LTX-109 Is a Novel Agent for Nasal Decolonization of Methicillin-Resistant and -Sensitive Staphylococcus aureus

ABSTRACTNasal decolonization has a proven effect on the prevention of severeStaphylococcus aureusinfections and the control of methicillin-resistantS. aureus(MRSA). However, rising rates of resistance to antibiotics highlight the need for new substances for nasal decolonization. LTX-109 is a broad-spectrum, fast-acting bactericidal antimicrobial drug for topical treatment, which causes membrane disruption and cell lysis. This mechanism of action is not associated with cross-resistance and has a low propensity for development of resistance. In the present study, persistent nasal MRSA and methicillin-sensitiveS. aureus(MSSA) carriers were treated for 3 days with vehicle or with 1%, 2%, or 5% LTX-109. A significant effect on nasal decolonization was observed already after 2 days of LTX-109 treatment in subjects treated with 2% or 5% LTX-109 compared to vehicle (P≤ 0.0012 by Dunnett′s test). No safety issues were noted during the 9-week follow-up period. Minimal reversible epithelial lesions were observed in the nasal cavity. The systemic exposure was very low, with a maximum concentration of drug in plasma (Cmax) at 1 to 2 h postdosing (3.72 to 11.7 ng/ml). One week after treatment initiation, LTX-109 was not detectable in any subject. Intranasal treatment ofS. aureuswith LTX-109 is safe and reduces the bacterial load already after a single day of treatment. Hence, LTX-109 has potential as a new and effective antimicrobial agent with a low propensity of resistance development that can prevent infections by MSSA/MRSA during hospitalization. (This study has been registered atClinicalTrials.govunder registration no. NCT01158235.)

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Daptomycin plus Fosfomycin, a Synergistic Combination in Experimental Implant-Associated Osteomyelitis Due to Methicillin-Resistant Staphylococcus aureus in Rats

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.04246-14 ◽

2014 ◽

Vol 59 (2) ◽

pp. 859-863 ◽

Cited By ~ 9

Author(s):

Tilman Lingscheid ◽

Wolfgang Poeppl ◽

Dominik Bernitzky ◽

Luzia Veletzky ◽

Manuel Kussmann ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Once Daily ◽

Methicillin Resistant ◽

Bacterial Counts ◽

Content Type ◽

Bacterial Cultures ◽

Development Of Resistance ◽

Bacterial Inoculum ◽

Titanium Wire ◽

Mrsa Infection

ABSTRACTThe aim of this study was to evaluate the combination of daptomycin and fosfomycin in experimental chronic implant-associated osteomyelitis due to methicillin-resistantStaphylococcus aureus(MRSA). Infection was induced in the tibiae of rats by the insertion of a bacterial inoculum (1 to 5 × 108CFU/ml) of a clinical MRSA isolate and a titanium wire. Four weeks after infection, each animal was assigned to a treatment group: daptomycin monotherapy at 60 mg/kg of body weight once daily (n= 10), fosfomycin monotherapy at 40 mg/kg once daily (n= 10), or daptomycin and fosfomycin combined at 60 mg/kg and 40 mg/kg, respectively, once daily (n= 9). Ten animals were left untreated. After a 3-week treatment period, the animals were euthanized, and the infected tibiae and implants were processed for quantitative bacterial cultures. The bacterial cultures from bones were positive for MRSA in all animals in the untreated group, the daptomycin group, and the fosfomycin group, with median bacterial counts of 2.34 × 106CFU/g bone, 1.57 × 106CFU/g bone, and 3.48 × 102CFU/g bone, respectively. In the daptomycin-fosfomycin group, 6 out of 9 animals were positive for MRSA, with a median count of 7.92 CFU/g bone. Bacterial cultures derived from the titanium wires were negative in the fosfomycin- and daptomycin-fosfomycin-treated groups. Based on bacterial counts in bones, treatment with daptomycin-fosfomycin was statistically significantly superior to all that of the other groups (P≤ 0.003). Fosfomycin was superior to daptomycin and no treatment (P< 0.0001). No development of resistance was observed in any treatment arm. The combination of daptomycin and fosfomycin demonstrated synergism against MRSA in experimental implant-associated osteomyelitis.

