Microbiology Flashcards
Define an outbreak (2)
greater-than-normal or greater-than-expected number of individuals infected or diagnosed with a particular infection in a given period of time, or a particular place, or both.
Give 3 reasons/aims for investigating an outbreak. (3)
- Identify source of outbreak
- develop strategies to prevent future outbreaks
- evaluate existing prevention strategies
- describe new diseases + learn more about known diseases
- address public concern
What are the 5 steps for investigating an outbreak. (5)
- Preliminary Investigation
- Case definition and identification
- Descriptive study
- Analytic study
- Control-
Some patient has a chest infection. List 3 ways to collect a sample from them. (3 mark)
- Broncho-Alveolar Lavage (BAL)
- Nasopharyngeal Aspirate (NPA)
- Throat Swab
- ET secretions
List four bacteria that can be cultured from a chest infection (4)
- myco. tuberculosis
- streptococcus pneumoniae
- haemophilus influenzae
- Legionella pneumophila
Explain why looking at sputum and doing a tissue stain is useful (3 marks)
Sputum would have pathogen trapped in it
Determines if gram negative or positive: so identifies appropriate treatment
What causes hospital acquired infections?
- High density of sick patients - easy to spread
- Health care health care professionals going between patients
- Invasive procedures and catheterisation ect
Name 3 hospital acquired microbes
- Enterobacter faecium
- Staphylococcus aureus
- Clostridium difficile
- Acinetobacter baumannii
- Psudomonas aeruginosa
- Enterobacter and E.coli
- (ESCAPE)
Name 4 community pathogens that might enter the hospital
- s.aureus
- c. difficile
- baumanii
- p. aeruginosa
What is meant by nosocomial infection and when can it be diagnosed? (2)
An infection acquired in hospital after 48hrs
• diagnosed 48hrs after admission
Name 4 important bacterial causes of nosocomial infection and state whether they are gram positive or negative. (4+4)
- Enterococcus faecium (+)
- Staphyloccocus aeureus (+)
- C. Difficile (+)
- Acinetobacter baumannii (-)
- Pseudamonas aeruginosa (-)
- E. coli (-)
- (ESCAPE)
Name 2 examples each of Flagellae and Coccidiae and the diseases they cause in this table (8 marks)
Coccidiae:
• plasmodium (causes malaria)
• toxoplasma gondii (causes toxoplasmosis)
• crypotosporidium (diarrhoea)
Flagellae:
• Giardia lamblia (giardiasis)
• Tryponosoma (trypanosomiasis via Tsetse fly)
• Trichomonas (vaginal discharge, vaginitis)
• Leishmania (Leishmaniasis via sand fly)
State 2 helminth infections (2 marks)
- Hookworm
- Filariasis (Filaria)
- Ascariasis
- Strongyloidiasis
Give an example of a gram positive infection, say what antibiotic it is resistant to and say how the antibiotic works
Staphylococcus Aureus - Methicillin - inhibits transpeptidase which is needed for bacterial cell wall synthesis
NOTE : think MRSA - methicillin resistant s aureus
E. faecium - Vancomycin - inhibits peptidoglycan synthesis by binding to peptidoglycan precursor
Give 3 examples of bacterial pathogens that can be vaccinated for
Hemophilus influenzae Neisseria meningitidis clostridium tetani corynebacterium diphtheriaea Salmonella typhi Bacillus anthracis Bordetella pertussis
Give 2 examples of bacteria causing respiratory tract infections
Strep. pneumoniae, Mycobacterium tuberculosis, Legionella pneumophila
Give three characteristics of the bacterium causing the 2011 E. coli outbreak
Enteroaggregative Produces shiga toxin Had 2 plasmids, so horizontal gene transfer was possible? AAF is its virulence factor 8 day incubation period
List three symptoms of haemolytic uremic syndrome
Acute renal failure
Haemolytic anemia
Thrombocytopenia
4 types of protozoa and examples of each (4)
Amobae - Entamoeba histolytica
Coccidia - plasmodium
Ciliate - balantidium coli
Flagellate - Giardia lamblia, leishmania
What is the difference between protozoa and metazoan? (1)
protozoa = single celled, metazoa = multicellular
What are the two types of leishmaniasis and give features of each (4)
Visceral - affects internal organs e.g. hepatomegaly, splenomegaly, often fatal if untreated, treat with sodium stibogluconate.
Cutaneous - skin lesions, further subdivided into 3 types but basically less serious, may cause scarring or destroyed mouth & nose in severe cases
What cell type do leishmania reside in? (1)
Macrophage
What are endotoxins and exotoxins?
Exotoxins - toxins produced by bacteria and released extracellularly.
Endotoxins - lipid A of lipopolysaccharide from Gram – bacteria
What are Pyrogenic toxins?
Exotoxins that stimulate the release of inflammatory cytokines - cause fever
2 virulence factors other than toxins that are used by bacteria
Secretion systems, flagellae, pili, endospores, Biofilms, capsule
What are genetic drift and genetic shift?
Genetic drift - Continued rapid evolution driven by antigenic pressure from host
Genetic shift - Introduction of new subtypes from animal source
How do viruses evade interferon detection?
Evasion:
Virus not processed at proteasome - EBV
Block TAP peptide - HSV
Prevent TAP peptide from translocating - CMV
Prevent loading into MHC - CMV
polyubiquitinylation and internalization of MHC - KSHV
Viruses encode MHC analogues or upregulate MHC production – CMV
Give two examples of cytoplasmic sensors for viruses
cGAS senses viral DNA in cell - binds to DNA - forms cGAMP - binds to STING on endoplasmic reticulum -> transcription factor phosphorylation and movement to nucleus e.g. IRF 3 -> interferon transcription
RIG also intracellular detector - results in transcription factor phosphorylation and movement to nucleus
Name two bacterial pathogens that use pyrotoxins. [2]
streptococcus pyogenes staphyloccoccus aureus
Name the general term for the type of toxin that binds directly to both MHCII and T cell receptors
superantigens
Name two virulence factors and for each one, name a bacterial pathogen that uses them
neurotoxins - botulinum enterotoxins - vibro cholerae Pili Secretion systems 3 (samonella) and 4 (legionaires) capsule
Example of Coccidiae that is important to humans, what condition does it cause and give two clinical features (4 marks)
- plasmodium malaria clinical features: headaches, muscle pain
- toxicoplasma gondii toxoplasmosis clinical features: CNS disease, pneumonitis
What are the two types of leishmaniasis and give features of each (4 marks)
Visceral weight loss, liver swelling, anaemia, splenomegaly
- Cutaneous skin lesions, scaring
What is the parasite vector for leishmaniasis and describe how? (2 marks)
- sandfly
- sandfly ingests leishmania inoculates human infects human when it bites it
