Microbiology Flashcards

1
Q

What bacterial species predominates in healthy vaginal flora?

A

Lactobacillus spp.

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2
Q

What does Lactobacillus spp. produce and what is the effect of these products?

A

Lactic acid +/- hydrogen peroxide
Suppresses growth of other bacteria

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3
Q

List some bacteria other than Lactobacillus spp. that can be part of the normal vaginal flora

A

Strep viridans
Group B Strep
Candida spp. (small numbers)

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4
Q

What are the 3 main non-sexually-transmitted genital tract infections?

A

Vaginal thrush
Bacterial vaginosis
Prostatitis

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5
Q

Which bacteria causes vaginal thrush?

A

Candida (usually albicans)

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6
Q

The presence of Candida on vaginal swab indicates vaginal thrush. True/False?

A

False
30% of females are colonised by small numbers of Candida as part of normal flora

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7
Q

List some predisposing factors to developing Candida infection

A

Recent antibiotic therapy
High oestrogen levels (pregnant, contraceptives)
Poorly controlled diabetes
Severely immunocompromised

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8
Q

Describe clinical presentation of vaginal thrush

A

Intensely itchy
White vaginal discharge “like cottage cheese”

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9
Q

How is the diagnosis of vaginal thrush made?

A

Clinical diagnosis/appearance
Vaginal swab to culture for C. albicans

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10
Q

How is vaginal thrush treated?

A

Topical clotrimazole
Oral fluconazole if no response

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11
Q

What is characteristic of Candida albicans on gram film?

A

Appearance of budding

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12
Q

Who typically gets other forms of Candida infection (other than albicans)?

A

Poorly controlled diabetics (C. balanitis)
Immunosuppressed

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13
Q

Which organisms are the main causes of bacterial vaginosis?

A

Gardnerella vaginalis
Mobiluncus sp.
Other anaerobes

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14
Q

Describe clinical presentation of bacterial vaginosis

A

Thin, watery, fish-smelling discharge that reeeeaally stinks

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15
Q

How is a diagnosis of bacterial vaginosis made?

A

Clinical diagnosis/examination
Raised vaginal pH greater than 4.5

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16
Q

The presence of what cells on microscopy suggest bacterial vaginosis?

A

Clue cells

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17
Q

How is bacterial vaginosis treated?

A

Oral metronidazole

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18
Q

Describe the clinical presentation of acute bacterial prostatitis

A

UTI-like
Abdominal/back/perineal/penile pain
Tender prostate

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19
Q

A mid-stream sample of urine is required to test for urethral infection in acute bacterial prostatitis. True/False?

A

False
Mid-stream for upper UTI, first-pass for lower UTI

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20
Q

How is acute bacterial prostatitis treated?

A

Ciprofloxacin for 28 days
Trimethoprim if high C. diff risk

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21
Q

List the 3 main sexually-transmitted bacterial infections

A

Chlamydia
Gonorrhoea
Syphilis

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22
Q

What is the commonest bacterial STI in the UK? What organism causes it?

A

Chlamydia, caused by Chlamydia trachomatis

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23
Q

What areas of the body can chlamydia infect?

A

Eyes
Throat
Rectum
Urethra
Cervix

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24
Q

Chlamydia reproduces both in and out -side the host cell. True/False?

A

False
Obligate bacteria that only reproduces inside the host

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25
Q

Does chlamydia stain with Gram stain?

A

No because no peptidoglycan in cell wall

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26
Q

What are the 3 serological groupings of chlamydia and their respective infections?

A

Serovars A-C = trachoma/eye infection
Serovars D-K = genital infection
Serovars L1-L3 = lymphogranuloma venereum

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27
Q

What condition does lymphogranuloma venereum mimic on presentation?

A

Inflammatory bowel disease - features of proptosis, PR bleed, irritation, fullness

28
Q

How is chlamydia infection treated?

