Table 1.

Characterization of β-lactamases of M. catarrhalis isolates obtained during multicenter U.S. national surveillance studies conducted from 1994 to 1995 and from 1997 to 1998

Study time and ampicillin MIC (μg/ml)Total no. (%) of β-lactamase-positive isolates in studyNo. of isolates characterized by IEFNo. (%) of BRO-1-producing isolatesaNo. (%) of BRO-2-producing isolatesa
1994 to 1995
0.062 (0.3)21 (50.0)1 (50.0)
0.126 (1.0)61 (16.7)5 (83.3)
0.2521 (3.6)2119 (90.5)2 (9.5)
0.527 (4.7)2724 (88.9)3 (11.1)
160 (10.4)6059 (98.3)1 (1.7)
2113 (19.6)4848 (100)
4162 (28.1)1010 (100)
8118 (20.5)1010 (100)
1659 (10.2)1010 (100)
327 (1.2)77 (100)
>321 (0.2)11 (100)
Total57620219012
1997 to 1998
0.065 (1.0)55 (100)
0.128 (1.6)82 (25.0)6 (75.0)
0.259 (1.8)98 (88.9)1 (11.1)
0.542 (8.6)4241 (97.6)1 (2.4)
146 (9.4)4644 (95.7)2 (4.3)
283 (17.0)5353 (100)
4156 (32.0)1010 (100)
894 (19.3)1111 (100)
1637 (7.6)1010 (100)
327 (1.4)77 (100)
>32
Total48720118615
  • a Isolates characterized by IEF which revealed the BRO-1 or BRO-2 profile.