MICROBIOLOGY Flashcards
What are the common microbial causes of cervicitis?
- Chlamydia trachomatis
- Neisseria Gonorrhoea
- HSV
- Trichomonas vaginalis (protozoa)
- Anaerobes
Mark also indicates that Mycoplasma Genitalium can cause this, but it isn’t as common (STI Lecture 2).
1-3 most common causes. Remainder not as common.
Describe the common clinical presentation of cervicitis, and include associated symptoms
- Discharge (usually mucopurulent from endocervix)
- Inflamed & oedematous ectropion
Commonly associated with:
- Co-exiting urethral infection
- History of dysuria
Where do you collect specimens to diagnose cervicitis, and what technique do you use to diagnose it?
Always take a sample of the discharge
Swab high vagina (next to ectropion on cervix), endocervical) and a first pass urine.
Analyse all using PCR are most organisims don’t culture.
What are the common microbial causes of urethritis?
Gonococcus
Chlamydia trachomatis
The following are gaining importance: Ureaplasma urealyticum Mycoplasma hominis Trichomonis vaginalis (protozoa) HSV
Describe the common clinical presentation of urethritis, and include associated symptoms
Urethral inflammation
In males also meatal inflammation
Dysuria
Discharge
What are the differential diagnosis for someone presenting with urethral discharge & dysuria?
Urethritis, Cystitis or ureter infection
What are the important aspects of clinical history and specimen collection for a patient suspected of having gonococcal urethritis?
Need to take a good history of exposure - eg oral/anal sex as often these areas can also be infected, not just urethra, but are asymptomatic.
Swab urethra, +/- anorectal/pharyngeal areas depending on history of risky behaviour.
What is pelvic inflammatory disease (PID)?
Inflammation & infection of the upper genital tract in females, typically including: Endometrium Ovaries Fallopian tubes Surrounding structures
What are clinical signs & symptoms of PID?
Adnexal tenderness Cervical motion tenderness Lower abdomen discomfort/tenderness/rebound/guarding Vaginal discharge Bleeding Dyspareunia (pain during intercourse)
What are the complications of PID?
20% infertility
20% chronic pelvic pain
10% ectopic pregnancy
Increase the chance/risk of complication, the more times you have PID.
Common causative agents/mechanisms by which PID is acquired?
SEXUAL ACQUISITION Chlamydia trachomatis (+/- gonorrhoea). Usually polymicrobial which makes treatment protracted and complex.
NON-SEXUAL ACQUISITION
Mechanical disruption to cervix (eg insertion of IUCD, delivery, surgery, pregnancy, termination) can increase risk, as these can disturb normal flora of vagina and increase susceptibility.
What is the characteristic appearance of Gonorrhoea under the light microscope?
Gram negative diplococci within the neutrophil cytoplasm.
What is the characteristic appearance of Gonorrhoea under the light microscope?
Gram negative diplococci within the neutrophil cytoplasm.
On which media is Gonorrhoea grown, and why?
Gonorrhoea is very fastitidious (difficult to culture) so is often grown on chocolate agar or Thayer-Martin agar (enriched media).
What is Thayer-Martin agar/media, and what is it used for? Why?
It is chocolate agar + antibiotics and used to culture Gonorrhoea (which is fastitidious). It is used to suppress ‘normal’ flora overgrowth, so that if gonorrhoea is present it will grow preferentially.
Is Gonorrhoea more common in males or females? What percentage of each, which infected, will be symptomatic?
Gonorrhoea occurs equally in males and females.
50% of females are symptomatic, while almost all males are symptomatic.
Carrier state does depend on anatomical location of infection - anorectal area and pharyngeal infections are normally asymptomatic.
What are the risk factors for getting gonorrhoea
Low socio-economic status Urban area Unmarried MSM Ethinicity Drug use Prostitution Hx of STDs Hormonal contraception Unprotected intercourse (>80% chance for single exposure for a female, 20% chance for a single exposure for a male, 80% for multiple exposures for male) --> much higher transmission rate from penis --> vagina
What are the common clinical manifestations of Gonorrhoea in males?
Urethritis (with mucopurulent discharge 90-95%)
Dysuria
Ascending infection (10%) - includes epididymitis (one teste inflamed), prostatitis, urethral stricture or periurethral abscess (common).
5% may be asymptomatic.
How long is Gonorrhoeal incubation in males before clinical manifestation? And how long in females?
Males: 2-7 days after exposure
Females: 8-10 days after exposure
What are the common clinical manifestations of Gonorrhoea in females?
Urethritis (70-90%)
Cervicitis (25-68%)
Bartholins Glands infected (30%) normally these aren’t visible, but when infected they are.
Ascending infection (10-20%) including PID associated with salpingitis, endometritus, tubo-ovarian abscess.
Abnormal intra-menstrual bleeds
Abdominal/pelvic pain
50% asymptomatic
Clinical manifestations of Gonorrhoea (not just urogenitcal tract infections)
- Urogenital tract infections
- Gonococcaemia (septicaemia)
- Disseminated infections of skin & joints (males more than females, 1-3%). Includes the pustular rash which necrosis, suppurative arthritis etc.
- Pharyngitis (asymptomatic often)
- Purulent conjunctivitis of the newborn
Many other syndromes.
How is Gonorrhoea diagnosed?
First pass urine & swabs of site of infection (ensure Rayon or Dacron swabs used). Cultured on Thayer-Martin, PCR used to identify.
Public health implications of Gonorrhoea?
Reportable STD.
Must do contact tracting.
Follow up testing to ensure success of treatment.
Chlamydia is an obligate intracellular organism and has a biphasic life cycle. Explain what this means.
Obligate intracellular - can’t replicate/survive without using the host energy/ATP source.
Elementary body - the extracellular form which infects eukaryotic cells.
Reticular body - the intracellular form which replicates.
Which Chlamydia trachomatis serovars are responsible for urogenital tract disease?
Trachoma serovars D-K (A-C responsible for trachoma)
Which Chlamydia trachomatis serovars are responsible for urogenital tract disease?
Trachoma serovars D-K (A-C responsible for trachoma)
In which population is chlamydia most prevalent?
Females aged 15-25 (greater incidence in females to males)
Is Chlamydia mostly symptomatic or asymptomatic in females?
Asymptomatic (80%).
Is Chlamydia mostly symptomatic or asymptomatic in females?
Asymptomatic (80%).
Chlamydia associated cervicitis (females) and urethritis (Both) is associated with discharge. Describe it.
Mucupurulent, usually thinner and less copious than gonorrhoea. Yellow/green in colour usually.
Chlamydia associated cervicitis (females) and urethritis (Both) is associated with discharge. Describe it.
Mucupurulent, usually thinner and less copius than gonorrhoea. Yellow/green in colour usually.
Lymphgranuloma venereum is a manifestation of chlamydia. Describe the course of presentation.
STAGE 1: 1-4 weeks post infection. Painless lesion (papule or ulcer) develops on site of infection eg penis, scrotum, vagina etc. Can be confused wtih Syphilis.
STAGE 2: 1-4 weeks post infection. Infection travels to the lymph nodes. Lymph nodes become infected and inflamed/swollen. Very painful. Can give rise to fluctuant buboes that enlarge and rupture.
Systemic symptons include:
Fever Chills Headache arthralgia myalgia
How to diagnose Chlamydia?
PCR
