Table 1.
Role of Stk1 in β-lactam resistance of methicillin-resistant S. aureus (MW2 and LAC).
| MIC (µg/mL) | PEN | AMP | NAF | CXM | CAZ | FEP | IPM |
|---|---|---|---|---|---|---|---|
| Newman (MSSA) | 0.094 | 0.25 | 0.25 | 1.5 | 16 | 4 | 0.032 |
| MW2 | 48 | 24 | 32 | >256 | >256 | >256 | 1 |
| MW2∆stk1 | 12 | 12 | 2 | 6 | 32 | 8 | 0.125 |
| LAC | 48 | 32 | 16 | >256 | >256 | >256 | 0.75 |
| LAC∆stk1 | 24 | 24 | 4 | 6 | 12 | 4 | 0.06 |
PEN = Penicillin; AMP = Ampicillin; NAF = Nafcillin; CXM = Cefuroxime; CAZ = Caftazidime; FEP = Cefepime; IMI = Imipenem. Minimal inhibitory concentration (MIC) was determined using either Etest strips (AB Biodisk) or growth in liquid broth. For MIC determination in liquid growth, overnight cultures of MRSA strains were inoculated 1:20 in Typtic Soy Broth (TSB) containing different antibiotic concentrations.