Infection S4 (Done) Flashcards
What are healthcare infections?
Infections arising as a concequence of providing healthcare that are:
- Not present nor incubation at admission (onset 48hrs after admission)
- Found in patient, visitors and healthcare workers
Give some common examples of infections due to medical practice
Surgical site infection
Central line associated bloodstream infection
Ventilator associated pnuemonia
Catheter associated UTI
Clostridium difficile Infection
Give some examples of common viruses that cause HAI
Hep B, C
HIV
Norovirus
Influenza
Chickenpox
Give some examples of common bacteria that cause HAI
Staph aureus
C. difficile
E. coli
Klebsiella pnuemoniae
Pseudomonas aeruginosa
Mycobacterium tuberculosis
Give some common examples of fungi causing HAI
Candida albicans
Aspergillus spp.
Give an examples of a common parasite that can cause HAI
Malaria
What patient factors predispose to HAI?
Extremes of age (young/old)
Obesity/malnourishment
Cancer
Immunosuppression
Smoker
Surgical patient
Emergency admission
What are the 4 Ps of infection control?
Patient
Pathogen
Practice
Place
What are the patient factors contributing to infection control?
General and specific patient risk factors
Interactions with:
- Other patients
- Healthcare workers
- Visitors
what are the pathogen factors relevant to infection control?
Virulence factors
Ecological interactions:
- Other microbes
- Antibiotics/disinfectants
What are the healthcare environment factors relevant to infection control?
Activities of HCWs directly related to treatment
Policies and their implementation
Organisational structures
Regional and national political initiatives
Leadership from ward to government
What are the general interventions aimed at reducing patient’s risk of acquiring a healthcare infection
Optimise condition (Smoking, nutrition, diabetes)
Antimicrobial prophylaxis
Prevention of commensal spread:
- Skin preparation
- Hand hygiene
What are the more specific/targetted interventions aimed at reducing patient risk of HAI?
MRSA screening
Mupirocin nasla ointment (Prevent aerosol spread of infection)
Disinfectant body wash
Give some examples of how we might halt patient to patient spread of infection?
Isolation of infected/susceptible patients:
- Separate rooms
- Positive pressure in rooms
- Air filtration
How do we prevent spread of HAI from healthcare workers?
Disease free and vaccinated staff
Good practice:
- Sterile non-touch techniques
Hand hygiene
Personal protection equipment (Face masks, aprons, gloves)
Antimicrobial prescribing to HCPs
What are the environmental interventions to prevent patient infection from water and food?
Appropriate kitchen and ward food facilities
Food food hygiene (sterile food)
What are the environmental interventions that can prevent infection of patients from surfaces?
Cleanliness of built environment:
- Toilets
- Wash hand basins
- Furniture
Cleaning:
- Disinfectant
- Steam cleaning
- H2O2 vapour
Medical devices:
- Single use equipment
- Sterilisation
- Decontamination
How can ward layout affect HAI?
Overcrowding of bed put patients in closer proximity, aiding spread of infection
How is diagnoses of necrotising fasciitis made?
Suspicision of deep seated infection in an acutely unwell patient supported by relevant labs (WBC, CRP etc)
Surgical exploration to confirm
What are the common features of someone with a necrotising fasciitis infection?
Extreme pain in infected area
High temp, pulse
Hypotensive
Raised WBCs
How might we manage a patient with necrotising fasciitis?
Supportive care (Fluid resus)
Analgesia
Antibiotics
Surgical/ITU referral
Describe the surgical management of necroising fascitis?
Initial fasciotomy
Assesment of deep tissue (may require debridement)
May require amputation
Skin grafting if patient survives
What factors influence our choice of antibiotic when treating an infection?
Severity
Site
Likely pathogens
Route of administration
Adverse affects:
- Allergy/reaction*
- Interactions with other drugs*
- Renal/hepatic impairment*
What are the likely pathogens of necrotising fasciitis infection?
Group A Beta-haemolytic streptococci (E.g. Strep. pyogenes
What is the gram stain appearance of Streptococci?
