Emergence of clinical Escherichia coli isolates with decreased susceptibility to ceftazidime and synergic effect with co-amoxiclav due to SHV-1 hyperproduction.
Between 1994 and 1996 we detected 28 out of 7054 (0.4%) clinical isolates of Escherichia coli with abnormal or reduced inhibition diameters to co-amoxiclav and ceftazidime in a disc diffusion test. The increased MIC of ceftazidime (1-32 mg/L) and the effect of synergy between this antibiotic and co-amoxiclav according to the disc diffusion test suggest the presence of an extended-spectrum beta-lactamase. However, enzymatic characterization and the nucleotide sequence confirm the hyperproduction of the SHV-1 enzyme.
Miró
E
E
Servei de Microbiologia, Hospital de Sant Pau, Barcelona, Spain.
del Cuerpo
M
M
Navarro
F
F
Sabaté
M
M
Mirelis
B
B
Prats
G
G
D019980:Amoxicillin-Potassium Clavulanate Combination / Q000494:pharmacology*; D002442:Ceftazidime / Q000494:pharmacology*; D004269:DNA, Bacterial / Q000032:analysis; D004359:Drug Therapy, Combination / Q000494:pharmacology*; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000187:drug effects* / Q000201:enzymology / Q000302:isolation & purification; D006801:Humans; D007525:Isoelectric Focusing; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D012703:Serotyping; D013030:Spain; D001618:beta-Lactamases / Q000096:biosynthesis*
D004269:DNA, Bacterial; D019980:Amoxicillin-Potassium Clavulanate Combination; D002442:Ceftazidime; C054882:beta-lactamase PIT-2; D001618:beta-Lactamases