scholarly journals Antimicrobial Susceptibility of Pseudomonas aeruginosa to Ceftazidime-Avibactam, Ceftolozane-Tazobactam, Piperacillin-Tazobactam, and Meropenem Stratified by U.S. Census Divisions: Results from the 2017 INFORM Program

2018 ◽  
Vol 62 (12) ◽  
Author(s):  
Helio S. Sader ◽  
Robert K. Flamm ◽  
Cecilia G. Carvalhaes ◽  
Mariana Castanheira
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antimicrobial Susceptibility ◽  
Broth Microdilution ◽  
Content Type ◽  
Microdilution Method ◽  
Medical Centers ◽  
Broth Microdilution Method

ABSTRACT Pseudomonas aeruginosa isolates (n = 1,909) were collected from 70 U.S. medical centers, and their susceptibilities were tested using the broth microdilution method. Ceftazidime-avibactam (MIC50/MIC90, 2/8 mg/liter) and ceftolozane-tazobactam (MIC50/MIC90, 0.5/2 mg/liter) were the most active (i.e., had the highest susceptibility rates) compounds after colistin, with national susceptibility rates of 96.9% and 97.5%, respectively. Overall, piperacillin-tazobactam (MIC50/MIC90, 4/128 mg/liter) and meropenem (MIC50/MIC90, 0.5/16 mg/liter) were active against 77.5% and 76.0% of the isolates, respectively. Susceptibility variations across census divisions were documented for many antimicrobials.

scholarly journals Antimicrobial Activity of Murepavadin Tested against Clinical Isolates of Pseudomonas aeruginosa from the United States, Europe, and China

2018 ◽  
Vol 62 (7) ◽  
Author(s):  
Helio S. Sader ◽  
Glenn E. Dale ◽  
Paul R. Rhomberg ◽  
Robert K. Flamm
Keyword(s):  
United States ◽  
Pseudomonas Aeruginosa ◽  
Cyclic Peptide ◽  
Polymyxin B ◽  
The United States ◽  
Broth Microdilution ◽  
Content Type ◽  
Microdilution Method ◽  
Medical Centers ◽  
Broth Microdilution Method

ABSTRACT Murepavadin (formerly POL7080), a 14-amino-acid cyclic peptide, and comparators were tested by the broth microdilution method against 1,219 Pseudomonas aeruginosa isolates from 112 medical centers. Murepavadin (MIC 50/90 , 0.12/0.12 mg/liter) was 4- to 8-fold more active than colistin (MIC 50/90 , 1/1 mg/liter) and polymyxin B (MIC 50/90 , 0.5/1 mg/liter) and inhibited 99.1% of isolates at ≤0.5 mg/liter. Only 4 isolates (0.3%) exhibited murepavadin MICs of >2 mg/liter. Murepavadin was equally active against isolates from Europe, the United States, and China.

scholarly journals Ceftazidime-Avibactam Activity against Multidrug-Resistant Pseudomonas aeruginosa Isolated in U.S. Medical Centers in 2012 and 2013

2015 ◽  
Vol 59 (6) ◽  
pp. 3656-3659 ◽  
Author(s):  
Helio S. Sader ◽  
Mariana Castanheira ◽  
Rodrigo E. Mendes ◽  
Robert K. Flamm ◽  
David J. Farrell ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Multidrug Resistant ◽  
Drug Resistant ◽  
Broth Microdilution ◽  
Content Type ◽  
Microdilution Method ◽  
Medical Centers ◽  
Extensively Drug Resistant ◽  
Broth Microdilution Method

ABSTRACTPseudomonas aeruginosaisolates (n= 3,902) from 75 U.S. medical centers were tested against ceftazidime-avibactam and comparator agents by the reference broth microdilution method. Overall, 96.9% of the strains were susceptible (MIC, ≤8 μg/ml) to ceftazidime-avibactam, while the rates of susceptibility for ceftazidime, meropenem, and piperacillin-tazobactam were 83.8, 81.9, and 78.5%, respectively. Multidrug-resistant and extensively drug-resistant phenotypes were observed in 14.9 and 8.7% of the strains, respectively, and 81.0 and 73.7% of the strains were susceptible to ceftazidime-avibactam, respectively.

scholarly journals Antimicrobial Activity of Ceftolozane-Tazobactam Tested against Enterobacteriaceae and Pseudomonas aeruginosa with Various Resistance Patterns Isolated in U.S. Hospitals (2011-2012)

