1. Staphylococcus
   1. Characteristics
      1. gram positive, bunches of round cells
      2. aerobic, facultative anaerobe; grow on many media
      3. nonflagellated, nonmotile, non spore forming
   2. Coagulase-positive
      1. S. aureus
         1. coagulase
            1. promotes clotting of plasma
            2. coating of staph w/fibrin impedes phagocytosis
         2. toxins
            1. alpha-toxin
            2. lyses RBC, causes necrosis
            3. inserts into lipid bilayer to form pores
            4. pyrogenic exotoxins
            5. toxic shock syndrome toxin (TSST-1)
            6. stimulates cytokins
            7. enterotoxins
            8. food poisoning
            9. stimulates IL-1&2 in GI
            10. stimulates medullary vomiting center
            11. exfoliatins
            12. separation and loss of superficial layers of epidermis
            13. protease cleaves desmosomes
            14. scalded skin syndrome
            15. Panton-Valentine leukocidin (PVL)
            16. pore formation in neutrophils and monocytes
            17. activation, degran, release of inflam
            18. skin abscesses, furuncles, necrotizing pneumonia
         3. other virulence factors
            1. teichoic acid
            2. adherence to cell walls and clots
            3. surface protein A
            4. binds Fc of IgG preventing complement activation
            5. peptidoglycan
            6. activation of complement and coag cascades
            7. septic shock
            8. catalase
            9. allows S. aureus to survive within phagocytes
            10. carotenoid pigment
            11. gold color on plates
            12. inactivates microbicidal efforts
            13. polysaccharide capsule
            14. most isolates have it
            15. ?inhibit phagocytosis
            16. antimicrobial resistance
            17. penicillin, methicillin
            18. resistance to drying
            19. allows bacteria to persist in environment
         4. epidemiology
            1. person-to-person spread
            2. skin infections, food poisoning
            3. MRSA
            4. hospital-associated
            5. resistant to all Abx except vancomycin, linezolid, daptomycin
            6. possess staphylococcal cassette chromosome mec Type I, II, III
            7. community-associated
            8. possess mec Type IV & PVL
            9. mostly skin & soft tissue infections
            10. emerging problem
         5. clinical manifestations
            1. skin & soft tissue
            2. more serious infections
            3. toxin associated diseases
            4. food poisoning
            5. TSS
            6. scalded skin syndrome
         6. diagnosis
            1. gram stains of pus
            2. cultures of blood, urine, exudates
         7. therapy
            1. nafcillin or oxacillin
            2. cephalosporins
            3. vancomycin for MRSA
            4. drainage
   3. Coagulase-negative
      1. S. epidermidis
         1. properties
            1. much resistance to Abx
            2. produce extracellular polysaccharide biofilm that helps w/adhesion
         2. epidemiology
            1. leading cause of infections with prosthetics
            2. usually hospital-acquired
            3. derive from pt's or caregivers flora
         3. clinical manifestations
            1. surgical wounds, prosthetics
         4. diagnosis
            1. culture of blood, CSF, exudate
            2. multiple positive specimens rule out contamination
         5. therapy
            1. vancomycin
            2. combo vanco & rifampin or gentamicin
      2. S.saprophyticus
         1. properties
            1. isolated from urine
         2. epidemiology
            1. 2nd leading cause of UTI in women
         3. diagnosis
            1. urine culture
            2. novobiocin-resistance differentiates from other coag-neg
         4. therapy
            1. more susceptible to Abx
            2. empiric UTI therapy (TMP-SMX, Amox, Ceph)
2. Streptococci
   1. Characteristics
      1. oval/spherical, gram pos, catalase neg
      2. effect on blood-enriched agar
         1. alpha hemolysis (green)
         2. beta (clear)
         3. gamma (no effect - non-hemolytic)
      3. Classification
         1. Lancefield groupings
            1. C-carbohydrate in cell wall
            2. groups A-T
         2. capsular antigens
   2. Group A Beta-Hemolytic Streptococci (S. pyogenes)
      1. properties & virulence factors
         1. hyaluronic capsule
            1. retards phagocytosis
         2. M proteins
            1. promote adherence
         3. Lipteichoic acid
            1. promotes attachment
         4. Protein F
            1. binds fibronectin
            2. attachment to nasopharyn. epithel cells
         5. Protein G
            1. cell surface protein that binds Fc of Ab
            2. interferes with immune recognition or complement activ.
         6. extracellular products
            1. rapid spread of infection w/o abscess formation
         7. Streptolysin O
            1. oxygen labile
            2. death of neutrophils, tissue cells, platelets in absence of O2
            3. inserts into membrane to form pores
         8. Streptolysin S
            1. cytotoxic activity in presence of O2
         9. Streptokinase
            1. activates plasminogen to plasmin
         10. DNA-ase
             1. lyses DNA
         11. hyaluronidase
             1. digests ground substance of CT
         12. pyrogenic exotoxins
             1. A, B, and C
             2. cause scarlet fever rash, TSS
         13. C5a peptidase
             1. degrades complement component C5a
      2. epidemiology
         1. pharyngitis, pyoderma
         2. person-to person by contact or droplet
      3. clinical manifestations
         1. pharyngitis and skin infections
         2. other uncommon but serious syndromes
         3. nonsuppurative sequelae
            1. rheumatic fever
            2. 3 wks after pharyngitis
            3. rheumatic heart disease
            4. ? cross-reacting Ab
            5. acute glomerulonephritis
            6. 10 days after pharyngitis, 21 days after skin infect.
