Bacterial & Fungal skin, Soft Tissue & Muscle infections For Second Year Medical Students Prof. Dr Asem Shehabi

Infections of Skin & Soft Tissues Infections depends upon the Layers of Skin & Soft Tissues involved ( epidermis, dermis, subcutis, muscle).. Infections may involve several layers. Skin Infections are associated with: swelling ,tenderness, warm skin, blisters, ulceration, fever headache.. Rare Systemic disease. Few Normal Bacteria & Yeast live in hair follicles.. Skin .. may cause inflammation of Hair follicles ..folliculitis, Abscess formation ( Boils)..

Skin Infections

Type of Skin Infection Skin infection increased .. production Androgenic Hormones.. Puberty… Increase activities Sebaceous ducts..Increase Sebum (Fatty Acid+ Peptides)… Increase keratin & presence of desquamation … Anaerobic Propionibacteria acnes ( gram+ve small bacilli) & Staph spp. excrete Enzymes.. Splitting Sebum ..cause inflammation ..develop Acne vulgaris Certain Systemic Infection may cause skin infection ..N. meningitidis (Haemorrhagic Lesions) Salmonella typhi ( skin Rash, Rose spots), Treponem pallidum ..Syphilis.. Pseudomonas aeruginosa.. Rash

Acne

Common Normal Skin Flora & Pathogens Staphylococci, hemolytic Streptococci (Group A) Micrococci, Propionibacteria , Acinetobacter , Pityrosporum (Yeasts) S. aureus (coagulase+ve) is the most common & important cause of human Skin diseases.. Various Enterotoxins & Enzymes..Coagulase, DNAse, Hemolysins , Hayluronidase . About 15-40 per cent of healthy humans are healthy carriers of S. aureus in their nose or skin.. Infants carry S. aureus in feces Common Clinical skin features S.aureus Folliculitis / Furuncles .. Hair follicular-based papules and pustules.. Erythematous lesions.. affect All ages.

- Impetigo: Epidermis, Crusted lesions. Skin sores - Impetigo: Epidermis, Crusted lesions.. Skin sores.. face and extremities.. Common Young children -Toxic Schlock Syndrome: Systemic Infection..high fever, Rash & Skin Desquamation due to Release Toxic Shock Syndrome Toxin-1 (TSST-1 ).. Super- antigens toxin.. Activate T-lymphocytes.. Release Cytokines.. General massive inflammatory response, hypotension, Shock, Comma.. Vomiting, diarrhea multiple organ failure.. Hepatic inflammation, kidney failure, Death.. Common children > five years old, menstruated Women. - Scalded Skin Syndrome: Exfoliative A,B Toxins.. Minor Skin Lesion.. Destruction Skin Intercellular Connection .. Large Blisters Containing Fluid .. Skin Scaling.. Painful.. Common Babies

- Methicillin Resistant S. aureus S. epidermidis.. normal inhabitants of the skin surface.. but Less Pathogenic. Most its infections occur in normal individuals.. Dry Skin.. Injury.. but underlying illness increase the risk of infection.. Infants.. compromised patients Staphylococci are becoming increasingly resistant to many commonly used antibiotics including: Penicillins-Cephalospoins.. Methicillin & flucloxacillin , Augmentin (amoxycillin + clavulonic acid) .. B-lactamase-resistant penicillins.. Other antibiotics Worldwide Spread Methicillin resistance (MRSA).. 20-90% ..in Jordan about 60% clinical isolates (2004)

Diagnosis &Treatment of staphylococcal infections Lab Diagnosis of staphylococcal infections should be confirmed by: culture, gram-stain positive cocci, +ve catalase , coagulase test . Effective treatment For MRSA .. Vancomycin, Teicoplanin, Imipenem, Fusidic acid Drainage of pus collections before treatment Surgical removal (debridement) of dead tissue (necrosis) Removal of foreign bodies (stitches) that may be a focus of persisting infection Treating the underlying skin disease

Streptococcal Skin Infections-1 Streptococcus pypgenes / B-H-Group A) ..Major virulence factors: M-Protein .. Hemolysin O & S, Pyrogenic exotoxins -Erythrogenic toxin .. Causing Scarlet fever + Toxic Shock Syndrome, Hayluronidase , Streptokinase (Fibrinolysin- digest Fibrin & Proteins in Plasma), Streptodornase (DNA) Cellulites : Acute Rapidly Spreading Infection in Skin & Subcutaneous Tissues.. Following.. Wounds, Burns.. Highly Communicable Erysipelas : Massive Brawny Edema.. Dermis.. Children Impetigo: Pyoderma Superficial Layers Skin.. Epidermis, Blisters, Children.. Highly Communicable.. Following Streptococcus Sore Throat

B-H-Streptococci

/2 - Necrotizing fasciitis : Following wound infection.. Subcutaneous Tissues & Fascia, Rapid Spread Necrosis.. Tissue Liquidation.. Fatal without Rapid Antibiotic Treatment - Scarlet fever: Following Group A Strept. Infection.. Erythematous Rash due to Erythrogenic Toxin.. Children - Streptococcal Toxic Shock Syndrome: Pyrogenic Exotoxin A.. Invasive Group A, Infected Trauma .. Bacteremia, Respiratory & Multi Organ Failure, 30% Death Allergic hypersensitivity ..Erythema Nodosum.. Vasculitis

Skin rash - Scarlet Fever

Diagnosis & Treatment Culture on blood, B-Hemolytic reaction, Gram-+ve cocci in chain, catalase-ve, Bacitracin-Susceptible Serotyping should used to confirm group of streptococcal infection.. A, B, C etc. using antisera against group-specific cell wall carbohydrate –Antigens (Lancefield classification) Penicillin is the drug of choice.. All Group A streptococci are very sensitive to penicillin. Patients with penicillin allergy may be given Erythromycin.. Azithromycin..

Less Common Bacterial associated with Skin Infections Gonorrhea : Neisseria gonorrhoea.. Skin rash Soft chancre /chancroid : Haemophilus ducreyi.. STD.. Painful Skin Ulcer, Extra Genitalia, Tropical countries Syphilis: Treponema pallidum.. Genital ulcers.. Meningococemia : N. meningitidis.. Skin rash & hemorrhage .. Thrombosis Rickettsia diseases: human lices.. Transmit R. prowazeki (Typhus), R. rickettsii (Spotted fever).. Pseudomonas aeruginosa : Wound infections, Burns skin follicultis