MB12 Sexually Transmitted Infections - Mucosal Flashcards Preview

Pathology > MB12 Sexually Transmitted Infections - Mucosal > Flashcards

Flashcards in MB12 Sexually Transmitted Infections - Mucosal Deck (36):
1

What are the key mucosal STIs and what are the the agents causing each one?

Syphillis - Treponema pallidum

Gonorrhea - Neisseria gonorrhoeae

Non-specific urethritis - Chlamydia trachomatis

Genital Warts and Dysplasias, Cervical Carcinoma - Papillomaviruses

Genital herpes - Herpes simplex virus (type 1 and 2)

2

The incidence of most STIs is increasing, why?

1.increasing density and mobility of human populations

2.the difficulty of engineering changes in human sexual behavior

3.the absence of vaccines for almost all STDs. 

3

  • Why is assymptomatic infection important in terms of STIs?
  • Give examples

Many STIs are associated with minimal or no symptoms in a proportion of those affected

  • Gonorrhoea and Chlamydia especially in female
  • HIV in latent asymptomatic period
  • HBV in 50% of adults 

4

What are the general principles of management of bacterial STIs?

  • Contact tracing
  • Antibiotic treatment
  • Advice regarding safe sex
  • With STDs - possibility of multiple infection must be borne in mind. 

5

What is Syphillis? (4 Stages)

  1. Primary (2-6wks) Primary chancre, enlarged lymph node, painless ulcer, spontaneous healing. Proliferation in lymph node
  2. Secondary (1-3months) Flu like illness and rash. Bacteraemia
  3. Latent (3-30years) Dormant. Can get reactivation and host response. Bacteria in liver and spleen in low numbers
  4. Tertiary Neurosyphilis or Cardiovascular syphilis. Reactivation and host response

(Less common than some the STIs, 6 cases per year in NI)

(Initially in Gay men - Later spread into heterosexual including antenatal.)

(Pre-penicillin, it was fatal)

6

What causes Syphillis?

Treponema pallidum

7

  1. What is congenital syphillis? When is it acquired?
  2. What can the disease manifest as?
  3. How are women screened?

  1. An infected woman can transmit T. pallidum to her baby in utero. Acquired after the first 3 months of pregancy.
  2. serious infection resulting in intrauterine deathcongenital abnormalities which may be obvious at birth or silent infection, which may not be apparent until about 2 years of age (facial and tooth deformities)
  3. All women in UK are screened (VDRL or EIA) in pregnancy as part of antenatal booking tests

8

Describe the microbiology of syphillis

•Spirochete

(spiral bacteria)

Treponema pallidum

–closely related to the treponemes that cause the non-venereal infections of pinta and yaws

9

What is the laboratory analysis of Syphilis?

(T.pallidum cannot be grown in vitro)

What is the key diagnosis?

Microscopy

Exudate from the primary chancre should be examined by either:

dark-field microscopy

UV microscopy after staining with fluorescein-labeled antibodies.

The organisms have tightly wound, slender coils with pointed ends and are sluggishly motile in unstained preparations.

T. pallidum is very thin and cannot be seen in Gram-stained preps.

Silver impregnation stains can be used in biopsy material.

Serology = Key diagnosis

•Serologic tests for syphilis are the mainstay of diagnosis.

–non-specific and specific tests for the detection of antibodies in patients' serum. 

10

Syphilis Serology 

  1. What is the Non-Specific test?
  2. What issues does it have?
  3. What is it useful for?
  4. What does it indicate?

  1. Non-specific test (e.g. VDRL) (Human antigen) Cheap – used to be used for screening
  2. Specificity problems (false positive reactions)
  3. Goes negative after successful treatment so useful for assessing response to therapy
  4. Indicates active infection

11

Syphilis Serology 

  1. What is a specific test?
  2. What is it useful for?
  3. What can it be used to do and why?
  4. What stage of infection is it used for?
  5. What is it not useful for?

  1. e.g. IgG EIA (Treponemal antgen)

  2. screening

  3. Can be used to confirm the non-specific test, as there are less specificity problems

  4. Late infection - stays positive for life

  5. Not useful for assessing response to therapy

12

In Syphilis Serology testing, why is a combination of the two tests used (non-specific and specific)?

