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REPRO > Microbiology of GU Tract > Flashcards

Microbiology of GU Tract Flashcards

1
Q

What are common bacterial causes of STIs? (2)

A
  • Chlamydia Trachomatis
  • Neisseria Gonorrhoea
----sidelines: Mycoplasma Genitalium
Treponema Pallidum (syphillis)
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2
Q

Viral causes of STIs? (2)

A
  • Genital warts: HPV
  • Genital Herpes: HSV
  • Hepatitis and HIV
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3
Q

What parasites may cause STI?

A
  • Trichomonas Vaginalis
  • Phthirus Pubis (“crabs”/pubic lice)
  • Scabies
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4
Q

What is characteristic of Gonococci?

State a clincal symptom.

A
  • huge PUS formation d/t an INTENSE neutrophil response

- pain with urination

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5
Q

How diff. is an infection by C.Trachomatis?

A
  • prodn of a MILD, watery discharge

- or no symptoms at all

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6
Q

What is taken into account for index of the infectiousness of the case ?

A
  • conc. and PHENOTYPE of the organism
  • susceptibility of the sexual partner
  • resistance of the host (hereditary/acquired or innate)
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7
Q

What should be kept in mind when testing for a specific STI?

A
  • IMMUNITY is RARE
  • re-infections are common
  • vaccine development is difficult
  • THEREFORE check for multiple STI
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8
Q

Which pathological lesion of the GU tract can predispose a person to acquiring HIV ?

A
  • Genital ULCERS
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9
Q

Which 2 STIs contribute to urethritis?

A
  • Gonorrhoea
  • Chlamydia
  • —coninfections are common so CHECK for ALL
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10
Q

What is the importance of specifically choosing which patients for STI testing?

A
  • ensure from the hx that STI testing is required

- or they are likely to fall in the FALSE positive region

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11
Q

What bacterial spp. is predominant in the normal vaginal flora?

A
  • Lactobacillus spp.

L.Crispatus and L.jesenii

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12
Q

What pH does the normal vaginal flora create and why?

A
  • d.t prodn of LACTIC ACID +/- hydrogen peroxide by the lactibacillus spp.
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13
Q

Apart from the lactiobacillus spp. in the normal vaginal flora, what other organisms are found in the flora?

A

+/- Group B Beta-hemolytic streptococcus (get rid of in pregnancy)

+/- Candida spp. *small no. is NORMAL

+/- Strep Viridans gr.

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14
Q

Describe the appearance of lactobacillus on epithelial cell on histology.

A
  • Gram Positive bacilli

- purple staining of the rod-shaped bacteria

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15
Q

How does Candida Albican appear on gram film?

A
  • budding

- Yeasts and Hyphae

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16
Q

What are predisposing factors of Candida?

A
  • RECENT antibiotic therapy
  • high estrogen levels (pregnancy/ contraceptives)
  • poor DM control
  • immunocompromised pts ( low CD4 counts and HIV )
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17
Q

How is a candida infections presented as and how to diagnose it?

A
  • INTENSELY itchy w/ WHITE vaginal discharge

- dx by HIGH vaginal swab for culture

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18
Q

How to treat candida vaginal infection?

What specific fungal pathogen is apparently resistant to azoles?

A
  1. TOPICAL CLOTRIMAZOLE (pressary/cream)…available as OTC
  2. Oral FLUCONAZOLE

….non-albicans candida species are more likely to be azole resistant

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19
Q

What is a candidal infection in men called and how does it present as?

A
  • Candida Balantitis
  • red spotty rash on penis
  • —very uncommon
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20
Q

Describe the pathogenesis of the GC infection…

A

GC attaches to HOST epithelium cells and is endocytosed within the host cell and released into the sub-epithelium space

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21
Q

What cascade of chemokines is triggered with a typical GC urethral infection?

A
  • prominent inflammation and
  • release of lipo-oligosaccharide and peptidoglycan fragments
  • release chemotactic factors
  • this attracts neutrophils
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22
Q

Why do some gonoccal strains cause asymptomatic genital infection?

