scholarly journals Ceftobiprole- and Ceftaroline-Resistant Methicillin-Resistant Staphylococcus aureus

2015 ◽  
Vol 59 (5) ◽  
pp. 2960-2963 ◽  
Author(s):  
Liana C. Chan ◽  
Li Basuino ◽  
Binh Diep ◽  
Stephanie Hamilton ◽  
Som S. Chatterjee ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Methicillin Resistant ◽  
Content Type ◽  
Low Level ◽  
Mrsa Strains ◽  
High Level ◽  
Level Resistance

ABSTRACTThe role ofmecAmutations in conferring resistance to ceftobiprole and ceftaroline, cephalosporins with anti-methicillin-resistantStaphylococcus aureus(MRSA) activity, was determined with MRSA strains COL and SF8300. The SF8300 ceftaroline-passaged mutant carried a singlemecAmutation, E447K (E-to-K change at position 447), and expressed low-level resistance. This mutation in COL conferred high-level resistance to ceftobiprole but only low-level resistance to ceftaroline. The COL ceftaroline-passaged mutant, which expressed high-level resistance to ceftobiprole and ceftaroline, had mutations inpbp2,pbp4, andgdpPbut notmecA.

scholarly journals AUC/MIC Pharmacodynamic Target Is Not a Good Predictor of Vancomycin Efficacy in Methicillin-Resistant Staphylococcus aureus Experimental Endocarditis

2017 ◽  
Vol 61 (6) ◽  
Author(s):  
Ximena Castañeda ◽  
Cristina García-de-la-Mària ◽  
Oriol Gasch ◽  
Juan M. Pericas ◽  
Yolanda Armero ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Good Predictor ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Area Under The Curve ◽  
Methicillin Resistant ◽  
Bacterial Counts ◽  
Content Type ◽  
Treatment Groups ◽  
Mrsa Strains

ABSTRACT The aim of this in vivo study was to compare the efficacy of vancomycin at standard doses (VAN-SD) to that of VAN at adjusted doses (VAN-AD) in achieving a VAN area under the curve/MIC ratio (AUC/MIC) of ≥400 against three methicillin-resistant Staphylococcus aureus (MRSA) strains with different microdilution VAN MICs in an experimental endocarditis model. The valve vegetation bacterial counts after 48 h of VAN therapy were compared, and no differences were observed between the two treatment groups for any of the three strains tested. Overall, for VAN-SD and VAN-AD, the rates of sterile vegetations were 15/45 (33.3%) and 21/49 (42.8%) (P = 0.343), while the medians (interquartile ranges [IQRs]) for log10 CFU/g of vegetation were 2 (0 to 6.9) and 2 (0 to 4.5) (P = 0.384), respectively. In conclusion, this VAN AUC/MIC pharmacodynamic target was not a good predictor of vancomycin efficacy in MRSA experimental endocarditis.

scholarly journals Scope and Predictive Genetic/Phenotypic Signatures of Bicarbonate (NaHCO3) Responsiveness and β-Lactam Sensitization in Methicillin-Resistant Staphylococcus aureus

2020 ◽  
Vol 64 (5) ◽  
Author(s):  
Selvi C. Ersoy ◽  
Mariam Otmishi ◽  
Vanessa T. Milan ◽  
Liang Li ◽  
Youngju Pak ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Clonal Complex ◽  
Population Analysis ◽  
Methicillin Resistant ◽  
Content Type ◽  
Mueller Hinton ◽  
Testing Medium ◽  
Mrsa Strains ◽  
Mueller Hinton Broth

ABSTRACT Addition of sodium bicarbonate (NaHCO3) to standard antimicrobial susceptibility testing medium reveals certain methicillin-resistant Staphylococcus aureus (MRSA) strains to be highly susceptible to β-lactams. We investigated the prevalence of this phenotype (NaHCO3 responsiveness) to two β-lactams among 58 clinical MRSA bloodstream isolates. Of note, ∼75% and ∼36% of isolates displayed the NaHCO3 responsiveness phenotype to cefazolin (CFZ) and oxacillin (OXA), respectively. Neither intrinsic β-lactam MICs in standard Mueller-Hinton broth (MHB) nor population analysis profiles were predictive of this phenotype. Several genotypic markers (clonal complex 8 [CC8]; agr I and spa t008) were associated with NaHCO3 responsiveness for OXA.

