Sexually Transmitted Infections

Question 1

What is the leading reported infectious disease in the U.S., and who has the highest prevalence?

Answer 1

Chlamydia trachomatis, highest among sexually active teenagers

Question 2

What are the infectious and metabolically active forms of Chlamydia?

Answer 2

Infectious - elementary body

Non-infectious - Reticulate body

Question 3

Which body has stainable inclusion bodies and why?

Answer 3

Reticulate body, because it synthesized large amounts of glycogen which can be stained via iodine

Question 4

What two diseases is Chlamydia a major risk factor for in women and why?

Answer 4

1. Reactive arthritis - often implicated

2. Pelvic inflammatory disease - develops in 20-40% of women, leads to ectopic pregnancy / infertility

Question 5

What are typical symptoms of Chlamydia infection in women?

Answer 5

You can have cervicitis, salpingitis, or urethral syndrome, but it is asymptomatic in >50% of cases

Question 6

What does Chlamydia cause in men?

Answer 6

Urethritis (urethral discharge easier to detect in men)
Epididymitis
Orchitis

Also: Reactive arthritis

Question 7

What infection does Chlamydia cause in neonates?

Answer 7

Inclusion conjunctivitis or pneumonia

Question 8

Why does Chlamydia cause PID?

Answer 8

Tissue fibrosis occurs as a result of chronic or recurring infection with strong inflammatory immune responses but no immunity to re-infection

Question 9

What is Lymphogranuloma venereum? What Chlamydia serotypes cause this?

Answer 9

L1, L2, and L3 (for lympho).

Small, painless ulcers on genitals, leads to swollen, painful inguinal lymph nodes that ulcerate and cause buboes.

Common in MSM

Question 10

What Chlamydia serotypes cause follicular conjuncitivitis?

Answer 10

Occurs chronically in africa.

Serotypes A, B, C
A = Africa
B = Blindness
C = Chronic

Question 11

What Chlamydia serotypes cause urethritis / PID?

Answer 11

D - K = Everything else.

Question 12

How is Chlamydia diagnosed?

Answer 12

Collection of infected epithelial cells from infection site, then PCR from vaginal swab or urine specimen (men)

Question 13

Why are Chlamydia and Neisseria gonorrhoeae infections common co-infections?

Answer 13

Gonococcal infections facilitate transmission of Chlamydia

Question 14

What are the general characteristics of gonococcus? What cells do they grow in

Answer 14

Gram negative diplococci with fastidious growth requirements, thus they are facultatively intracellular in PMNs (neutrophils) or epithelial cells

Question 15

What is a Thayer-Martin plate and why are they used to isolate gonococcus?

Answer 15

Chocolate agar plate (fastidious growth requirements, like H. influenze) + antibiotics which reduce other GU flora which could grow with it

Question 16

What is the primary adhesion virulence factor of N. gonorrhoeae and how does it attach and evade host immune response?

Answer 16

Pili - binds human CD46 membrane receptor

1. RNA level = Slipped strand mispairing - Change the pilus length and create pilus plus and pilus minus (do not survive) phenotypes
2. DNA level = Antigenic variation, PilE = expression, must recombine with pilS (several loci) to express different amino acid sequence in pilus protein

Question 17

What causes a major inflammatory response in gonorrhea?

Answer 17

Lipo-oligosaccharide (LOS), the equivalent to LPS but the gonorrhea variant. Can be sialyated to confer serum resistance and block neutrophil attachment

This causes major of damage in disease

Question 18

What does gonorrhea in men look like?

Answer 18

Urethra is primary site of infection, dysuria and purulent urethral discharge (as opposed to mucoid discharge of chlamydia)

Question 19

What does gonorrhea look like in women?

Answer 19

Often asymptomatic, endocervix is primary infection site, can cause vaginal discharge, pelvic pain, and urgency / frequency

Often asymptomatic and cause infertility due to salpingitis

Question 20

What is disseminated gonococcal infection (DGI) and what does it cause?

Answer 20

Rare, causes an arthritis-dermatitis syndrome, with hemorrhagic lesions around feet and monoarticular arthritis

Question 21

How can gonorrhea be detected in men vs women in the lab?

Answer 21

Symptomatic men = gram stains. Does not work for symptomatic women (need PCR).

Typically, just culture urethral discharge (men) or cervical swabs (women) on Thayer-Martin

Diplococci within PMN = diagnostic for men

Question 22

Are gonorrhea oxidase positive?

Answer 22

Yes, oxidase positive

Question 23

What is the morphology / characteristics of Treponema pallidum? How can it be seen?

Answer 23

Gram negative spirochete, obligate human pathogen which is very environmentally sensitive

Can be seen via darkfield microscopy

Question 24

Can you get syphillis transplacentally?

Answer 24

Yes - fetus is susceptible any time during gestation

Question 25

How does syphillis disseminate before a primary lesion occurs?

Answer 25

Disease of blood vessels and perivascular lymphatics. Pathogen invades mucous membranes and travels to perivascular lymphatics and lymph nodes / systemic circulation, before developing a primary lesion

Question 26

What is primary syphillis? Where do they appear? When do they heal?

