STDs and Microbial conditions Flashcards
What is a Commensal micro-organism?
A micro-organism that derives food or other benefits from another organism without hurting or helping it.
What is a Pathogen?
A micro-organism that can cause disease.
What is an infection?
The invasion of all or part of the body by a micro-organism.
If an infection has no symptoms what is it termed?
Sun-clinical
If an infection has symptoms what is it termed?
Clinical
What is a Sexually transmissible microbe?
A virus, bacteria or protozoan which can be spread by sexual contact:
- Commensal
- Pathogen
What is a Sexually transmitted infection (STI)?
An infection by a pathogen which is sexually transmissible and which is unlikely to be transmitted by non-sexual means:
- Neisseria gonorrhoeae
- HPV type 6
What is a Sexually transmitted disease (STD)?
A disorder of structure or function caused by a sexually transmitted pathogen:
- Pelvic inflammatory disease
- Genital warts
What are the Venereal diseases?
> Syphilis (Treponema pallidum pallidum)
> Gonorrhoea (Neisseria gonorrhoea)
> Chancroid (Haemophilus ducreyi)
Examples of bacterial “Sexually transmitted”
organisms in the UK?
Bacteria:
- Chlamydia trachomatis
- Klebsiella granulomatis
- Mycoplasma genitalium
Examples of viruses “Sexually transmitted”
organisms in the UK?
Viruses:
- HSV
- HIV
- HPV
- Molluscum contagiosum virus
Examples of parasites “Sexually transmitted”
organisms in the UK?
Parasites:
- Pthirus pubis
- Sarcoptes scabei
- Trichomonas vaginalis
Characteristics of STIs?
> Transmissible = Must treat sexual partners as well
> Often asymptomatic
> All are manageable but not all are curable
> Avoidable
What does sexually transmitted mean?
> Transmitted by sexual contact.
> But, there are a lot of different types of sexual contact.
Which STI require genital contact only?
Genital contact only:
- Pubic lice (Pthirus pubis)
- Scabies (Sarcoptes scabeii)
- Warts (human papilloma virus types 6 &11)
- Herpes (Herpes Simplex Virus types 1 & 2)
Why are STIs important?
1) They cause morbidity and can kill:
- Unpleasant symptoms
- Psychological issues
2) They’re a drain on resources:
- Infertility costs a lot
- HIV treatment is costly
- Time off work
3) They’re common
Ro=BcD
Ro = reproductive number (average number of infections produced) = likelihood of transmission
B = likelihood of transmission
c = rate of acquiring new partners
D = duration of infectivity
If Ro >1 then epidemic is sustained
If Ro <1 then epidemic reduces
If Ro is >1 what does this mean?
If Ro >1 then epidemic is sustained
If Ro is <1 what does this mean?
If Ro <1 then epidemic reduces
Which vaccination is recommended at ages 11 or 12, why?
HPV vaccination is recommended as it can drastically reduce the risk of future HPV infection and therefore cancer
NATSAL study (National survey of sexual attitudes and lifestyle) - what has it told us about sex and infection rates?
1) Increased numbers of partners/person
2) Increased concurrent partners
3) More people having anal sex
4) More men reporting sex with men (also increased condom usage).
Why my rates of STIs be increasing?
1) Change in the number of cases
2) Change in the number of diagnoses but no change in cases
Why my rates of STIs be increasing - number of cases?
1) Increased numbers of partners/person
2) Increased concurrent partners
3) More people having anal sex
4) More men reporting sex with men (also increased condom usage)
5) Dating apps
6) Alcohol consumption, “beer googles”
Why my rates of STIs be increasing - number of diagnosis?
1) More people asking for tests
2) More clinicians considering STIs and testing for them.
3) Better tests e.g. Nucleic acid amplification tests versus enzyme immunoassays for chlamydia
What is the idea around “Cores” and assortative mixing and STIs?
> Some people have sex with people like them (similar lifestyle – eg IDU, same ethnicity)
> Leads to high prevalence within a subpopulation (core) but limited spread through the wider community.
