Characterization of an Ampicillin-Resistant Haemophilus influenzae Type B

Abstract

A 28-year-old female in Denver was found in early 1974 to have frontal sinusitis, osteomyelitis, and bacteremia due to Haemophilus influenzae, type B. The minimal inhibitory concentration of ampicillin for this organism was 100 ,ug/ml and the minimal bactericidal concentration was >100 ,zg/ml. It was inhibited by chloramphenicol at 0.4 gg/ml. Further studies demonstrated that ampicillin and methicillin were synergistic against this organism. It was shown to produce a diffusible beta-lactamase. Transferase of resistance from this organism to a susceptible Haemophilus parainfluenzae and a reciprocal transfer were accomplished. A test for transformation was negative as was a test for reversal of resistance by ethylenediaminetetraacetic acid.

Plasmid transfer in Haemophilus influenzae

“…In the last few years several laboratories and hospitals have reported the isolation of Haemophilus cultures that were highly resistant to certain antibiotics such as ampicillin (Ap), chloramphenicol (Cm), kanamycin (Km), and tetracycline (Tc) (15,18,22,25,37,38). In some instances these resistances were traced directly to the presence of plasmids (7,8,10,12,19,23,35,38). Not surprisingly, perhaps, some of these plasmids transferred from donor to recipient cell by a process requiring cell-to-cell contact (7, 13, 19, 36, 39; and J. Lewis, M. S. thesis, Florida State University, Tallahassee, Fla., 1977), whereas others could be transferred in the laboratory by transformation (8,29).…”

Beta-Lactamase Production and Resistance to Beta-Lactam Antibiotics in Nocardia

“…The resultant enzyme preparation showed similar activity (Fig. 4), with the same substrate profile as the whole-cell supernatants from the seven iso- The MICs of ampicillin for these strains were: a, 1.6 p1g/ml; b, 1.6 pg/ml; c, 6.3 pg/ml; d, 12.5 pg/ml; e, 50 pg/ml; and f, 100 pg/ml. Strain a was negative for beta-lactamase when the chromogenic cephalosporin compound 87/312 and intact cells were used, whereas the other five strains were positive.…”

“…Beta-lactamase activity was assayed by using a modification of the technique described by Eickhoff et al with Haemophilus influenzae (6). A 0.1-mi quantity of the crude enzyme was added to 0.5 ml of the test penicillin or cephalosporin which had been suspended in TSB at a concentration of 100 yg/ml.…”

Haemophilus influenzae: antibiotic susceptibility.

“…Media for growth of H. influenzaea 10% Fildes ................................. 111, 123 MHB + 5% Fildes ................................ 30,110. MHB + 5% Fildes + 1% supplement C .. 98.…”