Pseudomonas and Related Organisms (Nonfermenters) Flashcards
Module 2
What are the general characteristics of nonfermenters?
they are aerobic, non-spore forming, gram-negative bacilli that either do not utilize carbs as sources of energy or degrade carbs through metabolic pathways OTHER than fermentation
What pathway do nonfermenters use?
Entner-Doudoroff (the aerobic pathway) because oxygen is required for glycolysis to occur
Where are nonfermenters commonly found?
in soil, water, and on vegetation; some are primary pathogens to man and animals but are mostly opportunistic pathogens
What is unique about nonfermenters?
they have a high intrinsic resistance to antibiotics and antiseptics as they are derived from the environment
What environmental reservoirs are nonfermenters found in?
flowers, vegetables, soil, lakes and streams, hot tubs, whirlpools, swimming pools, and float tanks
What patient reservoirs are nonfermenters in?
arm pits, between toes, groin, and hands
What reservoirs do we see for nonfermenters in the hospital?
flowers (why you can’t bring flowers in), anesthesia equipment, endoscopes, humidifiers, mist tests, nebulizers, hand creams, water baths, mops, sponges, and hands of personnel
What are predisposing factors to nonfermenter invasion?
malignancies, leukemias, instrumentation (surgery), catheterization (indwelling), placement of shunts and prosthesis, dialysis, steroid treatment, antibiotic therapy, cancer therapy, immunosuppressive meds, chronic disease, open wounds and lesions, BURNS
What is the most common nonfermenter we see?
pseudomonas aeruginosa (65-85%)
What clues do we get?
has an odor of pound water, aquarium, or spoiled fruit
What are the characteristics of Pseudomonas aeruginosa?
1) slender, gram-negative rods
2) oxidase positive
3) usually beta-hemolytic with a ‘green-metallic sheen’
4) fruity odor
5) oxidize glucose
6) grow on MacConkey Agar
7) motile by polar flagella
What infections does Pseudomonas aeruginosa cause?
septicemia in neutropenic patients, necrotizing wound infections in burn patients, chronic lung infections caused by mucoid strains in CF patients, dermatitis in hot tub and flotation tank users, ear infections, gastrointestinal infections
How do we identify P. aeruginosa?
from the blue or fluorescent pigment is produces and grows at 42 C
What are the characteristics of Acinetobacter baumannii?
1) cocci or coccobacillary on gram-stain (negative but OFTEN retains crystal violet)
2) nonmotile
3) grows on MacConkey where strong colonization can make colonies appear purple
4) oxidase negative
5) notoriously resistant to soaps and therefore most common GNR on skin of hospital personnel
What infections can Acinetobacter baumannii cause?
can affect every organ system, urinary and respiratory tracts, soft tissues, bacteremia and meningitis being more common
What are the characteristics of Stenotrophomonas maltophilia?
1) short to medium length GNR
2) slowly oxidise glucose, rapidly breakdown maltose
3) oxidase negative
4) grow on MacConkey agar
5) colonies on sheep agar appear greenish but negative oxidase distinguishes from pseudomonas
6) motile
7) increased innate resistance to many broad-spectrum antibiotics (imipenem)
What infections does S. maltophilia cause?
colonizes oropharynx of adults; infects wounds, lung, CSF, urinary tract and blood; occurs in immunocompromised and those on ventilators
What are the characteristics of Burkholderia cepacia?
1) oxidized glucose
2) oxidase positive, weakly positive, or negative
3) grows on MacConkey and Sheep but may be delayed because it prefers low temps
4) straight to slightly curved GNR
5) motile
6) odor like potato cellar or freshly opened potato sack
What infections does Burkholderia cepacia cause?
soft rot of onions; usually stick to infecting cystic fibrosis patients (opportunistic pathogen) that causes high morbidity
