Lecture 5.1 - Hospital acquired infections
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Questions and Answers

What is the primary mechanism of antibiotic resistance in Methicillin-resistant Staphylococcus aureus (MRSA)?

  • Alteration of target binding site
  • Reduced drug accumulation
  • Production of beta-lactamase
  • Genetic mutation coding for PBP2a (correct)
  • Which of the following is a common route of transmission for norovirus?

  • Airborne transmission
  • Faecal-oral route (correct)
  • Direct contact with infected individuals
  • Vector-borne transmission
  • What is the primary goal of infection control measures in preventing the spread of Clostridium difficile?

  • Reducing the transmission of spores (correct)
  • Eradicating the bacteria from the environment
  • Treating infected individuals
  • Enhancing the immune response
  • Which of the following is a risk factor for rotavirus infection?

    <p>Children under 5 years old</p> Signup and view all the answers

    What is the primary treatment option for Clostridium difficile infection?

    <p>Antibiotics</p> Signup and view all the answers

    Which of the following is a prevention strategy for Methicillin-resistant Staphylococcus aureus (MRSA)?

    <p>Screening and isolation</p> Signup and view all the answers

    What is the primary mechanism of action of Toxin A and Toxin B in Clostridium difficile infection?

    <p>Stimulating the inflammatory response</p> Signup and view all the answers

    Which of the following is a characteristic of norovirus infection?

    <p>Nausea, vomiting, and watery diarrhoea</p> Signup and view all the answers

    What is the minimum colony forming unit (CFU) per milliliter required to confirm a urinary catheter associated infection?

    <p>10^3</p> Signup and view all the answers

    Which of the following organisms is NOT a multidrug resistant enterobacteriaceae (MDRE)?

    <p>Staphylococcus aureus</p> Signup and view all the answers

    What is the primary purpose of hand hygiene in preventing catheter associated UTI?

    <p>To prevent infection transmission from the healthcare worker to the patient</p> Signup and view all the answers

    Which of the following is a risk factor for catheter associated UTI?

    <p>Catheter insertion for longer than 48 hours</p> Signup and view all the answers

    What is the primary mechanism of antibiotic resistance in bacteria?

    <p>Inactivation of antibiotic</p> Signup and view all the answers

    Which of the following is a prevention strategy for catheter associated UTI?

    <p>Evaluation of catheter need prior to insertion</p> Signup and view all the answers

    What is the term used to describe the ability of a microbe to resist the effects of medication that once could successfully treat the microbe?

    <p>Antimicrobial resistance</p> Signup and view all the answers

    Which of the following is a multidrug resistant organism of concern?

    <p>Methicillin-resistant Staphylococcus aureus (MRSA)</p> Signup and view all the answers

    What is the primary route of infection transmission for ventilator-associated pneumonia (VAP)?

    <p>Micro aspiration of oropharyngeal pathogens around the cuff</p> Signup and view all the answers

    Which of the following is NOT a predisposing factor for hospital-acquired infections (HAIs)?

    <p>Young age</p> Signup and view all the answers

    What is the primary goal of the VAP bundle?

    <p>To reduce the risk of ventilator-associated pneumonia</p> Signup and view all the answers

    Which of the following organisms is MOST commonly associated with catheter-related bloodstream infections (CRBSIs)?

    <p>Staphylococcus epidermidis</p> Signup and view all the answers

    What is the primary mechanism of infection transmission in surgical site infections (SSIs)?

    <p>Contamination of the surgical site during surgery</p> Signup and view all the answers

    Which of the following is a recommended prevention strategy for surgical site infections (SSIs)?

    <p>Chlorhexidine washes/shower prior to surgery</p> Signup and view all the answers

    What is the primary goal of surveillance for surgical site infections (SSIs)?

    <p>To monitor the effectiveness of prevention strategies</p> Signup and view all the answers

    Which of the following is a recommended infection control measure for catheter-associated urinary tract infections (CAUTIs)?

    <p>Limiting the duration of urinary catheter use</p> Signup and view all the answers

    What is the primary reason why hospital-acquired infections (HAIs) are a significant health and economic burden?