G+
Describe the different types of streptococcal haemolysis
Give examples of species of each type
Alpha:
Oxidise iron turning dark green in culture
S. Pneumoniae
Beta:
Completely rupture blood cells
S. Pyogenes
Gamma:
Non-haemolytic
Give an example of a non-haemolytic cocci
Enterococcus Faecalis
Describe the pathogenesis of streptococci
Hint: Give toxin/structure and its effect
M proteins:
Component of cell wall
Antiphagocytic
Exotoxins:
Pyrogenic exotoxins (Superantigens) - Cause rash
Streptolysin O and S (Cell lysis)
Streptokinase:
Lysis of clots
Streptodornase:
DNAase promoting spread of infection
C5a peptidase:
Inactivation of complement
What antibiotics are used to treat Streptococcal infection?
B-lactams and glycopeptides
Some macrolides and tetracyclines
How might we directly target toxin mediate disease as a result of infection?
Anti-toxin therapy:
High dose human Ig
Interfere with toxin synthesis:
Antibiotics that target protein synthesis (E.g. Clindamycin, Rifampicin)
Give the specifics of necrotising fasciitis antibiotic treatment
Empiric:
Tazocin + Clindamycin
If group A Beta-haemolytic Streptococci (GAS) identified:
Tazocin + Benzylpenicillin
Consider adding high dose Ig
Give some other diseases caused by Group A Beta-haemolytic streptococci (GAS)
Acute pharyngitis/tonsilitis (With rash = scarlet fever)
Impetigo
Puerperal sepsis
Give 2 post-streptococcal infection sequelae
How does each come about?
Acute rheumatic fever (2-3 wks post):
Cross reaction between heart/joint tissues and strep antigens (esp M protein)
Acute glomerulonephritis (1 wk post):
Antigen-antibody complexes on basement membrane of glomerulus post infection
Give examples of conditions caused by Alpha-haemolytic streptococci (Viridans)
Infective endocarditis
Pneumonia, Meningitis (S. Pneumoniae)
Give possible infections caused by Gamma-haemolytic ‘streptococci’
Enterococcus Faecalis - Abdo sepsis, UTI
What are the clinical signs of scarlet fever?
Erythematous blanching rash
Circumoral pallor
Strawberry tongue
Tonsilitis/Pharyngitis (sore throat, fever)
Give some exampes of common staphylococcal infections
Impetigo
Furuncles (boils - E.g. facial ‘spots’)
Surgical wound infections
What is impetigo?
Give two common causative organisms
Skin infection
Symptoms:
Red rash
Develops into sores that leak pus/fluid
Can cause fluid flilled blisters (Mostly in under 2s)
Organisms:
Staph. aureus
Strep. pyogenes
What is the appearance of staphylococci after gram staining?
G+
What is the coagulase test and what organisms does it differentiate?
Differentiation:
Tests staphylococci spp for presence of coagulase enzyme (Converts fibrinogen to fibrin)
Staph aureus is coagulase positive
Most others are coagulase negative
Testing:
Done on a slide or in a tube
Involves inoculation of plasma with staphylococcus organisms
What are the common antibitoics used against staphylococcus spp.?
Hint: Remember resistance
Flucloxacillin:
Resistant to staphylococcus B-lactamase
Some cephalosporins
Some B-lactamase/B-lactamase inhibitor combos:
Co-amoxiclav, Tazocin
Glycopeptides:
Vancomycin
Often in MRSA infection
Describe the pathogensis of C. diff
Enterotoxin (C. diff toxin A):
Increases Cl- channel permeability in the mucosal cells of gut lumen (intestines)
Secretory diarrhoea results
Cytotoxin (C. diff toxin B):
Causes actin depolymerisation
Overall:
Infection leads to Dairrhoea and Intestinal inflammation
How is the severity of C diff infection assessed?
Severe infection (Any of below):
- Sepsis or temp = >38.3C
- Albumin < 25g/l, WBC > 15 x 109/L, elevated creatinine (>50% above baseline)
- Signs of severe colitis or pseudomembranous colitis
What antibiotics are reccomended for treatment of C. diff?
Non-severe = Metronidazole
Severe = Vancomycin + Metronidazole (if vancomycin underwhelming in effect)
What are the concequences of norovirus infection?
Viral gastroenteritis:
Vomitting
Diarrhoea
Dehydration
How should a patient with norovirus be treated on the ward?
Isolated
PPE used by healthcare workers
Sterile/non-touch technique for all procedures where possible
Disinfection of area (Chlorine based)
