Non-Fermentative Gram-Negative Rods
Pseudomonas sppGram Stain
Gram-PositiveGram-Negative
Cocci
Bacilli
Cocci
Bacilli
Classification of Bacteria
Characters of Pseudomonas
Gram-negative bacilli belonging to Pseudomonadaceae Motile by means of a single polar flagellum. Non spore forming non Capsulated "Polysaccharide capsule" Aerobic Breakdown glucose by oxidation i.e. Oxidative Oxidase and catalase positive It has very simple nutritional requirements i.e. non fastidious The most important pathogenic organism is Ps. aeruginosa Optimum temperature is 37 C, and it is able to grow at 42 C It is resistant to high concentrations of salts, dyes, weak antiseptics, and many antibiotics Common inhabitants of soil, water, GITe`ewePs. aeruginosa is opportunistic pathogen and associated with a variety of infections including: Urinary tract infections Wound and burn with blue green pus Respiratory system infections (Pneumonia) Eye infection and may lead to blindness Ear infection (external ear or otitis media) Meningitis A variety of systemic infections Ps. aeruginosa produce two types of soluble pigments: Pyoverdin or fluorscein: It is yellow-green pigment and fluorescent Pyocyanin: It is a blue-green pigment and non-fluorescent
Identification of Ps. aeruginosa
Laboratory diagnosis Specimen: Urine, pus, sputum, CSF, blood, skin swap according to the type of infection Microscopical Examination Gram Stain: Gram-negative rods Motility Test: Hanging Drop Techniques Semisolid agar medium
Motile
Cultural Characteristics
On Nutrient agar: Colonies are surrounded by bluish green colorationOn selective media "Cetermide" Pigments are more obvious On Blood agar -hemolytic coloniesOn MacConkey agar Pale yellow colonies i.e. non lactose fermentersPs. aeruginosa able to grow at 42 C for 3 daysCultural Characteristics
Gram Stain of PseudomonasPs. aeruginosa on Nutrient agar
Ps. aeruginosa on cetrimide agar
Biochemical Reactions
Oxidase positive Breakdown glucose oxdatively Nitrate Reductase negative Gelatinase positive Utilize CitrateOxidase Test: Principal
Oxidase ReagentCytochrome Oxidase
Indophenol
Play role in aerobic respiration
Pseudomonas Vibrio
Alternative substrate for Cytochrome
Tetramethyl-P-Pheneylenediamine Colorless
Purple color
Oxidize the reagent from colorless to purple color
Negative
PositiveMethod: hold a piece of the oxidase test paper with forceps and touch onto an area of heavy growth Use platinum loop (not used nichrome) or wood stick Results Color change to purple within: 10 seconds = positive 10 - 60 seconds = delayed positive >60 seconds = negative