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Participation of CD11c+Leukocytes in Methicillin-Resistant Staphylococcus aureus Clearance from the Lung

Infection and Immunity ◽

10.1128/iai.01299-10 ◽

2011 ◽

Vol 79 (5) ◽

pp. 1898-1904 ◽

Cited By ~ 31

Author(s):

Francis J. Martin ◽

Dane Parker ◽

Bryan S. Harfenist ◽

Grace Soong ◽

Alice Prince

Keyword(s):

Staphylococcus Aureus ◽

Pulmonary Infection ◽

Fluorescent Protein ◽

Pulmonary Inflammation ◽

Bacterial Load ◽

Airway Epithelial Cells ◽

High Morbidity ◽

Proinflammatory Response ◽

Methicillin Resistant ◽

Content Type

ABSTRACTStaphylococcus aureuscauses especially severe pulmonary infection, associated with high morbidity and mortality. In addition to the effects of specific virulence factors, it appears that the intensity of the host proinflammatory response, particularly in the initial stages of infection, contributes substantially to pulmonary damage. We tested the hypothesis that the CD11c+leukocytes are important in the host response to pulmonary infection with methicillin-resistantS. aureus(MRSA) USA300. Clodronate-induced depletion of the alveolar macrophage population resulted in increased numbers of dendritic cells (DCs) and CD4+cells in bronchoalveolar lavage (BAL) fluid and was associated with significantly increased mortality by 18 h followingS. aureusinoculation but had no effect on bacterial load or polymorphonuclear leukocyte (PMN) numbers in the lung. These clodronate-treated mice also had increased expression of interleukin-17A/F (IL-17A/F) and CXCL10 but not of gamma interferon (IFN-γ) or tumor necrosis factor (TNF). Depletion of the dendritic cell population in mice expressing a CD11c-enhanced green fluorescent protein (EGFP)-diphtheria toxin receptor (DTR) transgene was associated with an increased bacterial load in the lung but not increased mortality. Both DCs and airway epithelial cells produced CXCL9, -10, and -11 in response toS. aureus. Pretreatment of mice with an anti-CXCR3 antibody prior to inoculation with MRSA substantially reduced CD4+cells and decreased pulmonary inflammation at 18 h postinfection compared to pretreatment with an IgG control. The results of these experiments suggest that CD11c+cells, the induction of CXCR3 ligand expression, and subsequent CD4+cell recruitment have an important role in the pathogenesis of severe MRSA pulmonary infection.

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Heterogeneity ofmprFSequences in Methicillin-Resistant Staphylococcus aureus Clinical Isolates: Role in Cross-Resistance between Daptomycin and Host Defense Antimicrobial Peptides

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.03422-14 ◽

2014 ◽

Vol 58 (12) ◽

pp. 7462-7467 ◽

Cited By ~ 38

Author(s):

Arnold S. Bayer ◽

Nagendra N. Mishra ◽

George Sakoulas ◽

Poochit Nonejuie ◽

Cynthia C. Nast ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Host Defense ◽

