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Questions and Answers
What is the primary mechanism of antibiotic resistance in Methicillin-resistant Staphylococcus aureus (MRSA)?
Which of the following is a common route of transmission for norovirus?
What is the primary goal of infection control measures in preventing the spread of Clostridium difficile?
Which of the following is a risk factor for rotavirus infection?
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What is the primary treatment option for Clostridium difficile infection?
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Which of the following is a prevention strategy for Methicillin-resistant Staphylococcus aureus (MRSA)?
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What is the primary mechanism of action of Toxin A and Toxin B in Clostridium difficile infection?
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Which of the following is a characteristic of norovirus infection?
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What is the minimum colony forming unit (CFU) per milliliter required to confirm a urinary catheter associated infection?
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Which of the following organisms is NOT a multidrug resistant enterobacteriaceae (MDRE)?
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What is the primary purpose of hand hygiene in preventing catheter associated UTI?
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Which of the following is a risk factor for catheter associated UTI?
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What is the primary mechanism of antibiotic resistance in bacteria?
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Which of the following is a prevention strategy for catheter associated UTI?
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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?
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Which of the following is a multidrug resistant organism of concern?
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What is the primary route of infection transmission for ventilator-associated pneumonia (VAP)?
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Which of the following is NOT a predisposing factor for hospital-acquired infections (HAIs)?
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What is the primary goal of the VAP bundle?
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Which of the following organisms is MOST commonly associated with catheter-related bloodstream infections (CRBSIs)?
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What is the primary mechanism of infection transmission in surgical site infections (SSIs)?
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Which of the following is a recommended prevention strategy for surgical site infections (SSIs)?
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What is the primary goal of surveillance for surgical site infections (SSIs)?
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Which of the following is a recommended infection control measure for catheter-associated urinary tract infections (CAUTIs)?
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What is the primary reason why hospital-acquired infections (HAIs) are a significant health and economic burden?
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Which of the following is a common complication of ventilator-associated pneumonia (VAP)?
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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
Catheter Related Blood Stream Infections
- 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).