- Syphilis in people who exchange sex for drugs
- Lymphogranuloma venereum or HCV in HIV+ve MSM
What is the idea around “chains” and random mixing and STIs?
> Some ‘cores’ are very big – eg heterosexual men and women.
> Random mixing leads to lower prevalence but wider dissemination along ‘chains’.
> Most people have few sexual contacts over a given period of time and so chains are quite short
> If this was generalised, STI epidemics wouldn’t be sustained
What are the important aspect of a STI history?
1) A good history:
- Presenting complaint
- Direct questions
- History
- Past medical history
- Ginae history
2) Sexual history:
- When did you last have sexual contact?
- Casual contact vs ‘regular’ partner?
- How long were you going out with them for?
- Were they male or female?
- Asking about nature of sex act sometimes useful
anxiety about a specific incident
- If it’s going to alter where you swab from eg MSM
- Did you use condoms?
- Other contraception used
- Nationality of contact
3) Risk assessment (Man):
- Have you ever had sexual contact with a man?
- Have you ever injected drugs?
- Sexual contact with anyone who’s injected drugs?
- Someone from outside the UK? (clarify)
- Medical treatment outside UK? (clarify)
- Involvement with sex industry. (had sex with prostitute)
What are the important aspect of a STI history - Sexual history?
Sexual history:
- When did you last have sexual contact?
- Casual contact vs ‘regular’ partner?
- How long were you going out with them for?
- Were they male or female?
- Asking about nature of sex act sometimes useful
anxiety about a specific incident
- If it’s going to alter where you swab from eg MSM
- Did you use condoms?
- Other contraception used
- Nationality of contact
4) Partner notification (Contact tracing):
- Patient tells contacts “client referral”
- NHS tells contact “provider referral”
5) Offer/recommend further testing:
- Most STIs are risk factors for HIV acquisition and transmission.
- If someone has one STI (eg chlamydia) they could have another (eg HIV)
6) Health promotion:
- Condoms prevent transmission of some STIs -
Eg HIV, chlamydia, gonorrhoea
- Condoms aren’t very good at preventing transmission of other STIs
eg herpes and warts
- Oral sex carries risks too
> Not as great as vaginal or anal sex
> fellatio more than cunnilingus
- Alcohol and other drugs
What are the important aspect of a STI history - Risk assessment?
Risk assessment (Man):
- Have you ever had sexual contact with a man? - Have you ever injected drugs? - Sexual contact with anyone who’s injected drugs? - Someone from outside the UK? (clarify) - Medical treatment outside UK? (clarify) - Involvement with sex industry. (had sex with prostitute)
What are the important aspect of a STI history - Partner notification?
Partner notification (Contact tracing):
- Patient tells contacts “client referral”
- NHS tells contact “provider referral”
What are the important aspect of a STI history - Health promotion?
Health promotion:
1) Condoms prevent transmission of some STIs -
Eg HIV, chlamydia, gonorrhoea
2) Condoms aren’t very good at preventing transmission of other STIs
eg herpes and warts
3) Oral sex carries risks too
> Not as great as vaginal or anal sex
> fellatio more than cunnilingus
4) Alcohol and other drugs
What are the important aspect of a STI history - Offer/recommend further testing?
Offer/recommend further testing:
- Most STIs are risk factors for HIV acquisition and transmission.
- If someone has one STI (eg chlamydia) they could have another (eg HIV)
What is the difference between an STI and STD?
An STI is the infection, eg Human Papilloma Virus, whereas an STD is the disease(s) it causes; eg warts.
What causes Gonnorrhoea?
Neisseria gonorrhoeae
Symptoms of gonorrhoea in males?
1) 10% of males have no symptoms though might have clinical signs if examined.
2) Thick, profuse yellow discharge
3) Dysuria.
4) Rectal and pharyngeal infection often asymptomatic.
Symptoms of gonorrhoea in females?
1) >50% have no symptoms.
2) Vaginal discharge
3) Dysuria
4) Intermenstrual/post-coital bleeding
Complications of gonorrhoea?
