Ampicillin resistance in Hemophilus parainfluenzae

C. N. Walker, P. W. Smith

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Ampicillin resistance among strains of Hemophilus is usually due to production of beta-lactamase. This paper reports the isolation of a strain of H. parainfluenzae resistant to ampicillin with no detectable beta-lactamase or amidase activity. The organism, isolated from the blood of a patient who had aortic valve endocarditis, gave a zone diameter consistent with ampicillin sensitivity when tested by disc diffusion in Mueller-Hinton agar supplemented with 1% IsoVitaleX and 1% hemoglobin. Broth dilution testing in Levinthal medium, however, revealed the following minimal inhibitory concentrations: ampicillin, 32 μg/ml; penicillin, 256 μg/ml; methicillin, 128 μg/ml; carbenicillin, 128 μg/ml; and cephalothin and chloramphenicol, 1.0 μg/ml. The results of acidimetric, iodometric, and chromogenic cephalosporin methods for detection of beta-lactamase were negative. Beta-lactamase activity could not be demonstrated in cell sonicates or induced by growth of the cells in antibiotic-containing medium. In addition, no extracellular degradation of either ampicillin or penicillin could be demonstrated.

Original languageEnglish (US)
Pages (from-to)229-232
Number of pages4
JournalAmerican journal of clinical pathology
Volume74
Issue number2
DOIs
StatePublished - Jan 1 1980

Fingerprint

Haemophilus parainfluenzae
Ampicillin Resistance
Ampicillin
beta-Lactamases
amidase
Penicillins
Haemophilus
Carbenicillin
Cephalothin
Methicillin
Chloramphenicol
Cephalosporins
Endocarditis
Aortic Valve
Agar
Hemoglobins
Anti-Bacterial Agents
Growth

ASJC Scopus subject areas

  • Pathology and Forensic Medicine

Cite this

Ampicillin resistance in Hemophilus parainfluenzae. / Walker, C. N.; Smith, P. W.

In: American journal of clinical pathology, Vol. 74, No. 2, 01.01.1980, p. 229-232.

Research output: Contribution to journalArticle

Walker, C. N. ; Smith, P. W. / Ampicillin resistance in Hemophilus parainfluenzae. In: American journal of clinical pathology. 1980 ; Vol. 74, No. 2. pp. 229-232.
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