90 Sexually transmitted infections Flashcards
STI Syndromes
- Genital discharge
- Genital warts
- Genital ulcers
- Sexually transmitted and bloodborne viruses
STIs: “Top 10”
1. Human papilloma virus 2. Chlamydia trachomatis 3. Candida albicans 4. Trichomonas vaginalis 5. Herpes simplex virus 6. Neisseria gonorrhoeae 7. Human immunodeficiency virus 8. Treponema pallidum 9. Hepatitis B 10. Haemophilus ducreyi
What is the main presentation of Human Papilloma Virus?
Genital warts:
• Shaft of penis (male)
• Vagina, vulva, cervix (female)
What is the main presentation of Chlamydia Trachomatis?
Urethritis
What is the main presentation of Candida Albicans?
Vaginal thrush
What is the main presentation of Trichomonas Vaginalis?
- Vagintis
* Lymphogranuloma venereum
What is the main presentation of Herpes Simplex Virus?
Genital herpes
What is the main presentation of Neisseria Gonorrhoeae?
Gonorrhoea
What is the main presentation of Human Immunodeficiency Virus?
AIDS
What is the main presentation of Treponema Pallidum?
Syphilis
What is the main presentation of Hepatitis B?
Hepatitis
What is the main presentation of Haemophilus Ducreyi?
Chancroid
Epidemiology
• Young people: >1/2 of the STIs diagnosed in UK
• 16-24 year-olds have been found to have many more new partners
• Average no. of new heterosexual partners in the previous
5 years was 3.8 (men) and 2.4 (women)
• 1/3 men and 1/5 women reported at least 10 partners in life ‘so far’
• 4.3% of men reported having paid for sex at some time
• 14% of men and 9% of women were currently having ‘affairs’
(concurrent relationships)
• 5.4% of men and 4.9% of women reported homosexual contact
• 12% of men and 11% of women reported heterosexual anal sex in the preceding year
STI Risk Factors
- Young age
- Failure to use barrier contraceptives
- Non-regular sexual relationships
- Homosexuality (MSM)
- Intravenous drug use
- African origin (Sub-Saharan Africa)
- Social deprivation
- Prostitution
- Poor access to advice and treatment of STIs
What individual factos predispose to risky sexual behaviour?
- Low self-esteem
- Lack of skills
- Lack of knowledge of the risks of unsafe sex
What external influences predispose to risky sexual behaviour?
- Peer pressure
* Attitudes and prejudices of society
Which service provisions predispose to risky sexual behaviour?
- Accessibility of sexual health services
* Lack of resources e.g. condoms
Samples and Lab Investigations of STI
- Urethral swab
- Vaginal swab
- Cervical swab
- Ulcer scrape
- Uterine secretions
- Pelvic aspirates
- Urine sample
- Laparoscopy specimens
- Charcoal transport medium for swabs
- Culture for gonococci, yeasts, aerobic + anaerobic bacteria
- Susceptibility testing of microbial cultures
- Culture in cells
- NAATs
- EIAs
- Direct microscopy
- Urine test
HPV mechanism
- Induces hyperplastic epithelial lesions
* Types exhibit tissue/cell specificity
Which HPV types are most important?
HPV types 6, 11, 16, 18 most important of the120 types
Incubation period of HPV
1-6 months
What are the variety of consequences of HPV?
- Cervical carcinoma
- Urogenital warts
- Laryngeal papillomas
- Common, flat and plantar warts
How can HPV virus be identified?
Seen on colposcopy after staining
Treatment of HPV
- Podophyllum
- Cryo
- Laser
- Surgery
What is HPV vaccine based on?
Based on VLP1 (papillomavirus-like particle) a major capsid protein
Name the 2 killed HPV vaccines available
- Cervarix (bivarent)
2. Gardasil (quadrivalent)
What is the current administration plan for HPV (group - age)?
To girls 12-13yrs before they are sexually active
What does HPV vaccine protect against?
Protection against most cases of cervical cancer
Characteristics of chlamydia trachomatis?
- Obligate
- Intracellular
- Gram negative
What do the following serotypes of chlamydia cause:
• A,B, C
• D-K
• L1, L2, L3
- A, B, C: trachoma
- D-K: genital infection
- L1, L2, L3: lymphogranuloma venereum, cancer
What is trachoma?
A contagious bacterial infection of the eye, causing inflamed granulation on the inner surface of the lids
Asymptomatic infection is common in chlamydia. What % in men and women?
- 50% men infected
* 80% women infected
How are ocular infections of chlamydia acquired in neonates?
During delivery
Female chlamydia symptoms?
- Vaginal / anal discharge
- Post-coital bleeding
- Abdominal tenderness
- Pelvic tenderness
- Infertility
- Reiter’s syndrome (arthritis, cervicitis, urethritis + conjunctivitis)
- Proctitis
- Pharyngitis
- Perihepatitis – upper abdominal pain
Male chlamydia symptoms?
