scholarly journals Derivatives of a Vancomycin-Resistant Staphylococcus aureus Strain Isolated at Hershey Medical Center

2004 ◽  
Vol 48 (12) ◽  
pp. 4762-4765 ◽  
Author(s):  
Bülent Bozdogan ◽  
Lois Ednie ◽  
Kim Credito ◽  
Klaudia Kosowska ◽  
Peter C. Appelbaum
Keyword(s):  
Staphylococcus Aureus ◽  
Genetic Relatedness ◽  
Medical Center ◽  
Aureus Strain ◽  
Original Culture ◽  
Vancomycin Mics ◽  
Allele Variant ◽  
Vancomycin Resistant ◽  
High Level ◽  
Derivatives Of

ABSTRACT Antimicrobial susceptibilities and genetic relatedness of the vancomycin-resistant Staphylococcus aureus strain (VRSA) isolated at Hershey, Pa. (VRSA Hershey), and its vancomycin-susceptible and high-level-resistant derivatives were studied and compared to 32 methicillin-resistant S. aureus strains (MRSA) isolated from patients and medical staff in contact with the VRSA patient. Derivatives of VRSA were obtained by subculturing six VRSA colonies from the original culture with or without vancomycin. Ten days of drug-free subculture caused the loss of vanA in two vancomycin-susceptible derivatives for which vancomycin MICs were 1 to 4 μg/ml. Multistep selection of three VRSA clones with vancomycin for 10 days increased vancomycin MICs from 32 to 1,024 to 2,048 μg/ml. MICs of teicoplanin, dalbavancin, and oritavancin were also increased from 4, 0.5, and 0.12 to 64, 1, and 32 μg/ml, respectively. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing analysis indicated that VRSA Hershey was the vanA-acquired variety of a common MRSA clone in our hospital with sequence type 5 (ST5). Three of five vancomycin-intermediate S. aureus strains tested from geographically different areas were also ST5, and the Michigan VRSA was ST371, a one-allele variant of ST5. Derivatives of VRSA Hershey had differences in PFGE profiles and the size of SmaI fragment that carries the vanA gene cluster, indicating instability of this cluster in VRSA Hershey. However induction with vancomycin increased glycopeptide MICs and stabilized the resistance.

scholarly journals High-Level Vancomycin-Resistant Staphylococcus aureus Isolates Associated with a Polymicrobial Biofilm

2006 ◽  
Vol 51 (1) ◽  
pp. 231-238 ◽  
Author(s):  
Linda M. Weigel ◽  
Rodney M. Donlan ◽  
Dong Hyeon Shin ◽  
Bette Jensen ◽  
Nancye C. Clark ◽  
...  
Keyword(s):  
New York ◽  
Staphylococcus Aureus ◽  
Resistance Genes ◽  
Bacterial Species ◽  
Tetracycline Resistance ◽  
Aminoglycoside Resistance ◽  
Antimicrobial Resistance Genes ◽  
Vancomycin Mics ◽  
Vancomycin Resistant ◽  
High Level

ABSTRACT Glycopeptides such as vancomycin are the treatment of choice for infections due to methicillin-resistant Staphylococcus aureus. This study describes the identification of high-level vancomycin-resistant S. aureus (VRSA) isolates in a polymicrobial biofilm within an indwelling nephrostomy tube in a patient in New York. S. aureus, Enterococcus faecalis, Enterococcus faecium, Micrococcus species, Morganella morganii, and Pseudomonas aeruginosa were isolated from the biofilm. For VRSA isolates, vancomycin MICs ranged from 32 to >128 μg/ml. VRSA isolates were also resistant to aminoglycosides, fluoroquinolones, macrolides, penicillin, and tetracycline but remained susceptible to chloramphenicol, linezolid, rifampin, and trimethoprim-sulfamethoxazole. The vanA gene was localized to a plasmid of ∼100 kb in VRSA and E. faecium isolates from the biofilm. Plasmid analysis revealed that the VRSA isolate acquired the 100-kb E. faecium plasmid, which was then maintained without integration into the MRSA plasmid. The tetracycline resistance genes tet(U) and tet(S), not previously detected in S. aureus isolates, were identified in the VRSA isolates. Additional resistance elements in the VRSA isolate included a multiresistance gene cluster, ermB-aadE-sat4-aphA-3, msrA (macrolide efflux), and the bifunctional aminoglycoside resistance gene aac(6′)-aph(2")-Ia. Multiple combinations of resistance genes among the various isolates of staphylococci and enterococci, including vanA, tet(S), and tet(U), illustrate the dynamic nature of gene acquisition and loss within and between bacterial species throughout the course of infection. The potential for interspecies transfer of antimicrobial resistance genes, including resistance to vancomycin, may be enhanced by the microenvironment of a biofilm.

scholarly journals Characterization of Passage-Selected Vancomycin-Resistant Staphylococcus aureus Strains of Diverse Parental Backgrounds

