A NEW PLASMIDIC CEFOTAXIMASE IN A CLINICAL ISOLATE OF ESCHERICHIA-COLI

Escherichia coli GRI was isolated from an ear exudate of a newborn. The strain was highly resistant to cefotaxime (MIC 128 mg/l). Resistance to cefotaxime and the majority of β-lactam antibiotics was readily transferred to an Escherichia coli recipient strain. Both the wild type and the transconjugant strains are different in their resistance phenotype from TEM-3 β-cefotaximase producers by higher MICs to the majority of β-lactams and lower MICs to ceftazidime. The isoelectric point of the cefotaximase of E. coli GRI was 8.9 in comparison with 6.3 for TEM-3. Thus, the enzyme produced by E. coli GRI represents a new plasmidic (plasmid pMVP-3) broad spectrum β-lactamase (CTX-M) which may not be closely related to either the TEM- oder SHV-family of extended broad spectrum β-lactamases. © 1990 MMV Medizin Verlag GmbH München.