Module 4 Flashcards
infection
when microorganisms invade host tissue and multiply
subclinical infection
no symptoms but immune response had happened
localised infection
confined to one area of body
systemic infcetion
spreads to other organ systems
pathogen
microorganism capable of causing disease
pathogenesis
process in which disease arises
pathogenicity
measure of ability of pathogen to cause disease
pathogenic determinant
feature that influences how well it can cause disease
endemic
disease always present in population
epidemic
sudden rapid rise in disease incidence
pandemic
global epidemic
outbreak
high number of infections where no cases occured in the past
Define Koch’s postulates
- suspected pathogen must be present in all cases of disease and absent from healthy animal
- pathogen must be grown in pure culture
- cells from pure culture must cause disease in healthy animal
- pathogen must be deisolated and shown to be the same as the original
What are the progression stages of an infectious disease
incubation period, prodromal phase (minimal symptoms), invasive phase, acme (highest point), decline phase and convalescence period
Differences between gram positive and gram negative
Positive have thick layer of peptidoglycan cell wall and negative have thin layer
Stages of bacterial reproduction
lag phase, exponential/ log, stationary and death
enveloped virus
entire virus is surrounded by outer membrane derived from host cells
6 viral lifestyle steps?
- attachment
- penetration
- uncoating
- replication
- assembly
Tropism + 3 types
virus target specific cells
cellular, tissue and host
where do RNA Viruses replicate
cytoplasm
where do DNA viruses replicate
nucleus
Describe the infection consequences of viral infection
- acute infection - infection cleares
- productive chronic infection - persistent infection for a long time
- non-productive latent infection - virus remains present but not active, may appear later
- transformation - transforms host cell into tumour or cancer
pathophysiology
damage to cells due to virus replication and host response
2 DNA viruses
DNA - Pappilomavirus and Herpesvirus
2 RNA viruses
RNA - Coronavirus/ Influenza and Flavivirus
3 major fungi groups
macroscopic - mushrooms
multicellular filamentous moulds
singe cell yeasts
3 pathogenic fungi types
filamentous, yeast, dimorphic
basic fungal structure and function
thick carbohydrate wall
- protects from environment
- acquisition of nutrients
- cell recognition and mating
3 fungi structure types
moulds, yeast and dimorphic
3 types of fungal infections
superficial mycoses - ringworm and thrush
subcutaneous mycoses - madura foot
systemic mycoses - histoplasmosis
3 parasite types and examples
helminths - pinworm
protozoa - Plasmodium causing malaria
arthropod - ticks and fleas
Describe how healthcare environment contributes to incidence of infectious disease (3)
- older and vulnerable hosts
- multiple routes of infection
- use of antimicrobials - constant pressure is selective for resistant organisms
Describe what is meant by MRSA, its key virulence factors and pathophysiology
methicillin- resistant staphlyococcus aureus
resistant to many first line antibiotics and beta-lactam antibiotics.
Bacterial HCAI’s
C. Diff - found in feces of babies and in disturbed gut bacteria in adults
UTI’s - mostly caused by e.coli and can lead to kidney infection
Viral HCAI’s
RSV- lower respiratory infection in babies and is transmitted via objects
Rotavirus-neonatal diarrhoea and its transmitted faecal- oral
Antibiotic targets (4)
- cell metabolism
- cell wall synthesis
- nucleic acid synthesis
- cell membrane function
Describe bacterial antibiotic resistance mechanisms
- production of enzymes- destroys the antibiotics
- alteration of bacterial binding sites- antibiotics cant get in cause binding site has changed
- change in membrane permeability - outer membrane protein block
- alternate pathways - drug efflux pumps and targeting overproduction
Describe what human practices can lead to antibiotic resistance and what can be done to prevent it
- low dosage
- poor adherence
- poor prescribing - viral infection
- use of broad- spectrum antibiotics
Routes of infection
- airborne
- direct or indirect contact
- faecal oral
- vector borne
- sexual
sterilisation + eg
killing of all viable organisms
eg. Heat or irridation
disinfection + eg
killing of most viable organisms
eg. chemical disinfectant or filtration
infection controls management
hand hygeine
ppe
contact precautions
cough etiquete
what makes host susceptible
age, immunocompromised, pregnant, trauma
Consequences of hospital infections
illness or death
prolonged stay in hospital
patient becomes source of infection
prevention of hospital infections
exclude sources of infection from environment
interrupt transmission from source to host
increase host resistance
patient management of infection
minimise operation length
adequate wound drainage
preventing sores
shape of ‘staphe’ bacteria
grapes
shape of ‘coccus’ bacteria
round berry
aurus
gold
shape of ‘bacci’ bactera
ros shaped
classification of a virus
type of nucleic acid
arrangement of nucleic acid
structure of virus particle
symmetry of capsid
pathogenic consequences of viral infection
acute infection
productive chronic
non productive latent
transformation
types of antimicrobials
anti parasitic
anti fungal
anti viral
anti bacterial - antibiotics
gene transfer
transformation
transduction
conjugation
transponsons
