L1 Intro to Medical Bacteriology Flashcards
Features of bacteria
- Small
- Unicellular
- Prokaryotic (no compartmentalisation)
- Diverse
- Ubiquitous
Bacteria being useful…
- Ecosystem
- Source of useful compounds
- Food production
Bacteria being bad…
- Used in destructive processes e.g. disease
- Food spoilage
- Biofouling and corrosion
What % of human diseases are caused by bacteria?
35% (538 species)
Infectious disease in today’s society
Top 3 deaths in industrial population were all bacterial infections, but medical intervention has improved this
Koch’s postulates
DEMONSTRATES CAUSE AND RELATION TO SPECIFIC DISEASES
- Microorganism must be present in every case of the disease (not within healthy animals)
- Microorganism must be isolated from diseased host and grown in pure culture
- Specific disease must be reproduced when a pure culture of microorganism is inoculated into healthy susceptible host
- Microorganism must be recoverable from experimentally infected host and shown to be identical to original causative agent
Types of bacteria in disease (3)
- Pathogenic: only a small %
- Opportunistic: only cause disease in predisposed conditions e.g. illness
- Non-pathogenic: don’t cause disease
Site of infection
Can be superficial or within body and is more common on certain sites e.g. skin compared to stomach
Why is it difficult to get specimen only from the body?
Provides colonisation resistance and includes numerous conditional pathogens
Endogenous infections
Result from microbiome initiating infection e.g. skin infection and UTIs
Exogenous infections
Coming from outside of the body e.g. during food poisoning
What is zoonosis?
When an infectious disease can be transmitted from animal to a human
Examples of zoonotic human pathogens
- Anthrax
- Campylobacteriosis
- E.coli
- Plague (Yersina pestis)
What organism causes Tuberculosis?
Mycobacterium tuberculosis
Where is Tuberculosis primarily an infection of?
Lungs
Symptoms of Tuberculosis
-Cough
-Chest pain
-Fever
-Weight loss
-Fatigue
(symptoms only shown in active infection - not in latent infection)
What does Tuberculosis lead to?
Granuloma formation (spherical bundle of immune cells aggregated)
Necrosis (cell death)
Fibrosis (tissue scarring)
Statistics about Tuberculosis
-1/3 world’s population are latently infected
-1/10 latent infections become active
-Untreated active kills 1/2
Increased transmission where reduced medical care and overcrowding
What organism is pneumonia caused by?
Streptococcus pneumonia’s
Symptoms of Pneumonia
- Cough
- Fever
- Chest pain
Consequences of pneumonia
O2 transport through alveoli is compromised and leakage of bacteria occurs into bloodstream
What is a major cause of human disease?
Synergy between viral and bacterial disease
e.g. influenza and bacterial pneumonia
HIV and TB
Influenza and bacterial pneumonia synergy
Viral disruption of bronchial and lung cells
HIV and TB synergy
HIV individuals are 800x more likely to develop active TB
Foodborne infection
Don’t 100% know definite numbers as majority aren’t reported:
1 million cases per year in UK
20,000 hospital admissions
500 deaths
Types of food borne bacterial disease
- Infectious: Campylobacter (zoonotic associated with poultry)
- Toxic mediated: driven by organism growing in food that we’ve eaten, ingesting heat stable toxin which causes effects
Methods of prevention and treatment of bacterial diseases
- disinfection/ sterilisation
- aseptic techniques
- decolonisation and prophylactic antibacterial
- vaccination
- antibacterial chemotherapy
- anti-toxin
- other e.g. surgery, electrolyte replacement
