TABLE 2.

Killing activities of temocillin, piperacillin, ceftazidime, imipenem, and meropenem alone or in combination with ciprofloxacin and/or tobramycin or rifampin after 24 h of incubation^a

Antibiotic(s)	Mean ± SD change in log10 CFU/ml after 24 h of incubation
	Alone	Temocillin	Piperacillin	Ceftazidime	Imipenem	Meropenem
Alone		−0.96 ± 1.89	−0.23 ± 2.12	−1.14 ± 2.10	2.8 ± 1.49	0.41 ± 2.58
With ciprofloxacin
Asb	1.44 ± 1.94	−2.05 ± 1.6c	−2.7 ± 0.77d	−2.42 ± 1.24c	−0.24 ± 3.14d	−3.31 ± 0.36de
Ciprf	3.8 ± 0.8	−1.0 ± 2.4	−1.9 ± 1.55	−1.9 ± 2.55	2.4 ± 1.94	−2.7 ± 0.0
With tobramycin	NDg	−1.32 ± 2.26c	−1.37 ± 1.70c	−1.22 ± 2.07c	2.14 ± 2.18c	−0.62 ± 2.55c
With rifampin	ND	0.56 ± 1.89c	−1.20 ± 1.65c	−0.65 ± 1.84c	0.84 ± 3.44c	0.03 ± 3.19c
With ciprofloxacin and tobramycin
As	1.4 ± 2.0	−2.6 ± 1.72ch	−2.92 ± 0.33dh	−3.1 ± 0.74dh	−0.85 ± 2.49dh	−3.15 ± 0.59dh
Cipr	3.88 ± 0.83	−0.4 ± 3.2	−2.7 ± 0.42	−2.83 ± 1.25	1.3 ± 2.2	−2.61 ± 0.55
With ciprofloxacin and rifampin
As	1.24 ± 2.1	−2.4 ± 1.94ci	−2.98 ± 0.14di	−2.61 ± 1.0di	−1.47 ± 2.28di	−3.04 ± 0.89di
Cipr	3.88 ± 0.83	−0.05 ± 3.74	−3.05 ± 0.1	−1.97 ± 1.8	0.3 ± 3.0	−2.85 ± 0.21
With rifampin and tobramycin	ND	−1 ± 1.98c	−2.1 ± 1.13d	−2.3 ± 1.73c	0.01 ± 3.2d	−2.4 ± 2.28d
Growth control		4.5 ± 0.4	4.34 ± 0.4	4.55 ± 0.4	4.44 ± 0.35	4.3 ± 0.6

^aUnless indicated otherwise, all antibiotics were tested at 1× the MIC. Imipenem, rifampin, and ciprofloxacin (for ciprofloxacin-resistant strains) and tobramycin were tested at the usual concentrations achieved in sputum (2 and 1 μg/ml, respectively). 

^bAs, all strains. 

^cP > 0.05 compared with the β-lactam tested alone. 

^dP < 0.05 compared with the β-lactam tested alone. 

^eP < 0.05 (meropenem-ciprofloxacin compared with other β-lactam agent–ciprofloxacin). 

^fCiprofloxacin-resistant strains (n = 3). 

^gND, not determined. 

^hP > 0.05 (β-lactam–ciprofloxacin–tobramycin compared with β-lactam–ciprofloxacin). 

ⁱP > 0.05 (β-lactam–ciprofloxacin–rifampin compared with β-lactam–ciprofloxacin).