scholarly journals Characterization of Nasal and Blood Culture Isolates of Methicillin-Resistant Staphylococcus aureus from Patients in United States Hospitals

2011 ◽  
Vol 56 (3) ◽  
pp. 1324-1330 ◽  
Author(s):  
Fred C. Tenover ◽  
Isabella A. Tickler ◽  
Richard V. Goering ◽  
Barry N. Kreiswirth ◽  
José R. Mediavilla ◽  
...  
Keyword(s):  
United States ◽  
Staphylococcus Aureus ◽  
The United States ◽  
United States Census ◽  
Convenience Sample ◽  
Methicillin Resistant ◽  
Content Type ◽  
Type Iv ◽  
Strain Type ◽  
High Level

ABSTRACTA total of 299 nares and 194 blood isolates of methicillin-resistantStaphylococcus aureus(MRSA), each recovered from a unique patient, were collected from 23 U.S. hospitals from May 2009 to March 2010. All isolates underwentspaand staphylococcal cassette chromosomemecelement (SCCmec) typing and antimicrobial susceptibility testing; a subset of 84 isolates was typed by pulsed-field gel electrophoresis (PFGE) using SmaI. Seventy-sixspatypes were observed among the isolates. Overall, for nasal isolates,spatype t002-SCCmectype II (USA100) was the most common strain type (37% of isolates), while among blood isolates,spatype t008-SCCmectype IV (USA300) was the most common (39%). However, the proportion of all USA100 and USA300 isolates varied by United States census region. Nasal isolates were more resistant to tobramycin and clindamycin than blood isolates (55.9% and 48.8% of isolates versus 36.6% and 39.7%, respectively; for both,P< 0.05). The USA300 isolates were largely resistant to fluoroquinolones. High-level mupirocin resistance was low among allspatypes (<5%). SCCmectypes III and VIII, which are rare in the United States, were observed along with several unusual PFGE types, including CMRSA9, EMRSA15, and the PFGE profile associated with sequence type 239 (ST239) isolates. Typing data from this convenience sample suggest that in U.S. hospitalized patients, USA100 isolates of multiplespatypes, while still common in the nares, have been replaced by USA300 isolates as the predominant MRSA strain type in positive blood cultures.

scholarly journals Activity of Ceftaroline and Epidemiologic Trends in Staphylococcus aureus Isolates Collected from 43 Medical Centers in the United States in 2009

2011 ◽  
Vol 55 (9) ◽  
pp. 4154-4160 ◽  
Author(s):  
Sandra S. Richter ◽  
Kristopher P. Heilmann ◽  
Cassie L. Dohrn ◽  
Fathollah Riahi ◽  
Andrew J. Costello ◽  
...  
Keyword(s):  
United States ◽  
Staphylococcus Aureus ◽  
The United States ◽  
Surveillance Program ◽  
Content Type ◽  
Type Iv ◽  
Medical Centers ◽  
High Level ◽  
Resistance Rates

ABSTRACTAStaphylococcus aureussurveillance program was initiated in the United States to examine thein vitroactivity of ceftaroline and epidemiologic trends. Susceptibility testing by Clinical and Laboratory Standards Institute broth microdilution was performed on 4,210 clinically significant isolates collected in 2009 from 43 medical centers. All isolates were screened formecAby PCR and evaluated by pulsed-field gel electrophoresis. Methicillin-resistantS. aureus(MRSA) were analyzed for Panton-Valentine leukocidin (PVL) genes and the staphylococcal cassette chromosomemec(SCCmec) type. All isolates had ceftaroline MICs of ≤2 μg/ml with an MIC50of 0.5 and an MIC90of 1 μg/ml. The overall resistance rates, expressed as the percentages of isolates that were intermediate and resistant (or nonsusceptible), were as follows: ceftaroline, 1.0%; clindamycin, 30.2% (17.4% MIC ≥ 4 μg/ml; 12.8% inducible); daptomycin, 0.2%; erythromycin, 65.5%; levofloxacin, 39.9%; linezolid, 0.02%; oxacillin, 53.4%; tetracycline, 4.4%; tigecycline, 0%; trimethoprim-sulfamethoxazole, 1.6%; vancomycin, 0%; and high-level mupirocin, 2.2%. ThemecAPCR was positive for 53.4% of the isolates. The ceftaroline MIC90s were 0.25 μg/ml for methicillin-susceptibleS. aureusand 1 μg/ml for MRSA. Among the 2,247 MRSA isolates, 51% were USA300 (96.9% PVL positive, 99.7% SCCmectype IV) and 17% were USA100 (93.4% SCCmectype II). The resistance rates for the 1,137 USA300 MRSA isolates were as follows: erythromycin, 90.9%; levofloxacin, 49.1%; clindamycin, 7.6% (6.2% MIC ≥ 4 μg/ml; 1.4% inducible); tetracycline, 3.3%; trimethoprim-sulfamethoxazole, 0.8%; high-level mupirocin, 2.7%; daptomycin, 0.4%; and ceftaroline and linezolid, 0%. USA300 is the dominant clone causing MRSA infections in the United States. Ceftaroline demonstrated potentin vitroactivity against recentS. aureusclinical isolates, including MRSA, daptomycin-nonsusceptible, and linezolid-resistant strains.

