Table 1. Antimicrobial susceptibility and biofilm formation ability of Haemophilus influenzae clinical isolates.

Strain	Isolation site	Serotypea	Minimum inhibitory concentration (μg/mL)b						Biofilm formation (OD630) c		P valued
			Ampicillin	Ampicillin sulbactam	Cefotaxime	Clarithromycin	Azithromycin	Levofloxacin	Without OdiE	With OdiE (20 mg/mL)
2013–28	Nasal cavity	Nontypeable	0.125	0.125	≤0.063	2	0.25	≤0.063	0.253 ± 0.061	0.096± 0.032	<0.001
2013–86	Nasal cavity	Nontypeable	0.25	0.25	≤0.063	4	0.5	≤0.063	0.292 ± 0.047	0.098 ± 0.032	<0.001
2011–130	Nasal cavity	Nontypeable	8	4	1	2	0.125	≤0.063	0.193 ± 0.025	0.104 ± 0.039	<0.001

^aSerotype was determined by PCR

^bminimum inhibitory concentration was measured by the broth dilution method according to the Clinical and Laboratory Standards Institute guidelines

^cmean ± SD

^dP values were calculated by the Student's t-test.