scholarly journals Complete Genome Sequences of Eight Methicillin-Resistant Staphylococcus aureus Strains Isolated from Patients in Japan

2019 ◽  
Vol 8 (47) ◽  
Author(s):  
Miyako Hikichi ◽  
Miki Nagao ◽  
Kazunori Murase ◽  
Chihiro Aikawa ◽  
Takashi Nozawa ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Soft Tissue ◽  
Complete Genome ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Clinical Manifestations ◽  
Invasive Disease ◽  
Genome Sequences ◽  
Methicillin Resistant ◽  
Content Type ◽  
Mrsa Strains

Methicillin-resistant Staphylococcus aureus (MRSA) is a major pathogen causing nosocomial infections, and the clinical manifestations of MRSA range from asymptomatic colonization of the nasal mucosa to soft tissue infection to fulminant invasive disease. Here, we report the complete genome sequences of eight MRSA strains isolated from patients in Japan.

scholarly journals Novel Types of Staphylococcal Cassette ChromosomemecElements Identified in Clonal Complex 398 Methicillin-Resistant Staphylococcus aureus Strains

2011 ◽  
Vol 55 (6) ◽  
pp. 3046-3050 ◽  
Author(s):  
Shanshuang Li ◽  
Robert Leo Skov ◽  
Xiao Han ◽  
Anders Rhod Larsen ◽  
Jesper Larsen ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Clonal Complex ◽  
Subtype C ◽  
Methicillin Resistant ◽  
Content Type ◽  
Original Host ◽  
Mrsa Strains ◽  
Type V ◽  
Staphylococcal Cassette Chromosome

ABSTRACTThe structures of staphylococcal cassette chromosomemec(SCCmec) elements carried by 31 clonal complex 398 (CC398) methicillin-resistantStaphylococcus aureus(MRSA) strains isolated from the participants at a conference were analyzed. The SCCmecs were classified into novel types, namely, IX, X, V(5C2&5) subtype c, and IVa. Type V(5C2&5) subtype c, IX, and X SCCmecs carried genes conferring resistance to metals. The structures of SCCmecs from CC398 strains were distinct from those normally found in humans, adding to the evidence that humans are not the original host for CC398.

scholarly journals Chlorhexidine and Mupirocin Susceptibility of Methicillin-Resistant Staphylococcus aureus Isolates in the REDUCE-MRSA Trial

2016 ◽  
Vol 54 (11) ◽  
pp. 2735-2742 ◽  
Author(s):  
Mary K. Hayden ◽  
Karen Lolans ◽  
Katherine Haffenreffer ◽  
Taliser R. Avery ◽  
Ken Kleinman ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Cluster Randomized Trial ◽  
Confidence Limits ◽  
Methicillin Resistant ◽  
Content Type ◽  
Mrsa Infection ◽  
Mupirocin Resistance ◽  
Cluster Randomized ◽  
High Level

