Plasmid mediated MetalloBetaLactamase MBL

1

• Plasmid mediated Metallo-Beta-Lactamase (MBL)
• Plasmid mediated
• Hydrolyses all beta-lactam (except aztreonam)
• Inhibited by EDTA
• Binds zinc (Zn 2)
• Pseudomonas aeruginosa or Enterobacteriaceae

2
MBL producing Pseudomonas aeruginosa. The
isolate is resistant to imipenem (IPM 10)
ceftazidime (CAZ 10), tazocin (TZP 55), cefepime
(FEP 10), Timentin (TIM 85), and susceptible to
aztreonam (ATM 30).
3
MBL producing Pseudomonas aeruginosa. The blank
disc contains 750 µg EDTA. The zone of inhibition
of imipenem (IPM 10) and meropenem (MEM 5) is
increased with the addition of EDTA indicating
the presence of a Metallo-Beta-Lactamase.
4
MBL producing Escherichia coli resistant to
cefotaxime (CTX 5), cefotetan (CTT 30), Augmentin
(AMC 60), and susceptible to aztreonam (ATM 30).
The blank disc contains 750 µg EDTA. Note the
borderline resistance to imipenem (IPM 10) and
the large zone around the IPM disc loaded with
750 µg EDTA.
5
MBL producing Klebsiella pneumoniae with multiple
resistance R/ imipenem (IPM 10), cefotaxime (CTX
5), cefotetan (CTT 30), and Augmentin (AMC 60).
The resistance to aztreonam (ATM 30) is due to
the presence of an ESBL (key hole). Note the
borderline resistance to IPM and the large zone
around the IPM disc loaded with 750 µg EDTA.
6
Beta-Lactamases vs Beta-Lactams
P Plasmid, C Chromosomal