Pathogenesis of HIV and the major Sexually Transmitted Infections

Question 1

Name some common bacteria which cause STI’s in the UK

Answer 1

N. Gonorrhoea
C. Trachomatis
Ureaplasma
Mycoplasma

Question 2

Name some viruses that cause STI’s in the UK

Answer 2

Herpes Simplex Virus
Human Papilloma Virus
Pox Virus

HIV / Hep B (Uncommon)

Question 3

How can infections be transmitted from mother to baby?

Answer 3

• in utero (trans placental)

- peri natal : eye mucous membrane, present in breast milk.

Question 4

What organism is a gram negative coccus (diplococus)?

Answer 4

Neisseria gonorrhoeae

Question 5

What are the 3 cell wall layers of N. Gonorrhoea (a gram negative bac)

Answer 5

1) Outer cytoplasmic membrane (lipo-oligosaccharides)
2) Thin Peptidoglycan cell wall
3) Inner cytoplasmic membrane

Question 6

What are the local complications of N. Gonorrhoea?

Answer 6

• epididymitis, prostatitis
• peritionitis
• fitz-hugh-curtis syndrome

Question 7

What are the metastatic complications of N. Gonorrohoea?

Answer 7

• bacteraemia
• arthritis
• dermatitis

Question 8

What are the effects of Gonorrhoea during pregnancy?

Answer 8

• premature labour

- neonatal conjunctivitis

Question 9

How is N. Gonorrhoea diagnosed?

Answer 9

Microscopy - urethral swab

Culture - endocervical (women), urethral (men)

Nucleic Acid Amplification Test - PCR

Question 10

What are the treatments of N. Gonorrhoea?

Answer 10

• beta Lactams (Benzyl Penicillin, amoxicillin)
• Cephalosporins (cefixime, ceftriaxone)
• Fluoroquinolones (ciprofloaxacin)

Question 11

What is non-gonococcal urethritis?

Answer 11

It is inflammation of the urethra that is not caused by gonorrhea. It can be caused by Chlamydia Trachomatis.

Question 12

What are the symptoms of Chlamydia?

Answer 12

• Urethritis (inflammation of urethra)
• Cervicitis (inflammation of cervix)
• dysuria (painful urination)

Question 13

What are some complications of a Chlamydial Infection?

Answer 13

• Tubal Infertility (ectopic pregnancy)
• Neonatal conjunctivitis
• Infant Pneumonia
• Reiter’s Syndrome (affects men = arthritis, conjunctivitis, urethritis)

Question 14

What is the treatment of Chlamydia?

Answer 14

Azithromycin

Doxycycline

Question 15

What is Pelvic Inflammatory Disease?

Answer 15

inflammation of the female genital tract, accompanied by fever and lower abdominal pain.

Increases risk of infertility

Question 16

What are the organisms which cause Pelvic Inflammatory Disease?

Answer 16

N. Gonorrhoeae
C. Trachomatis
Haemophilius

Question 17

Which types of Human Papilloma virus are associated with genital warts and cancer?

Answer 17

HPV 6 and 11 = warts

HPV 16 and 18 = cancer

Question 18

What is condylomata accuminata? and how is it treated?

Answer 18

Genital warts

Treated:

• burn
• freeze
• cut
• imiquimod (topical cream)

Question 19

What causes Genital Herpes and what are the symptoms?

Answer 19

Cause : Herpes Simplex Virus (double stranded DNA virus)

Symptoms:

• pain, itching
• dysuria (pain on urination)
• vaginal/urethral discharge
• ulcers

Question 20

Why does genital herpes recur and persist?

Answer 20

The virus infects sensory neuron cells and spreads to the sacral nerve ganglia where it is latent (dormant).

Question 21

What is the treatment of Genital Herpes?

Answer 21

Acyclovir

Question 22

What are the complications of genital herpes?

Answer 22

• dissemination (spreads)
• meningitis
• encephalitis
• urinary retention
• sacral nerve parasthesiae (abnormal sensation)

Question 23

What causes Syphilis?

Answer 23

Treponema Pallidum (Spirochaete - double membrane bacteria)

Question 24

How does Syphilis spread?

Answer 24

Via lymphatics and blood stream within days

Question 25

What is the average incubation period of syphilis?

Answer 25

21 days

Question 26

How does syphilis present in the 2nd stage?

Answer 26

Skin: - Rash - Condylomata Lata (warty erosions) CNS: headache Overall: fever, malaise, weight loss

Question 27

How does syphilis present in the 3rd stage?

Answer 27

Neurosyphilis; - meingovascular - personality change - don't react to light ect. Cardiovascular: Aortitis

Question 28

What is the treatment of Syphilis?

Answer 28

Penicillin

Question 29

What infection causes Jarish - Herxheimer reaction?

Answer 29

Syphilis causes Jarish Herxheimer reaction.

Question 30

What is Trichomoniasis and what causes it?

Answer 30

It is an STI that is caused by the parasite - Trichomonas Vaginalis. It presents with: - Green, thick Vaginal discharge - inflammation around vagina - dysuria (pain when passing urine)

Question 31

What is Bacterial (anaerobic) vaginosis? (cause and presentation)

Answer 31

It is a vaginal infection caused by anaerobic bacteria and Gardenella Vaginitis. It causes water discharge with a fishy odour.

Question 32

How is Bacterial Vaginosis treated?

Answer 32

-Metronidazole

Question 33

What are the factors that cause Candidiasis (thrush / balanitis) infection?

Answer 33

- oral contraceptives - antibiotics (inhibit normal flora) - poorly controlled diabetes

Question 34

What are the symptoms and signs of Candidiasis?

Answer 34

Vulval, vaginal, penile itching / irritation thick discharge / white plaques.

Question 35

What Is the treatment for candida albicans?

Answer 35

Fluconazole | or topical cream

Question 36

What is HIV?

Answer 36

HIV is a retrovirus that has a high rate of mutability. It attacks the immune system,

Question 37

How doe HIV enter the host cell and affect the immune system?

Answer 37

The virus interacts to the CD4 receptor and the CC5R chemokine receptor to gin access to the cell. In the cytoplasm, revers transcriptase occurs. the dsDNA is the imported into the nucleus and incorporated into the cell genome. This causes the loss of CD4+ve T cells. So normally non pathogenic organisms can cause infection.

Question 38

What are the symptoms of a primary HIV infection?

Answer 38

- fever - pharyngitis - lymphadenopathy - rash

Question 39

How is HIV diagnosed ?

Answer 39

- antibody testing - PCR - CD4 cell count