TABLE 3.
Characteristics of 36 coagulase-negative staphylococcal strains misclassified as oxacillin susceptible by at least one of the susceptibility testing methods
| Isolate | Resultc of indicated reference method
|
Result of indicated oxacillin susceptibility testing method
|
||||
|---|---|---|---|---|---|---|
| mecA PCR | Oxacillin agar screen | Disk diffusion | E-test (MIC [μg/ml]) | ATB Staph | Vitek | |
| 2940 | R | R | Rb | 0.125 | S | S |
| 2910 | R | S | S | 0.25 | S | S |
| 591 | R | R | Ra | 0.25 | S | R |
| 346 | R | R | Ra | 0.38 | S | S |
| 2401 | R | R | Ra | 0.5 | S | S |
| 1089 | R | S | S | 0.75 | S | S |
| 7002 | R | R | Rb | 0.75 | S | S |
| 9992 | R | R | Ra | 1 | S | S |
| 3913 | R | S | Ra | 1 | S | S |
| 1134 | R | R | S | 1 | S | R |
| 4026 | R | R | Ra | 1 | S | R |
| 5220 | R | R | Rb | 1.5 | S | S |
| 5198 | R | R | Ra | 1.5 | S | S |
| 237 | R | R | S | 1.5 | S | S |
| 8378 | R | R | Rb | 1.5 | S | S |
| 1635 | R | R | Rb | 1.5 | S | R |
| 5603 | R | R | Ra | 1.5 | S | R |
| 6120 | R | R | Ra | 1.5 | S | R |
| 0191 | R | R | Rb | 1.5 | R | R |
| 3819 | R | R | Rb | 2 | S | S |
| 777 | R | S | Rb | 2 | S | S |
| 5438 | R | R | Ra | 2 | S | S |
| 4039 | R | R | S | 2 | S | R |
| 3246 | R | R | S | 2 | R | R |
| 5987 | R | R | Rb | 2 | R | R |
| 2971 | R | R | Rb | 3 | S | R |
| 8954 | R | R | S | 4 | R | R |
| 6587 | R | R | Ra | 8 | S | R |
| 8343 | R | R | Ra | 16 | S | R |
| 4380 | R | R | Ra | 16 | S | R |
| 4757 | R | R | R | 16 | S | R |
| 6074 | R | R | Ra | >256 | S | R |
| 7773 | R | R | Ra | >256 | S | R |
| 1096 | R | R | R | >256 | S | R |
| 3149 | R | R | Rb | >256 | S | R |
| 1092 | R | R | R | >256 | S | R |
a
Strain had a susceptible zone of inhibition (≥20 mm with the 5-μg oxacillin disk) but had colonies within the zone (heteroresistance).
b
Strain had resistant zones of inhibition (<20 mm with the 5-μg oxacillin disk) and had colonies within the zone (heteroresistance).
c
R, resistant; S, susceptible.