Nonfermenters Flashcards
What does EMP stand for ?
Embden-Meyerhof-Parnas pathway
What does ED stand for ?
Entner-Douderoff pathway
What are characteristics of the EMP pathway ?
Embden-Meyerhof-Parnas pathway
- anaerobic pathway
- no O2 involved
- used by anaerobes & facultative anaerobes, and fermenters
- used for fermenting organisms
What is the final acceptor in the EMP pathway ?
organic compound
- pyruvic acid converted to lactic acid or mixed acids
- produces strong acid products and usually has (detected by a drop in pH of test)
What are some characteristics of the ED pathway ?
Entner-Douderoff pathway
- O2 required
- used by aerobic and facultative anaerobes
- not using fermentation, aerobic organisms therefore called nonfermenters
- makes weak acids in the process
- no gas production (end product = h20 no gas)
What is the final acceptor in the ED pathway ?
oxygen
- end products is water with no gas
What are some clues to nonfermenters ?
- KIA shoes red/red reaction (all glucose nonfermenters are also lactose nonfermenters)
- typically Oxidase + (has enzyme cytochrome oxidase) but some are (-)
- some grow poorly on MAC agar (if they do grow then the colony will be colorless which indicates non-lactose fermenting colonies)
What is the virulence of the nonfermenters ?
has low grade virulence (typically don’t cause problems)
- opportunistic though
- can rapidly develop resistance to antimicrobials
- commonly cause nosocomial infections in patients who are debilitated or immunocompromised
What are the clinically significant nonfermentive Gram (-) bacilli ?
acinetobacter & pseudomonas
What are some conditions/diseases that create factors for infection ?
- malignancies
- instrumentation and surgery (catheterization, lumbar puncture, dialysis, shunts, artificial body parts)
- prolonged steroid use, antibiotics, and anticancer therapy
- underlying metabolic or chronic diseases
- burns, opens wounds, and various exudative lesions
What is the natural habitat of nonfermenters ?
- humidifiers, ventilators, water baths, disinfectant, distraction water supplies, hand-creams, etc
- frequently in fluids used in the hospitals (IV fluids, irrigation solutions)
- devices like anesthesia equipment, forceps, and thermometers
- moist parts of the skin
- various domestic animals predisposing caretakers to infections
What is the isolation pattern of nonfermenters ?
- pseudomonas aeruginosa: 75%
- Acinetobacter species: 20%
- other pseudomonas: 3.5%
- other nonfermenters: 1%
What are some general characteristics of Pseudomonas Aeruginosa ?
- Oxidase +
- grows well on MAC agar
- motile (able to move on media and out)
- produces pigment pyocyanin (blue-green color, metallic sheen)
Where would you find pseudomonas aeruginosa infections ?
commonly at moist sites
- indwelling catheters
- burns
- external ear (swimmers ear)
- weeping cutaneous wounds
- eye infections (can cause permanent loss of vision within 24 hrs)
- endocarditis, meningitis, brain abscess and infection of bones and joints
How would you identify pseudomonas aeruginosa ?
- MAC plate: form colorless colonies that are larger in size
- blue-green pigment (pyocyanin) with metallic appearance
- pungent sweet-like odor
- KIA: K/K (red/red) nonfermenter (don’t ferment lactose -)
- oxidase +
- grows on 25, 37, and 42 C
What is the susceptibility of pseudomonas aeruginosa to antibiotics ?
resistant to many common antibiotics
What are some general characteristics of Acinetobacter ?
- gram (-) coccobacillary
- small translucent colonies on BAP (ammonia like odor)
- non motile
- grows well on MAC agar
- oxidase (-) (lacks enzyme cytochrome oxidase)
How do you identify Acinetobacter ?
- extremely short rods
- translucent, never pigmented, may have slight pink color on MAC even though its a non-lactose fermenter
What is the natural habitat of the Acinetobacter ?
- widely dispersed in soil, water, and sewage
- found colonizing the regions of human skin
- may be normal flora of oropharynx and vagina
What types of infections are caused by Acinetobacter ?
- pneumonia often related to endotracheal tubes, IV catheters, shunts
- endocarditis, meningitis, skin and wound
- peritonitis in pt’s receiving peritoneal dialysis
- urinary tract infections (indwelling catheters)
What is the susceptibility of Acinetobacter to antibiotics ?
tend to be resistant to antibiotics
- antibiotic testing must guide choice of effective antibiotic treatment
