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)
- Klebsiella PneumoniaeCarbapenemase (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