MICROPARA CHAPTER 19

• Folliculitis


  Infection of the hair follicle, often called a pimple
• Folliculitis


  • Spread of infection into surrounding tissues can produce furuncles
  • Carbuncles occur when multiple furuncles grow together
• Staphylococcus


  Facultatively anaerobic, Gram-positive bacteria that are cocci typically arranged in clusters, tolerant of salt and desiccation

  
• Staphylococcus species commonly found on the skin

  • Staphylococcus epidermidis
  • Staphylococcus aureus

  
• Diagnosis of Folliculitis


  Isolation of Gram-positive bacteria in grapelike clusters from pus

  
• Dicloxacillin


  Semisynthetic penicillin, the drug of choice for treating folliculitis
• Vancomycin


  Used to treat resistant strains of folliculitis
• Prevention of Folliculitis


  • Hand antisepsis
  • Proper procedures in hospitals to minimize MRSA infections
• Staphylococcal Scalded Skin Syndrome (SSSS)


  Caused by one or two different exfoliative toxins produced by some Staphylococcus aureus strains

  
• Staphylococcal Scalded Skin Syndrome


  • No scarring because the dermis is unaffected
  • Death is rare but may be due to secondary infections

  
• Staphylococcal Scalded Skin Syndrome


  Disease occurs primarily in infants and is transmitted by person-to-person spread of bacteria

  
• Diagnosis, treatment, and prevention of Staphylococcal Scalded Skin Syndrome


  1. Diagnosed by characteristic sloughing of skin

  2. Treated by administration of antimicrobial drugs

  3. Widespread presence of S. aureus makes prevention difficult

  
• Impetigo (Pyoderma) and Erysipelas


  Most cases caused by S. aureus, some cases caused by Streptococcus pyogenes

  
• Virulence factors of S. aureus and S. pyogenes

  • M protein
  • Hyaluronic acid
  • Pyrogenic toxins

  
• Impetigo and Erysipelas


  The bacteria invade where the skin is compromised, transmitted by person-to-person contact or via fomites
• Impetigo occurs most in children, Erysipelas can also occur in the elderly
• Diagnosis, treatment, and prevention of Impetigo and Erysipelas

  1. The presence of vesicles is diagnostic for impetigo

  2. Treat with penicillin and careful cleaning of infected areas

  3. Prevent with proper hygiene and cleanliness
• Necrotizing Fasciitis


  Most cases caused by S. pyogenes, various enzymes and exotoxins facilitate invasion of tissues
• Necrotizing Fasciitis


  • S. pyogenes enters through breaks in the skin, usually spread person-to-person
  • Early diagnosis is difficult because symptoms are nonspecific
• Treatment of Necrotizing Fasciitis

  Treat with clindamycin and penicillin
• Acne


  Commonly caused by Propionibacterium acnes, a Gram-positive, rod-shaped diphtheroid commonly found on the skin
• Propionibacteria are normal microbiota, acne typically begins in adolescence but can occur later in life
• Diagnosis, treatment, and prevention of Acne

  1. Diagnosed by visual examination of the skin

  2. Treated with antimicrobial drugs and drugs that cause exfoliation of dead skin cells

  3. New treatment uses blue-light wavelength to destroy bacteria
• Cat Scratch Disease


  Caused by the Gram-negative bacterium Bartonella henselae, transmitted by cat bites or scratches
• Endotoxin


  The primary virulence factor of Bartonella henselae
• Diagnosis, treatment, and prevention of Cat Scratch Disease

  1. Diagnosed with serological testing

  2. Treated with antimicrobials
• Pseudomonas aeruginosa


  The causative agent of Pseudomonas infections, found in soil, decaying matter, and moist environments
• Virulence factors of Pseudomonas aeruginosa


  • Adhesins
  • Toxins
  • Polysaccharide capsule

  
• Pseudomonas Infection


  • Infection can occur in burn victims, bacteria grow under the surface of the burn and kill cells, destroy tissue, and trigger shock
• P. aeruginosa is rarely part of the microbiota but can cause infections throughout the body once inside
• Diagnosis, treatment, and prevention of Pseudomonas Infection

  1. Diagnosis can be difficult, pyocyanin discoloration indicates massive infection

  2. Difficult to treat due to multidrug resistance of P. aeruginosa

  3. P. aeruginosa is widespread, but infections typically don't occur in healthy individuals

  
• Rocky Mountain Spotted Fever

  Caused by Rickettsia rickettsii, characterized by a non-itchy spotted rash on the trunk and appendages
• Rocky Mountain Spotted Fever


  • Pathogen avoids digestion in the phagosome, disease follows damage to blood vessels
• Rocky Mountain Spotted Fever


  Transmitted via bite of infected tick
• Diagnosis, treatment, and prevention of Rocky Mountain Spotted Fever

  1. Diagnosed with serological testing

  2. Treated with various antimicrobials

  3. Prevented with the use of tick repellents and avoidance of tick-infested areas
• Cutaneous Anthrax


  Caused by Bacillus anthracis, characterized by a black, painless, ulcerous eschar
• Treatment and prevention of Cutaneous Anthrax

  1. Treated with antimicrobial drugs

  2. Prevention requires control of the disease in animals
• Gas Gangrene


  Caused by several Clostridium species, characterized by blackening of infected muscle and skin, and presence of gas bubbles
• Gas Gangrene


  • Bacterial endospores survive harsh conditions, vegetative cells secrete 11 toxins
  • Traumatic event must introduce endospores into dead tissue, mortality rate exceeds 40%
• Diagnosis, treatment, and prevention of Gas Gangrene

  1. Appearance is usually diagnostic

  2. Rapid treatment is crucial, including surgical removal of dead tissue and administration of antitoxin and penicillin

  3. Prevent with proper cleaning of wounds