A step from IAMM Delhi! You can share the common problems related to antimicrobial susceptibility testing (any bacteria / fungal spp.) or want to share antimicrobial susceptibility data through this blog.
Hurray! Long felt need! nice to find one like this. 1.how is response of cefoxitin disc in comparison to oxacillin disc? 2. how is your chloramphenicol sensitivity in MRSA? Any comments? Sangita
Unlike western literature, Cefoxitin results do not correlate well with our isolates. Probably reason lies in - ..."Because of the rare occurrence of resistance mechanisms other than mecA, if MIC tests are performed in addition to disk diffusion, isolates for which oxacillin MICs are ≥4 μg/mL and are mecA negative or PBP 2a negative should be reported as oxacillin resistant. These isolates may test as susceptible to cefoxitin by disk diffusion." Therefore, we continue to rely on Oxacillin disc rather than Cefoxitin. 2. Chloramphenicol is generally NOT a Drug of Choice for the treatment of MRSA infections. Sensitivity to chloramphenicol in our setup for S. aureus (Both MRSA and MSSA) is NO more than 50-60%.
We need to rely more on tests like PBP2" latex agglutination tests (as recommended by CLSI, with control of course)to label an isolate as MRSA.In fact we must divide the isolates as MRSA's positive or negative for PBP2" gene, thereby quoting the mechanism other than the presence of mecA.
3 comments:
Hurray! Long felt need! nice to find one like this.
1.how is response of cefoxitin disc in comparison to oxacillin disc?
2. how is your chloramphenicol sensitivity in MRSA? Any comments?
Sangita
Unlike western literature, Cefoxitin results do not correlate well with our isolates. Probably reason lies in - ..."Because of the rare occurrence of resistance mechanisms other than mecA, if MIC tests are performed in addition to disk diffusion, isolates for which oxacillin MICs are ≥4 μg/mL and are mecA negative or PBP 2a negative should be reported as oxacillin resistant. These isolates may test as susceptible to cefoxitin by disk diffusion." Therefore, we continue to rely on Oxacillin disc rather than Cefoxitin.
2. Chloramphenicol is generally NOT a Drug of Choice for the treatment of MRSA infections. Sensitivity to chloramphenicol in our setup for S. aureus (Both MRSA and MSSA) is NO more than 50-60%.
We need to rely more on tests like PBP2" latex agglutination tests (as recommended by CLSI, with control of course)to label an isolate as MRSA.In fact we must divide the isolates as MRSA's positive or negative for PBP2" gene, thereby quoting the mechanism other than the presence of mecA.
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