Hot Spot ◽

Cross Resistance ◽

Phospholipid Content ◽

Nucleotide Polymorphisms ◽

Gain Of Function ◽

Host Defense Peptides ◽

Methicillin Resistant ◽

Content Type

ABSTRACTOver the past several years, single-nucleotide polymorphisms (SNPs) within themprFopen reading frame (ORF) have been proposed to be associated with a gain-of-function phenotype in terms of daptomycin (DAP) nonsusceptibility (referred to as daptomycin resistance [DAP-R] herein for ease of presentation) inStaphylococcus aureus. We investigated the frequencies of SNPs within themprFORF and the relationships of such SNPs to cross-resistance between DAP and cationic host defense peptides (HDPs). Thirty-five well-characterized, unique DAP-susceptible (DAP-S) and DAP-R methicillin-resistantS. aureus(MRSA) isolates of the clonal complex 5 genotype were used. In addition tomprFSNPs and DAP-HDP cross-resistance, several other key genotypic and phenotypic metrics often associated with DAP-R were delineated, as follows: (i)mprFexpression, (ii) membrane phospholipid content, (iii) positive surface charge, (iv) DAP binding, and (v) cell wall thickness profiles. A number of DAP-S strains (MICs of ≤1 μg/ml) exhibitedmprFSNPs, occasionally with high-levelmprFsequence variation from the genotype reference strain. However, none of these SNPs were localized to well-chronicledmprFhot spot locations associated with DAP-R inS. aureus. In contrast, all 8 DAP-R isolates demonstrated SNPs within such knownmprFhot spots. Moreover, only the DAP-R strains showed MprF gain-of-function phenotypes, enhancedmprFexpression, higher survival against two prototypical HDPs, and reduced DAP binding. Although a heterogenous array ofmprFSNPs were often found in DAP-S strains, only selected hot spot SNPs, combined with concurrentmprFdysregulation, were associated with the DAP-R phenotype.

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Role of Daptomycin on Burn Wound Healing in an Animal Methicillin-Resistant Staphylococcus aureus Infection Model

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00606-17 ◽

2017 ◽

Vol 61 (9) ◽

Cited By ~ 15

Author(s):

Oriana Simonetti ◽

Guendalina Lucarini ◽

Fiorenza Orlando ◽

Elisa Pierpaoli ◽

Roberto Ghiselli ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Wound Healing ◽

Growth Factor ◽

Bacterial Load ◽

Histological Evaluation ◽

Control Group ◽

Burn Wound ◽

Burn Scar ◽

Methicillin Resistant ◽

Content Type

ABSTRACT Prolonged hospitalization and antibiotic therapy are risk factors for the development of methicillin-resistant Staphylococcus aureus (MRSA) infections in thermal burn patients. We used a rat model to study the in vivo efficacy of daptomycin in the treatment of burn wound infections by S. aureus, and we evaluated the wound healing process through morphological and immunohistochemical analysis. A copper bar heated in boiling water was applied on a paraspinal site of each rat, resulting in two full-thickness burns. A small gauze was placed over each burn and inoculated with 5 × 107 CFU of S. aureus ATCC 43300. The study included two uninfected control groups with and without daptomycin treatment, an infected control group that did not receive any treatment, and two infected groups treated, respectively, with intraperitoneal daptomycin and teicoplanin. The main outcome measures were quantitative culture, histological evaluation of tissue repair, and immunohistochemical expression of wound healing markers: epidermal growth factor receptor (EGFR) and fibroblast growth factor 2 (FGF-2). The highest inhibition of infection was achieved in the group that received daptomycin, which reduced the bacterial load from 107 CFU/ml to about 103 CFU/g (P < 0.01). The groups treated with daptomycin showed better overall healing with epithelialization and significantly higher collagen scores than the other groups, and these findings were also confirmed by immunohistochemical data. In conclusion, our results support the hypothesis that daptomycin is an important modulator of wound repair by possibly reducing hypertrophic burn scar formation.

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Efficacy of Novel Antistaphylococcal Ectolysin P128 in a Rat Model of Methicillin-Resistant Staphylococcus aureus Bacteremia

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01358-17 ◽

2017 ◽

Vol 62 (2) ◽

Cited By ~ 8

Author(s):

Shankaramurthy Channabasappa ◽

Murali Durgaiah ◽

Ravisha Chikkamadaiah ◽

Senthil Kumar ◽

Amruta Joshi ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Bactericidal Activity ◽