A
  • differences in the organism’s ability to bind complement-regulatory proteins that DOWNREGULATE the prodn of chemotactic peptides
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23
Q

Describe the appearance of N.Gonorrhoea with gram stain and under the microscope.

A
  • Gram (-)ve INTRACELLULAR diplococci

- paired PINK spheres in the cell

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24
Q

How common is N.Gonorrhoea and which part of the body does it infect?

A
  • much LESS common than chlamydia

- infects the URETHRA, RECTUM, throat and eyes and endocervix

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25
Q

What is characteristic of the lifeline of N.gonorrhoea?

A
  • it’s a Fastidious organism (dies easily)

- therefore should do molecular tests to check for its presence

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26
Q

How to test for presence of N.Gonorrhoea?

A
  1. Microscopy of urethral/ endocervical swabs
  2. Culture on Selective AGAR plates (for rectal, throat and endocerival swabs)—may come out as false negative
  3. NAATs- urine specimen and vaginal swabs
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27
Q

What is NAAT?

A
  • Nucleic Acid Amplification Test
  • increase in sensitivity
  • searches the genetic material of the micro-organism
28
Q

What is required for the pt to do, after they have done their first NAAT test?

A

—–pt to come in, in 5 weeks time to do “test for cure” tests

29
Q

What is the commonest STI in the UK and what areas are commonly affected ?

A
  • chlamydia trachomatis

- urethra, rectum, throat and eyes, endocervix

30
Q

Why is C.Trachomatis known as an energy parasite?

A
  • it does NOT reproduce OUTSIDE a host cell

- it’s an obligate intracellular bacteria with biphasic life cycle

31
Q

What serological groupings of chlamydia trachomatis are a/w an STI?

A

Serovars D-K (genital infection)

Serovars L1-L3 (lymphogranuloma venereum)

32
Q

Which chlamydial sero group is a/w MSM?

A
  • L1-L3
33
Q

What is treatment for C.Trachomatis?

A
  • Doxycycline 100mg bd x 7 days
  • azithromycin 1g single dose
  • erythromycin for 14 days
34
Q

How is the NAAT test sample obtained from men and women differently?

A

Men: First pass URINE sample; not mid-stream
Female: High vaginal swab or vuvlo-vaginal swab, or endo cervical (speculum needed tho)
—–for both: rectal, throat and eye swabs
—-vuvlo-vaginal can be SELF-TAKEN

35
Q

What is the historic mainstay dx of the gonorrhea?

A

by CULTURE; generally with antibiotic-containing selective media

36
Q

What are the advantages of NAATs?

A
  • slight increase in sensitivity over culture

- can test urine specimens and vaginal swabs

37
Q

What is a disadvantage of NAAT?

A
  • can’t perform antimicrobial susceptibility testing

- poor or inadequately defined positive predicitve value of some NAAT when -used to test LOW-prevalence popns

38
Q

What is the risk of performing NAAT in an area of low prevalence of N.Gonorrhoeae?

A
  • risk of FALSE-POSITIVE screening
39
Q

What is Trichomonas vaginalis/Bacterial Vaginosis caused by?

A
  • a single celled protozoal parasite
  • divides by binary fission (human host)
  • transmitted by sexual contact
40
Q

What does trichmonas vaginalis present as?

A
  • vaginal discharge (frothy and fishy smell)
  • vaginal bleeding
  • genital burning/itching
41
Q

How to dx and rx t.vaginalis?

A
  • high vaginal swab for MICROSCOPY (PCR test)

- rx: Oral metronidazole

42
Q

What will a wet mount reveal for bacterial vaginosis?

A
  • the ABSENCE of lacto-bacilli

- a lot of CLUE cells (as epithelial cells are coated with coccobacili)

43
Q

Which STI is a.w increased risk of HIV acquisition?

