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Staphylococcal Infections. Godwin Tse LA-TRAP Summer 2011. Staphylococcus. from Greek word staphlye and kokkos , “bunches of grapes” Gram positive bacteria Round (coccus), found in clusters Genus can be divided the ability to produce coagulase. Coagulase positive S. aureus
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Staphylococcal Infections Godwin Tse LA-TRAP Summer 2011
Staphylococcus • from Greek word staphlye and kokkos, “bunches of grapes” • Gram positive bacteria • Round (coccus), found in clusters • Genus can be divided the ability to produce coagulase
Coagulase positive • S. aureus • S. hyicus-intermedius group (5 other strains) • S. aureus • Part of normal flora, can be found in nose and skin • 80% of population in the US are colonized at some point, 20-30% persistently
Pathophysiology • Tissue invasion • Transmission • Formation of abscess • Transport via blood • Toxin-mediated disease • Consumption of contaminated food • Caused by enterotoxins
Food poisoning • toxic shock syndrome • gastroenteritis • Scalded skin syndrome Skin infection • impetigo • cellulitis • bacteremia/sepsis • staphyococcal pneumonia • endocarditis • osteomyelitis
Signs and Symptoms • Abscess, boils • Redness, swelling, lesions • Pus • High fevers, chills, low BP • Food poisoning: nausea, vomiting, diarrhea, dehydration withing 1-6 hrs
Risk factors • Newborn infants • Breastfeeding women • Weakened immune systems • Skin injuries/disorders • Chronic conditions such as diabetes, cancer, vascular disease, lung disease • Presence of intravenous catheters or surgical incisions
Tests • Blood culture • Culture from the infected site • Gram stain and culture of the fluid • Sputum culture • Urine culture
Treatment • Drainage of infection • Antibiotics • Pencillins • Cephalosporins • Clindamycin • Vancomycin
MRSA • Methicillin resistent Staphylococcus aureus • HA-MRSA • Affects the very sick, elderly, and those with an open wound such as a bedsore or catheter • CA-MRSA • Associated with recent antibiotic use, active skin diseases/injuries, poor hygiene, crowded settings • Accounts for 12% of MRSA infections (from CDC)
Coagulase negative staphylococci • S. epidermidis • Creates biofilms • Occurs on intravenous catheters or surgical implants • Antibiotics not as effective due to impaired diffusion caused by surface proteins • Most effective treatment is to replace catheter or implant
Prevention • Proper hygiene when attending to skin wounds • Avoid skin contact with infected individuals • Safe food practices Source
References • http://www.medicinenet.com/staph_infection/ • http://emedicine.medscape.com/article/971358 • http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0004520/ • http://en.wikipedia.org/wiki/Staphylococcal_infection • http://www.cedars-sinai.edu/Patients/Quality-Measures/Preventing-Hospital-Acquired-Infections/Preventing-Bloodstream-Infections-by-Methicillin-Resistant-Staphylococcus-aureus-MRSA.aspx • http://www.cdc.gov/