Clin Lab: STIs Flashcards

1
Q

Note

A

Many STIs can be asymp & are often underdx

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2
Q

Undx infx can lead to what significant complications in females?

A

PID & infertility

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3
Q

List common STIs

A

Chancroid
Chlamydia
Gonorrhea
Genital warts / HPV
Hepatitis A/B/C
Herpes simplex
HIV
Syphilis
Mycoplasma genitalium
Scabies and crab louse
Syphilis
Trichomonas

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4
Q

What is commonly tested/route for STIs

A

serum & wet prep/urine

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5
Q

We test serum for which STIs?

A
  • HIV
  • Syphilis
  • Hep A/B/C
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6
Q

We test wet prep/urine for which STIs?

A
  • Gonorrhea
  • Chlamydia
  • Trichomonas
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7
Q

Who do we test for HIV?

A

Everyone!!!
- Suspected acute infx
- Those at incr risk – yearly, maybe even quarterly
- All adults at least once
- All pregnant women, each pregnancy

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8
Q

What are some S/Sx of a suspected HIV acute infx pt?

A

Flu-like symptoms, sore throat in the right person

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9
Q

When do we test pregnant women for HIV?

A

at their first prenatal visit

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10
Q

What is the best test to detect HIV and how long is the window?

A
  • RNA
  • 5-7 days
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11
Q

What can diagnostics tests for HIV detect?

A
  • antibodies against HIV 1 or 2
  • HIV p24 antigen
  • HIV-1 RNA*
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12
Q

NOTE

A

Different HIV tests are used depending on acute infection vs chronic infection vs screening

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13
Q

Screening test for HIV

A
  • 3rd gen immunoassay
  • 4th gen immunoassay
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14
Q

What does the 3rd gen immunoassay for HIV measure?

A

Abs only
- IgG and IgM Abs

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15
Q

What does the 4th gen immunoassay for HIV measure?

A

Ab & PRO Ag
- IgG/IgM and P24 Ag

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16
Q

What are the FU tests/confirmatory test if HIV screening test is (+)?

A
  • HIV-1/HIV-2 Ab differentiation assay
  • HIV-1 RNA
  • Older -> Western blot (PRO electrophoresis)(HIV-1)
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17
Q

Further diagnostic testing in pts w/ HIV

A
  • CD4 T-Lymphocyte Count
  • HIV-RNA quantification (viral load)
  • Phenotypic & Genotypic Assays for Antiretroviral Drug Resistance
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18
Q

Diagnostic tests for acute HIV infx

A
  • 4th gen assay
    AND
  • HIV-1 RNA test

Often have (-) assay & (+) RNA test in acute infx

If both are (-)& there is high suspicion of infx, repeat in 1-2 wks

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19
Q

Laboratory Testing for HIV flow chart

A

DONE

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20
Q

Recommended Initial Tests: Dx of chronic HIV infx or screening in asymp ppl

A

4th gen assay

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21
Q

Recommended Initial Tests: Dx of acute HIV infx

A

4th generation assay & HIV-RNA detection

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22
Q

Recommended Initial Tests: Dx of HIV in infants born to HIV-infected mother

A

DNA PCR or HIV-RNA detection

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23
Q

Recommended Initial Tests: Prognosis

A

HIV-RNA quant & CD4 T-cell count

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24
Q

Recommended Initial Tests: Response to antiretroviral therapy

A

HIV-RNA quant & CD4 T-cell count

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25
Q

Recommended Initial Test: Antiretroviral drug resistance testing

A

Phenotypic and/or genotypic resistance assays

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26
Q

Recommended Initial Tests: blood donor screening

A

3rd gen assay & HIV-RNA detection

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27
Q

How is Hep B tested?

A

measure Hep B surface antigen, surface antibody &core antibody

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28
Q

Hep B Testing Results Chart
(Phase (5), HBsAg, Anti-HBc, IgM Anti-HBc, Anti-HBs)

A

DONE

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29
Q

Describe testing interpretation for Hep C

A
  • If (-), chronic infx is unlikely
  • If (+), measure Hep C RNA (PCR)
    –> If (+), chronic infx confirmed–> tx
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30
Q

Who do we screen for Hep B/C?

