Table 6 Effect of PAβN on ciprofloxacin MICs in selected MDR K. pneumoniae isolates with high acrB expression (n = 10 biological isolates). MIC determinations were performed using broth microdilution assays conducted in biological triplicates, with each measurement confirmed in technical triplicates.

From: Integrated analysis of global regulators and efflux genes associated with antimicrobial resistance reversal in multidrug resistant Klebsiella pneumoniae

Isolate ID

acrB fold expression

MIC ciprofloxacin (µg/mL)

MIC + PAβN (µg/mL)

Fold reduction

KPN-01

6.2 × 

16

2

8 × 

KPN-03

7.5 × 

32

4

8 × 

KPN-07

5.8 × 

16

2

8 × 

KPN-10

8.3 × 

64

8

8 × 

  1. MICs were determined using the broth microdilution method according to CLSI (2025) guidelines. PAβN was used at a final concentration of 25 µg/mL. A ≥ fourfold reduction in MIC in the presence of PAβN was considered indicative of active efflux pump contribution to ciprofloxacin resistance.
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