Microbiology Flashcards
1
Q
What is virulence?
A
the capacity of a microbe to cause damage to the host
2
Q
What are virulence ffactors?
A
The factors responsible for the variation in virulence within and between species
3
Q
What is adhesin?
A
enables binding of the organism to host tissue
4
Q
What is invasin
A
enabled the organism to invade a host cell/tissue
5
Q
what is impedin?
A
enables the organims to avoid host defense mechanisms
6
Q
What is aggressin?
A
causes damage to the host directly
7
Q
What is modulin?
A
induces damage to the host indirectly
8
Q
Where is S.aureus found on the body?
A
anterior nares and perineum
9
Q
What skin diesases can Staph. aureus cause?
A
rash; folliculitis; carbuncle; impetigo; abscess; scalded skin syndrome
10
Q
What do adhesins bind to?
A
extracellular matrix molecules that are present on cell surfaces
11
Q
Give 2 examples of adhesins?
A
fibrinogen-binding
collagen-binding
12
Q
What disease does collagen-binding factor allow Staph. aureus to cause?
A
osteomyelitis
13
Q
Do all Staph. aureus have all virulence factors?
A
No
14
Q
What is the purpose of hte capsule?
A
a thick polysaccharide layer that allows bacteria to evade and hide from the immune system
15
Q
What is a toxinoses?
A
It is a disease that isn’t caused by the bacteria itself but by the toxin it produces
16
Q
What is a superantigen?
A
Doesn’t bind directly to MHC class 2 complex but binds outside conventional binding groove which causes a cytokine storm and inappropriate immune response
17
Q
Give an example of a superantigen
A
TSST-1
18
Q
What disease does TSST-1 cause?
A
Toxic Shock Syndrome
19
Q
What are the symptoms of Toxic Shock Syndrome?
A
fever
diffuse macular rash and desquamation
hypotension
more than three organs involved
20
Q
What does Panton- Valentine Leukocidin do?
A
specific toxicity for leukocytes so stop immune system working
21
Q
What conditions is PVL associated with?
A
recurrent furunculosis
sepsis/ necrotising fasciitis
necrotising pneumonia
22
Q
Why do antibiotics fail in the treatment of necrotising penumonia?
A
The toxin is causing the disease not the bacteria and the antibitocs do not target the toxin
23
Q
Describe Streptococci
A
gram positive cocci
chains
coagulase negative
24
Q
What skin infections does streptococcus pyogenes cause?
A
impetigo, cellulitis, necrotising fasciitis
25
If a microbe causes beta haemolysis, what does this mean the bacteria can do?
produce a protein that can destroy RBCs
26
What proteins are involved in helping Strep. pyogenes in adhesion?
M proteins
27
What superantigens cause Toxic shock like syndrome?
SpeB and SpeC
28
What allows both Staph. aureus and Strep. pyogenes to cause Toxic Shock?
Similar exo-proteins, common virulence factors and disease mechanisms
29
What is variation in disease and virulence the result of?
variation in genes
30
How do staphylococcus sp. appear on staining
gram positive cocci in clusters
31
How are staphylococcus differentiated?
coagulase test
32
Name an important coag negative staph.?
staph. epidermidis
33
What is the only coagulase positive staph.?
staph. aureus
34
Name 3 toxins produced by staph. aureus?
enterotoxin; SSSST; PVL
35
How do streptococcus sp. appear on gram staining?
gram positive cocci in chain
36
How are strep. sp. classified?
haemolysis
37
Name 2 bacterium that are alpha haemolytic strep.?
strep. pneumoniae and strep. viridans
38
What are the bacteria that are beta-haemolytic?
Group A, group B and group C, G
39
What bacteria is non-haemolytic?
enterococcus
40
how does partial haemolysis appear on a petri dish?
green
41
What enzyme do beta-haemolytic streptococci produce?
haemolysin
42
What is the purpose of having a dry skin surface?
dessication (drying out) of microbes
43
What is the purpose of sebum?
inhibit bacterial growth
44
What skin infections does staph. aureus cause?
```
boils and carbuncles
cellulitis
infected eczema
impetigo
wound infection
staph. scalded skin syndrom
```
45
What skin infections does strep. pyogenes cause?
```
infected eczema
impetigo
ceullitis
erysipelas (superficial form of cellulitis- raised red patches)
nectrotising fasciitis
```
46
What antibiotic is given for strep. pyogenes?
penicillin
47
What is necrotising fasciitis?
bacterial infection spreading along fascial planes below skin surface leading to rapid skin destruction
48
What are the 2 types of nectrotising fasciitis?
type 1- mixed
| type 2-group A strep
49
Where is tinea capitis found?
scalp
50
Where is tinea barbae found?
beard
51
where is tinea corporis found?
body
52
Where is tinea manuum found?
hand
53
Where is tinea unguium found?
nails
54
Where is tinea cruris found?
skin folds- groin; under the arm; under the breast
55
What other name is tinea pedis known as?
athletes foot
56
What type of tissue do dermatophytes infect?
keratinised tissues only-skin, hair and nails
57
what gives a dermatophyte infection its ring appearnace?
lesion grows outward and heals in the centre
58
What type of skin does fungus enter?
abraded or soggy skin
59
What is the most common dermatophyte causal organism?
trichophyton rubrum
60
What type of light can be used to diagnose fungal infections?
