Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

2021-22 Clinical microbiology > STI's > Flashcards

STI's Flashcards

(63 cards)

Start Studying
1
Q

What is a STI?

A

An illness caused by an infectious microorganism with a propensity (ease) to transfer between humans through sexual contact (vaginal, oral, anal, sex toys)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

True or False: STI’s are a major problem worldwide

A

True!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

True or False: In the UK, STIs, are the greatest communicable disease problem

A

True

•>1.5 million attendances at genitourinary medicine (GUM) clinic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the cost burden of STI’s to the NHS?

A

£750 million / annum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the cost burden of HIV and other STI’s to the NHS?

A
  • HIV: £580 million
  • Others (gonorrhoea, herpes, syphilis etc): £65 million
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

STI’s are associated with high morbidity and mortality; they disproportionately affect which groups?

A
  • Young people with high risk (unprotected) sexual lifestyles
  • Men who have sex with men (MSM)
  • Disadvantaged socio-economic communities (poor educational awareness or resources)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Microorganisms associated with common STI:

Chlamydia trachomatis

A

Non -specific urethritis

Chlamydia trachomatis does not have a fully formed cell wall- difficult to grow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

No. of new cases of non-specific urethritis in the UK (2018)

A

218,095

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Microorganisms associated with common STI: Neisseria gonorrhoae

How many new cases in the UK (2018)?

A

Gonorrhoea

56,259

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Microorganisms associated with common STI: Treponema pallidum

How many new cases in the UK (2018)?

A

Syphilis

7,541

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Microorganisms associated with common STI: Papillomavirus

How many new cases in the UK (2018)?

A

Genital warts

57,259

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Microorganisms associated with common STI: Herpes simplex

How many new cases in the UK (2018)?

A

Oral and genital herpes

33,867

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Microorganisms associated with common STI: Hepatitis B/C

How many new cases in the UK (2018)?

A

Hepatitis

5 Million

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Microorganisms associated with common STI: HIV

How many new cases in the UK (2018)?

A

AIDS

4,484 (43% MSM)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Microorganisms associated with common STI: Candida albicans

How many new cases in the UK (2018)?

A

Thrush

80,000

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Microorganisms associated with common STI’s: Trichomonas Vaginalis (parasite)

How many new cases in the UK (2018)?

A

Vaginitis

8,000

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Microorganisms associated with common STI: Sarcoptes scabei (arthropod)

A

Genital scaies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Microorganisms associated with common STI: Phthirus pubis (arthropod-crab louse)

A

Pediculosis pubis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Incidence of STI is increasing:

How can our modern way of life contribute?

A

(a) Multiple partners; more promiscuous
(b) Pregnancy – morning after pill
(c) Internet chat rooms; geo-location apps (Blendr / Grindr) allow people to readily contact each other

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Incidence of STI is increasing:

Name some important factors

A
  • Drugs / alcohol (mind altering chemicals)
  • MSM
  • multiple partner exchange
  • ‘risky’ sexual practices
  • Contraceptive pill (potentially discourages the use of protective barriers such as condoms)
  • Lack of education / awareness about STI’s
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

STI’s on the rise - and in the press

A

Common themes in headlines:

  • Alcohol
  • Young people
  • MSM
  • Lack of awareness of contraception
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Which microorganism causes chalmydia?

A

Chlamydia trachomatis

Does not have a fully developed cell wall so difficult to stain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How is chlamydia transmitted?

A
  • Via vaginal, anal and oral sex
  • Transmitted vertically from mother to baby at birth
  • Incubation: 1-3 weeks
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Describe the clincal manifestations of chlamydia

A

•Frequently asymptomatic (the silent epidemic):

