microbiology gram-negative rods: glucose nonfermenting karen honeycutt, m.ed., mt(ascp)sm mt 418...
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Microbiology
Gram-negative Rods:Glucose nonfermenting
Karen Honeycutt, M.Ed., MT(ASCP)SM
MT 418 Clinical Microbiology
Student Laboratory Session
Microbiology
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
GNR: Glucose nonfermenters
Microbiology
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?
GNR: Glucose nonfermenters
Microbiology
Glucose “O”, oxidase +, MAC +• Pseudomonas sp.
– Pseudomonas aeruginosa most commonly isolated nonfermenting GNR
• Grows in moist environments (soap)
• Aerobic • Motile w/polar flagella
GNR: Glucose nonfermenters
Microbiology
Pseudomonas aeruginosa• Nosocomial infections• Usually not part of normal flora• Colonization can occur (upper respiratory
tract, skin, GI tract)
GNR: Glucose “O”, Oxidase +, MAC +
Microbiology
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
GNR: Glucose “O”, Oxidase +, MAC +
Microbiology
Pseudomonas aeruginosa Id
Glucose OF = “O”
OxidaseBAP
MAC
GNR: Glucose “O”, Oxidase +, MAC +
Microbiology
Pseudomonas aeruginosa Id
Moeller base decarboxylase/dehydrogenaseArginine +Ornithine (-)Lysine (-)
Glucose “O”Green pigment
GNR: Glucose “O”, Oxidase +, MAC +
Microbiology
Pseudomonas aeruginosa Rapid Id
OxidaseBAP
Rough & beta-hemolytic on BAPPigmentGrape-like smell
GNR: Glucose “O”, Oxidase +, MAC +
Microbiology
Pseudomonas aeruginosa infections• Cystic fibrosis patients – serious lung
infections• Immunosuppressed • Burn wounds• Osteomyelitis• UTI, septicemia, • Corneal ulcers (blindness)• Swimmer’s ear, folliculitis
GNR: Glucose “O”, Oxidase +, MAC +
Microbiology
Pseudomonas aeruginosa infections
• Corneal ulcers (blindness)
GNR: Glucose “O”, Oxidase +, MAC +
Photo from Images.MD
Microbiology
Pseudomonas aeruginosa infections
• Burn wound
GNR: Glucose “O”, Oxidase +, MAC +
Photo from Images.MD
Microbiology
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
GNR: Glucose “O”, Oxidase +/-, MAC +
Microbiology
Glucose “O” or “I”, oxidase (-), MAC +
• Stenotrophomonas maltophilia – Strong maltose oxidizer
• Nosocomial
• Opportunistic
• 3rd most common glucose non-fermenter isolated in clinical lab
GNR: Glucose nonfermenters
Microbiology
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)
GNR: Glucose “O” or “I”, oxidase (-), MAC +
Microbiology
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
GNR: Glucose “O” or “I”, oxidase (-), MAC +