scholarly journals Evaluation of Mannitol Salt Agar for Detection of Oxacillin Resistance in Staphylococcus aureus by Disk Diffusion and Agar Screening

1998 ◽  
Vol 36 (8) ◽  
pp. 2254-2257 ◽  
Author(s):  
Günter Kampf ◽  
Christoph Lecke ◽  
Ann-Katrin Cimbal ◽  
Klaus Weist ◽  
Henning Rüden
Keyword(s):  
Staphylococcus Aureus ◽  
Disk Diffusion ◽  
Diffusion Test ◽  
Mannitol Salt Agar ◽  
Disk Diffusion Test ◽  
Zone Diameter ◽  
Oxacillin Resistance

Mannitol salt agar was evaluated for detection of oxacillin resistance in 136 Staphylococcus aureus isolates. AllmecA-positive isolates (n = 54) were correctly categorized as oxacillin resistant by the disk diffusion test (1-μg disk; zone diameter, <16 mm); the specificity was 97.6%. Agar screening (2 μg of oxacillin per ml) revealed a sensitivity of 98.1% and a specificity of 95.1%.

scholarly journals Cefazolin inoculum effect among methicillinsusceptible Staphylococcus aureus isolated from patients with skin infections

2021 ◽  
Vol 23 (2) ◽  
pp. 205-211
Author(s):  
Anastasia N. Vaganova ◽  
S.V. Borisenko ◽  
E.V. Nesterova ◽  
N.N. Trofimova ◽  
I.V. Litvinenko ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Real Time ◽  
Real Time Pcr ◽  
Disk Diffusion ◽  
Skin Infections ◽  
Beta Lactamase ◽  
Broth Microdilution ◽  
Diffusion Test ◽  
Disk Diffusion Test ◽  
Inoculum Effect

Objective. To evaluate frequency and intensity of cefazolin inoculum effect among methicillin-susceptible staphylococci isolated from patients with skin infections. Materials and Methods. A total of 80 methicillin susceptible isolates of Staphylococcus aureus were identified by cefoxitin disk-diffusion test and negative results of real-time PCR for mecA gene. Inoculum effect was measured by broth microdilution test with two inocula with concentrations of 5 × 105 CFU/mL and 5 × 107 CFU/mL. The disk-diffusion test with cefoxitin was also performed. Penicillin susceptibility was determined by disk-diffusion method. Beta-lactamase blaZ gene was identified by real-time PCR. Results. The frequency of cefazolin inoculum effect in tested isolates was 30% which is consistent with data from different countries. The MIC values for concentrated inoculum reached CLSI breakpoint for cefazolin resistance in 2.5% of isolates. The isolates with inoculum effect and those without it had the similar MIC values for cefazolin in broth microdilution test for standard inocula and similar diameters of inhibition zone in disk-diffusion test with cefazolin. Penicillin resistance was more frequent in inoculum effect-positive isolates. Beta-lactamase activity is considered as a main cause of cefazolin inoculum effect in staphylococci. The beta-lactamase blaZ gene was identified in the majority of isolates with cefazolin inoculum effect, but it was also prevalent among inoculum effect-negative isolates. Conclusions. Up to 30% of MSSA isolates from skin lesions in dermatological patients from SaintPetersburg are positive for cefazolin inoculum effect. Those isolates are usually characterized by penicillin resistance. Most of the cefazolin inoculum effect-positive isolates also carry beta-lactamase blaZ gene.

scholarly journals Evaluation of MRSA-Screen, a Simple Anti-PBP 2a Slide Latex Agglutination Kit, for Rapid Detection of Methicillin Resistance in Staphylococcus aureus

1999 ◽  
Vol 37 (5) ◽  
pp. 1591-1594 ◽  
Author(s):  
Matthias Cavassini ◽  
Aline Wenger ◽  
Katia Jaton ◽  
Dominique S. Blanc ◽  
Jacques Bille
Keyword(s):  
Staphylococcus Aureus ◽  
Monoclonal Antibody ◽  
Screening Test ◽  
Rapid Detection ◽  
Methicillin Resistance ◽  
Screen Test ◽  
Latex Agglutination ◽  
Disk Diffusion ◽  
Diffusion Test ◽  
Disk Diffusion Test

The MRSA-Screen test (Denka Seiken Co., Ltd., Tokyo, Japan), consisting of a slide latex agglutination kit that detects PBP 2a with a monoclonal antibody, was blindly compared to the oxacillin disk diffusion test, the oxacillin-salt agar screen, and PCR of themecA gene for the detection of methicillin resistance inStaphylococcus aureus. A total of 120 methicillin-susceptible S. aureus (MSSA) and 80 methicillin-resistant S. aureus (MRSA) isolates, defined by the absence or presence of the mecA gene, respectively, were tested. The MRSA-Screen test, the oxacillin disk diffusion test, and the oxacillin-salt agar screening test showed sensitivities of 100, 61.3, and 82.5% and specificities of 99.2, 96.7, and 98.3%, respectively. We conclude that the MRSA-Screen is a very accurate, reliable, and fast test (15 min) for differentiation of MRSA from MSSA colonies on agar plates.

scholarly journals Performance of vancomycin and teicoplanin disk diffusion test in isogenic vancomycin non-susceptible Staphylococcus aureus

2015 ◽  
Vol 9 (02) ◽  
pp. 157-164 ◽  
Author(s):  
Sujintana Wongthong ◽  
Karnjana Dutchanutouch ◽  
Viladda Namsaengkang ◽  
Aroonwadee Chanawong ◽  
Chotechana Wilailuckana ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Predictive Value ◽  
Population Analysis ◽  
Area Under The Curve ◽  
Serial Passage ◽  
Disk Diffusion ◽  
Diffusion Test ◽  
Disk Diffusion Test ◽  
Methicillin Resistant

Introduction: Detection of heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) is currently problematic. Although the population analysis profile with area under the curve (PAP-AUC) is the gold standard for detecting hVISA strains, this method is time consuming. This study aimed to induce vancomycin non-susceptible Staphylococcus aureus isolates in methicillin-resistant S. aureus (MRSA) and to determine the performance of the vancomycin and teicoplanin disk diffusion test for screening of induced and natural vancomycin non-susceptible isolates. Methodology: Vancomycin resistance was induced in vitro in methicillin-resistant S. aureus by serial passage in media with increasing vancomycin concentrations. All test isolates were confirmed for their susceptibility to vancomycin by using a PAP-AUC method. The performance of the vancomycin and teicoplanin disk diffusion test for detecting both induced and natural hVISA/VISA isolates was analyzed using the MedCal program version 10.2.0. Results: The induction test revealed that 42 of 78 MRSA isolates (53.8%) became hVISA and/or VISA. Using 10, 15, 20, 30 µg vancomycin disks and a 30 µg teicoplanin disk, the highest performance (88.9%) for hVISA/VISA detection (71.1%, sensitivity, 100% specificity, 100% positive predictive value, and 75% negative predictive value) was obtained when a 20 µg vancomycin disk was used at 1.0 McFarland inoculum for a 24-hour incubation. Conclusions: The results indicated that using a 20 µg vancomycin disk and bacterial inoculum of 1.0 McFarland is simple to perform and provides a primary result for hVISA/VISA screening within 24 hours.

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