Chapter 150 - Superficial Cutaneous Infections and Pyodermas

Question 1

Most common cause of superficial purulent skin infections

Answer 1

Staphylococcus aureus

Question 2

Carriage of Staphylococcus aureus is found in up to ___% of healthy people

Answer 2

30%

Question 3

Major commensal bacterium found on the surface of human skin

Answer 3

Staphylococcus epidermidis

Question 4

Common sites of colonization of Staphylococcus aureus in carriers (6)

Answer 4

Inguinal region
Axilla
Perirectal skin
Nasal mucosa
Pharynx mucosa
Rectal mucosa

Question 5

Formation of small crateriform pits that coalesce to form a large discrete defect with serpiginous borders on the plantar surface on the foot

Answer 5

Pitted keratolysis

Question 6

Etiologic agents of pitted keratolysis (3)

Answer 6

Kytococcus sedentarius
(Micrococcus sedentarius)
Dermatophilus congolensis
Corynebacterium sp

Question 7

Common complaint of pitted keratolysis

Answer 7

Sliminess of skin (70%)

Malodor (2/3)

Question 8

Treatment for pitted keratolysis

Answer 8

Aluminum chloride 20% solution
BPO 5% gel
Topical clindamycin, erythromycin, miconazole, fucidic acid

Question 9

Superficial bacterial infection characterized by well-defined irregular reddish brown patches in intertriginous areas or fissuring and white maceration in toe clefts between 4th-5th toes

Answer 9

Erythrasma

Question 10

Etiologic agent of erythrasma

Answer 10

Corynebacterium minutissum

Question 11

Wood’s lamp of erythrasma reveals ____ fluorescence due to ____

Answer 11

Coral red; coprophyrin III

Question 12

Management of erythrasma

Answer 12

BPO 5% wash
Topical clindamycin, erythromycin
If widespread, oral erythromycin 250mgQID for 14 days
Or Clarithromycin 1g PO single dose

Question 13

Bacterial infection of hair shaft that consist of tan, reddish, yellowish, or black concretions on surface of hair shaft

Answer 13

Trichobacteriosis

Question 14

Wood’s lamp of trichobacteriosis reveal a

Answer 14

Pale yellowish fluorescence

Question 15

Management of trichobacteriosis

Answer 15

Shaving
BPO 5% gel
Topical clindamycin/ erythromycin

Question 16

Pyogenes, Latin for

Answer 16

Pus generating

Question 17

After a group A Streptococcal infection, the ff may ensue (4)

Answer 17

Guttate psoriasis
Acute rheumatic fever
Rheumatic heart disease
Glomerulonephritis

Question 18

Key virulence factor of GAS infection

Answer 18

M protein

Question 19

Streptococci group which causes impetigo, cellulitis, otitis in newborns

Answer 19

Group B

Question 20

Intense perianal erythema with pain on defecation, blood streaked stools associated with anal fissure

Answer 20

Perianal group A streptococcal cellulitis

Question 21

Large tense blister filled with seropurulent fluid on volar skin pad of distal fingers and toes with erythematous base

Answer 21

Blistering distal dactylitis

Question 22

Ddx of acute lymphangitis

Answer 22

UE: sporotrichosis
LE: superficial thrombophlebitis

Question 23

Poststreptococcal pharyngitis occurs ___ weeks ff GAS impetigo; occurs ____ weeks ff GAS pharyngitis

Answer 23

3-6 weeks

1-3 weeks

Question 24

Most common cause of acute nephritis in children

Answer 24

PSGN

Question 25

Acute rheumatic fever occurs ___ weeks after GAS pharyngitis

Answer 25

2 weeks

Question 26

Symptoms of choreoathetosis, OCD, or tic disorder is associated with antecedent GAS infection

