HIV and STIs Flashcards
What is the most common diagnosed STI in the UK?
Chlamydia
What has led to a decrease in the prevelance of chlamydia in young people?
Increased testing
How are STIs spread?
Mucous membrane contact or exchange of bodily fluids
What is meant by the fact that pathogens causing STIs are often fastidious organisms?
Don’t survive for long when isolated from a membrane or sight of infection
In what 4 ways can STIs be passed from mother to baby - ie vertical transmission?
1) In utero - transplacental
2) Peri natal - passage through infected birth canal
3) Eye mucous membrane - conjunctivitis
4) Present in breast milk
Risk of transmission/acquisition is related to which 2 factors?
1) Acquisition is primarily related to number of sexual partners
2) Increased risk with no use of barrier contraception
(Also patients with one STD is more likely to have other STDs)
What process is important in reducing transmission of STIs?
Contact tracing
Neisseria gonorrhoea is also known as what?
Gonococcus
What kind of bacteria is Neisseria gonorrhoea?
Gram negative coccus - diplococcus - ie sits in pairs
What are the 2 other common Neisseria species?
1) Neisseria meningitides
2) Non pathogenic Neisseria species - normal commensal flora of the throat and genital tract
How does Neisseria gonorrhoea multiply?
Intracellularly
Neutrophils engulph the organism in phagocytosis but are unable to kill the organism and it replicates within the neutrophils
What adaption does Neisseria meningitidis have to increase its ability to attach to mucosal epithelial cells, and what epithelium does it primarily infect?
Pilli on the cell surface (piliated cells more virulent)
Primarily infects columnar/ cuboidal epithelium
How many layers is the ‘cell envelope’ of Neisseria gonorrhoea made up of?
3 layers as a gram negative bacteria
Has a thin peptidoglycan wall but an outer membrane
What are the 3 most common bodily sights of infection of Neisseria gonorrhoea?
1) GU tract
2) Rectum
3) Oropharynx
How long is the intubation period of Neisseria gonorrhoea and what percentage of women are asymptomatic?
2-5 days incubation period
60% of women are asymptomatic
What are the 2 main symptoms of gonorrhoea?
1) Urethral discharge
2) Dysuria (painful urination)
What are the 7 local complications of gonorrhoea?
1) Epididymitis
2) Prostatitis
3) Barthonilitis
4) Salpingitis (inflammation of uterine tubes)
5) PID (pelvic inflammatory disease)
6) Peritonitis
7) Fitz-Hugh-Curtis syndrome (perihepatitis)
People who suffer Fitz-Hugh-Curtis syndrome (perihepatitis) as a complication of gonorrhoea are usually co infected with what organism?
Chlamydia trachomatis
What are the 4 components of disseminated gonococcal infection (in what percentage of people does it occur)?
1) Bacteraemia
2) Arthritis
3) Dermatitis
4) Meningitis
Occurs in 0.5-3% of the untreated
Gonorrhoea in pregnancy can lead to which 2 things?
1) Spontaneous abortion
2) Premature labour
Gonorrhoea can cause what 2 conditions in the neonate?
1) Ophthalmia neonatorum
2) Acute purulent conjunctivitis (
What are the 3 steps in diagnosis of gonorrhoea?
1) Microscopy - urethral swab (male)
2) Culture - endocervical, urethral swab
3) Nucleic acid amplification test (PCR) - urine or vaginal swab
Neisseria gonorrhoea has widespread resistance against which antimicrobial?
Tetracycline
What are the 3 types of antibiotics used to treat gonorrhoea?
1) Beta-lactams (benzylpenicillin, amoxicillin)
2) Cephalosporins (cefixime -PO, ceftriaxone IV or IM)
3) Fluoroquinolones - (ciprofloxacin)
What is the emerging problem with treating gonorrhoea?
Neisseria gonorrhoea is becoming increasingly resistant to many Abx - reaching a point where there are untreatable strains of gonorrhoea
Non gonococcal urethritis (NGU) is caused by what 2 organisms?
1) Chlamydia trachomatis types D-K
2) Ureaplasma urealyticum (mycoplasma genitalium)
What is the incubation period of the organisms causing non-gonococcal urethritis?
1-2 weeks
How is a diagnosis of non-gonococcal urethritis made?
NAAT for chlamydia (nucleic acid amplification test)
What are the 2 possible antibiotic treatments for non gonococcal urethritis?
1) Doxycycline
2) Macrolide; erythro-/ azithro-mycin
What kind of pathogen is chlamydia trachomatis?
Obligate intracellular pathogen
What is unique about the lifecycle of chlamydia trachomatis?
Extracellular infectious form: elementary body
Intracellular replicative form: reticulate body
What are the 4 target cells/tissues of chlamydia trachomatis?
1) Squamocolumnar epithelial cells of endocervix/ upper genital tract in females
2) Conjunctiva in both males and females
3) Urethra in both males and females
4) Rectum in both males and females
What is the additional target cells of infection of chlamydia trachomatis in infants?
Respiratory epithelium
Chlamydia is often asymptomatic (more so in females than males) - what are the 3 possible symptoms?