- Urethral / anal discharge
- Epididymal tenderness
- Prostatitis
- Reiter’s syndrome (arthritis, urethritis + conjunctivitis)
- Proctitis
- Pharyngitis
- Perihepatitis – upper abdominal pain
What is a NAAT test?
Nucleic Acid Amplification Test (NAAT) is a technique used detect a particular nucleic acid, virus, or bacteria which acts as a pathogen in blood, tissue, urine, etc
What are the investigations available for chlamydia?
- Urine - NAATs
* Endocervical swab - cell culture
Treatment of chlamydia?
• Treat with azithromycin and tetracycline
(doxycycline)
• Azithromycin resistance increasing
What is thrush/ yeast infection?
- Intensely itchy vaginitis
* May present as UTI
What causes thrush/ yeast infection?
Candida albicans
How is thrush/ yeast infection diagnosed?
By microscopy / culture
Treatment of thrush/ yeast infection
Oral fluconozole + topical nystatin
Recurrence and symptomatic rates of thrush/ yeast infection in women vs men
- Recurrence common in women
* Rarely symptomatic in men
What is trichomonas vaginalis?
Anaerobic, single cell, flagellated protozoa
MoA of trichmonas vaginalis?
Attaches to squamous epithelium
Incubation period of trichomonas vaginalis?
4 days - 3 weeks
What structures are infected by trichomonas vaginalis?
Vagina and urethra
What parasite causes trichomoniasis?
Trichomonas vaginalis
Symptomatic infection rates of trichomonas vaginalis in women vs men
- Symptomatic infection common in women
* Uncommon in men
Presentation of trichomonas vaginalis infection?
Yellowish vaginal discharge
Diagnosis of trichomonas vaginalis?
By dark-phase microscopy
Treatment of trichomonas vaginalis infection?
Metronidazole
What are the 2 types of Herpes simplex viruses? What do they affect?
- HSV type 1 (HSV-1) - usually affects the oral region and causes cold sores
- HSV type 2 (HSV-2) – associated with genital infection (penis, anus, vagina)
Transmission of genital herpes?
- Sexual contact
* During birth (30-40% risk)
What can neonatal genital herpes infection result in?
Disseminated infection often involving CNS
Presentation of genital herpes during the primary infection?
• Febrile flu-like prodrome (5-7 days)
• Tingling neuropathic pain in genital area/ buttocks/ legs
• Extensive bilateral crops of painful blisters/ ulcers in the
genital area including the vagina and cervix in women
• Tender lymph nodes (inguinal)
• Local oedema
• Dysuria
• Vaginal or urethral discharge
Treatment of genital herpes primary infection?
Aciclovir
What is the process of genital herpes recurrence?
• Following primary infection, virus becomes latent in local sensory ganglia
• Periodic reactivation which can cause symptomatic lesions or asymptomatic, but still infectious, viral shedding
• Episodes are usually shorter (≤10 days)
• Median recurrence rate after a symptomatic 1st episode:
– HSV-2: approx. 4 attacks in the subsequent 12 months.
– HSV-1: approx. 1 attack in the subsequent 12 months.
• Attacks usually become less frequent over time
Diagnosis of HSV?
• Clinical appearance
• Viral culture
• DNA detection using NAAT of a swab from the base of an ulcer / vesicle fluid
• Serology
- identify those with asymptomatic infection
-distinguish between the2 types of HSV
• May take up to 12 weeks to become antibody +ve after primary infection
Features of neisseria gonorrhoeae infective agent?
- Gram -ve
- Intracellular diplococcus
- Humans only host
- Infects epithelial cells of mucous membrane of GU tract or rectum
- Development of localised infection with production of pus
- Possible asymptomatic carriage in women
Name a bacteria that is gram negative diplococcus
Neisseria gonorrhoeae
Describe the consequences of gonorrhoea (presentation)?
- Acute inflammation and discharge in male patients
- Cervical discharge in female patients
- Rectal infections in male homosexuals
- Oral pharyngitis contracted by oral-genital contact
- Disseminated infection - septic arthritis
Female presentation/symptoms of gonorrhoea?
- Dysuria
- Rectal infection - asymtomatic
- Sapingitis, PID
- Pharyngeal infection
- Post-coital bleeding
- Septic arthritis
Male presentation/symptoms of gonorrhoea?
- Urethral discharge
- Anal discharge, +/- pain and bleeding
- Epididymal tenderness
- Pharyngeal infection
- Septic arthritis
Babies presentation/symptoms of gonorrhoea?
Ophthalmia neonatorum - blindness
What is ophthalmia neonatorum?
How do babies get it?
- Conjunctivitis contracted by newborns during delivery
- Mother infected with Neisseria gonorrhoeae or Chlamydia trachomatis
- Can cause blindness without treatment
Lab diagnosis of gonorrhoea?
- Light microscopy of Gram-stained genital specimens to look for Gram-negative diplococci
- NAAT-can use urine or swabs
- PMN in urethral pus
Treatment of gonorrhoea?
