free Drug ◽  
Infection Model ◽  
Topoisomerase Inhibitors ◽  
Time Curve ◽  
Content Type ◽  
Phenotypic Resistance

ACT-387042 and ACT-292706 are two novel bacterial topoisomerase inhibitors with broad-spectrum activity against Gram-positive and -negative bacteria, including methicillin-resistantStaphylococcus aureusand penicillin- and fluoroquinolone-resistantStreptococcus pneumoniae. We used the neutropenic murine thigh infection model to characterize the pharmacokinetics (PK)/pharmacodynamics (PD) of these investigational compounds against a group of 10S. aureusandS. pneumoniaeisolates with phenotypic resistance to beta-lactams and fluoroquinolones. Thein vitroactivities of the two compounds were very similar (MIC range, 0.03 to 0.125 mg/liter). Plasma pharmacokinetics were determined for each compound by using four escalating doses administered by the subcutaneous route. In treatment studies, mice had 107.4to 108CFU/thigh at the start of therapy with ACT-387042 and 106.7to 108.3CFU/thigh at the start of therapy with ACT-292706. A dose-response relationship was observed with all isolates over the dose range. Maximal kill approached 3 to 4 log10CFU/thigh compared to the burden at the start of therapy for the highest doses examined. There was a strong relationship between the PK/PD index AUC/MIC ratio (area under the concentration-time curve over 24 h in the steady state divided by the MIC) and therapeutic efficacy in the model (R2, 0.63 to 0.82). The 24-h free-drug AUC/MIC ratios associated with net stasis for ACT-387042 againstS. aureusandS. pneumoniaewere 43 and 10, respectively. The 24-h free-drug AUC/MIC ratios associated with net stasis for ACT-292706 againstS. aureusandS. pneumoniaewere 69 and 25, respectively. The stasis PD targets were significantly lower forS. pneumoniae(P< 0.05) for both compounds. The 1-log-kill AUC/MIC ratio targets were ∼2- to 4-fold higher than stasis targets. Methicillin, penicillin, or ciprofloxacin resistance did not alter the magnitude of the AUC/MIC ratio required for efficacy. These results should be helpful in the design of clinical trials for topoisomerase inhibitors.

scholarly journals In VivoAntibacterial Activity of MRX-I, a New Oxazolidinone

2014 ◽  
Vol 58 (4) ◽  
pp. 2418-2421 ◽  
Author(s):  
Cong-Ran Li ◽  
Qian-Qian Zhai ◽  
Xiu-Kun Wang ◽  
Xin-Xin Hu ◽  
Guo-Qing Li ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Streptococcus Pneumoniae ◽  
Local Infection ◽  
Gram Positive ◽  
Methicillin Resistant ◽  
Content Type ◽  
Vancomycin Resistant Enterococci ◽  
Infection Models ◽  
Vancomycin Resistant

ABSTRACTMRX-I is a potent oxazolidinone antibiotic against Gram-positive pathogens, including methicillin-resistantStaphylococcus aureus(MRSA), penicillin-resistantStreptococcus pneumoniae(PRSP), penicillin-intermediateS. pneumoniae(PISP), and vancomycin-resistant enterococci (VRE). In this study, thein vivoefficacy of orally administered MRX-I was evaluated using linezolid as a comparator. MRX-I showed the same or better efficacy than linezolid in both systemic and local infection models against the tested strains.

scholarly journals Pharmacokinetic/Pharmacodynamic Evaluation of a Novel Aminomethylcycline Antibiotic, KBP-7072, in the Neutropenic Murine Pneumonia Model against Staphylococcus aureus and Streptococcus pneumoniae

2018 ◽  
Vol 63 (3) ◽  
Author(s):  
Alexander J. Lepak ◽  
Miao Zhao ◽  
Qingmei Liu ◽  
Ping Wang ◽  
Yanli Wang ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Streptococcus Pneumoniae ◽  
Rational Design ◽  
Dose Range ◽  
Free Drug ◽  
Pharmacokinetic Parameters ◽  
Infection Model ◽  
Time Curve ◽  
Content Type ◽  
Drug Concentrations

