Microbiology - STIs Flashcards
What are some common presentations of man with an STI?
- Asymptomatic
- Urethral discharge
- Dyrsuria
- Scrotal pain/swelling
- Rash/sores
- Systemic Sx
What are some common presentation of a woman with an STI?
- Asymptomatic
- Vaginal discharge (+/- urethral, rectal)
- Ulceration (painful/painless)
- Itching/soreness (lumps/growths)
- Abnormal bleeding (IMB, PCB)
- Abdo pain, dyspareunia, dyrsuria
- Systemic Sx
What are some common causes of discharge?
- Gonorrhoea
- Chlamydia
- Trichomonas
- Candida
- Bacterial Vaginosis
What are some common causes of ulceration?
- Syphilis (Painful)
- HSV (painless)
- LGV
- Chancroid
- Donovanosis
What are some common causes of rashes, lumps/growths?
- Genital warts: HPV
- Molluscum contagiosum
- Scabies
- Pubic lice
What is the causative organism of gonorrhoea?
Neisseria gonorrhoeae
- Obligate intracellular gram -ve diplococci
What are some common presentations of an uncomplicated gonorrhoeal infection (90%) in a man?
Gonococcal urethritis:
- Most common STI in europe
- Mucoid/mucopurulent discharge
Post-gonococcal urethritis:
- Following gonorrhoeal Tx
- Prevented by concomitant Tx with tertrcycline
Rectal prostitis:
- Mainly in MSM
What is the most common presentation of an uncomplicated gonorrhoeal infection (90%) in a woman?
Mucopurulent cervicits:
- Erythema + oedema
- Urethra (vaginal leakage)
What is a common presentation of a complicated gonorrhoeal infection (10%) in a man?
Prostatitis
What is a common presentation of a complicated gonorrhoeal infection (10%) in a woman?
PID (salpingitis)
- Ascending infection
What is Opthalmia neonatorum?
Neonatal conjunctivitis
- Develops if left untreated when transfer to child from birth canal
- Presents in 1/2 days with Gonorrhoea
- Presents in 1-2wks with Chlamydia
What is the gold standard investigation for diagnosing gonorrhoea?
Urethral (Sens: 95%) / Rectal (Sens: 20%) smears
- Produces a culture
What is the treatment for gonorrhoea?
IM Ceftriaxone (250mg) Single Dose
What is the causativ organism for chlamydia?
Chlamydia trachomatis
- Obligate intracellular gram -ve pathogen
- Can’t be cultured on agar
What is the epidemiology of chlamydia?
- Common in young adults
- 10% <25yrs infected in UK (Most common)
- Asymptomatic (50% men, 80% women)
How is chlamydia classified?
- Serovars A, B, C: Trachoma (infection of eyes which can cause blindness)
- Serovars D-K: Genital chlamydia, opthalmia neonatorum
How is chlamydia diagnosed?
NAAT (nucleic acid amplification test) from genital swabs
What is the treatment for chlamydia?
- Azithromycin 1g Stat
OR - Doxycycline 100mg BD (7/7)
What are some complications of Chlamydia?
- PID (tubal factor infertility, ectopic pregnancy, chronic pelvic pain)
- Epididymitis
- Reiter’s Syndrome
- Adult conjunctivitis, opthalmia neonatorum
What is Lympho-granuloma venerum and its epidemiology?
- Lymphatic infection with Chlamydia trachomatis: Serovars L1-3
- Endemic in parts of developing world
- MSM in developing world
What are some symptoms of Lympho-granuloma venerum?
Early LGV (primary stage):
- 3-12 days
- Painless genital ulcer
- Proctitis
- Balanitis
- Cervicitis
Early LGV (secondary stage):
- 2wks-6mths
- Painful inguinal buboes
- Fever
- Malaise
- Rare: hepatitis, meningo-encephalitis, pneumonitis
Late LGV:
- INGUINAL LYMPHADENOPATHY
- GENITAL ELEPHANTIASIS
- Genital + perianal ulcers/abscesses
- Frozen pelvis
Current LGV outbreak:
- Rectal Sx/proctitis (pain, tenesmus, bleeding)
How is lympho-granuloma venerum diagnosed?
- NAAT
- Genotypic identification of L1-3 Serovar
What is the treatment for lympho-granuloma venerum?
Doxycycline 100mg BD for 3wks
What is the causative organism of syphilis?
Treponema pallidum
- Obligate gram -ve spirochaete
What are the symptoms of primary syphilis?
Macule to papule to PAINLESS SOLITARY GENITAL ULCER
- Appears 1-12wks folloeing transmission
- May persist 4-6wks
Regional adenopathy
What are the symptoms of secondary syphilis?
- Systemic bacteraemia 1-6mths after infection (fever, malaise, lymphadenopathy)
- MACULOPAPULAR RASH ON PALMS + SOLES (+ back, trunk, limbs)
- Condyloma acuminate (genital warts)
- Mucosal lesions
- Uveitis
- Neurological involvement
What are the symptoms of latent syphilis?
- No obvious signs
- Serological infection
- Asymptomatic
What are the symptoms of tertiary syphilis?
2-30yrs later
GUMMATOUS:
- Skin/bone/mucosa granulomas
- Spirochaetes scanty
CARDIOVASCULAR:
- Mimics any cardiac disease
- Especially: Aortic Root Dilatation/Aortitis
- +++ Spirochaetes
- +++ Inflammation
NEUROSYPHILIS:
- Dementia
- Tabes dorsalis
- Argyll-Robertson pupil
- Spirochaetes in CSF
How is syphilis diagnosed?
