Infection Session 1 Flashcards
Why do antifungals have a high level of toxicity?
Fungi are eukaryotic cells (so are human cells) so it has hard to target fungus and not host cells
How are some individuals naturally immune to viruses?
Lack receptors for specific proteins/glycoproteins present on viral surface
What must the nucleic acid of a virus be supplemented by to form virions.
Host cell genes
Is the protein coat of all viruses similar?
No, varying degrees of complexity
What does the Baltimore classification system use to categorise viruses?
Nucleic acid structure and method of replication
Mycoplasma, Chlamydiae, Rickettsiae are all obligate intracellular parasites. What does this mean?
Need a cellular host to survive
Give an example of a ssDNA non-enveloped virus.
Parvovirus 19
Give an example of a dsDNA non-enveloped virus.
Adenovirus
HPV
Give an example of a dsDNA enveloped virus.
Herpes virus
Hepatitis B
Give an example of ssRNA +ve strand non-enveloped virus.
Coxsackie virus
Norovirus
Hep A&E
Give an example of ssRNA +ve strand enveloped virus.
HIV
Hep C
Give an example of a disease caused by a ssRNA -ve strand enveloped virus.
Ebola
Lassa Fever
Measles
Give and example of a dsRNA non-enveloped virus.
Rotavirus
What are bacteriophages?
Viruses that transmit DNA to a bacteria
How do bacteriophages cause disease?
Transmitted DNA codes for the production of toxins
How can bacteriophages contribute to antibiotic resistance?
Transmit DNA which contains resistance genes
Which part of the bacterial structure forms the basis for immunisations?
Polysaccharide capsule
What can bacteria release to aid pathogenesis?
Enzymes to increase invasiveness
Chemicals to gain nutrition from surrounding e.g. Iron
Which virulence factor do pili affect?
Adherence to host cells
How can obligate anaerobes survive in oxygen?
Form spores which coat the bacteria and protect it from oxygen
Why can’t the same conditions used to kill vegetative bacteria be used for sterilisation?
Need much higher temperature and pressure to destroy spores
What system is used to name bacteria, fungi and parasites?
Linnaean
Give two examples of G+ve cocci.
Staph aureus Coagulase -ve staphylococcus Alpha- and beta-haemolytic streptococci Strep pyogenes/pneumoniae Enterococcus faecalis
Give two examples of G-ve cocci.
Neisseria meningitidis/gonorrhoea
Moraxella catarrhalis
Acinetobacter baumannii
Give two examples of G+ve bacilli.
Listeria monocytogenes
Bacillus anthracis/cereus
Give two examples of G-ve bacilli.
E. coli
Salmonella typhi
Klebsiella pneumoniae
Haemophilus influenzae
What is the causative agent in thrush?
Candida albicans
Which organism causes an AIDS defining meningitis?
Cryptococcus neoformans
What type of mould are ringworm and athlete’s foot?
Dermatophytes
What are single-celled parasites called?
Protozoa
Give two examples of protozoa.
Giardia lamblia
Cryptosporidium parvum
Plasmodium falciparum
What category of pathogen do roundworms, tapeworms and flukes belong to?
Helminths
Give an example of a fluke which can cause malignancy.
Schistosoma mansoni
What S/S are associated with tapeworm infection?
None - usually asymptomatic but can cause neurological disease
What is the difference between yeasts and mould?
Yeasts are single celled fungi
Moulds are multicellular fungi
What is an infection?
Invasion of a host’s tissues by microorganisms and disease
What are microbiota?
Microorganisms carried on skin and mucosal surfaces which are normally harmless or even beneficial
What are the three methods of horizontal transmission?
Contact
Inhalation
Ingestion
Why dint droplets spread as far as aerosols?
They are heavier
What are the stages that allow microorganisms to cause disease?
Exposure –> adherence –> invasion –> multiplication –> dissemination
Why is targeting the host immune response in treatment of infection potentially more effective than killing the pathogen itself?
Host immune response is usually more destructive
What are exotoxins?
Molecules released by a pathogen which can damage the surroundings to promote survival of the pathogen
What are endotoxins?
Parts of the bacterial cell wall which are released when the bacteria dies
What is the difference in supportive and specific investigations when identifying an infection?
Supportive identify to what extent a pt is unwell
Specific identify the causative agent
What supportive investigations can be performed in suspected infection?
FBC CRP LFTs U&Es Imaging Histopathology
What is MC&S in specific investigations of infection?
Microscopy, Culture and antibiotic Susceptibility
Which specific investigations in infection can utilise dead pathogens e.g. in heart valve removal?
Antigen and nucleic acid detection
What virology specific investigations can be performed in a suspected infection?
Antigen detection
Antibody detection
Detection of viral nucleic acid
