Gram +

TPs 11/6/2009 File: 731dc765-2191-48a2-91d6-12a47996a80e.xls Sheet: Gram + Page 1 of 2 Gram-Positive Cocci Gram Stain Strep Pyogenes Strep aggalactiae Strep viridans Enterococcus faecalis Gp A Gp B + + + Gp D + Shape Coccus Pairs/Chains Coccus Pairs/Chains Coccus Pairs/Chains Coccus Pairs/Chains BHI BE Bile MSA NB NACL EsculinCatalase Hemolysis Growth Mannitol Pigment DNAse Coagulase Novabiasin Bacitracin (salt) Tolerance Beta Beta Alpha green Gamma no S R R R Growth Growth Coccus Irreg Clusters + + S Gold + + + + Coccus Irreg Clusters White S + + + Coccus Irreg Clusters + White R + + + Coccus Micrococcus Pairs, Luteus tetrads, 8s S Yellow + + + + Grapes of staph make champagne and champagne bubbles Catalase H2O2 - bubbles if positive Hemolysis blood agar; on catalase + organisms, clear zones around colonies indicate hemolysis Beta - complete lysis of cells, alpha - greening surrounding the colony, gamma - no change MSA growth 7.5% sodium chloride selects for Staph and against most other organisms Mannitol Differentiates by ability to ferment mannitol. Fermenters produce acid (pH indicator from red to yellow) Pigment on MSA DNAse after adding 1N HCl, HCl will cause a cloudy precipitate to develop if DNA is present in agar Zone of clearing indicates bacteria makes enzyme that degrades DNA Coagulase Inoculate tube of citrated rabbit plasma for 6 hours at 37C. Positive if forms have semi-solid clot at bottom of tube NB disc Bacitracin disc BHI broth + 6.5% NaCl Gently tap the tube to resuspend cells that may have settled out during the incubation. BE Tolerance If organism tolerates bile, it will grow; Group D strep hydrolyze esculin producing a black color Staph Aureus Staph Epidermidis Staph Saprophyticus + Strep Pyogenes Strep Aggalactiae Strep viridans Enterococcus faecalis Staph Aureus Staph Epidermidis Staph Saprophyticus Micrococcus Luteus Strept throat neonatal sepsis; spread from mother to child; 1/3 to 1/2 of babies acquiring this infection die Normally in the mouth - if it gets into the bloodstream, can cause endocarditis. Turns green on cutdown; alpha hemolysis - change in chemical nature of blood; loses its oxygen; chemically reduced. non-hemolytic - gamma hemolysis; relative of strep; hydrolyze esculin producing a black color; tolerates high salt content Local and systemic infections Opportunistic infections Nosocomial infections Urinary tract infection-mucosal Not generally responsible for causing disease in humans TPs 11/6/2009 File: 731dc765-2191-48a2-91d6-12a47996a80e.xls Sheet: Gram - Page 2 of 2 Results for the Enteric Bacilli Name Escherichia coli Klebsiella pneumoniae Enterobacter aerogenes Citrobacter freundii Salmonella enteritidis Morganella morganii Proteus mirabilis Serratia marcescens Pseudomonas aeruginosa MacConkey agar - mauve MacConkey red red red red colorless colorless colorless colorless + red colorless Hektoen agar orange orange orange orange (+ B?) green + B green + B green + B orange + red green TSI Y/Y Y/Y Y/Y Y/Y (B) R/Y (B) R/Y R/Y (B) R/Y R/R Tripton Broth Indole pos. neg. neg. neg. neg. pos. neg. neg. neg. MR pos. pos. neg. pos. pos. pos. pos. neg. neg. VP neg. neg. pos. neg. neg. neg. neg. pos. neg. Citrate neg. pos. pos. pos. pos. neg. pos. pos. pos. Urease neg. var. neg. neg. neg. pos. pos. neg. neg. SIM Motility var. neg. pos. pos. (B) pos. (B) pos. pos. (B) pos. pos. Comments very mucoid slightly mucoid may swarm red pigment green pigment Hektoen TSI Indole - Tripton Broth MR VP Citrate Urease Motility - SIM Enterobacter aerogenes Proteus mirabilis selective, gram-, rods grow; differential - red then lactose +, colorless then lactose Production of lactase - presence of acid (turns red), makes glucose + galactose Lactase is a disaccharide Bile salts select against Gram + H2S production detected by the production of a black precipitate in center of colonies of H2S positive organisms Y = acid, R = alkaline Y/Y ferment lactose and sucrose R/R non-fermenter - no color change R/Y ferments ONLY glucose Y/R only a goof, else NOT possible Enterobacter ferments so well that tip of slant will start to revert and turn red Add 5 drops of Kovac's - look for red ring at top; convert the amino acid tryptophan into indole 5 drops Methyl Red; detects production of significant amounts of acid from the fermentation of glucose; turns red if positive 20 drops of Leifson's Reagent; Rose red color in the presence of acetone production as a byproduct of glucose fermentation Voges-Proskauer test turns blue if positive; does or does not utilize citric acid as a carbon source turns pink if positive; if organism produces urease, it hydrolyzes urea into ammonium and CO2; ammonium raise pH B - hydrogen sulfide production; cloudy or turbid appearance throughout the culture tube Day 1-red; by day 2 loses its color because of excess growth TSI - looks black; if ferment less time, would see yellow at bottom B = black R = red Y = yellow