L40 STI's

Question 1

What is the most common STI?

Answer 1

In the UK Chlamydia is the most common STI, in the US, Herpes is the most common STI.

Other common STIs included:

- Chlamydia 
- Gonorrhoea 
- HIV/AIDS 
- Syphilis 
- Genital Herpes 
- Genital Warts 
- Pubic Lice 
- Hepatitis

Question 2

What causes Chlamydia?

Answer 2

It is caused by a gram negative bacteria. There are 3 types - the most common is chlamydia trachomatis which causes genital infection in adults

Question 3

Give an account of Chlamydia:

• How is it screened for?
• What are the symptoms?
• What is the treatment?
• How does it infect?

Answer 3

Chlamydia:

- screened using a genital swab or a urine sample - done currently with the genital swab - can be done in the cervical canal, or from the lower vaginal region
- Life cycle - 2-3 days. Invades the cells and replicates into reticular bodies. After this the cell ruptures and the daughter pathogens invade other cells 
- Symptoms: most are asymptomatic, if symptomatic symptoms are white penile/vaginal discharge. Also leads to pelvic inflammatory disease it is manifested as pain and infertility as chlamydia causes adhesions and damage. It can activate arthritis in patients with arthritis. In infants it can lead to pneumonia or conjunctivitis (blindness) 
- Treatment: antibiotics e.g. azithromycin one day course, erythromycin and doxycycline

Question 4

What causes Gonorrhoea?

Answer 4

It is caused by a gram negative bacteria, diplococcus -

Neisseria Gonorrhoea - second most common in the UK.

Question 5

Give an account of Gonorrhoea:

• How is it screened for?
• What are the symptoms?
• What is the treatment?

Answer 5

Gonorrhoea:

- Diagnosed by genital swabs 
- Most asymptomatic but symptoms can be PID/infertility and urethral/vaginal discharge 
- Treatment: Ceftriaxone injection. There is increasing resistance. Usually given with treatment for chlamydia - so Ceftriaxone and Azithromycin

Question 6

Give an account of HIV:

• How is it screened for?
• What are the symptoms?
• What is the treatment?
• How does it infect?
• What is the treatment in pregnant women?

Answer 6

HIV/AIDs is caused by human immunodeficiency virus - it is Common in MSM, heroin users, haemophiliacs and Haitians.

• Treatment: anti-retroviral HAART - blocks at different points of the cycle e.g. prevents reverse transcription, inhibits binding or inhibiting integrase or blocking the secretion of proteins
• Life long disease - initially the patient will have flu like symptoms
• Pregnant women with HIV, should be given HAART. In general monitor the infection with the viral load. Can low vaginal delivery in a low viral load. The child should not be breast fed.
• HIV binds to the CD4 receptor and gains access to the cell. It is a retrovirus. RNA undergoes reverse transcription mediated by reverse transcriptase. The double stranded DNA integrates into the host cellular DNA through integrase. It may lay dormant in the cell for many years. The virus will replicate and infect other cells.

Question 7

Give an account of Syphillis:

• How is it screened for?
• What are the symptoms?
• What is the treatment?

Answer 7

• If treated at the primary stage there is a 100% cure rate. The test will be positive, as the antibodies are in the body but the individual is not infected. Treatment is with penicillin.
• Bacterial - diagnosed by blood through a blood test. An antibody test.
• Mode of infection is by contract to the ulcer or lesion of the infected person usually by sexual intercourse - in men it accounts for 94% of diagnoses