Last data update: May 13, 2024. (Total: 46773 publications since 2009)
Records 1-3 (of 3 Records) |
Query Trace: Swenson JM[original query] |
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A multicenter study to determine disk diffusion and broth microdilution criteria for prediction of high- and low-level mupirocin resistance in Staphylococcus aureus
Swenson JM , Wong B , Simor AE , Thomson RB , Ferraro MJ , Hardy DJ , Hindler J , Jorgensen J , Reller LB , Traczewski M , McDougal LK , Patel JB . J Clin Microbiol 2010 48 (7) 2469-75 Mupirocin susceptibility testing of Staphylococcus aureus has become more important as mupirocin is used more widely to suppress or eliminate S. aureus colonization and prevent subsequent healthcare- and community-associated infections. This multi-center study evaluated two susceptibility testing screening methods to detect high-level mupirocin resistance (HLR), broth microdilution (BMD) MIC of ≥ 512 mug/ml and a 6 mm zone diameter for a 200-mug disk diffusion (DD) test. Initial testing indicated that with Clinical and Laboratory Standards Institute methods for BMD and DD, optimal conditions for detection of mupirocin HLR were 24 hours of incubation and reading DD zone diameters with transmitted light. Using the presence or absence of mupA as the gold standard for HLR, the sensitivity and specificity of a single-well 256 mug/ml BMD test were 97 and 99%, and for the 200-mug disk test were 98 and 99%, respectively. Testing with two disks, 200 mug and 5 mug, was evaluated for distinguishing HLR isolates (MIC ≥ 512 mug/ml), low-level resistant (LLR) isolates (MIC 8-256 mug/ml), and susceptible isolates (MIC ≤ 4 mug/ml). Using no zone with both disks as an indication of HLR, and no zone with the 5-mug disk plus any zone with the 200-mug disk as LLR, only 3 of the 340 isolates were misclassified, with 3 susceptible isolates being classified as LLR. Use of standardized MIC or disk tests could enable the detection of emerging high- and low-level mupirocin resistance in S. aureus. |
Accuracy of commercial and reference susceptibility testing methods for detecting vancomycin-intermediate Staphylococcus aureus
Swenson JM , Anderson KF , Lonsway DR , Thompson A , McAllister SK , Limbago BM , Carey RB , Tenover FC , Patel JB . J Clin Microbiol 2009 47 (7) 2013-7 We compared the results obtained with six commercial MIC test systems (Etest, MicroScan, Phoenix, Sensititre, Vitek Legacy, and Vitek 2 systems) and three reference methods (agar dilution, disk diffusion, and vancomycin [VA] agar screen [VScr]) with the results obtained by the Clinical and Laboratory Standards Institute broth microdilution (BMD) reference method for the detection of VA-intermediate Staphylococcus aureus (VISA). A total of 129 S. aureus isolates (VA MICs by previous BMD tests, <or=1 microg/ml [n = 60 strains], 2 microg/ml [n = 24], 4 microg/ml [n = 36], or 8 microg/ml [n = 9]) were selected from the Centers for Disease Control and Prevention strain collection. The results of BMD with Difco Mueller-Hinton broth were used as the standard for data analysis. Essential agreement (percent +/-1 dilution) ranged from 98 to 100% for all methods except the method with the Vitek Legacy system, for which it was 90.6%. Of the six commercial MIC systems tested, the Sensititre, Vitek Legacy, and Vitek 2 systems tended to categorize VISA strains as susceptible (i.e., they undercalled resistance); the MicroScan and Phoenix systems and Etest tended to categorize susceptible strains as VISA; and the Vitek Legacy system tended to categorize VISA strains as resistant (i.e., it overcalled resistance). Disk diffusion categorized all VISA strains as susceptible. No susceptible strains (MICs <or= 2 microg/ml) grew on the VScr, but all strains for which the VA MICs were 8 microg/ml grew on the VScr. Only 12 (33.3%) strains for which the VA MICs were 4 microg/ml grew on VScr. The differentiation of isolates for which the VA MICs were 2 or 4 microg/ml was difficult for most systems and methods, including the reference methods. |
Correlation of cefoxitin MICs with the presence of mecA in Staphylococcus spp
Swenson JM , Brasso WB , Ferraro MJ , Hardy DJ , Knapp CC , Lonsway D , McAllister S , Reller LB , Sader HS , Shortridge D , Skov R , Weinstein MP , Zimmer BL , Patel JB . J Clin Microbiol 2009 47 (6) 1902-5 This report describes the results of an 11-laboratory study to determine if a cefoxitin broth microdilution MIC test could predict the presence of mecA in staphylococci. Using breakpoints of < or = 4 microg/ml for mecA-negative and > or = 6 or 8 microg/ml for mecA-positive isolates, sensitivity and specificity based on mecA or presumed mecA for Staphylococcus aureus at 18 h of incubation were 99.7 to 100% in three cation-adjusted Mueller-Hinton broths tested. For coagulase-negative strains at 24 h of incubation, breakpoints of < or = 2 microg/ml for mecA-negative and > or = 4 microg/ml for mecA-positive isolates gave sensitivity and specificity of 94 to 99% and 69 to 80%, respectively. |
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