Sexually transmitted infections Flashcards
what is the most common STI in the UK?
Chlamydia
what are the different types of chlamydia infections?
serotypes A - C - ocular infections - get into eye fluid and causes conjunctivitis
serotypes D-K - genitourinary infections
L1 to L3 - lymphogranuloma venereum (LGV) - emerging infection in men who have sex with men and can cause proctitis
how is chlamydia infection transmitted?
unprotected vaginal, oral or anal sex
from mother to baby through delivery
what is the pathophysiology of chlamydia infection
C.Trachomatis enters the host cell as an elementary body (infectious form) and then becomes a reticular body, the non-infectious form capable of replication
following replication (by binary fission), the reticular bodies form back into elementary bodies and then cell ruptures to release them.
this cases inflammation and tissue damage.
what type of organism is chlamydia?
Chlamydia Trachomatis is a obligate intracellular gram negative bacteria.
what are the risk factors for chlamydia infection?
<25 yrs sexually active e.g. recent change in partner, no. of partners partner with chlamydia co-infection with another STI non barrier methods of contraception
what is the typical incubation period for chlamydia?
7-21 days (from infection to symptoms
what are the clinical features of chlamydia in women?
majority are asymptomatic - especially in lower genital tract
dysuria dyspareunia vaginal discharge post coital and intermenstrual bleeding lower abdominal pain pelvic inflammatory disease - mild to moderate symptoms
signs:
- pelvic tenderness
- mucopurulent endocervical discharge
- cervical excitation
- cervicitis
what are clinical features of chlamydia in men?
urethritis - dysuria and urethral discharge
epididymo-orchitis - testicular pain
signs:
- epididymal tenderness
- mucopurlent discharge
majority asymptomatic
other than typical genitourinary symptoms of chlamydia what other clinical features are there?
conjunctivitis
can infect rectum - discomfort and discharge
can infect pharynx - no symptoms
how is chlamydia infection investigated?
women: vulvovaginal swab (first choice), endocervical swab, first pass urine sample
men: first pas urine sample (first choice), urethral swab
use NAAT on specimen
patients are recommended to have a full STI screen, if you have one STI, you are at risk of others and presentation is similar
contact tracing is required.
there is also a national chlamydia screening programme is England for those <25
how is chlamydia managed?
Abx treatment for uncomplicated urogenital chlamydia infection:
- Doxycycline 100mg twice daily 7 days
- OR Azithromycin 1g single dose
if above are contraindicated an alternative is erythromycin or ofloxacin
advice: avoid sexual contact and oral sex until treatment is complete (7 days after Azithromycin)
should we test chlamydia patients for cure after treatment?
not usually required unless suspected poor compliance, symptoms are persistent or pregnant.
if <25yrs, repeat testing is recommended 3 months after treatment
what are the complications of chlamydia in women?
salpingitis and/or endometritis which can lead to PID
PID can lead to perihepatitis (Fitz Hugh Curtis syndrome)
increased risk of ectopic pregnancy
increased risk of infertility
reactive arthritis and reiters syndrome
what are the complications of chlamydia in men?
infection can spread to epididymitis or epididymoorchitis causing testes to become painful and swollen - if left untreated can affect fertility
reactive arthritis and reiters syndrome
What risks does chlamydia in pregnancy have?
increased risk of premature delivery with low birth weight
increased risk of miscarriage and still birth
if child contracts it they will get neonatal chlamydial conjunctivitis (5-12 days after birth) and possibly develop pneumonia (1 to 3 months after birth)
how are pregnant women and neonates treated for chlamydia?
pregnant women - Abx but doxycycline and ofloxacin are contraindicated. therefore use azithromycin/erythromycin
neonates - oral erythromycin
what is the second most common STI in the UK after Chlamydia?
Gonorrhoea
what type of organism causes Gonorrhoea?
gram negative diplococci
Neisseria Gonorrhoea
how is gonorrhoea transmitted?
oral or vaginal or anal sex that’s unprotected
vertical transmission from mother to child
describe the pathogenesis of gonorrhoea?
the bacteria adheres to mucous membranes of uterus, urethra, cervix, fallopian tubes, ovaries, eyes, testes and throat.
it invades the host cell (intracellular)
causes neutrophils to migrate - abscess forms
it has surface proteins that bind receptors on immune cells to inhibit them.
what are the risk factors for gonorrhoea infection?
<25 yrs Men who have sex with men multiple sexual partners previous gonorrhoea infection high density urban areas
what are the clinical features of gonorrhoea in a females?
dysuria
dyspareunia
abnormal vaginal discharge - thin watery yellow/green
lower abdominal pain
signs: mucopurulent endocervical discharge, pelvic tenderness, easily induced cervical bleeding
what is the incubation period for gonorrhoea?
2-5 days
what are the clinical features of gonorrhoea in men?
dysuria
mucopurulent urethral discharge
signs: discharge and epididymal tenderness
what symptom would you get in gonorrhoea infection of rectum or pharynx?
rectum: discharge, pain/discomfort or asymptomatic
pharynx - asymptomatic
how would you investigate gonorrhoea?
men:
urethral swab/ meatus swab = microscopy and culture
first pass urine - NAAT
women:
endocervical / vaginal swab - NAAT
endocervical / urethral swab - microscopy and culture
NAAT will provide dual testing for gonorrhoea and chlamydia
full STI screen for anyone with symptoms because of symptoms overlapping and same risk factors
how can gonorrhoea be treated?
