bacterial infection pt1

• Macule

  Flat discolored spot on the skin
• Papule


  Small, solid elevation of the skin
• Vesicle


  Small blister filled with clear fluid
• Pustule


  Elevation of the skin containing pus
• Plaque


  Flat, elevated lesion
• Nodule

  Solid elevation of the skin more than 5 mm
• Urticaria

  Raised, itchy reddened areas of the skin
• Petechiae

  Tiny red or purple spots on the skin
• Purpura

  Reddish-purple discoloration of the skin
• Ecchymosis

  Bruise, discoloration of the skin
• Ulcer

  Crater-like lesion in the skin
• Eschar

  Dry, leathery scab
• Staphylococcus aureus

  Gram-positive coccus arranged in grape-like clusters, a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin, the most dangerous of all of the many common staphylococcal bacteria
• Staphylococcus aureus

  • Produces enzymes & toxins for its pathogenicity and through direct invasion and destruction of tissues: skin and nasopharynx
• Skin infections are transmitted through:

  1. Direct contact with person having purulent lesions

  2. From hands of healthcare hospital workers

  3. From fomites like bed linens, contaminated articles
• Folliculitis

  Common skin condition in which hair follicles become inflamed, a pyogenic (pus-producing) infection involving the hair follicles, characterized by localized painful inflammation that heals rapidly after draining the pus
• Furuncle

  Also known as Boil, an infection of a hair follicle that has a small collection of pus (called an abscess) under the skin, an extension of folliculitis, characterized by larger and painful nodules with underlying collection of dead and necrotic tissue
• Carbuncle

  A red, swollen, and painful cluster of boils that are connected to each other under the skin, represents a coalase of furuncles that extends into the subcutaneous tissue with multiple sinus tracts
• Stye or Hordeolum

  Involves one or more of the small glands near the base of the eyelashes, a red & painful folliculitis often filled with pus
• Pyoderma/Impetigo

  Infection common in young children, primarily involves the face and limbs, starts as macule which later becomes a pus filled vesicle that ruptures and forms crust (honey-colored crust), there may be enlargement of the regional lymph nodes but no sign of systemic infection, can also be caused by Streptococcus pyogenes
• Staphylococcus Scalded Skin Syndrome (SSSS)

  Also known as Ritter's Disease, primarily found in newborns and young children, exfoliative toxin is responsible for the manifestations, only the outer layer of the skin is affected, hence there will be no scarring, sudden onset of perioral erythema or bullous (redness) that covers the whole body within 2 days, positive Nikolsky sign (when pressure is applied in the skin, it causes displacement of the skin)
• Staphylococcus Epidermidis

  Part of the normal flora of the skin, associated with "stitch abscess", UTI and endocarditis, it causes infections in individuals with prosthetic devices, cardiac devices, CNS shunts
• Streptococcus pyogenes

  Gram positive cocci arranged in pairs or chains, belongs to Group A beta hemolytic streptococcus (causes complete hemolysis of the blood), major virulence factor is M protein which is anti-phagocytic, produces enzymes and toxins responsible for the pathogenicity, some strains are encapsulated, associated with severe systemic infections
• Clinical manifestations of Streptococcal infections

  • Pyoderma (impetigo)
  • Erysipelas
  • Cellulitis
  • Necrotizing fascitis
• Pyoderma (Impetigo)

  A purulent skin infection that is localized and commonly involves the face, and the upper and lower extremities, starts as vesicles then progresses to pustules, lesions rupture and form honey-colored crusts, enlargement of the regional lymph nodes but no sign of systemic infection
• Cellulitis


  Involves the skin and subcutaneous tissue, the infected skin and the normal skin is not clearly differentiated, local inflammation with systemic signs
• Erysipelas


  Also known as St. Anthony's fire, superficial form of cellulitis, follows a respiratory or skin infection, affects the upper dermis and extends into the superficial cutaneous lymphatics, manifested by localized raised areas associated with pain, erythema (intense rash), warmth, lymphadenopathy, systemic manifestations: fever, fatigue, joint pains
• Necrotizing Fascitis

