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HUMAN HEALTH AND DISEASE > Sexually Transmitted Infections (STIs) > Flashcards

Sexually Transmitted Infections (STIs) Flashcards

1
Q

What is an STI?

A

An infection spread by sexual contact

Those with sexual contact as the sole/predominant mode of transmission would cover chlamydia & gonorrhoea.

Those with other modes would include Hep A, B, C, and HIV

Not called STD because STIs are not always symptomatic.

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2
Q

What are some risk factors for STIs?

A

-Young age (especially <20yrs)
-Single
->2 partners in preceding 6/12
-Use of non-barrier contraception
-Residence in inner city
-Symptoms in partner
-Current STI & history of previous STIs
-Sexual orientation
-Chemsex

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3
Q

Summarise the main STIs and the pathogenic cause of each.

A

Bacterial:
-Chlamydia
-Gonorrhoea
-Syphilis

Viral:
-Genital herpes
-Genital warts
-HIV

Fungal:
-Candidiasis

Parasitic:
-Pediculosis Pubis
-Genital Scabies

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4
Q

What host defences does our body have and how do the microbes overcome them?

A

look at the slides

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4
Q

What is the causative organism in chlamydia and describe it?

A

Chlamydia trachomatis

It’s an obligate intracellular bacterium

Has extracellular (elementary body) and intracellular (reticulate body) forms

There are multiple serotypes of it, including A-K and L1, L2, & L3 (D-K are genital & L types are LGV)

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5
Q

Is chlamydia transmission common?

A

Yes, it’s the most common STI in the UK

Also congenital transmission is well-recognised, and that can also cause neonatal conjunctivitis in 30-50% of cases (and very rarely, you can get pneumonitis).

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5
Q

How does the chlamydia bacterium enter the body?

A

It binds to specific receptors and enters via parasite-specified endocytosis.

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6
Q

What are the signs and symptoms of chlamydia in females?

A

Symptoms:
-80% asymptomatic
-PV bleeding/purulent discharge/lower abdominal pain/dyspareunia/proctitis

Signs:
-Normal
-Cervicitis (discharge/contact bleeding)/adnexal tenderness

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7
Q

What are the signs and symptoms of chlamydia in males?

A

Symptoms:
-50% asymptomatic
-Urethral discharge/dysuria/testicular pain/proctitis

Signs:
-Normal
-Urethral discharge

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8
Q

What are some potential complications of chlamydia?

A

Female:
Ascending infection can lead to pelvic inflammatory disease (PID)

PID =endometritis/salpingitis/tubule damage/chronic pelvic pain

Increased risk of ectopic pregnancy (pregnancy outside the uterus) and infertility

Male:
Epididymitis
In either auto-inoculation may cause chlamydial conjunctivitis

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9
Q

How do you diagnose and treat chlamydia?

A

Diagnosis:
-Nucleic acid amplification testing (NAAT)
-High sensitivity and specificity for genital sites
-Also used for extra-genital sites (rectal/pharyngeal/ophthalmic)

Treatment:
-Azithromycin 1g STAT
-Doxycycline 100mg BD 7/7

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10
Q

What is the causative organism of gonorrhoea and describe it?

A

Neisseria gonorrhoea

Gram negative diplococci which are facultatively intracellular

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11
Q

By what method does the bacterium in gonorrhoea enter the body?

A

Site of entry = mucosal surfaces (vaginal / urethral / rectal)

Adhesive mechanism ensures it evades mechanical removal by secretions

Produces IgA protease to disable host secretory antibodies

Replicates in intracellular vacuoles which fuse with basement membrane releasing bacterium into connective tissue

Elicits host inflammatory response with resultant tissue damage

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11
Q

Can gonorrhoea be transmitted congenitally?

A

Yes and can result in neonatal conjunctivitis

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12
Q

What are the signs and symptoms of gonorrhoea in females?

A

Symptoms:
-70% asymptomatic
-Vaginal discharge
-Low abdominal or pelvic pain

Signs:
-Urethral discharge
-Cervicitis
-Cervical discharge
-Cervical excitation

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13
Q

What are the signs and symptoms of gonorrhoea in males?

A

Symptoms:
-85% with urethral infection develop symptoms in 10/7
-Commonly discharge or dysuria
-Rarely asymptomatic

Signs:
-Meatitis
-Urethral discharge

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14
Q

What are some extra-genital sites that can be affected by gonorrhoea?

