scholarly journals Disk Diffusion Testing for Detection of Methicillin-Resistant Staphylococci: Does Moxalactam Improve upon Cefoxitin?

2016 ◽  
Vol 54 (12) ◽  
pp. 2905-2909 ◽  
Author(s):  
Marie Bonjean ◽  
Elisabeth Hodille ◽  
Oana Dumitrescu ◽  
Céline Dupieux ◽  
Christina Nkoud Mongo ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Operating Characteristic ◽  
Methicillin Resistance ◽  
Inhibition Zone ◽  
Disk Diffusion ◽  
Large Collection ◽  
Coagulase Negative Staphylococci ◽  
Content Type ◽  
High Inoculum ◽  
Disk Diffusion Testing

Disk diffusion testing is widely used to detect methicillin resistance in staphylococci, and cefoxitin is currently considered the best marker formecA-mediated methicillin resistance. In low-inoculum diffusion testing (colony suspension at 106CFU/ml), the addition of moxalactam in combination with cefoxitin has been reported to improve on cefoxitin alone for the detection of methicillin-heteroresistant staphylococci. However, moxalactam is absent from EUCAST and CLSI guidelines, which use high-inoculum diffusion testing (colony suspension at 108CFU/ml), calling into question the potential interest of including moxalactam in their recommendations. The inhibition zone diameters of cefoxitin and moxalactam, alone and in combination, were evaluated for concordance withmecAandmecCpositivity in a large collection of clinicalStaphylococcusisolates (611Staphylococcus aureus,Staphylococcuslugdunensis, andStaphylococcus saprophyticusisolates and 307 coagulase-negative staphylococci other thanS. lugdunensisandS. saprophyticusisolates, of which 22% and 53% weremecA-positive, respectively) and in 25mecC-positiveS. aureusisolates using high-inoculum diffusion testing. Receiver operating characteristic, sensitivity, and specificity analyses indicated that the detection ofmecA- andmecC-positive and negative isolates did not improve with moxalactam, either alone or in combination with cefoxitin, compared to cefoxitin alone. These findings were similar in both theS. aureus/S. lugdunensis/S. saprophyticusgroup and in the coagulase-negative staphylococci group. Our results do not support the use of moxalactam as an additional marker of methicillin resistance when testing with high-inoculum disk diffusion.

scholarly journals Novel Type XII Staphylococcal Cassette ChromosomemecHarboring a New Cassette Chromosome Recombinase, CcrC2

2015 ◽  
Vol 59 (12) ◽  
pp. 7597-7601 ◽  
Author(s):  
Zhaowei Wu ◽  
Fan Li ◽  
Dongliang Liu ◽  
Huping Xue ◽  
Xin Zhao
Keyword(s):  
United States ◽  
Staphylococcus Aureus ◽  
Methicillin Resistance ◽  
The United States ◽  
Gene Complex ◽  
Coagulase Negative Staphylococci ◽  
Typing Method ◽  
Content Type ◽  
Staphylococcal Cassette Chromosome ◽  
Sequence Identities

ABSTRACTExcision and integration of staphylococcal cassette chromosomemec(SCCmec) are mediated by cassette chromosome recombinases (Ccr), which play a crucial role in the worldwide spread of methicillin resistance in staphylococci. We report a novelccrgene,ccrC2, in the SCCmecof aStaphylococcus aureusisolate, BA01611, which showed 62.6% to 69.4% sequence identities to all publishedccrC1sequences. A further survey found that theccrC2gene was mainly located among coagulase-negative staphylococci (CoNS) and could be found in staphylococcal isolates from China, the United States, France, and Germany. Theccrgene complex harboring theccrC2gene was designated a type 9 complex, and the SCCmecof BA01611 was considered a novel type and was designated type XII (9C2). This novel SCCmecelement in BA01611 was flanked by a pseudo-SCC element (ΨSCCBA01611) carrying a truncatedccrA1gene. Both individual SCC elements and a composite SCC were excised from the chromosome based on detection of extrachromosomal circular intermediates. We advocate inclusion of the ccrC2gene and type 9ccrgene complex during revision of the SCCmectyping method.

scholarly journals Evaluation of cefoxitin disk diffusion breakpoint for detection of methicillin resistance in Staphylococcus pseudintermedius isolates from dogs

2012 ◽  
Vol 24 (5) ◽  
pp. 964-967 ◽  
Author(s):  
David A. Bemis ◽  
Rebekah D. Jones ◽  
Ricardo Videla ◽  
Stephen A. Kania
Keyword(s):  
Methicillin Resistance ◽  
Screening Method ◽  
Inhibition Zone ◽  
Disk Diffusion ◽  
Coagulase Negative Staphylococci ◽  
Staphylococcus Pseudintermedius ◽  
Growth Inhibition Zone ◽  
Disk Method ◽  
Cefoxitin Disk ◽  
Cefoxitin Disk Diffusion

