Microbiology - STIs Flashcards by Annie Rees

What are some common presentations of man with an STI?

Asymptomatic
Urethral discharge
Dyrsuria
Scrotal pain/swelling
Rash/sores
Systemic Sx

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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

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What are some common causes of discharge?

Gonorrhoea
Chlamydia
Trichomonas
Candida
Bacterial Vaginosis

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What are some common causes of ulceration?

Syphilis (Painful)
HSV (painless)
LGV
Chancroid
Donovanosis

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What are some common causes of rashes, lumps/growths?

Genital warts: HPV
Molluscum contagiosum
Scabies
Pubic lice

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What is the causative organism of gonorrhoea?

Neisseria gonorrhoeae
- Obligate intracellular gram -ve diplococci

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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

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What is the most common presentation of an uncomplicated gonorrhoeal infection (90%) in a woman?

Mucopurulent cervicits:
- Erythema + oedema
- Urethra (vaginal leakage)

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What is a common presentation of a complicated gonorrhoeal infection (10%) in a man?

Prostatitis

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What is a common presentation of a complicated gonorrhoeal infection (10%) in a woman?

PID (salpingitis)
- Ascending infection

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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

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What is the gold standard investigation for diagnosing gonorrhoea?

Urethral (Sens: 95%) / Rectal (Sens: 20%) smears
- Produces a culture

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What is the treatment for gonorrhoea?

IM Ceftriaxone (250mg) Single Dose

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What is the causativ organism for chlamydia?

Chlamydia trachomatis
- Obligate intracellular gram -ve pathogen
- Can’t be cultured on agar

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What is the epidemiology of chlamydia?

Common in young adults
10% <25yrs infected in UK (Most common)
Asymptomatic (50% men, 80% women)

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How is chlamydia classified?

Serovars A, B, C: Trachoma (infection of eyes which can cause blindness)
Serovars D-K: Genital chlamydia, opthalmia neonatorum

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How is chlamydia diagnosed?

NAAT (nucleic acid amplification test) from genital swabs

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What is the treatment for chlamydia?

Azithromycin 1g Stat
OR
Doxycycline 100mg BD (7/7)

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What are some complications of Chlamydia?

PID (tubal factor infertility, ectopic pregnancy, chronic pelvic pain)
Epididymitis
Reiter’s Syndrome
Adult conjunctivitis, opthalmia neonatorum

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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

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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)

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How is lympho-granuloma venerum diagnosed?

NAAT
Genotypic identification of L1-3 Serovar

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What is the treatment for lympho-granuloma venerum?

Doxycycline 100mg BD for 3wks

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What is the causative organism of syphilis?

Treponema pallidum
- Obligate gram -ve spirochaete

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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