A

-Conjunctivitis
-Pharyngitis
-Pharyngeal exudate
-Proctitis
-Rectal discharge

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15
Q

How do you diagnose and treat gonorrhoea?

A

Diagnosis:
-NAAT as per Chlamydia
-Due to resistance always perform culture and sensitivity

Treatment:
-Depends on local guidelines and resistance pattern
-Ceftriaxone 500mg IM STAT + –Azithromycin 1g PO STAT

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16
Q

What are some potential complications of gonorrhoea?

A

Female:
-Bartholinitis (inflammation of bartholin glands)
-Endometritis (Inflammation of endometrium)
-Salpingitis
-Peritonitis (inflammation of the peritoneum)
-Tubo-ovarian abscess

Male:
-Epididymitis
-Local abscess formation

Very rarely, it can disseminate further and cause septicaemia, arthritis, or skin lesions

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17
Q

What is the causative organism of syphilis and describe it?

A

Treponema pallidum

Motile spirochaete

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17
Q

How is syphilis transmitted?

A

Sexual contact

Can also be transmitted transplacentally (microbes from a pregnant woman’s bloodstream cross the placenta and enter the bloodstream of the fetus)

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18
Q

What are the stages of syphilis?

A

Primary, secondary, tertiary

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19
Q

Describe the features of primary syphilis.

A

10-90 days post-exposure

Develop papule at site of inoculation

Ulcerates and becomes painless, firm chancre

May go unnoticed (cervical/rectal ulcer)

Spontaneous resolution within 2-3 weeks

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19
Q

How do you treat syphilis?

A

Penicillin G, administered parenterally, is the preferred drug for treating persons in all stages of syphilis.

Dosage, and length of treatment depend on the stage and clinical manifestations of the disease.

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20
Q

Describe the features of secondary syphilis.

A

4-10 weeks

Constitutional symptoms (fever/sore throat/malaise/arthralgia)

Generalised lymphadenopathy

Generalised skin rashes (classically palms and soles)

Condylomata lata (warty, plaque-like lesions typically peri-anal region)

Superficial confluent ulceration of mucosal surfaces (‘snail track ulcers’)

Acute neurological signs (aseptic meningitis)

Without treatment, resolves after 3-12 weeks (gives false sense of security)

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21
Q

Describe the features of tertiary syphilis.

A

Years after inoculation

Gumma (granulomatous, ulcerating lesions) affecting skin typically at sites of trauma

Can affect bone and visceral organs

Cardiovascular manifestations (aorititis/aortic regurgitation)

Neurosyphilis also occurs (affecting nervous system)

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22
Q

How do you diagnose syphilis?

A

-Dark field microscopy (definitive diagnostic method)

Presumptive diagnosis of syphilis requires 2 tests:

-Treponemal specific

-Non-treponemal specific

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23
Q

What is the causative organism in genital herpes?

A

Herpes simplex virus (HSV) types 1 & 2 (both can infect mouth or genitals).

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24
Q

How is genital herpes transmitted?

A

-Close physical contact (sexual or oro-genital)

-Viral shedding by infected partner

-Sporadic (irregular), not necessarily associated with symptoms

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25
Q

What are the symptoms and signs of genital herpes?

A

-It’s variable

-You can get a severe primary episode within 2-12/7 of acquisition

-70-80% asymptomatic

26
Q

What are potential complications of genital herpes?

A

Very rarely, you can get acute urinary retention/constipation /aseptic meningitis.

26
Q

What can the first severe clinical episode (does NOT necessarily imply recent infection) of genital herpes include?

A

-Febrile illness (prodrome) 5-7 days
-Dysuria, urinary frequency
-Painful inguinal lymphadenopathy
-Tingling/neuropathic pain (genitals/buttocks/legs)
-Genital blisters, ulcers, fissures
-Untreated episode may last 3 weeks

26
Q

What are some risk factors for genital herpes?

A

-Age (<20yrs)
-Severe 1st episode
-Occurs within 3 mths of 1° episode
-HSV type 2
-HIV or other immunodeficiency

27
Q

What are the symptoms & signs of reactivated genital herpes?

A

-Recurrent episodes usually mild
-Neuropathic prodrome (tingling/burning)
-Erythema/blisters/fissures/ulcers
-Resolution within 3-4 days

28
Q

How do you diagnose genital herpes?

A

Swab for HSV PCR (false negatives)

Do not delay treatment for results

Serology rarely performed

29
Q

How do you treat primary genital herpes?