75% women / 50% men; reservoirs of infection that don’t know they have chlamydia

  • Male: urethritis (watery, mucoid discharge)
  • Female: urethritis / cervicitis / vaginitis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What are some of the complications associated with chlamydia?
(a) Pelvic Inflammatory Disease (PID) also called salpingitis: 40% (b) Infertility in male (lowers sperm count) and female (c) Ocular infection (conjunctivitis): neonates / adults
26
What is the NCSP? When was it established? What is its aim?
The National Chlamydia Screening Programme (NCSP) - Established in 2003: Control and prevention programme - AIM: detection and treatment of asymptomatic carriers in uni's GP's etc
27
What is the target group of the NCSP? What locations are there? How may tests were carried out 2003-2012? How many silent infections were diagnosed?
- TARGET GROUP: people \< 25 who are sexually active (approx 1:10 POSITIVE but asymptomatic) - LOCATION: Contraceptive services; abortion clinics; GP surgeries; community pharmacies; outreach clinics; non-health settings 2003- 2012: 5.5 million tests carried out Of that 5.5 million, 370,000 ‘silent infection’ diagnosed (approx. 7%)
28
How is chlamydia treated?
* **Azithromycin** (belongs to macrolides so targets protein synthesis) (Clamelle): single dose; 2 x 500mg * Doxycycline (Vibramycin): 7-14 days; 200mg
29
Chlamydia positivity by venue type and sex
30
What STI does the human papillomavirus cause?
Genital warts * 100 types * (antigenic types 6, 11, 16, 18 account for over 70% of infections)
31
How is HPV transmitted?
* Via vaginal, anal and oral sex * Incubation: 1-6 months; years * Prevalence greatest (17-33 YOA)
32
What are the clinical manifestations of HPV?
•Warts (90% caused by HPV antigenic types 6 /11); multiple, dry, keratinised, ‘cauliflower’ in appearance; painless NEOPLASIA (CANCER) •Neoplastic conversion (eg. can cause cervical cancer if you are not vaccinated): HPV antigenic types 16 / 18- high risk
33
Show the number of HPV-induced cancers (worldwide)
100% of cervical cancer cases are caused by HPV Mouth, vagina and throat cancer is also significantly associated
34
How is HPV treated?
•Genital (surfcae) warts - **Podophyllin** (cytotoxic) - **Imiquimod** (immunostimulatory) •Cervical /(deeper) intraurethral – CO2 laser removal
35
How can HPV be prevented?
Prevention: •Vaccination ( during year 8, secondary school) - Quadrivalent vaccine Gardasil® ( effective against HPV antigens 6, 11, 16, 18) (NHS, 2012) - Girls: 2009 - Boys: 2019 Given in 2-3 shots Long period of activity (up to 10 years) •Safe sex
36
What STI does the herpes simplex virus cause?
Herpes Can be herpes simplex type 1 (traditionally caused oral herpes) and 2 (traditionally cased genital herpes) (HSV1 -40%; HSV2 -60%)
37
What are the clinical manifestations of herpes (reactivation)?
•Tenderness, pain, and burning at the site of eruption lasting 2 hours to 2 days - Women: Lesions on the labia and perineum - Men: Lesions on the shaft, prepuce, glans. •Lesions heal in 7-10 days; dissemination, encephalitis Virus resides in your nerve cells and reactivates when you are ill/ immunocompromised
38
How is herpes transmitted?
•Via vaginal, anal and oral sex Incubation period of 3-7 days
39
What are the clinical manifestations of herpes (primary infection)?
* Asymptomatic in 70% cases * Symptoms: constitutional and localised * Untreated attack lasts approx 28 days; latency
40
How is herpes treated?
* Acyclovir (Zovirax): 200mg, 5 x daily for 1 week * Famciclovir (Famvir): 200-250mg, 3 x daily for 1 week There is no cure
41
Describe Neisseria gonorrhoeae
* GRAM NEGATIVE DIPLOCOCCUS; * intracellular survival * strict human pathogen
42
How can herpes be prevented?
By safe sex
43
What microorganism causes gonorrhoea?
Neisseria gonorrhoeae
44
How is Neisseria gonorrhoeae transmitted?
•Via vaginal, anal and oral sex Affinity for non-ciliated columnar epithelial cell * Incubation period: 2-7 days * Transmission rates following single exposure: male-20%; female-80% Females more likely to become more infected because the male ejaculate may contain Neisseria gonorrhoea •Mother to baby transmission
45
Describe the epidemiology of gonorrhoea?
* Rates higher in urban regions esp. London * Men form 70% of the diagnoses; MSM and black ethnic groups account for 1/3 of these * Female16-19 years; male 20-24 years
46
What percentage of asymptomatic cases of gonorrhoea are there?
•Gonorrhoea is asymptomatic in many cases - 70% female - 10% male
47
What are the clinical manifestations of gonorrhoea in males?
