Cerberus visits Pittsburgh: A CRE Like No Other

In most discussions of antimicrobial resistance, the menace of carbapenemase-producing Enterobacteriaceae (CRE) is mentioned. This family of bacteria,  which includes E.coli and Klebsiella species, often cause hospital-acquired infections and are extremely difficult--if not impossible to treat.

The carbapenem class of drugs are, in many ways, the last line of resort and include the drugs: imipenem-cilastatin, meropenem, ertapenem, and doripenem. CRE employ one of 3 enzymes to inactivate this class of drugs:

  1. KPC: the most common mechanism in the US
  2. NDM-1: reported multiple times in the US and also linked to medical tourism in India
  3. OXA-48: only reported twice in the US

A team from the University of Pittsburgh led by Yohei Doi--who I am honored to have been a co-fellow with--recently reported Klebsiella pneumoniae isolated from a patient in Pittsburgh that produces both OXA-48 and NDM-1. The isolate also possessed mutations that conferred high level aminoglycoside resistance.

The patient was a woman initially hospitalized in India for a neurologic condition who was subsequently transferred to Pittsburgh for further care. Once in Pittsburgh, she bounced between the hospital and long term acute care facilities-- a common theme amongst patients who harbor pathogens such as this one. Fortunately, this pathogen was merely colonizing the patient's urinary system and not causing an overt infection meriting treatment.

This case highlights the fact that bacteria, who have dominated the earth for billions of years, are genetically very plastic and can possess several modes of resistance due to selection pressure from antibiotics, uptake of plasmids from other bacteria, or other reasons. Also, the fact that this patient had been hospitalized in India should serve to remind clinicians of the high prevalence of these resistant isolates in other countries (see this excellent review on medical tourism for more information).