INF2 - E. STIs-COVERED

Question 1

what are bacterial STIs

Answer 1

• chlamydia
• gonorrhoea
• syphilis

Question 2

what are viral STIs

Answer 2

• HPV
• HSV
• hep B
• HIV

Question 3

what are parasitic STIs

Answer 3

• trichomoniasis

Question 4

chlamydia

Answer 4

• caused by chlamydia trachomatis
• gram -ve bacteria
• most common
• 7-8% <25 in UK infected
• 70% women and 50% men show no symptoms
• regular screening and barrier contraception

Question 5

life cycle of chlamydia

Answer 5

• bacterium exists in elementary body (infectious) and the reticulate body (intracellular and can replicate)
• infection starts with EBs attaching to cell membrane of urogenital tract
• EBs enter cell and transformed into RBs which grow and divide over next hours
• RBs transform into EBs and 2-3 days after infection, host cell bursts to release more infectious EBs

Question 6

symptoms of chlamydia in men

Answer 6

• untreated: can cause urethritis and chronic prostatitis
• poorer sperm quality so fertility affected
• mucus-like or clear, watery discharge
• painful/burning urination

Question 7

symptoms of chlamydia in women

Answer 7

• urethritis, PID, scarring in pelvis (uterus and fallopian tubes)
• effects on fertility
• ectopic pregnancy, miscarriage, premature rupture of membranes
• white/yellow/gray discharge: smelly
• painful intercourse
• bleeding in between periods
• increase urination
• painful/burning urination
• pus in urine
• painful periods
• dull pain in lower abdomen
• itching/burning in and around vagina

Question 8

screening and diagnosis of chlamydia

Answer 8

• NAATs and cell culture
• females: vaginal swabs
• males: urine tested

Question 9

gonorrhoea

Answer 9

• caused by neisseria gonorrhoeae
• gram -ve diplococcus bacterium
• infects mucus membranes of reproductive tract
• often asymptomatic
• regular screening, free test kits

Question 10

life cycle of gonorrhoea

Answer 10

• adhere to host epithelial cells
• replicates and forms micro colonies, colonising and invading epithelium tissue
• bacteria release molecules that activate macrophages and dendritic cells
• activation of inflammatory transcription factors and release of cytokines and chemokines
• pro-inflam mediators trigger neutrophils
• neutrophils phagocytose bacteria
• purulent exudate aids transmission (bad!)

Question 11

symptoms of gonorrhoea in men

Answer 11

• untreated: urethritis and epididymitis
• infertility in rare cases
• white/green/yellow discharge from penis
• testicular pain and swollen testicles
• painful/burning urination
• sore throat
• itchy, pain when poop
• can spread to blood: disseminated gonococcal infection - life threatening

Question 12

symptoms of gonorrhoea in women

Answer 12

• spread to uterus/fallopian tubes = PID
• fertility
• ectopic pregnancy
• white/yellow discharge
• pain during intercourse
• bleeding between periods
• painful/burning urination
• pain in lower abdomen/pelvis
• sore throat
• itchy, pain when poop
• can spread to blood: disseminated gonococcal infection - life threatening

Question 13

screening and diagnosis of gonorrhoea

Answer 13

• NAATs and cell culture
• females: endocervical/vagibnal swabs
• males: urine/urethral swabs

Question 14

syphilis

Answer 14

• caused by treponema pallidum
• gram -ve spirochete bacterium
• vertical transmission during pregnancy
• adhere to epithelial cells in genital tract and extracellular matrix components
• regular screening

Question 15

disease progression of syphilis

Answer 15

• infects epithelium, then multiplies locally
• begins to invade lymphatic system and bloodstream
• penetration of BBB in 40% inds with untreated syphilis

Question 16

symptoms of syphilis

Answer 16

primary stage
- genital sores (chancre) develop on genitals

secondary stage
- rash and flu-like symptoms

latent stage
- asymptomatic period but infection still present

tertiary syphilis
- develops in rare subset of untreated infections from 10-30 years after
- multiple organs, fatal
- neurosyphilis
- ocular syphilis
- otosyphilis

Question 17

screening and diagnosis of syphilis

Answer 17

• serologic testing to measure syphilis specific antibodies
• fluid from skin from syphilis sore taken then microscopy

