scholarly journals Comparison of Adhesion and Virulence of Two Predominant Hospital-Acquired Methicillin-Resistant Staphylococcus aureus Clones and Clonal Methicillin-Susceptible S. aureus Isolates

2008 ◽  
Vol 76 (11) ◽  
pp. 5133-5138 ◽  
Author(s):  
Hatice Karauzum ◽  
Tristan Ferry ◽  
Sophie de Bentzmann ◽  
Gérard Lina ◽  
Michèle Bes ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Airway Epithelial Cells ◽  
Sequence Type ◽  
Airway Epithelial ◽  
Methicillin Resistant ◽  
Type Iv ◽  
In Vitro Adhesion ◽  
A Minor ◽  
Hospital Acquired

ABSTRACT The virulence of SCCmec type IV hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates belonging to the major sequence type 8 (ST8 [Lyon clone]) and to a minor upcoming clone, ST5, was compared with that of methicillin-susceptible S. aureus (MSSA) isolates of matching sequence types. In vitro adhesion to human airway epithelial cells (HAECs) as an indicator of dissemination and mortality in a murine sepsis model as an indicator of virulence were evaluated. Ten MRSA isolates and 8 MSSA isolates of ST8 and 8 MRSA isolates and 8 MSSA isolates of ST5 were characterized with respect to multilocus sequence type; agr, spa, and capsule typing; in vitro doubling time; toxin and adhesin gene profiles; and adherence to HAECs. Adherence was significantly lower in the MRSA ST5 group than in the ST8 groups. Infections with MRSA and MSSA isolates ST8 and ST5 were compared. No change in virulence related to the presence of SCCmec was observed, since ST8 but not ST5 caused a significantly lower mortality in its presence. Despite their similar genetic backgrounds, individual clonal MRSA and MSSA isolates were heterogeneous in adherence and virulence. No one of these specific virulence factors determined in vitro was related to mouse mortality. In conclusion, in a bacteremic model, mortality was dependent on the ST and was differentially modulated by SCCmec; within an ST, clonality was not associated with a homogenous outcome.

scholarly journals Novel Type of Staphylococcal Cassette Chromosome mec Identified in Community-Acquired Methicillin-Resistant Staphylococcus aureus Strains

2002 ◽  
Vol 46 (4) ◽  
pp. 1147-1152 ◽  
Author(s):  
Xiao Xue Ma ◽  
Teruyo Ito ◽  
Chuntima Tiensasitorn ◽  
Mantana Jamklang ◽  
Piriyaporn Chongtrakool ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Antibiotic Resistance Genes ◽  
Gene Complex ◽  
Methicillin Resistant ◽  
Type Iv ◽  
Class B ◽  
New Type ◽  
Mrsa Strains ◽  
Hospital Acquired ◽  
Staphylococcal Cassette Chromosome

ABSTRACT We identified a new type of staphylococcal cassette chromosome mec (SCCmec) from two community-acquired methicillin-resistant Staphylococcus aureus (MRSA) strains. The novel element, designated type IV SCCmec, had a unique combination of the class B mec gene complex and the type 2 ccr gene complex and was much smaller in size (21 to 24 kb) than previously identified SCCmec elements of hospital-acquired MRSA. Consistent with the strains' susceptibilities to various non-β-lactam antibiotics, the type IV SCCmec was devoid of any antibiotic resistance genes other than the mecA gene.

scholarly journals In Vitro Killing of Community-Associated Methicillin-Resistant Staphylococcus aureus with Drug Combinations

2004 ◽  
Vol 48 (10) ◽  
pp. 4016-4019 ◽  
Author(s):  
Samuel A. Shelburne ◽  
Daniel M. Musher ◽  
Kristina Hulten ◽  
Heather Ceasar ◽  
Michael Y. Lu ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Drug Combinations ◽  
Methicillin Resistant ◽  
Common Drug ◽  
Time Kill ◽  
Hospital Acquired

ABSTRACT This study employs time-kill techniques to examine the most common drug combinations used in the therapy of methicillin-resistant Staphylococcus aureus (MRSA) infections, vancomycin plus either gentamicin or rifampin. Community-associated MRSA were more likely to be synergistically inhibited by combinations of vancomycin and gentamicin versus vancomycin alone compared to inhibition associated with hospital-acquired strains.

scholarly journals The Virulence Potential of Livestock-Associated Methicillin-Resistant Staphylococcus aureus Cultured from the Airways of Cystic Fibrosis Patients

