Skin and soft tissue infections

Question 1

skin and soft tissue infections
common syndrome

Answer 1

-cellulitis
-impetigo
-erysipelas
-furuncle
-carbuncle
-abscess

Question 2

skin and soft tissue infections
likely pathogen

Answer 2

-S aureus, Group A alpha haemolytic (strep pyogenes) Group B strep agalactiae

Question 3

skin and soft tissue infection
important historical information

Answer 3

CA-MRSA, risk profile,human or animal bite

Question 4

Microbiology of SSTIs

Answer 4

gram positive
-S Aureus
-strep, enteroccous

gram negative
-enterobacteriae
.P.aerogenosa

Anaerobes

Question 5

What is cellulitis

Answer 5

Cellulitis is inflammation of the skin and deep underlying tissues.

Question 6

what is erysipelas

Answer 6

Erysipelas is an inflammatory disease of the upper layers of the skin.

Question 7

what causative agent of cellulitis

Answer 7

Group A streptococcus
• always pencillin susceptible but macrolide resistance is increasing-2007 UNC data (7.5% erythromycin resistant); clindamycin resistance, both inducible and constitutive (as detected by D-test) is 6% with 2/3 of resistance being inducible. TMP/SMX is not active against GAS.
• Cellulitis can progress to GAS necrotizing fasciitis , mortality with GAS necrotizing fasciitis is approximately 50% at UNC.

Staphylococcus aureus
• CA-MRSA is the most common strain causing wound infection in outpatients and is
common in inpatients as well.
• These organism continue to be susceptible to TMP/SMX and doxy but fluorquinolone resistant is becoming more common

Group B streptococci
• seen in cellulitis in diabetics as well as a chronic infection in these patients
• As with GAS, organism remains susceptible to penicillin G but both macrolide (37%) resistance and clindamycin (31%; 25% constitutive) resistance is high.

Question 8

what is impetigo

Answer 8

Impetigo is an acute,contagious, superficial skin infection caused by bacteria.
• Usually the cause is staphylococcal (staph) but sometimes streptococcus (strep) .
• It is most common in children between the ages of two and six.
• It usually starts when bacteria get into a break in the skin, such as a cut, scratch or insect bite.
• Symptoms start with red or pimple-like sores surrounded by red skin.
• These sores can be anywhere, but usually they occur on your face, arms and legs.
• The sores fill with pus, then break open after a few days and form a thick crust.
• They are often itchy, but scratching them can spread the sores.
• Impetigo can spread by contact with sores or nasal discharge from an infected person.
• Predisposing factor include eczema or developed secondary bacterial infection

Question 9

treatment impetigo

Answer 9

• Tipical antibiotics, e.g. Fucidin or mupirocin
• Systemic antibiotics for 5 days
• Streptoccal respond to penicillin or erythromycin
• For resistance staphylococcal strains, flucloxacillin are prefered.

Question 10

Staphylococcal Scalded skin
syndroms (SSSS)

Answer 10

• Abrupt Fever,skin tenderness • Generalised erythema
• Sloughing resembling scalding
• Caused by epidermolytic exotoxin from a group I Staphyloccus aureus, toxin Aand B

Question 11

symptoms and treatment scalded skin syndrome

Answer 11

-Child is ill, irritable,feverish. The skin burn and
tender to touch
-Treatment with appropriate i/v penicillin,
fluid and electrolyte management

Question 12

cause of scalded skin syndrome

Answer 12

• Caused by epidermolytic exotoxin from a group 2 Staphyloccus, toxin A and B
• In immunocompromised: HIV, chronic alcoholism, renal failure or malignancy

Question 13

Necrotising faciitis

Answer 13

• Caused by Group A Streptococci and S.
aureus.
• Produce M protein and pyogenic exotoxin

Question 14

Necrotising Fasciatis symptoms and treatment

Answer 14

Localised painful redness and swelling
progress to hypotention, high fever,
tachypnoea, tachycardia, hypocalcaemia,
altered mental state and collapse.
Treatment:
Wound debribement, Antibiotic
including penicillin and clindamycin Cephalosporin and
Erythromycin have been use

Question 15

Propionibacterium acnes and acne

Answer 15

• Hormonalchangesinpubertyresultinacne
• Blockageoftheductleadtosacformation
• Predispose to P. acne and other microflora to multiply
• P.acneactonsebumtoprodufattyacidand peptides
• Enzymesothersubstancesreleasebybacteria and polymorph causes inflammation
• Comedonesaregreasyplugscomposedof keratin, sebum and bacteria and capped by a layer of melanin (blackhead).

