scholarly journals Five-Year Summary of In Vitro Activity and Resistance Mechanisms of Linezolid against Clinically Important Gram-Positive Cocci in the United States from the LEADER Surveillance Program (2011 to 2015)

2017 ◽  
Vol 61 (7) ◽  
Author(s):  
Michael A. Pfaller ◽  
Rodrigo E. Mendes ◽  
Jennifer M. Streit ◽  
Patricia A. Hogan ◽  
Robert K. Flamm
Keyword(s):  
United States ◽  
Staphylococcus Aureus ◽  
The United States ◽  
Resistance Mechanisms ◽  
23S Rrna ◽  
Rrna Gene ◽  
Gram Positive ◽  
Content Type ◽  
Linezolid Resistance

ABSTRACT This report describes linezolid susceptibility testing results for 6,741 Gram-positive pathogens from 60 U.S. sites collected during 2015 for the LEADER Program. In addition, the report summarizes linezolid in vitro activity, resistance mechanisms, and molecular typing obtained for 2011 to 2015. During 2015, linezolid showed potent activity in testing against Staphylococcus aureus, inhibiting >99.9% of 3,031 isolates at ≤2 µg/ml. Similarly, linezolid showed coverage against 99.2% of coagulase-negative staphylococci, 99.7% of enterococci, and 100.0% of Streptococcus pneumoniae, virdans group, and beta-hemolytic streptococcus isolates tested. The overall linezolid resistance rate remained a modest <1% from 2011 to 2015. Staphylococci, especially Staphylococcus epidermidis, showed a range of linezolid resistance mechanisms. Increased annual trends for the presence of cfr among Staphylococcus aureus isolates were not observed, but 64.3% (9/14) of the isolates with decreased susceptibility (MIC, ≥4 µg/ml) to linezolid carried this transferrable gene (2011 to 2015). The cfr gene was detected in 21.9% (7/32) of linezolid-resistant staphylococci other than S. aureus from 2011 to 2015. The optrA gene was noted in half (2/4) of the population of linezolid-nonsusceptible Enterococcus faecalis isolates from 2011 to 2015, while linezolid-nonsusceptible Enterococcus faecium isolates showed alterations predominantly (16/16) in the 23S rRNA gene (G2576T). This report confirms a long record of linezolid activity against Gram-positive isolates in the United States since regulatory approval in 2000 and reports the oxazolidinones evolving resistance mechanisms.

scholarly journals Summary of Linezolid Activity and Resistance Mechanisms Detected during the 2012 LEADER Surveillance Program for the United States

2013 ◽  
Vol 58 (2) ◽  
pp. 1243-1247 ◽  
Author(s):  
Rodrigo E. Mendes ◽  
Robert K. Flamm ◽  
Patricia A. Hogan ◽  
James E. Ross ◽  
Ronald N. Jones
Keyword(s):  
United States ◽  
Staphylococcus Aureus ◽  
Susceptibility Testing ◽  
The United States ◽  
Resistance Mechanisms ◽  
Regulatory Approval ◽  
Surveillance Program ◽  
Gram Positive ◽  
Content Type

ABSTRACTThis study summarizes the linezolid susceptibility testing results for 7,429 Gram-positive pathogens from 60 U.S. sites collected during the 2012 sampling year for the LEADER Program. Linezolid showed potent activity when tested against 2,980Staphylococcus aureusisolates, inhibiting all but 3 at ≤2 μg/ml. Similarly, linezolid showed coverage against 99.5% of enterococci, as well as for all streptococci tested. These results confirm a long record of linezolid activity against U.S. Gram-positive isolates since regulatory approval in 2000.

scholarly journals JNJ-Q2, a New Fluoroquinolone with PotentIn VitroActivity against Staphylococcus aureus, Including Methicillin- and Fluoroquinolone-Resistant Strains

2011 ◽  
Vol 55 (7) ◽  
pp. 3631-3634 ◽  
Author(s):  
David J. Farrell ◽  
Lisa C. Liverman ◽  
Douglas J. Biedenbach ◽  
Ronald N. Jones
Keyword(s):  
United States ◽  
Staphylococcus Aureus ◽  
Broad Spectrum ◽  
The United States ◽  
Gram Positive ◽  
Content Type ◽  
Skin Structure ◽  
Resistant Strains

ABSTRACTJNJ-Q2 is a broad-spectrum bactericidal fluoroquinolone with potent activity against Gram-positive and -negative pathogens. In this study, thein vitroactivity of JNJ-Q2 was evaluated against 511 selectedStaphylococcus aureussamples isolated in 2008-2009 from patients with acute bacterial skin and skin structure infections in the United States by using reference methodology. JNJ-Q2 was the most potent fluoroquinolone tested overall (MIC50and MIC90, 0.12 and 0.5 μg/ml, respectively) and against methicillin- and fluoroquinolone-resistant subgroups in direct comparisons to moxifloxacin, levofloxacin, and ciprofloxacin (each being ≥16-fold less potent than JNJ-Q2).

