Flashcards in FunMed PBL: Sexual Health Deck (45)
What is azithromycin?
A macrolide antibiotic derived from erythromycin that is effective against a wide range of gram-positive, gram-negative and anaerobic bacteria
Describe the mechanism of action of azithromycin
Prevents bacteria from growing by interfering with their protein synthesis. It binds to the 50S subunit of the bacterial ribosome, thus inhibiting translation of mRNA.
Explain how the combined pill works to prevent pregnancy
Oestrogen (EE2) - inhibits FSH secretion --> prevents ovulation
Progestogon - inhibits LH secretion --> no ovulation, changes in cervical mucus, reduces tube motility, shrinks the endometrium and alters uterine receptivity
What are absolute contraindications of the combined pill?
IHD, thrombosis, stroke, hyperlipidaemia, liver disease, pregnancy, oestrogen-dependent tumours
What are relative contraindications of the combined pill?
Risk of arterial disease, gall stones, smoking, being over 35, obesity, varicose veins, migraine without aura
What are the advantages of the combined pill?
> If used effectively, nearly 100% effective
> Lower incidence of benign breast lumps, functional ovarian cysts and endometriosis
> Protection from ovarian and endometrial cancer (due to decreased number of ovulation and atrophy of endometrium)
What are the disadvantages of the combined pill?
> Venous affect can cause thrombo-embolitic events due to effect on clotting related to oestrogen
> Arterial affect e.g. Myocardial infarction, due to progestogen affect
> Small increased risk of breast cancer
> Impairs liver function
> Minor side effects e.g. Weight gain, N&V, breast enlargement
Why may someone take the progestogen-only pill?
If they can't have oestrogen due to contraindications such as hypertension, lactation or diabetes
Explain how the progestogen-only pill works to prevent pregnancy
Supresses ovulation in some cycles (15-40%), alters cervical mucus, induces endometrial atrophy and can affect tubal motility
What are the advantages of the progestogen-only pill?
Can be used by those who can’t use COCP, doesn’t increase risk of venous thrombosis or CVD
What are the disadvantages of the progestogen-only pill?
Side effects: Irregular bleeding, headache, breast pain, nausea
What can be tested for at a sexual health clinic?
• Chlamydia (swab)
• Gonorrhoea (swab)
• Herpes (swab) – only if have genital sores
• Syphilis (blood test)
• HIV (blood test)
What is the most common method of HIV transmission, why?
Anal sex with someone who is HIV+; this is due to the thinness of the skin in this area
What ways can HIV be transmitted?
Needlestick, anal sex with affected individual, sharing needles, from mother to baby (before or after birth or during breastfeeding), sharing sex toys, blood transfusions, vaginal sex
Which body fluids contain enough fluid to infect someone?
Blood, semen, vaginal fluids (including menstruation) and breast milk
What are the 4 main ways that the HIV virus enters the bloodstream?
•by injecting into the bloodstream (contaminated needle)
•through the thin lining on or inside the anus and genitals
•through the thin lining of the mouth and eyes
•via cuts and sores in the skin
What are the symptoms of a HIV infection?
Most individuals who are infected experience a short, flu-like illness that occurs 2-6 weeks after infection and lasts 1-2 weeks generally, thereafter there are no symptoms for several years. This is known as a seroconversion illness
What is a virus?
A package of genetic information protected by a protein shell for delivery into a host cell to be expressed and replicated
What is a capsid?
The protein shell of a virus
What is a capsomere?
One of the individual protein units that make up the outer coat capsid of a virus
The complete set of genes or genetic material present in a cell or organism
What is a nucleocapsid?
The capsid of a virus with the enclosed nucleic acid
Describe the mechanism of HIV infection
Interaction between gp120 (glycoprotein on HIV) and CD4 receptor --> gp120 conformational change --> secondary interaction with CCR5 receptor (adhered to membrane) --> gp41 distal tips insert into cellular membrane --> pulls viral and celluar membranes together --> fusion --> contents of HIV injected into CD4+ cell (T helper) --> single strand RNA --> double strand RNA (reverse transcriptase) --> new DNA inserted into host cell genome (integrase) --> viral DNA translated into viral proteins (protease cleaves these) --> viral RNA produced and combines with viral proteins --> new virion --> buds off cell to transmit virus further
How is HIV diagnosed?