ABSTRACT KBP-7072 is a novel aminomethylcycline antibiotic in clinical development for community-acquired pneumonia. The goal of present studies was to determine which pharmacokinetic/pharmacodynamic (PK/PD) parameter magnitude correlated with efficacy in the murine pneumonia infection model against Staphylococcus aureus and Streptococcus pneumoniae. KBP-7072 pharmacokinetic measurements were performed in plasma and epithelial lining fluid (ELF) at 4-fold-increasing doses from 1 to 256 mg/kg of body weight subcutaneously. Pharmacokinetic parameters were calculated using a noncompartmental model and were linear over the dose range. Penetration into ELF ranged from 82% to 238% comparing ELF drug concentrations to plasma free drug concentrations. Twenty-four-hour dose-ranging efficacy studies were then performed in the neutropenic murine pneumonia model against 5 S. aureus (3 methicillin-resistant and 2 methicillin-susceptible) and 6 S. pneumoniae (2 Tetr and 2 Penr) strains. KBP-7072 demonstrated potent in vivo activity resulting in a 3- to 5-log10 kill in CFU burden compared to the start of therapy for all strains. The PK/PD index area under the concentration-time curve (AUC)/MIC corelated well with efficacy (R2, 0.80 to 0.89). Net stasis was achieved at plasma 24-h free drug AUC/MIC values of 1.13 and 1.41 (24-h ELF AUC/MIC values of 2.01 and 2.50) for S. aureus and S. pneumoniae, respectively. A 1-log10 kill was achieved at 24-h plasma AUC/MIC values of 2.59 and 5.67 (24-h ELF AUC/MIC values of 4.22 and 10.08) for S. aureus and S. pneumoniae, respectively. A 2-log10 kill was achieved at 24-h plasma AUC/MIC values of 7.16 and 31.14 (24-h ELF AUC/MIC values of 8.37 and 42.92) for S. aureus and S. pneumoniae, respectively. The results of these experiments will aid in the rational design of dose-finding studies for KBP-7072 in patients with community-acquired bacterial pneumonia (CAP).

scholarly journals In Vivo Pharmacokinetic/Pharmacodynamic Targets of Levonadifloxacin against Staphylococcus aureus in a Neutropenic Murine Lung Infection Model

2019 ◽  
Vol 63 (8) ◽  
Author(s):  
Sachin S. Bhagwat ◽  
Hariharan Periasamy ◽  
Swapna S. Takalkar ◽  
Rajesh Chavan ◽  
Pavan Tayde ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Lung Infection ◽  
Infection Model ◽  
Phase 3 ◽  
Time Curve ◽  
Unbound Fraction ◽  
Content Type ◽  
Murine Lung ◽  
Selection Of

ABSTRACT Levonadifloxacin is a novel benzoquinolizine subclass of fluoroquinolone, active against quinolone-resistant Staphylococcus aureus. A phase 3 trial for levonadifloxacin and its oral prodrug was recently completed. The present study identified area under the concentration-time curve for the free, unbound fraction of a drug divided by the MIC (fAUC/MIC) as an efficacy determinant for levonadifloxacin in a neutropenic murine lung infection model. Mean plasma fAUC/MIC requirement for static and 1 log10 kill effects against 9 S. aureus were 8.1 ± 6.0 and 25.8 ± 12.3, respectively. These targets were employed in the selection of phase 3 doses.

scholarly journals Improved Oxacillin Treatment Outcomes in Experimental Skin and Lung Infection by a Methicillin-Resistant Staphylococcus aureus Isolate with avraSROperon Deletion

