Staphylococcus And Other Flashcards
Endogenous strain: Sterile urinary tract, notably in young, sexually active female
Staphylococcus saprophyticus
Endogenous strain: sterile site by traumatic introduction (e.g., surgical wound or microabrasions
Staphylococcus aureus
Endogenous strain: sterile site, by implantation of medical devices (e.g. shunts, prosthetic devices)
Staphylococcus epidermidis
Produce polysaccharide capsule (inhibits phagocytosis)
S. aureus and S. epidermidis
Disrupts smooth muscle in blood vessels. Toxic to erythrocytes, leukocytes, hepatocytes, and platelets
Alpha toxin
Work in conjunction with alpha toxin. Heat-labile sphingomyelinase which catalyzes hydrolysis of membrane phospholipids resulting in cell lysis.
Beta toxin
Cytolytic to erythrocytes. Produced by S. haemolyticus, S. epidermidis, S. aureus (SHEA)
Delta toxin
Associated with Panton-Valentine Leukocidin (PVL)
Gamma toxin
Resistant to hydrolysis by the gastric and intestinal enzymes
Heat-stable enterotoxin
Scalded skin syndrome (Ritter disease), pemphigus neonatorum, food poisoning, folliculitis, furuncles, and carbuncles
S. aureus
Virulence factors: polysaccharide capsule, peptidoglycan, protein A, heat-stable TSST-1
S. aureus
Virulence factor: exopolysaccharide “slime” or biofilm, delta toxin
S. epidermidis
Endocarditis involving prosthetic cardiac valves; infection at intravascular catheter sites, other infections associated with CSF shunts, prosthetic joints, vascular grafts, post surgical ocular infections
S. epidermidis
Extremely low virulence. Rarely cause infections in humans; implications in otitis external and otitis media
Micrococcus, etc.
Recover aerobic and anaerobic bacteria
Amies transport media
Recover aerobic and anaerobic bacteria; charcoal neutralized bacterial toxins
Amies with charcoal transport media
Recovers anaerobes and micro aerobic
Anaerobic transport media
Recover enteric bacteria
Cary-Blair
Recover gastrointestinal parasites; acceptable for immunoassays
Formalin (5% -10%); polyvinyl alcohol (PVA); sodium-acetate-acetic acid formali (SAF); Total-fix; Eco-fix
Media of choice for Staphylococci, Micrococci, related organisms
BAP, Thioglycollate, Dextrose, Brain-Heart infusion broth
Resembles S. lugdunensis in 5% SBA
Staphylococcus wameri
Beta hemolytic in 5% SBA
S. aureus, S. haemolyticus, S. lugdunensis
Wide variety of pigments (white, tan, yellow, orange, pink) in SBA
Micrococcus spp., and related organisms
Separate S. aureus from other species collectively referred to as coagulase-negative streptococci.
Coagulase production
Novobiocin resistant with inhibition zone diameter of <10mm
Staphylococcus saprophyticus
Used to discern between methicillin-sensitive S. aureus (MSSA) and MRSA
Matrix- Assisted Desorption Ionization Time of Flight
Selective and differential for identification of MRSA
CHROMagar
MRSA colonies in CHROMagar
Mauve color
Visible growth @ 35C in CO2 or ambient air within 24 hours of inoculation
5% sheep blood and chocolate agars
Require at least 48-72 hrs before growth is detected
MSA and other selective media
Requires storage and incubation in dark for best results
CHROMagar