    <p>All of the above</p> Signup and view all the answers

    Which of the following is a common complication of ventilator-associated pneumonia (VAP)?

    <p>Acute respiratory distress syndrome (ARDS)</p> Signup and view all the answers

    Study Notes

    Mechanisms of Antimicrobial Resistance

    • Alteration of target or binding site
    • Alteration of metabolic pathway to prevent formation of proteins or alter DNA
    • Reduced drug accumulation

    Emergence of Resistance in Staphylococci and Gram Positive Bacteria

    Methicillin Resistant Staphylococcus Aureus (MRSA)

    • Refers to a group of gram-positive bacteria that are genetically distinct from other strains of staphylococcus aureus
    • mecA gene codes for PBP2a which has low affinity for beta lactam antibiotics
    • Prevention: screening, handwashing, isolation
    • Management: antibiotics (vancomycin), dependent on site of infection

    Norovirus

    • Non-enveloped, ss +ve strand RNA virus
    • Spread by faecal-oral route
    • Characterised by: nausea, vomiting, watery diarrhoea, abdominal pain, and in some cases, loss of taste
    • Symptoms develop 12-48 hours after exposure
    • General lethargy, weakness, muscle aches, headaches, and low-grade fevers may occur
    • Most people make a full recovery within 2-3 days

    Rotavirus

    • Non-enveloped ds RNA virus
    • Considered the most important viral agent of acute gastroenteritis worldwide in children less than 5
    • Vaccines available for prevention
    • Symptoms occur 48 hours after admission to 72 hours after hospital discharge

    Clostridium Difficile (Clostridioides Difficile)

    • Gram positive spore forming rods
    • Pathogenic strains produce toxic polypeptides Toxin A and Toxin B
    • Toxin A and Toxin B: exotoxins stimulating the inflammatory response, enterotoxins causing gastrointestinal symptoms
    • Symptoms: watery diarrhoea, fever, nausea, and abdominal pain
    • Urinary catheter associated infections: defined as an infection occurring 48 hours after insertion, signs and symptoms of infection, and a positive urine culture of greater than 10^3 cfu/ml

    Causative Organisms

    • Multidrug resistant enterobacteriaceae (MDRE): Escherichia coli, Klebsiella, Proteus, and Pseudomonas species (gram-negative)
    • Candida albicans

    Prevention of Catheter Associated UTI

    • Evaluation of catheter need prior to insertion
    • Hand hygiene immediately before and after manipulation of the catheter site
    • Closed catheter system
    • Catheter securement system
    • Urinary collection bag not to be higher than the bladder
    • Regular emptying of the collecting bag

    Multiresistant Organisms

    • Bacteria that have become resistant to many antibiotics
    • Examples: Methicillin resistant staphylococcus aureus (MRSA), Vancomycin resistant Enterococci (VRE), Multidrug resistant Enterobacteriaceae (MDRE)

    Antimicrobial Resistance

    • Ability of a microbe to resist the effects of medication
    • Factors to consider: duration of antibiotics, use of broad spectrum antibiotics, hygiene

    Principles of Antibiotic Resistance

    • Inactivation of antibiotic (e.g. beta-lactamase)

    Hospital Acquired Infections (HAI)

    • Infections arising as a consequence of providing healthcare
    • Neither present nor incubating at time of admission (onset is at least 48 hours after admission)
    • Includes infections in hospital visitors and healthcare workers
    • NHS England defines probable healthcare-associated COVID-19 inpatient infection as patients diagnosed more than 7 days after admission

    Consequences

    • Major health and economic burden (8% of inpatients)
    • Results in increase in: length of hospitalisation, morbidity, cost of care, mortality
    • Highest prevalence of HAIs: generally in ICU
    • Preventable

    Types of Infections

    • HAIs can be classified into six main types which account for 80% of all HAIs:
      • Respiratory tract infections (pneumonia/other respiratory infections) - 22.8%
      • Urinary tract infections - 17.2%
      • Surgical site infections (SSI) - 15.7%
      • Clinical sepsis - 10.5%
      • Gastrointestinal infections - 8.8%
      • Bloodstream infections - 7.3%

