Non-spore forming Facultatively anaerobes Glucose fermenters Oxidase (-) (exc. Plesiomonas) Catalase (+) (exc. Shigella dysenteriae) Commensal flora except Salmonella, Shigella, Yersinia (true pathogen) Nonencapsulated except (Klebsiella & Enterobacter) E. coli Primary marker for fecal contamination in water Disease Association Most common cause of nosocomial infections E. coli BIOTYPES Meningitis/sepsis-associated E. coli Infection Meningitis Virulence Factor …
Gram (+) Branching Partially acid-fast Nocardia Characteristics Beaded appearance Strictly aerobic Presence of DAP Produces Nocobactin – ironchelating compound Urease (+) Disease association Cutaneous infection Actinomycotic mycetoma Nocardia brasiliensis – most common cause of cutaneous infection and actinomycotic mycetoma. Nocardia asteroides – causes pulmonary infection Organism Casein Hydrolysis Nocardia brasilisiensis + Nocardia asteroides – Rhodococcus …
gram variable / gram (-) beta-hemolytic (HBT agar) / nonhemolytic (BAP) causes bacterial vaginosis Causes Bacterial Vaginosis Gardnerella vaginalis Prevotella spp. Peptostreptococcus spp. Porphyromonas spp. Mobiluncus spp. Mycoplasma hominis NUGENT SCORING SYSTEM – most accurate means of diagnosing bacterial vaginosis than culture NUGENT SCORING SYSTEM Lactobacillus morphotypes (boxy, gram (+) bacilli Gardnerella & Bacteroides (pleomorphic, …
Gram (+) bacilli Catalase (-) Non-branching H2S (+) in TSI Erysipelothrix rhusiopathiae Disease Association Erysipeloid bacteremia cutaneous infection Colony Appearance on BAP Large, rough, or small, smooth and translucent Shows alpha-hemolysis after prolonged incubation Identification Test-tube brush-like pattern in gelatin stab culture.
Gram (+) bacilli Catalase (+) Non-spore formin Non-branching Corynebacterium diphtheriae Virulence Factors Diptheria Toxin blocks protein synthesis causes demyelinating peripheral neuritis Bacteria is infected by lysogenic Betaphage TONSIL / PHARYNX – most common site of infection. Disease Association Respiratory Diphtheria – development of pseudomembrane (gray to white) Cutaneous Diphtheria – non healing ulcers (dirty gray) …
Aerobic and facultatively anaerobic Gram (+) Catalase (+) Spore-forming bacilli B. anthracis characteristics non-motile “bamboo rod” appearance Produces endospores Appearance in 5% SBA: Medusa head Ground glass appearance Beaten egg whites In MHA: String of Pearls Virulence factors Protective Antigen – facilitates transport of two other protein into the cell. Edema factor (adenylate cyclase) – …
Gram (+) cocci In pairs or chains Aerotolerant anaerobes Some are capnophilic Characteristics COLONY Usually small and transparent CATEGORIES OF NECROTIZING FASCIITIS Type Description 1 Polymicrobial infection (aerobic & anaerobic) 2 Consist of Group A Streptococci 3 Clostridial myonecrosis Saltwater Necrotizing Fasciitis Caused by Vibrio spp Organism Lancefield Smith and Brown’s S. pyogenes A Beta …
Gram (+) cocci Facultatively anaerobes (except for S. saccharolyticus – OBLIGATE ANAEROBE) In tetrads or in clusters Catalase (+) Oxidase (+) Non-motile Grows in 7.5 – 10% NaCl Characteristics COLONY Produced after 18-24 hrs. Medium-sized (4-8 um) COLORS: Cream-colored White Rarely light gold “buttery-looking” HUMAN NARIS (NOSTRILS) – PRIMARY RESERVOIR FOR STAPHYLOCOCCI S. aureus Disease …
AST STANDARDIZATION McFarland Turbidity Standards 1% H2SO4 1.175% BaCl2 0.5 McFarland – most commonly used Growth Medium pH – 7.2 – 7.4 cation concentration blood and serum components thymidine content Testing Medium for Different Organism Organism Media Incubation Notes Enterobacteriace ae P. aeruginosa Enterococci Mueller Hinton 35°C; air 16 – 20 hrs. Staphylococi MH …
POLYMERASE CHAIN REACTION DENATURATION – 94 – 95 degree Celsius (15 – 30 secs) For dsDNA separation PRIMER ANNEALING – 45 – 65 degree Celsius (30 secs. – 2 mins.) Anneals primer to target DNA PRIMER EXTENSION – 68 – 72 degree Celsius Synthesis of new strands of DNA PCR COMPONENTS Template DNA – target …
