Microbiology Flashcards
1
Q
what organism predominates normal vaginal flora
A
lactobacillus spp
2
Q
give 2 examples of lactobacillus that are part of the normal vaginal flora
A
lactobacillus crispatus
lactobacillus gensenii
3
Q
how are lactobacillus protective
A
produce lactic acid +/- hydrogen peroxide making the vagina acidic so pathogenic organisms dont grow
4
Q
give 3 other examples of normal vaginal flora
A
group B b-haemolytic strep
small no of candida sp (mainly albicans)
strep viridans
5
Q
give 4 PDFs for candida infection
A
recent antibiotic tx
high oestrogen levels
poorly controlled diabetes
immunocompromised (non-albicans)
6
Q
how does candida infection present
A
intensely itchy white vaginal discharge
7
Q
how is candida infection diagnosed
A
high vaginal swab of posterior fornix of vagina for culture
8
Q
most candida infections are what type
A
albicans
9
Q
how is candida infection treated
A
topical clotrimazole pessary or cream (OTC) oral fluconazole (one dose)
10
Q
what is the issue with treating non-albicans candida infection
A
more likely to be azole resistant
11
Q
what kind of candida would cause typical spotty rash on penis which is not an STI
A
candida balanitis
12
Q
what kind of organism is gonorrhoea
A
gram negative diplococcus
13
Q
gonorrhoea diplococci look like
A
2 kidney beans facing eachother
14
Q
does gonorrhoea appear intra or extracellular on gram film
A
intracellular
15
Q
how does gonorrhoea become intracellular
A
easily phagocytosed by polymorphs
16
Q
gonorrhoea is a fastidious organism - what does this mean
A
doesn’t survive well in less than ideal conditions
17
Q
where can gonorrhoea infect
A
mucous membranes of the ... urethra rectum throat eyes endocervix
18
Q
how does gonorrhoea of the rectum or throat present
A
usually asymptomatic
19
Q
how does gonorrhoea replicate
A
attaches to host epithelial cells and is endocytosed into the cell to replicate within the host and then released into subepithelial space
20
Q
gonorrhoea is more/less common than chlamydia and is more common in women/men
A
less common than chlamydia
more common in men
21
Q
how does gonorrhoea present in males
A
purulent urethral discharge
dysuria
22
Q
what % of gonorrhoea in males in asymptomatic
A
10
23
Q
how does gonorrhoea present in females
A
purulent urethral discharge
dysuria
pelvic pain
24
Q
what % of gonorrhoea in females is asymptomatic
A
50
25
how is gonorrhoea diagnosed
NAAT screening test for C + G
26
what sample is used for gonorrhoea dx for NAAT in males
first pass urine
27
what sample is used for gonorrhoea dx for NAAT in females
vulvovaginal swab
28
gonorrhoea can also be cultured on what agar
selective agar plate - suppresses growth of normal flora - kills competitors
29
in what case would you not need to use selective agar
when no competing flora is expected e.g. synovium
30
why is culture not done in a GP
only done in SRHC as if in GP organism dies on way to lab
31
culture of gonorrhoea can be done of what samples
endocervical, rectal, throat swabs
| not high vaginal swabs
32
what is an advantage of doing a culture
can test antibiotic susceptibility
33
what is the treatment for gonorrhoea
IM ceftriaxone + azithromycin
34
what is used if IM is CI to treat gonorrhoea
cefixime oral
35
when should a test of cure be done for gonorrhoea
at least 2 weeks later
36
there is a higher risk of ____ to ___ transmission of gonorrhoea than ____ to ____
male to female than female to male
37
what is the commonest STI in the UK
chlamydia trachomatis
38
what kind of organism is chlamydia
gram negative obligate intracellular bacterium
39
what does obligate intracellular bacterium mean
cannot live/reproduce outside host cell
40
what word describes the life cycle of chlamydia
biphasic
41
what colour does chlamydia stain
doesnt stain
42
why does chlamydia not stain
no peptidoglycan in the cell wall - typical lipopolysacarhide
43
why does chlamydia not stain
no peptidoglycan in the cell wall - typical lipopolysaccharide wall of GN bacteria
44
what are the 3 serological groups of chlamydia
serovars A-C
serovars D-K
serovars L1-L3
45
A-C causes what
trachoma
46
D-K causes what
genital infection
47
L1-L3 causes what
lymphogranuloma venereum - infection of the lymph nodes
48
who gets LGV
MSM
49
how does LGV present
usually presents in MSM with proctitis
- rectal pain/discharge/bleeding
- tenesmus
50
with LGV there is a high risk of what
concurrent STI e.g. HIV
51
what can chlamydia infect
```