scholarly journals PBP2a Mutations Causing High-Level Ceftaroline Resistance in Clinical Methicillin-Resistant Staphylococcus aureus Isolates

2014 ◽  
Vol 58 (11) ◽  
pp. 6668-6674 ◽  
Author(s):  
S. Wesley Long ◽  
Randall J. Olsen ◽  
Shrenik C. Mehta ◽  
Timothy Palzkill ◽  
Patricia L. Cernoch ◽  
...  
Keyword(s):  
United States ◽  
Staphylococcus Aureus ◽  
Binding Pocket ◽  
The United States ◽  
Penicillin Binding Protein ◽  
Methicillin Resistant ◽  
Content Type ◽  
Mrsa Strains ◽  
Biochemical Analyses ◽  
High Level

ABSTRACTCeftaroline is the first member of a novel class of cephalosporins approved for use in the United States. Although prior studies have identified eight ceftaroline-resistant methicillin-resistantStaphylococcus aureus(MRSA) isolates in Europe and Asia with MICs ranging from 4 to 8 mg/liter, high-level resistance to ceftaroline (>32 mg/liter) has not been described in MRSA strains isolated in the United States. We isolated a ceftaroline-resistant (MIC > 32 mg/liter) MRSA strain from the blood of a cystic fibrosis patient and five MRSA strains from the respiratory tract of this patient. Whole-genome sequencing identified two amino acid-altering mutations uniquely present in the ceftaroline-binding pocket of the transpeptidase region of penicillin-binding protein 2a (PBP2a) in ceftaroline-resistant isolates. Biochemical analyses and the study of isogenic mutant strains confirmed that these changes caused ceftaroline resistance. Thus, we identified the molecular mechanism of ceftaroline resistance in the first MRSA strain with high-level ceftaroline resistance isolated in the United States.

scholarly journals Comparative Genomics of Vancomycin-Resistant Staphylococcus aureus Strains and Their Positions within the Clade Most Commonly Associated with Methicillin-Resistant S. aureus Hospital-Acquired Infection in the United States

mBio ◽  
2012 ◽  
Vol 3 (3) ◽  
Author(s):  
Veronica N. Kos ◽  
Christopher A. Desjardins ◽  
Allison Griggs ◽  
Gustavo Cerqueira ◽  
Andries Van Tonder ◽  
...  
Keyword(s):  
United States ◽  
Staphylococcus Aureus ◽  
The United States ◽  
Methicillin Resistant ◽  
Content Type ◽  
Mrsa Infection ◽  
Vancomycin Resistant ◽  
Foreign Dna ◽  
Mrsa Strains ◽  
Hospital Acquired

