scholarly journals Evaluation of Clinical Laboratory Standards Institute Interpretive Criteria for Methicillin-Resistant Staphylococcus Pseudintermedius Isolated from Dogs

2009 ◽  
Vol 21 (5) ◽  
pp. 684-688 ◽  
Author(s):  
Jennifer R. Schissler ◽  
Andrew Hillier ◽  
Joshua B. Daniels ◽  
Lynette K. Cole ◽  
Wondwossen A. Gebreyes
Keyword(s):  
Methicillin Resistance ◽  
False Negative ◽  
Meca Gene ◽  
Diagnostic Sensitivity ◽  
Disk Diffusion ◽  
Staphylococcus Pseudintermedius ◽  
Methicillin Resistant ◽  
Interpretive Criterion ◽  
Cefoxitin Disk ◽  
Cefoxitin Disk Diffusion

The Clinical and Laboratory Standards Institute published in 2008 new interpretive criteria for the identification of methicillin resistance in staphylococci isolated from animals. The sensitivity of the 2008 interpretive criteria for mecA gene-positive Staphylococcus pseudintermedius, compared with the previous criteria of 2004, was investigated. Thirty clinical isolates of methicillin-resistant S. pseudintermedius from dogs were used. The presence of the mecA gene was determined by polymerase chain reaction. The minimum inhibitory concentration for oxacillin was determined by broth microdilution. The 2008 breakpoint of 4 μg/ml for methicillin resistance resulted in a diagnostic sensitivity of 73.3% (22/30). The 2004 breakpoint guideline of 0.5 μg/ml resulted in a diagnostic sensitivity of 97% (29/30). For oxacillin disk diffusion, the 2008 interpretive criterion of 10 mm for methicillin resistance resulted in a sensitivity of 70% (21/30). If intermediate isolates (11 or 12 mm) were considered resistant, the sensitivity was 93% (28/30). Application of the 2004 interpretive criterion of 17 mm resulted in a diagnostic sensitivity of 100% (30/30). For cefoxitin disk diffusion, the interpretive criterion of 21 mm for methicillin resistance (as used for Staphylococcus aureus) resulted in a diagnostic sensitivity of 6.7% (2/30). The interpretive criterion of 24 mm (as used for coagulase-negative staphylococci) resulted in a diagnostic sensitivity of 43.3% (13/30). With the use of 2008 interpretive criteria, all 3 tests produced what we consider to be an unacceptable level of false negative results. Our findings also suggest that cefoxitin disk diffusion is an inappropriate screening test for methicillin resistance of canine S. pseudintermedius.

scholarly journals Ceftaroline resistance in Staphylococcus pseudintermedius gene mecA carriers

2018 ◽  
Vol 38 (12) ◽  
pp. 2233-2236
Author(s):  
Carolina B. Scherer ◽  
Larissa S. Botoni ◽  
Antônio U. Carvalho ◽  
Kelly M. Keller ◽  
Adriane P. Costa-Val
Keyword(s):  
Methicillin Resistance ◽  
Meca Gene ◽  
Disk Diffusion ◽  
Diffusion Test ◽  
Staphylococcus Pseudintermedius ◽  
Ceftaroline Fosamil ◽  
Disk Diffusion Test ◽  
Methicillin Resistant ◽  
Resistant Strains ◽  
Current Report

ABSTRACT: Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) being a constant concern, ceftaroline fosamil has been recently approved as a new cephalosporin, active against MRSA, for use in humans; only rare cases of resistance have been reported till date. There is no report of resistance to ceftaroline in Staphylococcus pseudintermedius, which is the main bacterium causing dermatitis and otitis in dogs. To evaluate staphylococcal resistance to ceftaroline, 35 isolates of methicillin-resistant S. pseudintermedius (MRSP), carrying the mecA gene, from 26 dogs with folliculitis and nine dogs with external otitis, underwent disk diffusion test with cefoxitin, oxacillin, and ceftaroline. Tests with cefoxitin and oxacillin showed > 90% sensitivity in methicillin resistance detection. In the disk diffusion test, 97.14% (34/35) were resistant to cefoxitin, 94.29% (33/35) to oxacillin, and 31.43% (11/35) to ceftaroline. Of the ceftaroline-resistant strains, 27.27% (3/11) were obtained from the ears of dogs while the rest (8/11) were from the skin. The current report is the first description of MRSP resistance to ceftaroline.

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 The Phenotypic and Genetic Detection of the Methicillin-Resistant Staphylococcus aureus (MRSA)

2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Eftychios V ◽  
Laura VM ◽  
Calina-Oana Z ◽  
Evangelos V ◽  
Marina P ◽  
...  
Keyword(s):  
Meca Gene ◽  
Latex Agglutination ◽  
Agglutination Test ◽  
Latex Agglutination Test ◽  
Disk Diffusion ◽  
Methicillin Resistant ◽  
Pcr Method ◽  
Resistant Strains ◽  
Mrsa Strains ◽  
Cefoxitin Disk

Methicillin resistant strains of Staphylococcus aureus (MRSA) were identified shortly upon the introduction of methicillin into the clinical practice. The S. aureus samples were taken from patients hospitalized in General Hospital of Chania “Agios Georgios”. The strains were isolated from different pathological products, in the hospital laboratory. All isolates were tested using the cefoxitin disk diffusion, the oxacillin MIC methods and the PBP2’ latex agglutination test (bioMérieux), for the production of the Penicillin-Binding Protein 2a (PBP2a or PBP2’ protein). S. aureus ATCC 29213 was used as a negative control. We followed the detection of the mecA gene throughout the PCR method, as the standard “gold” method, in order to identify MRSA strains. Conventional methods for MRSA strains detection were compared with the PCR method. The antibiotic susceptibility testing was performed throughout the Kirby-Bauer disk diffusion method using antibiotic discs from Bioanalyse ltd. The mecA gene was found by PCR in 57.5 % of S. aureus strains, which allowed defining the isolated strains as MRSA strains. According to the oxacillin MIC values of the studied strains, 25 strains (53.2%) were identified as MRSA, 21 (44.68%) as MSSA and 1*strain (2.13%) as Borderline (BL) MRSA. The mecA gene is present in 24 of the MRSA strains with oxacillin MIC ≥ 4 being more common in strains showing the oxacillin MICs ≥ 256 (12/27). Adding the BL strains to the methicillin resistant strains, the rate of the MRSA strains increases to 26 (55.32%), the appropriate values of the MRSA strains percent, as determined by the PCR method (57.45%), which shows a concordance of 96.3% (26/27), between the results obtained by the two tests. Comparing the results obtained using the PCR method; with the oxacillin MICs and the PBP2’ latex agglutination test, concordant results were obtained for 89.36% of the strains (42/47) by oxacillin MICs and for 97.87% of the strains (46/47) by PBP2’ latex agglutination test. We conclude that the specificity of these methods is 100% for the mecA PCR method, 97.87% for the PBP2a latex method and 89.36% for the oxacillin MIC. The comparison of phenotypic methods (the PBP2a latex reaction, oxacillin MICs, the Cefoxitin disk diffusion test with the genotypic methods (the presence of the mecA gene), reveals that the PBP2a latex reaction has high sensitivity (97.87%), and can be used as an alternative method to PCR for the MRSA detection, in resource constraint settings.

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