3.1.2 Carbapenem resistance and carbapenemases
The greatest current concern for human health is from carbapenem resistance. For example, Acinetobacter, Klebsiella and Pseudomonas aeruginosa are important causes of outbreaks in tertiary and critical care. MDR- and pan-resistant strains are a problem in many critical care units. They are frequently resistant not just to carbapenems but also to all other available antimicrobials. Once they have colonised the environment in a unit, they are very hard to get rid of.
Carbapenem-resistant Enterobacterales (CPE), predominantly Klebsiella and E. coli, have been found in wild animals, livestock and pets, with evidence of direct transfer to humans (Kock et al., 2018).
The main classes of carbapenemases of clinical and veterinary importance are shown in Table 3.
| Carbapenemase class | Notes |
| KPC | Found worldwide, particularly associated with Klebsiella |
| VIM | Metallo-β-lactamases mainly found in Pseudomonas |
| IMP | Metallo-β-lactamases found in Pseudomonas, Acinetobacter and Enterobacterales |
| NDM | Metallo-β-lactamases most common at present in India and the Middle East in Enterobacterales but spread to many species. |
| OXA-48 | Most common carbapenemases in many parts of the world and evolving and spreading rapidly. Most important in K. pneumoniae and E. coli but also found in Pseudomonas where they are harder to detect. They can be missed if carbapenemase screening is not done correctly. |
Table 3 Carbapenemases important in human and animal health (abbreviations: KPC – Klebsiella pneumoniae carbapenemase; VIM – Verona integron-encoded metallo-beta-lactamase; IMP – Imipenemase metallo-beta-lactamase; NDM – New Delhi metallo-β-lactamase; OXA-48 – Oxacillin-48 carbapenemase)
3.1.1 β-lactam resistance and ESBLs
