Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Z MD1 Practical > micro sem 1 > Flashcards

micro sem 1 Flashcards

1
Q

definition of bacteraemia

A

the presence of bacteria in the blood (needs not to be associated with clinical features or any symptoms)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

definition of septicaemia

A

serious systemic infection associated with bacteria or their products in the blood, resulting in a systemic response and changes in organ perfusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

definition of sepsis

A

associated with infection resulting in fever or hypothermia, tachycardia and/or tachypnoea, and high/low WBC count

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

definition of septic shock

A

severe sepsis combined with a potentially fatal drop in blood pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

typical sources of micro-organisms causing septicaemia

A

skin URT genito-urinary tract GI/biliary tract

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

common gram positive bacteria that cause septicaemia

A

staph aureus (golden staph), streptococcus pyrogenes, staph epidermidis, viridans streptococci, strep pneumoniae, enterococcus spp.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

common gram negative bacteria that cause septicaemia

A

e coli, pseudomonas aeruginosa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

basis of catalase test

A

if micro-organism has enzyme - able to break down H2O2 to water and oxygen Only aerobic and facultative aerobes have catalase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

why is the catalase test important

A

if you have found a gram positive bacteria = either staph or strep staph is catalase +ve, while strep is catalase -ve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

basis of coagulase test

A

a test for the ability of staph sp. to clot plasma by the action of coagulase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

why is the coagulase test important

A

if staph is found –> do coagulase test –> if positive = staph aureus (makes a fibriogen shield around itself - difficult for IS)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

why is the lactose test important

A

important to know whether or not a gram -ve bacilli is a lactose fermentor or not

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is main reason for doing DIRECT antibiotic susceptibility testing

A

to try and save time (done straight from the blood culture)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is staph aureus resistant to

A

penicillin - always

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

why is cefoxitin susceptibility testing done

A

as a surrogate for methicillin susceptibility testing - cefoxitin a lot easier to use than methicillin - they act in the same way

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

if a wound smells bad…

A

it is probably an anaerobic bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

clostridium is always

A
  • environmental - normal microbiota of the gut - gram +ve rod - strict anaerobe form spores
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

why is strep pyrogenes so pathogenic?

A
  • has enzymes that allow it to spread through the tissues - has superantigens –> causes systemic effects - is capsulated by hyaluronic acid - self protein
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

treatment of strep pyrogenes

A

ALWAYS SUSCEPTIBLE FOR PENICILLIN

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

sweet smelling ooze from a wound….

A

probably pseudomonas aeroginosa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

a patient may be suspected of having a primary immunodeficiency if they have (10)

A
  • 8 or more ear infections within one year - 2 or more serious sinus infections within one year - 2 or more months on antibiotics with little effect - 2 or more pneumonias within one year - failure of an infant to gain weight/grow normally - recurren
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

recurrent infections by pyogenic bacteria (E/C bacteria) typically associated with defects in which parts of the immune system?

A
  • antibody production - components of the complement cascade - phagocyte function
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

recurrent infection by viruses, I/C bacteria and fungi are typically associated with defects in which part of the immune system? What may this impact on?

A

T cell function may impact on: - function of CD8 cytotoxic T cells - function of CD4 T cells - B cell and macrophage function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what micro-organisms is a person susceptible if they have hyper IgM syndrome

A

both extracellular and intracellular pthogens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what is the most common reason for Hyper IgM syndrome?

A

mutation in the gene encoding the CD40 ligand that is induced on activated T cells- required for isotype switching, activating macrophages and generating cytotoxic T cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What does IL-12 receptor deficiency cause

A

affects the ability of T cells to bind IL-12 and differentiate into TH1 cells resulting in defective IFN gamma production

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what does an IL-12 receptor deficiency make you susceptible to?

A

excessof infections with I/C bacteria, such as TB - since macrophages cannot be appropriately activated in the absence of T cell derived IFN gamma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

deficiencies of antibody production usually results in

A

difficulties in clearing EC bacteria and usually manifest themselves as recurrent pyogenic infections

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What does a mutation in the btk gene cause?

A

pre-B cells cannot differentiate into mature B cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Which parts of the innate immune system can be defective?

A
  • the complement system defect - phagocytic cell defect - cytokine defect
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

what does a deficiency in C3 cause

A

reduced ability to opsonise organisms for phagocytosis –> increased susceptibility to pyogenic infections

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Having a faulty MAC makes you susceptible to infection by which species and why

A

neisseria genus - able to evade the normal phagocytic defenses so the formation of the MAC is critical for their control

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What does a LFA-1 deficiency lead to?

A

the inability of the phagocytes to bind to vascular endothelium and a failure to bind bacteria coated with C3b –> patients phagocytes fail to migrate to sites of infection, or ingest opsonised organisms –> overwhelming bacterial infections

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

what is chronic granulomatous disease?