urethra
rectum
throat
eyes
endocervix
```
52
what age group has the highest incidence of chlamydia
20-24 year olds
53
how does chlamydia present in males
```
watery urethral discharge
dysuria
urethritis
epididymo-orchitis
proctitis (LGV)
```
54
what % of males with chlamydia are asymptomatic
50%
55
what % of females with chlamydia are asymptomatic
70%
56
how does chlamydia present in females
post-coital or IM bleeding
lower abdominal pain
watery discharge
dyspareunia
57
the NAAT test is highly ____ and ____
sensitive and specific
58
what samples are taken for a NAAT test in females
vulvovaginal swab
59
what samples are taken for NAAT test in males
1st pass urine
60
what samples are taken for NAAT test in a symptomatic female (chlamydia)
high vaginal swab or endocervical swab
61
if chlamydia is transmitted to neonate it can cause
conjunctivitis
| pneumonia
62
when can a NAAT test be done for chlamydia
2 weeks post exposure
63
what is the treatment for chlamydia
doxycycline 100mg bd x 7 days
64
what is the risk of tubal blockage after one episode of chlamydia
10%
65
what is the risk of tubal blockage after 3 episodes of chlamydia
50%
66
what % of PID is due to chlamydia
50%
67
what is mycoplasma genitalium
non-gonococcal STI that can cause PID
68
how is mycoplasma genitalium dx
NAAT - VVS or FPU
| high levels of macrolide
69
mycoplasma genitalium presents how
usually asymptomatic carriage
70
what kind of organism is trichomonas vaginalis
single celled protozoal parasite
71
how does trichomonas vaginalis divide
binary fission (no cyst form is known
72
how is trichomonas vaginalis transmitted
STI or inanimate source e.g. sex toy
73
how does trichomonas vaginalis present in males
urethritis
74
how does trichomonas vaginalis present in females
vaginal discharge and irritation
75
how is trichomonas vaginalis dx
HVS for microscopy
| no good test for males
76
how is trichomonas vaginalis treated
oral metronidazole
77
what is the pathogenesis of bacterial vaginosis
lack of balance - normal flora replaced by anaerobic bacteria
78
give 2 examples of anaerobic organisms that replace normal flora in bacterial vaginosis
gerdernella vaginalis
| mobiluncus
79
what cells are seen in bacterial vaginosis
clue cells
80
what are clue cells
absence of bacilli and replacement with clumps of coccobacilli which coat some vaginal epithelial cells obscuring edges (clue cells) and obscuring normally clear cytoplasm
81
how does bacterial vaginosis present
intensely smelly frothy bubbly vaginal discharge
| positive whiff test
82
what is the positive whiff test
adding 10% KOH to discharge elicits amine like fishy odour
83
the vaginal pH in bacterial vaginosis becomes more
alkaline
| > 4.5
84
the vaginal pH in bacterial vaginosis becomes more
alkaline
| > 4.5
85
in bacterial vaginosis there is a ___ level of polymorphonuclear leukocytes
few
| high number would suggest coincidental infection possibly trichomoniasis or bacterial cervicitis
86
there is an increased risk of what with bacterial vaginosis
HIV contraction
| PROM and preterm delivery
87
what is the treatment of bacterial vaginosis
metronidazole 7 days
88
what causes pubic lice
Phthirus pubis
89
how is pubic lice contracted
close genital skin contact
90
how long do male lice live for
22 days
91
how long do female lice live for
17 days
92
why are pubic lice itchy
bite skin and feed on blood
| female lice lay eggs on hair
93
how is pubic lice treated
malathion lotion
94
how is sensitivity calculated
true positive / true positive + false negative
95
how is specificity calculated
true negative / true negative + false positive
96
how is positive predictive value calculated
true positive / true positive + false positive
97
how is negative predictive value calculated
true negative / true negative + false negative
98
gonococci that infect the male urethra produce an intense ______ response leading to purulent discharge
neutrophil
99
STIs tend to
coexist
100
is reinfection common
yes
101
genital ulcers greatly increases risk of what
acquiring HIV
102
what 2 STIs tend to co-exist
NG and CT
103
what organism causes syphilis
treponema pallidum
104
what kind of organism is treponema pallidum
spirochaete
105
what 5 ways can syphilis be transmitted
```
STI
during birth
trans-placental
blood transfusion
non-sexual transmission to health care workers
```
106
what are the 4 stages of syphilis
primary lesion
secondary stage
latent stage
late stage
107
what is chancre