•Specific Test (e.g. IgG EIA)

–Treponema palidum IgG EIA (Enzyme immunoassay)

For screening

Non-specific test (e.g. VDRL)

For assessing disease activity and response to treatment

–Only done if the screening test is positive

13

  1. What is the treatment for syphilis?
  2. What do you give to patients who are allergic to penicillin?
  3. What about congenital syphilis?
  4. What does prevention of 2o andn 3o disease depend upon?
  5. What should be conducted in conjunction with treatment?

  1. Penicillin
  2. tetracycline or doxycycline
  3. preventable if women are screened serologically early in pregnancy (<3 months) and those who are positive are treated with penicillin. Only penicillin therapy reliably treats the fetus when administered to a pregnant mother.
  4.  early diagnosis and adequate treatment.
  5. Contact tracing with screening with treatment

14

Gonorrhea 

  1. What is a major reservior of infection?
  2. Who is most at risk?
  3. How else can it be transitted?
  4. How does infection in babies usually manifest?

  1. Asymptomatically infected individuals (usually women)
  2. Female has a 50% chance of becoming infected after a single sexual intercourse with an infected man, while a man has a 20% chance of acquiring infection from an infected woman.
  3. Usually manifests as ophthalmia neonatorum

15

Gonorrhea

  1. What are the first clinical symptoms?
  2. When do symtoms usually develop?
  3. What is a particular issue for women?
  4. What are the late complications in women?

  1. male: urethral discharge & pain passing urine (dysuria)

    female: vaginal discharge. 

  2. Within 2-7 days

  3. Asymptomatic infection - important factor in complications (i.e. the infection is unrecognised and untreated). At least 50% of all infected women have only mild symptoms or are completely asymptomatic. 

  4. –pelvic inflammatory disease (PID)

    –chronic pelvic pain

    –Infertility

16

What is ophthalmia neonatorum?

Characterized by a sticky discharge from eyes and URTI

(manifestation of Gonorrhea

17

What are some of the clinical implications of Gonorrhea

•Ophthalmia neonatorum - a sticky discharge from eyes and URTI.

•Throat infection of the may result in a sore throat

•Rectal infection- proctitis- purulent discharge.

•Invasive gonococcal disease

–much more common women than in men 5% of people with disseminated infection have deficiencies in the late-acting components of complement

–prompt treatment is important in containing local infection. 

18

What organism causes Gonorrhea?

•Neisseria gonorrhoeae

–(the 'gonococcus')

–Gram-negative coccus - present in pairs

•Sensitive to drying

–intimate mucosal contact required transmission.

19

How is a diagnosis of Gonorrhea made?

  1. What is seen on microscopy?
  2. What can be seen on a culture of agar
  3. What is the most sensitive test?

microscopy and culture of appropriate specimens but this has largely been replaced by PCR

  1. Gram negative diploccoci on microscopy - Quick, can be done in the clinic
  2. Culture of N. gonorrhoeae on chocolate agar - Allows sensitivity testing

  3. Molecular testing (PCR)

    Most sensitive method, now readily available 

20

What samples are taken to make a diagnosis of Gonorrhea?

  1. For Females
  2. For Males
  3. What other STD does this approach also apply to?

  1. genital (vulvo-vaginal) or cervical swabs (urine less sensitive in females)

  2. Males urine - Urethral swabs not generally necessary

  3. Chlamydia 

21

  • What is the treatment for Gonorrhea?

 

  • What type of infection is this suitable for?

  • Antibiotics - Ceftriaxone 500 mg intramuscularly as a single dose with azithromycin 1 g oral as a single dose.(Azithro to cover chlamydia) 
  • This is for Uncomplicated infection

    Longer regimens and addition of other drugs for Eye/epididimitis/disseminated etc

 

22

Describe the epidemiology of Chlamydia

 

Much more common than syphilis or gonorrhoea

23

Describe the microbiology of Chlamydia?

Small bacteria.

Obligate intracellular organism

–EB (Elementary Body)

–extracellular survival and for initiation of infection

–RB (Reticulate Body)

–intracellular multiplication

•Clamydia trachomatis

24

What is the serotype of, and where are they present? 

  1. The common chlamydial STIs?
  2. Trachoma (non-STI)
  3. Lymphogranuloma venereum  

  1. D-K (Worldwide)
  2. A, B and C (Africa)
  3. L (Restricted)

25

C trachomatis serotypes D-K

What are the common clinical effects and complications...

