Staphylococcus Aureus + Epidermis

Gram + (Pt 1)

Microbiota

Staphylococcal bacteria are pathological but are also part of the __ for many of us

Positive, facultative, capsule, biofilm, grape

Staphylococcus Genus

• Gram (+) cocci, catalase __, non spore-forming, non-motile

• __ anaerobes - can survive in variety of temperature conditions and salt solutions

• Most have polysaccharide __; some species also form __ (i.e. growth in catheters, prosthetics)

• “__-like clusters”

Positive, white, yellow, beta, everywhere

Staph Aureus

• Coagulase __, catalase positive

• Gram strains - __ or __ colonies; must show __-hemolysis

• Found __ in the environment

• Habitat - mammalian body surfaces, normal microbiota

Cyto, exfoliative, superantigen, entero

• Staph A source of infection is primarily endogenous (autoinfection from own microbiota)

  • Possible toxins produced  - __toxins (alpha toxin), __ toxin, __ toxin, __toxins (GI acting)

Alpha toxin

Protein exotoxin produced by most disease strains of S. aureus

Pores, K+/Na+/Ca2+, lysis, RBCs

Alpha toxin

• Binds to cell membranes, aggregates and forms __

• Disrupts __/__/__ (ions) balance and other small molecules

• Osmotic swelling and __ of cell

• Affects __, leukocytes, platelets

Exfoliative toxin

Staph a. toxin acts as enzyme and breaks down cell-cell adhesion molecules and eventually junctions

SSSS, bullous impetigo

Outcomes from exfoliative toxin of staph a (2 diseases)

Superantigen, hypo, rash, vomiting, diarrhea

Toxic Shock Syndrome Toxin (TSST-1) - Staph A

• __ that activates non-specific adaptive immune system “overresponse”

• Severe systemic symptoms - __tension, fever, __, __ and __ (2x GI)

Capsule, protein A

Anti-phagocytic virulence factors (2) of Staph A

• __, and __ on surface of Staph A bacteria

Protein A

Binds Fc portion of IgG molecules leading to dysfunctional antibodies and no phagocytosis (staph A)

Hyaluronidase

Breaks down connective tissues (tissue invading factor)

Catalase

Neutralizes components of phagolysosome (tissue invading factor)

Coagulase

Promotes blood clotting leading to abscesses, protect bacteria against phagocytosis (tissue invading factor)

Impetigo

Localized skin infection of superficial epidermis with pus-filled vesicles (Staph A disease)

Folliculitis

Localized skin infection of hair follicle with pus-filled vesicles (Staph A disease)

Furuncles

Large painful pus-filled boils (Staph A disease)

Carbuncles

Furuncles that coalesce and invade subcutaneous tissue, most serious (Staph A disease)

Endocarditis

Infection of endothelial lining of heart (Staph A disease)

Pneumonia

Abscess formation in lungs, from bacteremia or aspiration (Staph A disease)

Septic arthritis

Painful joint with pus in joint space (Staph A disease)

TSST, SSS

Systemic diseases of Staph A from toxins released by infecting strain (i.e. __, __ diseases)

Culture, stain, antibx, MRSA

Diagnosis and treatment of S. aureus infections

• Overnight __ of patient samples and gram __

• Treatment - __, issues with antibiotic resistance (i.e. __-disease)

Methicillin resistant Staph aureus, Beta-lactam, mecA, vancomycin

• __ __ __ __ (MRSA)

  • Most staph from community and hospital are resistant to all __-__ antibiotics

  • Resistance mechanism: __ gene

    • Transpeptidases become resistant to penicillin spectrum

• MRSA remain mostly sensitive to __ (antibx)

Pre-formed, room, 4, 24, heat stable

Toxin-mediated disease by S. aureus

• Ingestion of a __-__ toxin produced by bacteria → contaminates a food product 

• Food needs to be at __ temperature

• Incubation time is _ hours - sx vomiting, abd cramps, diarrhea

  • Recovery within __ hours

• Staph A food Toxin is __-__ (property), no effect with warmth

Negative, alpha, antigen, adhesins

Staphylococcus Epidermis

• Coagulase __, catalase-positive

• Do NOT produce __-toxin, exfoliatin, or super__ toxins

• Have __ (protein) instead, and may form biofilms

Commensals, opportunistic, biofilm

Staph Epidermis

• Normal __ of skin - component of microbiota

  • Most abundant in axillae, head, nares

• Best considered an __ pathogen → Disease in immunocompromised

• Cause UTIs, __ infections, implanted device infections