painless ulcer that is a primary lesion in syphilis
108
what is the incubation period of a primary syphilis lesion
21 days
109
how does primary lesion of syphilis progress
organism multiplies at the innoculation site and gets into blood stream
110
non-tender local lymphadenopathy is what stage of syphilis
primary lesion
111
will chancre need treatment
will heal without treatment
112
90% of primary syphilis lesions are found where
genital
113
what happens in the secondary syphilis stage
large no of bacteria circulating in blood with multiple manifestations at different sites
114
what happens in the secondary syphilis stage
large no of bacteria circulating in blood with multiple manifestations at different sites
115
what are some examples of secondary lesions (6)
```
snail track ulcers
generalised rash (macular, follicular or pustular)
flu like symptoms
lesions of mucous membranes
generalised lymphadenopathy
patchy alopecia
```
116
where is the generalised rash of secondary syphilis found
palms and soles mainly
117
what is condylomata lata
highly infectious lesion in syphilis found on genitals - exudes a serum teaming with treponemes
118
what is the incubation period of secondary syphilis
6 weeks to 6 months
119
what are the symptoms of the latent stage of syphilis
no symptoms
120
the latent phase can be subdivided into early latent and late latent
of the 2 which is infectious
early latent - infectious
| late latent - non-infectious
121
what is seen in the late stage of syphilis
cardiovascular or neurovascular complications many years later
122
what stages of syphilis are infectious
primary lesion
secondary stage
early latent
123
what gait is seen in the late stage of syphilis
high stamping gate
124
what causes the high stamping gate seen in the late stage of syphilis
loss of proprioception due to tarbes so rely on ears to find out where feet are
125
what is tarbes
slow degeneration of neural tracts (particularly DCML) in syphilis - loss of touch, vibration and proprioception
126
dissemination occurs early/late in syphilis
early
127
what subspecies of treponema causes syphilis
pallidum
128
what subspecies of treponema causes Yaws
pertenue
129
what subspecies of treponema causes bejel
endemicum
130
what subspecies of treponema causes pinta
carateum
131
does syphilis stain with gram stain
no
132
can syphilis be grown in artificial culture
no
133
how is syphilis tested
PCR or serological blood test to detect antibodies
134
what does the baseline blood test for suspected syphilis test for
(ELISA test)
syphilis IgM and IgG
135
ELISA test is carried out on what specimen
clotted blood specimen
136
what 3 ways can primary syphilis be tested
dark ground microscopy
PCR
IgM
137
how can secondary and tertiary syphilis be tested
serology
138
what are some specific serological tests for syphilis
TPPA
IgM ELISA
INNO-LIA
FTA-abs
139
what test is +ve for life in syphilis
TPPA (treponema pallidum particle agglutination)
140
what test screens for syphilis
IgM ELISA
141
what is the treatment of syphilis
benzylpenicillin (injectable penicillin)
142
can you check syphilis sensitivities
no because it cant be grown but syphilis remains very sensitive to penicillin
143
what happens if someone is allergic to penicillin but has syphilis
desensitisation
144
what is the dose time ratio of syphilis
very low dose but must be exposed for a long time
145
what is the reason for the dose time ratio of syphilis
slow rate of replication
146
what is a nick name for syphilis and why
the great imitator
| mimics other diseases
147
what is a nick name for syphilis and why
the great imitator
| mimics other diseases
148
what type of HSV causes cold sores
both can
| Type 1 more common
149
describe the herpes simplex virus
enveloped virus containing double stranded DNA
150
how is HSV transmitted
close contact with someone shedding the virus (genital - genital or oropharyngeal - genital etc)
151
describe the pathogenesis of HSV
virus duplicates in epidermis and dermis and gets into sensory nerve endings and autonomic nerve endings
152
inflammation at nerve endings due to HSV causes what
intensely painful multiple small vesicles which are easily deroofed
153
how may primary infection of HSV present
asymptomatic or very florid
154
HSV migrates where
sacral root ganglion and hides from immune system
155
HSV can ____ causing recurrent genital herpes attacks
reactivate
156
can intermittent virus shedding occur in the absence of symptoms of HSV?