2013 ◽  
Vol 57 (12) ◽  
pp. 6305-6310 ◽  
Author(s):  
David J. Farrell ◽  
Robert K. Flamm ◽  
Helio S. Sader ◽  
Ronald N. Jones
Keyword(s):  
Pseudomonas Aeruginosa ◽  
The United States ◽  
Multidrug Resistant ◽  
High Rate ◽  
Drug Resistant ◽  
Good Activity ◽  
Content Type ◽  
Microdilution Method ◽  
Medical Centers ◽  
Broth Microdilution Method

ABSTRACTCeftolozane/tazobactam, a novel antimicrobial agent with activity againstPseudomonas aeruginosa(including drug-resistant strains) and other common Gram-negative pathogens (including most extended-spectrum-β-lactamase [ESBL]-producingEnterobacteriaceaestrains), and comparator agents were susceptibility tested by a reference broth microdilution method against 7,071Enterobacteriaceaeand 1,971P. aeruginosaisolates. Isolates were collected consecutively from patients in 32 medical centers across the United States during 2011 to 2012. Overall, 15.7% and 8.9% ofP. aeruginosaisolates were classified as multidrug resistant (MDR) and extensively drug resistant (XDR), and 8.4% and 1.2% ofEnterobacteriaceaewere classified as MDR and XDR. No pandrug-resistant (PDR)Enterobacteriaceaeisolates and only one PDRP. aeruginosaisolate were detected. Ceftolozane/tazobactam was the most potent (MIC50/90, 0.5/2 μg/ml) agent tested againstP. aeruginosaand demonstrated good activity against 310 MDR strains (MIC50/90, 2/8 μg/ml) and 175 XDR strains (MIC50/90, 4/16 μg/ml). Ceftolozane/tazobactam exhibited high overall activity (MIC50/90, 0.25/1 μg/ml) againstEnterobacteriaceaeand retained activity (MIC50/90, 4/>32 μg/ml) against many 601 MDR strains but not against the 86 XDR strains (MIC50, >32 μg/ml). Ceftolozane/tazobactam was highly potent (MIC50/90, 0.25/0.5 μg/ml) against 2,691Escherichia coliisolates and retained good activity against most ESBL-phenotypeE. coliisolates (MIC50/90, 0.5/4 μg/ml), but activity was low against ESBL-phenotypeKlebsiella pneumoniaeisolates (MIC50/90, 32/>32 μg/ml), explained by the high rate (39.8%) of meropenem coresistance observed in this species phenotype. In summary, ceftolozane/tazobactam demonstrated high potency and broad-spectrum activity against many contemporaryEnterobacteriaceaeandP. aeruginosaisolates collected in U.S. medical centers. Importantly, ceftolozane/tazobactam retained potency against many MDR and XDR strains.

scholarly journals Comparative activity of newer β-lactam/β-lactamase inhibitor combinations against Pseudomonas aeruginosa from patients hospitalized with pneumonia in European medical centers in 2020

2021 ◽  
Author(s):  
Helio S. Sader ◽  
Cecilia G. Carvalhaes ◽  
Dee Shortridge ◽  
Mariana Castanheira
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Eastern Europe ◽  
Western Europe ◽  
Broth Microdilution ◽  
Active Compounds ◽  
Microdilution Method ◽  
Medical Centers ◽  
Broth Microdilution Method ◽  
Lactamase Inhibitor ◽  
Comparative Activity

Abstract Pseudomonas aeruginosa isolates were consecutively collected from patients with pneumonia in 29 medical centers in 2020 and susceptibility tested by broth microdilution method. Ceftazidime-avibactam (95.5% susceptible), imipenem-relebactam (94.3% susceptible), and ceftolozane-tazobactam (93.3% susceptible) were the most active compounds after colistin (99.5% susceptible). Susceptibility rates for the β-lactam/β-lactamase inhibitor combinations (BL/BLIs) varied against isolates resistant to piperacillin-tazobactam, meropenem, imipenem, and/or ceftazidime. Ceftazidime-avibactam was the most active BL/BLI against resistant subsets from Western Europe, whereas imipenem-relebactam was slightly more active than other BL/BLIs against resistant subsets from Eastern Europe. Susceptibility rates were markedly lower in Eastern Europe than Western Europe.