A

Doxycycline for 7 days
Azithromycin if uncomplicated
3 weeks if LGV

29
Q

Which bacteria causes gonorrhoea?

A

Neisseria gonorrhoeae

30
Q

Gonorrhoea is more common than chlamydia. True/False?

A

False

31
Q

Describe the appearance of Neisseria gonorrhoeae on gram stain

A

Gram -ve
Diplococcus

32
Q

Neisseria gonorrhoea is a fastidious organism. What does this mean?

A

Doesn’t grow well in less than ideal conditions i.e. outside the body

33
Q

What is the typical clinical appearance of gonorrhoea?

A

Purulent discharge

34
Q

How are both chlamyida and gonorrhoea diagnosed?

A

Nucleic acid amplification test
PCR
Microscopy of swabs
Specific agar culture (gonorrhoea only)

35
Q

What are the advantages of NAAT/PCR over culture?

A

Quick
Less invasive
More sensitive

36
Q

What are the disadvantages of NAAT/PCR over culture?

A

Will detect dead organisms so have to wait 5 weeks before retest
Cannot detect antibiotic sensitivity

37
Q

Many strains of gonorrhoea are now antibiotic resistant. True/False?

A

True

38
Q

What is the recommended treatment for gonorrhoea?

A

Ceftriaxone + azithromycin

39
Q

Which bacteria causes syphilis?

A

Treponema pallidum

40
Q

Treponema pallidum does not stain with gram stain. True/False?

A

True

41
Q

Treponema pallidum cannot be grown in culture. True/False?

A

True

42
Q

How does stage 1 syphilis present?

A

Chancre (painless ulcer)

43
Q

How does stage 2 syphilis present?

A

Flu-like symptoms
Ulcers
Generalised rash, palms and soles affected

44
Q

How does latent stage (stage 3) syphilis present?

A

No symptoms

45
Q

How does late-stage (stage 4) syphilis present?

A

Cardiovascular (aortic aneurysm)
Neurovascular (high-stump gait)

46
Q

Syphilis is not infectious in the latent period. True/False?

A

True

47
Q

What method is used to diagnose syphilis?

A

PCR

48
Q

How is serology testing for syphilis done?

A

Test for non-specific and specific antibodies to T. pallidum in blood

49
Q

What is the main non-serological test done for syphilis? When is it useful?

A

Rapid plasma regain
Useful for monitoring response to therapy

50
Q

List the main specific serological tests done for syphilis

A

TPPA
TPHA
IgM + IgG ELISA (screening test)

51
Q

What is the gold-standard treatment for syphilis?

A

Penicillin injection

52
Q

What are the 3 main sexually-transmitted viral infections?

A

Genital warts
Genital herpes
Hepatitis and HIV

53
Q

What is the commonest viral STI and its cause?

A

Genital warts, caused by human papilloma virus

54
Q

What subtypes of HPV are the most common causes of genital warts?

A

6 + 11

55
Q

What subtypes of HPV are associated with increased risk of cervical cancer?

A

16 + 18

56
Q

How is genital warts diagnosed?

A

Clinical diagnosis as no lab test

57
Q

How are genital warts treated?

A

DESTRUCTION via
cryotherapy/toxic cream
Vaccination given to 11-13 year old girls

58
Q

What virus causes genital herpes?

A

Herpes simplex virus types 1 &2

59
Q

How is genital herpes diagnosed?

A

Swab for PCR

60
Q

How is genital herpes treated?

A

Aciclovir
Pain relief

61
Q

What is the most common sexually-transmitted parasitic disease?

A

Trichomonas vaginalis

62
Q

How is Trichomonas vaginalis diagnosed?

A

Vaginal swab for microscopy

63
Q

How is Trichomonas vaginalis treated?

A

Oral metronidazole

64
Q

Which parasite causes pubic lice?

A

Phthirus pubis

65
Q

How are pubic lice treated?

A

Malathion lotion