Checks for HIV antibodies in the blood, urine, or mouth fluids and this can take up to 3 months to show in an individual after infection
What follow-up/confirmatory tests are conducted in HIV?
Antibody differentiation test which distinguishes HIV-1 from HIV-2 strains, HIV-1 nucleic acid test which looks directly for HIV, antibody tests for anti-HIV antibodies
How is HIV treated?
Aim is to reduce viral load as much as possible with highly active antiretroviral therapy which involves a combination of antiretrovirals being prescribed to top the virus from replicating in the body and allow the immune system to repair itself and prevent further damage. Combination of ARVs are required because HIV can quickly adapt and become resistant
What changes may a HIV positive diagnosis incur in someone's life?
Unable to donate blood or organs, unable to join the armed forces, difficulty in getting life insurance, some countries you can't visit
Explain the mechanism of action of antivirals?
Targets and inhibits: reverse transcriptase, integrate, protease, fusion and entry mediators
What does reverse transcriptase do in HIV infection?
Converts RNA to DNA
What does protease do in HIV infection?
Cleaves precursor proteins
What does integrase do in HIV infection?
Integrates viral DNA into host cell genome
In what situations is the risk of HIV transmission considered low enough for a couple to try and conceive with unprotected sex?
HIV positive partner is taking HAART appropriately, had undetectable viral load for more than 6 months, no STIs, only have unprotected sex when ovulating, pre-exposure prophylaxis for HIV-negative partner too
How may sperm-washing be used to help in conception with someone with HIV?
If HIV-positive male wishes to conceive with HIV-negative woman, this technique is used to separate the seminal fluid (contains HIV) from the sperm (don't contain HIV) which can thereafter be used in a range of fertility treatments
How may self-insemination be used to help in conception with a HIV-positive female?
Partner ejaculates into container, wait 30 minutes for semen to become more liquid, use syringe to collect semen, slowly insert syringe as far into the vagina as possible (aim for cervix) and squeeze out the contents and remain lying down for the next 30 minutes
What should you do if you become pregnant and you have HIV?
Contact HIV clinic because some anti-HIV medicine can harm babies and additional medicines may be needed to prevent the baby getting HIV
Without treatment, what is the chance that someone with HIV will give birth to a baby with HIV?
If you have HIV do you have to disclose this information?
There's no legal obligation to tell employer unless in a frontline job in the armed forces or work in healthcare performing invasive procedures and employer's have restrictions on the health questions they can ask during a job application process due to Equality Act 2010
What is the cause of chlamydia?
Chlamydia trachomatis bacterium is responsible for the infection
How can chlamydia be transmitted?
Can be transmitted during vaginal, anal, or oral sex, and can also be passed from an infected mother to her baby during vaginal childbirth.
What are the symptoms of chlamydia?
50-70% of individuals don’t experience any symptoms at all, but if they are present, they may include:
• pain when urinating
• unusual discharge from the vagina, penis or rectum (back passage)
• in women, pain in the tummy, bleeding during or after sex, and bleeding between periods
• in men, pain and swelling in the testicles
How is chlamydia diagnosed?
Using a swab - a small cotton bud is gently wiped over the area that might be infected, such as inside the vagina or inside the anus
Urine sample test
TESTING FOR CHLAMYDIA TRACHOMATIS BACTERIUM
What is the treatment for chlamydia?
Azithromycin or doxycycline
Describe the mechanism of action of doxycycline
A form of tetracycline; inhibits bacterial growth by inhibiting translation. It binds to the 30S ribosomal subunit and prevents the amino-acyl tRNA from binding to the A site of the ribosome
What is the prognosis for chlamydia?
More than 95% of people will be cured if they take their antibiotics correctly