2011 ◽  
Vol 55 (6) ◽  
pp. 2818-2823 ◽  
Author(s):  
Dae Sun Jo ◽  
Christopher P. Montgomery ◽  
Shaohui Yin ◽  
Susan Boyle-Vavra ◽  
Robert S. Daum
Keyword(s):  
Staphylococcus Aureus ◽  
Mutant Strain ◽  
Skin Infection ◽  
Soft Tissues ◽  
Infection Model ◽  
Necrotizing Pneumonia ◽  
Bacterial Burden ◽  
Methicillin Resistant ◽  
Content Type ◽  
Oxacillin Resistance

ABSTRACTMethicillin-resistantStaphylococcus aureus(MRSA) strains are major pathogens causing infections of the skin and soft tissues and more serious, life-threatening diseases, including sepsis and necrotizing pneumonia. ThevraSRoperon encodes the key regulatory system that modulates the stress response ofS. aureuselicited upon exposure to cell wall antibiotics. Mutation ofvraSandvraRresults in decreased oxacillin resistancein vitro. We investigated the effect of oxacillin treatment in experimental models employing a clinical USA300 MRSA strain (strain 923) and an isogenicvraSRdeletion mutant (strain 923-M23). In a murine model ofS. aureusnecrotizing pneumonia, animals were treated with oxacillin, beginning 15 min after inoculation. Among mice infected with mutant strain 923-M23, oxacillin treatment significantly improved survival compared with saline treatment, whereas oxacillin treatment had no effect in mice infected with strain 923. Similarly, treatment with oxacillin decreased the bacterial burden among animals infected with strain 923-M23 but not among animals infected with strain 923. In a murine skin infection model, oxacillin eliminated the development of dermonecrosis among 923-M23-infected mice and decreased the bacterial burden in the lesions, but not among strain 923-infected mice. We conclude that deletion of thevraSRoperon allowed an oxacillin regimen to be effective in murine models of MRSA pneumonia and skin infection. These findings provide proof-of-principle for development of a new antibiotic that could restore the usefulness of oxacillin against MRSA by inhibiting VraS or VraR.

scholarly journals Targeting Surface Protein SasX by Active and Passive Vaccination To Reduce Staphylococcus aureus Colonization and Infection

2015 ◽  
Vol 83 (5) ◽  
pp. 2168-2174 ◽  
Author(s):  
Qian Liu ◽  
Xin Du ◽  
Xufen Hong ◽  
Tianming Li ◽  
Bing Zheng ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Passive Immunization ◽  
Surface Protein ◽  
Lung Infection ◽  
Active Immunization ◽  
Human Neutrophils ◽  
Infection Model ◽  
Nasal Colonization ◽  
Content Type ◽  
Infection Models

SasX is a recently described surface protein ofStaphylococcus aureusthat is linked to the epidemic success of hospital-associated methicillin-resistant clones, in particular in Asia. It enhances nasal colonization and virulence in skin and lung infection models. Here, we evaluated the potential of SasX as a vaccine component in passive and active immunization efforts using mouse infection models. We found that SasX induced a specific immune response predominantly based on IgG1 antibodies. Active immunization with recombinant SasX or passive immunization with rabbit polyclonal anti-SasX IgG significantly decreased the size of lesions caused byS. aureusin a skin infection model. Furthermore, active immunization reduced acute lung injury in a lung infection model. Moreover, active or passive immunization significantly reducedS. aureuscolonization in a nasal colonization model. Finally, anti-SasX IgG enhanced the susceptibility ofS. aureusto killing by human neutrophils. We conclude that SasX is a potential target for therapeutics or vaccines designed to moderate colonization and infection bysasX-positive epidemic strains ofS. aureus.

scholarly journals Cefazolin and Ertapenem, a Synergistic Combination Used To Clear Persistent Staphylococcus aureus Bacteremia