A

a disease in which phaogcytes ingest but fail to kill ingested organisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

what causes chronic granulomatous disease?

A

patients phagocytes are defective in NADPH oxidase –> cannot produce superoxide radicals (important for bactericidal pathway)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What is IFN-gamma important for?

A

activation of macrophages to ingest and kill EC pathogens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

what produces IFN-gamma?

A

TH1 CD4 cells CD8 T cells NK cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

what do you look for in the blood to determine which component of the immune system is defective?

A
  • presence of expected cell populations by flow cytometry - presence of expected levels of complement components - presence of expected antibody isotypes - functional assays - assays for gene defects
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

if a phagocyte can engulf but not kill, what results?

A

the formation of giant cell granulomas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

what microorganism normally causes the formation of giant cell granulomas? Why?

A

mycobacterium - inhibits the killing pathways of activated macrophages, and survive and multiply inside the infected macrophage –> chronic persistent infection –> stimulates and is controlled by the development of a granuloma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

defects in the gene coding for CD40L leads to which typical problems:

A
  • poor B cell activation (poor isotype switching, affinity maturation and memory cell formation) - inefficient induction of cytotoxic T cells - inefficient macrophage activation, resulting in defective cytokine release, and defective respiratory burst
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

what is granuloma development dependent on? (cytokine)

A

the products of activated T cells - especially IFN-gamma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Normal proliferation of T cells is induced by?

A

IL-2

44
Q

deficiency of LFA-1 leads to…

A

phagocytes unable to migrate into the tissue

45
Q

a defect in the gene coding for gene rearrangement (RAGs) would lead to..

A

no T or B cells

46
Q

how do you take blood cultures

A

take 3 sets of 2 bottles one bottle of the set cultured anaerobically the other aerobically

47
Q

if a wound smells bad, it is probably…

A

an anaerobic organism associated with dead tissue

48
Q

catalase test is based on

A

whether or not a bacterium can break down H2O2 to water and oxygen

49
Q

coagulase test is based on the ability to

A

clot plasma by the action of the enzyme coagulase –> breaks down fibrin to fibrinogen

50
Q

when do you perform lactose fermentation tests

A

on gram -ve bacteria

51
Q

colour of gram positive and negative bacteria

A

positive - purple/blue negative - pink

52
Q

what is the purpose of macconkey agar

A

it is a selective mediator medium - has lactose as the nutrient: –> if bacteria ferments lactose = pink –> if bacteria doesnt ferment lactose = yellow identifies enteric bacterium

53
Q

purpose of oxidase test

A

mainly for the aerobic and facultatively anaerobic groups of gram negative bacteria (psuedomonas sp are positive)

54
Q

identification of staph aureus

A
  • gram +ve cocci - growth in air - catalase +ve - coagulase +ve
55
Q

identification of psuedomonas

A

gram -ve rods oxidase _ve grows aerobically

56
Q

what is the difference in blood pressure when moving your arm around

A

raised arm = lower BP higher arm = increased BP due to P= pgh

57
Q

difference between primary and secondary ID

A

primary = inherited, as a result of gene defects, developed in utero secondary = gained over life when something impacts the immune system

58
Q

when does primary ID usually present clinically

A

6-9 months

59
Q

what does the lack of CD18 cause

A

(part of integrin molecule on T cells) - T cells cannot get into tissues and therefore build up in the blood

60
Q

what is the classical organism causing consolidation in people with T cell defects

A

Pneumocystis jiroveci (fungi)

61
Q

lack of CD40L means what

A

no activation of B cells to help them isotype switch –> only IgM made against infections - action against viral infection is fine

62
Q

two types of antimicrobial treatment

A
  • empiric therapy - based on the most likely causative organism - directed therapy - based on the results of diagnosis and antimicrobial susceptibility testing
63
Q

which organisms is always susceptible to penicillin

A

strep pyogenes

64
Q

what am i? Small white colonies with beta haemolysis on HBA Gram positive in chains

A

Strep A, B or C

65
Q

what are the possible complications of a Strep pyogenes infection

A
  • rheumatic fever –> rheumatic heart disease - quinsey = peritonsillar abscess - sinusitis - mastoiditis - cellulitis - necrotising fascitis - speticaemia - septic arthris - endocarditis - glomerular nephritis
66
Q

different organisms that cause alpha and beta haemolysis on mcconkey agar

A

green haemolysis = strep pneumonia beta haemolysis= strep pyogenes

67
Q

what conditions may lower the resistance of the RT to bacterial infections

A
  • viral - smoking - blockage of bronchus - malnourised - COPD - patients undergoing surgery
68
Q

what does the presence of a capsid mean for fighting infection

A

complement cant bind to it antibodies cant bind to it evades alveolar macrophages

