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

2014 ◽  
Vol 58 (12) ◽  
pp. 7462-7467 ◽  
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.

scholarly journals 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

2015 ◽  
Vol 59 (8) ◽  
pp. 4930-4937 ◽  
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.

scholarly journals Nonredundant Roles of Interleukin-17A (IL-17A) and IL-22 in Murine Host Defense against Cutaneous and Hematogenous Infection Due to Methicillin-Resistant Staphylococcus aureus

2015 ◽  
Vol 83 (11) ◽  
pp. 4427-4437 ◽  
Author(s):  
Liana C. Chan ◽  
Siyang Chaili ◽  
Scott G. Filler ◽  
Kevin Barr ◽  
Huiyuan Wang ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
T Cell ◽  
Host Defense ◽  
Neutralizing Antibodies ◽  
Neutrophil Infiltration ◽  
Renal Tissue ◽  
Methicillin Resistant ◽  
Content Type ◽  
Interleukin 17A ◽  
Mrsa Infection

ABSTRACTStaphylococcus aureusis the leading cause of skin and skin structure infections (SSSI) in humans. Moreover, the high frequency of recurring SSSI due toS. aureus, particularly methicillin-resistantS. aureus(MRSA) strains, suggests that infection induces suboptimal anamnestic defenses. The present study addresses the hypothesis that interleukin-17A (IL-17A) and IL-22 play distinct roles in immunity to cutaneous and invasive MRSA infection in a mouse model of SSSI. Mice were treated with specific neutralizing antibodies against IL-17A and/or IL-22 and infected with MRSA, after which the severity of infection and host immune response were determined. Neutralization of either IL-17A or IL-22 reduced T cell and neutrophil infiltration and host defense peptide elaboration in lesions. These events corresponded with increased abscess severity, MRSA viability, and CFU density in skin. Interestingly, combined inhibition of IL-17A and IL-22 did not worsen abscesses but did increase gamma interferon (IFN-γ) expression at these sites. The inhibition of IL-22 led to a reduction in IL-17A expression, but not vice versa. These results suggest that the expression of IL-17A is at least partially dependent on IL-22 in this model. Inhibition of IL-17A but not IL-22 led to hematogenous dissemination to kidneys, which correlated with decreased T cell infiltration in renal tissue. Collectively, these findings indicate that IL-17A and IL-22 have complementary but nonredundant roles in host defense against cutaneous versus hematogenous infection. These insights may support targeted immune enhancement or other novel approaches to address the challenge of MRSA infection.

scholarly journals Innate Immune Memory Contributes to Host Defense against Recurrent Skin and Skin Structure Infections Caused by Methicillin-Resistant Staphylococcus aureus

2016 ◽  
Vol 85 (2) ◽  
Author(s):  
Liana C. Chan ◽  
Siyang Chaili ◽  
Scott G. Filler ◽  
Lloyd S. Miller ◽  
Norma V. Solis ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Host Defense ◽  
Protective Efficacy ◽  
Innate Immune ◽  
Immune Memory ◽  
Wild Type ◽  
Methicillin Resistant ◽  
Content Type ◽  
Skin Structure ◽  
Mrsa Infection

ABSTRACT Staphylococcus aureus is the leading cause of skin and skin structure infections (SSSI). The high frequency of recurring SSSI due to S. aureus, including methicillin-resistant S. aureus (MRSA) strains, despite high titers of specific antibodies and circulating T cells, implies that traditional adaptive immunity imparts incomplete protection. We hypothesized that innate immune memory contributes to the protective host defense against recurring MRSA infection. To test this hypothesis, SSSI was induced in wild-type and rag1 −/− mice in the BALB/c and C57BL/6 backgrounds. Prior infection (priming) of wild-type and rag1 −/− mice of either background afforded protection against repeat infection, as evidenced by reduced abscess severities and decreased CFU densities compared to those in naive controls. Interestingly, protection was greater on the previously infected flank than on the naive flank for wild-type and rag1 −/− mice. For wild-type mice, protective efficacy corresponded to increased infiltration of neutrophils (polymorphonuclear leukocytes [PMN]), macrophages (MΦ), Langerin+ dendritic cells (LDC), and natural killer (NK) cells. Protection was associated with the induction of interleukin-17A (IL-17A), IL-22, and gamma interferon (IFN-γ) as well as the antimicrobial peptides CRAMP and mβD-3. Priming also protected rag1 −/− mice against recurring SSSI, with increased MΦ and LDC infiltration and induction of IL-22, CRAMP, and mβD-3. These findings suggest that innate immune memory, mediated by specific cellular and molecular programs, likely contributes to the localized host defense in recurrent MRSA SSSI. These insights support the development of targeted immunotherapeutic strategies to address the challenge of MRSA infection.