Question 16

Treatment of Acne

Answer 16

• Topical antibiotics: tetracycline/erythromycin/clindamycin Comedolytics- Benzyl peroxide, Retinoids •Systematic:
Antibiotics
Anti Androgen
13-cis-retinoic acid
Physical: Lacer/dermabrasion

Question 17

necrotizing infections of the skin and fascia

Answer 17

Necrotizing fasciitis
-stretococcua pyogenes
-mixed aerobic/anaerobic infection

Gas gangrene
-clostridium species

Question 18

Cellulitis secondary to animal bites

Answer 18

Pasteurella multicoda
• oxidase positive organism; short, gram negative rod that does not grow on MacConkey agar
• more common following cat bites than dog bites although dog bites are much more common
• bacteremia uncommon

Cellulitis secondary to human bites
• Because of the complexity of the human oral microflora, these tend to be complicated
cultures; always assume anaerobes are present
• need to figure out if either Eikenella corrodens or Actinobacillus are present because they are difficult to treat; both have distinctive phenotype with Eikenella producing a strong bleach odor and pitting of the agar while Actinobacillus colonies have a cross- appearance in the center

Question 19

Athelete Foot

Answer 19

• •
• •
• •
Athelete Foot
Also called: Tinea pedis
Athlete’s foot is a common infection caused by the tinea fungus.
Symptoms include itching, burning and cracked, scaly skin between your toes.
Tinea grows best in damp, dark and warm places, which is why it often develops between your toes.
It can spread to your toenails, as well, making them thick and crumbly. You can get athlete’s foot from damp surfaces, such as locker room floors.

Question 20

how to prevent athelete foot

Answer 20

• Wash your feet every day
• Dry your feet well, especially between your toes
• Wear clean socks
• Don’t walk barefoot in public areas
• Wear flip-flops in locker room showers
• Treatments include
• antifungal creams for most cases and prescription medicines for more serious infections.

Question 21

What is Onycomycosis

Answer 21

Onychomycosis is a fungal infection of the fingernails or toenails that causes discoloration, thickening, and separation from the nail bed.

Question 22

Treatment of Onycomycosis

Answer 22

• Onychomycosis is very difficult and sometimes impossible to treat, and therapy is often long-term.
• topical treatments that are applied directly to the nails, as well as two systemic drugs, griseofulvin and ketoconazole.
• griseofulvin and ketoconazole.
• itraconazole (Sporanox), terbinafine (Lamisil), and fluconazole (Diflucan).
• fewer side effects.
• blood count and liver enzyme workup every four to six weeks.
• Terbinafine in particular has markedly less toxicity to the liver, .
• Nail debridement is another treatment option
• A combination of oral, topical, and surgical removal can increase the chances of curing the infection.

Question 23

what prevention of onycomycosis

Answer 23

Prevention
• Keeping the feet clean and dry, and washing with soap and water
• keeping the nails cut short
• Regular changes of shoes and socks.
• socks made of synthetic fibers, which can absorb moisture more quickly than those made of cotton or wools.
• Manicure and pedicure tools should be disinfected after each use.
• nail polish

Question 24

what cause of tinea capitis

Answer 24

Ringworm of the scalp, called “tinea capitis”, caused by a Microsporum sp..
Tinea capitis is CDC

Question 25

what cause tinea faciei

Answer 25

dermatophytic

Question 26

what cause pityriasis versicolor

Answer 26

Caused by Malassezia furfur Confirm by direct scrapping showing round yeast form

Question 27

Tinea vesicolor or Pityriasis versicolor

Answer 27

Tinea vesicolor or Pityriasis versicolor
• Malassezia furfur, a lipophilic yeast and normal skin commensal.

Question 28

Leprosy

Answer 28

-Systemic infection cause by Mycobacterium leprae
-Affection the skin and peripheral nerve
Hypopigmented, scally maculesClassification:
Tuberculoid-few organisms in the skin, Well demarcated anaesthetic
Intermediate-Initial stage, nonspecific

Question 29

Fungal infection due to Microsporum canis floresces green under a Wood’s
lamp

Answer 29

• Tinea pedis
• Tinea cruris
• Tinea capitis
• Tinea barbae

Question 30

herepes virus treatment

Answer 30

acyclovir
-induce thymidine kinase
-inhibition of viral dna polymerase incorporation into viral dna
-chain termination

Question 31

ringworm - antifungal of choice

Answer 31

-griseofulvin and ketoconazole(oral)

Question 32

candidiasis - antifungal of choice

Answer 32

fluconazole (oral) and nystatin (topical)

Question 33

systemic mycoses - antifungal of choice

Answer 33

ketoconazole( oral)
amphotericin B (oral/iv)