Non-Fermentative Gram-Negative Bacilli & Related Microbiology Concepts

0.0(0)
studied byStudied by 8 people
learnLearn
examPractice Test
spaced repetitionSpaced Repetition
heart puzzleMatch
flashcardsFlashcards
Card Sorting

1/42

flashcard set

Earn XP

Description and Tags

Vocabulary flashcards covering key terms, organisms, pigments, media, and biochemical tests related to non-fermentative Gram-negative bacilli.

Study Analytics
Name
Mastery
Learn
Test
Matching
Spaced

No study sessions yet.

43 Terms

1
New cards

Opportunistic pathogen

A microorganism that normally does not cause disease but can produce infections in immunocompromised or hospitalized patients.

2
New cards

Non-fermentative Gram-negative bacilli (NFGNB)

Environmental Gram-negative rods that oxidize but do not ferment carbohydrates; common opportunists in hospitals.

3
New cards

Oxidative-Fermentative (OF) test

Biochemical assay that differentiates oxidizers from fermenters by detecting acid production in open (aerobic) and oil-sealed (anaerobic) tubes.

4
New cards

Hugh and Leifson OF medium

Semisolid medium containing carbohydrates (e.g., glucose) and bromthymol blue pH indicator for the OF test.

5
New cards

Bromthymol blue

pH indicator in OF medium that turns yellow in acid and blue in alkaline conditions.

6
New cards

Oxidizer

Bacterium that produces acid only in the open tube of the OF test, indicating aerobic carbohydrate metabolism.

7
New cards

Fermenter

Bacterium that produces acid in both open and closed OF tubes, indicating anaerobic and aerobic carbohydrate utilization.

8
New cards

Triple Sugar Iron Agar (TSIA)

Differential slant medium with glucose, lactose, sucrose (1:10:10) plus phenol red to detect sugar fermentation, H₂S and gas.

9
New cards

Slant / Butt (TSIA)

Upper aerobic portion (slant) and lower anaerobic portion (butt) of TSIA used to interpret metabolic reactions.

10
New cards

Phenol red

pH indicator in TSIA that turns yellow in acid and remains/reddened in alkaline conditions.

11
New cards

A/A (Acid/Acid)

TSIA result showing yellow slant and butt, indicating fermentation of glucose plus lactose and/or sucrose.

12
New cards

K/A (Alkaline/Acid)

TSIA result with red slant, yellow butt; glucose fermented but lactose/sucrose not fermented.

13
New cards

K/K (Alkaline/Alkaline)

TSIA reaction with red slant and butt, indicating no sugar fermentation (typical of non-fermenters).

14
New cards

H₂S production

Black precipitate in TSIA butt caused by hydrogen sulfide reacting with iron salts.

15
New cards

Gas production (TSIA)

Bubbles, cracks, or media lift indicating CO₂ / H₂ gas formation during carbohydrate fermentation.

16
New cards

Oxidase test

Rapid assay detecting cytochrome c oxidase with tetramethyl-p-phenylenediamine; positive colonies turn purple within 10 s.

17
New cards

Cytochrome c oxidase

Terminal electron-transport enzyme detected by the oxidase test; present in many oxidizers like Pseudomonas.

18
New cards

Pseudomonas aeruginosa

Most common NFGNB; produces pyocyanin, grape-like odor, β-hemolytic colonies, and causes ‘blue pus’ infections.

19
New cards

Pyocyanin

Blue, water-soluble pigment unique to P. aeruginosa responsible for its green/blue colony coloration.

20
New cards

Pyoverdine

Yellow-green siderophore pigment of many Pseudomonas spp.; combines with pyocyanin to give green sheen.

21
New cards

Blue pus

Purulent exudate colored blue by pyocyanin from P. aeruginosa infection.

22
New cards

Swimmer’s ear (Acute otitis externa)

Painful external ear infection frequently caused by Pseudomonas aeruginosa in contaminated water.

23
New cards

Exotoxin A

Major P. aeruginosa virulence factor that inhibits protein synthesis by ADP-ribosylating EF-2.

24
New cards

Grape / tortilla odor

Characteristic sweet smell of P. aeruginosa colonies due to 2-aminoacetophenone.

25
New cards

Cetrimide agar

Selective medium that enhances pigment production and growth of Pseudomonas aeruginosa.

26
New cards

Acinetobacter baumannii

Second most common NFGNB; oxidase-negative, non-motile, produces purple colonies on MacConkey; notable nosocomial pathogen.

27
New cards

Stenotrophomonas maltophilia

Oxidase-negative NFGNB producing lavender-green colonies with ammoniacal odor; maltose-loving and frequent blood culture contaminant.

28
New cards

Burkholderia cepacia complex

Group of motile oxidase-weak NFGNB that form yellow colonies; important in cystic fibrosis pneumonia and IV-drug endocarditis.

29
New cards

Burkholderia mallei

Non-motile species causing Glanders (Farsi) primarily in equines; potential bioterrorism agent.

30
New cards

Glanders (Farsi disease)

Zoonotic infection by Burkholderia mallei characterized by ulcerating nodules and septicemia.

31
New cards

Burkholderia pseudomallei

Agent of Melioidosis (‘Vietnamese time-bomb’); produces dry wrinkled colonies with earthy odor; found in muddy soil.

32
New cards

Melioidosis

Severe infection mimicking many illnesses, acquired from Burkholderia pseudomallei in soil or water aerosols.

33
New cards

Tetramethyl-p-phenylenediamine dihydrochloride

Reagent used in oxidase test; reduced form turns purple when oxidized by cytochrome c oxidase.

34
New cards

Monotrichous flagellation

Single polar flagellum pattern seen in Pseudomonas aeruginosa providing motility.

35
New cards

Nosocomial infection

Infection acquired in a hospital setting, often caused by opportunistic NFGNB.

36
New cards

Lavender-green pigment

Distinct colony color of Stenotrophomonas maltophilia on blood agar.

37
New cards

Ammoniacal odor

Sharp smell produced by colonies of Stenotrophomonas maltophilia.

38
New cards

Maltose utilization

Metabolic trait of S. maltophilia producing acid from maltose but not glucose.

39
New cards

Wrinkled colony morphology

Dry, folded surface appearance typical of Burkholderia pseudomallei on culture media.

40
New cards

Strict aerobe

Organism that requires oxygen for growth; includes many non-fermenters like Pseudomonas and Stenotrophomonas.

41
New cards

Moraxella catarrhalis

Oxidase-positive, β-lactamase-producing coccobacillus causing respiratory and ear infections; member of family Moraxellaceae.

42
New cards

Mineral oil overlay (OF test)

Layer providing anaerobic environment in one OF tube to differentiate oxidative vs fermentative metabolism.

43
New cards

1:10:10 sugar ratio (TSIA)

Proportion of glucose:lactose:sucrose in TSIA allowing early depletion of glucose to reveal lactose/sucrose fermentation.