Lecture 11 - Infections Flashcards
Risk factors of STIs
16 -24 yrs old Black Low socioeconomic background Increased number of sexual partners Gay Lack of contraception Lack of vaccinations - HPV and Hep B Early age of first intercourse
Sexually transmitted diseases
Chlamydia
Gonorrhoea
Chlamydia
Organism: chlamydia trachomatis
Virulence factors:
obligate intracellular bacteria
Unique cell wall that inhibits phagolysosome fusion
Symptoms:
Men - asymptomatic, testicular pain, dysuria, prostatitis, epididymititis and may have discharge
Women - asymptomatic, dyspareunia and post coital bleeding
Complications: Pelvic inflammatory disease Conjunctivitis Reactive arthritis Non - gonoccocal urethritis
Investigation:
NAAT of urine sample
Vulvo-vaginal swab
Speculum
Treatment:
Doxycycline - cell wall inhibitor
Pregnant - erythromycin
Gonorrhoea
Pathogen: Neisseria gonorrhoea
Virulence:
Gram negative diplococci - LPS capsule
Unencapsulated
Pilated - adhere to mucosal membranes in the pharynx and rectum
Symptoms:
Men: thick, yellow discharge +/- dysuria
Women: 50% asymptomatic, vaginal discharge, lower abdominal pain
Complications:
Epididymo-orchitis
PID
Disseminated gonorrhoea infection - reactive arthritis
Investigation: Urethral swab Urine sample - microscopy, culture and NAATs Vulvo- vaginal swab Speculum
Treatment:
Combined antibiotic therapy
- Ceftriaxone
- azithromycin
Non gonococcal urethritis
Inflammation of the urethra with associate discharge
STI cause :
- chlamydia trichomatis
- mycoplasma genitalium
- trichomonas vaginalis
Can be pathogen negative so not always STI
Investigation:
Urine sample - microscopy, culture and NAAT
Trichomoniasis
Pathogen: trichomonas vaginalis
Virulence: Protozoa - parasite Flagella - motile Optimal growth - pH 6 Vaginal pH - 4 - increased alkalinity of vagina favours growth (lac of lactic bacilli)
Symptoms: copious, odourless discharge
Men: discharge and dysuria
Women: vaginal discharge and irritation of vulva and vagina
Identification:
swab of discharge
High vaginal swab
Treatment: metronidazole
Candidiasis
Pathogen: Candida albicans (NOT STI)
Virulence:
Yeast - fungi
Apart of normal vaginal flora - opportunistic
Activated in immunocompromised state e.g diabetes and HIV
Favours high oestrogen - COCP
Symptoms: Pruritis White odourless discharge Pain Dyspareunia
Investigation:
High vaginal swab
Microscopy
Treatment: oral or topical azoles
Bacterial vaginosis
Pathogen: Gardnerella vaginalis (NOT STI)
Pathophysiology:
Lactobacilli is protective against infection due to decreased pH
If the flora is altered - excessive washing or antibiotics can cause bacterial proliferation
Complications:
PID
Symptoms:
Offensive smell and white discharge - patients may wash more and worsen condition
Investigation:
High vaginal swab
KOH - fishy smell
Treatment: metronidazole
Human papillomavirus (HPV)
Virulence:
DNA virus - non enveloped
Strains 6 and 11 - 90% of genital infections
Strains 16 and 18 - cervical cancer
Investigations:
Biopsy
Swab
PCR
Vaccinations - men and women to reduce spread
Gardasil - 6, 11, 16, 18
Cervarix - 16 and 18
Effects:
Anogenital or cutaneous warts - penis, vulva, vagina, cervix and perianal skin
Herpes simplex virus
HSV -1 - oral and genital herpes - cold sores
HSV -2 - genital herpes and recurrent infection - more likely to get HIV
Virulence: DNA virus - enveloped
Lifelong infection - recurrent
Complication:
Dangers in pregnancy - baby can develop herpes via birth canal
Symptoms: Initially asymptomatic Present with painful blisters or ulcers Systemic symptoms: fever, malaise Painful ulcers Discharge Asymptomatic
Investigations:
Check genitals, mouth and anus
Swabs - PCR and NAATs
Management:
Acyclovir - viral replication DNA polymerase inhibitor
Does not eradicate - reduces severity and current episodes
Syphillis
Pathogen: treponema pallidum (bacteria)
Virulence: spirochette
Transmission:
Direct contact
Vertical transmission
40% coinfected with HIV
- not common
- increased instances with anal sex
Symptoms:
Primary syphillis
- very infectious
- painless ulcers in genitals and sites of sexual contact
Secondary syphilis
- 25% untreated cases
- 4 - 10 weeks after initial infection
- multi system - kidneys and rash
Tertiary syphilis
- can be latent
- reactivates later in life when immunocompromised or pregnant
Investigations:
- microscopy
- PCR
- serology
Management:
Penicillin based antibiotics
Management of STIs
Screen for other STIs - co- infection is common
Screen others - contact tracing - similar route of infection
Education
- barrier contraception
- safe sex
- avoid sex until course of treatment is completed
- vaginal hygiene
Pelvic inflammatory disease
Ascending infection from the vagina through the endocervix causing inflammation of female reproductive tract:
- uterus - endometritis
- Fallopian tubes - salpingitis
- ovaries
Causes of PID
Chlamydia trachomatis
Neisseria Gonorrhoea
Gardenella vaginalis
Mycoplasma genitalium - can’t test for
(Outer polymicrobial)
Other sources:
- intrauterine device
Symptoms and signs of PID
Symptoms:
- abdominal pain
- purulent discharge
- dyspareunia
- abnormal uterine bleeding
Signs
- Pyrexia
- abdominal pain on palpation - abdomen and bimanual vaginal exam
- discharge on speculum