Whether targeted or universal decolonization strategies for the control of methicillin-resistant Staphylococcus aureus (MRSA) select for resistance to decolonizing agents is unresolved. The REDUCE-MRSA trial (ClinicalTrials registration no. NCT00980980) provided an opportunity to investigate this question. REDUCE-MRSA was a 3-arm, cluster-randomized trial of either screening and isolation without decolonization, targeted decolonization with chlorhexidine and mupirocin, or universal decolonization without screening to prevent MRSA infection in intensive-care unit (ICU) patients. Isolates from the baseline and intervention periods were collected and tested for susceptibility to chlorhexidine gluconate (CHG) by microtiter dilution; mupirocin susceptibility was tested by Etest. The presence of the qacA or qacB gene was determined by PCR and DNA sequence analysis. A total of 3,173 isolates were analyzed; 2 were nonsusceptible to CHG (MICs, 8 μg/ml), and 5/814 (0.6%) carried qacA or qacB . At baseline, 7.1% of MRSA isolates expressed low-level mupirocin resistance, and 7.5% expressed high-level mupirocin resistance. In a mixed-effects generalized logistic regression model, the odds of mupirocin resistance among clinical MRSA isolates or MRSA isolates acquired in an ICU in intervention versus baseline periods did not differ across arms, although estimates were imprecise due to small numbers. Reduced susceptibility to chlorhexidine and carriage of qacA or qacB were rare among MRSA isolates in the REDUCE-MRSA trial. The odds of mupirocin resistance were no different in the intervention versus baseline periods across arms, but the confidence limits were broad, and the results should be interpreted with caution.

scholarly journals Modulation ofccrABExpression and SCCmecExcision by an Inverted Repeat Element and SarS in Methicillin-Resistant Staphylococcus aureus

2015 ◽  
Vol 59 (10) ◽  
pp. 6223-6232 ◽  
Author(s):  
Shijie Zhang ◽  
Ronghua Ma ◽  
Xiaoyu Liu ◽  
Xu Zhang ◽  
Baolin Sun
Keyword(s):  
Staphylococcus Aureus ◽  
Inverted Repeat ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Regulatory Mechanism ◽  
Human Pathogen ◽  
Entire Family ◽  
Methicillin Resistant ◽  
Content Type ◽  
Mrsa Strains ◽  
Dna Affinity Chromatography

ABSTRACTMethicillin-resistantStaphylococcus aureus(MRSA) is a notorious human pathogen that can cause a broad spectrum of infections. MRSA strains are resistant to almost the entire family of β-lactam antibiotics due to the acquisition of staphylococcal cassette chromosomemec(SCCmec). The chromosome cassette recombinases A and B, encoded byccrABgenes located on SCCmec, play a key role in the excision of SCCmec. Studies have shown thatccrABgenes are expressed in only a minority of cells, suggesting the involvement of a subtle regulatory mechanism inccrABexpression which has not been uncovered. Here, we found that an inverted repeat (IR) element, existing extensively and conservatively within theccrABpromoter of different SCCmectypes, played a repressive role inccrABexpression and SCCmecexcision in MRSA strain N315. Replacement of the IR sequence led to a significant increase inccrABexpression and curing of SCCmecfrom strain N315 cells. In addition, we identified the transcriptional regulator SarS using DNA-affinity chromatography and further demonstrated that SarS can bind to the IR sequence and upregulateccrABexpression and SCCmecexcision. These findings reveal a molecular mechanism regulatingccrABexpression and SCCmecexcision and may provide mechanic insights into the lateral transfer of SCCmecand spread of antibiotic resistance inS. aureus.

scholarly journals Prevalence and molecular characterization of methicillin-resistant Staphylococcus aureus with mupirocin, fusidic acid and/or retapamulin resistance

2020 ◽  
Author(s):  
Wenjing Chen ◽  
Chunyan He ◽  
Han Yang ◽  
Wen Shu ◽  
Zelin Cui ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Fusidic Acid ◽  
Resistance Mechanisms ◽  
Antibiotics Resistance ◽  
Genetic Characteristics ◽  
Methicillin Resistant ◽  
Low Level ◽  
High Level ◽  
Level Resistance

