WEEK 13: NONFERMENTING GRAM NEGATIVE BACILLI

Question 1

a. Grow in MacConkey as colorless colonies
b. Fail to acidify O-F Media, overlaid with mineral oil
c. Fail to acidify TSI Agar
d. Most isolates is Oxidase Positive
e. Resistance to a variety of classes of
antimicrobial agents (beta lactamase and aminoglycosides)

Answer 1

NONFERMENTING GRAM NEG. BACILLI

Question 2

No change in color in both tube in O-F Media. Nonsaccharolytic organisms.

Answer 2

Alcaligenes, Oligella

Question 3

Change in color in tubes
w/out mineral oil (Open tube)

Answer 3

Oxidative

Question 4

Organisms that are negative in Oxidase Test (colorless)

Answer 4

Acinetobacter and Stenotrophomonas

Question 5

Organisms that are positive in Oxidase Test (dark purple)

Answer 5

Pseudomonas and Burkholderia

Question 6

1. Most commonly isolated species
   ▪ 75% of nonfermenters in nosocomial bacteremias and 5% to 15% of nosocomial infections
2. Causes bacteremia, wound infection, pulmonary disease (Cystic fibrosis patients), UTI, endocarditis, meningitis
3. Otitis media and Jacuzzi/hot tub syndrome

Answer 6

Pseudomonas aeruginosa

Question 7

Pseudomonas aeruginosa can cause bacteremia leading to?

Answer 7

ecthyma gangrenosum

Question 8

most important exotoxin in Pseudomonas aeruginosa; blocks protein synthesis

Answer 8

Exotoxin A

Question 9

Polysaccharide polymer in mucoid strains

Answer 9

Alginate

Question 10

1. Strict aerobic
2. Pigmented
3. Fruity, Grapelike or
   “corn tortilla-like” Odor
   (2-aminoacetophenone)
4. Growth at 42°C
5. Grows in Cetrimide Agar
6. Acetamide Positive

Answer 10

Pseudomonas aeruginosa

Question 11

Fluorescein (Pyoverdin)

Answer 11

P.fluorescens/P. putida

Question 12

Pyomelanin

Answer 12

P. stutzeri

Question 13

• Bluish-green, red, or brown pigmentation, β-hemolytic in BAP
• Bluish-green, red, or brown diffusible pigment in Mueller Hinton

Answer 13

Pseudomonas aeruginosa

Question 14

Organism that is often mistaken as Neisseria

Answer 14

Acinetobacter spp.

Question 15

1. Associated with ventilators, humidifiers, catheters, etc.
2. Opportunistic (1-3% of all nosocomial infection, 2nd most commonly isolated non-fermenter); burns, trauma
3. About 25% of adults present in skin; 7% in pharynx
4. Ubiquitous; found in soil, water, foodstuffs

Answer 15

Acinetobacter spp.

Question 16

• Saccharolytic (glucose oxidizing), nonhemolytic strains.
• may exhibit purplish hue (due to lactose
  oxidation)
• appears with a blue-grey (cornflower blue) center in EMB.

Answer 16

A. baumannii

Question 17

Asaccharolytic, nonhemolytic strains.

Answer 17

A. lwoffii

Question 18

β-hemolytic strains.

Answer 18

A. haemolyticus

Question 19

Plump, paired gram negative coccobacilli

Answer 19

Acinetobacter spp.

Question 20

1. Contaminants in blood drawing equipment (collection tubes, disinfectants, transducers, venous catheters, etc.)
2. Opportunistic (3rd most commonly isolated among nonfermenters)
3. Intrinsic resistance commonly used antibacterial agent (aminoglycosides and beta lactams)

Answer 20

Stenotrophomonas maltophilia

Question 21

1. Oxidase negative
2. Catalase, Dnase positive
3. Esculin and Gelatin hydrolysis (+)
4. Lysine decarboxylase positive

Answer 21

Stenotrophomonas maltophilia

Question 22

1. Pneumonia in patients with cystic fibrosis or chronic granulomatous disease
2. Isolated from irrigation fluids, anesthetics, nebulizers, detergents and disinfectants.
3. Onion bulb rot in plants and foot rot in humans
4. Intrinsic resistance to antibiotics

Answer 22

Burkholderia cepacia

Question 22

Organism that is positive in Acetamide Utilization

Answer 22

Pseudomonas aeroginusa

Question 22

▪ “Melioidosis” (pulmonar disease) formation of abscess

1. Bipolar staining (safety pin) in Gram Stain
2. Smooth to wrinkled colonies in BAP
3. Wrinkled and deep pink in Ashdown media
4. “Earthy odor”
5. “Sniffing” of plate is discouraged (work on BSC)

▪ Culture- Ashdown media

Answer 22

Burkholderia pseudomallei

Question 22

1. Smooth, non-wrinkled and slightly raised; dirtlike odor in BAP 2. NLF; become dark pink to red after 4-7 days in Mac 3. Most strains are ONPG positive 4. Specific selective media (PC, OFPBL, BCSA) 5. Produces a nonfluorescing yellow/green pigment

Answer 22

Burkholderia cepacia

Question 23

1. lavender green pigment in BAP 2. Ammonia-like smell 3. Oxidizes glucose: W(+/-) 4. Oxidizes maltose: S(+)

Answer 23

Stenotrophomonas maltophilia

Question 24

“Associated with patients with CF (cystic fibrosis) and CGD (chronic granulomatous disease)

Answer 24

Burkholderia gladioli

Question 25

Selective and differential media used for Pseudomonas aeroginusa that enhances pigment (pyoverdid and pyocyanin)

Answer 25

Cetrimide Agar

Question 25

▪ Glanders- zoonosis affecting horses, mules, donkeys. Formation of nodular lesions in lungs. Coughing, fever and release of infectious nasal discharge. ▪ Potential bioterrorist agent ▪ Nonmotile; non-pigmented colonies; no distinct odor

Answer 25

Burkholderia mallei

Question 25

Good growth at both 35°C and 42°C

Answer 25

Pseudomonas aeroginusa Stenotrophomonas maltophilia

Question 26

No growth at 42°C but good growth at 35°C

Answer 26

Pseudomonas fluorescens Pseudomonas putida