Rat Model ◽

Bacterial Load ◽

High Morbidity ◽

Bolus Administration ◽

Methicillin Resistant ◽

Content Type ◽

Systemic Infections ◽

Novel Therapeutic

ABSTRACTStaphylococcus aureuscauses systemic infections with high morbidity and mortality, and the emergence of drug-resistant strains is a rapidly growing clinical concern. Novel therapeutic agents are required to tackleS. aureusinfections. P128 is a bacteriophage-derived chimeric ectolysin with potent and rapid bactericidal activity againstS. aureus. In the present study, the efficacy of P128 was evaluated in a newly developed rat model ofS. aureusbacteremia. Prior toin vivotesting, P128 was shown to be stable in whole blood by incubation in rat blood for up to 6 h and testing its bactericidal activity against the methicillin-resistantS. aureusisolate USA300. Rats succumbed to intravenous challenge with 109CFU ofS. aureusUSA300, resulting in 80 to 100% mortality by day 14. Evaluation of the bacterial load in various organs at 96 h postinfection revealed high bacterial counts in the kidney, and this correlated with the presence of renal abscesses. Treatment of infected animals with P128 either by intravenous bolus administration via tail vein or by 1-h infusion via the jugular vein at 2 h postinfection resulted in the dose-dependent survival of rats. P128 treatment also resulted in very few or no abscesses in the kidneys. These data show that P128 is stable in the physiological milieu and that intravenous treatment with P128 is highly effective in rescuing rats fromS. aureusbacteremia. P128 can be a novel therapeutic option for treatment ofS. aureussystemic infections.

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Impact of Exposure of Methicillin-Resistant Staphylococcus aureus to Polyhexanide In Vitro and In Vivo

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00272-17 ◽

2017 ◽

Vol 61 (10) ◽

Cited By ~ 10

Author(s):

A. Renzoni ◽

E. Von Dach ◽

C. Landelle ◽

S. M. Diene ◽

C. Manzano ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Bacterial Resistance ◽

Broth Culture ◽

Cross Resistance ◽

Methicillin Resistant ◽

Content Type ◽

Genomic Changes ◽

Low Concentrations

ABSTRACT Methicillin-resistant Staphylococcus aureus (MRSA) resistant to decolonization agents such as mupirocin and chlorhexidine increases the need for development of alternative decolonization molecules. The absence of reported severe adverse reactions and bacterial resistance to polyhexanide makes it an excellent choice as a topical antiseptic. In the present study, we evaluated the in vitro and in vivo capacity to generate strains with reduced polyhexanide susceptibility and cross-resistance with chlorhexidine and/or antibiotics currently used in clinic. Here we report the in vitro emergence of reduced susceptibility to polyhexanide by prolonged stepwise exposure to low concentrations in broth culture. Reduced susceptibility to polyhexanide was associated with genomic changes in the mprF and purR genes and with concomitant decreased susceptibility to daptomycin and other cell wall-active antibiotics. However, the in vitro emergence of reduced susceptibility to polyhexanide did not result in cross-resistance to chlorhexidine. During in vivo polyhexanide clinical decolonization treatment, neither reduced polyhexanide susceptibility nor chlorhexidine cross-resistance was observed. Together, these observations suggest that polyhexanide could be used safely for decolonization of carriers of chlorhexidine-resistant S. aureus strains; they also highlight the need for careful use of polyhexanide at low antiseptic concentrations.

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No Decrease in Susceptibility to NVC-422 in Multiple-Passage Studies with Methicillin-Resistant Staphylococcus aureus, S. aureus, Pseudomonas aeruginosa, and Escherichia coli

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.05985-11 ◽

2012 ◽

Vol 56 (5) ◽

pp. 2753-2755 ◽

Cited By ~ 13

Author(s):

Louisa D'Lima ◽

Lisa Friedman ◽

Lu Wang ◽

Ping Xu ◽

Mark Anderson ◽

...

Keyword(s):

Escherichia Coli ◽

Staphylococcus Aureus ◽

Pseudomonas Aeruginosa ◽

Fusidic Acid ◽

Methicillin Resistant Staphylococcus Aureus ◽

Cross Resistance ◽

Methicillin Resistant ◽

Content Type ◽

E Coli ◽

Resistant Strains

ABSTRACTTwenty-five serial passages ofEscherichia coli,Pseudomonas aeruginosa, andStaphylococcus aureusand 50 passages of methicillin-resistantStaphylococcus aureusresulted in no significant increase in NVC-422 MICs, while ciprofloxacin MICs increased 256-fold forE. coliand 32-fold forP. aeruginosaandS. aureus. Mupirocin, fusidic acid, and retapamulin MICs for MRSA increased 64-, 256-, and 16-fold, respectively. No cross-resistance to NVC-422 was observed with mupirocin-, fusidic acid-, and retapamulin-resistant strains.

