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Flashcards in Scenario 15 Deck (102)
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31

How do you treat e coli?

Amoxicillin

32

How do you distinguish pseudomonas aerginosa

Gram negative non sporing bacillus, non lactose fermenting, outer membrane with LPS, porins and proteins, large genome

33

What are the virulence factors of pseudomonas aerginosa

Endotoxins, exotoxins, iron binding proteins

34

Where is it found and how is it transmitted?

Soil and water, colonises UT, transmitted on medical equipment, water, spas and whirlpools

35

How do you treat p. aeruginosa?

Resistant to co-amoxiclav, trimethoprim, nitrofurantoin use piperacillin-tazobactam and gentamycin

36

How do you distinguish Haemophilus influenzae?

Gram negative rod (sometimes coccobacillus) needs media with growth factors and cell membrane with LPS, proteins and porins

37

What virulence factors are present in haemophilus influenza?

Endotoxin, large polysaccharide capsule, IgAse, adhesins in cell wall

38

Where is h.influenzae found?

Mucosal surfaces transmitted with close contact and droplets

39

What infections does it cause?

Bloodstream infection in young children (capsulate) and ottis media, sinusitis, conjunctivitis all ages (not capsulate)

40

How do we treat H.i?

Vaccine in childhood, amoxicillin (15% resistance) chemoprophylaxis, IV ceftriaxone for invasive infections

41

What other gram negative bacteria are there?

Bacteroides (rod- colonise the mouth), neisseria (cocci in pairs, mucous membranes, inside neutrophils- meningococcus, gonococcus), legionella (rod, pneumonia), heliobacter pylori (rod, stomach)

42

What is the basic structure of a virus?

DNA or RNA core with protein coat, some have an envelope studded with glycoproteins

43

Where do non-enveloped viruses survive best?

Outside of cells and bile resistant

44

Where do enveloped viruses survive best?

In cells- only spread by close contact eg. Hep B HIV

45

Which viruses are RNA?

Retrovirus, coronvirus, picornavirus

46

Which viruses are DNA?

Adenovirus, herpesvirus, poxvirus

47

What are the steps in viral replication?

Attachment, penetration, uncoating, transcription, translation, replication, assembly, release

48

How do DNA viruses replicate?

Large replicate on their own, small encode only a few genes and use host cell DNA polymerase etc

49

How do RNA viruses replicate?

Most RNA viruses encode their own RNA-dependent RNA polymerase using complementary RNA as template
-Positive strand RNA- equivalent to mRNA can often be immediately translated into proteins then synthesise a -ve copy copied back into -ve mRNA messages to produce structural proteins to package progeny +ve RNA into visions
-Negative strand RNA- first converted into +ve RNA (.RNA) by RNA dependent RNA polmerase then same as abover

50

Why do RNA viruses replicate more quickly?

RDRP lacks proofreading ability and makes more mistakes

51

How do retroviruses replicate?

encode reverse transcriptase which makes dsDNA from RNA

52

What is a latent infection?

Viral DNA persists but doesnt replicate to produce new infectious virus e.g. herpes, varicella zoster

53

What is pathogenesis?

Process where infecion leads to disease

54

What are the virus properties that allow it to inhabit cells?

Concealment (prevent antigen presentation, latency, integration into genome- retrovirus), intefere with cytokine network (mimic receptors and inhibitory cytokines and interfeon), antigenic variation (mutation and antigenic shift), modulation of lymphocyte function (immuno suppression)

55

What is the eclipse phase?

Virus entry until new infectious virions released

56

What is the classification of family herpesviridae?

Large dsDNA icosahedral capsid and lipid envelope

57

What subfamiliy does varicella zoster belong to?

Alphaherpesviridae

58

Where is chicken pox latent?

Dorsal root or cranial nerve ganglion- reactivation= chicken pox

59

What is the incubation period for varicella?

10-21 days- prodrome (fever, pharyngitis, malaise)

60

What are the complications of varicella?

Sever haemorrhagic, pneumonia, acute cerebellar ataxia, encephalitis