Answer 26

A "painless!!" chancre 3-4 weeks post contact, which is round, hard, with defined edges. Appear on external genitalia, anal area, or lips. Females may have them on cervix so they cannot be seen. Visualize fluids of darkfield microscopy Will heal spontaneously in 4-6 weeks

Question 27

When does secondary syphilis develop and what are the symptoms? This is when the patient comes in for treatment typically

Answer 27

Develops 2-10 weeks following healing of primary lesion Symptoms: fever, sore throat, rash, skin lesions on palms and soles is very diagnostic It can be cleared by immune system or go latent S(econdary) = Systemic

Question 28

What is latent syphilis?

Answer 28

No signs and symptoms of syphilis, but patient is seroreactive. Antibiotic therapy will prevent progression to tertiary syphilis. ~40% of untreated patients will get tertiary, in 5 years at the earliest (15-20 is most common)

Question 29

What is tertiary syphilis marked by?

Answer 29

Gummas - Granulomatous lesions of skin, bone, and joints due to host immune response. Neurosyphilis - Argyll-Robertson pupils (constricts on accommodation but does not react to light), tabes dorsalis, dementia, optic atrophy, seizures Cardiovascular syphilis - Aortic aneurysm

Question 30

Is the organism often found in secondary and tertiary syphilis lesions?

Answer 30

Secondary - foot and palm rash = yes, very infectious | Tertiary - gummas - no, just host immune response typically

Question 31

What typically happens to babies afflicted with congenital syphilis with respect to delivery time?

Answer 31

They are typically premature, with low birth weight. May exhibit rhinitis, pneumonia, and failure to thrive 3-8 weeks post birth

Question 32

For severe cases of congenital syphilis, what are some of the pathopneumonic exam findings?

Answer 32

1. Hutchinson's teeth - notched teeth 2. Saddle nose - bend in nose 3. Hard palate defect 4. Short maxilla 5. Protruding mandible 6. Rhagades - linear scars on edge of mouth 7. CN8 deafness

Question 33

How does the VDRL / RPR test work?

Answer 33

It uses a cardiolipin to detect anti-cardiolipin antibodies in the patient's serum, which can indicate the patient has syphilis. VDRL is quantitative and should fall after resolution of infection. Works because: Syphilis infection produces nonspecific antibodies that react with cardiolipin, a normally mitochondrial lipid which is produced in bacteria.

Question 34

What are some sources of false positives for the VDRL test?

Answer 34

Other things which produce antibodies which react with cardiolipin. I.e: V: Viral infection D: Drugs R: Rheumatic fever / heart disease L: Lupus / Leprosy Very sensitive for syphilis, but not specific

Question 35

What is the Treponema-specific serologic diagnostic test?

Answer 35

Direct detection of antibody to T. palladium, as in fluorescence treponemal antibody absorption test - FTA-ABS Specific but not sensitive. Also not affected by treatment (will not fall)

Question 36

What is one really good test for seeing if T. pallidium is there?

Answer 36

Tp-PCR - treponema PCR

Question 37

What is one STI commonly confused with syphilis and how can it be told apart?

Answer 37

Haemophilus ducreyi, an STI of developing countries Produces a chancroid: soft-edged, and very painful vs syphilis = chancre: hard, raised edge. not painful.

Question 38

What is the most common curable STD?

Answer 38

Trichomonas vaginalis, with only 30% having symptoms

Question 39

What is the morphology of Trichomonas? Where does it grow?

Answer 39

Flagellated protozoa. Highly motile with no cyst form, can survive on moist surfaces for 1-2 hours. Inhabits vagina in women and urethra / prostate in men

Question 40

Is it possible to get Trich non-sexually, and what does it eat?

Answer 40

Yes, but it's rare It eats lactobacillus normal flora

Question 41

What is the major exam finding with Trich?

Answer 41

Strawberry cervix - colpitis macularis. Inflamed cervix and vagina, with punctate hemorrhagic spots

Question 42

Are men or women more likely to be symptomatic in Trich?

Answer 42

Men are generally asymptomatic Half of women exhibit symptoms in 5-28 days, with vaginal itching / burning, foamy / bad-smelling yellow-green discharge.

Question 43

What is vaginitis vs vaginosis?

Answer 43

Vaginitis - inflammation of vagina caused by infection | Vaginosis - bacterial overgrowth due to altered balance of bacteria in the vagina, not considered an STI

Question 44

What is the major cause of bacterial vaginosis?

Answer 44

Gardnerella vaginalis - a gram-variable coccobacillus. Often grows anaerobically in normal flora, but disruption can lead to a similar discharge as trich (frothy gray or yellow-green)

Question 45

What is the most common fungal vaginosis? What can cause it?

Answer 45

Candida albicans - compromised cell-mediated immunity + pregnancy, diabetes, oral contraceptives use, and antibiotics

Question 46

What is the consistency of fungal vaginosis in a yeast infection?

Answer 46

"cottage-cheese", with accompanying burning / itching of genitals

Question 47

who always do me a heppi

Answer 47

da memo