HealthCare Associated Infections Flashcards
What Is a Healthcare Associated (HAI) Infection?
Infections that can occur when patients are receiving treatment in:
- Hospitals
- Care Homes
- Surgical Centers
What are the 2 Types of HAI?
Endogenous infection:
Infection occurring within the patient
e.g. C. albicans (Oral Thrush)
Exogenous Infection:
Infection originating from outside the body
e.g. Aspergillus fumigatus
How Do HAI occur?
- Overusing Antibiotics
- Invasive Devices
- Inappropriate care of open wounds
- Mechanical ventilation
Describe Skin, Tissue and Surgical Site Infections.
Common Organism: S. Aureus
How it occurs:
- Nurses/doctors are carriers
- Acquired from unsterilized equipment
Symptoms (Visible):
- Red Skin
- Pus Around wounds
Samples Taken with Swabs from Skin/Surgical Sites
What Are the Characteristics Of S. Aureus?
- Gram+ Cocci
- β-Haemolytic on Blood Agar
3, Catalase Positive (Break down Hydrogen
Peroxide into Oxygen + Water)
- Facultative anaerobe (able to adapt to
Anaerobic/Aerobic Environments)
What Is S. aureus Capable Of?
✓ Colonize Host (using Microbial Surface
Components Recognizing Adhesive Matrix
Molecules (MSCRAMMS)
✓ Invade Tissues
✓ Evade Host defenses (Protein A binds lgG Ab
upside down)
✓ Damage Host by producing invasins +
exocellular toxins
✓ Acquire Resistance to Antibiotics
What is Methicillin Resistant Staphylococcus Aureus (MRSA)?
Known as a ‘super bug’
Methicillin:
β-lactam Antibiotic used against β-lactamase producing S.aureus
How Does S. Aureus become MRSA?
- Methicillin Resistance in S. aureus due to
Staphylococcal Cassette Chromosome mec (SCCmec) - Transfer done via horizontal gene transfer
e.g. Transduction/Conjugation - SCCmec carries mecA gene (or variants) = Encodes
PBP2aPBP2: Modified Enzyme, has low affinity for β-lactam
Antibiotics - ISCCmec integrates into attachment site on
S. aureus chromosome
mediated by Recombinase Enzymes encoded within
SCCmec - Integration ensures stable Inheritance of
mecA gene across Bacterial Generations - mecA gene transcribed + translated into
PBP2a protein - PBP2a not inhibited by β-lactam antibiotics
(e.g., methicillin, penicillin) - PBP2a assumes role of cell wall synthesis,
allows bacteria to survive, despite antibiotic
exposure
Explain Urinary Tract Infections (UTIs).
Common cause: E. Coli
How it Occurs:
- incorrect wiping of stool
- Improper sterilization of catheters
- Catheter: Tube used to Remove Bodily Fluids
Symptoms/Clinical Manifestation:
- Cloudy Urine
- Frequent need to Urinate
- Pain while Urinating
What are The Characteristics of E. Coli?
Key Characteristics
- Gram-
- Catalase+
- β-Haemolytic on Blood Agar
- Peritrichous Flagella
(Flagella Distributed all over its cell surface) - Facultative Anaerobes
(Can grow with/without Oxygen by switching
metabolic pathway)
Many strains: Harmless
Common cause of: Food Poisoning
Risk High For:
- Immunocompromised Patients
- Elderly Individuals
- Patients on Antibiotics
How Do Bloodstream Infections Occur?
Common Organism: E. Coli + S. Aureus
How It Happens:
- UTIs can Spread from bladder to kidneys
and into the bloodstream - Skin + Tissue infections can be deep set and
enter bloodstream - Needle Stick Injury
Symptoms:
- Low Body Temp
- Fatigue
- Fast Heartbeat
Explain Gastrointestinal (GI) Infections.
Common cause: C. difficile
How it happens:
contact with a carrier
Symptoms:
- Stomach cramps
- Watery Diarrhea
- Weight Loss
What Are Some Characteristics of C. difficile?
- Gram+ Bacillus
- Anaerobic
- Spore Forming
- Non-Haemolytic (γ)
- Glossy/Grey Coloured
How Does C. difficile Infect?
Colonizes healthy Individuals, does not cause infection
Infection only happens in high risk individuals
Releases Toxins A+B for infection
Toxin B: Most Virulent
How Can the Chain Of Infection be Broken?
Reservoirs
1. Sterilizing Equipment
2. Reduce Visitors
Portal Of Exit
1. Wear Correct PPE
2. Hand Washing
Means Of Transmission
1. Change Gloves
2. Food Prepared Correctly
Portal Of Entry
1. Monitor changes in wounds
2. Post-surgical swabs
How Can The Chain Of Infection Be Broken By Identify Susceptible Hosts?
By Taking Swabs From:
- Nose
- Mouth
- Throat
- Groin
- Rectum
By Testing Patients:
- Before Surgery
- Admitting patients to wards
- If they had catheters used on them
- MRSA Outbreaks