            7. usually nephritogenic strains
            8. caused by Ag-Ab complexes deposited in glomeruli
      4. diagnosis
         1. culture of exudates, blood, fluids
         2. Ag detection tests
         3. serology
            1. anti-DNA-ase B Ab
            2. antihyaluronidase Ab
      5. therapy
         1. Penicillin G or V
         2. erythromycin, ceph, clinda, vanco
         3. prevents rheumatic fever but not glomerulonephritis
   3. Group B Streptococci (S. agalactiae)
      1. properties & virulence factors
         1. narrow zone of beta hemolysis
         2. polysaccharide capsules are virulence factors
         3. interfere w/phagocytosis and complement activation
         4. complement and Ab required for killing
      2. epidemiology
         1. normal fecal & vaginal flora
            1. may transmit to infant during birth if membranes rupture
         2. contamination of other sites by colonized sites
      3. clinical manifestations
         1. neonatal bacteremia
         2. pneumonia & meningitis
         3. gynecological infections
         4. skin & soft tissue infections
      4. Diagnosis
         1. culture of blood, CSF, synovial fluid, urine
         2. agglutination test to detect Ag in CSF
      5. therapy
         1. penicillin G or ampicillin; w/ aminoglycosides
         2. cephalosporins, vaco, carbapenems
   4. Group D Streptococci (Enterococci)
      1. properties & virulence factors
         1. non-hemolytic
         2. grow in 40% bile
         3. antimicrobial resistance
            1. intrinsic resistance
            2. Subtopic 1
            3. acquired resistance
      2. epidemiology
         1. normal flora of GI
         2. community-acquired
         3. hospital-acquired
            1. person-to-person
      3. clinical manifestations
         1. Streptococcus bovis
            1. endocarditis
         2. E. faecalis & E. faecium
            1. intra-abdominal
            2. surgical wound
      4. diagnosis
         1. cultures of blood, urine, pus
      5. therapy
         1. enterococcal
            1. ampicillin or vanco
         2. S. bovis
            1. penicillin
   5. Pneumococcus (Streptococcus pneumoniae)
      1. properties & virulence factors
         1. bullet/lancet shaped, diplococci
         2. alpha hemolysis
         3. virulence factors
            1. polysaccharide capsule
            2. interferes with phagocytosis & opsonization
            3. produces pneumolysin
            4. similar to streptolysin O
            5. injures cilia on resp epithel cells
            6. pneumococcal surface protein A
      2. epidemiology
         1. common colonies in nasopharynx
         2. person to person transmission
         3. leading cause of community acquired pneumonia
         4. vaccine
            1. recommended for infants
      3. clinical manifestations
         1. pneumonia
         2. otitis media
         3. sinusitis
         4. meningitis
      4. diagnosis
         1. direct examination of sputum
         2. cultures of sputum, blood, CSF
      5. therapy
         1. penicillin G (resistance increasing)
         2. erythro, ceph, clinda
         3. vanco for meningitis
   6. Viridans streptococci
      1. properties & virulence factors
         1. alpha hemolysis
         2. produce glucans
            1. enhance attachment to teeth and cardiac valves
      2. epidemiology
         1. infection from normal oral flora
      3. clinical manifestations
         1. infective endocarditis
      4. diagnosis
         1. culture of blood or pus
      5. therapy
         1. penicillin G; w/aminoglycosides
         2. ceph, erythro, vanco
3. Clostridium (C. perfringens)
   1. similar to necrotizing fasciitis caused by S. pyogenes
   2. properties & virulence factors
      1. large, encapsulated bacillus
      2. forms spores
      3. obligate anaerobe but aerotolerant
      4. toxins
         1. alpha toxin
            1. disrupts cell membrane
         2. theta toxin
            1. alters capillary permeability
            2. toxic to cardiac muscle
         3. enterotoxin
            1. diarrhea
   3. epidemiology
      1. found in soil, lg intestine, female genital tract
      2. infections following traumatic injuries
   4. clinical manifestations
      1. gas gangrene
         1. necrosis of muscle
         2. ferment carbs to produce gas
         3. systemic toxicity, fatal if untreated
      2. anaerobic cellulitis
         1. less toxic than gas gangrene
         2. infection of subcut around wounds
      3. clostridial endometritis
         1. unclean abortions
         2. hemolysis and renal failure
      4. clostridial food poisoning
   5. diagnosis
      1. clinical dx of syndrome
      2. x-rays for gas in tissue
      3. smears of swabs or aspirates
      4. cultures of wounds and blood
   6. therapy
      1. surgical debridement
      2. high dose penicillin G