Woods light (fluroescence)
61
What is the name of the anti-fungal cream given?
clotrimazole
62
What systemic anti-fungal angents can be given?
terbinafine
| itraconazole
63
Where does candida cause skin infections?
in skin folds where area is warm and moist (candida intertrigo)
64
How are candida skin infections treated?
clotrimazole cream; oral fluconazole
65
What is scabies caused by?
sarcoptes scabiei
66
What is the norwegian scabies?
chronic crusted form which is highly infectious
67
What are the symptoms of scabies?
intensely itchy rash affecting finer webs, wrists and genital area
68
What is the treatment for scabies?
malathion lotion
| benzyl benzoate
69
What is the treatment for lice (pediculosis)?
malathion
70
What patients need single room isolation and contact precautions?
Group A strep infections
MRSA infection
Scabies (long sleeved g owns also required for norwegian scabies)
71
What virus causes chickenpox and shingles?
varicella zoster virus
72
What happens during chickenpox that allows the virus to reactivate as shingles?
Virus establishes latency in dorsal root ganglia
73
What is the progression of the rash found in chickenpox?
macules to papules to vesicles to scabs to recovery (centripetal-thickest on torso)
74
What is associated with chickenpox in addition to the rash?
fever and itch
75
What are the complications of chickenpox?
```
secondary bacterial
pneumonitis
haemorrhagic
scarring
encephalitis
```
76
What factors would predict chickenpox to be severe?
extremes of age; depressed cell mediated immunity
77
What does neonatal VZV happen secondary to?
chickenpox in mother in late pregnancy
78
How is neonatal VZV prevented?
varicella zoster immune globulin in susceptible women
79
What is the rash progression in shingles?
tingling/pain to erythema to vesicles to crusts
80
What is a compication of shingles?
post-herpetic neuralgia
81
What increases the chances of getting post-herpetic neuralgia?
eldery
| trigeminal distribution
82
Why is an opthalmogy referral required urgently if zoster affects the trigeminal nerve?
Shingles can cause keratitis- inflammation of the cornea
83
What is Ramsay-Hunt Syndrome?
When shingles affects CN7 and so causes vesicles and pain in the auditory canal and throat. Also causes facial palsy and if there is irritation of the 8th cranial nerve- deafness; vertigo and tinnitus
84
What is Ramsay-Hunt syndrome also known as?
geniculate or otic herpes zoster
85
Why is a vaccination for shingles given?
reduces incidence of shingles as well as post-herpetic neuralgia
86
What is happens during the first infection of herpes simplex?
gingivostomatitis
87
What are the symptoms of herpes simplex virus?
recurrent blistering rash at vermillion border
88
Where can herpes simplex spread to in the body?
fingers- herpetic whitlow
| eczema- eczema herpeticum
89
Which type of herpes simplex mainly causes oral lesions
HSV type 1
90
How does aciclovir work?
An analogue of guanosine and so is selectively incorporated into viral DNA inhibiting replication
91
What is the drawback of aciclovir?
Does not eliminate latent virus
92
What infections can cause erythema multiforme?
herpes simplex virus
| mycoplasma pneumoniae bacterium
93
What is molluscum contagiosum?
fleshy, firm umbilicated pearlescent nodules which are self limiting and common in children
94
How can molluscum contagiosum be treated?
liquid nitrogen
95
What virus causes warts?
HPV
96
How can warts be treated?
topical salicyclic acid
97
What age are warts most common?
children
98
What types of HPV are most common in warts/verrucas?
types 1-4
99
What types of HPV cause genital warts?
types 6 and 11
100
Which types of HPV cause cervical cancer?
types 16 and 18
101
What is herpangina?
blistering rash at the back of the mouth
102
What viruses cause herpangina?
enterovirus- coxsackie virus and echovirus
103
How can herpangina be treated?
usually self-limiting
104
What viruses cause hand, foot and mouth disease?
enteroviruses- esp. coxsackie
105
What age group typically gets hand, foot and mouth disease?
children
106
What virus causes erythema infectiosum?
human parovirus
107
What is the common name for erythema infectiosum?
slapped cheek disease
108
What are the symptoms of erythema infectiosum?
slapped cheek appearance which as it fades becomes a lacy macular rash on the body. headache; fever; arthralgias; sore throat
109
What is especially seen in adults with erythema infectiosum?
acute arthritis esp. in the wrists as the rash fades
110
What are the complications of parovirus?
spontaneous abortion
aplastic crises (sudden drop in haemoglobin)
chronic anaemia
111
How is parovirus diagnosed?
antibody testing - IgM
112
What is Orf?
virus of sheep "scabby mouth"
113
How does Orf present?
firm, fleshy nodule on hands of farmers
114
What is the first phase of a syphilis infection?
chancre- painless ulcers at site of entry
115
What is the secondary phase of syphilis infection?
red rash over body- which is prominent on soles of feet and palms of hands
mucous membrane- "snail track" ulcers
116
What is the tertiary phase of syphilis infection?
CNS; CVS; gummatous
117
What is syphilis caused by
bacterium- treponema pallidum
118
How is syphilis diagnosed?
blood test or swab of chancre for PCR
119
How is syphilis treated?
injections of penicillin
120
What is the vector in Lyme disease?
ticks
121
What bacterium causese Lyme disease?
Borrelia burgdorferi
122
What is the early presentation of Lyme disease?
erythema migrans
123
What is the late presentation of Lyme disease?
heart block; nerve palsies; arthritis
124
What is the therapy for Lyme disease?
amoxicillin or doxycycline
125
What is the lab confirmation for Lyme disease?
antibody blood test (mainly for late presentations)
126
What are the symptoms of Zika virus?
fever; rash (maculopapular); headaches; arthralgia; myalgia; non-purulent conjuctivitis
127
What is the vector for Zika virus?
mosquito
128
What are the complications of Zika virus?
microcephaly and guillain barre syndrome
