Abstract
Four strains of Enterobacter spp. with different chromosomal β-lactamase expression (inducible, constitutive or negligible) were grown in broth containing either cefoxitin or cefotaxime, then plated on to agar containing 20 mg cefotaxime per litre to quantitate the cefotaxime-resistant mutants present in the population. Spontaneous resistant mutants were initially isolated from each strain at frequencies of 10-4 to 10-5. These high frequencies of spontaneous mutation suggested that more than one type of mutational event could yield cefotaxime resistance. Induction of a high level of β-lactamase in broth cultures was not in itself sufficient to confer a high level of cefotaxime resistance on the population, and increased resistance following selection of resistant mutants did not necessarily correlate with any significant increase in β-lactamase activity.
| Original language | English |
|---|---|
| Pages (from-to) | 489-496 |
| Number of pages | 8 |
| Journal | Journal of Antimicrobial Chemotherapy |
| Volume | 20 |
| Issue number | 4 |
| DOIs | |
| Publication status | Published - Oct 1987 |
| Externally published | Yes |
Bibliographical note
Funding Information:J. M. H. gratefully acknowledges the support of a Cooperative Award in Science and Engineering from the Science and Engineering Research Council.