2000 ◽  
Vol 44 (2) ◽  
pp. 294-303 ◽  
Author(s):  
Richard F. Pfeltz ◽  
Vineet K. Singh ◽  
Jennifer L. Schmidt ◽  
Michael A. Batten ◽  
Christopher S. Baranyk ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Walls ◽  
Methicillin Resistance ◽  
Surface Hydrophobicity ◽  
Whole Cell ◽  
Transmission Electron ◽  
Vancomycin Mics ◽  
Vancomycin Resistant ◽  
Doubling Times

ABSTRACT A series of 12 Staphylococcus aureus strains of various genetic backgrounds, methicillin resistance levels, and autolytic activities were subjected to selection for the glycopeptide-intermediate S. aureus (GISA) susceptibility phenotype on increasing concentrations of vancomycin. Six strains acquired the phenotype rapidly, two did so slowly, and four failed to do so. The vancomycin MICs for the GISA strains ranged from 4 to 16 μg/ml, were stable to 20 nonselective passages, and expressed resistance homogeneously. Neither ease of acquisition of the GISA phenotype nor the MIC attained correlated with methicillin resistance hetero- versus homogeneity or autolytic deficiency or sufficiency. Oxacillin MICs were generally unchanged between parent and GISA strains, although the mec members of both isogenic methicillin-susceptible and methicillin-resistant pairs acquired the GISA phenotype more rapidly and to higher MICs than did their susceptible counterparts. Transmission electron microscopy revealed that the GISA strains appeared normal in the absence of vancomycin but had thickened and diffuse cell walls when grown with vancomycin at one-half the MIC. Common features among GISAs were reduced doubling times, decreased lysostaphin susceptibilities, and reduced whole-cell and zymographic autolytic activities in the absence of vancomycin. This, with surface hydrophobicity differences, indicated that even in the absence of vancomycin the GISA cell walls differed from those of the parents. Autolytic activities were further reduced by the inclusion of vancomycin in whole-cell and zymographic studies. The six least vancomycin-susceptible GISA strains exhibited an increased capacity to remove vancomycin from the medium versus their parent lines. This study suggests that while some elements of the GISA phenotype are strain specific, many are common to the phenotype although their expression is influenced by genetic background. GISA strains with similar glycopeptide MICs may express individual components of the phenotype to different extents.

scholarly journals Genetic Analysis of a Vancomycin-Resistant Staphylococcus aureus Strain Isolated in Iran

mBio ◽  
2012 ◽  
Vol 3 (6) ◽  
Author(s):  
Amir Azimian ◽  
Seyed Asghar Havaei ◽  
Hosein Fazeli ◽  
Mahmood Naderi ◽  
Kiarash Ghazvini ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Genetic Analysis ◽  
Aureus Strain ◽  
Vancomycin Resistant

scholarly journals Penicillin-Binding Protein 2 Is Essential for Expression of High-Level Vancomycin Resistance and Cell Wall Synthesis in Vancomycin- Resistant Staphylococcus aureus Carrying the Enterococcal vanA Gene Complex

2004 ◽  
Vol 48 (12) ◽  
pp. 4566-4573 ◽  
Author(s):  
Anatoly Severin ◽  
Shang Wei Wu ◽  
Keiko Tabei ◽  
Alexander Tomasz
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Binding Protein ◽  
Inducible Promoter ◽  
Protein Product ◽  
Vancomycin Resistance ◽  
Penicillin Binding Protein ◽  
Oxacillin Resistance ◽  
Vancomycin Resistant ◽  
High Level

ABSTRACT A combination of biochemical and genetic experiments were performed in order to better understand the mechanism of expression of high-level vancomycin resistance in Staphylococcus aureus. The transcription of pbp2 of the highly vancomycin- and oxacillin-resistant strain COLVA200 and its mutant derivative with inactivated mecA were put under the control of an inducible promoter, and the dependence of oxacillin and vancomycin resistance and cell wall composition on the concentration of the isopropyl-β-d-thiogalactopyranoside inducer was determined. The results indicate that mecA—the genetic determinant of oxacillin resistance—while essential for oxacillin resistance, is not involved with the expression of vancomycin resistance. Penicillin binding protein 2A, the protein product of mecA, appears to be unable to utilize the depsipeptide cell wall precursor produced in the vancomycin-resistant cells for transpeptidation. The key penicillin binding protein essential for vancomycin resistance and for the synthesis of the abnormally structured cell walls characteristic of vancomycin-resistant S. aureus (A. Severin, K. Tabei, F. Tenover, M. Chung, N. Clarke, and A. Tomasz, J. Biol. Chem. 279:3398-3407, 2004) is penicillin binding protein 2.

scholarly journals Comparison of Tn1546-Like Elements in Vancomycin-Resistant Staphylococcus aureus Isolates from Michigan and Pennsylvania