2016 ◽  
Vol 60 (11) ◽  
pp. 6609-6618 ◽  
Author(s):  
George Sakoulas ◽  
Joshua Olson ◽  
Juwon Yim ◽  
Niedita B. Singh ◽  
Monika Kumaraswamy ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Skin Infection ◽  
Disk Diffusion ◽  
Pharmacodynamic Modeling ◽  
Infection Model ◽  
Content Type ◽  
Bloodstream Isolate ◽  
Drug Concentrations

ABSTRACTErtapenem and cefazolin were used in combination to successfully clear refractory methicillin-susceptibleStaphylococcus aureus(MSSA) bacteremia. In addition, recent work has demonstrated activity of combination therapy with beta-lactams from different classes against methicillin-resistantS. aureus(MRSA). The ertapenem-plus-cefazolin combination was evaluated for synergyin vitroandin vivoin a murine skin infection model using an index MSSA bloodstream isolate from a patient in whom persistent bacteremia was cleared with this combination and against a cadre of well-described research strains and clinical strains of MSSA and MRSA. Against the index MSSA bloodstream isolate, ertapenem and cefazolin showed synergy using both checkerboard (fractional inhibitory concentration [FIC] index = 0.375) and time-kill assays. Using a disk diffusion ertapenem potentiation assay, the MSSA isolate showed a cefazolin disk zone increased from 34 to 40 mm.In vitropharmacokinetic/pharmacodynamic modeling at clinically relevant drug concentrations demonstrated bactericidal activity (>3 log10-CFU/ml reduction) of the combination but bacteriostatic activity of ether drug alone at 48 h. A disk diffusion potentiation assay showed that ertapenem increased the cefazolin zone of inhibition by >3 mm for 34/35 (97%) MSSA and 10/15 (67%) MRSA strains. A murine skin infection model of MSSA showed enhanced activity of cefazolin plus ertapenem compared to monotherapy with these agents. After successful use in clearance of MSSA bacteremia, the combination of ertapenem and cefazolin showed synergy against MSSAin vitroandin vivo. This combination may warrant consideration for future clinical study in MSSA bacteremia.

scholarly journals Galectin-3 Is a Target for Proteases Involved in the Virulence of Staphylococcus aureus

2017 ◽  
Vol 85 (7) ◽  
Author(s):  
Jonas Elmwall ◽  
Jakub Kwiecinski ◽  
Manli Na ◽  
Abukar Ahmed Ali ◽  
Veronica Osla ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Skin Infection ◽  
Bacterial Load ◽  
Lesion Size ◽  
Human Neutrophils ◽  
Infection Model ◽  
Content Type ◽  
Immune Evasion Mechanism ◽  
Galectin 3 ◽  
The Impact

ABSTRACT Staphylococcus aureus is a major cause of skin and soft tissue infection. The bacterium expresses four major proteases that are emerging as virulence factors: aureolysin (Aur), V8 protease (SspA), staphopain A (ScpA), and staphopain B (SspB). We hypothesized that human galectin-3, a β-galactoside-binding lectin involved in immune regulation and antimicrobial defense, is a target for these proteases and that proteolysis of galectin-3 is a novel immune evasion mechanism. Indeed, supernatants from laboratory strains and clinical isolates of S. aureus caused galectin-3 degradation. Similar proteolytic capacities were found in Staphylococcus epidermidis isolates but not in Staphylococcus saprophyticus. Galectin-3-induced activation of the neutrophil NADPH oxidase was abrogated by bacterium-derived proteolysis of galectin-3, and SspB was identified as the major protease responsible. The impact of galectin-3 and protease expression on S. aureus virulence was studied in a murine skin infection model. In galectin-3+/+ mice, SspB-expressing S. aureus caused larger lesions and resulted in higher bacterial loads than protease-lacking bacteria. No such difference in bacterial load or lesion size was detected in galectin-3−/− mice, which overall showed smaller lesion sizes than the galectin-3+/+ animals. In conclusion, the staphylococcal protease SspB inactivates galectin-3, abrogating its stimulation of oxygen radical production in human neutrophils and increasing tissue damage during skin infection.

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