MMSC 428 Final Exam questions and answers well illustrated.

MMSC 428 Final Exam questions and answers well illustrated. Staphylococcus aureus - correct answers.-gram positive cocci in cluster -the most clinically significant staph, important cause of hospital acquired infections -produces protein A, extracellular enzymes and exotoxins -facultative anaerobe -medium sized B-hemolytic colonies -halotonic -mannitol fermentation + -catalase + -*coagulase +* -serological test for TSST-1 and DNA probes are good for detection -usually resistant to penicillin and methicillin staphylococcus aureus clinical manifestations - correct answers.-furuncle: large, raised suppurative dome shaped abscess (boil) due to infection of Staph aureus in oil gland or hair follicle -carbuncle: furuncle lesion progresses deeper and causes more invasive infection in lower skin, causing systematic symptoms and fever -impetigo: bullous (5 mm) pustules filled with fluid surrounded by erythema typically seen on the face of children -cellulitis: infection of connective tissue that leads to inflammation -staphylococcal scalded skin syndrome (SSS): exfoliative dermatitis caused by infection with staph aureus that releases exfoliatin toxin, leading to red, peeling skin that resembles 2nd degree burn (infants and neonates mainly) -toxic shock syndrome (TSS): staph aureus infection releases TSST-1 super antigen and enterotoxin B to cause systemic symptoms (fever, kidney and liver damage, vomiting, diarrhea, muscle ache and rash) that can progress to hypotension and shock (menstrual and nonmenstrual forms) -intoxication food poisoning: enterotoxins A, D and B contaminate food and leads to severe projectile vomitting and diarrhea -nosicomial infections: wound infection, osteomyelitis, biofilm on body implant -head and neck infections in children antibiotic resistant staphylococcus aureus - correct answers.-MRSA (methicillin resistant) -VISA (vancomycin intermediate) staphylcoccus lugdunensis - correct answers.-gram positive staphylococci -very virulent and clinically significant, causes similar infections to Staph aureus, just seen less often -*ODC +* -coagulase - -PYR + -mannitol - -nonhemolytic -oxacillin resistant -causes skin abscesses, meningitis, septicemia, septic shock and UTI -causes very aggressive and fatal infectious endocarditis staphyloccocus saprophyticus - correct answers.-gram positive staphylococcci -*coagulase, clumping factor, PYR and ODC -* -nonhemolytic -common cause of UTI in females, even a small amount in the urine is significant micrococcus - correct answers.-gram positive cocci -used to be grouped with staph but are less clinically significant and lab characteristics are different -*lysostaphin resistant* -bacitracin sensitive -glucose fermentation - -modified oxidase (cytochrome C oxidase) + staphylcocci characteristics - correct answers.-gram positive cocci that grow in clusters -*catalase +* (good to differentiate from step) -nonmotile, lack flagella -facultative anaerobes, prefer aerobic environment -lysostaphin sensitive -glucose fermentation + -modified oxidase + -bacitracin resistant -important causes of hospital acquired infections streptococcus pyogenes (group A streptococcus) - correct answers.-gram positive cocci in chains -catalase - -lancefield group A cell wall antigens -modified oxidase - -fastidious, require additional nutrients from blood to be cultured -B-hemolytic -streptolysin O causes B-hemolysis in anaerobic conditions -streptolysin S causes B-hemolysis in aerobic conditions -*PYR +* -small, transparent, dry colonies -bacitracin sensitive -produces M protein, hyaluronic acid capsule, pilli, streptodornoase and streptokinase virulence factors -treated with penicillins culture, antigen detection assays or serology are used for diagnosis streptococcous pyogenes (group A strep) clinical manifestations - correct answers.-pharyngitis: "strep throat" seen mainly in children from 5-15 with sore throat, malaise, fever, headache, nausea/ vomitting (adults have M protein antibodies and usually are not infected) -scarlet fever: untreated strep throat causes release of erythrogenic toxins into blood that breaks own RBCs and causes rash, damage to blood vessels, "strawberry tongue" (not common in developed countries where people get treated) -impetigo: dermal infection leads to formation of non-bullous (5 mm) lesions that leak and then crust over -erysipelas: infection of dermis and subcutaneous tissue that leads to erythmatous, swollen, painful inflamed lesions on the skin (mainly elderly individuals) -necrotizing fasciitis: life threatening and invasive infection that begins as a skin infection and rapidly progressing inflammation and necrosis of skin, subcutanous fat and fascia membrane progress -purpural fever: infection of neonate that is innoculated with Strep pyogenes from the vaginal mucosa during birth causing bacteremia, and sepsis (not common anymore) -streptococcal toxic shock syndrome: initial cold symptoms that progress to flu-like symptoms and eventually cause a highly fatal pneumonia -sinusitis with otitis media with effusion (OME): ear infection that is more common in children due to lateral eustachian tube streptococcus pyogenes (group A strep) culture - correct answers.-obtain throat swab -SBA can be used (normal biota from throat can overpopulate) -selective strep agar (SSA) is best post-streptococcal sequealae - correct e-mediated conditions that follow infections with streptococcus pyogenes (group A strep) -acute glomerulonephritis: infection of the skin leads to type 3 hypersensitivity reaction when large immune complexes form in blood and get trapped in the glomerulus, body triggers immune response to clear out immune complexes and damages the kidney -acute rheumatic fever (ARF): infection of the throat (pharyngitis) is not treated and body produces antigens against M proteins that cross react with antigens on the heart, leading to type 1 hypersensitivity reaction that causes progressive valve damage -both can be treated with penicillin streptococcus algalactaiae (group B strep) - correct answers.-gram positive streptococcus -aerotolerant anaerobe -group B lancefield cell wall antigens -CAMP test + (enhanced hemolysis) -hippurate hydrolysis + -produces carbohydrate super antigen (similar to endotoxin/ LPS) and sialic acid capsule -part of normal biota, found in vaginal mucosa