 

  1. For men
  2. For women
  3. For neonates

  1. •Urethritis

    •Epididimitis

    •Proctitis

    •Conjnuctivitis

    1. Complications: 

      •Reiters syndrome

      –1 arthritis, 2 urethritis, & 3 conjunctivitis

  2. •Urethritis

    •Cervicitis

    •Proctitis

    •Conjnuctivitis

    Complications: Ectopic pregnancy, Infertility

  3. Pneumonia 

 

26

How is Chlamydia diagnosed?

 

  • For what are lab tests essential in distinguising?

Nucleic acid tests (NAT)

PCR and other methodologies = sensitive

•Older methods (Culture in cell culture & Antigen detection are not really used now)

 

  • Chlamydial urethritis and cervicitis - they cannot be distinguished from other causes of these conditions on clinical grounds alone

 

27

  1. What is the treatment for C.Trachomatis?

 

What is the treatment for pregnant women and babies?

  1. Azithromycin- Single dose, Doxycycline -7 days
  2. Erythromycin 7 days for pregnant women and babies

28

Lymphogranuloma venereum  LGV

(C.Trachomatis serotype L)

  1. Where is this disease serious?
  2. What does it involve?
  3. What antibiotics are given?

  1. Africa, Asia and South America
  2. systemic infection involving lymphoid tissue

    –Primary lesion (ulcerating genital papule)

    –fever, headache and myalgia

    –Followed by inguinal (and other) lymph nodes-buboes

  3. Doxycycline or erythromycin 

29

  1. What causes Genital Herpes?
  2. What are the two types of HSV?
  3. What is HSV-1 associated with?
  4. What is HSV-2 associated with?
  5. Which is the most common? Why?

  1. Herpes simplex virus
  2. HSV-1 & HSV-2

  3. oral and genital infections (Also causes HSV encephalitis)

  4. genital infection only  (But can get severe generalised infection in neonate and meningitis in adults.)

  5. HSV-2 was the most common cause of genital herpes, but in Northern Ireland HSV-1 is now detected more frequently. (may be due to more orogenital practices

30

Genital Herpes

  1. What does it present as?
  2. What are the other symptoms?
  3. When is it apparent from?

  1. Genital ulcerating vesicles that can take up to 2 weeks to heal. Vesicles (blisters) that break down to form painful shallow ulcers
  2. Local lymph nodes are swollen, Constitutional symptoms: fever, headache and malaise., Occasionally urethral lesions -dysuria.

  3. The primary genital lesion on the penis or vulva is seen 3-7 days after infection.

31

What is the pathogenesis of Genital Herpes?

  • At primary infection the virus travels up sensory nerve endings to establish latent infection in dorsal root ganglion neurones
  • From this site it can reactivate, travel down nerves to the same area, and cause recurrent lesions ('genital cold sores') - Recurrent genital herpes

32

How are Genital Herpes diagnosed?

•Clinical

•Laboratory

–Culture, antigen detection, PCR - PCR most sensitive assay and is now the standard approach to diagnosis

33

Genital Herpes

  1. What is the treatment?
  2. What may also be effective?

  1. Acyclovir (and related drugs valaciclovir and famciclovir)
  2.  
    1. Acute treatment of primary or reactivation episode
    2. Pre-emptive treatment starting treatment at prodromal symptoms before rash appears
    3. Suppression treatment may be necessary in persons with frequent recurrences

34

  1. What is HPV?
  2. What is it associated with?

  1. human papillomaviruses
  2. all infecting skin or mucosal surfaces –Non genital warts, Genital Warts, Association with cervical carcinoma (and other genital carcinomas)

35

  1. What causes Genital Warts?
  2. What is another name for genital warts?
  3. Where do they present?
  4. What is it associated with?

  1. Human Papillomavirus
  2. condylomata acuminata
  3. penis, vulva and perianal regions

    –Typical incubation period of 1-6 months

    –Often regress months/years later

    –can be treated with podophyllin.

    lesion on the cervix

    –flat area of dysplasia visible by colposcopy as a white plaque after the local application of 5% acetic acid .

     

  4. Associated with cervical cancer,

    •especially types 16 and 18,

    •cervical lesions are removed by laser or loop excision. 

36

Case

 

21 year old male returns from holiday in Ibiza.

Symptoms:

–Several days history of dysuria and purulent penile discharge.

  1. What investigations are necessary?

  1. •Urine- chlamydia (NAT) test

    •N gonorrhoeae NAT test too

    •Swab for N gonorrhoeae microscopy culture

    •Think other STIs? Blood tests, follow-up