Bacteria Flashcards
What is microbiology?
The study of microorganisms and their relationships with humans
How can microorganisms be classified?
- Cellular; bacteria, fungi, protozoa, parasites
- Acellular; viruses, prions
What are the general features of bacterial structures?
- Capsule
- Pilli
- Cell wall
- DNA (in circular chromosomes)
- Plasmids
- Ribosomes
- Flagellum
- Membrane cytoplasm
How can bacteria be classified?
-Gram positive
-Gram negative
-Gram stain unreliable
-Gram variable
Can be classified by shape and arrangement
What is the role of gram staining?
Used to differentiate from gram negative and positive bacteria.
Thick peptidoglycan layer in gram positive bacteria cell wall ensures it keeps purple colour when gram staining.
What are the sterile sites of the body?
- CNS
- Blood, tissues and organ systems
- Lower respiratory tract
- Sinuses, inner and middle ear
- Renal system and down to posterior urethra
- Eye
- Female reproductive tract down to cervix
What are the areas of body colonised by bacteria?
- Nose
- Throat
- Mouth
- Skin
- Large intestine
- Vagina
- Urethra
What is colonisation?
Describes when bacteria grow on body sites exposed to the environment, without causing infection.
What is infection?
Is the prescence of microorganisms causing damage to body tissues.
Is the invasion of a host organisms bodily tissues by disease causing organisms.
What are some factors that may cause/impact infection?
- Age, gender, ethnicity, nutrition, hygein
- Other conditions
- Drugs
- Immunocompromise
- Presence of foreign objects
- Public health factors
- Vaccination history
What is the importance of pre-antibiotic sampling?
Results allow pathogens to be identified, and problem is identified, allowing therapy to be tailored.
What is sepsis?
Physiological response to severe infection involving cytokine cascades, free radical production and vasoactive mediators.
What system is used to score sepsis?
sofa score system
When would you say someone has SIRS (systemic inflammatory response)?
When 2 physiological parameters are breached
When would someone have sepsis, severe sepsis and septic shock?
- Sepsis; SIRS in prescence of infection
- Severe sepsis; when you have organ hyperfusion caused by sepsis
- Septic shock; severe sepsis with hypertension
What are exotoxins?
An exotoxin is a toxin secreted by bacteria. They can cause damage to the host by destroying cells or disrupting normal cellular metabolism. Exotoxins may be secreted, or, similar to endotoxins, may be released during lysis of the cell
What are endotoxins?
Endotoxins are heat stable lipopolysaccharide-protein complexes which form structural components of cell wall of Gram Negative Bacteria and liberated only on cell lysis or death of bacteria. They elicit a strong immune response in man (e.g., fever, septic shock), and cannot be removed from materials by normal sterilization processes
What are the principles of treatment of infection?
- Investigate (imaging, cultures to guide later management)
- Conservative (rehydration)
- Antibiotics
- Surgical
- Infection control
- Public health
What are some universal infection control precautions?
- care with body fluids
- handwashing
- ppe
- cleaning
- injury prevention
What are some transmission based infection control precautions?
- may involve some sort of isolation (special PPE)
- airborne precautions
- contact precautions
- droplet precautions
What are the stages of the chain of infection?
- Portal of entry
- Susceptible host
- Infectious agent
- Resevoirs
- Portal of exit
- Means of transmission
What are some common examples of gram positive caucus?
Staph. Aureus
Strep. pneumonie
What are some common gram positive recilae?
Listeria monocytogenes
Cornebacterium diphtheriae
What are some common gram negative caucus?
Neissera meningitis
What are some common gram negative recilae?
Escherichi coli
Salmonella species
