Table 2.

Amino acid substitutions in PBP-3 of 36 invasive β-lactamase-negative β-lactam-resistant H. influenzae isolates^a

BLNAR genotype	n	Amino acid substitution															Ampicillin MICb (range; mg/liter)
		Asp 350	Ala 368	Asp 373	Met 377	Ala 395	Ala 437	Ile 449	Ile 475	Gly 490	Ala 502	Arg 517	Asn 526	Ala 530	Val 547	Asn 569
I	1											His					1
IIb	8	Asn			Ile						Val		Lys		Ile	Ser	0.5–4
IIb	2	Asn			Ile					Glu	Val		Lys		Ile	Ser	2
IIb	1			Asn		Gly					Val		Lys		Ile	Ser	2
IIb	1				Ile						Val		Lys		Ile		8
IId	2							Val					Lys		Ile	Ser	2
II	1	Asn								Glu			Lys	Ser			0.5
—c	3	Asn													Ile	Ser	0.25–0.5
—	2	Asn					Ser								Ile	Ser	0.5
—	2			Asn													0.5
—	1								Leu								1
—	2		Thr														0.25–0.5
—	3														Ile		0.25
—	7	(No substitutiond)															0.25–256

^aAll gBLNAR variants are highlighted in boldface.

^bMICs were determined by Etest.

^c—, the isolate was not gBLNAR.

^dTwo strains produced β-lactamases (BLPACR) and therefore there was a broad MIC range.