Question 18

HPV

Answer 18

• can be caused by 100 strains of HPV
• infects cells in basal layer of stratified epithelium
• > 30 strains affect genital warts
• harmless which cause genital warts (HPV 6 and 11)
• can progress to cervical cancer (HPV 16 and 18)
• vaccination and cervical screening
• most people don’t know they have it

Question 19

structure of HPV

Answer 19

• naked
• circular dsDNA
• Baltimore group 1
• papillomaviridae
• 60nm
• continued in T=7 icosahedral capsid

Question 20

symptoms of HPV

Answer 20

• depends on strain
• may be asymptomatic
• genital warts
• PAP smear test - may find out
• may develop cancer
• no treatment, can only manage symptoms

Question 21

how to prevent HPV

Answer 21

• vaccine
• safe sex
• protect partner
• screened regularly

Question 22

screening and diagnosis of HPV

Answer 22

• no routine test
• cervical screening (smear test)
• those 25-64 can get

Question 23

herpes

Answer 23

• genital herpes caused by HSV2
• infects epithelial cells and keratinocytes
• asymptomatic
• genital ulcerative disease caused by herpes increases risk of transmission and infection with HIV

Question 24

structure of herpes

Answer 24

• enveloped
• linear dsDNA
• Baltimore group 1
• herpesviridae
• spherical/pleomorphic
• 150 nm
• T=16 icosahedral capsid

Question 25

symptoms of herpes

Answer 25

first outbreak
- sores/lesions on skin and blisters on genitals/rectum/mouth
- vesicles break and leave painful ulcers
- fever, body aches, swollen lymph nodes

recurrent outbreak
- genital pain
- tingling/shooting pain in legs/hips/buttocks
- eruption of herpetic lesions

complications:
aseptic meningitis

Question 26

diagnosis and screening of herpes

Answer 26

• NAATS
• risk of false negatives as viral shedding is intermittent b/n first and second outbreak (dormant stage)
• viral culture, type-specific virolgic tests and serologic tests

Question 27

hepatitis B

Answer 27

• most cases caused by viruses
• excessive alcohol, trauma, injury can cause it
• most cases it only stays in body for 1-3 months (acute)
• can stay for 6 or more months (chronic) , may have no signs
• 25% with chronic have progressive liver disease leading to cirrhosis
• 10% will develop liver cancer
• transmitted by sexual intercourse, bodily fluids (blood and semen)
• blood-to-blood contact (needles, needle stick injuries)
• vertical transmission

Question 28

structure of Hep B

Answer 28

• enveloped
• spherical
• 42nm
• Icosahedric capsule
• baltimore group 7 (dsDNA)
• HepB polymerase has reverse transcriptase activity
• non-retroviral virus which uses transcription as part of replication process

Question 29

why do people get jaundice with hepatitis

Answer 29

• jaundice (icterus) of skin and eyes
• due to increased levels of bilirubin (haemoglobin breakdown product) in blood
• conjugated to form water-soluble bilirubin diglucuronide in healthy liver
• when liver impaired, not good at breaking down RBCs and recycling haem so we make more RBCs
• liver less capable of processing bilirubin

Question 30

symptoms of hepatitis

Answer 30

• jaundice in 80% individuals >14
• less likely in children
• liver cirrhosis is a consequence of chronic liver disease
• fever
• loss of appetite
• nausea and vomiting
• abdominal pain
• weakness and fatigue
• joint pain

Question 31

liver cirrhosis

Answer 31

• fibrosis - liver tissue replacement by collagenous scars with no function
• regenerative nodules attempts to repair damaged tissue
• irreversible damage
• liver transplant

Question 32

screening and diagnosis of hepatitis B

Answer 32

• serologic testing to measure hepatitis B virus specific antigen and antibodies
• triple panel test
  1. hepatitis B surface antigen (HBsAg)
  2. antibody to hepatitis B surface antigen (anti-HBs)
  3. total antibody to hepatitis B core antigen (if +ve, have had hepB. If have immunity from vaccine, don’t have it. Appears at onset of symptoms in acute and doesn’t provide protection against virus)