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95 Cards in this Set
- Front
- Back
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What does staph saprophyticus cause? |
UTIs |
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Staph epidermidis infects |
The skin |
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What type of bacteria is Staphylococcus |
Gram positive cocci |
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How many capsular serotypes of staph are there? |
11 |
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Capsule and polysaccharide slime layer prevent ..... As well as helping |
Phagocytosis , bind to tissues or fomites |
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What is a fomite? |
Any inanimate object that when contaminated or exposed to infections agents can transfer disease to new host |
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Peptidoglycan layer of staph has |
Endotoxin like activity, stimulates the immune system |
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Protein A in staph binds |
To igG |
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Virulence factors enable microbial pathogens to .... (5) |
Colonization of a niche in the host Immuno evasion Immuno suppression Entry and exit out of cells Obtain nutrition from host |
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Toxic shock syndrome is caused by what bacterias? |
Staphylococcus or streptococcus |
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What is toxic shock syndrome toxin 1 |
Is a superantigen that stimulates a massive release of cytokines Responsible for the majority of menstruation associated toxic shock syndrome cases |
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At low concentrations TSST-1 does what? |
Producing leakage of endothelial cells at low concentrations |
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What are endothelial cells? |
Cells that line blood vessels |
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What does TSST-1 cause at high conc |
Cytotoxic effects |
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Under magnesium limited conditions when tampons are in use ..... Grows fast increasing .... Production |
S. Aureus Tsst-1 |
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Why do tampons increase risk of TSS |
Tampons that are left in the vagina for a long time may encourage bacteria to grow Tampons can stick to the vaginal walls, causing tiny abrasions when they are removed |
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3 toxins that S. aureus produce ? |
Toxic shock syndrome toxin 1 Bicomponent toxin - PVL Exfoliative toxin - ETA or ETB |
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Which is more common ETA or ETB? |
ETB is more common |
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What do exfoliative toxin cause? |
Staph scaled skin syndrome |
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How many beta-barrel pore forming toxins is S.aureus known to produce? And how are they all different? |
8, they target different cell surface receptors |
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6 staph enzymes |
Catalase Hyaluronidase Fibrinolysin Lipases B-lactamase Nuclease |
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What does nuclease do? |
Degrades NETs |
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What does B-lactamase do? |
Penicillin resistance |
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What protects S.aureus from phagocytosis and inhibits complement activation? |
Protein A Sbi - staphylococcal ig binding protein |
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Protein A functions as a b cell superantigen binding to the .... Of ...... And cross-linking specific B cell receptors |
Fab domain IgM |
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SplB degrades |
Complement components C3b |
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Nosocomial infection |
Health care associated or hospital acquired infection |
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3 types of staph diseases |
Scalded skin syndrome Toxic shock Food poisoning |
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What is a suppurative infection |
One in which pus is formed and discharged |
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Suppurative infections caused by staph (5 examples) |
Impetigo Furuncles Bacteraemia Pneumonia Osteomyelitis |
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How can s.aureus be diagnosed? (3) |
Bacterial isolation rate Culture differentiation Determinative tests |
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what agars can be used for culture differentiation of S.aureus ? |
Blood agar Mannitol salt agar Baird -parker agar |
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How does blood agar differentiate between staph species? |
S.aureus = golden yellow colonies White colonies = coagulase negative staph (such as s.epidermis |
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What does blood agar tell us about pathogenicity? |
Anything that can be a human pathogen will grow on blood agar |
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How can mannitol salt agar be used for s.aureus ID? |
High salt favours the growth of more salt tolerant strains of staph Mannitol and pH indicator which allows distinction between organisms which can ferment mannitol |
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What colour does s.aureus show on mannitol salt agar? |
Yellow |
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What is blood agar ? |
General purpose agar used to differentiate bacteria based on their haemolytic properties |
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Coagulase test for s.aureus ? |
Positive |
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Catalase test for s.aureus ? |
Positive |
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What do s.aureus colonies look like on Baird-parker agar? |
Black with a zone of clearing |
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What does baird-parker agar contain? |
Tellurite and lithium chloride |
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What determinative tests can be used for s.aureus ? (4) |
Catalase Coagulase Baird parker agar Staphaurex test |
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How would you treat s.aureus infection and why? |
Vancomycin can be used as a first port of call Most s.aureus species are resistant to all penicillins (MRSA) now |
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How do you get a staph infection? |
Normal flora on human skin When staph get further into the body it can cause infection |
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Risk factors for staph infection? |
