Microbiology

Question 1

2 types of necrotising fasciitis

Answer 1

Type 1 – mixed anaerobes & coliforms, usually post-abdominal surgery
Type II – Group A Strep infection

Question 2

Indication for taking swabs for leg ulcers

Answer 2

If signs of cellulitis or infection present

Question 3

Organisms worth treating in leg ulcers

Answer 3

Strep. pyogenes (Group A), Staph. aureus
Other beta-haemolytic streptococci (B, C, G)
?Anaerobes – esp. diabetic patients

Question 4

Where does tinea capitis affect?

Answer 4

Scalp

Question 5

Where does tinea barbae affect?

Answer 5

Beard

Question 6

Where does tinea corporis affect?

Answer 6

Body

Question 7

Where does tinea manuum affect?

Answer 7

Hand

Question 8

Where does tinea unguium affect?

Answer 8

Nails

Question 9

Where does tinea cruris affect?

Answer 9

Groin

Question 10

Where does tinea pedis affect?

Answer 10

Foot

Question 11

Dermatophyte pathogenesis

Answer 11

Fungus enters abraded or soggy skin
Hyphae spread in stratum corneum
Infects keratinised tissues only (skin, hair, nails)
Increased epidermal turnover causes scaling
Inflammatory response provoked (dermis)
Hair follicles and shafts invaded
Lesion grows outward and heals in centre, giving a “ring” appearance

Question 12

Who is more likely to be affected by dermatophyte infections?

Answer 12

Males more commonly affected
Scalp ringworm mainly affects children
Foot and groin ringworm mainly affects men

Question 13

Sources of dermatophyte infections

Answer 13

Other infected humans (antrhopophilic fungi)
Animals (zoophilic)
Soil (geophilic)

Question 14

How do we diagnose dermatophyte infections?

Answer 14

Clinical appearance
Woods light (fluorescence)
Skin scrapings, nail clippings, hair - send to lab for microscopy and culture (2 weeks +)

Question 15

What is the treatment for small areas of infected skin & nails infected by dermatophytes?

Answer 15

Clotrimazole (Canesten) cream

Topical nail paint (amorolfine)

Question 16

What is the treatment for dermatophyte scalp infections?

Answer 16

Terbinafine orally

Itraconazole orally

Question 17

Treatment for candida skin infection

Answer 17

Clotrimazole cream, oral fluconazole

Question 18

What is the incubation period for scabies?

Answer 18

6 weeks

Question 19

Commonly affected areas itchy in scabies?

Answer 19

Finger webs, wrists, genital area

Question 20

Treatment for scabies

Answer 20

Malathion lotion applied overnight to whole body
Benzyl benzoate (avoid in children)

Question 21

Treatment for lice (pediculosis)

Answer 21

Malathion

Question 22

Which pts need single room isolation and contact precautions?

Answer 22

Patients with Group A Strep infection
Patients with MRSA infection
Patients with Scabies (N.B. long sleeved gowns also required for Norwegian scabies)

Question 23

Complications of chickenpox

Answer 23

Pneumonitis
Scarring
Encephalitis

Question 24

Predictors of severity in chickenpox

Answer 24

Extremes of age

Depressed cell-mediated immunity

Question 25

What is post-herpetic neuralgia?

Answer 25

Nerve pain due to damage caused by varicella zoster virus
Usually confined to a dermatome
Beyond week 4

Question 26

What is Ramsay-Hunt syndrome?

Answer 26

Vesicles and pain in auditory canal and throat
CN VII facial palsy
Irritation of 8th cranial nerve - deafness, vertigo, tinnitus
Also known as geniculate or otic herpes zoster

Question 27

Compare HSV types 1 and 2

Answer 27

HSV Type 1:
main cause of oral lesions
causes half of genital herpes
causes encephalitis

HSV Type 2:
rare cause of oral lesions
causes half of genital cases
encephalitis / disseminated infection (particularly in neonates)

Question 28

What is the treatment for VZV & HSV? How does it work?

Answer 28

Aciclovir
Selectively incorporated into viral DNA inhibiting replication
Does not eliminate latent virus

Question 29

What is erythema multiforme?

Answer 29

Pt has usually reacted to an infection, often herpes simplex, or to a drug
Lesions w/ erythema appear for 1-2 weeks or until the responsible drug or other factor has gone

Question 30

Appearance of molluscum contagiosum

Answer 30

Fleshy, firm, umbilicated, pearlescent nodules

1-2mm in diameter

Question 31

Which types of HPV are associated w/ warts/verrucae?

Answer 31

Types 1 to 4

Question 32

Which types of HPV are associated w/ genital warts?

Answer 32

6 & 11

Question 33

Which types of HPV are associated w/ cervical cancer?

Answer 33

16 & 18

Question 34

Current vaccine in UK that protects against HPV, protects against which types?

Answer 34

6, 11, 16, 18

Question 35

What is herpangina?

Answer 35

Blistering rash of back of mouth caused by enterovirus

Question 36

Which viruses cause hand, foot and mouth disease?

Answer 36

Enteroviruses esp. coxsackie viruses

Not same viruses as animal disease of similar name

Question 37

Cause of death in fatal cases of hand, foot & mouth?

Answer 37

Pulmonary oedema

Question 38

Erythema infectiosum (slapped cheek disease) is caused by which virus?

Answer 38

Parovirus B19

Question 39

How does erythema infectiosum present differently in children and adults?

Answer 39

Children - slapped cheek appearance, as rash on the face fades a lacy macular rash on the body appears
Adults - rash may be absent, acute polyarthritis of the small joints (e.g. hands)

Question 40

What are some complications of parovirus B19?

Answer 40

Spontaneous abortion
Aplastic crises - sudden drop in haemoglobin
Chronic anaemia in immunosuppressed pts

Question 41

Who gets Orf? How does it look?

Answer 41

Most commonly seen on hands of shepherds, butchers, vets & meat porters
Lesions (single or multiple) which start as small firm papules that change into flat-topped pusturlar nodules w/ a erythematous surround