scholarly journals Antimicrobial Activity of Ceftaroline-Avibactam Tested against Clinical Isolates Collected from U.S. Medical Centers in 2010-2011

2013 ◽  
Vol 57 (4) ◽  
pp. 1982-1988 ◽  
Author(s):  
Helio S. Sader ◽  
Robert K. Flamm ◽  
Ronald N. Jones
Keyword(s):  
Staphylococcus Aureus ◽  
Antimicrobial Activity ◽  
Streptococcus Pneumoniae ◽  
Enterobacter Cloacae ◽  
Broth Microdilution ◽  
Methicillin Resistant ◽  
Content Type ◽  
Microdilution Method ◽  
Medical Centers ◽  
Broth Microdilution Method

ABSTRACTCeftaroline-avibactam and comparator agents were tested by the broth microdilution method against 20,089 isolates consecutively collected in 2010 and 2011 from 75 U.S. medical centers. Ceftaroline-avibactam was active againstEnterobacteriaceae(4,908 strains; MIC90, 0.25 μg/ml; highest MIC, 4 μg/ml), including meropenem-nonsusceptibleKlebsiellaspp. and ceftazidime-nonsusceptibleEnterobacter cloacaestrains (MIC90, 1 μg/ml for both). Ceftaroline-avibactam was also active against ceftriaxone-nonsusceptibleStreptococcus pneumoniae(MIC90, 0.25 μg/ml) and methicillin-resistantStaphylococcus aureus(MIC90, 1 μg/ml).

scholarly journals Activity of Ceftazidime-Avibactam against Fluoroquinolone-Resistant Enterobacteriaceae and Pseudomonas aeruginosa

2015 ◽  
Vol 59 (6) ◽  
pp. 3059-3065 ◽  
Author(s):  
C. Pitart ◽  
F. Marco ◽  
T. A. Keating ◽  
W. W. Nichols ◽  
J. Vila
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Resistant Mutant ◽  
Fluoroquinolone Resistance ◽  
Cross Resistance ◽  
Content Type ◽  
E Coli ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
The Impact

ABSTRACTCeftazidime-avibactam and comparator antibiotics were tested by the broth microdilution method against 200Enterobacteriaceaeand 25Pseudomonas aeruginosastrains resistant to fluoroquinolones (including strains with the extended-spectrum β-lactamase [ESBL] phenotype and ceftazidime-resistant strains) collected from our institution. The MICs and mechanisms of resistance to fluoroquinolone were also studied. Ninety-nine percent of fluoroquinolone-resistantEnterobacteriaceaestrains were inhibited at a ceftazidime-avibactam MIC of ≤4 mg/liter (using the susceptible CLSI breakpoint for ceftazidime alone as a reference). Ceftazidime-avibactam was very active against ESBLEscherichia coli(MIC90of 0.25 mg/liter), ESBLKlebsiella pneumoniae(MIC90of 0.5 mg/liter), ceftazidime-resistant AmpC-producing species (MIC90of 1 mg/liter), non-ESBLE. coli(MIC90of ≤0.125 mg/liter), non-ESBLK. pneumoniae(MIC90of 0.25 mg/liter), and ceftazidime-nonresistant AmpC-producing species (MIC90of ≤0.5 mg/liter). Ninety-six percent of fluoroquinolone-resistantP. aeruginosastrains were inhibited at a ceftazidime-avibactam MIC of ≤8 mg/liter (using the susceptible CLSI breakpoint for ceftazidime alone as a reference), with a MIC90of 8 mg/liter. Additionally, fluoroquinolone-resistant mutants from each species tested were obtainedin vitrofrom two strains, one susceptible to ceftazidime and the other a β-lactamase producer with a high MIC against ceftazidime but susceptible to ceftazidime-avibactam. Thereby, the impact of fluoroquinolone resistance on the activity of ceftazidime-avibactam could be assessed. The MIC90values of ceftazidime-avibactam for the fluoroquinolone-resistant mutant strains ofEnterobacteriaceaeandP. aeruginosawere ≤4 mg/liter and ≤8 mg/liter, respectively. We conclude that the presence of fluoroquinolone resistance does not affectEnterobacteriaceaeandP. aeruginosasusceptibility to ceftazidime-avibactam; that is, there is no cross-resistance.

scholarly journals Antifungal Susceptibility Testing of Malassezia spp. with an Optimized Colorimetric Broth Microdilution Method