1) Urethritis - less purulent discharge than gonococcal
2) Cervicitis - mucopurulent
3) May have dysuria/ frequency
Chlamydia is a cause of ‘acute urethral syndrome’, what is acute urethral syndrome?
Sterile pyuria (see white cells but cant culture bacteria)on standard analysis
What are the 5 complications of chalmydia?
1) PID
2) Perihepatitis
3) Epididymitis
4) Conjunctivitis
5) Reiter’s syndrome
PID is a complications of chlamydia infection, how can this lead to infertility?
Tubal infertility - get inflammation of fallopian tubes
Can also lead to ectopic pregnancy and chronic pain
Reiter’s syndrome is a complication of chlamydia, what is Reiter’s syndrome?
1) Arthritis
2) Conjunctivitis
3) Urethritis
4) Skin lesions
What are the 2 main complications of chlamydia in the neonate/ infant?
1) Conjunctivitis
2) Infant pneumonia
What 4 procedures involved in diagnosis of chlamydia?
1) Histology - inculsion bodies
2) Cell culture
3) NAAT (nucleic acid amplification test)
4) Serology - although this has limited value in most oculogenital infections
The normal treatment for chlamydia if one of which 2 antibiotics?
1) Azithromycin
2) Doxycyline
What antibiotic is used to treat chlamydia causing conjunctivitis/ pneumonia in paediatric patients?
Erythromycin
By what process is PID usually diagnosed?
Laparoscopy
What are the 2 low risk HPVs and what do they cause?
Types 6 and 11 - cause genital warts
What are the 2 high risk HPVs and what do they cause?
Types 16 and 18 - cause cervical carcinomas
What are condylomata accuminata?
The genital warts caused by HSV
By what 6 ways can condylomata accuminata be removed?
1) Burn
2) Freeze
3) Cut
4) Imiquimod
5) Podophyllin, salicyclic acid, trichloracetic acid
6) Liquid nitrogen
Genital herpes are caused by what pathogen?
Herpes simplex virus types 1 and 2
What kind of virus is HSV?
Double stranded DNA virus
Which type of herpes simplex virus is more common in women than men?
HSV-2
What are the 6 symptoms of primary genital herpes?
1) Pain
2) Itching
3) Dysuria
4) Vaginal/ urethral discharge
5) Bilateral vesicles/ ulcers
6) Accompanied by constitutional symptoms
HSV can remain latent in sacral nerve ganglia, reactivation of HSV can cause what 3 symptoms?
1) Local trauma
2) Menstruation
3) Stress
What are the 3 steps in diagnosis of HSV?
1) Clinical
2) PCR
3) Histology
What is the treatment for HSV, what should be considered if frequent recurrence?
Treatment = acyclovir
Should consider suppression if frequent recurrence
What are the 5 complications of genital herpes?
1) Dissemination
2) Meningitis
3) Encephalitis
4) Sacral nerve paraesthesia
4) Urinary retention
Syphilis is caused by which pathogen?
Treponema pallidum (A spirochaete)
What shape is treponema pallidum (causes syphilis)?
Slender, helical, tightly coiled
What is the pathogenesis of syphilis?
1) Treponema pallidum penetrates intact mucous membranes or via abraded skin
2) Disseminates within days via lymphatics or bloodstream
3) Get subsequent clinical symptoms and signs
What is the characteristic histology of syphilis?
Obliterative endarteritis
What does primary syphilis infections result in (after median incubating time of 21 days)?
Chancre - painless indurated lesion at the sight of inocultation which will heal spontaneously within 3-6 weeks
The secondary phase of syphilis infection occurs 2-8 weeks post onset of chancre, what are the 8 symptoms?
1) Skin rash
2) Condylomata lata (wart like lesions)
3) Mucous patches - silvery grey erosions
4) Fever
5) Malaise
6) Weight loss
7) Generalised lymphadenopathy
8) CNS involvement in 40% - headache, meningism
In syphilis you can get spontaneous resolution of the secondary phase after 3-12 weeks what are the other 2 outcomes?
1) Latent - no clinical manifestation, positive serology
2) Without treatment 30% develop into tertiary syphilis
Without treatment 30% of patients with syphilis progress to the third stage, what are the 3 componenets of that?
1) Neurosyphilis
2) Cardiovascular
3) Late benign syphilis
What are the 3 main changes involved in neurosyphilis?
1) meningovascular - hemiplegia, seizures
2) Parenchymatous - general paresis (cortex) - get personality changes and Argyll Robertson pupils (don’t react to light)
3) Parenchymatous - tabes dorsalis (spinal cord) - demyelination of posterior column, ataxic wide based gait, lightening pains in legs and loss of proprioception and vibration sense
What are the 3 main changes in the cardiovascular component of tertiary syphilis?
1) Aortitis
2) Aortic regurgitation
3) Saccular aneurysm
What is late benign syphilis?
Non specific granulomatous reaction which involves the formation of gummas which can occur in any organ, most commonly bone/skin/ soft tissue
In terms of congenital, in utero transmission, which stage of syphilis is the most dangerous?