    Infection Transmission

    • Routes of entry of microbes: skin, gastrointestinal, respiratory, urogenital, person to person transmission (respiratory/faecal-oral)

    Predisposing Factors in Patients

    • Extremes of age
    • Obesity/malnourished
    • Diabetes
    • Cancer
    • Immunosuppression
    • Smoker
    • Surgical patient
    • Emergency admission
    • Prosthetic devices

    Organisms Causing Hospital Acquired Infections

    • Bacteria: staphylococcus aureus (including MRSA), Clostridium difficile, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa
    • Viruses: blood borne viruses (hepatitis B and C, HIV, Norovirus, Rotavirus, SARS-CoV-2)
    • Fungi: Candida Albicans, Aspergillus species
    • Parasites: Cryptosporidium spp

    Ventilator Associated Pneumonia (VAP)

    • Pneumonia develops in 5-20% of mechanically ventilated patients
    • Mortality of ventilator associated infection: 10%
    • Associated complications: pulmonary ARDS, pneumothorax, pulmonary oedema

    Pathogenesis of VAP

    • Micro aspiration of oropharyngeal pathogens around the cuff
    • Micro aspiration of gastro-enteric regurgitated secretion
    • Bio film within the endotracheal tube
    • Cross contamination via respiratory equipment

    Ventilator Associated Pneumonia

    • Causative pathogens: EARLY (5 days of being off ventilator) - MRSA, Pseudomonas species, multi-drug resistant organisms

    VAP Bundle

    • Elevation of the head of the bed 30 degrees to prevent aspiration
    • Sedation holiday to check for continued ventilation needs
    • Weaning trials to indicate if the ventilator is still needed daily
    • Medication to prevent gastrointestinal bleeding
    • DVT prophylaxis
    • Sub-glottal suctioning to prevent colonisation and infection from pooling of secretions
    • Oral care to prevent accumulation of oral bacteria
    • Introduction to skin pathogens at the time of insertion
    • Contamination of the catheter hub(s)
    • Contaminated infusate
    • Migration of skin pathogens into the cutaneous catheter tract
    • Hematogenous seeding from a distant infectious focus
    • Most common pathogens: S.epidermis, S.aureus, Candida albicans

    Prevention Measures

    • Fill out central line insertion check list
    • Hand hygiene prior to insertion
    • Use standardised supply kit
    • Use maximal barrier precautions
    • Clean skin with chlorhexidine and allow to air dry
    • Need for continuation of catheter is evaluated daily
    • Central line dressings are changed every 7 days
    • Positive pressure caps are used on all central line ports and changed every 7 days

    Surgical Site Infections (SSI)

    • Most common HAI in surgical patients
    • Superficial incisional SSI: skin + subcutaneous tissue
    • Deep incisional SSI: deep soft tissue (fascia + muscle)
    • Organ/space SSI: organs, body cavities, sub-integumental spaces
    • Occur within 30 days post-op, or within 1 year if an implant is left, and infection appears to be related to the operation
    • Most SSIs occur between 5-10 days post-operation

    Organisms Causing SSI

    • Enterobacterales: caused SSI are the most prevalent in large bowel surgery
    • Infecting organisms in hip and knee surgery: Methicillin sensitive staphylococcus aureus, Methicillin resistant staphylococcus aureus, Coagulase-negative staphylococci
    • Infections can also be caused by a mixture of organisms

    Prevention Measures

    • Screened prior to surgery for MRSA
    • Chlorhexidine washes/shower
    • Alcohol containing skin prep
    • Preoperative antibiotics
    • Appropriate hair removal
    • Euglycemia
    • Optimise tissue oxygenation
    • Wound care
    • Best practice checklist
    • Surveillance for SSI
    • Educate providers, patient regarding SSI

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    Description

    Explore the mechanisms of antimicrobial resistance in bacteria, including alteration of target sites, metabolic pathways, and drug accumulation. Learn about the emergence of resistance in Staphylococci and Gram Positive Bacteria, including Methicillin Resistant Staphylococcus Aureus (MRSA).

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