- DARK GROUND MICROSCOPY: Treponemes seen in primary lesions
- Ab tests (Treponemal + non-treponemal)
How does a non-treponemal test work for syphilis detection?
- Detects Abs against non-specific antigen
- VDRL Slide test: detects lipoidal Ab on host + treponemal cells
- Can get false +ves (need to confirm with treponemal test)
- RPR = modified VDRL test
- Useful in primary syphilis
- Titre falls in response to treatment (4-fold reduction suggestst response to Tx)
How does a treponemal test work for syphilis detection?
- Detects Abs against specific antigens from T. pallidum
- More specific than non-treponemal test
- Remains positive for years (despite effective Tx)
What are some examples of treponemal tests for syphilis?
- Enzyme Immunoassay (EIA)
- Fluorescent Treponemal Antibody (FTA)
- T. pallidum Haemagglutination Test (TPHA)
- T. pallidum Particle Agglutination Test (TP-PA)
What is the treatment for syphilis?
Single Dose IM Benzathine Penicillin
- Doxycycline if allergic
What is Jarisch-Herxheimer Reaction, its symptoms and treatment?
Common reaction to Abx given for syphilis Tx
- Develops within hours of Abx
- Clears within 24hrs
Sx:
- Flu-like Sx
- ?Exacerbation of syphilitic Sx
Tx:
- Paracetamol/analgesia
What is congenital syphilis and its symptoms?
Syphilis occuring during pregnancy/birth
- Develops over first couple years
Sx:
- Hepatosplenomegaly
- Rash
- Fever
- Neurosyphilis
- Pneumonitis
Late congenital syphilis can occur in 40%
What is the causative organism for Chancroid?
Haemophilus ducreyi
- Gram -ve coccobacillus (like Hib)
What are the features of Chancroid?
- Tropical ulcer disease
- Mainly in Africa (rare in UK)
- Multiple painless ulcers +/- lymphadenopathy
How is Chancroid diagnsed?
- Culture: CHOCOLATE AGAR
- PCR
What is the causative organism for Donovanosis (granuloma inguinale)?
Klebsiella granulomatis
- Gram -ve bacillus
What are the feature of Donovanosis (granuloma inguinale)?
- Present in tropical regions (Africa, India, PNG, Australian aboriginal communities)
- Large, beefy, painless, red ulcers
How is donovanosis diagnosed?
- Giemsa stain of biopsy/tissue crush
- DONOVAN BODIES
How is donovanosis treated?
Azithromycin
What are some common enteric pathogens that are spread through oro-anal contact?
- Shigella
- Salmonella
- Giardia (protozoa)
What is the causative organism for Trichomoniasis?
Flagellated protozoan - T. vaginalis
How does Trichomoniasis present in men + women?
Men:
- Usually asymptomatic
- Sometimes urethritis
Women:
- Discharge (yellow-green)
- STRAWBERRY CERVIX
How is trchomoniasis diagnosed?
- Wet prep microscopy (flagellated organisms seen)
- PCR
What is the treatment for trichomoniasis?
Metronidazole
What is trichomoniasis associated with?
Increased risk of HIV infection (due to mucosal damage)
What is the causative organism for bacterial vaginosis?
- Abnormal vaginal flora
- Polymicrobial
- Decreased lactobacilli
What are the symptoms associated with bacterial vaginosis?
- Watery discharge
- Odour
What is the cause of bacterial vaginosis?
- Sexually associated not transmitted
- A/w hygiene practices (soaps)
How is bacterial vaginosis diagnosed?
- Microscopy of gram stain
- Raised pH
- Whiff test
- CLUE CELLS
What is the treatment for bacterial vaginosis?
- Lifestyle: just use water for washing (no soaps)
- Metronidazole PO/topical
What is the causative organism for Candidiasis?
- Candida albicans (years)
What is the presentation of candidiasis in men + women?
General:
- Thick, white discharge (cottage cheese)
- Itching
- Soreness
- Redness
Women:
- Vulvovaginitis
Men:
- Balanitis
What is candidiasis associated with?
- NOT STD (can be part of normal flora)
- Immunodeficiency (e.g. pregnancy, DM0
- Hygiene practices
How is candidiasis treated?
- PO/topical antifungals (e.g. clotrimazole/fluconazole)
What is the causative oragnism of Molluscum contagiosum?
- Pox virus, dsDNA
How does molluscum contagiosum present and how does it spread?
General:
- Small papules with central punctum
Children:
- Hands + faces
- Spread = skin-to-skin contact
Adults:
- Genital lesions
- Spread = sexual contact
Immunocompromised:
- Widespread lesions
What is the treatment for molluscum contagiosum?
- Usually no Tx
- If persistent/severe: Cryotherapy
What is the causative organism for genital warts?
- dsDNA Human Papillomavirus
- HPV 6 / HPV 11
How is genital warts diagnosed?
Clinical Dx:
- Papular
- Planar
- Pedunculated
- Carpet
- Keratinised
- Pigmented
How are genital warts treated?
Home:
- Podophyllotoxin solution/cream (not suitable for pregnant women)
Clinic:
1. Cryotherapy
2. Imiquimod
What are some viral STIs?
Hepatitis
- HAV: (Oro-anal sex)
- HBV
- HCV (Mainly HIV +ve MSM)
Herpes
HIV
How does HSV present?
- Painful ulcers
- No lymphadenopathy