scholarly journals Impact of the Novel Prophage ϕSA169 on Persistent Methicillin-Resistant Staphylococcus aureus Endovascular Infection

mSystems ◽  
2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Liang Li ◽  
Genzhu Wang ◽  
Yi Li ◽  
Patrice Francois ◽  
Arnold S. Bayer ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Hot Spot ◽  
Critical Role ◽  
Bacteriophage Therapy ◽  
Methicillin Resistant ◽  
Content Type ◽  
Antimicrobial Resistance Genes

ABSTRACT Persistent methicillin-resistant Staphylococcus aureus (MRSA) endovascular infections are life-threatening syndromes with few therapeutic options. The potential impact of bacteriophages on the persistent outcome has not been well studied. In this study, we investigated the role of a novel prophage (ϕSA169) in MRSA persistence by using a lysogen-free clinically resolving bacteremia (RB) isolate and comparing it to a derivative which was obtained by infecting the RB strain with ϕSA169, which has been lysogenized in a clinical persistent MRSA bacteremia (PB) isolate. Similar to the PB isolate, the ϕSA169-lysogenized RB strain exhibited well-defined in vitro and in vivo phenotypic and genotypic signatures related to the persistent outcome, including earlier activation of global regulators (i.e., sigB, sarA, agr RNAIII, and sae); higher expression of a critical purine biosynthesis gene, purF; and higher growth rates accompanied by lower ATP levels and vancomycin (VAN) susceptibility and stronger δ-hemolysin and biofilm formation versus its isogenic parental RB isolate. Notably, the contribution of ϕSA169 in persistent outcome with VAN treatment was confirmed in an experimental infective endocarditis model. Taken together, these results indicate the critical role of the prophage ϕSA169 in persistent MRSA endovascular infections. Further studies are needed to identify the mechanisms of ϕSA169 in mediating the persistence, as well as establishing the scope of impact, of this prophage in other PB strains. IMPORTANCE Bacteriophages are viruses that invade the bacterial host, disrupt bacterial metabolism, and cause the bacterium to lyse. Because of its remarkable antibacterial activity and unique advantages over antibiotics, for instance, bacteriophage is specific for one species of bacteria and resistance to phage is less common than resistance to antibiotics. Indeed, bacteriophage therapy for treating infections due to multidrug-resistant pathogens in humans has become a research hot spot. However, it is also worth considering that bacteriophages are transferable and could cotransfer host chromosomal genes, e.g., virulence and antimicrobial resistance genes, while lysogenizing and integrating into the bacterial chromosome (prophage), thus playing a role in bacterial evolution and virulence. In the current study, we identified a novel prophage, ϕSA169, from a clinical persistent MRSA bacteremia isolate, and we determined that ϕSA169 mediated well-defined in vitro and in vivo phenotypic and genotypic signatures related to the persistent outcome, which may represent a unique and important persistent mechanism(s).

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

2017 ◽  
Vol 61 (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.

