Skin and soft tissue infections Flashcards
skin and soft tissue infections
common syndrome
-cellulitis
-impetigo
-erysipelas
-furuncle
-carbuncle
-abscess
skin and soft tissue infections
likely pathogen
-S aureus, Group A alpha haemolytic (strep pyogenes) Group B strep agalactiae
skin and soft tissue infection
important historical information
CA-MRSA, risk profile,human or animal bite
Microbiology of SSTIs
gram positive
-S Aureus
-strep, enteroccous
gram negative
-enterobacteriae
.P.aerogenosa
Anaerobes
What is cellulitis
Cellulitis is inflammation of the skin and deep underlying tissues.
what is erysipelas
Erysipelas is an inflammatory disease of the upper layers of the skin.
what causative agent of cellulitis
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.
what is impetigo
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
treatment impetigo
• 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.
Staphylococcal Scalded skin
syndroms (SSSS)
• Abrupt Fever,skin tenderness • Generalised erythema
• Sloughing resembling scalding
• Caused by epidermolytic exotoxin from a group I Staphyloccus aureus, toxin Aand B
symptoms and treatment scalded skin syndrome
-Child is ill, irritable,feverish. The skin burn and
tender to touch
-Treatment with appropriate i/v penicillin,
fluid and electrolyte management
cause of scalded skin syndrome
• Caused by epidermolytic exotoxin from a group 2 Staphyloccus, toxin A and B
• In immunocompromised: HIV, chronic alcoholism, renal failure or malignancy
Necrotising faciitis
• Caused by Group A Streptococci and S.
aureus.
• Produce M protein and pyogenic exotoxin
Necrotising Fasciatis symptoms and treatment
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
Propionibacterium acnes and acne
• 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).
Treatment of Acne
• Topical antibiotics: tetracycline/erythromycin/clindamycin Comedolytics- Benzyl peroxide, Retinoids •Systematic:
Antibiotics
Anti Androgen
13-cis-retinoic acid
Physical: Lacer/dermabrasion
necrotizing infections of the skin and fascia
Necrotizing fasciitis
-stretococcua pyogenes
-mixed aerobic/anaerobic infection
Gas gangrene
-clostridium species
Cellulitis secondary to animal bites
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
Athelete Foot
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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.
how to prevent athelete foot
• 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.
What is Onycomycosis
Onychomycosis is a fungal infection of the fingernails or toenails that causes discoloration, thickening, and separation from the nail bed.
Treatment of Onycomycosis
• 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.
what prevention of onycomycosis
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
what cause of tinea capitis
Ringworm of the scalp, called “tinea capitis”, caused by a Microsporum sp..
Tinea capitis is CDC
what cause tinea faciei
dermatophytic
what cause pityriasis versicolor
Caused by Malassezia furfur Confirm by direct scrapping showing round yeast form
Tinea vesicolor or Pityriasis versicolor
Tinea vesicolor or Pityriasis versicolor
• Malassezia furfur, a lipophilic yeast and normal skin commensal.
Leprosy
-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
Fungal infection due to Microsporum canis floresces green under a Wood’s
lamp
• Tinea pedis
• Tinea cruris
• Tinea capitis
• Tinea barbae
herepes virus treatment
acyclovir
-induce thymidine kinase
-inhibition of viral dna polymerase incorporation into viral dna
-chain termination
ringworm - antifungal of choice
-griseofulvin and ketoconazole(oral)
candidiasis - antifungal of choice
fluconazole (oral) and nystatin (topical)
systemic mycoses - antifungal of choice
ketoconazole( oral)
amphotericin B (oral/iv)