Toxins ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 360
Author(s):  
Janina Treffon ◽  
Sarah Ann Fotiadis ◽  
Sarah van Alen ◽  
Karsten Becker ◽  
Barbara C. Kahl
Keyword(s):  
Cystic Fibrosis ◽  
Staphylococcus Aureus ◽  
Airway Epithelial Cells ◽  
Farm Animals ◽  
Airway Epithelial ◽  
Methicillin Resistant ◽  
Virulence Potential ◽  
Airway Infections ◽  
Severe Infections

Staphylococcus aureus is one of the most common pathogens that infects the airways of patients with cystic fibrosis (CF) and contributes to respiratory failure. Recently, livestock-associated methicillin-resistant S. aureus (LA-MRSA), usually cultured in farm animals, were detected in CF airways. Although some of these strains are able to establish severe infections in humans, there is limited knowledge about the role of LA-MRSA virulence in CF lung disease. To address this issue, we analyzed LA-MRSA, hospital-associated (HA-) MRSA and methicillin-susceptible S. aureus (MSSA) clinical isolates recovered early in the course of airway infection and several years after persistence in this hostile environment from pulmonary specimens of nine CF patients regarding important virulence traits such as their hemolytic activity, biofilm formation, invasion in airway epithelial cells, cytotoxicity, and antibiotic susceptibility. We detected that CF LA-MRSA isolates were resistant to tetracycline, more hemolytic and cytotoxic than HA-MRSA, and more invasive than MSSA. Despite the residence in the animal host, LA-MRSA still represent a serious threat to humans, as such clones possess a virulence potential similar or even higher than that of HA-MRSA. Furthermore, we confirmed that S. aureus individually adapts to the airways of CF patients, which eventually impedes the success of antistaphylococcal therapy of airway infections in CF.

scholarly journals A Multicenter Study To Evaluate Ceftaroline Breakpoints: Performance in an Area with High Prevalence of Methicillin-Resistant Staphylococcus aureus Sequence Type 5 Lineage

2019 ◽  
Vol 57 (9) ◽  
Author(s):  
Ayesha Khan ◽  
Lina M. Rivas ◽  
Maria Spencer ◽  
Rodrigo Martinez ◽  
Marusella Lam ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Sequence Type ◽  
Disk Diffusion ◽  
Clinical Settings ◽  
Community Settings ◽  
Methicillin Resistant ◽  
Content Type ◽  
Bmd Testing ◽  
High Prevalence

ABSTRACT Ceftaroline (CPT) is a broad-spectrum agent with potent activity against methicillin-resistant Staphylococcus aureus (MRSA). The sequence type 5 (ST5) Chilean-Cordobés clone, associated with CPT nonsusceptibility, is dominant in Chile, a region with high rates of MRSA infections. Here, we assessed the in vitro activity of CPT against a collection of MRSA isolates collected between 1999 and 2018 from nine hospitals (n = 320) and community settings (n = 41) in Santiago, Chile, and evaluated performance across testing methodologies. We found that our hospital-associated isolates exhibited higher CPT MIC distributions (MIC50 and MIC90 of 2 mg/liter) than the community isolates (MIC50 and MIC90 of 0.5 mg/liter), a finding that was consistent across time and independent of the culture source. High proportions (64%) of isolates were CPT nonsusceptible despite the absence of CPT use in Chile. Across methodologies, the Etest underestimated the MIC relative to the gold standard broth microdilution (BMD) test (MIC50 and MIC90 of 1 and 1.5 mg/liter, respectively). There was low (∼51%) categorical agreement (CA) between Etest and BMD results across CLSI and EUCAST breakpoints. The recent revision of CLSI guidelines abolished “very major error” (VME) from the previous guidelines (81%), which perform similarly to the EUCAST guidelines. The level of concordance between CLSI and EUCAST for BMD testing and Etest was >95%. Disk diffusion performed poorly relative to BMD under CLSI (CA, 55%) and EUCAST (CA, 36%) guidelines. Comparison of EUCAST to CLSI for disk diffusion (with EUCAST used as the reference) showed low agreement (CA, 25%; VME, 70%). In summary, CPT-nonsusceptible MRSA are dominant in clinical settings in Chile. Our results provide data to support the reevaluation of CPT breakpoints and to improve agreement across methodologies and agencies.

scholarly journals Comparative Molecular Analysis of Community- or Hospital-Acquired Methicillin-Resistant Staphylococcus aureus

2003 ◽  
Vol 47 (1) ◽  
pp. 196-203 ◽  
Author(s):  
P. D. Fey ◽  
B. Saïd-Salim ◽  
M. E. Rupp ◽  
S. H. Hinrichs ◽  
D. J. Boxrud ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Genetic Relatedness ◽  
Health Concern ◽  
Toxic Shock ◽  
Methicillin Resistant ◽  
Type Iv ◽  
Antibiotic Susceptibility Patterns ◽  
Mrsa Strains ◽  
Hospital Acquired ◽  
Susceptibility Patterns