2005 ◽  
Vol 49 (1) ◽  
pp. 470-472 ◽  
Author(s):  
Nancye C. Clark ◽  
Linda M. Weigel ◽  
Jean B. Patel ◽  
Fred C. Tenover
Keyword(s):  
Staphylococcus Aureus ◽  
Sequence Analysis ◽  
Dna Sequence ◽  
Intergenic Region ◽  
Mobile Genetic Element ◽  
Clinical Isolates ◽  
Genetic Element ◽  
Vancomycin Resistant ◽  
High Level ◽  
Genetic Events

ABSTRACT In 2002, the first two clinical isolates of vancomycin-resistant Staphylococcus aureus (VRSA) containing vanA were recovered in Michigan and Pennsylvania. Tn1546, a mobile genetic element that encodes high-level vancomycin resistance in enterococci, was present in both isolates. With PCR and DNA sequence analysis, we compared the Tn1546 elements from each isolate to the prototype Tn1546 element. The Michigan VRSA element was identical to the prototype Tn1546 element. The Pennsylvania VRSA element showed three distinct modifications: a deletion of nucleotides 1 to 3098 at the 5′ end, which eliminated the orf1 region; an 809-bp IS1216V-like element inserted before nucleotide 3099 of Tn1546; and an inverted 1,499-bp IS1251-like element inserted into the vanSH intergenic region. These differences in the Tn1546-like elements indicate that the first two VRSA isolates were the result of independent genetic events.

ID: 49: STUDY OF MINIMUM INHIBITORY CONCENTRATION OF CEFAZOLIN FOR METHICILLIN SENSITIVE STAPHYLOCOCCUS AUREUS AND CORRELATION WITH OXACILLIN SUSCEPTIBILITY

2016 ◽  
Vol 64 (4) ◽  
pp. 954.2-954
Author(s):  
C Quarshie ◽  
J Koirala ◽  
V Sundareshan
Keyword(s):  
Staphylococcus Aureus ◽  
Standard Deviation ◽  
Minimum Inhibitory Concentration ◽  
Inhibitory Concentration ◽  
Medical Center ◽  
Generation Cephalosporin ◽  
In Vitro Susceptibility ◽  
Suitable Alternative ◽  
High Level

BackgroundCefazolin, a first generation cephalosporin, has been used for the treatment of Methicillin Sensitive Staphylococcus aureus (MSSA) infections since the 1970s. There have now been reported cases of failed therapy with cefazolin. High-level β-lactamase producing strains of S. aureus can inactivate the susceptible β-lactam (cefazolin) at a rate high enough to overcome its antibacterial effect. These strains typically have a high Minimum Inhibitory Concentration (MIC) for cefazolin when a large inoculum is used. About 20% of MSSA isolates have been shown to have a substantial inoculum effect suggesting that cefazolin treatment might be associated with clinical failure in serious MSSA infections. The minimum inhibition concentration (MIC) for cefazolin is not provided on all standard sensitivity panels and susceptibility is extrapolated from the report on oxacillin. The goal of this study was to analyze the MIC of cefazolin for MSSA isolates to determine the correlation of cefazolin susceptibility and in vitro susceptibility of oxacillin. We also evaluated the MIC of alternative antibiotics as part of this study for use in patients that might be allergic to penicillin.MethodThirty two isolates of MSSA were randomly selected from repositories of isolates at Memorial Medical Center hospital's microbiology department from 2015. The isolates were from patients with a wide variety of diagnoses, including bacteremia, osteomyelitis and wound infections. S. aureus ATCC 29213 was used as controls. MICs were determined by a Kirby Bauer method for cefazolin and Epsilometer test for other antibiotics that were studied. Inocula were standardized using optical density measurements, with determinations of CFU/ml to determine the inoculum concentrations. IN addition to cefazolin, we obtained the MIC for daptomycin, oxacillin, ceftaroline and telavancin as well.ResultsOf the thirty two MSSA isolates tested, 100% were susceptible to cefazolin. The mean zone of inhibition (ZOI) was 29.18 with standard deviation of 3.67 for cefazolin (29–35 mm ZOI with ATCC strains of MSSA) . All the isolates were susceptible to Oxacillin with mean MIC of 0.7735 with standard deviation of 0.30. Daptomycin, ceftaroline and telavancin were 100% susceptible with mean MIC of 0.27, 0.25, and 0.07, respectively. All isolates were studied for the alternate antibiotics and no resistance was noted.ConclusionThe MIC of cefazolin for MSSA determined by in vitro susceptibility to oxacillin was entirely in the susceptible range with 100% correlation. Daptomycin, ceftaroline and telavancin are suitable alternative antibiotics for treatment of patients with infections due to MSSA in whom anti-staphylococcal penicillins cannot be used due to penicillin allergic, intolerance, and/or non-availability since there is not much resistance to these antibiotics in MSSA.

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