69
Q

what are the features of the secondary immune resonse that we want an ideal vaccine to geerate

A
  • isotype switching - affinity maturation - differentiation into memory cells (all require help from CD4 T cells)
70
Q

how do you activate T cells in a vaccine

A
  • CD40L - cytokines - peptide antigen
71
Q

T independent B cells can only make

A

IgM antibodies no memory response short lived response

72
Q

how would you look for, and what would you look for when trying to see infection with eukaryotic parasite

A
  • wet prep of faeces - light microscoy - look for parasitic form and cysts
73
Q

if you want to see if you can grow Campylobaccta, which medium do you have to use

A

Campylobacta agar - has blood and antibiotics it in - needs blood to grow - Ab restricts the growth of anything else

74
Q

which organisms are notifiable to the health department

A
  • Campylobacta - Shigella - Salmonella - EHEC - vibrio cholera - Cryptosporidium
75
Q

which enteric organisms are lactose non-fermenters

A

Shigella and Salmonella

76
Q

Which organism gives yellow colonies with a black dot in Disoxycholate citrate medium

A

Salmonella

77
Q

What does salinyte browth do

A

poisons normal microbiota, but now Salmonella –> red precipitate “Salmonella test”

78
Q

3 organisms that can cause bloody diarrhoea

A

EHEC Shigella dysenteriae EAEC that has acquired the Shiga toxin genes

79
Q

What is a CAMP medium used for?

A

test for Campylobacter

80
Q

What is a disoxycholate citrate plate used for

A

to test for the presence of Salmonella (will show up as yellow colonies with black dots)

81
Q

how does EHEC cause kidney damage

A

into blood stream –> kidney endothelial cell internalises it –> inhibits protein synthesis –> cell dies (cytotoxic) –> inflammatory response –> fibrin deposition

82
Q

what is the difference between complicated and uncomplicated cystitis

A

uncomplicated - no underlying medical condions that would predispose them to cystitis complicated - underlying medical conditions

83
Q

what is pain when peeing called

A

dysuria

84
Q

main causes of cystitis

A

E coli Staph saprophyticus proteus klebsiella enterococci pseudomonas

85
Q

which organism causing cystitis is associated with sexually active women of reproductive age

A

staph saprophyticus

86
Q

what is enterococci

A

gram +ve cocci that is catalase -ve (like strep)

87
Q

how many bacteria are significant in a urine sample

A

>10^5

88
Q

how many bacteria are significant in 1 microlitre

A

100

89
Q

what are the two essential tests on a dipstick that indicates cystitis

A

leucocyte esterase and nitrites

90
Q

macroscopic look of E coli

A

large round single colonies that are lactose fermenters

91
Q

macroscopic look of klebsiella

A

large round single colonies that are lactose fermenters that are shiny due to their polysaccharide capsule

92
Q

why is asymptomatic bacteruremia bad in pregnant women

A
  • predisposes to premature labour - babies tend to be low birth weight for gestation - get increased levels of kidney infection during pregnancy
93
Q

why do you treat urine with an alkali before culturing my M. TB

A

to get rid of the normal flora (as you have taken a full stream urine so there will be lots of bacteria present)

94
Q

identification of streptococci

A
  • gram positive cocci in chains - pyogenic - no spores - facultative anaerobe - often alpha or beta haemolysis on HBA - catalase negative
95
Q

staph identification

A
  • gram positive cocci in clusters - pyogenic - no spores - facultative anaerobes - catalase positive
96
Q

how would you test to see if you have staph aureus

A

catalase and coagulase positive

97
Q

how do you get staph

A

both exogenous (environmental) and endogenous

98
Q

identification of enterococci

A
  • gram positive cocci in pairs or chains - catalase negative - facultative anaerobe (like strep) - non haemolytic
99
Q

identification of pseudomonas

A
  • gram negative bacilli - aerobic, non-spore forming - oxidase positive
100
Q

likely sources of staph aureus

A

skin, nose, throat, faeces, HC workers

101
Q

likely source of strep pyogenes

A

nasopharynx, oropharynx

102
Q

likely source of pseudomonas aeroginosa

A

environmental

103
Q

what is serosanginous discharge

A

no pus in the discharge

104
Q

what is CD18

A

common component of integrin molecules needed for adhesion and movement of WBCs into tissues (eg. part of LFA-1)

105
Q

What is strep pyogenes normally associated with

A

cellulitis necrotising fascitis resp infections endocarditis systemic infections

106
Q

what physical symptoms are characteristic for acute bacterial meningitis

A

fever stiff neck headache

Z MD1 Practical (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions