unit 4 - stis

Describe the agglutination test for diagnosis of syphilis

test uses gelatin/RBCs that are sensitized to T. pallidum bacterium, mixes with patient blood serum/plasma

—> if blood has t. pallidum antibodies, they will bind to particles (agglutination) (+)

—> if no antibodies in the blood, the two substances will not bind (-)

Describe the ICA for trichomoniasis

• sample of vagina/cervix/urethra/urine is with buffer and mixed

• test stick is inserted and read (NAAT/PCR)

  • + is two lines

  • - is 1 line

Chlamydia trachomatis

characteristics (incl. Gram morphology): gram (-) bacteria, obligate intracellular pathogen, difficult to culture in lab

disease(s): chlamydia, pelvic inflammatory disease, trachoma, nongonococcal urethritis (NGU), lymphogranuloma venereum (LGV)

transmission: sexual, hand to eye contact

diagnosis: NAAT

treatment: antibiotics

prevention: safe sex

Neisseria gonorrhoeae

characteristics (incl. Gram morphology): gram (-) diplococcus, highly fastidious, challenging culture in lab

disease(s): gonorrhea, pelvic inflammatory disease, neonatal gonorrhea

transmission: sexual contact, vertical

diagnosis: NAAT

treatment: antimicrobial resistant strains are too common

virulence factors: adhesins (type iv pili, biofilm formation)

prevention: safe sex, prophylactic erythromycin

Treponema pallidum

characteristics (incl. Gram morphology): gram (-) spirochete, not easily cultured

disease(s): syphilis, congenital syphilis

transmission: sexual contact, vertical (transplacental)

diagnosis: serology (TPPA)

treatment: antibiotics

virulence factors: adhesins, motility

Trichomonas vaginalis

characteristics (incl. Gram morphology): motile flagellated protozoa

disease(s): trichomoniasis

transmission: sexual contact

diagnosis: ICA, NAAT

treatment: antiobiotic

prevention: condoms

Explain the attachment of HIV to a host cell

virus circulates through blood

• targets t helper cells and infects new ones

• immune system rendered too ineffective to fight off infections/cancers

Describe the stages of HIV infection and effects of HIV infection on the immune system

1) acute

• The virus replicates rapidly and spreads throughout the body

• Causes a flu-like illness with symptoms like fever, swollen glands, fatigue, and rash

• The viral load is very high, making the risk of transmission high

• The CD4 count drops significantly before rebounding to a stable level

2) chronic infection

• The virus continues to reproduce, but at very low levels

• People in this stage may have no symptoms and can feel healthy for many years

• Without treatment, the immune system is still being damaged, and the CD4 cell count gradually decreases

• This stage can last for about 10 years or longer

3) AIDS

• This is the most severe stage of HIV infection

• It occurs when the CD4 cell count drops below 200 cells per cubic millimeter of blood, or when a person develops an opportunistic illness

• The immune system is so badly damaged that it can no longer fight off infections and cancers

• Without treatment, people with AIDS typically survive for about three years

List the current methods of preventing and treating HIV infection

Treatment:

• ART (antiretroviral therapies)

Prevention:

• condoms

• PrEP (pre-exposure prophylaxis)

• PEP (post-exposure prophylaxis)

Identify 7 pathogens that cause AIDS-defining illnesses in people who are HIV+

1) candida albicans

2) cryptococcus neoformans

3) histoplasma capsulatum 

4) pneumocystis jirovecii

5) cryptosporidium spp.

6) toxoplasma gondii

7) mycobacterium spp.

Herpes Simplex Virus 2 (HSV-2)

characteristics (RNA/DNA): DNA

disease(s): genital/neonatal herpes, meningitis

transmission: sexual contact (even if lesions are absent), vertical transmission

diagnosis: NAAT/PCR

treatment:Acyclovir (guanine analog, will not cure latent infections)

vaccine (if available): none

prevention: protected sex (lowers risk) 

Human papilloma virus (HPV)

characteristics (RNA/DNA): DNA

disease(s): common/plantar/genital warts, linked to cervical/penile/anal/throat cancers

transmission: direct (common warts), sexual (genital)

diagnosis:

• clinical presentation (warts)

• NAAT/PCR (cervical infection)

treatment:

• warts: self-resolve/cryotherapy

• cervical infection: self-resolving

vaccines: Gardasil 9 (subunit) 

prevention: pap smear screening 

Human immunodeficiency virus (HIV)

characteristics (RNA/DNA):
* Retrovirus

RNA genome

reverse transcriptase (RT)

disease(s): hiv and aids

transmission:

• transfer of bodily fluids

• vertical transmission

diagnosis:

• ELISA screening (antibodies)

• NAAT (for determining viral antigen + load)

treatment: RT inhibitors, protease inhibitors

prevention/management:

• Safe sex

• PrEP

• PEP