Non-fermentative GNR

Define non-fermentative organism

aerobic non-spore forming bacilli that do not ferment glucose

3 primary criteria to ID no-fermentative GNR

• Gram stain morphology

• Cytochrome C oxidase

• Growth on MAC

Non-fermenter

• oxygen required

• weak acid end product

Fermenter

• no oxygen required

• strong acid end product

Oxidative fermentative media (OF): purpose

determine if fermenter or not

Oxidative fermentative media (OF): procedure

• two tubes

• stab

• layer one with mineral oil

• incubate in ambient air

OF media interpretation: oxidizer/saccharolytic

• yellow in open tube

• no change/blue in oiled tube

OF media interpretation: non-oxidizer/asaccharolytic

no change/blue in both tubes

OF media interpretation: fermenter

yellow in both tubes or yellow in only oiled tube

3 most common non-fermenters found in lab (in order)

1. pseudomonas aeruginosa

2. Acinetobacter spp

3. Stenotrophomonas maltophilia

name and color of pigments by some non-fermenters

1. pyocyanin = blue

2. pyoverdin = green

3. pyoruloin = red

4. pyomelanin = brown

5. carotenoids, violacein, phenazine

Pseudomonas aeruginosa: habitat

aqueous solutions

Pseudomonas aeruginosa: SBA and MAC

• SBA = varibale morphology (metallic,flat,rough texture, pigments etc)

• MAC = lactose negative (clear)

Pseudomonas aeruginosa: clinical significance

most common NF in lab

Pseudomonas aeruginosa: pathogenicity

• pili

• capsule

• exotoxins

• endotoxins

• biofilm

Pseudomonas aeruginosa: identification

• Oxidase positive

• Motile

• oxidizer

• growth at 42C

• pigment production (pyocyanin unique)

Pseudomonas fluorescens/ putida: identification

No growth at 42C

Pseudomonas fluorescens/ putida: biochemicals

same as pseudomonas aeruginosa

Pseudomonas fluorescens/ putida: disease

linked to transfusion associated septicemia

Acinetobacter baumannii: characteristics

• 2nd most common NF

• odor of old gym socks

Acinetobacter baumannii: clinical significance

nosocomial infections

Acinetobacter baumannii: SBA and MAC

SBA = grey, medium, size colonies

MAC = Lactose negative with lavender hue

Acinetobacter baumannii: Identification

• GNC/B

• Oxidase negative

• non-motile

• Saccharolytic (baumannii)

• Asaccharolytic (Iwoffii)

Stenotrophomonas maltophilia: Identification

• straight GNR

• Oxidase negative

• motile

Stenotrophomonas maltophilia: SBA and MAC

SBA = small grey colonies

MAC = lactose negative

Stenotrophomonas maltophilia: Clinical significance

• 3rd most common NF in lab

• nosocomial infections

Burkholderia cepacia complex: identification

• straight GNR

• MALDI-TOF

Burkholderia cepacia complex: clinical significance

• cystic fibrosis

• chronic granulomatous disease

Burkholderia cepacia complex: SBA,MAC, and PC

SBA = yellow hue

MAC = lactose negative

PC = if growth could be B. cepacia and yellow hue

purpose of tryptone glucose yeast extract (TGY)

• determines growth at a range of temperatures

• tests 25C, 35C and 42C

Two organisms commonly found in cystic fibrosis patients

1. B. multivorans

2. B. cenocepacia

what is strange about B. cepacia complex and oxidase test

it is delayed (longer then 30 secs)

what about B. cepacia complex and resistance

highly resistant antibiogram

What media is used to isolate B cepacia complex

PC agar

What must be ruled out from listeria spp

• listeria is NOT opaque (white)

• listeria is NOT alpha hemolytic

Which GPRs are catalase negative

• Lactobacillus

• Erysipelothrix rhuslopathiae

• Arcanobacterium haemolyticum