STIs: bacteria Flashcards
Discuss the spectrum of STI presentations
- Asymptomatic infection
- Lower genital tract symptoms (vaginal/urethral discharge)
- Upper genital tract symptoms (pelvic inflammatory disease/epididymoorchitis/infertility)
- Warts (cervical cancer)
- Human papilloma virus – becoming less common
- Ulcers
- Herpes simplex viruses 1/2 - extremely common
- Syphilis (Treponema pallidum) uncommon, but more prevalent in MSM and Indigenous populations
- Other rare causes include chancroid, donovanosis, Mpox, and non-infectious causes
- Blood borne viruses e.g. HIV, Hep B, CMV
Describe the epidemiology and clinical features of Trichomonas vaginalis
- protozoan
- more common in females
- infects vagina and urethra
- often asymptomatic (70%)
- mild irritation to severe inflammation
- preterm labour and LBW
- treat with metronidazole or tinidazole
- less common than Chlamydia and gonorrhoeae in general population
- much more common in Indigenous population, more common in females, most common in 15-25 year age group, however similar incidence between 25-40 years old
Describe the diagnosis and treatment of Trichomonas vaginalis
- treat with metronidazole or tinidazole
Discuss the epidemiology and clinical features of Chlamydia trachomatis
Chlamydia
- More common in females 15-30 years
- More common in indigenous populations
- More common in Northern Territory
- Commonest STI with a gradual increase in incidence
- Obligate intracellular bacteria i.e. Chlamydia
- require host products for growth
- can only reproduce when inside the eukaryotic cell host
- typically invade epithelial or endothelial cells forcibly or by inducing changes in cytoskeleton i.e. to actin or microtubules so that bacteria are engulfed (receptor-mediated endocytosis)
- cannot culture on inert media i.e. normal agar, and need living cells, like viruses
Chlamydia Species
- Obligate intracellular pathogens causing various diseases:
- sexually transmitted diseases
- Chlamydia trachomatis, particularly serovars D-K: cervicitis, ureteritis, conjunctivitis in neonates
- serovars L1.2.3 - lymphogranuloma venereum (uncommon) - swollen lymph nodes
- trachoma (severe and chronic form of conjunctivitis)
- serovars A-C
- ‘atypical’ pneumonia
- Chlamydophilia pneumoniae
- Chlamydia psittaci (psittacosis and parrot disease)
Chlamydia is Biphasic
- Elementary bodies (extracellular, infectious form), survives outside cell, metabolically inert and do not divide. Taken up by receptor-mediated endocytosis involving microfilament rearrangement
- Reticulate bodies (intracellular form): metabolically active and replicates within the endoso
Discuss the diagnosis and treatment of Chlamydia trachomatis
Chlamydia
- Not able to Gram stain
- Cannot grow on inert media (e.g., agar)
- Cell culture ie. in living cells was the traditional method
- Molecular diagnosis (PCR) is now the routine method
- Azithromycin or doxycycline is the treatment of choice
Discuss the epidemiology and clinical features of Neisseria gonorrhoeae
Gonococcal Infections
- More common in men
- Most common in 20-30 year age group in men
- Most common in 15-25 year age group in women
- Much more common in indigenous populations
- Highest rates in indigenous and non-indigenous populations in Northern Territory
- Increasing numbers and incidence in ACT & nationally
Neisseria gonorrhoeae
- Gram-negative diplococci, facultative intracellular bacteria
- Mechanism of entry and virulence factors
- Fimbriae or pili attachment
- Antigenic variation of pili for immune system evasion
- helps to evade immune system
- difficulties in development of a vaccine strategy: if directed against entry, is impossible
- people remain susceptibility to reinfection
Discuss the diagnosis and treatment of Neisseria gonorrhoeae
