Table 2.

Proportion of polymyxin-resistant subpopulations of examined isolates before and after 24 hours treatment with polymyxin B (PB) alone, closantel (CLO) alone, and polymyxin B plus closantel.

A. baumannii strains	Proportion of polymyxin B-resistant subpopulations able to grow on agar supplemented with 4 mg/L polymyxin B
	Baseline	After 24 hours treatment
		Control	PB 2.0 mg/L	CLO 16 mg/L	PB 2.0 mg/L + CLO 2.0 mg/L	PB 2.0 mg/L + CLO 4.0 mg/L	PB 2.0 mg/L + CLO 16 mg/L
Polymyxin-susceptible
ATCC 19606	NDa	3.33 × 10−8	ND	ND	ND	NGb	NG
FADDI-AB009c	5.00 × 10−7	5.00 × 10−6	NG	1.00 × 10−6	NG	NG	NG
2382	ND	ND	NG	ND	NG	NG	NG
2949c	3.33 × 10−5	1.67 × 10−5	9.17 × 10−1	4.17 × 10−6	5.91 × 10−3	NG	NG
Polymyxin-resistant
FADDI-AB065	8.96 × 10−1	7.46 × 10−1	1.86	1.00	NG	NG	NG
FADDI-AB085	1.52	1.29	2.14	1.12 × 10−2	1.77	NG	NG
2384	4.75 × 10−1	2.90 × 10−1	1.97 × 10−1	5.95 × 10−1	4.82 × 10−1	4.89 × 10−1	2.55 ×s 10−2
2949A	1.01	1.74	1.62	1.38	1.13	1.42	1.31

^aNo polymyxin-resistant subpopulations detected (ND)

^bNo growth detected after 24 hours (NG)

^cPolymyxin B heteroresistant isolates