A

Usually settles within 5-7 days or beyond but new lesions

Aciclovir 200mg x5/day for 5-7 days

Analgesics/bathing in dilute saline solution/laxatives if required

29
Q

How do you treat reactivated genital herpes or frequent/prolonged herpes?

A

Reactivation:
Analgesics/saline washes/petroleum jelly to lesions

Frequent/prolonged:
>6 episodes/yr or episodes last> 4 days at a time
Consider prophylactic therapy

30
Q

What is the causative organism of genital warts and describe it?

A

Human papillomavirus (HPV)

-Over 80 types of which 30 associated with genital infection
-Most common 6, 11, 16, 18, 31 and 33

31
Q

What is the incubation period for genital warts?

A

3-18mths (can be longer)

Frequently transmitted without presence of visible wart

31
Q

How are genital warts transmitted?

A

-Close physical contact (skin to skin)
-Almost always genital for genital warts
-Auto-inoculation from other sites is rare

32
Q

Where are genital warts commonly seen in males & females?

A

Female:
-Commonly in vulva/perianal region/cervix
-Less commonly in vagina/urethra

Male:
-Commonly penis/urethra/perianal region (regardless of sexual behaviour) /scrotum

32
Q

What are the signs & symptoms of genital warts?

A

-Genital lumps (hard/soft, solitary/multiple)
-Bleeding (typically urethral)
-Itchiness
-Hyperpigmentation

33
Q

How do you diagnose & treat genital warts?

A

Diagnosis:
-Clinical appearance
-Occasionally biopsy required

Treatment:
-Eradicate visible warts– NOT virus
-Podophyllotoxin cream for external warts
-Weekly cryotherapy

34
Q

What are the complications of HPV?

A

12 HPV types, most high risk include: 16,18,31,45.

Linked to number of cancers

Strongest association with cervical cancer

34
Q

What is the causative organism of HIV and describe it?

A

Human immunodeficiency virus

Member of lentovirus group of retrovirus family

Two types:
HIV-1 (most virulent)
HIV-2 (almost entirely West Africa)

35
Q

What are the 3 major structural genes in HIV?

A

Gag- encodes nuclear proteins

Pol- encodes viral enzymes (reverse transcriptase, integrase, protease)

Env- encodes envelope glycoproteins

36
Q

Describe the structural components of HIV and what they do.

A

look at the slides

37
Q

What are the steps in HIV replication?

A

Viral replication:

  1. Complementary DNA (cDNA) strand produced from viral DNA by reverse transcriptase
  2. Second cDNA strand synthesised
  3. cDNA transported to cytoplasm
  4. Integrase cleaves cDNA and inserts into host genome
  5. Viral products transcribed by host cell
  6. Cleaved into proteins by HIV protease enzyme
  7. Assemble into new virus
  8. Virus buds from cell surface
38
Q

What kind of immune responses do you get with HIV?

A

Humoral response:
B cells produce a ‘neutralising antibody’ against gp120 in all patients but this fails to clear the virus

Cytotoxic response:
Cytotoxic lymphocytes can control HIV replication in early infection but this is eventually overcome by progressive damage to the immune system

39
Q

What is the natural history of HIV by primary infection (seroconversion)?

A

-60% develop symptoms of seroconversion (often mild)

-Usually 2-6 weeks after infection

-Diagnosis of primary is important

-May not be unwell again until late in infection

-Prevent onward transmission

-Treatment

40
Q

What are some signs & symptoms of HIV infection?

A

-Fever
-Sore throat
-Malaise
-Arthralgia/myalgia
-Lymphadenopathy
-Oro-genital ulceration
-Rash
-Headache
-Diarrhoea
-Oral candida

41
Q

Describe HIV classification:

A

Classified as A, B, or C
-lowest CD4 count determines the class
-Stay in that class even if CD4 levels begin to rise

42
Q

Describe category C of HIV.

A

Much more unusual infections.

42
Q

Describe categories A & B of HIV.

A

A:
-Persistent generalised lymphadenopathy

B:
-Candidiasis (oral)
-Herpes zoster involving min 2 episodes of more than one dermatome
-Oral hairy leukoplakia

43
Q

What diagnosis and tests can you do to diagnose HIV?

A
  1. HIV antibody test:
    -Standard test
    -Can take up to 3mths to become positive
  2. HIV p24 antigen (superseded by antibody test):
    -Detects viral antigen rather than antibody
  3. CD4 count (CD4 or helper T lymphocytes):
    -Most useful indicator of current immune status

4.HIV load (viral load / HIV RNA):
-Current lower limit of detection <40 copies/ml (undetectable)

5.HIV genotype:
-Baseline as useful for choice of ART and then again after failure of ART

44
Q

How can you treat HIV?

