TABLE 1.
Antibiotic susceptibility testing of LB1 and LB2 isogenic isolates by the disk diffusion methoda
| Antibiotic disk content (μg) | Breakpoint(s) from CA-SFM,b 2013 (mm) | Inhibition diam (mm) |
Susceptibility | |
|---|---|---|---|---|
| LB1 | LB2 | |||
| AMX (25) | 16–21 | 6 | 6 | R |
| AMC (30) | 16–21 | 14 | 14 | R |
| TIC (75) | 22–24 | 6 | 6 | R |
| TIM (85) | 22–24 | 20 | 20 | R |
| TZP (85) | 17–21 | 25 | 25 | S |
| FEP (30) | 21–24 | 33 | 33 | S |
| CRO (30) | 23–26 | 32 | 32 | S |
| CTX (30) | 23–26 | 36 | 36 | S |
| FOX (30) | 15–22 | 26 | 26 | S |
| IPM (10) | 17–24 | 32 | 32 | S |
| ETP (10) | 26–28 | 31 | 31 | S |
| ATM (30) | 21–27 | 35 | 35 | S |
| NAL (30) | 15–20 | 21 | 21 | S |
| CIP (5) | 22–25 | 28 | 28 | S |
| OFL (5) | 22–25 | 36 | 36 | S |
| AMK (30) | 15–17 | 20 | 20 | S |
| GEN (15) | 16–18 | 20 | 20 | S |
| TOB (10) | 16–18 | 23 | 23 | S |
| FOF (50) | 14 | 19 | 19 | S |
| SXT (25) | 13–16 | 6 | 6 | R |
| NIT (300) | 15 | 12 | 12 | R |
| CST (50) | 15 | 9 | 17 | R (LB1)/S (LB2) |
Both isolates were resistant (R) to amoxicillin (AMX), amoxicillin-clavulanate (AMC), ticarcillin (TIC), ticarcillin-clavulanate (TIM), nitrofurantoin (NIT), and trimethoprim-sulfamethoxazole (SXT) and susceptible (S) to piperacillin-tazobactam (TZP), cefepime (FEP), ceftriaxone (CRO), cefotaxime (CTX), cefoxitin (FOX), aztreonam (ATM), imipenem (IPM), ertapenem (ETP), nalidixic acid (NAL), ciprofloxacin (CIP), ofloxacin (OFX), amikacin (AMK), gentamicin (GEN), tobramycin (TOB), and fosfomycin (FOF). LB1 was resistant to colistin (CST), while LB2 was susceptible.
Comité de l'Antibiogramme—Société Française de Microbiologie (http://www.sfm-microbiologie.org/UserFiles/files/casfm/CASFM2013vjuin.pdf).