Drug Resistance

Antimicrobial Resistance

  • Definition: A microorganism is considered resistant if its replication cannot be stopped by two or more antibiotics, either sequentially or simultaneously.

  • Microorganisms:

    • Methicillin-resistant Staphylococcus aureus (MRSA)

    • Vancomycin-resistant Enterococcus (VRE)

    • Carbapenem-resistant Enterobacteriaceae (CRE)

    • Multidrug-resistant organisms (MDROs)

    • Clostridium difficile (C. diff)

    • Extended-Spectrum Beta-Lactamase (ESBL) producing bacteria

Mechanism of Drug Resistance

  • Pathogens develop specific genes to:

    • Survive longer or grow faster than standard treatments.

    • Process includes:

      • Maturation leading to adaptation

      • Antibiotics destroying sensitive bacteria, leaving insensitive (mutated) bacteria to multiply with reduced competition.

  • Four basic mechanisms:

    • Decrease the concentration of a drug at its site of action.

    • Alter the structure of drug target molecules.

    • Produce a drug antagonist.

    • Cause drug inactivation.

  • Factors:

    • Use of antibiotics when fever's cause is unproven.

    • Improper dosages.

    • Omission of necessary surgical drainage.

    • Overprescribing antibiotics for non-bacterial infections.

    • Employment of inappropriate antibiotics for the actual infecting microorganism.

    • Incomplete courses of prescribed antibiotics.

Methicillin-Resistant Staphylococcus aureus (MRSA)

  • Definition: S. aureus that does not respond to methicillin or other penicillin-based drugs.

  • Types:

    • Hospital-Acquired MRSA:

      • Spread through

        • Indwelling urinary catheters

        • Vascular access devices

        • Open wounds

        • Endotracheal tubes

      • Treatable with IV vancomycin and oral linezolid

Community-Associated MRSA (CA-MRSA)

  • Definition: S. aureus infection occurring in healthy, non-hospitalized individuals that does not respond to methicillin or other penicillin-based drugs.

  • Prevention:

    • Perform frequent hand hygiene (use of hand sanitizers).

    • Avoid close contact with individuals having infectious wounds.

    • Stay away from crowded places and contaminated surfaces.

    • Emphasize good overall hygiene.

    • Importance of health teaching in community settings.

Vancomycin-Resistant Enterococci (VRE)

  • Definition: Enterococci that are resistant to the antibiotic vancomycin.

  • Common cause of urinary tract infections.

  • Newer antibiotics available for treatment.

Extended-Spectrum Beta-Lactamase (ESBL)

  • Definition: Enzymes produced by bacteria such as E. coli and Klebsiella.

  • Resistance to:

    • Penicillins

    • Cephalosporins

    • Monobactams

  • Treatment Options:

    • Carbapenems

    • Fluoroquinolones

Carbapenem-Resistant Enterobacteriaceae (CRE)

  • Definition: Resistant to carbapenem antibiotics due to carbapenemase enzymes.

  • Difficulty in treatment due to limited antibiotic options.

  • Recognized as an emerging global health threat.

Prevention and Control Measures: Nurse's Role

  • Promote proper hand hygiene:

    • Use alcohol-based hand sanitizer (e.g., Purell)

    • Use soap and water for spores (e.g., C. diff).

  • Prevention of pathogen spread to others, healthcare workers, and the environment.

    • Challenges: Resistant infections can cause serious complications.

  • Implement precautions:

    • Use gowns, gloves, and masks.

    • Utilize dedicated equipment and ensure proper cleaning.

    • Apply contact precautions for infected patients.

    • Follow transmission-based precautions which include staff and patient placement and cohorting.

    • Ensure judicious use of antibiotics.

    • Engage in surveillance and reporting of infections.

Transmission-Based Precautions Chart

Airborne:

  • Tuberculosis

  • Measles

  • Varicella

  • Disseminated herpes zoster

  • Multidrug-resistant adenovirus

  • Respiratory syncytial virus (RSV)

Droplet:

  • MRSA

  • VRE

  • ESBL

  • Influenza A or B

  • Meningitis

  • Pertussis

  • RSV

  • Mumps

  • Rubella

Contact:

  • Lice

  • Scabies

Challenges for the Future

  • Increasing antibiotic resistance and limited treatment options present a significant challenge.

  • Urgent need for new antibiotic development and research.

  • Importance of prevention and responsible antibiotic use cannot be overstated.