Table 1.
MICs for polymyxin B and closantel against the A. baumannii strains examined in this study.
| Strain | MDRa | Polymyxin susceptibilityb | MICs (mg/L)
|
||
|---|---|---|---|---|---|
| Polymyxin B | Closantel | Closantel in the presence of 2 mg/L polymyxin Bc | |||
| ATCC 19606 | No | S | 0.5 | >128 | NPd |
| FADDI-AB009e | No | S (HR) | 0.5 | >128 | NP |
| 2382 | Yes | S | 0.5 | >128 | NP |
| 2949e | Yes | S (HR) | 1 | >128 | NP |
| FADDI-AB065 | No | R | 128 | 0.5 | 0.5 |
| FADDI-AB085 | No | R | 32 | 0.5 | 0.5 |
| 2384 | Yes | R | 8 | >128 | 1 |
| 2949A | Yes | R | 64 | >128 | 2 |
a
Multidrug resistance (MDR) was defined as non-susceptible to ≥1 treating agent in ≥3 antimicrobial categories.12
b
CLSI breakpoints (S, susceptible; R, resistant): Polymyxin B, S ≤2 mg/L, R ≥4 mg/L; breakpoints are not available for closantel.
c
Closantel MICs in the presence of 2 mg/L of polymyxin B.
d
Not performed (NP) for polymyxin-susceptible isolates.
e
Polymyxin B heteroresistant (HR). Heteroresistance to polymyxin B was defined as the existence, in an isolate for which the polymyxin B MIC was ≤2 mg/L, of subpopulations able to grow in the presence of >2 mg/L polymyxin B.9