Male = Epididymitis
Female:
- Pelvic inflammatory disease
- Bartholin’s abscess. [Gonococcal ophthalmia neonatorum.]
Both:
- Acute monoarthritis usually elbow or shoulder.
- Disseminated
Gonococcal Infection: skin lesions - pustular with halo. (both v rare).
What is the incubation period of Neisseria gonnorheoae?
Average 5 to 6 days. Range 2 days to 2 weeks (if get symptoms at all)
Number of new cases of gonnorheoa in grampian each year?
Approx 150 cases/yr in Grampian. Much less common than chlamydia. Most cases are in men, often in men who have sex with men (MSM).
How is gonnorhoea diagnosed?
1) Nucleic Acid Amplification Test (NAAT) on urine or swab from an exposed site – vagina, rectum, throat.
2) Gram stained smear from urethra/cervix/rectum in symptomatic people.
3) Culture of swab-obtained specimen from an exposed site using highly selective lysed blood agar in a
5% CO2 environment. Should be done for all confirmed cases to assess antibiotic sensitivity
Why is a culture performed in confirmed cases of Gonorrhoea?
Should be done for all confirmed cases of Gonorrhoea to assess antibiotic sensitivity.
How is Gonorrhoea treated?
1) Blind treatment with ceftriaxone 1g im.
2) Can also treat according to antibiotic sensitivities.
3) Follow up = Test of cure at 2 weeks and test of reinfection at 3 months
What cause Chlamydia?
Chlamydia trachomatis serovars D to K
[The rare Serovar L2b, which causes Lymphogranuloma venereum, usually gives symptoms of severe proctitis.]
Symptoms of Chlamydia ?
Male:
- > 70% asymptomatic
- Slight, watery discharge
- Dysuria
Females:
- 80% asymptomatic
- Vaginal discharge
- Intermentrual/post-coital bleeding
Both:
- Conjunctivitis
Complication od Chlamydia?
Male:
- Epididymitis
Women:
- Pelvic Inflammatory Disease and hence ectopic pregnancy, pelvic pain and infertility.
- Probably only ~1% of women who get chlamydia will develop a problem with their fertility
Both:
- Reactive arthritis/ Reiter’s syndrome - urethritis/ cervicitis + conjunctivitis + arthritis
How many new cases of Chlamydia in Grampian?
Approx 2000/yr in Grampian
Diagnosis of Chlamydia?
1) First void urine in men.
2) Self-taken or clinician-taken swab from cervix, urethra, rectum as appropriate.
3) All specimens tested using a NAAT
Treatment of Chlamydia?
1) Doxycycline 100mg bd 1 week
2) Azithromycin 1g po once if pregnant
3) Test for reinfection at 3-12 months. Earlier test of cure not needed unless symptoms persist.
Cause of Herpes?
Herpes Simplex Virus types 1 and 2 (HSV)
Symptoms of Herpes?
1) 80% have no symptoms.
2) The rest have recurring symptoms – monthly, annually:
- Burning/itching then blistering then tender ulceration.
- Tender inguinal lymphadenopathy.
- Flu-like symptoms.
- Dysuria,
- Neuralgic pain in back, pelvis and legs,
Complications of Herpes?
1) Autonomic neuropathy (urinary retention)
2) Neonatal infection
3) Secondary infection.
Incubation period of Herpes?
About 5 days to months. Some people never report symptoms
Epidemiology of Herpes?
Very common ~ 15-20% of UK population has it. Both strains equally common in genital infection. Roughly equal between sexes. HSV2 is important co-factor for HIV transmission.
Diagnosis of Herpes?
1) Clinical impression.
2) Swab from lesion tested using PCR
Treatment of Herpes?
1) Primary Outbreak = Aciclovir: various regimens – eg 400mg tds for 5 days Lidocaine ointment
2) Infrequent recurrences = Lidocaine ointment. Aciclovir 1.2g once daily until symptoms gone (1-3 days)
3) Frequent recurrences = Aciclovir 400bd long-term as suppression.
What is Trichomoniasis causes by?