• Treatment for confirmed, uncomplicated gonococcal infection in adults is one of the following (all given as a single dose):
- Ceftriaxone
- Cefixime
- Ciprofloxacin (if beta lactam allergy)
- Increasing resistance to penicillin, tetracycline + ciprofloxacin
- Most strains respond to ceftriaxone
- Doxycyline also given as many patients have concomitant chlamydial infection
- Azithromycin resistance increasing
What drugs is also given in treatment of gonorrhoea to patients with concomitant chlamydial infection?
Doxycline
What drugs is given to treat gonorrhoea if beta lactase allergic?
Ciprofloxacin
Transmission of HIV
- Via blood/ blood products or contaminated needles
- Sexually
- Perinatally
HIV:
• Family
• Genus
• HIV types
- Family - retroviridae
- Genus - lentivirus
- HIV-1 and HIV -2 pathogenic for humans
- HIV-1: most common
- HIV-2: less virulent
HIV viral features
- Spherical (80-100nm)
- Enveloped
- RNA genome
- Retrovirus - uses reverse transcriptase to make DNA copy from viral RNA
HIV progression to AIDS
- Exposure to HIV
- Seroconversion
- Asymptomatic
- Persistent generalised lymphadenopathy
- AIDS-related clinical features
- AIDS
Treatment of HIV infection
- Nucleoside Reverse Transcriptase Inhibitors (NRTIs)
- Non-nucleoside Reverse Transcriptase Inhibitors (NNRTIs)
- Protease Inhibitors (PIs)
What is HAART?
• Highly Active Anti-Retroviral Therapy
• Many possible regimens and combinations • Initial treatment often contain: - 1NRTI + 1 PI OR - 2 NRTIs + 1 NNRTI
Diagnosis of HIV infection
• Diagnosis of HIV-specific antibodies:
- ELISA
- Western Blotting
• NAAT used to detect viral RNA in serum
• Quantitative NAAT used to measure viral load
• Individual testing must be preceded by counselling
• An initial -ve result should always be followed up
Prevention of HIV infection
- Screening of blood products
- Needle exchange programmes
- Anti-retroviral prophylaxis for needlestick injuries
- Avoiding high-risk sexual partners
- Use of barrier contraception
- Elective caesarian section
HBV viral features
- Hepadnavirus
- Double-stranded DNA genome
- Enveloped
HBV antigens
- HBsAg – surface antigen
• Indicates infectivity
• Anti-HBsAg provides immunity + appears late - HBcAg – core antigen
• Appears early in infection - HBeAg – pre-core antigen
• Indicates high transmissibility
HBV transmission
- Blood or blood products
- Contaminated needles and equipment used by IV drug users
- Association with tattooing, body piercing and acupuncture
- Sexual intercourse
- Intra-uterine, peri- and post-natal infection
- Contaminated haemodialysis equipment
HBV stages of infection
• Long incubation period - up to 6 months
• Development of acute hepatitis
• Fulminant disease carries 1-2% mortality rate
• 50% patients develop chronic active hepatitis
– Cirrhosis
– Hepatocellular carcinoma
Difference between HBV acute and chronic infection
- HBV - acute infection (self-limited)
* HBV - chronic infection (persistent)
HBV clinical features
1. Pre-icteric Stage • Malaise • Anorexia • Nausea • Pain in right upper quadrant (tender liver)
2 Icteric Stage
• Jaundice
• Dark urine (bilirubin)
HBV treatment
- Pegylated interferon (peginterferon)
* Antiviral activity of nucleoside analogues (e.g. oral lamivudine) - may be successful even in chronic HBV patients
HBV prevention
- HBsAg vaccine - good protection following 3 injections over 6 month period
- HBV immunoglobulin
- Blood screening
- Needle exchange programmes
- Sexual health education
Infection of treponema pallidum leads to..
Syphilis
What are the three stages of syphilis?
- Primary
• Hard genital or oral ulcer (chancre) at site of infection after ~ 3 weeks
• Asymptomatic for up to 24 weeks - Secondary
• Red maculopapular rash anywhere
plus pale moist papules in urogenital region and mouth (condylomas)
• Latent for 3 – 30 years - Tertiary
• Degeneration of nervous system, aneurysms and granulomatous lesions in liver, skin and bones (gummas) in about 40% of patients
Congenital syphilis
- Placental transfer after 10-15 weeks of pregnancy
- Infection can cause death or spontaneous abortion of foetus
- Survivors develop secondary syphilis symptoms
Diagnosis of syphilis
- From lesions or infected lymph nodes in early syphilis
- Dark field microscopy
- Direct fluorescent antibody (DFA) test
- NAAT
- EIA - can be for immunoglobulin M (IgM) for early infection or immunoglobulin G (IgG - positive at 5 weeks) or both
What is chancroid caused by?
Haemophilus ducreyi
• Gram negative bacterium
What is chancroid characterised by?
Painful, necrotising genital ulcers
What can chancroid be accompanied by?
Inguinal lymphadenopathy
Diagnosis and treatment of chancroid
- Diagnosed by microscopy/ culture
* Treatment with a macrolide (e.g. erythromycin) or ceftriaxone
How to reduce risk of STIs?
- Fewer sexual partners
* Use condoms
