Ampicillin treatment failure of apparently beta-lactamase-negative Haemophilus influenzae type b meningitis due to novel beta-lactamase

Lancet. 1981 Nov 7;2(8254):1008-10. doi: 10.1016/s0140-6736(81)91214-9.


Documented ampicillin treatment failures of systemic Haemophilus influenzae type b infections have been associated with synthesis of a TEM-1 beta-lactamase. A patient with H. influenzae type b meningitis in whom ampicillin treatment failed is described; the isolate was beta-lactamase-negative according to the cell suspension chromogenic cephalosporin assay. The false-negative result occurred in a strain which elaborated a novel, plasmid-mediated beta-lactamase with characteristics which distinguish it from TEM-1 beta-lactamase. Clinically important ampicillin resistance in H. influenzae type b occurs by mechanisms other than by synthesis of TEM-1 beta-lactamase. Diagnostic microbiology laboratories should perform antibiotic susceptibility tests in addition to tests for beta-lactamase production.

Publication types

  • Case Reports
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Ampicillin / pharmacology
  • Ampicillin / therapeutic use*
  • Female
  • Haemophilus influenzae / classification
  • Haemophilus influenzae / drug effects*
  • Haemophilus influenzae / enzymology
  • Haemophilus influenzae / genetics
  • Humans
  • Infant
  • Meningitis, Haemophilus / drug therapy*
  • Penicillin Resistance
  • Plasmids
  • beta-Lactamases / biosynthesis
  • beta-Lactamases / genetics


  • Ampicillin
  • beta-Lactamases