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Association of mprF mutations with cross-resistance to daptomycin and vancomycin in methicillin-resistant Staphylococcus aureus (MRSA)

Scientific Reports ◽

10.1038/s41598-020-73108-x ◽

2020 ◽

Vol 10 (1) ◽

Cited By ~ 3

Author(s):

Kanate Thitiananpakorn ◽

Yoshifumi Aiba ◽

Xin-Ee Tan ◽

Shinya Watanabe ◽

Kotaro Kiga ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Cross Resistance ◽

Surface Charges ◽

Genetic Determinants ◽

Methicillin Resistant ◽

Bacterial Surface ◽

The Cross ◽

Altered Gene ◽

The Impact

Abstract We first reported a phenomenon of cross-resistance to vancomycin (VCM) and daptomycin (DAP) in methicillin-resistant Staphylococcus aureus (MRSA) in 2006, but mechanisms underlying the cross-resistance remain incompletely understood. Here, we present a follow-up study aimed to investigate genetic determinants associated with the cross-resistance. Using 12 sets of paired DAP susceptible (DAPS) and DAP non-susceptible (DAPR) MRSA isolates from 12 patients who had DAP therapy, we (i) assessed susceptibility to DAP and VCM, (ii) compared whole-genome sequences, (iii) identified mutations associated with cross-resistance to DAP and VCM, and (iv) investigated the impact of altered gene expression and metabolic pathway relevant to the cross-resistance. We found that all 12 DAPR strains exhibiting cross-resistance to DAP and VCM carried mutations in mprF, while one DAPR strain with reduced susceptibility to only DAP carried a lacF mutation. On the other hand, among the 32 vancomycin-intermediate S. aureus (VISA) strains isolated from patients treated with VCM, five out of the 18 strains showing cross-resistance to DAP and VCM carried a mprF mutation, while 14 strains resistant to only VCM had no mprF mutation. Moreover, substitution of mprF in a DAPS strain with mutated mprF resulted in cross-resistance and vice versa. The elevated lysyl-phosphatidylglycerol (L-PG) production, increased positive bacterial surface charges and activated cell wall (CW) synthetic pathways were commonly found in both clinical isolates and laboratory-developed mutants that carry mprF mutations. We conclude that mprF mutation is responsible for the cross-resistance of MRSA to DAP and VCM, and treatment with DAP is more likely to select for mprF-mediated cross-resistance than is with VCM.

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Frequency and Distribution of Single-Nucleotide Polymorphisms withinmprFin Methicillin-Resistant Staphylococcus aureus Clinical Isolates and Their Role in Cross-Resistance to Daptomycin and Host Defense Antimicrobial Peptides

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00970-15 ◽

2015 ◽

Vol 59 (8) ◽

pp. 4930-4937 ◽

Cited By ~ 46

Author(s):

Arnold S. Bayer ◽

Nagendra N. Mishra ◽

Liang Chen ◽

Barry N. Kreiswirth ◽

Aileen Rubio ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Single Nucleotide Polymorphisms ◽

