II. Pathophysiology: General
-
Enterobacteriaceae are Facultative Anaerobic Gram Negative Rods and are common human pathogens
- Cause Meningitis, Pneumonia, peritonitis, cystitis and other bacteremia
-
Enterobacteriaceae are grouped into subtypes
- EKP: Escherichia coli, Klebsiella, Proteus
- ESP: Enterobacter (Aerobacter), Serratia, Providencia (often grouped with Proteus)
- SS: Salmonella, Shigella
- Other: Citrobacter (Escherichia freundii), Morganella, Yersinia, Erwinia
- Resistance conferred via enzymes known as Carbapenemases that degrade beta lactams (including Carbapenems)
- KlebsiellaPneumoniae Carbapenemase (KPC) is most common, with Prevalence 47 to 90% in U.S.
- Metallo-Beta-Lactamases (zinc containing) are more recently described
-
Carbapenem resistant organisms (Carbapenemase producers)
- Carbapenem-Resistant Klebsiella Pneumoniae (see below)
- Enterobacter
- Escherichia coli
III. Pathophysiology: Carbapenem-Resistant Klebsiella Pneumoniae
- Carbapenem-Resistant Klebsiella Pneumoniae (CRKP) is the first CRE (described in early 2000s)
- Klebsiella Pneumoniae Carbapenemase (KPC) is the most common Carbapenemase
- CRKP strains are resistant to multiple antibiotics
- Resistance to Aztreonam, Ceftazidime, Ciprofloxacin and Amikacin have all significantly increased
- Quinolone and Aminoglycoside resistance has also significantly increased
- Colistin and Tigecycline appear to still be active against most strains of CRKP
- Some strains are resistant to all known antibiotics
- Mortality rates for CRKP have approached 50%
IV. Risk Factors: Transmission of Carbapenem-Resistant Enterobacteriaceae (via fecal-oral route)
- Health care exposure
- Longterm Care facility (e.g. Nursing Home)
- Immunocompromised state (high risk)
- Recent Mechanical Ventilation
- Hemodialysis
- Intensive Care unit stay
- Recent Urinary Catheterization
- Recent antibiotic use
V. Management
- Antibiotics for mild CRKP infections
- Antibiotics for severe CRKP infections
- Other antibiotic options that may be effective against CRKP infections
- Polymyxin used in combination with other agents
- Aminoglycosides (e.g. Gentamicin, Amikacin)
- Colistin (polymyxin E)
- Ceftazidime-Avibactam
- Meropenem-Vaborbactam
- Plazomicin
- Eravacycline
VI. Complications
- Mortality with Carbapenem-Resistant Enterobacteriaceae (CRE) infections approaches 23%
- High antibiotic clinical failure rates
VII. Prevention: Healthcare Transmission of Carbapenem-Resistant Enterobacteriaceae (CRE)
- Hand Hygiene with waterless Alcohol-based hand rub before and after each patient
- Contact precautions with gowns and gloves when exposed to colonized or infected sites
- Decontaminate healthcare equipment
- Minimize invasive devices as much as possible (e.g. central venous catheters, Endotracheal Intubation, Urinary Catheters)
- Cohort infected patients in shared rooms, or better, in single rooms
- Lab should notify staff in a timely manner of CRE
- Practice antimicrobial stewardship and limit antibiotic use and duration to appropriate indications
- Review hospital culture results every 6-12 months to identify CRE
- Screen patients at risk for CRE and those in close proximity to patients positive for CRE
- Perianal or rectal cultures are best source of surveillance cultures
- Oral Gentamicin can be used to eradicate CRE in carriers
- Zuckerman (2011) Bone Marrow Transplant 46(9): 1226-30 [PubMed]
VIII. References
- Carvey and Glauser (2023) Crit Dec Emerg Med 37(11): 23-9
- Glauser (2014) Crit Dec Emerg Med 28(11): 2-10