  Also known as 'flesh-eating' or streptococcal gangrene, involves deep subcutaneous tissue, starts as cellulitis then becomes bullous and gangrenous, spreads to the fascia then to the muscle and fats, may become systemic and cause multi-organ failure to death
• Complications of Streptococcal infections

  • Acute glomerulonephritis: commonly associated with skin infections
  • Rheumatic fever: associated with throat infections
  • Scarlet fever/Scarlatina: develops in some people who have strep throat, manifested by Strawberry tongue, bright red rash that covers most of the body, sore throat and fever
• Pseudomonas aeruginosa

  An opportunistic aerobic gram-negative bacillus, a frequent & common cause of nosocomial infection, capable of water-soluble pigments (pyocyanin-blue), resistant to most antibiotics, virulence is attributed to adhesins (flagella, pili, LPS), toxins (exotoxin A, pigments) & enzymes, transmitted through colonization of previously injured skin
• Pseudomonas aeruginosa is resistant to most antibiotics hence C & S must be done, preventive measures must be done and focused on preventing contamination of sterile hospital equipment and instruments and cross-contamination of patients by hospital personnel
• Clinical findings of Pseudomonas aeruginosa

  • Ocular keratitis in contact lens wearers, endocarditis and osteomyelitis in IV drug users
  • External otitis (swimmer's ear) in healthy people, and severe external otitis in diabetic patients
  • Respiratory failure caused by P. aeruginosa infection in many persons with cystic fibrosis
  • Frequent infection of extensive skin burns, which can lead to sepsis
• Clostridium perfringens

  Formerly known as C. welchii, or Bacillus welchii, gram positive bacilli, anaerobic and rarely produce endospores, produce 4 lethal toxin: alpha, beta, iota, epsilon toxin (alpha: most lethal toxin because it causes massive hemolysis and bleeding and tissue destruction), associated with soil, water & feces, mode of transmission is colonization of the skin following physical trauma and surgery
• Clinical findings of Clostridium perfringens

  • Cellulitis: common bacterial skin infection that causes redness, swelling, and pain in the infected area of the skin
  • Suppurative myositis: an acute intramuscular infection that spreads into the body of skeletal muscle, manifested by abscess formation of large muscle groups
  • Myonecrosis or gas gangrene: a life-threatening infection following trauma or surgery, characterized by massive tissue necrosis with gas formation, shock, renal failure, and death within 2 days of onset
• Bacillus anthracis


  A gram-positive, spore-forming rod: bamboo rod or medusa head appearance, produces anthrax toxin resulting in an ulcer with a black eschar, deadly disease to livestock and, occasionally, to humans, able to grow slowly in soil types that meet specific moisture conditions, endospores survived in soil tests for up to 60 years, can be used in bioterrorism

  
• Anthrax


  Bacterial disease caused by bacillus anthracis that can affect skin, lungs, or gastrointestinal tract depending on the portal of entry of the etiologic agent, the disease strikes primarily grazing mammals, such as cattle and sheep, people at risk are those who handle animals, hides, wool, and other animals

  
• Forms of Anthrax Disease

  • Cutaneous Anthrax
  • Pulmonary Anthrax (Inhalational Anthrax, Woolsorter's Disease)
  • Gastrointestinal Anthrax

  
• Mode of Transmission of Anthrax

  1. Inoculation into the open skin from either the soil or infected animal products

  2. Ingestion of infected meat or milk

  3. Inhalation of aerosolized spores

  
• Laboratory Diagnosis of Anthrax

  Blood test detects both inhalational and cutaneous cases of anthrax within an hour, the peripheral blood contains a large number of B. anthracis which is easily seen on gram-stain, spores can be done using Dorner stain or Wirtz Conklin

  
• Conjunctivitis


  Inflammation of the conjunctiva