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Nonfermenting GN Rods

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Title: Chapter 16 - Enterobacteriaceae Author: Instructional Technology Last modified by: kbrophym Created Date: 7/14/2005 5:59:43 PM Document presentation format – PowerPoint PPT presentation

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Title: Nonfermenting GN Rods


1
Nonfermenting GN Rods Miscellaneous GN Rods
  • MLAB 2434 Microbiology
  • Keri Brophy-Martinez

2
General Characteristics of Nonfermenters
  • Nonfermentative organisms that break down
    carbohydrates oxidatively (aerobically) are also
    called oxidizers or saccharolytic
  • Organisms that are NOT able to break down
    carbohydrates fermentatively or oxidatively are
    called biochemically inert, nonoxidizersor
    nonsaccharolytic

3
General Characteristics of Nonfermenters (contd)
  • Nonfermenters are ubiquitous in the environment
  • Predominantly opportunistic
  • Also isolated in hospitals from nebulizers,
    dialysate fluids, saline, and catheter devices
  • Somewhat resistant to disinfectants antibiotics

4
The Nonfermenters
  • Achromobacter
  • Acidovorax
  • Acinetobacter
  • Agrobacterium
  • Alcaligenes
  • Burkholderia
  • Stenotrophomonas
  • Chryseobacterium
  • Chryseomonas
  • Comamonas
  • Flavimonas
  • Flavobacterium
  • Methylobacterium
  • Moraxella
  • Weeksekka
  • Ochrobactrum
  • Oligella
  • Pseudomonas
  • Psychrobacter
  • Roseomonas
  • Shewanella
  • Sphingobacterium

5
Clinical Infections
  • Septicemia
  • Meningitis
  • Osteomyelitis
  • Wound infections following surgery or trauma
  • Nosocomial Infections

6
Clinical Infections
  • Risk factors
  • Immunosuppression
  • Foreign body implantation
  • Traumatic break in a host barrier
  • Antibiotic therapy
  • Underlying disease

7
Initial Clues to Nonfermenters
  • Long, thin gn rods or cb
  • Oxidase positive (not ALL nonfermenters)
  • No or slow growth of MacConkey agar
  • Nonreactive in 24 hours on commercial kit systems
  • TSI nonreactive
  • Resistant to antibiotics ( penicillin, ampicillin
    cephalosporins)
  • Treat with aminoglycosides, quinolones and
    anti-pseudomonal penicillins ( ticarcillin,
    piperacillin)

8
Nonfermenter Organization
  • Nonfermenters are grouped according to three
    characteristics
  • Growth on MacConkey
  • Not all nonfermenters grow on MAC
  • All nonfermenters that grow on MAC are lactose
    negative
  • Oxidase reaction
  • OF test

9
Commonly Encountered Nonfermentative Organisms
  • Pseudomonas characteristics
  • Associated with water and moist environments
  • Not common as normal flora
  • Strict aerobe
  • GN rods or cb
  • Usually motile with polar or polar tufts of
    flagella
  • Oxidase and catalase positive
  • Usually grows on MacConkey agar
  • Usually oxidizes carbohydrates

10
Pseudomonas aeruginosaClinical Infections
  • Types of infections
  • Bacteremia with ecthyma gangrenosum of skin
  • Wound infections
  • Pulmonary disease (esp. in Cystic Fibrosis)
  • Nosocomial UTI
  • Endocarditis
  • Meningitis
  • Otitis externa (swimmers ear)
  • Hot tub syndrome (skin rash)

11
Pseudomonas aeruginosaVirulence Factors
  • Endotoxins
  • Hemolysins
  • Cytotoxins
  • Proteases
  • Slime
  • Pili

12
P. aeruginosa Laboratory identification
  • Beta-hemolytic on blood agar
  • Green metallic sheen due to production of pigment
    pyocyanin (bluish-green)
  • Most strains also produce pigment pyoverdin
    (yellowish-green fluorescence)
  • Odor described as grape-like or Frito-like

13
Honorable mentions
  • Pseudomonas fluorescens Pseudomonas putida
  • Produces pyoverdin but not pyocyanin
  • Rarely causes clinical disease
  • Found in water and soil, usually environmental
    contaminants
  • Pseudomonas stutzeri
  • Wrinkled, leathery colonies that may be light
    yellow or brown, non- fluorescent

14
Stenotrophomonas maltophilia
  • Third most common nonfermenter cultured,
    ubiquitous in nature
  • Common in the hospital environment
  • Implicated in infections of wounds, RT, UT and
    blood
  • Frequent isolate of Cystic Fibrosis patients

15
Other Nonfermenters
  • Acinetobacter found in hospital environments
    can cause opportunistic infection, skin/vaginal
    normal flora. On BAP transluscent-opaque, MAC
    colorless. On gram stain, short plump gncb
  • Burkholderia cepacia most often associated with
    pneumonia in Cystic Fibrosis
  • Burkholderia pseudomallei causes melioidosis(
    an aggressive pulmonary disease causing
    pneumonia, abscesses and septicemia)
  • Alcalingenes found in water and resistant to
    disinfectants

16
References
  • Engelkirk, P. G., Duben-Engelkirk, J. (2008).
    Laboratory Diagnosis of Infectious Diseases
    Essentials of Diagnostic Microbiology .
    Baltimore, MD Lippincott Williams Willkins.
  • Kiser, K. M., Payne, W. C., Taff, T. (2011).
    Clinical Laboratory Microbiology A Practical
    Approach . Upper Saddle River, NJ Pearson
    Education, Inc.
  • Mahon, C. R., Lehman, D. C., Manuselis, G.
    (2011). Textbook of Diagnostic Microbiology (4th
    ed.). Maryland Heights, MO Saunders.
  • http//www.microbelibrary.org/library/laboratory-t
    est/2862-blood-agar-plates-and-hemolysis-non-ferme
    nting-gram-negative-rods-including-pseudomonas-aer
    uginosa
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