Trichomonas vaginalis
Symptoms of Trichomoniasis?
Men: usually asymptomatic
Women:
- 10-30% asymptomatic
- Profuse thin vaginal discharge - greenish, frothy and foul smelling.
- Vulvitis.
Epidemiology of Trichomoniasis?
Uncommon, approx 100/yr in Grampian.
More common in middle aged women than some other STIs are.
Complications of Trichomoniasis?
1) Miscarriage
2) Preterm labour
Diagnosis of Trichomoniasis?
1) PCR on a vaginal swab.
2) NB not validated on urine yet so no test for men.
3) Point of Care - Microscopy of wet preparation of vaginal discharge.
Treatment of Trichomoniasis?
Metronidazole 400mg po bd for 5 days or 2g single dose.
What are anogenital warts caused by?
Human Papilloma Virus types 6 and 11 (and occasionally type 1). (NB different strains from those that cause cervical cancer.
Symptoms of anogenital warts?
Lumps with a surface texture of a small cauliflower.
Occasionally itching or bleeding especially if perianal or intraurethral.
Epidemiology of anogenital warts?
1) >90% of UK population have a genital HPV infection at some point in their life.
2) Only about 20% of those infected with a wart-causing strain of human papilloma virus get warts.
3) A drop in cases is anticipated in response to quadrivalent HPV vaccine
Complications of anogenital warts?
1) None common.
2) Neonatal laryngeal papillomatosis.
Diagnosis of anogenital warts?
Appearance.
Biopsy if unusual – to exclude intraepithelial neoplasia, but this is rarely needed
Treatment of anogenital warts?
1) Podophyllotoxin (brands warticon and condyline), imiquimod (brand Aldara).
Both home treatments.
2) Others – cryotherapy
3) Bulky warts – diathermy, scissor removal.
What is the cause of Syphilis?
Treponema pallidum subspecies pallidum
Symptoms and signs of Syphilis?
1) Diverse – “He who knows Syphilis knows medicine” – Osler.
2) Often entirely asymptomatic or mild symptoms which go unreported.
3) Primary = Local ulcer
4) Secondary = Rash, mucosal ulceration, neuro symptoms, patchy alopecia, other symptoms.
5) Early latent = No symptoms but <2years since caught.
6) Late latent = No symptoms but >2 years since caught.
7) Tertiary = Neurological, cardiovascular or gummatous – skin lesions, (all v rare)
Epidemiology of Syphilis?
Approx 20 cases/yr in Grampian. >90% of cases in Scotland are in men who’ve had sex with men
Complications of Syphilis?
1) Neurosyphilis – cranial nerve palsies are commonest
2) Cardiac or aortal involvement.
3) Congenital syphilis (extremely rare in Scotland).
What is incubation period for Syphilis?
1) 9 to 90 days until appearance of chancre.
2) But can be asymptomatic.
What is the diagnosis of Syphilis?
1) Clinical signs
2) Serology for TP IgGEIA, TPPA and RPR
2) PCR on sample from an ulcer
Treatment of Syphilis?
1) Early (<2 yrs and no neurological involvement):
- Benzathine penicillin 2.4 MU im once
Or
- Doxycycline 100mg bd po 2 weeks
2) Late (>2 years) and no neurological involvement:
- Benzathine penicillin 2.4MU im weekly for 3 doses
- Doxycycline 100mg bd po 28 days
What is vulvovaginal candidosis?
Also known as Thrush
What causes vulvovaginal candidosis?
> 90% Candida albicans
> Can be Candida glabrata et al
What is the source for Candida in vulvovaginal candidosis?
Usually acquired from bowel
What leads to symptoms with Candida?
Changes in the host’s environment trigger pathogenicity
What are the symptoms of thrush (Vulvovaginal cadidosis)?
> Itch
> Discharge - classically thick, ‘cottage cheese’ but often just a report of increased amount.
What increases the risk of vulvovaginal cadidosis?