2017 ◽  
Vol 55 (6) ◽  
pp. 1883-1893 ◽  
Author(s):  
Cheryl Leong ◽  
Antonino Buttafuoco ◽  
Martin Glatz ◽  
Philipp P. Bosshard
Keyword(s):  
Susceptibility Testing ◽  
Skin Diseases ◽  
Antifungal Susceptibility ◽  
Drug Susceptibility ◽  
Drug Susceptibility Testing ◽  
Broth Microdilution ◽  
Content Type ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Colorimetric Indicator

ABSTRACTMalasseziais a genus of lipid-dependent yeasts. It is associated with common skin diseases such as pityriasis versicolor and atopic dermatitis and can cause systemic infections in immunocompromised individuals. Owing to the slow growth and lipid requirements of these fastidious yeasts, convenient and reliable antifungal drug susceptibility testing assays forMalasseziaspp. are not widely available. Therefore, we optimized a broth microdilution assay for the testing ofMalasseziathat is based on the CLSI and EUCAST assays forCandidaand other yeasts. The addition of ingredients such as lipids and esculin provided a broth medium formulation that enabled the growth of allMalasseziaspp. and could be read, with the colorimetric indicator resazurin, by visual and fluorescence readings. We tested the susceptibility of 52 strains of 13Malasseziaspecies to 11 commonly used antifungals. MIC values determined by visual readings were in good agreement with MIC values determined by fluorescence readings. The lowest MICs were found for the azoles itraconazole, posaconazole, and voriconazole, with MIC90values of 0.03 to 1.0 μg/ml, 0.06 to 0.5 μg/ml, and 0.03 to 2.0 μg/ml, respectively. AllMalasseziaspp. were resistant to echinocandins and griseofulvin. SomeMalasseziaspp. also showed high MIC values for ketoconazole, which is the most widely recommended topical antifungal to treatMalasseziaskin infections. In summary, our assay enables the fast and reliable susceptibility testing ofMalasseziaspp. with a large panel of different antifungals.

scholarly journals Prevalence of a Cefazolin Inoculum Effect Associated withblaZGene Types among Methicillin-SusceptibleStaphylococcus aureusIsolates from Four Major Medical Centers in Chicago

2018 ◽  
Vol 62 (8) ◽  
Author(s):  
Sheila K. Wang ◽  
Annette Gilchrist ◽  
Anastasia Loukitcheva ◽  
Balbina J. Plotkin ◽  
Ira M. Sigar ◽  
...  
Keyword(s):  
Fold Increase ◽  
Type A ◽  
Content Type ◽  
Microdilution Method ◽  
Medical Centers ◽  
High Inoculum ◽  
Gene Type ◽  
Broth Microdilution Method ◽  
Type C ◽  
Inoculum Effect

ABSTRACTThe efficacy of cefazolin with high-inoculum methicillin-susceptibleStaphylococcus aureus(MSSA) infections remains in question due to therapeutic failure inferred as being due to an inoculum effect (InE). This study investigated the local prevalence of a cefazolin InE (CInE) and its association with staphylococcalblaZgene types among MSSA isolates in the Chicago area. Four medical centers in Chicago, IL, contributed MSSA isolates. Cefazolin MICs (C-MIC) were determined at 24 h by the broth microdilution method using a standard inoculum (SI; 5 × 105CFU/ml) and a high inoculum (HI; 5 × 107CFU/ml). The CInE was defined as (i) a ≥4-fold increase in C-MIC between SI and HI and/or (ii) a pronounced CInE, i.e., a nonsusceptible C-MIC of ≥16 μg/ml at HI. PCR was used to amplify theblaZgene, followed by agarose gel electrophoresis and sequencing to determine the gene type. Approximately 269 MSSA isolates were included. All but one isolate were susceptible to cefazolin at SI, and 97% remained susceptible at HI. A total of 196 isolates (73%) wereblaZpositive, with theblaZtypes led by gene type C (40%). CInE was seen in 45blaZ-positive isolates (23%), with 44 (22%) presenting a ≥4-fold increase in C-MIC (SI to HI) and 5 (3%) a pronounced CInE. Four of the five met both definitions of CInE, two of which expressed the type A gene. The prevalence of a pronounced CInE associated with the type AblaZgene from MSSA isolates in Chicago is low. Our predilection for cefazolin use, even early in the management of hospitalized MSSA infections, is tenable.

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