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Klebsiella oxytoca and K1 enzyme (indole positive) Chromosomal R/ ampicillin Mutational hyperproduction R/ cephalosporins Less susceptible to clavulanic acid than ESBL No key hole Key hole not obvious.
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Klebsiella oxytoca • and K1 enzyme • (indole positive) • Chromosomal • R/ ampicillin • Mutational hyperproduction • R/ cephalosporins • Less susceptible to clavulanic acid than ESBL • No key hole • Key hole not obvious
A Klebsiella oxytoca with basal K1 b-lactamase resistant to ampicillin and susceptible to Augmentin, cephalexin and cefotaxime.
A hyperproducer Klebsiella oxytoca with a high level of mutational K1 b-lactamase shows resistance to Augmentin, cephalexin and cefotaxime.
Anotherhyperproducer Klebsiella oxytoca with a high level of mutational K1 b-lactamase. Note the tiny "keyhole" between cefotaxime (CTX 5) and Augmentin (AMC 60) and the small inhibitory zone around cephalexin (CL100). The tiny "keyhole“ is a “bonus” as most strains with high K1 activity simply show resistance to Augmentin, cephalexin and cefotaxime.
Ahyperproducer Klebsiella oxytoca with a low level of mutational K1 b-lactamase. Note the slight synergy between Augmentin (AMC 60) and the cephalosporin discs cephalexin (CL100) and cefotaxime (CTX 5).
A Klebsiella oxytoca with an ESBL. It’s likely that the isolate only has basal K1 b-lactamase (large zone around AMC 60).
Reporting • Klebsiella oxytoca hyperproducer of K1 • Not ESBL (plasmid mediated) • As per Table 4 • R/ ampicillin, cephalexin, cefotaxime…..