ABSTRACT Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is a growing public health concern that has been associated with pediatric fatalities. It is hypothesized that the evolution of CA-MRSA is a recent event due to the acquisition of mec DNA by previously methicillin-susceptible strains that circulated in the community. This study investigated the genetic relatedness between CA-MRSA, hospital-associated MRSA (HA-MRSA), and nonmenstrual toxic shock syndrome (nmTSS) isolates. Thirty-one of 32 CA-MRSA isolates were highly related as determined by pulsed-field gel electrophoresis and spa typing yet were distinguishable from 32 HA-MRSA strains. The 31 related CA-MRSA isolates produced either staphylococcal enterotoxin B (n = 5) or C (n = 26), and none made TSS toxin 1. All CA-MRSA isolates tested contained a type IV staphylococcal cassette chromosome mec (SCCmec) element. In comparison, none of the HA-MRSA isolates (n = 32) expressed the three superantigens. Antibiotic susceptibility patterns were different between the CA-MRSA and HA-MRSA isolates; CA-MRSA was typically resistant only to β-lactam antibiotics. Six of twenty-one nmTSS isolates were indistinguishable or highly related to the CA-MRSA isolates. MnCop, an nmTSS isolate obtained in Alabama in 1986, was highly related to the CA-MRSA isolates except that it did not contain an SCCmec element. These data suggest that CA-MRSA strains may represent a new acquisition of SCCmec DNA in a previously susceptible genetic background that was capable of causing nmTSS. CA-MRSA poses a serious health risk not only because it is resistant to the antibiotics of choice for community-acquired staphylococcal infections but also because of its ability to cause nmTSS via superantigen production.

scholarly journals In Vitro Activity of Iclaprim against Methicillin-Resistant Staphylococcus aureus Nonsusceptible to Daptomycin, Linezolid, or Vancomycin: A Pilot Study

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
David B. Huang ◽  
Stephen Hawser ◽  
Curtis G. Gemmell ◽  
Daniel F. Sahm
Keyword(s):  
Staphylococcus Aureus ◽  
Pilot Study ◽  
Bacterial Resistance ◽  
Phase 3 ◽  
Methicillin Resistant ◽  
Gram Positive Bacteria ◽  
Serious Infections ◽  
Time Kill ◽  
Hospital Acquired

Iclaprim is a bacterial dihydrofolate reductase inhibitor in Phase 3 clinical development for the treatment of acute bacterial skin and skin structure infections and hospital-acquired bacterial pneumonia caused by Gram-positive bacteria. Daptomycin, linezolid, and vancomycin are commonly used antibiotics for these indications. With increased selective pressure to these antibiotics, outbreaks of bacterial resistance to these antibiotics have been reported. This in vitro pilot study evaluated the activity of iclaprim against methicillin-resistant Staphylococcus aureus (MRSA) isolates, which were also not susceptible to daptomycin, linezolid, or vancomycin. Iclaprim had an MIC ≤ 1 µg/ml to the majority of MRSA isolates that were nonsusceptible to daptomycin (5 of 7 (71.4%)), linezolid (26 of 26 (100%)), or vancomycin (19 of 28 (66.7%)). In the analysis of time-kill curves, iclaprim demonstrated ≥ 3 log10 reduction in CFU/mL at 4–8 hours for tested strains and isolates nonsusceptible to daptomycin, linezolid, or vancomycin. Together, these data support the use of iclaprim in serious infections caused by MRSA nonsusceptible to daptomycin, linezolid, or vancomycin.

scholarly journals First Report ofcfr-Carrying Plasmids in the Pandemic Sequence Type 22 Methicillin-Resistant Staphylococcus aureus Staphylococcal Cassette ChromosomemecType IV Clone

2016 ◽  
Vol 60 (5) ◽  
pp. 3007-3015 ◽  
Author(s):  
Anna C. Shore ◽  
Alexandros Lazaris ◽  
Peter M. Kinnevey ◽  
Orla M. Brennan ◽  
Gráinne I. Brennan ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Ribosomal Proteins ◽  
Resistance Mechanisms ◽  
Sequence Type ◽  
23S Rrna ◽  
Methicillin Resistant ◽  
Content Type ◽  
First Report ◽  
Type Iv ◽  
Linezolid Resistance

