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

Gram-negative Rods:
Glucose nonfermenting
Karen Honeycutt, M.Ed., MT(ASCP)SM
MT 418 Clinical Microbiology
Student Laboratory Session
Microbiology
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, 24-72 hours
• Categories based upon: glucose,
oxidase & ability to grow on MAC
Microbiology
GNR: Glucose nonfermenters
General Information
• Gram stain morphology taken from noninhibitory agar
• Can be difficult to treat, can rapidly
develop antibiotic resistance to drugs
used for treatment
• Many genera
• Commercial system reliability?
Microbiology
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
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
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
GNR: Glucose “O”, Oxidase +, MAC +
Pseudomonas aeruginosa Id
Oxidase
BAP
Glucose OF = “O”
MAC
Microbiology
GNR: Glucose “O”, Oxidase +, MAC +
Pseudomonas aeruginosa Id
Glucose “O”
Green
pigment
Microbiology
Moeller base
decarboxylase/dehydrogenase
Arginine +
Ornithine (-)
Lysine (-)
GNR: Glucose “O”, Oxidase +, MAC +
Pseudomonas aeruginosa Rapid Id
Oxidase
BAP
Rough & beta-hemolytic on BAP
Pigment
Grape-like smell
Microbiology
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
GNR: Glucose “O”, Oxidase +, MAC +
Pseudomonas aeruginosa infections
• Corneal ulcers
(blindness)
Photo from Images.MD
Microbiology
GNR: Glucose “O”, Oxidase +, MAC +
Pseudomonas aeruginosa infections
• Burn wound
Photo from Images.MD
Microbiology
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
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
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
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
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