ABSTRACTMethicillin-resistantStaphylococcus aureus(MRSA) strains are leading causes of hospital-acquired infections in the United States, and clonal cluster 5 (CC5) is the predominant lineage responsible for these infections. Since 2002, there have been 12 cases of vancomycin-resistantS. aureus(VRSA) infection in the United States—all CC5 strains. To understand this genetic background and what distinguishes it from other lineages, we generated and analyzed high-quality draft genome sequences for all available VRSA strains. Sequence comparisons show unambiguously that each strain independently acquired Tn1546and that all VRSA strains last shared a common ancestor over 50 years ago, well before the occurrence of vancomycin resistance in this species. In contrast to existing hypotheses on what predisposes this lineage to acquire Tn1546, the barrier posed by restriction systems appears to be intact in most VRSA strains. However, VRSA (and other CC5) strains were found to possess a constellation of traits that appears to be optimized for proliferation in precisely the types of polymicrobic infection where transfer could occur. They lack a bacteriocin operon that would be predicted to limit the occurrence of non-CC5 strains in mixed infection and harbor a cluster of unique superantigens and lipoproteins to confound host immunity. A frameshift indprA, which in other microbes influences uptake of foreign DNA, may also make this lineage conducive to foreign DNA acquisition.IMPORTANCEInvasive methicillin-resistantStaphylococcus aureus(MRSA) infection now ranks among the leading causes of death in the United States. Vancomycin is a key last-line bactericidal drug for treating these infections. However, since 2002, vancomycin resistance has entered this species. Of the now 12 cases of vancomycin-resistantS. aureus(VRSA), each was believed to represent a new acquisition of the vancomycin-resistant transposon Tn1546from enterococcal donors. All acquisitions of Tn1546so far have occurred in MRSA strains of the clonal cluster 5 genetic background, the most common hospital lineage causing hospital-acquired MRSA infection. To understand the nature of these strains, we determined and examined the nucleotide sequences of the genomes of all available VRSA. Genome comparison identified candidate features that position strains of this lineage well for acquiring resistance to antibiotics in mixed infection.

scholarly journals Draft Genome Sequences of 14 Livestock-Associated Methicillin-Resistant Staphylococcus aureus Sequence Type 398 Isolates from Swine Farms in the United States

2017 ◽  
Vol 5 (44) ◽  
Author(s):  
Samantha J. Hau ◽  
Darrell O. Bayles ◽  
David P. Alt ◽  
Timothy S. Frana ◽  
Tracy L. Nicholson
Keyword(s):  
United States ◽  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Draft Genome ◽  
The United States ◽  
Sequence Type ◽  
Genome Sequences ◽  
Methicillin Resistant ◽  
Content Type ◽  
Mrsa St398

ABSTRACT Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is a bacterium carried by or obtained from swine and other livestock. The initial and predominant swine-associated LA-MRSA sequence type (ST) identified is ST398. Here, we present 14 draft genome sequences from LA-MRSA ST398 isolates found in the United States.

scholarly journals TelavancinIn VitroActivity against a Collection of Methicillin-Resistant Staphylococcus aureus Isolates, Including Resistant Subsets, from the United States

2015 ◽  
Vol 59 (3) ◽  
pp. 1811-1814 ◽  
Author(s):  
Rodrigo E. Mendes ◽  
Helio S. Sader ◽  
Robert K. Flamm ◽  
David J. Farrell ◽  
Ronald N. Jones
Keyword(s):  
United States ◽  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
The United States ◽  
Multidrug Resistant ◽  
Methicillin Resistant ◽  
Content Type

ABSTRACTTelavancin had MIC50, MIC90, and MIC100values of 0.03, 0.06, and 0.12 μg/ml, respectively, against methicillin-susceptibleStaphylococcus aureus, methicillin-resistantS. aureus(MRSA), and non-multidrug-resistant (non-MDR) and MDR subsets. MRSA with elevated MIC values for vancomycin (2 to 4 μg/ml) or daptomycin (1 to 2 μg/ml) had telavancin MIC50(0.06 μg/ml) values 2-fold higher than those of isolates with lower MIC results (MIC50, 0.03 μg/ml). However, telavancin had MIC90and MIC100results of 0.06 and 0.12 μg/ml (100% susceptible), respectively, regardless of the MRSA subset.

scholarly journals Draft Genome Sequences of 63 Swine-Associated Methicillin-Resistant Staphylococcus aureus Sequence Type 5 Isolates from the United States

2017 ◽  
Vol 5 (44) ◽  
Author(s):  
Samantha J. Hau ◽  
Darrell O. Bayles ◽  
David P. Alt ◽  
Timothy S. Frana ◽  
Tracy L. Nicholson
Keyword(s):  
United States ◽  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Draft Genome ◽  
The United States ◽  
Sequence Type ◽  
Public Concern ◽  
Genome Sequences ◽  
Methicillin Resistant ◽  
Content Type