ABSTRACTLinezolid is often the drug of last resort for serious methicillin-resistantStaphylococcus aureus(MRSA) infections. Linezolid resistance is mediated by mutations in 23S rRNA and genes for ribosomal proteins;cfr, encoding phenicol, lincosamide, oxazolidinone, pleuromutilin, and streptogramin A (PhLOPSA) resistance; its homologuecfr(B); oroptrA, conferring oxazolidinone and phenicol resistance. Linezolid resistance is rare inS. aureus, andcfris even rarer. This study investigated the clonality and linezolid resistance mechanisms of two MRSA isolates from patients in separate Irish hospitals. Isolates were subjected tocfrPCR, PhLOPSAsusceptibility testing, 23S rRNA PCR and sequencing, DNA microarray profiling,spatyping, pulsed-field gel electrophoresis (PFGE), plasmid curing, and conjugative transfer. Whole-genome sequencing was used for single-nucleotide variant (SNV) analysis, multilocus sequence typing, L protein mutation identification,cfrplasmid sequence analysis, andoptrAandcfr(B) detection. Isolates M12/0145 and M13/0401 exhibited linezolid MICs of 64 and 16 mg/liter, respectively, and harbored identical 23S rRNA and L22 mutations, but M12/0145 exhibited the mutation in 2/6 23S rRNA alleles, compared to 1/5 in M13/0401. Both isolates were sequence type 22 MRSA staphylococcal cassette chromosomemectype IV (ST22-MRSA-IV)/spatype t032 isolates, harboredcfr, exhibited the PhLOPSAphenotype, and lackedoptrAandcfr(B). They differed by five PFGE bands and 603 SNVs. Isolate M12/0145 harboredcfrandfexAon a 41-kb conjugative pSCFS3-type plasmid, whereas M13/0401 harboredcfrandlsa(B) on a novel 27-kb plasmid. This is the first report ofcfrin the pandemic ST22-MRSA-IV clone. Differentcfrplasmids and mutations associated with linezolid resistance in genotypically distinct ST22-MRSA-IV isolates highlight that prudent management of linezolid use is essential.

scholarly journals Methicillin-Resistant Staphylococcus aureus Sequence Type (ST) 5 Isolates from Health Care and Agricultural Sources Adhere Equivalently to Human Keratinocytes

2017 ◽  
Vol 84 (2) ◽  
Author(s):  
Samantha J. Hau ◽  
Steven Kellner ◽  
Kirsten C. Eberle ◽  
Ursula Waack ◽  
Susan L. Brockmeier ◽  
...  
Keyword(s):  
Public Health ◽  
Staphylococcus Aureus ◽  
Human Skin ◽  
Hospital Setting ◽  
Human Keratinocytes ◽  
The United States ◽  
Sequence Type ◽  
Methicillin Resistant ◽  
Content Type

ABSTRACT Staphylococcus aureus is part of the nasal microbiome of many humans and has become a significant public health burden due to infections with antibiotic-resistant strains, including methicillin-resistant S. aureus (MRSA) strains. Several lineages of S. aureus, including MRSA, are found in livestock species and can be acquired by humans through contact with animals. These livestock-associated MRSA (LA-MRSA) isolates raise public health concerns because of the potential for livestock to act as reservoirs for MRSA outside the hospital setting. In the United States, swine harbor a mixed population of LA-MRSA isolates, with the sequence type 398 (ST398), ST9, and ST5 lineages being detected. LA-MRSA ST5 isolates are particularly concerning to the public health community because, unlike the isolates in the ST398 and ST9 lineages, isolates in the ST5 lineage are a significant cause of human disease in both the hospital and community settings globally. The ability of swine-associated LA-MRSA ST5 isolates to adhere to human keratinocytes in vitro was investigated, and the adherence genes harbored by these isolates were evaluated and compared to those in clinical MRSA ST5 isolates from humans with no swine contact. The two subsets of isolates adhered equivalently to human keratinocytes in vitro and contained an indistinguishable complement of adherence genes that possessed a high degree of sequence identity. Collectively, our data indicate that, unlike LA-MRSA ST398 isolates, LA-MRSA ST5 isolates do not exhibit a reduced genotypic or phenotypic capacity to adhere to human keratinocytes. IMPORTANCE Our data indicate that swine-associated livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) ST5 isolates are as capable of adhering to human skin and have the same genetic potential to adhere as clinical MRSA ST5 isolates from humans. This suggests that humans in contact with livestock have the potential to become colonized with LA-MRSA ST5 isolates; however, the genes that contribute to the persistence of S. aureus on human skin were absent in LA-MRSA ST5 isolates. The data presented here are important evidence in evaluating the potential risks that LA-MRSA ST5 isolates pose to humans who come into contact with livestock.

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