> Diabetes
> Oral steroids
> Immune suppression including HIV
> Pregnancy
> Reproductive age group
( oestrogen…glycogen = food for yeast)
How to diagnose vulvovaginal candosis?
1) Characteristic history
2) Examination findings:
- Fissuring
- Erythema with satellite lesions
- Characteristic discharge
3) Investigations:
- Gram stained preparation = Low sensitivity – might look at an unrepresentative patch
- Culture – eg Sabouraud’s medium = Low specificity – yeast are often commensal
How to treat vulvovaginal candosis?
1) Azole antifungals:
> Clotrimazole 500mg PV once (Plus Clotrimazole HC if vulvitis)
> Fluconazole 150mg PO once
2) Other management:
> Avoid irritants
> Treat dermatitis
What is the most common cause of abnormal vaginal discharge?
Bacterial vaginal discharge = 10-40% of women at any time
What are the symptoms of bacterial vaginosis?
> Asymptomatic in 50%
Watery grey/yellow ‘fishy’ discharge
May be worse after period/sex
Sometimes sore/itch from dampness
What leads to the symptoms of bacterial vaginosis?
Imbalance of bacteria rather than infection
Biofilm problem with bacterial vaginosis?
1) Increased gardnerella / ureaplasma / mycoplasma /anaerobes
2) Reduced lactobacilli
3) Sexually transmissibility controversial
4) Associated with vitamin D deficiency but just in black women
Complications of bacterial vaginosis?
1) Associated with endometritis if uterine instrumentation / delivery
2) Associated with premature labour
3) Increases risk of HIV acquisition
How is bacterial vaginosis diagnosed?
1) Characteristic history
2) Examination findings
- Thin, homogenous discharge
3) Gram stained smear of vaginal discharge
Treatment of bacterial vaginosis?
1) Metronidazole:
- Oral (Avoid ethanol)
- Vaginal gel
2) Clindamycin:
- Vaginal
What is balanitis?
Balanitis is swelling of the foreskin, or head of the penis
What is posthitis?
Posthitis is the inflammation of the foreskin (prepuce) of the human penis
What is Zoon’s balanitis?
Plasma cell balanitis
Chronic inflammation secondary to overgrowth of commensal organisms plus ‘foreskin malfunction’.
Causes of impetigo?
1) Staph aureus
2) Strep pyogenes
What is Erysipelas?
It is an infection of the upper dermis and superficial lymphatics, usually caused by beta-hemolytic group A Streptococcus bacteria on scratches or otherwise infected areas
What can cause a Dermatophyte infection?
1) Trichophyton rubrum
2) Tinea crisis = Athlete’s groin
What can cause Erythrasma?
Corynebacterium minutissimum
What is Erythrasma?
Erythrasma is a chronic superficial infection that causes brown, scaly skin patches of the intertriginous areas of skin caused by Corynebacterium minutissimum
What is dermatoses?
Any noninflammatory disorder of the skin.
> Lichenoid dermatosis any skin disorder characterized by thickening and hardening of the skin.
> Precancerous dermatosis any skin condition in which the lesions, such as warts, nevi, or other excrescences, are likely to undergo malignant degeneration.
What are Fox-Fordyce spots?
Fordyce spots are small raised bumps that appear on the shaft of the penis, the labia, scrotum, or next to the lips.
They can be pale red, yellow-white, or skin-colored
Fordyce spots are not a sexually transmitted infection.
They are not infectious.
They are not a health concern
What are vulval papillomatosis?
Vestibular papillomatosis is characterized by small, shiny, skin-colored growths on a woman’s vulva, which is the outer part of the vagina (Labia minora).
No health risk
What are coronal papillae (Penile pearly papules)?
Corneal papillae are small protuberances that may form on the ridge of the glans of the human penis.
What are Tyson’s glands?
> Prominent Sebaceous Glands of Penis are small, raised papules, multiple in number that occurs on the shaft of the penis. They can vary in color from white to red and are usually 2-3 mm (each) in size
> These papules are actually sebaceous glands that have increased in size. Prominent Sebaceous Glands of Penis are non-infectious and are not sexually transmitted
