staphylococci

• G(+)
• lack endospores
• non motile
• spherical shape
• catalase (+/-)
• facultative anerobes
• grows in high salt concentration
• grows in temp 18-40C

• opportunistic infections
• nosocomial infections

coagulase (+)

• s. epidermidis
• s. saprophyticus
• s. lugdunesis
• s. haemolyticus

• toxin mediated: food poisoning, scalded skin syndrome, toxic shock
• cutaneous: carbuncles, folliculitis, impetigo
• other: bacteremia, endocarditis, pneumonia, empyema osteomyelitis

• bacteremia
• endocarditis
• surgical wounds
• UTI
• invasive medical equipment

• UTI
• opportunistic infections

• endocarditis
• arthritis
• bacteremia
• opportunistic infections
• UTI

• bacteremia
• endocarditis
• bone and joint infections
• UTI
• opportunistic infections

• contains capsules: repeating units of polysaccharides
• most have biofilms/slimlayer: amalgam of monosaccharides. attributes to binding on medical equipment

penicillin binding proteins (PBPs)

MecA gene, which gives some strains antibiotic resistance (methicillin, penicilin, cephalosporins)

• directs cell division
• shape molecular surface properties
• mediates biofilm formation
• serve as phage receptors
• mediates interactions with host receptors
• controls susceptibility/resistance to anitbiotics
• ** binds to fibronectin in connective tissue

• micobial surface components recognizing adhesive matrix molecule
• are virulence factors, and proteins bound to peptidoglycan

• bound coagulase
• elastin binding protein
• collagen binding protein

• binds directly to firbinogen and converts it to fibrin. 
• Causes clots to form and staph cells to aggregate. Clots prevent detection by immune cells

help bacterial cells bind to elastin and collagen

adhesion proteins increase in expression

tissue invasion and hydrolytic enzymes increase

innate immunity system suppress gene expression, allowing for staphylococcal colonization at low densities

• coagulase
• capsule 
• slime layer
• protein A

converts fibrinogen --> insoluble fibrin

• is released by cells and interacts with prothrombin to produce staphylothrombin complex
• converts firbinogen to insoluble firbin

protects staphylocci from phagocytosis

s. aureus

protects against antibody mediate immune clearance

• hyaluronidase
• fibrinolysin
• lipase
• coagulase
• **s. aureus produces DNAse***

cytoxins that damage cells and tissues by disrupting cell membranes and causing cell lysis

• alpha toxin
• beta toxin
• gamma toxin
• leukocidin

disrupts smooth muscle in blood cells, forming pores and causing cell lyses

catalyzes hydrolysis of membrane phospholipids and causes cell lysis

causes pore formation and lysis in neutrophils and macrophages

• contributes to a wide spectrum of cytolytic activity, affects all cell types
• non specific
• acts as a detergent

delta toxin

• break intercellular briidges in stratum granulosum epidermis
• not associated with cytolysis or inflammation

• enterotoxins: food poisoning, resistant to digestive enzyme
• toxic shock syndrom toxin-1 (TSST-1): an exotoxin that penetrates mucosal barriers away from area of inoculation

• CNS found in skin
• s. aureus and CNS are found in oropharynx, nasopharynx, GI tract, and urogenital tract

• skin blisters followed by desquamation of epithelium (peeling/shredding) of skin
• blisters do not contain any organism - indicating toxin mediated pathology
• no scarring
• produces bullous impetigo

young children or babies because antibody mediated immunity against the toxin develops after infection

• children: low mortality, death is due to secondary bacterial infection
• adults: high (60%), usually affects immunocompromised

• large blisters of localized manifestation of SSSS infection. 
• blisters contain infectious organisms
• affects mainly children
• rarely fatal

• human carrier
• someone does not wash hands or sneezing on foods

• exotoxins
• heating and cooking does not inactivate heat stable toxins, but kills the organism

4 hours and lasts for 24 hours

s. aureus

localized infections release TSST-1 into blood causing fever, hypotension, rash, organ failure, desquamation of skin

• impetigo
• folliculitis
• carbuncles
• wound infections

• superficial infection, affects children
• small red spot devlopes into pus and becomes crusted

• infection of hair follicles which may progress into large boils (faruncles)
• if infects the eye, called stye

• a giant red faruncle (boil) that extends into deeper subcutaneous tissue.
• chills and fever

• infection of heart lining and values
• mortality rate of 50%

• pneumonia
• empyema: pus in pleural cavity

• when s. aureus spreads from blood and infects long bones, joints, hips.
• s. aureus is primary cause of septic arthritis

• endocarditis of heart valves
• catheter and shunt infections (50% occurance)
• prosthetic joint infections

• s. saprophyticus
• in sexually active women

• (+)
• ferments mannitol

b-lactam

incision and drainage of abscesses, then antibiotic treatment

• vancomycin: resistant strains are increasingly common
• daptomycin, tigecyclin, or linezolid