Answer 26

``` PANDAS Pediatric Autoimmune Neuropsychiatric Disorders with Streptococcal Infection ```

Question 27

Grps of streptococci implicated in impetiginous lesions, secondarily infected dermatitis, wound infections with lymphangitis

Answer 27

Grp C and Grp G

Question 28

Grps of streptococci isolated from infections of skin lesions secondary to ischemia or venous stasis involving perineal area and operative wound sites

Answer 28

Grp B and Grp D

Question 29

Grp of streptococci responsible for infections in meat handlers

Answer 29

Grp L

Question 30

Pattern __ of emm gene are associated with pharyngitis; pattern ___ with skin infections; and pattern ___ with both

Answer 30

ABC D E

Question 31

2 of key pore forming toxins

Answer 31

Streptolysin O | Streptolysin S

Question 32

Produces large pores in host cell membranes leading to apoptosis of neutrophils, macrophages, and epithelial cells

Answer 32

Streptolysin O

Question 33

Cytolytic activity against neutrophils, lymphocytes, RBCs, platelets leading to defective immune function

Answer 33

Streptolysin S

Question 34

Key role in host defense against GAS skin infections

Answer 34

TLR9

Question 35

Impt cell type in host defense against GAS and S aureus

Answer 35

Neutrophils

Question 36

Titers used to detect GAS pharyngitis

Answer 36

Antistreptolysin O titers

Question 37

Titers used to detect GAS skin infection

Answer 37

AntiDNAse B

Question 38

Treatment for GAS skin infections

Answer 38

``` Pen V PO 25-45 mkday for 10 days Or Erythromycin 30-50mkday for 10 days Or Benazathine Pen G 1.2 M U IM Or Clindamycin 20-30mkday for 10 days ```

Question 39

Used as secondary prophylaxis against recurrent GAS

Answer 39

Clindamycin 20-30mkday | Co-Amoxiclav 40mkday

Question 40

Sites of colonization in neonates

Answer 40

Skin Umbilicus Circumcision Conjunctiva

Question 41

Bullous impetigo cleaves ___ in the epidermis, resulting in clusters of thin roofed bulla, vesicles, and or pustules

Answer 41

Desmoglein 1

Question 42

Secondary infection of miliaria of neonates by S. Aureus

Answer 42

Periporitis staphylogenes

Question 43

Small fragile dome-shaped pustules at the infundibulum (ostium or opening) of a hair follicle often on the scalp of children, beard, axilla, extremities, and buttocks of adults

Answer 43

Follicular or Bockhart impetigo

Question 44

Deep folliculitis with perifollicular inflammation occurring in the bearded areas of face and upper lip

Answer 44

Sycosis barbae

Question 45

Deep chronic form of sycosis barbae associated with scarring occurring as a circinate lesion

Answer 45

Lupoid sycosis

Question 46

Differential for staphylococcus aureus folliculits 1. Pseudofolliculitis barbae 2. Folliculitis keloidalis 3. Perifolliculitis capitis A. Scalp B. Nape C. Lower beard area

Answer 46

C B A

Question 47

Difference of Staphylococcal folliculitis from dermatophyte folliculitis (3)

Answer 47

In fungal infections, 1. Hairs are broken and loosened 2. Presence of suppurative or granulomatous nodules than pustules 3. Painless plucking of hairs

Question 48

Deep seated inflammatory nodule that develops around a hair follicle from a preceding superficial folliculitis and evolves into an abscess

Answer 48

Furuncle

Question 49

More extensive, deeper, communicating, infiltrated, and serious inflammatory lesion

Answer 49

Carbuncle

Question 50

CA- MRSA should be suspected in all patients with a skin abscess. True or False

Answer 50

True

Question 51

Purulent, chronic, subQ infection with foregn trauma playing a role

Answer 51

Botryomycosis

Question 52

Predisposing factors of botryomycosis (4)

Answer 52

Trauma Immunosuppression Chronic alcoholism DM

Question 53

Purulent infection or abscess involving bulbous distal end of finger

Answer 53

Staphylococcal whitlow or felon

Question 54

Systemic inflammatory response syndrome (4)

Answer 54

36 < T> 38 Rr> 24 HR> 90 4,000 < WBC > 12,000

Question 55

Risk factors for S. Aureus SSTIs (5)

Answer 55

1. Colonization of S. Aureus in mucosal sites (nares) 2. Preexisting tissue injury or inflammation 3. Immunodeficiency disorders (HIV/AIDS) 4. Condition with defective neutrophil number or function (CGD) 5. Patients with genetic or acquired IL17 responses