ABSTRACT Methicillin-resistant Staphylococcus aureus colonizes humans and other animals such as swine. Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) sequence type 5 (ST5) isolates are a public concern due to their pathogenicity and ability to acquire mobile genetic elements. This report presents draft genome sequences for 63 LA-MRSA ST5 isolates in the United States.

scholarly journals Complete Genome Sequence of Livestock-Associated Methicillin-Resistant Staphylococcus aureus Sequence Type 398 Isolated from Swine in the United States

2017 ◽  
Vol 5 (32) ◽  
Author(s):  
Samantha J. Hau ◽  
Darrell O. Bayles ◽  
David P. Alt ◽  
Timothy S. Frana ◽  
Tracy L. Nicholson
Keyword(s):  
United States ◽  
Staphylococcus Aureus ◽  
Genome Sequence ◽  
Complete Genome Sequence ◽  
Complete Genome ◽  
The United States ◽  
Sequence Type ◽  
Methicillin Resistant ◽  
Content Type ◽  
Mrsa St398

ABSTRACT Methicillin-resistant Staphylococcus aureus (MRSA) colonizes and causes disease in many animal species. Livestock-associated MRSA (LA-MRSA) isolates are represented by isolates of the sequence type 398 (ST398). These isolates are considered to be livestock adapted. This report provides the complete genome sequence of one swine-associated LA-MRSA ST398 isolate from the United States.

scholarly journals Complete Genome Sequence of a Livestock-Associated Methicillin-Resistant Staphylococcus aureus Sequence Type 5 Isolate from the United States

2017 ◽  
Vol 5 (32) ◽  
Author(s):  
Samantha J. Hau ◽  
Darrell O. Bayles ◽  
David P. Alt ◽  
Timothy S. Frana ◽  
Tracy L. Nicholson
Keyword(s):  
United States ◽  
Staphylococcus Aureus ◽  
Genome Sequence ◽  
Complete Genome Sequence ◽  
Complete Genome ◽  
Hospital Setting ◽  
The United States ◽  
Sequence Type ◽  
Methicillin Resistant ◽  
Content Type

ABSTRACT Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) may be the largest MRSA reservoir outside the hospital setting. One concern with LA-MRSA is the acquisition of novel mobile genetic elements by these isolates. Here, we report the complete genome sequence of a swine LA-MRSA sequence type 5 isolate from the United States.

scholarly journals Oxacillin Alters the Toxin Expression Profile of Community-Associated Methicillin-Resistant Staphylococcus aureus

2013 ◽  
Vol 58 (2) ◽  
pp. 1100-1107 ◽  
Author(s):  
Justine K. Rudkin ◽  
Maisem Laabei ◽  
Andrew M. Edwards ◽  
Hwang-Soo Joo ◽  
Michael Otto ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Types ◽  
Pleiotropic Effect ◽  
Lytic Activity ◽  
Alpha Toxin ◽  
Methicillin Resistant ◽  
Content Type ◽  
Expression Levels ◽  
Type Iv ◽  
High Level

ABSTRACTThe emergence of community-associated methicillin-resistantStaphylococcus aureus(CA-MRSA) is a growing cause for concern. These strains are more virulent than health care-associated MRSA (HA-MRSA) due to higher levels of toxin expression. In a previous study, we showed that the high-level expression of PBP2a, the alternative penicillin binding protein encoded by themecAgene on type II staphylococcal cassette chromosomemec(SCCmec) elements, reduced toxicity by interfering with the Agr quorum sensing system. This was not seen in strains carrying the CA-MRSA-associated type IV SCCmecelement. These strains express significantly lower levels of PBP2a than the other MRSA type, which may explain their relatively high toxicity. We hypothesized that as oxacillin is known to increasemecAexpression levels, it may be possible to attenuate the toxicity of CA-MRSA by using this antibiotic. Subinhibitory oxacillin concentrations induced PBP2a expression, repressed Agr activity, and, as a consequence, decreased phenol-soluble modulin (PSM) secretion by CA-MRSA strains. However, consistent with other studies, oxacillin also increased the expression levels of alpha-toxin and Panton-Valentine leucocidin (PVL). The net effect of these changes on the ability to lyse diverse cell types was tested, and we found that where the PSMs and alpha-toxin are important, oxacillin reduced overall lytic activity, but where PVL is important, it increased lytic activity, demonstrating the pleiotropic effect of oxacillin on toxin expression by CA-MRSA.

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