A

higher risk patients

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31
Q

What do we measure for Hep C testing

A

Hep C Antibodies (anti-Hep C)

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32
Q

Describe Hep C test interpretation

A
  • If (-), chronic infx is unlikely
  • If (+), measure Hepatitis C RNA (PCR)
    –>If (-), chronic infx unlikely
    –> If (+), chronic infx confirmed–> tx
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33
Q

What 2 tests can be done to detect syphilis?

A
  1. Direct visualization
  2. Antibody testing
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34
Q

Describe the protocol/results of the two antibody tests for syphilis?

A
  • If initial test is (-), no further testing is needed unless high suspicion for infx
  • If initial test is (+), need to do the other type of antibody test for confirmation
    –> Do test of opposite type: (+)/(+) tx for syphillis
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35
Q

Syphilis antibodies are usually detected by…

A

serum

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36
Q

Which STI requires testing of the CSF?

A

neurosyphilis

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37
Q

Name the 2 types of syphilis antibody test

A

Non-treponemal tests & Treponemal tests

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38
Q

Non-treponemal test detects…

A

serum reagin antibodies

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39
Q

What antigens are associated w/ non-treponemal testing?

A

cardiolipin/cholesterol

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40
Q

What happens to the non-treponemal titer as infx is resolved over time?

A

it decreases

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41
Q

What are the types of non-treponemal tests?

A
  • Rapid plasma reagin (RPR)
  • Venereal Dz Research Lab (VDRL)
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42
Q

Treponemal test detects…

A

antibodies against treponemal antigens

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43
Q

What happens to the treponemal titer?

A

remains (+) after infx resolved

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44
Q

What are the types of treponemal tests?

A
  • FTA-ABS (Fluorescent Treponemal Antibody – absorbed)
  • TP- EIA (T palladium ELISA)
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45
Q

If (-) non-treponemal (RPR or VDRL) test, what happens next?

A

no further testing necessary, unless strong suspicion for either very early primary infx or latent infx

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46
Q

If (-) treponemal (FTA-APS or TP-EIA), what happens next?

A

no further testing considered necessary

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47
Q

If either the non-treponemal/treponemal test is (+), what happens next?

A

perform confirmatory test of opposite type

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48
Q

(+) non-treponemal + high titer / positive treponemal means…

A

syphilis infx

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49
Q

(+) initial non-treponemal + low titer / negative FU treponemal means…

A

likely initial false (+)

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50
Q

(+) initial treponemal + (-) FU non-treponemal means…

A

either
- prior tx infx
- very early primary infx
- late infx

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51
Q

Syphilis screening flow chart

A

DONE

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52
Q

What organism causes Chlamydia?

A

Chlamydia trachomatis

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53
Q

Describe chlamydia trachomatis

A

Intracellular (GNID) pathogen of columnar epithelial cells

54
Q

Is chlamydia a urogenital infx?

A

YES usually, but can cause non-urogenital infx…
- conjunctivitis, pharyngitis, reactive arthritis, proctitis, lymphogranuloma venerum

55
Q

S/Sx of chlamydia

A

usually asymp
–> can have burning during urination &/or discharge

56
Q

Testing for chlamydia & describe how it is obtained

A
  • NAAT
    –> First-catch urine in men
  • vag/endocervical swab in women
57
Q

Describe Neisseria gonorrhea.

A

intracellular pathogen
–> gram (-) intracellular diplococci

58
Q

2 diagnostic tests for N. gonorrhea

A
  1. NAAT
  2. Gram stain & culture
59
Q

Describe N. gonorrhea gram stain & culture for males

A
  • gram stain of urethral exudate
    –>If Gram stain(+) for GNID = def dx

First catch urine

60
Q

Describe N. gonorrhea gram stain & culture for females

A

DON’T use gram stain of vaginal discharge
- use endocervical swab
- (+) GNID = presumptive diagnosis in female
Confirm w/ culture results

61
Q

What type of infx is gonorrhea?