Surface Charge ◽

Host Defense ◽

Cross Resistance ◽

Nucleotide Polymorphisms ◽

Single Nucleotide ◽

Methicillin Resistant ◽

Content Type ◽

Positive Surface Charge

ABSTRACTMprF is responsible for the lysinylation of phosphatidylglycerol (PG) to synthesize the positively charged phospholipid (PL) species, lysyl-PG (L-PG). It has been proposed that the single-nucleotide polymorphisms (SNPs) within themprFopen reading frame (ORF) are associated with a gain-in-function phenotype in terms of daptomycin resistance inStaphylococcus aureus. (Note that although the official term is daptomycin nonsusceptibility, we use the term daptomycin resistance in this paper for ease of presentation.) Using 22 daptomycin-susceptible (DAPs)/daptomycin-resistant (DAPr) clinical methicillin-resistantS. aureus(MRSA) strain pairs, we assessed (i) the frequencies and distribution of putativemprFgain-in-function SNPs, (ii) the relationships of the SNPs to both daptomycin resistance and cross-resistance to the prototypical endovascular host defense peptide (HDP) thrombin-induced platelet microbicidal protein (tPMP), and (iii) the impact ofmprFSNPs on positive surface charge phenotype and modifications of membrane PL profiles. Most of themprFSNPs identified in our DAPrstrains were clustered within the two MprF loci, (i) the central bifunctional domain and (ii) the C-terminal synthase domain. Moreover, we were able to correlate the presence and location ofmprFSNPs in DAPrstrains with HDP cross-resistance, positive surface charge, and L-PG profiles. Although DAPrstrains withmprFSNPs in the bifunctional domain showed higher resistance to tPMPs than DAPrstrains with SNPs in the synthase domain, this relationship was not observed in positive surface charge assays. These results demonstrated that both charge-mediated and -unrelated mechanisms are involved in DAP resistance and HDP cross-resistance inS. aureus.

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Evaluation of Ceftaroline Activity against Heteroresistant Vancomycin-Intermediate Staphylococcus aureus and Vancomycin-Intermediate Methicillin-Resistant S. aureus Strains in anIn VitroPharmacokinetic/Pharmacodynamic Model: Exploring the “Seesaw Effect”

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02308-12 ◽

2013 ◽

Vol 57 (6) ◽

pp. 2664-2668 ◽

Cited By ~ 37

Author(s):

Brian J. Werth ◽

Molly E. Steed ◽

Glenn W. Kaatz ◽

Michael J. Rybak

Keyword(s):

Staphylococcus Aureus ◽

Pharmacokinetic Parameters ◽

Bacterial Killing ◽

Methicillin Resistant ◽

Content Type ◽

Penicillin Binding Proteins ◽

Development Of Resistance ◽

Mutant Strains ◽

Mrsa Strains

ABSTRACTA “seesaw effect” in methicillin-resistantStaphylococcus aureus(MRSA) has been demonstrated, whereby susceptibility to β-lactam antimicrobials increases as glyco- and lipopeptide susceptibility decreases. We investigated this effect by evaluating the activity of the anti-MRSA cephalosporin ceftaroline against isogenic pairs of MRSA strains with various susceptibilities to vancomycin in anin vitropharmacokinetic/pharmacodynamic (PK/PD) model. The activities of ceftaroline at 600 mg every 12 h (q12h) (targeted free maximum concentration of drug in serum [fCmax], 15.2 μg/ml; half-life [t1/2], 2.3 h) and vancomycin at 1 g q12h (targetedfCmax, 18 μg/ml;t1/2, 6 h) were evaluated against 3 pairs of isogenic clinical strains of MRSA that developed increased MICs to vancomycin in patients while on therapy using a two-compartment hollow-fiber PK/PD model with a starting inoculum of ∼107CFU/ml over a 96-h period. Bacterial killing and development of resistance were evaluated. Expression of penicillin-binding proteins (PBPs) 2 and 4 was evaluated by reverse transcription (RT)-PCR. The achieved pharmacokinetic parameters were 98 to 119% of the targeted values. Ceftaroline and vancomycin were bactericidal against 5/6 and 1/6 strains, respectively, at 96 h. Ceftaroline was more active against the mutant strains than the parent strains, with this difference being statistically significant for 2/3 strain pairs at 96 h. The level of PBP2 expression was 4.4× higher in the vancomycin-intermediateS. aureus(VISA) strain in 1/3 pairs. The levels of PBP2 and PBP4 expression were otherwise similar between the parent and mutant strains. These data support the seesaw hypothesis that ceftaroline, like traditional β-lactams, is more active against strains that are less susceptible to vancomycin even when the ceftaroline MICs are identical. Further research to explore these unique findings is warranted.

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