yes
157
what is the incubation period of primary HSV infection
3-6 days
158
what is the duration of primary HSV infection
14-21 days
159
how does primary HSV present
```
blistering and ulceration of external genitalia
pain
external dysuria
vaginal or urethral discharge
local lymphadenopathy
```
160
what are the HSV prodromal symptoms
fever and myalgia
161
recurrent infection is seen more with HSV
2
162
how often does HSV 2 recur
every 2-3 months
163
how often does HSV 1 recur
every 1-2 years
164
HSV recurs more/less as time goes on
less
165
recurrent HSV infection presents as
unilateral small blisters and ulcers
| minimal systemic symptoms that resolve within 5-7 days
166
how is HSV diagnosed
swab of base of deroofed blister in viral transport medium for PCR
167
how is HSV diagnosed between recurrences
no good test - serology IgG but not routinely used
168
what is the treatment of HSV
aciclovir PO 400mg TDS 5 days
| famciclovir/valaciclovir
169
what can be used for pain relief in HSV
topical lidocaine 5% ointment
| saline bathing
170
viral shedding is higher with HSV
2
171
viral shedding is more frequent during which year of HSV infection
1st year
172
viral shedding occurs more in people with more/less frequent recurrences
more
173
what is done if primary attack of HSV occurs in 3rd trimester of pregnancy
c section
174
what is the risk of transmission if primary attack of HSV occurs in 3rd trimester of pregnancy
50%
175
HSV transmitted to a neonate would cause what
localised CNS or diseminated disease (latter more common in preterm infants and exclusively in primary infection)
176
do transplacental antibodies stop HSV spreading to brain of neonate
no
177
what is done for pregnant women with recurrent HSV attacks
suppressive therapy and advised risk of transmission is very low
178
what is the most common viral STI in the UK
HPV
179
what is the lifetime risk of acquiring HPV
80%
180
describe HPV
major capsid protein (L1) surrounds viral nucleic acid (DNA)
181
how many types of HPV are there
over 200
182
how many types of HPV infect anogenital epithelium
> 40
183
what types of HPV cause anogenital warts
6 and 11
184
what types of HPV cause palmar and plantar warts
1 and 2
185
what types of HPV cause cellular dysplasia / intraepithelial neoplasia
16 and 18
186
can you get HPV from asymptomatic carrier
yes
187
is transmission of more than 1 type common
yes
188
what is the incubation period of HPV
3 weeks - 9 months (average 3 months)
189
what % of HPV warts spontaneously clear
20-35%
190
what % of HPV clears with treatment
60%
191
what % of HPV persists
20%
192
what types are vaccinated against
6 11 16 and 18
193
who is vaccinated
girls ages 11-13
boys S1 and S2
MSM
194
what is the 1st line treatment of HPV
podophyllotoxin (warticon)
195
what is the 2nd line treatment of HPV
imiquimod (aldera)
196
what is the 3rd line treatment of HPV
cryotherapy/electrocautery
197
how is HPV diagnosed
clinically
198
how does acute bacterial prostatitis present
symptoms of UTI but may also have lower abdo pain/ back perineal pelvic pain and tender on prostate exam
199
what UTI organisms cause acute bacterial prostatitis
e coli and other coliforms
| enterococcus sp
200
what STI organisms cause acute bacterial prostatitis
chlamydia
| gonorrhoea
201
how is acute bacterial prostatitis diagnosed
clinically
MSSU (mid stream specimen of urine) for culture and sensitivity
FPU if think STI
202
what is the treatment of acute bacterial prostatitis
ciprofloxacin or trimethoprim 28 days