scholarly journals USA300 and USA500 Clonal Lineages of Staphylococcus aureus Do Not Produce a Capsular Polysaccharide Due to Conserved Mutations in the cap5 Locus

mBio ◽  
2015 ◽  
Vol 6 (2) ◽  
Author(s):  
Susan Boyle-Vavra ◽  
Xue Li ◽  
Md Tauqeer Alam ◽  
Timothy D. Read ◽  
Julia Sieth ◽  
...  
Keyword(s):  
United States ◽  
Staphylococcus Aureus ◽  
Capsular Polysaccharide ◽  
The United States ◽  
Whole Genome Sequence ◽  
Content Type ◽  
Capsule Production ◽  
Usa300 Strain

ABSTRACTThe surface capsular polysaccharide (CP) is a virulence factor that has been used as an antigen in several successful vaccines against bacterial pathogens. A vaccine has not yet been licensed againstStaphylococcus aureus, although two multicomponent vaccines that contain CP antigens are in clinical trials. In this study, we evaluated CP production in USA300 methicillin-resistantS. aureus(MRSA) isolates that have become the predominant community-associated MRSA clones in the United States. We found that all 167 USA300 MRSA and 50 USA300 methicillin-susceptibleS. aureus(MSSA) isolates were CP negative (CP−). Moreover, all 16 USA500 isolates, which have been postulated to be the progenitor lineage of USA300, were also CP−. Whole-genome sequence analysis of 146 CP−USA300 MRSA isolates revealed they all carry acap5locus with 4 conserved mutations compared with strain Newman. Genetic complementation experiments revealed that three of these mutations (in thecap5promoter,cap5Dnucleotide 994, andcap5Enucleotide 223) ablated CP production in USA300 and that Cap5E75 Asp, located in the coenzyme-binding domain, is essential for capsule production. All but three USA300 MSSA isolates had the same fourcap5mutations found in USA300 MRSA isolates. Most isolates with a USA500 pulsotype carried three of these four USA300-specific mutations, suggesting the fourth mutation occurred in the USA300 lineage. Phylogenetic analysis of thecaploci of our USA300 isolates as well as publicly available genomes from 41 other sequence types revealed that the USA300-specificcap5mutations arose sequentially inS. aureusin a common ancestor of USA300 and USA500 isolates.IMPORTANCEThe USA300 MRSA clone emerged as a community-associated pathogen in the United States nearly 20 years ago. Since then, it has rapidly disseminated and now causes health care-associated infections. This study shows that the CP-negative (CP−) phenotype has persisted among USA300 isolates and is a universal and characteristic trait of this highly successful MRSA lineage. It is important to note that a vaccine consisting solely of CP antigens would not likely demonstrate high efficacy in the U.S. population, where about half of MRSA isolates comprise USA300. Moreover, conversion of a USA300 strain to a CP-positive (CP+) phenotype is unlikelyin vivoorin vitrosince it would require the reversion of 3 mutations. We have also established that USA300 MSSA isolates and USA500 isolates are CP−and provide new insight into the evolution of the USA300 and USA500 lineages.

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 LEADER Program Results for 2009: an Activity and Spectrum Analysis of Linezolid Using 6,414 Clinical Isolates from 56 Medical Centers in the United States

2011 ◽  
Vol 55 (8) ◽  
pp. 3684-3690 ◽  
Author(s):  
David J. Farrell ◽  
Rodrigo E. Mendes ◽  
James E. Ross ◽  
Helio S. Sader ◽  
Ronald N. Jones
Keyword(s):  
United States ◽  
Geographic Area ◽  
The United States ◽  
Multidrug Resistant ◽  
23S Rrna ◽  
Coagulase Negative Staphylococci ◽  
Laboratory Design ◽  
Linezolid Resistance ◽  
Medical Centers

ABSTRACTThe LEADER Program monitors thein vitroactivity of linezolid in sampled U.S. medical centers using reference broth microdilution methods with supporting molecular investigations in a central laboratory design. This report summarizes data obtained in 2009, the 6th consecutive year of this longitudinal study. A total of 6,414 isolates from 56 medical centers in all nine Census regions across the United States participated in 2009. For the six leading species/groups, the following linezolid MIC90values were observed:Staphylococcus aureus, 2 μg/ml; coagulase-negative staphylococci (CoNS), 1 μg/ml;Enterococcusspp., 2 μg/ml;Streptococcus pneumoniae, 1 μg/ml; viridans group streptococci, 1 μg/ml; and beta-hemolytic streptococci, 1 μg/ml. Linezolid resistance was only 0.34% overall, with no evidence of significant increase in the LEADER Program since 2006. The predominant linezolid resistant mechanism found was a G2576T mutation in the 23S rRNA. L3/L4 riboprotein mutations were also found. The mobile multidrug-resistantcfrgene was found in four strains (twoS. aureusstrains and one strain each ofS. epidermidisandS. capitis) from four different states, suggesting persistence but a lack of dissemination. Linezolid continues to exhibit excellent activity and spectrum, and this study documents the need for continued monitoring of emerging mechanisms of resistance over a wide geographic area.