A

non-urogenital

62
Q

Gonorrhea can cause which type of conditions(5)?

A
  • conjunctivitis
  • proctitis
  • pharyngitis
  • disseminated gonorrhea
  • septic arthritis
63
Q

Testing for gonorrhea

A
  • NAAT testing
  • Gram stain / culture (in some instances)
64
Q

What specimens can be used for gram stain/culture?

A
  • Synovial fluid
  • Blood cultures
  • Eye
65
Q

Site of disseminated gonorrhea.

A
  • joints (purulent septic arthritis)
  • heart (endocarditis)
  • bone (osteomyelitis)
  • brain (meningitis)
66
Q

Describe ailments of disseminated syndrome of gonorrhea.

A
  • arthritis-dermatitis
  • tenosynovitis,
  • migratory polyarthritis
  • painless skin pustules
  • often with fever/malaise as well
67
Q

List the prevalence of gonorrhea/chlamydia/mycoplasma genitalium (highest - lowest)

A
68
Q

Mycoplasma genitalium is a major cause of…

A

non-gonococcal urethritis

69
Q

How will a patient present w/ mycoplasma genitalium?

A

The same as a person w/ gonorrhea-chlamydia, but their testing will be (-) for those conditions

70
Q

Who do we test for mycoplasma genitalium?

A

anyone who you are testing for Gonorrhea/Chlamydia

71
Q

Testing for Mycoplasma genitalium
(men vs women)

A

NAAT
- first-catch urine for men
- vaginal swab for women

72
Q

Which herpes virus can cause genital herpes?

A

HSV 1 & 2

73
Q

Which HSV virus is more likely to cause oral herpes?

A

HSV-1

74
Q

Which HSV virus is more likely to cause genital herpes?

A

HSV-2

75
Q

How is HSV usually diagnosed?

A

clinical dx

76
Q

How does a HSV rash look?

A

Painful, grouped vesicles, on erythematous base

77
Q

Describe testing methods for HSV

A
  • Tzanck prep–> unroof young vesicle–> multi nucleated cells
  • Cell culture from early vesicular lesion gold standard
  • Viral PCR from lesion swab*
  • Direct fluorescent testing
  • Serum Ab testing
78
Q

Which HSV test can detect asymptomatic shedding of the virus?

A

viral PCR from lesion swab

79
Q

What is the most common STD in the US & the world

A

Human Papilloma Virus (HPV)

80
Q

What % of sexually active adults have been infected w/ HPV?

A

> 75%

81
Q

HPV is associated w/ what conditions?

A

ano/genital dysplasia & epithelial (squamous cell) CAs

82
Q

What conditions can HPV cause?

A
  • Condylomata accuminata (genital warts)–> non-CA
  • Cervical CA
  • Oropharyngeal CA
83
Q

HPV diagnostics

A

limited to cervical specimens

84
Q

What other testing can be done for HPV?

A

testing CA samples for HPV DNA

85
Q

What vaccine can be used to protect against strains of HPV & most likely ones to causes cervical cancer?

A

Gardasil

86
Q

What is the most common non-viral, non-bacterial STI in the US?

A

trichomoniasis

87
Q

What organism causes trichomoniasis?

A

Trichomonas vaginalis

88
Q

What are the testing options for Trichomoniasis?

A
  • direct visualization on wet prep
  • culture
  • Rapid antigen tests
  • NAAT
89
Q

NOTE

A

You have to see the trichomonas vaginalis & you have to see it moving to say its (+)

90
Q

How long does a trichomoniasis culture take?

A

about 48 hours

91
Q

What is the GS testing for trichomoniasis?

A

NAAT

92
Q

What is Leptothrix?

A

long bacteria often present with trichomonas
–> if seen you should also check for trichomonas vaginalis

93
Q

Is chancroid rare or common?

A

RARE

94
Q

Describe a chancroid.

A

Genital ulcers, often necrotic or erosive and painful

95
Q

What differentiates a chancroid ulcer from syphilis ulcer?

