1. Gram-negative Rods: Glucose nonfermenting
Karen Honeycutt, M.Ed., MT(ASCP)SM
MT 418 Clinical Microbiology
Student Laboratory Session
Microbiology

2. General Information Predominantly opportunistic Debilitated host
GNR: Glucose nonfermenters
General Information
Predominantly opportunistic
Debilitated host
Nomenclature changes rapidly (usually known by 2 names for 5-10 years)
Will grow on BAP, 22-35°C, hours
Categories based upon: glucose, oxidase & ability to grow on MAC
Microbiology

3. GNR: Glucose nonfermenters
General Information
Gram stain morphology taken from non-inhibitory agar
Can be difficult to treat, can rapidly develop antibiotic resistance to drugs used for treatment
Many genera
Commercial system reliability?
Microbiology

4. Glucose “O”, oxidase +, MAC +
GNR: Glucose nonfermenters
Glucose “O”, oxidase +, MAC +
Pseudomonas sp.
Pseudomonas aeruginosa most commonly isolated nonfermenting GNR
Grows in moist environments (soap)
Aerobic
Motile w/polar flagella
Microbiology

5. Pseudomonas aeruginosa
GNR: Glucose “O”, Oxidase +, MAC +
Pseudomonas aeruginosa
Nosocomial infections
Usually not part of normal flora
Colonization can occur (upper respiratory tract, skin, GI tract)
Microbiology

6. P. aeruginosa - Pigments
GNR: Glucose “O”, Oxidase +, MAC +
P. aeruginosa - Pigments
Usually produces
Pyoverdin (fluorescein) – yellow/green; visualize with UV light; Other Pseudomonas sp. can also produce
Pyocyanin – blue-green pigment; only produced by P. aeruginosa
May produce
Pyorubrin – pink to red/maroon pigment; only produced by P. aeruginosa
Microbiology

7. Pseudomonas aeruginosa Id
GNR: Glucose “O”, Oxidase +, MAC +
Pseudomonas aeruginosa Id
BAP
Oxidase
Glucose OF = “O”
MAC
Microbiology

8. Pseudomonas aeruginosa Id
GNR: Glucose “O”, Oxidase +, MAC +
Pseudomonas aeruginosa Id
Moeller base decarboxylase/dehydrogenase Arginine + Ornithine (-) Lysine (-)
Glucose “O” Green pigment
Microbiology

9. Pseudomonas aeruginosa Rapid Id
GNR: Glucose “O”, Oxidase +, MAC +
Pseudomonas aeruginosa Rapid Id
Oxidase
BAP
Rough & beta-hemolytic on BAP Pigment Grape-like smell
Microbiology

10. Pseudomonas aeruginosa infections
GNR: Glucose “O”, Oxidase +, MAC +
Pseudomonas aeruginosa infections
Cystic fibrosis patients – serious lung infections
Immunosuppressed
Burn wounds
Osteomyelitis
UTI, septicemia,
Corneal ulcers (blindness)
Swimmer’s ear, folliculitis
Microbiology

11. Pseudomonas aeruginosa infections
GNR: Glucose “O”, Oxidase +, MAC +
Pseudomonas aeruginosa infections
Corneal ulcers (blindness)
Photo from Images.MD
Microbiology

12. Pseudomonas aeruginosa infections
GNR: Glucose “O”, Oxidase +, MAC +
Pseudomonas aeruginosa infections
Burn wound
Photo from Images.MD
Microbiology

13. Burkholderia cepacia Nosocomial infections
GNR: Glucose “O”, Oxidase +/-, MAC +
Burkholderia cepacia
Nosocomial infections
CF patient – colonized/infected with: severe social ramifications; person to person spread established
Some CF – once infected with: fulminant decline of pulmonary function
Resistant to many antibiotics
Microbiology

14. Glucose “O” or “I”, oxidase (-), MAC +
GNR: Glucose nonfermenters
Glucose “O” or “I”, oxidase (-), MAC +
Stenotrophomonas maltophilia
Strong maltose oxidizer
Nosocomial
Opportunistic
3rd most common glucose non-fermenter isolated in clinical lab
Microbiology

15. Stenotrophomonas maltophilia
GNR: Glucose “O” or “I”, oxidase (-), MAC +
Stenotrophomonas maltophilia
BAP: may produce a pale yellow to lavender pigment
Oxidase negative
Arginine (-), Ornithine (-), Lysine (+)
DNase (+)
Polymyxin B = “S”
Disk diffusion susceptibilities now standardized (SXT “S” – drug of choice)
Microbiology

16. Glucose “O” or “I”, oxidase (-), MAC +
GNR: Glucose “O” or “I”, oxidase (-), MAC +
Glucose “O” or “I”, oxidase (-), MAC +
Acinetobacter sp.
2nd most common glucose non-fermenter isolated in clinical lab
Nosocomial
Opportunistic
Normal flora: skin, vaginal tract
Microbiology

17. GNR: Glucose “O” or “I”, oxidase (-), MAC +
Acinetobacter sp.
Gram stain morphology: plump gnr in pairs (can be mistaken for GNDC)
Oxidase (-)
Nitrate reduction (-)
Glucose
“O” Acinetobacter baumannii
“I” Acinetobacter lwoffii
Microbiology