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CLS 753 > Micro - STDs & Syphilis > Flashcards

Micro - STDs & Syphilis Flashcards

1
Q

Reproductive tract infections can be transmitted in 3 different ways…

A

Endogenous infections - overgrowth of normally present organisms (ie bacterial vaginosis)

Iatrogenic infections - introduced by medical procedures

STDs - during sexual intercourse

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2
Q

Are most bacterial STDs curable or incurable? Are most viral STDs curable or incurable?

A

Curable - syphilis, chancroid, gonorrhea, chlamydial infection, trichomoniasis (parasite)

Incurable - HIV/AIDS, HPV, Hepatitis B, genital herpes

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3
Q

Curable STDs that are ulcerative (2)

A

Syphilis

Chancroid

-genital sores, ulcers

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4
Q

Chancroids are caused by this bacteria…

A

Haemophilus ducreyi

  • gram negative small rods
  • looks like train tracks or school of fish
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5
Q

Haemophilus ducreyi requires which factor(s)?

A

X and V

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6
Q

Curable STDs that are non-ulcerative (3)

A

Gonorrhea

Chlamydia

Trichomoniasis (parasite)

-usually discharge or asymptomatic

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7
Q

In women, untreated STDs can migrate upwards, causing this condition…

A

PID - pelvic inflammatory disease

-including endometritis

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8
Q

In the US, the most common STD is… What is the organism that causes the disease?

A

Chlamydia
-alongside gonorrhea

Chlamydia trachomatis

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9
Q

Chlamydia trachomatis is an obligate ___

A

Intracellular bacteria

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10
Q

Can Chlamydia trachomatis be gram stained? Why or why not?

A

No

No peptidoglycan

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11
Q

Chlamydia trachomatis causes infection to these organs (2)

A

Genitals

Eyes

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12
Q

What are the 2 forms of Chlamydia trachomatis? Which form is bigger?

A 
EB = elementary body
RB = reticulate body

RB is bigger

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13
Q

Which form of Chlamydia trachomatis is infectious?

A

EB

-binds to host cell receptor and endocytosed

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14
Q

Which form of Chlamydia trachomatis is metabolically active and which is inactive?

A

EB = inactive

RB = active

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15
Q

Two types of specimens sent to the lab for chlamydia are…

A

Swab from urethral/vaginal discharge

Urine
-for newer amplification tests (PCR)

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16
Q

Chlamydia cultures are usually only done under these circumstances…

A

As confirmation the positive test
-backup for the faster tests

When substances in sample interfere with amplification tests

When medico-legal issues are involved
-child abuse

17
Q

What type of cell line is used when culturing Chlamydia trachomatis?

A

McCoy cell line

  • mouse fibroblast cells
  • culture on coverslip in nutrient medium, add sample and centrifuge
  • coverslip can be stained after incubation
18
Q

What are the 3 types of stains used to detect Chlamydia trachomatis after culturing the specimen sample with McCoy cells?

A

Iodine - inclusion bodies look dark brown
-use positive/negative controls

Giemsa - look for EB/RB inclusion bodies

DFA - infected cells fluoresce green
-very accurate and sensitive

19
Q

When gonorrhea specimens are collected, one of these two transport media should be used…

A

Stuart’s charcoal medium

OR

Amie’s charcoal medium

20
Q

What is the confirmatory test to detect a gonorrhea infection for males? For females?

A

Males = gram stain showing intracellular diplococci
-no culture needed

Females = selective media since gram stain is NOT diagnostic
-diplococci confused with anaerobes or short gram negative rods in genital tract

21
Q

What are the two important selective media for gonorrhea?

A

Modified Thayer-Martin (MTM)
-modified chocolate agar

NYC medium
-clear medium

-incubation system = JEMBEC plates

22
Q

Why is MTM the preferred medium to isolate gonorrhea?

A

Contains vitamins and antibiotics to suppress normal flora

23
Q

What is the purpose of culturing gonorrhea on a biplate containing both MTM and chocolate agar?

A

Some gonorrhea strains won’t grow on MTM and will grow on chocolate
-streak on both to avoid delays

24
Q

Neisseria gonorrhoeae (and meningitidis) are catalase ___ and oxidase ___. Differentiation of Neisseria spp is based upon…

A

Positive

Positive

Sugar profile (ie CarboFerm)

25
Q

Should we perform an AST on Neisseria spp?

A

Yes

-highly antimicrobial resistant now

26
Q

Trichomoniasis is caused by this organism…

A

Trichomonas vaginalis

27
Q

What specimen sample should we collect for Trichomoniasis?

A

Urine

-used to be swab sample or discharge

28
Q

What are two ways that Trichomoniasis can be detected…

A

Wet mount of urine sample

  • sensitive organism
  • can round up, looking like a WBC

Dipstick rapid test (OSOM Trichomonas Rapid Test)

29
Q

Bacterial vaginosis is best diagnosed by…

A

Gram stain of vaginal discharge and look for clue cells

  • BV is not exclusively an STD
  • also use these criteria: fishy odor (whiff test), pH >4.5, lack of Lactobacilli
30
Q

What agent causes syphilis?

A

Treponema pallidum

31
Q

Can Treponema pallidum be gram stained? Why or why not?

A

No

Spirochete

32
Q

Is Treponema pallidum motile? Can it be cultured in vitro?

A

Yes

No
-can grow on armadillo’s feet

33
Q

What are the stages of a syphilis infection?

A

Primary

Secondary

Latent

Tertiary

  • survives inside phagocytes
  • spread throughout any organ in the body
34
Q

What kind of microscope should we use to see Treponema pallidum?

A

Darkfield microscopy

35
Q

What methods are used to diagnose primary syphilis? Secondary? Latent? Tertiary?

A

Primary = darkfield microscopy, DFA, serology

Secondary, latent, tertiary = serology only

-darkfield microscopy and direct fluorescent antibody staining only possible during primary infection

36
Q

What are the 2 categories of serological testing done for syphilis? Which one do we start with first?

A

Non-treponemal test = start with this first. Screening test
-easy, inexpensive

Treponemal test

37
Q

Non-treponemal tests include (2)… What do the tests detect?

A

VDRL
RPR

non-specific antibodies that react to cardiolipin
-false positives occur = old age, TB, Chagas’, leprosy, autoimmune

38
Q

Once a patient is positive for a non-treponemal test, what do we do next? Once a patient is CONFIRMED to have syphilis, what test is used to monitor their condition?

A

Treponemal test = confirmatory test

Non-treponemal test

  • VDRL or RPR. Do one or the other, do not switch
  • titer falls with successful treatment
  • antibodies there for life at detectable levels
39
Q

What are two commonly used treponemal tests?

A

FTA-ABS (fluorescent treponemal antibody absorption)

MHA-TP (microhemagglutination test for T. pallidum)

  • test results remain positive
  • tests cannot be used to assess treatment response or reinfection; use non-treponemal test instead

CLS 753 (12 decks)

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