Med Micro: PPT 5 Staphylococcus aureus

eubacteria

main group associated with infections of man

endospore

G+ dormant forms; no metabolic activity; heat resistant; resistant to drying, chemical agents, radiation, UV exposure; some over 150 years old; sterilization techniques kill by forcing water into

capsule

made of sugars coating bacteria; prevents phagocytosis; function as adhesion; tough polysaccharide film; holds water to prevent drying

coagulase positive

Staphylococcus aureus

coagulase negative

all other staphylocccus

Staphylococcus aureus

skin, bone/joint, heart, lungs, TSS, food poisoning, opportunnistic

Staphylococcus epidermidis

surgical wounds, bacteremia, endocarditis, UTIs, opprotunisitc on medical devices

Staphylococcus haemolyticus

UTIs; opprotunistic

Staphylococcus lugdunesis

endocarditis, arthritis, bacteremia, UTIs - opportunistic

Staphylococcus saprophyticus

bacteremia, endocarditis, bone/joint, UTI, wound, opportunistic

nose, throat, moist skin areas, groin, armpit

where S. aureus is normally found to colonize in the human body

CA-MRSA

community aquired; tend to not have as many virulent strains

HA-MRSA

hospital aquired; tend to have many virulent strains; antibiotic resistant

abscess formation

primary form of S. aureus; primarily in the skin, but can form anywhere on the body; usually at the end of a blood vessel

furuncle

same as a boil; localized skin infection including hair follicle and surrounding tissue

folliculitis

inflammation of hair follicles causing raised, itchy, and pus-filled bumps on the skin

carbucnle

deeper than furuncle, or fused furuncles

impetigo

lesions on the skin that are red, “honey-crusted”; usually not painful; sometimes blistering; can also be caused by Group A Strep

osteomyelitis

infection of bone and bone marrow; usually sudden onset with localized pain and fever; 6-8 weeks of antibiotics using Rifampin as 2nd antibiotic

endocarditis

inflammation of the heart valve; often lead to scarring of the heart valve

acute bacterial endocarditis

frequent cause of bacteremia, endocarditis, osteomyelitis, septic arthritis

pneumonia

aspiration pneumonia in young/old immunocompromised lungs; inflammation of the alveoli

empyema

pus between the lung anf chest wall, in the pleural space; found in 10% of patients with pneumonia

scalded skin syndrome

bacteremia leads to disease, skin culture negative, epidermis peels off in sheets due to exotoxin; recovery in 7-10 days with no scarring

SSSS

Staphylococcal scalded skin syndrome

bullous impetigo

localized SSSS; culture positive superficial skin blisters; highly communicable

toxic shock syndrome

acute onset; septic shock; caused by extended bacterial growth in anaerobic environment; absorbs magnesium which activates toxin

septic arthitis

erythematous joint, purulent material on drainage; can be caused by S. aureus or Neisseria gonorrheae

enterotoxin

heat stable causing diarrhea and vomiting; absorbed by mucosa, enter blood, and circulates back to intestines to cause tissue damage and food poisoning symptoms

staphylococcal enterocolitis

inflammation of gastrointestinal tract; broad spectrum antibiotics can lead to this disease

native valve endocarditis

streptococci > Staphylococcus lugdunensis > Staphylococcus epidermidis

artificial valve endocarditis

slow progressive infection; symptoms develop over a year; requires prompt surgical intervention

intravascular catheters and shunts

persistant bacteremia. occasionally glomerulonephritis

prosthetic joint infections

localized pain anf mechanical failure; replacement, antibiotics, higher failure rate on new replacement

UTIs

caused by Staphylococcus saprophyticus in young sexually active women; dysuria and pyuria

methicillin, vancomycin, mupirocin

anitbiotics used against Staph infections

MRSA

methicillin resistant Staphylococcus aureus; contact procautions with gloves, maskm and gown