STI Flashcards
STI Risk Groups
Men who have sex with men (MSM)
Sexually active gay, bisexual and other men
Not using condoms
Anal sex increases risk: “riskiest sexual behaviour” for exposure to HIV.
Apps- Online
Commercial Sex Workers (CSW) and their clients
Multiple Partners who they don’t know the sexual history of
Unprotected Oral Sex- transmission route for most STIs.
People from countries with higher rates of STIs
High-risk regions include: Sub-Saharan Africa South-East Asia Latin America/Caribbean
People with multiple partners, or partners from other high risk group
Increases the risk of STIs being passed on quickly.
Consequences of Infection
Women
Infertility
Pelvic Inflammatory Disease
Cervical Cancer
Adverse pregnancy outcomes
Men
Infertility
Narrowing of the Urethra
Infants
Eye Infections
Blindness
Death
What are the main groups of sexually Transmitted Infections
viral diseases
bacterial diseases
parasitic
Chlamydia
Chlamydia: Silent epidemic
Pathogen - Chlamydia trachomatis
Gram Negative
Pelvic Inflammatory Disease, Eye Infections, urethritis
nonmotile coccoid bacteria that are obligate intracellular parasites of eukaryotic cells.
Can be grown in tissue culture
Reticular body
Elementary body – infectious form of mucosal cells
Chlamydia Symptoms
MEN
Urethritis
Proctitis
Epididymitis
WOMEN
Urethritis
Endocervicitis
Proctitis
PID
Perihepatitis
Chlamydia Diagnosis & Treatment
Diagnosis-
What is the specimen site??
Clinical examination
Urine test- 1-2 hours after last expulsion
Bacterial Culture
Nucleic acid probes – PCR
Treatment
Patient and partner(s) should be treated
Doxycycline
Erythromycin
AZITHROMYCIN (first choice)-however some bacteria are becoming resistant therefore we use a combination of antibiotics
Neisseria gonorrhoea
Pathogen – Neisseria gonorrhoea
Gram-negative diplococcus
SYMPTOMLESS – then severe
Can be cultured in selective media
Sexual contact
Perinatal
Less common than Chlamydia
Prevalence varies with population
Can also get infections of the throat, rectum, eyes and conjunctiva.
Gonorrhoea: signs and symptoms??
Can be disseminated around the body:
Arthritis
Dermatitis
Pericarditis and endocarditis
Meningitis- affect lining of brain
Infections in testicles
PID
Gonorrhoea Diagnosis & Treatment
Diagnosis
Clinical examination
Men- urine, urethra
Women- Vagina or Cervix
Gram stain
Culture
Nucleic acid probes
Treatment
Patient and partner(s)should be treated
Drugs of choice
Ceftriaxone – 125 mg i.m.
Azithromycin
Unfortunately antibiotic resistance is increasing
“Super” Gonorrhoea
1st ever case of Super gonorrhoea in the UK March 2018
Patient: unprotected sex in South East Asia
Infection failed to respond to 1st line antibiotics
Ceftriaxone and azithromycin
Patient treated with ertapenem- after trial and error
MDR Gonorrhoea prevalent in countries with sex tourism
Where antibiotics can be purchased easily
Infection has moved onto Australia
Syphilis
Pathogen: Treponema pallidum
Spiral shaped, tend to be Gram negative
Grows in cell co-cultures at low oxygen concentrations in brewer’s jar
Sexual contact
Can stay in the body without symptoms
Increase in syphilis cases in MSM
a large significant difference between men and women with a lot more cases affecting in men
Syphilis Infection
Primary
Secondary
Latent (early and late)
Tertiary (late)
Late stage Clinical Manifestation
Destructive gummas (growth) in skin, bones and organs
Aortic valve injury
CNS manifestations
Dementia
Syphilis during pregnancy
Foetal death
Growth restriction
Multiple anomalies
Immediately apparent at birth
Delayed appearance
Diagnosis and Treatment
Diagnosis
Clinical examination
Serology – mainstay of diagnosis (antibodies to detect)
VDRL (venereal disease research laboratory)
RPR (rapid plasma reagin) – screening test
MHA (Microhemagglutination) (blood cells are used they have antigen if there is a reaction like clotting there serum is positive for syphilis)
FTA fluorescent treponemal antibody absorption using entire lysed bacterial cells
Treatment
Patient and sexual partner(s) should be treated
Antibiotic therapy
Penicillin – preferred in pregnancy
Doxycycline
Tetracycline
Bacterial STI’s
Chlamydia, gonorrhoea and syphilis
Viral STI’s
Herpes
Herpes Simplex Virus
Genital Herpes!
