Multidrug-resistant organisms (MDROs)

Pathogens (usually bacteria) that are resistant to ≥ 1 antimicrobial agent.

• Prolonged hospitalization, especially in the ICU

• Prior antibiotic use

• Indwelling medical devices

• Exposure to other individuals with MDROs (e.g., in long-term care facilities)

• Prior history of MDRO colonization or infection

• Forms a modified penicillin-binding protein (PBP) that inhibits binding of beta-lactam antibiotics, thereby decreasing their bactericidal effect.

• Modified PBPs are encoded by the mecA gene on the staphylococcal chromosome

• Epidemiology: asymptomatic colonization of the nasal mucosa estimated to affect 0.5–5% of the population

• Diseases: nosocomial and community-acquired infections

• Measures

  • Hygiene measures

    • Hand disinfection

    • Protective clothing (gown, mask)

    • Disinfection of patient rooms

  • Patient isolation (if necessary, cohort isolation)

  • MRSA eradication in asymptomatic carriers

    • Mupirocin nasal ointment

    • Antiseptic solution for skin/hair contamination (e.g., chlorhexidin

• Resistance: Bacteria produce beta-lactamases that have a broad spectrum and cleave penicillins, cephalosporins, and, in isolated cases, carbapenems.

• Pathogens: particularly gram-negative bacteria (e.g., Enterobacteriaceae such as Klebsiella spp., Escherichia coli)

• Diseases

  • Nosocomial urinary tract infections

  • Health care-associated pneumonia

• Measures: isolation in separate rooms required

• Definition: bacterial strains of the genus Enterococcus that are resistant to vancomycin (e.g., E. faecalis, E. faecium)

• Resistance: acquisition of van genes (e.g., through transposition of plasmid-encoded genes such as the vanA gene) → alteration of peptidoglycan synthesis pathway (e.g., due to change from the d-alanine-d-alanine amino acid sequence to d-alanine-d-lactate) → inhibition of vancomycin binding to peptidoglycan

• Definition: gram-negative pathogens that are resistant to at least three of the four main antibiotic classes

• Measures

  • Suspected cases: no isolation

  • Confirmed cases

    • Basic hygiene measures in low-risk areas are sufficient.

    • Isolation in risk areas (e.g., ICU, neonatology, hematology-oncology)

• Resistance: high natural resistance to antibiotics

• Diseases

  • Pneumonia

  • Severely infected wounds

  • Urinary tract infections

  • Otitis externa (swimmer's ear)

  • Keratitis