A

women with Bacterial vaginosis d/t disturbance of microbiology

44
Q

What is the danger with BV and pregnancy?

A
  • risk of pre-term delivery

- d/t Premature rupture of the membranes

45
Q

Which STI condition is a.w Upper genito-tract infection?

A
  • Bacterial vaginosis

- —-may cause endometritis and salpingitis

46
Q

How to treat Bacterial vaginosis?

A
  • directed against the anaerobic flora with metronidazole for 7 days
    —-relapse is 30 %
    (no benefit from treating male sexual partners)
47
Q

What is syphilis caused by?

A
  • TREPONEMA PALLIDUM

does not stain gram stain

48
Q

How is syphilis diagnosed?

A
  • PCR or Serological blood tests

- –can’t be grown in artificial culture media

49
Q

Can a syphilis test come across as positive despite not having sexual contact?

A
  • yes
  • 3 more Treponema Palidum Subspecies that are non-sexually transmitted variants; but can’t be serologically differentiated from one another
  • Syphilis; Yaws; Bejel; Pinta
50
Q

What are the 4 stages of syphilis?

A
  1. Primary Lesion (chancre): innoculation site
  2. Secondary Stage: systemic manifestations
  3. Latent Stage- no symptoms (spirochaete multiply in t.intima of small blood vessels)
  4. Late Stage- CVS/ Neurovascular complications years later (DEMENTIA/ TABE DORSALIS/ gait imbalance/GUMMA/AORTIC ANEURYSM and CORONARY ARTERITIS)
51
Q

What are the manifestations in the secondary stage of syphilis?

A
  • generalised rash
  • flu-like symptoms
  • meningitis
  • nephritis
  • “snail-track” mouth ulcers
  • neurosyphilis, aseptic meningitis, CN defiicits
52
Q

Why is an animal model challenging for syphilis?

A
  • because humans are the ONLY HOST for syphilis
53
Q

What are the non-specific serological tests for syphilis ?

What are these tests useful for?

A
  • VDRL (venereal diseases research lab)
  • RPR (rapid plasma reagin)
  • to monitor RESPONSE to therapy…(usually negative after successful rx/over time)
54
Q

When are non-specific serological test for syphilis falsely positive?

A
  • SLE
  • Malaria
  • Pregnancy
55
Q

How to dx Primary stage Syphilis?

A
  • PCR
  • IgM (+)ve in 1st 2 weeks
  • dark ground microscopy
56
Q

How to dx secondary and tertiary stage Syphilis?

A

-by serology

57
Q

If the combined syphilis IgM and IgG screening test comes out as positive , what is then done?

A
  • IgM ELISA
  • VDRL test/ RPR
  • TPPA test
58
Q

Rx of syphilis?

A
  • injection of long-acting penicillin

—can’t check sensitivities to syphilis strain as it cannot grow in artificial culture

59
Q

Why is syphilis known as one of the most sensitive yet resistant bacteria?

A
  • sensitive: smallest penicilin conc. is bactericidal

- resistant: the time for which it MUST BE exposed to, to be killed

60
Q

What causes genital herpes?

A

HSV 1 and HSV2

  • —enveloped virus containing double stranded DNA
  • —spread by genital-genital or oropharyngeal-genital
61
Q

What is the pathogenesis of genital herpes?

A
  • virus replicates in DERMIS and epidermis
  • gets in NERVE endings (why VERY painful)
  • multiple small vesicles appear
  • —-virus migrates to sacral root ganglion and “hides” —may reactivate later
  • —–intermittent “virus SHEDDING” may occur
62
Q

How to dx herpes?

A
  • swab of virus of deroofed blister for PCR test

- serology (IgG)

63
Q

How to treat herpes?

A
  • aciclovir
  • pain relief
  • —pre- and post- exposure vaccines SUCK
64
Q

How to treat pubic lice?

A
  • Malathion Lotion
65
Q

How long do the lice live for?

A

Male: ~22days
Females: 17 days

REPRO (55 decks)

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