IM ceftriaxone 500mg and single dose of oral azithromycin 1g
no need to await test results if symptoms are indicative
educate about safe sex
contact tracing
follow up to test for cure
when should you admit a gonorrhoea patient to hospital?
systemic symptoms = malaise, joint pain, fever and rash. this may be indicative of disseminated gonorrhoea infection which could potentially result in meningitis
what are the complications of gonorrhoea?
women: PID, infertility, ectopic pregnancy and chronic pelvic pain
men: spread from urethra to testes and cause epididymo-orchitis which is painful but rarely causes infertility. also Prostatitis
disseminated gonococcal infection - joint pain, rash, meningitis
what are the issues of gonorrhoea infection in pregnancy ?
perinatal mortality
premature labour
early fetal membrane rupture
spontaneous abortion
vertical transmission and cause neonatal gonococcal conjunctivitis (eye pain, redness and discharge)
how can gonorrhoea in pregnancy be treated?
same as non-pregnancy
can give neonate prophylactic Abx
what is pelvic inflammatory disease?
infection of the upper genital tract in females which affects uterus, fallopian tubes and ovaries, caused by infective organisms ascending from the lower genital tract
what is the pathophysiology behind PID?
infections such as chlamydia and gonorrhoea (chlamydia being most common) spread from the vagina and cervix to infect the endometrium, fallopian tubes, ovaries and peritoneum causing inflammation.
some microbes Ecoli and bacteriodes do not cause PID but enhance the infection.
other factors that cause it is instrumentation to the cervix e.g. insertion of coil, gynae surgery, termination of pregnancy
in PID what is the typically path of spread of infection?
cervicitis
endometritis
salpingitis
what are the risk factors for PID?
sexually active non barrier contraception multiple sexual partners age 15-24 previous PID history of STI
immunosuppression
low socioeconomic class low education
what are the clinical features of PID?
can be asymptomatic
lower abdominal pain deep dyspareunia post coital bleeding menstrual abnormalities - IMB, menorrhagia , dysmenorrhoea dysuria abnormal vaginal discharge
more advanced: severe pain, fever , N&V
what is found on vaginal examination of someone with PID?
tenderness of uterus/adnexae or cervical excitation
may be mass in lower abdomen
abnormal vaginal discharge
what are the differentials for PID?
ruptured ovarian cyst endometriosis ectopic pregnancy UTI appendicitis malignancy pelvic abscess
what investigations should be performed for PID?
endocervical swabs - test for gonorrhoea and chlamydia via NAAT
high vaginal swabs - trichomonas vaginalis and bacterial vaginosis
HIV and syphilis screen too
urine dipstick to exclude UTI
pregnancy test
transvaginal USS - if severe and uncertain diagnosis
laparoscopy - severe cases and uncertain diagnosis = gold standard because it allows you to observe the inflammatory changes
what is the CDC criteria for PID?
minimal criteria:
- lower abdominal tenderness
- uterine/adnexal tenderness
- cervical motion tenderness
additional criteria:
- temperature >38.3
- abnormal cervical or vaginal mucopurulent discharge
- white blood cells on microscopy of vaginal secretions
- raised ESR/CRP
- lab results of gonorrhoea, chlamydia or trachomatis
definitive diagnosis:
- histopathological findings of endometritis on endometrial biopsy
- laparoscopic findings consistent with PID
- transvaginal USS or MRI show thickened filled tubes.
how is PID managed?
14 day course of broad spec Abx before results of swabs
- doxycycline, IM ceftriaxone and oral metronidazole
analgesia
avoid sex
contact tracing from last 6 months and give them doxycycline
how is PID treated in pregnancy?
Ofloxacin and metronidazole
cant give doxycycline in pregnancy
when should PID be admitted to hospital?
pregnant - risk of ectopic
severe symptoms
signs of pelvic peritonitis
unresponsibe to Abx or need of IV
what are the prevention strategies
primary: education, adverts
secondary: screen at risk population
tertiary - treat people to reduce spread and complication
what are the complications of PID?
increases chance of ectopic pregnancy and infertility due to scaring of the fallopian tubes and loss of ciliary function and adhesions
tubo-ovarian abscess
chronic pelvic pain
Fitz Hugh Curtis syndrome
peritonitis
periappendicitis
what is Fitz-hugh Curtis syndrome? include symptoms
perihepatitis - spread of PID into peritoneum and then around liver
causes RUQ pain, worse on laughing and coughing
mainly by chlamydia but rare
what is the laparoscopic finding in fitz hugh Curtis syndrome?
Violin string adhesions - due to peritoneum adhering to liver capsule
what type of virus is HIV?
single stranded RNA retrovirus
what is the pathophysiology of HIV?
HIV binds CD4 cells and is uptaken into these cells
the ssRNA genome is then reverse transcribed into DNA by reverse transcriptase
the dsDNA is then inserted into the host cell genome by enzyme integrase.
The host cell then goes onto transcribe and translate as normal but in doing so will produce viral RNA and proteins.
New virus particles can assemble and bud off
the never virus particle matures when the protease cleaves its proteins (after it has left host cell)
the host cell becomes stressed and damaged from this process and thus the virus kills CD4 T cells.
how can the changes in symptoms of HIV be explained? i.e. early on, then later
initially the virus rapidly replicates, killing lots of CD4 cells and thus making the individual feel ill - flu like symptoms.
eventually HIV antibodies are made and viral replication is kept low and number of CD4 cells remains stable - latent phase - asymptomatic
years later eventually immune system cant keep up and CD4 cells slowly reduce and without treatment it will lead to AIDS