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

2012 ◽  
Vol 56 (5) ◽  
pp. 2753-2755 ◽  
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.

scholarly journals Evolution and Single-Nucleotide Polymorphisms in Methicillin-Resistant Staphylococcus aureus Strains with Reduced Susceptibility to Vancomycin and Daptomycin, Based on Determination of the Complete Genome

2015 ◽  
Vol 59 (6) ◽  
pp. 3585-3587 ◽  
Author(s):  
Tetsuo Yamaguchi ◽  
Shingo Suzuki ◽  
Sakiko Okamura ◽  
Yuri Miura ◽  
Ayaka Tsukimori ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Single Nucleotide Polymorphisms ◽  
Complete Genome ◽  
Nucleotide Polymorphisms ◽  
Single Nucleotide ◽  
Methicillin Resistant ◽  
Content Type ◽  
Rifampin Resistance ◽  
Generation Sequencing

ABSTRACTWe obtained a series of methicillin-resistantStaphylococcus aureusisolates, including both daptomycin-susceptible strain TD1 and daptomycin-resistant strain TD4, from a patient. We determined the complete genome sequences of TD1 and TD4 using next-generation sequencing, and only four single-nucleotide polymorphisms (SNPs) were identified, one each incapB(E58K),rpoB(H481Y),lytN(I16V), andmprF(V351E). We determined that these four SNPs were sufficient to cause the strains to develop daptomycin, vancomycin, and rifampin resistance.

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

2014 ◽  
Vol 59 (1) ◽  
pp. 145-151 ◽  
Author(s):  
Anna C. Nilsson ◽  
Håkan Janson ◽  
Hedda Wold ◽  
Anders Fugelli ◽  
Karin Andersson ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Bacterial Load ◽  
Systemic Exposure ◽  
Cross Resistance ◽  
Methicillin Resistant ◽  
Content Type ◽  
Safety Issues ◽  
Development Of Resistance ◽  
Epithelial Lesions

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.)

scholarly journals The GraS Sensor in Staphylococcus aureus Mediates Resistance to Host Defense Peptides Differing in Mechanisms of Action

2015 ◽  
Vol 84 (2) ◽  
pp. 459-466 ◽  
Author(s):  
Siyang Chaili ◽  
Ambrose L. Cheung ◽  
Arnold S. Bayer ◽  
Yan Q. Xiong ◽  
Alan J. Waring ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Host Defense ◽  
Regulatory System ◽  
Annexin V ◽  
Host Defense Peptides ◽  
Content Type ◽  
Protease Activation ◽  
Defense Peptides ◽  
Sense And Respond ◽  
Assay Conditions

Staphylococcus aureususes the two-component regulatory system GraRS to sense and respond to host defense peptides (HDPs). However, the mechanistic impact of GraS or its extracellular sensing loop (EL) on HDP resistance is essentially unexplored. Strains with null mutations in the GraS holoprotein (ΔgraS) or its EL (ΔEL) were compared for mechanisms of resistance to HDPs of relevant immune sources: neutrophil α-defensin (human neutrophil peptide 1 [hNP-1]), cutaneous β-defensin (human β-defensin 2 [hBD-2]), or the platelet kinocidin congener RP-1. Actions studied by flow cytometry included energetics (ENR); membrane permeabilization (PRM); annexin V binding (ANX), and cell death protease activation (CDP). Assay conditions simulated bloodstream (pH 7.5) or phagolysosomal (pH 5.5) pH contexts.S. aureusstrains were more susceptible to HDPs at pH 7.5 than at pH 5.5, and each HDP exerted a distinct effect signature. The impacts of ΔgraSand ΔΕL on HDP resistance were peptide and pH dependent. Both mutants exhibited defects in ANX response to hNP-1 or hBD-2 at pH 7.5, but only hNP-1 did so at pH 5.5. Both mutants exhibited hyper-PRM, -ANX, and -CDP responses to RP-1 at both pHs and hypo-ENR at pH 5.5. The actions correlated with ΔgraSor ΔΕL hypersusceptibility to hNP-1 or RP-1 (but not hBD-2) at pH 7.5 and to all study HDPs at pH 5.5. An exogenous EL mimic protected mutant strains from hNP-1 and hBD-2 but not RP-1, indicating that GraS and its EL play nonredundant roles inS. aureussurvival responses to specific HDPs. These findings suggest that GraS mediates specific resistance countermeasures to HDPs in immune contexts that are highly relevant toS. aureuspathogenesis in humans.

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