Lecture 33 - Diagnosis, Treatment and Prevention of Infections Flashcards
Bacteria examples
Staphylococcus aureus
Streptococci
Escherichia coli
Tuberculosis
Examples of viruses
Rhinovirus (common cold)
Influenza
Hepatitis B/C
HIV
Examples of fungi
candida
tinea
Examples of parasites
malaria
hookworm
What are the sources of infection and routes of transmission
endogenous flora -patients themselves environment -inside: healthcare facilities outside: soil, water/food -other people unwell contact colonised contact eg. healthcare workers with MRSA Animals/insects
History of infections will indicate what type of symptoms?
non-specific symptoms
- fever
- sweat, chills, fever
- rigors
- loss of apetite, aching muscles
specific symptoms
- according to source
- pneumonia - cough, breathlessness, sputum
- meningitis - headache, neck stiffness, photophobia
What conditions make people more susceptible to infection
Past medical history: diabetes, immunodeficiency e.g. HIV
Drug history: steroids, chemotherapy
What sort of lifestyle activities make people more prone to infection?
Occupation: healthcare worker, vet, farmer, sex worker
Travel: ask where, when and what did they get up to…?
Recreation: hobbies (e.g. watersports), food (e.g. takeaways/BBQ), injecting drugs
Contacts: people (including sexual partners), animals, insects
WBC tests than indicate infection
neutrophils elevated in bacterial infections - pneumococcal pneumonia
Lymphocyte elevated in virals - glandular fever
eosinophils elevated in parasitic infections - schistosomiasis
basic tests showing infection
C-reactive protein (CRP) – marker of inflammation
U&E – urea and electrolyte levels (kidney function)
LFT – liver function tests
What to send to the lab
body/tissue fluid
blood/urine culture
pneumonia - sputum
gastroenteritis - faeces
-tonsilitis - throat swab
Importance about taking samples
should be sent before treatment starts
when taking blood cultures - use asceptic technique to clean skin
what procedure do you use to test meningitis
lumbar puncture - test CSF
How do we detect organisms that we can’t grow in the laboratory?
Identify part of the organism Proteins DNA/RNA (by Polymerase Chain Reaction) Identify body's immune response to infection Antibodies: IgM IgG
Examples of antigen testing
Legionnaire’s disease (pneumonia): urine test
Rapid Hepatitis B: blood test
what is PCR
DNA/RNA identification
method of detecting genetic fingerprints identifies unique genetic code sequence for infection Meningitis HIV Hepatitis B and C Respiratory viruses (e.g. influenza)
Antibody testing
IgM
Initial antibody response
Appears within a week, usually disappears after a few months
IgG
Later antibody response
Appears 10-14 days
Test for rising level (titre) in consecutive samples
Persists throughout life (part of immunological memory)
Also useful to test whether you are immune to an infection
Treating infections
supportive therapy
symptomatic - paracetamol
dehydration/low BP - iv fluids
specific therapy
- antimicrobials
- antibiotics
virals have no specific treatment
where is penicillin derived from
antibiotic
derived from a mould
Where is mupirocin derived from
produced from pseudomonas fluorescens bacterium
What do we ideally want an antimicrobial to do?
selective toxicity bacteriocidal no resistance good pharmacokinetics no side effects not activated by enzymes
What are the problems with anti-microbials
Variable spectrum of activity Broad - kills lots of organisms narrow - kills few some cannot be given orally cause side effects -allergy bacterial resistance eg MRSA
Reducing pathogens in environment
general:
Clean drinking water
Improving sanitation
Hygienic food preparation
in hospital:
Cleaning wards, rooms and equipment
Filtered air in operating theatres
Using sterile instruments when operating, taking blood etc.
How to protect the potential host?
prophylactic treatments
-anti-malarials
antibiotics - give to very immunosuppressed patients
Immunisation
passive - chickenpox immunoglobulin
active - by stimulating immune system with something which mimics the infection
eg. hepatitis B virus surface antigen
Notification of communicable diseases
From Bacillus anthracis (anthrax) to Yersinia pestis (plague)