Cefoxitin disk diffusion susceptibility testing is a recommended screening method for the detection of methicillin resistance in human isolates of Staphylococcus aureus and coagulase-negative staphylococci. A retrospective analysis of 1,146 clinical isolates of Staphylococcus pseudintermedius from dogs was conducted to determine if screening by the cefoxitin disk method can be similarly useful with S. pseudintermedius. The distribution of cefoxitin growth inhibition zone diameters within this collection was bimodal and correlated well with the results of methicillin resistance gene ( mecA) detection by polymerase chain reaction. Of the isolates, 5% had discordant results and, when retested, 84% of these were in agreement. While a greater diversity of isolates and interlaboratory comparisons must be tested, the current study suggests that an epidemiological breakpoint (of approximately ≤30 mm = resistant; ≥31 = susceptible) can be established to predict methicillin resistance in S. pseudintermedius.

scholarly journals Novel Multiplex PCR Assay for Detection of Chlorhexidine-Quaternary Ammonium, Mupirocin, and Methicillin Resistance Genes, with Simultaneous Discrimination of Staphylococcus aureus from Coagulase-Negative Staphylococci

2017 ◽  
Vol 55 (6) ◽  
pp. 1857-1864 ◽  
Author(s):  
Jo-Ann McClure ◽  
Johanna Zaal DeLongchamp ◽  
John M. Conly ◽  
Kunyan Zhang
Keyword(s):  
Staphylococcus Aureus ◽  
Multiplex Pcr ◽  
Resistance Genes ◽  
Quaternary Ammonium ◽  
Methicillin Resistance ◽  
Rrna Gene ◽  
Pcr Assay ◽  
Coagulase Negative Staphylococci ◽  
Content Type ◽  
Multiplex Pcr Assay

ABSTRACTMethicillin-resistantStaphylococcus aureus(MRSA) is a clinically significant pathogen that is resistant to a wide variety of antibiotics and responsible for a large number of nosocomial infections worldwide. The Agency for Healthcare Research and Quality and the Centers for Disease Control and Prevention recently recommended the adoption of universal mupirocin-chlorhexidine decolonization of all admitted intensive care unit patients rather than MRSA screening with targeted treatments, which raises a serious concern about the selection of resistance to mupirocin and chlorhexidine in strains of staphylococci. Thus, a simple, rapid, and reliable approach is paramount in monitoring the prevalence of resistance to these agents. We developed a simple multiplex PCR assay capable of screeningStaphylococcusisolates for the presence of antiseptic resistance genes for chlorhexidine and quaternary ammonium compounds, as well as mupirocin and methicillin resistance genes, while simultaneously discriminatingS. aureusfrom coagulase-negative staphylococci (CoNS). The assay incorporates 7 PCR targets, including theStaphylococcus16S rRNA gene (specifically detectingStaphylococcusspp.),nuc(distinguishingS. aureusfrom CoNS),mecA(distinguishing MRSA from methicillin-susceptibleS. aureus),mupAandmupB(identifying high-level mupirocin resistance), andqacandsmr(identifying chlorhexidine and quaternary ammonium resistance). Our assay demonstrated 100% sensitivity, specificity, and accuracy in a total of 23 variant antiseptic- and/or antibiotic-resistant control strains. Further validation of our assay using 378 randomly selected and previously well-characterized local clinical isolates confirmed its feasibility and practicality. This may prove to be a useful tool for multidrug-resistantStaphylococcusmonitoring in clinical laboratories, particularly in the wake of increased chlorhexidine and mupirocin treatments.

scholarly journals Evaluation of Oxacillin and Cefoxitin Disk Diffusion and MIC Breakpoints Established by the Clinical and Laboratory Standards Institute for Detection of mecA-Mediated Oxacillin Resistance in Staphylococcus schleiferi

2017 ◽  
Vol 56 (2) ◽  
Author(s):  
H. K. Huse ◽  
S. A. Miller ◽  
S. Chandrasekaran ◽  
J. A. Hindler ◽  
S. D. Lawhon ◽  
...  
Keyword(s):  
Opportunistic Infections ◽  
Performance Standards ◽  
Inhibition Zone ◽  
Disk Diffusion ◽  
Testing Methods ◽  
Coagulase Negative Staphylococci ◽  
Content Type ◽  
Oxacillin Resistance ◽  
Cefoxitin Disk ◽  
Cefoxitin Disk Diffusion

