sexual health Flashcards
define commensal micro-organism
micro-organism derives food or other benefits from another organism without hurting or helping it
define pathogen
micro-organism that can cause disease
define infection
the invasion of all or part of the body by a micro-organism
what is the difference between a clinical and sub-clinical infection?
clinical = symptoms subclinical = no symptoms
define sexually transmissible organism
a virus, bacteria, protozoan, insect or arthropod which can be spread by sexual contact
- can be commensal or pathogen
define sexually transmitted infection
infection by a pathogen which is sexually transmissible and which is unlikely to be transmitted by non-sexual means
- neisseria gonorrhoeae
- HPV type 6
define sexually transmitted disease
disorder of structure or function caused by a sexually transmitted pathogen
- pelvic inflammatory disease
- genital warts
give examples of venereal diseases and their causative agent.
- syphilis (Treponema pallidum pallidum)
- gonorrhoea (Neisseria gonorhoeae)
- chancroid (Haemophilus ducreyi)
give examples of other sexually transmitted organisms in the UK.
bacteria
- chlamydia trachomatis
- klebsiella granulomatis
- mycoplasma genitalium
viruses
- HSV
- HIV
- HPV
- molluscum contagiosum virus
parasites
- pthirus pubis
- sarcoptes scabei
- trichomonas vaginalis
give examples of sexual contact
- group sex
- anal sex
- vaginal sex
- oral sex
- touching someone else’s genitals with yours
- mutual masturbation
what conditions can be transmitted through genital contact alone?
- pubic lice (Pthirus pubis)
- scabies (Sarcoptes scabeii)
- warts (human papilloma virus types 6 &11)
- herpes (Herpes Simplex Virus types 1 & 2)
What condition is often transmitted through group sex?
Hepatitis C
Why are STIs important?
- cause morbidity and mortality
- drain on resources
- they’re common
what symptoms can STIs present with?
- ulceration
- lumps
- genital discharge
- non genital discharge
- rashes
- systemic symptoms: fever, rash, lymphadenopathy, malaise, infertility
What are the possible complications of STIs?
- infertility (chlamydia)
- cancer
- adverse pregnancy outcomes
why do diagnoses of STIs change over time
a difference in the number of cases
- transmissibility
- rate of acquiring new partners
change in the number of diagnoses but no change in cases
- greater awareness of STI = more testing
- better tests
- more clinicians considering STIs
how can we tell if there is change in the number of cases of STIs?
Ro = bcd
Ro (reproductive number) = average number of infections produced
b = likelihood of transmission per encounter
c = rate of acquiring new partners
d = duration of infectivity
Ro = bcd
Ro >1 then epidemic is sustained
Ro <1 then epidemic reduced
what testing methods are used?
- nucleic acid amplification testing
- enzyme immunoassays for chlamydia
modelling and mapping the spread of STIs
cores and assortative mixing
- some people have sex with people like them = high prevalence within a subpopulation
chains and random mixing
- random mixing = lower prevalence but wider dissemination along ‘chains’
what are the principles of management for someone presenting with symptoms suggestive of STI?
good history
partner notification: client referral, provider referral
HIV testing
health promotion: condoms, vaccination, hazardous drug use
genital symptoms
- lumps and swellings
- discharge from an orifice
- pain
- rashes
- cuts, sores, ulcers
- itching
- change in appearance
cause of genital symptoms
- STD
- microbial problem
- non-microbial problem
what microbial conditions of the genitals are not regarded as STDs?
- vulvovaginal candidosis
- bacterial vaginosis
- balanoposthitis – anaerobic/candidal
- tinea cruris
- erythrasma
- infected sebaceous glands
- impetigo
- cellulitis
vulvovaginal candidosis
- 90% Candida albicans (can be C. glabrata et al)
- usually acquired from bowel
- asymptomatic, if symptomatic: thrush, itch, discharge
- risk factors: diabetes, oral steroids, immune suppression, pregnancy, reproductive age group
- diagnosis: gram stained preparation, culture
- treatment: antifungal azoles (clotrimazole, fluconazole)
bacterial vaginosis
abnormal vaginal discharge: watery grey/ yellow ‘fishy’ discharge
sore/itch from dampness, worse after period / sex
diagnosis: pH, gram stained smear
treatment: antibiotics (metronidazole, clindamycin), probiotics,
describe balanitis
- inflammation of the glans penis
- blotchy red appearance/ discolouration of the glans penis
describe zoon’s balanitis
chronic inflammation secondary to overgrowth of commensal organisms plus ‘foreskin malfunction’.
describe posthitis
Inflammation of the foreskin
what are usually the causative organisms of impetigo?
- staph aureus
- strep pyogenes
what is usually the causative agent of erysipelas?
strep pyogenes
what is tinea cruris?
dermatophytes infection known as athlete’s groin
what is usually the causative agent of erythrasma?
Corynebacterium minutissimum
what non-microbial symptoms of the genitals may people present with?
- perceived problems: discharge, dysuria, rashes, skin lumps
- dermatoses
- structural abnormality (congenital and acquired)
what are Fox-Fordyce spots?
appearance of normal sebaceous glands through stretched skin