Gonorrhoea
- Fastidious bacterium
- Special growth factors required
- Slower grower
- Culture and PCR are used for diagnosis, PCR is more sensitive and is the choice for asymptomatic screening, as the cervix/vagina is not sterile, require media which inhibits growth of other bacteria and allows growth of gonococcus
- Antibiotic susceptibilities testing is crucial because of drug resistance
- Treat with ceftriaxone via IM single dose
Describe the structure of Chlamydia and its impact on diagnosis and treatment
Chlamydia Structure
- outer membrane stabilised by
- major outer membrane proteins or MOMPs, differences determine serovars
- CRP or cysteine rich proteins, which also forms the P layer
- No peptidoglycan layer
List the genital infections caused by both chlamydia and gonorrhoea in males and females
- Urethritis (typically symptomatic in men)
- Epididymoorchitis
- Prostatitis
- Proctitis
- Pharyngitis
- Cervicitis (typically asymptomatic in women)
- Endometritis
- Salpingitis
- Oophoritis
- Tubo-ovarian abscess
- Peritonitis
Describe PID and neonatal infections
Pelvic Inflammatory Disease (PID)
- Infection of the upper genital tract by these STIs causes extensive scarring and infertility, and increased risk of ectopic pregnancy
Neonatal Infection
- Gonococcal ophthalmia neonatorum
Describe extragenital manifestations of chlamydia and gonorrhoea
- Other extragenital manifestations in both Chlamydia and Gonorrhoeae
- chlamydia:
- reactive arthritis/Reiter’s syndrome : urethritis, conjunctivitis, perihepatitis (Fitz Hugh Curtis syndrome)
- gonorrhoeae:
- disseminated infection e.g. endocarditis
- septic arthritis
- reactive arthritis
- conjunctivitis
- perihepatitis (Fitz Hu
- chlamydia:
Describe reasons for STI testing in females
- vulvovaginitis due to S. aureus, Groups A and B Strep, S. aureus, which are part of normal flora. Diagnostic test is vulvovaginal swab MCS
- vaginal discharge - vaginitis
- Candida sp., bacterial vaginosis, Group B Strep- all part of normal flora. Diagnostic test is vaginal swab MCS
- Trichomonas vaginalis, which is NOT part of normal flora. Test with vaginal swab microscopy and PCR
- vaginal discharge - cervicitis
- e.g. due to Chlamydia trachomatis and Neisseria gonorrheae which are NOT part of normal flora. Diagnostic test is cervical swab MCS and CT/NG PCR
- Pelvic inflammatory disease due to Chlamydia and Neisseria, which are NOT part of the normal flora, and mixed flora e.g. coliforms, anaerobes and Strpetococci, which are part of normal flora. Test for all with cervical swab MCS and CT/NG PCR
- Asymptomatic STI screen due to Chlamydia and Neisseria (high risk). Both are NOT part of normal flora, and are tested with urine/vaginal swab and CT/NG PCR, AND throat/rectal swab CT/NG PCR
Describe reasons for testing in males
- balanitis due to mixed flora (coliforms, anaerobes, Stretococci, S. aureus, Candida sp.). Part of normal flora. Tested with skin swab MCS
- Urethral discharge, due to Chlamydia, Neisseria, Trichomonas. NOT part of normal flora. Tested with urethral swab MCS + CT/NG/Trichomonas PCR
- Epididymoorchitis due to Chlamydia and Neisseria which are NOT part of the normal flora, and E.coli which IS. Test for exogenous bacteria with urine MCS and PCR (CT/NG), and for E. coli with urine MCS
- Asymptomatic STI screen, for Chlamydia and Neisseria (in high risk). Both organisms are NOT part of the normal flora, and are tested for with urine CT/NG PCR, throat and rectal swab, CT/NG PCR
- Genital ulcers in both male and female due to several exogenous organisms including HSV, syphilis, donovanosis, H. ducreyi, Mpox, and other dermatological and systemic conditions. Tested for viral swab PCR, dark field microscopy, histology and specialised culture