Abstract Data on the prevalence of resistance to mupirocin (MUP), fusidic acid (FA) and retapamulin (RET) in methicillin-resistant Staphylococcus aureus (MRSA) from China are still limited. In this study we examined these three antibiotics resistance pheno and geno-typically in 1206 MRSA clinical isolates. Phenotypic MUP, FA and RET resistance was determined by MICs, and genotypically by PCR and DNA sequencing examining genes mupA / B , fusB - D , cfr and vgaA / Av , and mutations in ileS , fusA / E , rplC , and 23S RNA V domain. The genetic characteristics of resistance isolates were conducted by PFGE and MLST. Overall MRSA MUP, FA and RET resistance was low (5.1%, 1.0% and 0.3%, respectively). The mupA was the mechanism of high-level MUP resistance. All low-level MUP resistance isolates possessed an equivocal mutation N213D in IleS, and 2 of them additionally had the reported V588F mutation impacting the Rossman fold. FusA mutations, such as L461K, H457Q, H457Y and V90I, were the primary FA resistance mechanisms among high-level resistance isolates, most of which contained fusC ; however, all low-level resistance strains carried fusB . No resistance mechanisms detected were found among RET resistance isolates. Genetic analysis demonstrated clone spread for MUP resistance isolates. In conclusion, MUP, FA and RET exhibited highly activity against MRSA isolates. Acquired genes and chromosome-borne genes mutations were responsible for MUP and FA resistance, and further investigation is needed to uncover the RET resistance mechanisms. Moreover, the surveillance to MUP in MRSA should be strengthened to prevent resistance increase due to the expansion of clones.

scholarly journals Telavancin Is Active against Experimental Aortic Valve Endocarditis Caused by Daptomycin- and Methicillin-Resistant Staphylococcus aureus Strains

2016 ◽  
Vol 61 (2) ◽  
Author(s):  
Wessam Abdelhady ◽  
Arnold S. Bayer ◽  
Rachelle Gonzales ◽  
Liang Li ◽  
Yan Q. Xiong
Keyword(s):  
Staphylococcus Aureus ◽  
Aortic Valve ◽  
Untreated Control ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Infection Model ◽  
Methicillin Resistant ◽  
Content Type ◽  
Mrsa Strains ◽  
Culture Negative

ABSTRACT We compared the efficacy of telavancin (TLV) and daptomycin (DAP) in an experimental rabbit endocarditis model caused by two clinically derived daptomycin-resistant (DAPr) methicillin-resistant Staphylococcus aureus (MRSA) strains. TLV treatment significantly reduced MRSA densities in all target tissues and increased the percentage of these organs rendered culture negative compared to those with the untreated control or DAP-treated animals. These results demonstrate that TLV has potent in vivo efficacy against DAPr MRSA isolates in this invasive endovascular infection model.

Vancomycin-gentamicin synergism revisited: effect of gentamicin susceptibility of methicillin-resistant Staphylococcus aureus.

1996 ◽  
Vol 40 (6) ◽  
pp. 1534-1535 ◽  
Author(s):  
L Mulazimoglu ◽  
S D Drenning ◽  
R R Muder
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Staphylococcal Infection ◽  
Bacteriological Response ◽  
Methicillin Resistant ◽  
Gentamicin Resistance ◽  
Agar Dilution ◽  
Mrsa Strains ◽  
High Level ◽  
Time Kill

Vancomycin monotherapy of deep-seated staphylococcal infection may be associated with poor bacteriological response. We evaluated 24 unique patient isolates of methicillin-resistant Staphylococcus aureus (MRSA) for vancomycin-gentamicin synergism by determining time-kill curves for vancomycin at 10 micrograms/ml and gentamicin at 1 microgram/ml. Nine MRSA strains showed high-level gentamicin resistance (HLGR) (MIC, > 500 micrograms/ml), and 15 did not. Vancomycin-gentamicin demonstrated synergism against none of the HLGR strains. For the non-HLGR strains, gentamicin agar dilution MICs ranged from 0.5 to > 128 micrograms/ml. Vancomycin-gentamicin demonstrated synergism against six of these strains and indifference against nine of them. There was no relationship between the agar dilution MIC of gentamicin and the occurrence of synergism against non-HLGR strains. We conclude that a gentamicin MIC of > 500 micrograms/ml predicts a lack of vancomycin-gentamicin synergism for strains of MRSA. For non-HLGR strains, synergism is not predictable from the gentamicin MIC.

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