Gram-Positive Staphylococcus Characteristics, Pathogenesis, and Treatment

GRAM POSITIVE Staph -non motile/non spore -catalase+ -fac aerobe/anaerobe -mesophile, high salt culture -irregular clusters S. aureus ​ -pyogenic: abscess, furuncle/carbuncle, bullous impetigo -toxemia: SSS, TSST-1, food poisoning (SEA/SEB toxin) ​ Lab ID: golden on agar, ferment mannitol, B-hemolysis, coagulase+ -virulence: protein A, FnBP, hemolysin/leukocidin, hyaluronidase, staphylokinase -tx of penicillin resistant (PRSA): methicillin (not destroyed by B-lactamase) -MRSA: mec A gene of S. a codes for PBP2a, tx vancomycin -VRSA tx: linezolid S. epidermidis (prosthetic infection) ​ -virulence: capsule/slime layer (biofilm), novobiocin+, Y-hemolysis ​ -MSSE, tx nafcillin ​ -MRSE, tx vancomycin + rifampin S. saprophyticus (UTI- honeymoon cystitis) ​ -normal flora GI tract, vagina, perineum ​ -virulence: biofilm, urease (increase pH), novobiocin-, Y-hemolysis -tx: TMP-SMX (block folic acid bacteria need to grow) Strep -non motile/non spore -catalase-fac anaerobe -long short/chain -strep pyrogenic exotoxin (SpeA/SpeB, B leads hemolysis) -Brown grouping: a, B, y hemolysis -lancefield groups: group A, B, D-- based on carb cell wall S. pyogene (GAS, B-hemolysis) ​ -virulence: hyaluronic acid capsule, M protein, streptolysin O and S -invasive: streptokinase (dissolve blood clot for bacteria spread), streptodornase (DNase), C5a peptidase, protein F, hyaluronidase -suppurative: pharyngitis, soft tissue infections -autoimmune: rheumatic fever, glomerulonephritis (cause hematuria, proteinuria) -scarlet fever, impetigo (S. pyoderma), erysipelas, necrotizing fasciitis, puerperal fever ​ -lab ID: bacitracin sensitive, PYR+, ASO titer S. agalactiae (GBS, B-hemolysis) ​ -neonatal: meningitis, pneumonia, bacteremia (tx intrapartum penicillin) ​ -lab ID: bacitracin resistant, CAMP+ (arrowhead), hippurate (purple) S. bovis + enterococcus faecalis (GDS, Y-hemolysis) ​ -colorectal cancer (S. bovis) ​ -lab ID: gram stain, 6.5% salt inherently vancomycin resistant S. pneumoniae (no group, a-hemolysis) ​ -antigenic capsule, pneumolysin (attack lung tissue, degrade hemoglobin), IgA protease ​ ​ ​ -MOPS/OPSI -tx abx, prevent w/ vax (prevnar/pneumovax) -lab ID: green around colony, optochin sensitive, quellung rxn (capsular swelling test, omnisera) viridans strep (no group, a-hemolysis) ​ -S. Mutans: c, e, f serotype = caries​ ​ ​ -survive in acid by glycolysis, repair enzymes, long fatty acid chains (unsaturated) -adhesin AgI and AgII, glucan binding protein ​ -S. Sanguinis = subacute bacterial endocarditis Bacillus -aerobic/spore B. anthracis ​ -anthrax (woolsorter’s disease) ​ -capsule is poly-D-glutamic acid → establish infection ​ -edema/lethal toxins cleave protective antigen w/ furin ​ ​ -lethal factor cleave MAPKK ​ ​ -edema factor increase cAMP ​ -virulence: pX01 toxin plasmid, pX02 capsule plasmid ​ -ames/sterne strain used for vax ​ -lab ID: non motile, non hemolytic, fast growth B. cereus ​ -heat stable enterotoxin, cereolysin (degrade RBC) + PLC (lecithinase) ​ -food poisoning, gastroenteritis: emetic (HS) from rice and diarrheal from meat/veggies (HL) ​ -tx: abx, NO penicillin/cephalosporin (B- lactamase) ​ -lab ID: motile, hemolytic, use citrate Clostridium -soil, water, sewage -anaerobic/spore -lab ID: enzymatic digestion egg yolk agar plate C. tetani ​ -virulence: tetanospasmin (HL neurotoxin), blocks glycine → spasms ​ tetanolysin (HS hemolysin) ​ -tetanus symptoms: lockjaw, fixed smile, seizure, auditory hyperacuity, pain neck/jaw C. botulinum ​ -soil, canned food ​ -nerve toxin ​ -blurred vision, difficulty swallowing, flaccid paralysis -virulence: type A, B, E (HL neurotoxin), blocks Ach @ NMJ -botox is type A C. perfringens ​ -gas gangrene/myonecrosis: tissue damage (blood flow stops), fermenting muscle and putrefying proteins ​ -virulence: exotoxin like protease, lipase, collagenase ​ -tx: amputation/hyperbaric oxygen chamber, abx not recc C. difficile ​ -PC (pseudomembranous colitis) -consequence of elimination of normal intestinal flora bc abx therapy -abdominal pain, watery diarrhea ​ -virulence: exotoxin A (enterotoxin) and B (cytotoxin) ​ -lab ID: exotoxin A (immunoassay) and B (cytotoxicity assay)