TABLE 4.
Influence of plasmid-expressed PA5471 on norfloxacin resistance in P. aeruginosa
| Strain | Relevant property | MIC (μg/ml) of norfloxacina
|
|
|---|---|---|---|
| −Mg2+ | +Mg2+ | ||
| YM34(pUCP20T)b | MexXY+ | 0.25 | 2 |
| YM34(pYM010) | MexXY+ PA5471++c | 0.5 | 8 |
| YM44(pUCP20T) | MexXY− | 0.12 | 0.25 |
| YM44(pYM010) | MexXY− PA5471++c | 0.12 | 0.25 |
a
Norfloxacin MICs were determined in the presence and absence of 5 mM MgCl2. Mg2+ enhances MexXY-mediated antimicrobial resistance, possibly by enhancing the activity of this efflux system (28).
b
Lacks MexAB-OprM, MexCD-OprJ, and MexEF-OprN.
c
PA5471 was overexpressed from plasmid pYM010.