Foreign body Surgical procedure Antibiotic use |
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Who is more at risk of getting a staph infection? |
Infants Menstruating women Catheters Shunts |
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What is an arbovirus? |
Any virus that can be transmitted via blood-feeding arthropods and arachnids |
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What families of viruses are within the arboviruses group? |
Togaviridae Flaviviridae Bunyaviridae |
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To be a arbovirus the virus must be able to? (3) |
- Infect both invertebrates and vertebrates - Initiate viremia in a vertebrate host - Intiate a persistent, productive infection of the invertebrates salivary glands |
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What is usually the reservoir for arboviruses ? |
Birds and mammals |
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Humans are usually ..... For arboviruses |
Dead end host |
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Urban outbreaks of arboviruses usually occur ... |
When the reservoir is human or urban animals |
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What viruses are in the family togavirus? |
Alphavirus Rubrivirus |
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What viruses are in alphavirus ? |
Eastern equine encephalitis Venezuelan equine encephalitis Western equine encephalitis |
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Genome of alpha virus |
+ve sense RNA , unsegmented |
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Structure of alpha virus |
Icosahedral 80 glycoproteins spikes on the surface |
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Alpha virus replication |
- Receptor mediated endocytosis - RNA genome is released - First 2/3 of genome translated into a single polyprotein - polyprotein cleaved unit 4 NSP -Other 1/3 translated into polyprotein then cleaved into capsid proteins and envelope glycoproteins |
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How are alpha viruses released from host cell |
Budding |
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How many envelope glycoproteins do alphaviruses have |
3 |
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Each nonstructural protein of alpha virus contains |
A protease and RNA dependant polymerase |
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Flaviviridae genome is |
Ss +ve RNA viruses |
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Three viruses from the flaviviridae? |
Flavivirus Pestivirus Hepacivirus |
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Name some flaviviruses? |
Zika virus , West Nile virus , dengue virus, yellow fever |
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How is flavivirus translated? |
As a single polyprotein |
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How do flaviviruses enter a host cell? |
Receptor mediated endocytosis |
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How many nonstructural proteins does flavivirus genome encode? |
7 |
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How many structural proteins does flavivirus genome encode ? |
3 |
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How is flavivirus envelope acquired |
Capsid budding into intracellular vesicles |
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Arbovirus causes cell death through 3 mechanisms? |
- Viral mRNA blocks cellular mRNA ribosome binding - Increased membrane permeability - Degradation of dNTPs |
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Dengue and yellow fever viruses are known as |
Haemorrhagic viruses |
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What viruses are in the family bunyaviridae? |
Bunyaviris Phlebovirus Nariovirus Ukuvirus |
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How many glycoproteins do buyaviruses have |
2 |
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Bunyavirus genome |
Three segments Ss - RNA |
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Why are viruses with segmented genomes more dangerous |
Because they can easily reshuffle their genes with another virus infecting the same host cell |
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How do buyaviruses enter the cell |
Receptor mediated endocytosis |
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How does bunyavirus exit the host cell |
Cell lysis |
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What genome segment of bunyavirus transcribes the others and why? |
L segment as it is the RNA polymerase |
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Name three trypanosomatid parasites that are medically important |
Trypanosoma Brucei Cruzi Leishmania species |
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What does t.brucei cause |
Sleeping sickness |
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What does t.cruzi cause? |
Chagas disease |
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How is t.cruzi transmitted? |
Bite and defecation if the triatomine bug (kissing bug) |
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What is another name for Chagas disease? |
American trypanosomiasis |
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What parts of the body does Chagas disease affect? |
Heart, gastroentestinal tract and CNS |
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How do you treat Chagas disease |
Nifurtimox and bensnidazole |
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What is leishmania ? |
Flagellated protozoan parasite that can cause cutaneous, mucocutaneous and visceral leishmaniasis |
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What is leishmania transmitted by |
Sand fly |
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Leishmania Mexicana causes |
Cutaneous leishmaniasis |
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How to treat cutaneous leishmania |
Amphotericin B and miltefosine |
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Leishmania infects what type of cells |
Macrophages |
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Leishmania braziliensis causes |
Mucocutaneous leishmaniasis |
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How to treat mucocutaneous or visceral leishmaniasis |
Amphotericin B Miltefosine |
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Leishmania donovani causes |
Visceral leishmaniasis |
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What typanosomatid species are intracellular parasite's? |
Leishmania and t.cruzi |
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Which trypanosomite species is an extracellular parasite? |
T.brucei |
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What is an amastigote? |
Parasites forms that persist in the infected host |