scholarly journals Genetic Diversity and Geographical Distribution of Indigenous Soybean-Nodulating Bradyrhizobia in the United States

2013 ◽  
Vol 79 (12) ◽  
pp. 3610-3618 ◽  
Author(s):  
Sokichi Shiro ◽  
Syota Matsuura ◽  
Rina Saiki ◽  
Gilbert C. Sigua ◽  
Akihiro Yamamoto ◽  
...  
Keyword(s):  
United States ◽  
Genetic Diversity ◽  
Community Structure ◽  
Geographical Distribution ◽  
The United States ◽  
23S Rrna ◽  
Rrna Gene ◽  
Scaling Analysis ◽  
Internal Transcribed Spacer Region ◽  
Content Type

ABSTRACTWe investigated the relationship between the genetic diversity of indigenous soybean-nodulating bradyrhizobia and their geographical distribution in the United States using nine soil isolates from eight states. The bradyrhizobia were inoculated on three soybeanRjgenotypes (non-Rj,Rj2Rj3, andRj4). We analyzed their genetic diversity and community structure by means of restriction fragment length polymorphisms of PCR amplicons to target the 16S-23S rRNA gene internal transcribed spacer region, using 11 USDABradyrhizobiumstrains as reference strains. We also performed diversity analysis, multidimensional scaling analysis based on the Bray-Curtis index, and polar ordination analysis to describe the structure and geographical distribution of the soybean-nodulating bradyrhizobial community. The major clusters wereBradyrhizobium japonicumBj123, in the northern United States, andBradyrhizobium elkanii, in the middle to southern regions. Dominance of bradyrhizobia in a community was generally larger for the cluster belonging toB. elkaniithan for the cluster belonging toB. japonicum. The indigenous American soybean-nodulating bradyrhizobial community structure was strongly correlated with latitude. Our results suggest that this community varies geographically.

scholarly journals Potency and Bactericidal Activity of Iclaprim against Recent Clinical Gram-Positive Isolates

2009 ◽  
Vol 53 (5) ◽  
pp. 2171-2175 ◽  
Author(s):  
Helio S. Sader ◽  
Thomas R. Fritsche ◽  
Ronald N. Jones
Keyword(s):  
United States ◽  
Staphylococcus Aureus ◽  
Enterococcus Faecalis ◽  
Bactericidal Activity ◽  
The United States ◽  
Vitro Activity ◽  
In Vitro Activity ◽  
Gram Positive ◽  
Methicillin Resistant

ABSTRACT The in vitro activity of iclaprim, a novel diaminopyrimidine derivative, was evaluated against 5,937 recent gram-positive clinical isolates collected in the United States and Europe. Iclaprim demonstrated potent activity against Staphylococcus aureus (including methicillin-resistant S. aureus [MRSA]), beta-hemolytic Streptococcus spp., and Enterococcus faecalis strains tested. In addition, iclaprim exhibited bactericidal activity against all S. aureus strains tested, including MRSA.

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 Worldwide Appraisal and Update (2010) of Telavancin Activity Tested against a Collection of Gram-Positive Clinical Pathogens from Five Continents

2012 ◽  
Vol 56 (7) ◽  
pp. 3999-4004 ◽  
Author(s):  
Rodrigo E. Mendes ◽  
Helio S. Sader ◽  
David J. Farrell ◽  
Ronald N. Jones
Keyword(s):  
Staphylococcus Aureus ◽  
The United States ◽  
Asia Pacific ◽  
Pacific Region ◽  
Asia Pacific Region ◽  
Gram Positive ◽  
Content Type ◽  
Viridans Group Streptococcus ◽  
Clinical Pathogens

ABSTRACTA total of 15,480 Gram-positive pathogens were collected from 89 sites in the United States, Europe, the Asia-Pacific region, and Latin America in 2010. Telavancin was active against indicatedStaphylococcus aureus(MIC50/90, 0.12/0.25 μg/ml), vancomycin-susceptibleEnterococcus faecalis(MIC50/90, 0.5/0.5 μg/ml), and beta-hemolytic (MIC50/90, 0.06/0.12 μg/ml) and viridans group streptococcus (MIC50/90, 0.03/0.06 μg/ml) isolates. These MIC results showed potency for telavancin equal to or greater than that of comparators. Thesein vitrodata confirm a continued potent activity of telavancin when tested against contemporary Gram-positive clinical isolates.

Sign in / Sign up

Export Citation Format

Share Document