(a) Urethritis (urethral inflammation) (b) Dysuria (pain on urination) (c) Thick, purulent penile discharge
48
What are the clinical manifestations of gonorrhoea in females?
(a) Dysuria (b) Cervicitis (inflammation of the cervix) (c) Thick, purulent (sometimes bloody) vaginal discharge * Rectal infection: anal discharge, pain on anal sex * Throat infection: tonsillitis; purulent exudate
49
What are the complications of gonorrhoea in males?
Epididymitis, prostatitis
50
What are the complications of gonorrhoea in males?
(b) Females (20%): spread to fallopian tubes (salpingitis); pelvic inflammatory disease (PID); infertility * Opthalmia neonatorum * 1% Disseminated gonococcal infection (DGI) DGI: bloodstream infection –fever, sepsis, arthritis, skin lesions
51
Pathogenesis: Virulence Factors Stage 1: Adherence and endocytosis
(a) Pili (good at attaching to non-ciliated columnar epithelial cells) (b) Opa (opacity) proteins and LOS (lipooligosaccharide) which also helps the organism to attach (c) Por (porin) proteins (parasite directed endocytosis) allow organism to become internalised into human cells
52
Pathogenesis: Virulence Factors Stage 2: Adherence and endocytosis
(a) Capsule (organism surrounds itself with our own sialic acid, this is molecular mimicry.) (b) IgA protease (against the most abundant antibody within the urogenital system, IgA)
53
Pathogenesis: Virulence Factors Stage 3: Adherence and endocytosis
(a) transferrin binding proteins- Tbp1 , Tbp2 (b) lactoferrin binding protein- Lbp 1
54
Laboratory diagnosis of gonococcal infection: Sample collection
(A)Sample collection * Males: urethral swab (3cm insertion and rotation) * Females: multiple samples; urethral / endocervical / vaginal * Other samples depending upon patient history / clinical presentation : throat / rectal / blood cultures * Transport medium eg. Stuart’s * Direct examination and culture of clinical samples in GUM clinic preferred
55
Laboratory diagnosis of gonococcal infection: Non- culture techniques
•Direct microscopy of discharge (see lots of white blood cells with lots of gram negative diplococci within them) Presumptive diagnosis if positive; initiate treatment Nucleic acid amplification tests (NAAT) Amplify the bacterial antigen on the swab or in the urine PCR-based: Rapid; detects / amplifies specific DNA; bacterial viability not essential
56
Laboratory diagnosis of gonococcal infection: Culture techniques
* ENRICHED agar: Blood / chocolate agar * SELECTIVE agar: Modified Thayer-Martin / New York City agar; vancomycin, colistin, nystatin, trimethoprim * 37oC / 48h / 5% CO2 * Opaque, convex, grey, glistening colonies, 2mm
57
Laboratory diagnosis of gonococcal infection: Identification and confirmation of N. gonorrhoeae isolated by culture
* Colonies: Gram-negative diplococci * Oxidase + (organism contains cytochrome oxidase C * Catalase + (breaks down H2o2 into H2O and O2 * CHO fermentation (glucose+, maltose-, sucrose-); API * Prolyl aminopeptidase + (red coloration) (Gonochek II, commercially available)
58
How is gonococcal infection treated/
•Many strains now resistant to common antibiotics eg. penicillin (18%), ciprofloxacin (quinolone) (22%), tetracycline (48%) British National Formulary Guidelines: (a) ceftriaxone (250mg; IM; single injection) (b) cefixime (400mg; oral; single dose) (c) azithromycin (2g single dose)
59
2013: Combination therapy for DRNG NICE Guidelines for treatment of uncomplicated gonorrhoea (2017)
* 500mg ceftriaxone (single dose, injected into the muscle) AND * 1g azithromycin (single dose, orally)
60
Describe the main method of preventing of gonococcal infection
Safe sex (a) Minimise number of sexual partners (b) Use condoms during mouth-to-penis sex, vaginal and anal intercourse
61
2017: ETX-0914 (Zoliflodacin, phase 3)
Describe
62
Key points: STI
* STI are caused by numerous microorganisms; associated risk factors * Top 5 acute STIs are chlamydia, genital warts, herpes, gonorrhoea and syphilis * N. gonorrhoeae possesses a variety of virulence factors * Clinical spectrum of gonorrhoea: asymptomatic – symptomatic; associated with complications * Laboratory diagnosis is essential to confirm the identity of the causative agent and determine antimicrobial sensitivity * Combination therapy needed for DRNG * Prevention is better than cure!
63
Why is Neisseria gonorrhoea becoming resistant to azithromycin?
N. Gonorrhoea may be exposed to sub-lethal levels of azithromycin intended for the treatment of chlamydia

2021-22 Clinical microbiology (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions