Microbiology

Question 1

What bacterial species predominates in healthy vaginal flora?

Answer 1

Lactobacillus spp.

Question 2

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

Answer 2

Lactic acid +/- hydrogen peroxide

Suppresses growth of other bacteria creating INNATE IMMUNITY

Question 3

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

Answer 3

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

Question 4

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

Answer 4

Vaginal thrush
Bacterial vaginosis
Prostatitis

Question 5

Which bacteria causes vaginal thrush?

Answer 5

Candida (usually albicans)

Question 6

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

Answer 6

False

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

Question 7

List some predisposing factors to developing Candida infection

Answer 7

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

Question 8

Describe clinical presentation of vaginal thrush

Answer 8

Intensely itchy

White vaginal discharge “like cottage cheese”

Question 9

How is the diagnosis of vaginal thrush made?

Answer 9

Clinical diagnosis/appearance

High vaginal swab to culture for C. albicans

Question 10

How is vaginal thrush treated?

Answer 10

Topical clotrimazole

Oral fluconazole if no response

Question 11

What is characteristic of Candida albicans on gram film?

Answer 11

Appearance of budding

Question 12

Who typically gets other forms of Candida infection (other than albicans)? How does this present?

Answer 12

Poorly controlled diabetics
Immunosuppressed
C. balanitis: ‘spotty rash’ in males

Question 13

Which organisms are the main causes of bacterial vaginosis?

Answer 13

Gardnerella vaginalis
Mobiluncus sp.
Other anaerobes

Question 14

Describe clinical presentation of bacterial vaginosis

Answer 14

Thin, watery, bubbly, fish-smelling discharge that reeeeaally stinks (positive whiff test)

Question 15

How is a diagnosis of bacterial vaginosis made?

Answer 15

Clinical diagnosis/examination

Raised vaginal pH greater than 4.5

Question 16

The presence of what cells on microscopy suggest bacterial vaginosis?

Answer 16

Clue cells - vaginal epithelial cells coated with coccobacilli

Question 17

How is bacterial vaginosis treated?

Answer 17

Oral metronidazole for 7 days

Question 18

Describe the clinical presentation of acute bacterial prostatitis

Answer 18

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

Question 19

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

Answer 19

False

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

Question 20

How is acute bacterial prostatitis treated?

Answer 20

Ciprofloxacin for 28 days

Trimethoprim if high C. diff risk

Question 21

List the 3 main sexually-transmitted bacterial infections

Answer 21

Chlamydia
Gonorrhoea
Syphilis

Question 22

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

Answer 22

Chlamydia, caused by Chlamydia trachomatis

Question 23

What areas of the body can chlamydia infect?

Answer 23

Eyes
Throat
Rectum
Urethra
Cervix

Question 24

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

Answer 24

False

Obligate bacteria that only reproduces inside the host

Question 25

Does chlamydia stain with Gram stain?

Answer 25

No because no peptidoglycan in cell wall

Question 26

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

Answer 26

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

Question 27

What condition does lymphogranuloma venereum mimic on presentation?

Answer 27

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

Question 28

How is chlamydia infection treated?

Answer 28

Doxycycline for 7 days | 3 weeks if LGV

Question 29

Which bacteria causes gonorrhoea?

Answer 29

Neisseria gonorrhoeae

Question 30

Gonorrhoea is more common than chlamydia. True/False?

Answer 30

False

Question 31

Describe the appearance of Neisseria gonorrhoeae on gram stain

Answer 31

Gram -ve Diplococcus (2 kidney beans facing each other)

Question 32

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

Answer 32

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

Question 33

What is the typical clinical appearance of gonorrhoea?

Answer 33

Purulent discharge | Pus cells under microscope

Question 34

How are both chlamyida and gonorrhoea diagnosed?

Answer 34

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

Question 35

What are the advantages of NAAT/PCR over culture?

Answer 35

Quick Less invasive More sensitive

Question 36

What are the disadvantages of NAAT/PCR over culture?

Answer 36

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

Question 37

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

Answer 37

True

Question 38

What is the recommended treatment for gonorrhoea?

Answer 38

IM ceftriaxone (+azithromycin orally)

Question 39

Which bacteria causes syphilis?

Answer 39

Treponema pallidum, spirochaete organism

Question 40

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

Answer 40

True

Question 41

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

Answer 41

True

Question 42

How does stage 1 syphilis present?

Answer 42

Chancre (painless ulcer)

Question 43

How does stage 2 syphilis present?

Answer 43

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

Question 44

How does latent stage (stage 3) syphilis present?

Answer 44

No symptoms

Question 45

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

Answer 45

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

Question 46

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

Answer 46

True

Question 47

What method is used to diagnose syphilis, and chancre?

Answer 47

PCR

Question 48

How is serology testing for syphilis done?

Answer 48

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

Question 49

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

Answer 49

Rapid plasma regain | Useful for monitoring response to therapy

Question 50

List the main specific serological tests done for syphilis

Answer 50

TPPA TPHA IgM + IgG ELISA (screening test)

Question 51

What is the gold-standard treatment for syphilis?

Answer 51

Penicillin injection

Question 52

What are the 3 main sexually-transmitted viral infections?

Answer 52

Genital warts Genital herpes Hepatitis and HIV

Question 53

What is the commonest viral STI and its cause?

Answer 53

Genital warts, caused by human papilloma virus

Question 54

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

Answer 54

6 + 11

Question 55

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

Answer 55

16 + 18

Question 56

How is genital warts diagnosed?

Answer 56

Clinical diagnosis as no lab test

Question 57

How are genital warts treated?

Answer 57

DESTRUCTION via cryotherapy/toxic cream (topical podophylin) Vaccination given to 11-13 year old girls

Question 58

What virus causes genital herpes?

Answer 58

Herpes simplex virus types 1 &2 | Type 1 also cold sores

Question 59

How is genital herpes diagnosed?

Answer 59

Swab for PCR | No good test between recurrent episodes

Question 60

How is genital herpes treated?

Answer 60

Aciclovir Pain relief Counselling

Question 61

What is the most common sexually-transmitted parasitic disease?

Answer 61

Trichomonas vaginalis (single cell protozoal parasite)

Question 62

How is Trichomonas vaginalis diagnosed?

Answer 62

High vaginal swab for microscopy

Question 63

How is Trichomonas vaginalis treated?

Answer 63

Oral metronidazole

Question 64

Which parasite causes pubic lice? How is it spread?

Answer 64

Phthirus pubis | Close genital skin contact

Question 65

How are pubic lice treated?

Answer 65

Malathion lotion

Question 66

What are the clinical consequences of bacterial vaginosis infection?

Answer 66

Increased risk of upper UTI Premature rupture of membranes and preterm delivery Increased risk of acquiring HIV

Question 67

Sole extragenital gonorrhea infection is most common in which group of people?

Answer 67

MSM - rectal gonorrhea as a single site of infection (50%) and is routinely screened for

Question 68

How is genital herpes spread?

Answer 68

Genital-genital contact | Oropharyngeal-genital contact

Question 69

Describe the pathogenesis of genital herpes

Answer 69

Virus replicates in dermis and epidermis spreading to nerves and causing painful inflammation Virus hides from the immune system in sacral roots Virus can reactivate and cause recurrent attacks

Question 70

What are the clinical signs of Trichomonas vaginalis?

Answer 70

Vaginal discharge and irritation in females

Question 71

What are the clinical signs of Phthirus pubis?

Answer 71

Itching in pubic areas