Antimicrobial resistance is a growing concern with the emergence of methicillin resistant staphylococcus aureus (MRSA), vancomycin resistant enterococcus (VRE), and now carbapenem-resistant enterobacteriaceae (CRE).  The CDC issued a statement that CRE are an “important threat to public health” and are sometimes referenced as “nightmare bacteria” in the media.  Treatment options are particularly limited for CRE, making infection with these organisms an emerging health care concern.

Carbapenemase production most commonly occurs with Escherichia coli and Klebsiella pneumoniae, but can occur with any member of the Enterobacteriaceae family.  Infections are uncommon in healthy individuals, but more commonly occur in those exposed to frequent antibiotic administration, those undergoing prolonged or repeated hospitalizations, or individuals living in skilled nursing facilities.  Transmission occurs person-to-person, typically from ineffective hand washing. Transmission has also been noted to occur from contaminated endoscopy scopes, as the stool is a main site of enterobacteriaceae.  Careful handwashing after patient contact, especially when cleaning stool or caring for wounds or wound dressings helps to prevent the spread of CRE. Hospitals should follow strict protocols for cleaning endoscopy equipment to prevent organism spread. Patients with CRE should be placed on contact isolation according to the CDC protocol.

CRE confers antimicrobial resistance to beta-lactams, carbapenems, trimethoprim/sulfamethoxazole, fluoroquinolones, tetracyclines, and aminoglycosides. This leaves only the potential for treatment with tigecycline and colistin, though treatment decisions must be individualized based on microbiology findings, infection site, and patient specific data. Tigecycline often reaches insufficient concentrations for treating serious infections such as bacteremia, and colistin has serious side effects such as neuropathy.

Though these infections remain uncommon, they remain an important health concern as the CDC warns that infections with CRE may confer mortality rates up to 50%. 

Read more about Carbapenem-Resistant Enterobacteriaceae (CRE) here:

Harrison's Principles of Internal Medicine, 19e, Chapter 186: Diseases Caused by Gram-Negative Enteric Bacilli

https://www.cdc.gov/hai/organisms/cre/index.html

https://www.cdc.gov/hai/organisms/cre/cre-clinicianfaq.html