A
  1. Nucleoside Reverse Transcriptase Inhibitors:
    -Mimic naturally occurring molecules
    -Prevent attachment of next chain resulting in DNA breakage
  2. Non-Nucleoside Reverse Transcriptase Inhibitors:
    -Disparate group of drugs which fit into a molecular cleft, with reverse transcriptase which reduces catalytic activity
  3. Protease Inhibitors:
    -Inhibit the enzyme required for post-translational modification of viral gene products

4.Integrase Inhibitors:
-Block integration of HIV DNA into genome

  1. Co-receptor antagonists
45
Q

What is the causative organism of genital candidiasis?

A

Candida albicans (80-90%)

Debatable as to whether its an STI or not

46
Q

What is the risk of transmission of HIV post-exposure?

A

Risk of transmission= risk source of HIV x risk of exposure

46
Q

When should you start HIV treatment?

A

The previous guidance was to start based on CD4 count <350 cells/microlitre but the current guidance is to start ART regardless of CD4 count.

47
Q

What are the symptoms & signs of genital candidiasis?

A

Symptoms:
-Pruritis (itching)
-Discharge
-Burning sensation

Signs:
Female- erythema & vulval swelling; adherent white discharge
Male- erythema; discharge

47
Q

What are some risk factors for genital candidiasis?

A

-Pregnancy
-Antibiotic therapy
-Diabetes mellitus
-Immunodeficiency (HIV/drugs/chemotherapy)

48
Q

Is genital candidiasis an STI?

A

There is debate around the matter as to whether it is a pathogen at all or merely an overgrowth &
overdevelopment of the commensal organisms

The same argument is held in the oral cavity around oral candidiasis

49
Q

How do you diagnose & treat genital candidiasis?

A

Diagnosis:
-Clinical
-Can be confirmed by microscopy and culture (+/- sensitivity)

Treatment:
-Topical- Clotrimazole 1% cream
-Systemic- Fluconazole 150mg STAT

50
Q

What is the causative organism of pediculosis pubis (pubic lice)?

A

-Phythirus pubis

-This is distinct from other human lice

51
Q

How is pediculosis pubis transmitted & what are the signs & symptoms?

A

-Transmitted by close bodily contact

-Symptoms & signs include itching

52
Q

How do you diagnose & treat pediculosis pubis?

A

Diagnosis:
-Visualised on skin
-Nits (eggs) adhere tightly to pubic hair
-Highly characteristic under low-power microscope

Treatment:
-0.5% malathion
-1% permethrin
-Applied to entire body
-May require repeating after 1 week

53
Q

What is the causative organism of genital scabies?

A

Mite- Sarcoptes scabiei

54
Q

How is genital scabies transmitted?

A

Prolonged close contact (not isolated to sexual contact).

55
Q

What are the symptoms & signs of genital scabies?

A

Symptoms:
Pruritis (worse at night)

Signs:
-Itchy, red papules (occasionally vesicles and pustules)

Can occur anywhere on skin (rarely face): web of fingers and toes; palms and soles; wrists and axilla; male genitalia; around nipples and umbilicus

Excoriations and 2° bacterial infections

56
Q

How do you diagnose and treat genital scabies?

A

Diagnosis:
-Skin scraping

Treatment:
-0.5% malathion
-1% permethrin
-Applied to entire body
-May require repeating after 1 week

Pruritis often persists for up to 4 weeks post-treatment

57
Q

What is important to consider when taking sexual history?

A

-Privacy
-Permission
-Do not make assumptions
-Use right terminology

58
Q

How do you take a patient’s sexual history?

A
  1. History
  2. Presenting complaint
  3. History of presenting complaint:
    -Male (discharge/sores/ulcers/dysuria/testicular pain/ED)
    -Female (discharge/itching/pelvic pain/PV bleeding/dysuria/sores/ulcers/dyspareunia)
  4. Partners:
    -Sexually active/last sexual intercourse/contraception (barrier)/type of sex/regular or casual partner/no. of partners in last 3mths/same sex/overseas
59
Q

What is the relevance of STDs to a dental practitioner?

A

Oral presentation- mainly HIV and syphilis diagnoses in unaware patients.

HUMAN HEALTH AND DISEASE (58 decks)

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