Tracking CRE

Bacteria are constantly finding new ways to avoid the effects of antibiotics. For example, some Enterobacteriaceae can produce enzymes called carbapenemases that break down antibiotics including carbapenems, making the drugs ineffective. Carbapenem antibiotics are typically reserved to treat multidrug-resistant bacterial infections, so when bacteria develop resistance to them, treatment options can be extremely limited.

As of 2018, CDC is tracking carbapenemase enzymes in CRE using data generated by the Antibiotic Resistance Laboratory Network (AR Lab Network) and CDC laboratories. The AR Lab Network is not a surveillance network and therefore does not represent testing of every isolate in each state. The AR Lab Network routinely tests for the following carbapenemases:

• K. pneumoniae carbapenemase (KPC): This was first identified in the United States around 2001 and is the most common carbapenemase in the United States.
• New Delhi Metallo-beta-lactamase (NDM): A less common carbapenemase in the United States but concerning because it can be resistant to even more antibiotics than KPC.
• Verona Integron-Encoded Metallo-beta-lactamase (VIM): A less common carbapenemase in the United States but concerning because it can be resistant to even more antibiotics than KPC.
• Imipenemase (IMP): A less common carbapenemase in the United States but concerning because it can be resistant to even more antibiotics than KPC.
• Oxacillinase-48-like (OXA-48-like): A less common carbapenemase in the United States.

Laboratory Testing

To further improve surveillance and awareness of CRE, FDOH’s Bureau of Public Health Laboratories (BPHL) expanded CRE testing capabilities to identify types of resistance mechanisms used by organisms. Carbapenemase production is a resistance mechanism of concern. A carbapenemase is an enzyme that breaks down carbapenem antibiotics and can be transferred between organisms. A variety of carbapenemases have been reported in the U.S. and in Florida: Klebsiella pneumoniae carbapenemase (KPC), Verona integron-encoded metallo-beta-lactamase (NDM), and oxacillinase (OXA)-48-like.

All laboratories participating in ELR must report antimicrobial resistance testing results for all Acinetobacter baumannii, Citrobater species, Enterococcus species, Enterobacter species, Escherichia coli, Klebsiella species, Pseudomonas aeruginosa, Serratia species, and S. aureus isolates from normally sterile sites. Resistance results are process electronically in the state’s reportable disease surveillance system.

Streptococcus pneumoniae in 2019

• 760 S. pneumoniae invasive disease cases reported
• 40% had isolates resistant to at least one antibiotic
• 19% resistant to penicillin and 0% resistant to amoxicillin (recommended first-line antibiotics)

Staphylococcus aureus in 2019

• 58,368 isolates reported
• 38% resistant to oxacillin (i.e., MRSA) (susceptibility testing now done on oxacillin rather than methicillin)
• 0% resistant to vancomycin
  (recommended first-line antibiotic when resistant to oxacillin)

Acinetobacter species in 2019

• 511 isolates reported
• 11% resistant to one or more carbapenems (doripenem, ertapenem, imipenem, meropenem)
• 10%-13% resistant to recommended antibiotics: cefepime, ceftazidime, ampicillin/ sulbactam

Escherichia coli in 2019

• 20,957 isolates reported
• 0.2% resistant to one or more carbapenems (i.e., CRE)
• <1% resistant to imipenem or meropenem
  (recommended first-line antibiotics)

Klebsiella species in 2019

• 5,918 isolates reported
• 0.8% resistant to one or more carbapenems (i.e., CRE)
• <1% resistant to imipenem or meropenem
  (recommended first-line antibiotics)

Enterobacteriaceae in 2019

• 28,166 isolates reported
• 0.6% resistant to carbapenem (i.e., CRE)