Spirochaetaemia in early syphilis
What are the 3 early signs of congenital syphilis?
1) Snuffles
2) Rash
3) Hepatosplenomegaly
What are the 4 late signs of congenital syphilis?
1) Frontal bosses
2) Saddle nose
3) Sabre shins
4) Hutchinson’s incisors
What 2 tests are used for direct detection of syphilis in diagnosis?
1) Darkfield microscopy of primary or secondary lesions
2) PCR - nucleic acids
As well as the direct tests for syphilis, there are some indirect blood tests, what in general do they detect?
Ab against the spirochaete, Treponema Pallidum which causes syphilis
What is the standard antimicrobial treatment for syphilis and what is the route of administration?
Penicillin based
IM/IV depends on sight and stage
When syphilis patients are given penicillin, in some it can cause a Jarish-Herxheimer reaction, particularly in secondary syphilis, what is this?
A self limiting, hypersensitivity reaction
Experience fever, chills and myalgia
What is trichomoniasis caused by?
Trichomonas vaginalis
What are the 2 main symptoms of trichomoniasis in men and in women?
Women
1) Profuse greenish frothy vaginal discharge
2) Mucosal inflammation
Men - usually asymptomatic but may get urethritis
What kind of organism is trichomoniasis?
Protozoan (lacks mitochondria)
How is a diagnosis of trichomoniasis made?
Microscopy/ culture of vaginal swab
What anti microbial is used to treat trichomoniasis?
Metronidazole
Bacterial (anaerobic) vaginosis (BV) is to do with changes in vaginal flora, what are the 2 main changes?
1) Reduced vaginal lactobacilli
2) Increased Gardenerella vaginalis and anaerobes
How is bacterial vaginosis diagnosed?
Watery discharge with has a positive KOH test, vaginal pH >4.5 and clue cells on microscopy
With what 3 antimicrobials can bacterial vaginosis be treated?
1) Metronidazole
2) Amoxycillin
3) Topical clindamycin
Candidiasis includes thrush and balanitis, what 3 factors can lead to the development of candidiasis?
Involves multiple factors
1) Oral contraceptives
2) Poorly controlled diabetes
3) Abx - inhibition of normal flora
What is the main source of candidiasis and route of transmission?
Bowel source - sexual transmission
What are the 5 signs and symptoms of candidiasis?
1) Vulval, vaginal and penile erythema
2) Itching/ irritation
3) Thick/ adherent discharge
4) White plaques
5) Maculopapular fissuring lesions
How is a diagnosis of candidiasis usually made?
Mainly a clinical diagnosis but can use microscopy and culture
Which pathogen causes candidiasis in 80-90% of cases?
Candida albicans
What is the treatment for uncomplicated candidiasis (c albicans, not recurrent, not severe)? 2
1) Topical agent eg. clo-trimazole
2) Fluconazole (single 150mg oral dose)
What is the treatment for complicated candidiasis? 3
1) Treatment for 10-14 days (topical or oral)
2) Consider treatment of partner
3) Longterm suppressive treatment if frequent recurrence
What 3 factors about the virus HIV have made it so aggressive and hard to treat?
1) RNA- based, there is a high rate of mutability so has a survival advantage
2) DNA intermediary - means it can hind from the host and incorporate into host genome
3) It actually infects host immune cells - reduction of host immune cell response
What are the 3 transmission routes of HIV?
1) Sexual - transmission at genital or colonic mucosa
2) Exposure to other infected fluids: blood/ blood products
3) Mother to infant
Which viral molecule reacts interacts with cellular receptor CD4 and chemokine receptor CD5 to gain entry to host cell?
Viral Glycoprotein gp120
After primary HIV infection what are the 5 possible symptoms of the early symptomatic phase?
1) Pulmonary TB
2) Persistent oral candidiasis
3) Unexplained chronic diarrhoea
4) Unexplained persistent fever
5) Severe bacterial infections
Which patients are tested for HIV?
- Have universal testing for GUM patients and pregnant women etc.
- Also suspect and test in high risk patients eg. IVDUs
What 2 methods are used to diagnose HIV?
1) Antibody testing
2) Viral PCR
Why is viral PCR a more useful diagnosis method than Ab testing?
Can give you a quantitative value - ie. can obtain a CD4 count from it
What are the 5 classes of anti virals used to treat HIV?
1) Nucleoside/ reverse transcriptase inhibitors
2) Non nucleoside revers transcriptase inhibitors
3) Protease inhibitors
4) Viral entry inhibitors
5) Integrase strand transfer inhibitors
Combinations of drugs are used to treat HIV in HAART (high active anti retroviral therapy), why is it important to use combinations?
To prevent resistant mutations emerging
How many stages of HIV are there, what are they based on and how is AIDS defined?
4 stages of HIV based on CD4 count
AIDS is end stage HIV, equivalent to stage 4 and is when CD4 count is less than 200
Is HIV curable?
Functionally cured toddler was found in US
What are the 2 emerging new treatments for HIV?
1) Allogenic stem cell transplants (replace all white cells)
2) Effective vaccine - ongoing but difficult because of high rate of mutability