ABSTRACTStaphylococcus schleiferiis a beta-hemolytic, coagulase-variable colonizer of small animals that can cause opportunistic infections in humans. In veterinary isolates, the rate ofmecA-mediated oxacillin resistance is significant, with reported resistance rates of >39%. The goal of this study was to evaluate oxacillin and cefoxitin disk diffusion (DD) and MIC breakpoints for detection ofmecA-mediated oxacillin resistance in 52 human and 38 veterinary isolates ofS. schleiferi. Isolates were tested on multiple brands of commercial media and according to Clinical and Laboratory Standards Institute (CLSI) methods. Zone diameters and MIC values were interpreted using CLSI breakpoints (CLSI,Performance Standards for Antimicrobial Susceptibility Testing. M100-S27, 2017) forStaphylococcus aureus/Staphylococcus lugdunensis, coagulase-negative staphylococci (CoNS), andStaphylococcus pseudintermedius. Results were compared to those ofmecAPCR. Twenty-nine of 90 (32%) isolates weremecApositive. Oxacillin inhibition zone sizes and MICs interpreted byS. pseudintermediusbreakpoints reliably differentiatedmecA-positive andmecA-negative isolates, with a categorical agreement (CA) of 100% and no very major errors (VMEs) or major errors (MEs) for all media. For cefoxitin DD results interpreted usingS. aureus/S. lugdunensisand CoNS breakpoints, CA values were 85% and 75%, respectively, and there were 72% and 64% VMEs, respectively, and 0 MEs. For cefoxitin MICs interpreted usingS. aureus/S. lugdunensisbreakpoints, CA was 81%, and there were 60% VMEs and no MEs. Our data demonstrate that oxacillin DD or MIC testing methods using the currentS. pseudintermediusbreakpoints reliably identifymecA-mediated oxacillin resistance inS. schleiferi, while cefoxitin DD and MIC testing methods perform poorly.

scholarly journals Activity of Debio1452, a FabI Inhibitor with Potent Activity against Staphylococcus aureus and Coagulase-Negative Staphylococcus spp., Including Multidrug-Resistant Strains

2015 ◽  
Vol 59 (5) ◽  
pp. 2583-2587 ◽  
Author(s):  
Robert K. Flamm ◽  
Paul R. Rhomberg ◽  
Nachum Kaplan ◽  
Ronald N. Jones ◽  
David J. Farrell
Keyword(s):  
Staphylococcus Aureus ◽  
Antimicrobial Agents ◽  
Fatty Acid Biosynthesis ◽  
Multidrug Resistant ◽  
Coagulase Negative Staphylococcus ◽  
Significant Activity ◽  
Coagulase Negative Staphylococci ◽  
Content Type ◽  
Mrsa Strains ◽  
Human Infections

ABSTRACTStaphylococcus aureusand coagulase-negative staphylococci (CoNS) are responsible for a wide variety of human infections. The investigational antibacterial Debio1450 (previously AFN-1720), a prodrug of Debio1452 (previously AFN-1252), specifically targets staphylococci without significant activity against other Gram-positive or Gram-negative species. Debio1452 inhibits FabI, an enzyme critical to fatty acid biosynthesis in staphylococci. The activity of Debio1452 against CoNS, methicillin-susceptibleS. aureus(MSSA), and methicillin-resistantS. aureus(MRSA), including significant clones, was determined. A globally diverse collection of 574 patient isolates from 35 countries was tested that included CoNS (6 species, 103 strains), MSSA (154 strains), MRSA (163 strains), and molecularly characterized strains (includingspa-typed MRSA clones; 154 strains). The isolates were tested for susceptibility by CLSI broth microdilution methods against Debio1452 and 10 comparators. The susceptibility rates for the comparators were determined using CLSI and EUCAST breakpoint criteria. AllS. aureusand CoNS strains were inhibited by Debio1452 concentrations of ≤0.12 and ≤0.5 μg/ml, respectively. The MIC50s for MSSA, MRSA, and molecularly characterized MRSA strains were 0.004 μg/ml, and the MIC90s ranged from 0.008 to 0.03 μg/ml. The MICs were higher for the CoNS isolates (MIC50/90, 0.015/0.12 μg/ml). AmongS. aureusstrains, resistance was common for erythromycin (61.6%), levofloxacin (49.0%), clindamycin (27.6%), tetracycline (15.7%), and trimethoprim-sulfamethoxazole (7.0%). Debio1452 demonstrated potent activity against MSSA, MRSA, and CoNS. Debio1452 showed significantly greater activity overall (MIC50, 0.004 μg/ml) than the other agents tested against these staphylococcal species, which included dominant MRSA clones and strains resistant to currently utilized antimicrobial agents.

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