alphaherpesvirus subfamily of herpesviruses
dsDNA enveloped virus, genome of ~150 kb
HSV-1 and HSV-2 share 50 - 70% genetic homology
antigenic cross-reaction with VZV (chickenpox)
Genital lesions may be primary or recurrent
Herpes Simplex Virus Symptoms
Pain, itching, scarring, scabs, open sores
Red bumps, tiny white bumps/ulcers/blisters, take weeks to heal
Dangerous in premature infants
Dissemination; where the brain is involved, the prognosis is severe.
Residual disabilities.
Treated with Acyclovir=antiviral
Prevention is to offer Caesarean
Human Papilloma Virus (HPV)
Causes Genital Warts, often symptomless
Papillomavirus family
dsDNA virus, genome of ~150 kb
Genital warts and laryngeal papilloma
HPV Vaccines prevention, safe sex
Can cause cancer (oncogenic)
Cervical Cancer screening
Human Papilloma Virus Vaccine
Gardasil 9
90% Efficacy!
Vaccine can eliminate disease
Fewer Cervical Smears
HPV Symptoms & Treatment
HPV can affect the mouth, throat or genital area
Penetrative sex is not essential
Transmission routes:
any skin-to-skin contact of the genital area
vaginal, anal or oral sex
sharing sex toys
Diagnosis:
Cervical Smear
If HPV is linked to cancer (abnormal changes) then appropriate cancer diagnosis and treatment routes are established.
Cancer types include:
Cervical cancer
Anal cancer
Penile cancer
Vulval Cancer
Vaginal Cancer
HIV/AIDs
Acquired Immune Deficiency Syndrome
Death usually results from an opportunistic Infection
HIV discovered in 1984 by Luc Montagneir
In 2019, a total of 98,552 people (30,388 females and 68,088 males) were seen for HIV care in the UK
HIV is transmitted via Four body fluids
- Blood (needles, contact blood-blood)
- Semen (sex- high risk sex)
- Vaginal Secretions (Sex, birth- mother to child)
- Breast Milk (mother to child)
HIV/AIDs: Diagnosis and Treatment
Diagnosis
Enzyme Linked Immunosorbent Assay tests for HIV Antibodies
If ELISA is positive, same sample is tested again
If ELISA is positive again, then a Western Blot Test is done (proteins for virus are detected highly specific).
Western Blot - test for Viral antigens
Prophylaxis- PreP -preexposure prophylaxis
Treatment
AZT: azidothymidine (inhibits viral RT, analogue of dGTP)
3TC ( 2’-deoxy-3’-thiacytidine – cytosine analogue)
Protease Inhibitor (HIV-1 protease essential for virulence)
Parasitic STI’s
Phthirus pubis
Found in underarm and leg hair
hair on the chest, abdomen and back
facial hair, such as beards and moustaches
eyelashes and eyebrows (very occasionally)
Biology
Adults are small (2mm). Yellow-grey/red
6 legs
Look like small crab- hold onto hair base
Eggs laid in sac that sticks onto hair
Visible in hair
Phthirus pubis
Sexually transmitted
Bodily contact
Condoms do not prevent this!
Treatment
Treated at home
Insecticidal creams, lotions, shampoos
3-7 days
Lice can become resistant
To prevent re-infection all sexual partners should be treated
Trichomonas vaginalis
Trichomoniasis
Common in women
Lower genital tract infection
70% cases are Symptomless
Diagnosis
-Symptoms
-Antigen tests
-PCR
Complications
-Perinatal
-Co-occurrence with other STIs
Trichomonas vaginalis
Symptoms in Men
Itching or irritation inside the penis;
Burning after urination or ejaculation;
Discharge from the penis.
Symptoms in Women
Itching, burning, redness or soreness of the genitals;
Discomfort with urination;
A change in their vaginal discharge -unusual fishy smell.
Metronidazole
STI Prevention
Safe Sex
Abstinence: The only sure way to prevent contracting an STI is not to have oral, anal or vaginal sexual contact.
Condoms -only protect the skin they cover, any sores/warts found on the genital region not covered by the condom can still spread to another person’s skin.
Get tested and have regular check ups
Kits!