A
  • chancroid is painful
  • syphilis is painless
96
Q

Testing for chancroid

A
  • Culture
  • PCR

(only available through regional labs)

97
Q

Organism that causes crab louse

A

Pthirus pubis

98
Q

Crab louse dz is called…

A

Pediculosis pubis

99
Q

How does crab louse (pthirus pubis) survive?

A

feeds on human blood

100
Q

How will a pt present w/ crab louse?

A

itching

101
Q

Does crabs louse embed in the skin or stay on the surface?

A

stays on surface
- eggs are on the pubic hairs

102
Q

Crab Louse Dx

A

visualization of louse or eggs

103
Q

What organism causes scabies?

A

Sarcoptes scabiei

104
Q

Describe a scabies rash

A

Pruritic papular rash

105
Q

Does scabies embed in the skin or stay on the surface?

A

embedded into skin

106
Q

Scabies Dx

A

skin scraping

107
Q

Indications for a vaginal wet prep

A
  • Vaginal discharge/odor
  • Vulvar or vaginal itching
  • Vaginal or lower abdo pain
108
Q

Describe the vaginal wet prep procedure

A
  • Cotton swab used to get sample of vaginal discharge/cervix
  • Swab placed in test tube in several drops of saline
  • One drop is placed on slide w/ coverslip & examined w/ light microscope
  • KOH test
109
Q

Which part of the vagina should you exam for wet prep and why?

A

Look at posterior fornix for any pooling of discharge or clumps

110
Q

Vaginal wet prep will give you the following results…

A
  • epithelial cells/types
  • WBCs
  • Evidence of infx
111
Q

What are the layers of vaginal epithelium? (outer to inner)

A
  • superficial cells
  • Intermediate cells
  • Parabasal cells
  • Basal cells
112
Q

Describe what seen w/ Superficial Squamous Epithelium

A
  • Normal Squamous Epithelium
  • Normal Flora (lactobacilli)
  • a few WBCs
113
Q

Describe to look of Superficial Squamous Epithelium

A
  • “fried eggs”
  • irregular borders
  • Mostly cytoplasm, nucleus appears small
114
Q

Parabasal squamous epithelium is seen in…

A
  • estrogen deficiency
  • traumatic exfoliation of vaginal lining
    -vaginal wall atrophy
115
Q

Parabasal Squamous Epithelium are similar to what cells in the kidney system?

A

transitional cells

116
Q

Seeing basal squamous epithelium indicates…

A

extremely atrophic or deeply ulcerated vaginal mucosa

117
Q

Describe basal squamous epithelium

A

Simple cuboidal cells
–> when free they look more rounded

118
Q

Basal Squamous Epithelium are similar to what cells in the kidney system?

A

renal tubular epithelial cells

119
Q

Which organisms elicit an immune response?

A
  • Trichomonas
  • Candida
  • Herpes
  • Gonorrhea
  • Chlamydia
120
Q

Which bacteria does NOT cause an immune response?

A

Gardnerella vaginalis

121
Q

What is the most common cause of a yeast infx?

A

candida albicans

122
Q

Describe what is seen when a person has a yeast infx?

A
  • budding yeast &/or hyphae
  • Small amount normally found; overgrowth is infx
123
Q

Is a yeast infx an STI?

A

NO

124
Q

Testing used for a yeast vaginal infx?

A

KOH test

125
Q

What bacteria causes bacterial vaginosis?

A

Gardnerella vaginalis

126
Q

Describe bacterial vaginosis.

A

NOT an STI
- an overgrowth of normal flora

127
Q

Does bacterial vaginosis have a WBC response?

A

NO

128
Q

Testing proof of bacterial vaginosis

A

“Clue cells”

129
Q

Bacterial vaginosis can result in…

A

urethritis

130
Q

Describe clue cells

A

bacteria attaches itself to the squamous cells & obscures the edges; looks sandy in appearance

131
Q

What can be the cause of whitish clumps & vaginal itching not due to yeast infx?

A
  • azithromycin
  • douching
132
Q

What is actually causing the white clumps not caused by yeast infx?

A

sheets of squamous epithelial cells