Infectious disease IV

Question 1

Causative organisms of Lyme disease

Answer 1

Spirochete Borrelia species

B.burgdoferi
B.afzelii
B.garini

Question 2

Transmission of Lyme disease

Answer 2

Ticks bite, at least 24 hours on human to transmit

NO person-to-person

Question 3

Three stages of Lyme disease

Answer 3

Stage 1: 1 - 4 weeks - red, circular rask around the bite + flu-like symptoms

Stage 2: weeks - months - spread of organism -> arthritis, cardiac and CNS issues

Stage 3: months - years - chronic arthritis, skin lesions, progressive CNS and cardiac dysfunction

Question 4

Treatment for Lyme disease

Answer 4

Doxycycline for early stages

If arthritis associated, ceftriaxone

Question 5

What microorganism cause acne?

Answer 5

Propionibacterium species

Question 6

What is acne?

Answer 6

Excessive sebaceous secretions, inflammation and infection.

Severe inflammation or furunculosis leading to scarring.

Question 7

Treatment of acne.
<Mild, Moderate, Severe case>

Answer 7

Mild case: topical adaplene AND benzoyl hydroxide

Moderate case: topical clindamycin OR topical erythromycin

Severe case: PO antibiotics (tetracyclines or erythromycin in pregnancy and young children) AND topical adaplene AND benzoyl hydroxide

Question 8

What is used to control sebum production in acne patients?

Answer 8

Co-cyprindol - in women only

Isoretinoin

Question 9

How to distinguish Staph and Strep in the lab?

Answer 9

Hydroxide peroxide

Staph has catalase -> can survive -> show oxygen bubble

Question 10

What is Furunculosis?

Answer 10

Infection of sweat glands or sebacous glands around the hair follicles.

Question 11

What microorganisms cause Furunculosis?

Answer 11

Staphylococcus aureus

Question 12

What clinical features do skin conditions caused by Staph.aureus normally associated with?

Answer 12

Abscess - large amount of pus

Question 13

How can Staph.aureus well-tackle the immune response?

Answer 13

Produce leukocidin to lyse neutrophils

Produce coagulase to promote fibrin formation -> protect them

Question 14

Treatment of furunculosis.

Answer 14

Mild - small or moderate pustular lesion: good hygiene -> heal spontaneously

Moderate - Large lesion and carbuncles: PO flucloxacillin or PO cloxacillin

Severe case: IV flucloxacillin or cloxacillin

Question 15

What should be done with remained pus after antibiotic treatment?

Answer 15

Remove

If large pustules and abscess -> aspired or sugically drained

Question 16

Pathogenesis of furunculosis.

Answer 16

• Staphylococcus aureus infects the hair follicle and proliferates -> inflammation.
• Plug-off of the hair follicle as well as the abscess formation at the infected site.
• This condition begins as small papules that increase in size and tenderness. In some cases, some may point and discharge the yellowish pus before gradually resolving.
• After many abscessed are formed, multiple of them can interconnect to form carbuncles which might involve neighbouring glands giving rise to a composite lesion.

Question 17

What is impetigo?

Answer 17

Infection of surface of epidermis

Common in children

Question 18

What microorganism cause impetigo?

Answer 18

Staphylococci

Group A Streptococci like Streptococcus pyogenes

Question 19

Progression of impetigo.

Answer 19

• Initiated by the colonisation of unbroken skin occurs either exogenously skin-to-skin contact or endogenously from another site, usually anterior nares (noses) or oropharynx (mouth or throat).
• Takes 10 to 14 days, initiated through lesions such as minor abrasions or insect bites.
• Painless blisters, usually on face especially near the nose and mouth. The blisters are filled with clear or yellow fluid but then there will be crust over. Those spots are normally small, but it can extend to form plaque-like inflamed lesion on which a yellowish exudate forms and dries into thick scabs.
• Those lesions are irritating and sore. The scratching or rubbing due to itchiness contribute to the spread at adjacent and distant sites, at the same time further damage the skin for infection progression.

Question 20

Treatment of impetigo

Answer 20

Mild: topical fusidic acid OR topical mupirocin (esp MRSA)

Severe case: PO flucloxacillin or cloxacillin x 5- 7 days
Alternative: PO macrolides

If severe caused by MRSA -> check susceptibility, must NOT use glycopeptides immediately