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BACTERIOLOGY > Non-fermentative Gram(-) bacilli > Flashcards

Non-fermentative Gram(-) bacilli Flashcards

1
Q

General characteristic of Non-fermenters:

A

Fail to:
- acidify an oxidative-fermentative (OF)
medium when it is overlaid with mineral oil

  • acidify triple sugar iron agar (TSIA) butt
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2
Q

Nonoxidizers or?

A

Asaccharolytic

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3
Q

General characteristic of Non-fermenters:

A
  • prefer and grow in aerobic environment
  • some oxidize carbohydrates as source of energy
  • prefer moist environment (e.g: from nebulizers)
  • can easily colonize hospitalized px
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4
Q

A feature of Non-fermenters that greatly differentiates them from Enterobacteriaceae

A

Oxidase +

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5
Q

Series of infections usually associated with Non-fermenters gram (-) bacilli

A

Septicemia
Meningitis
Osteomyelitis
Wound infections following surgery or trauma

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6
Q

Biochemical Characteristic & Identification:

Fermenters

A

• (+): acid (yellow) butt
• (+): acid or alkaline (red) slant on TSIA or KIA
within 18 h incubation

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7
Q

Biochemical Characteristic & Identification:

Non-fermenters

A
  • fail to ferment carbohydrates
  • No acid production in the slant or butt of TSIA or KIA
  • no change in the butt & slant may produce an alkaline (red) slant
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8
Q

Biochemical Characteristic & Identification:

“true” fermenters

A 
fastidious (e.g., Pasturella multocida)
• do not easily acidify the butt or slant of a
TSIA like other fermenters
• but do show reactions if more enriched
media are used
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9
Q

3 common test for Non-fermenters

A
  • growth on MAC agar
  • oxidase reaction
  • glucose O-F test
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10
Q

4 groups of non-fermenters make up most isolates

routinely seen in clinical laboratories:

A

Pseudomonas aeruginosa
Acinetobacter spp.
Burkholderia spp.
Stenotrophomonas maltophilia

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11
Q

ID of non-fermenters:
based on the site from which they
have been isolated

if they have been recovered from a normally sterile site in pure culture

A
  • requires definitive ID &

susceptibility testing

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12
Q

ID of non-fermenters:
based on the site from which they
have been isolated

if acquired from a nonsterile site in which
3 or 4 other bacterial species are also
present

A
  • genus identification might be
    appropriate thru biochemical test.

e.g: MAC agar, indole, motility, and glucose utilization

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13
Q

MALDI-TOF mass spectrometry

A

a method for the identification of
bacteria & fungi from colonies based on
analysis of the unique spectra of their peptides when separated in a mass spectrophotometer

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14
Q

This genus has the largest percentage of all non-fermenters isolated from clinical specimens

A

Pseudomonas

-specifically pseudomonas aeruginosa

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15
Q

Characteristic common to most Pseudomonads

A
  • gram (-) bacillus/ coccobacillus
  • strictly aerobic
  • motile w/ polar flagellum or polar tuft of flagella
  • oxidase (+)
  • catalase (+)
  • usually grows on MAC agar
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16
Q

Pseudomonas Fluorescent Group:

Pseudomonas aeruginosa

A
  • is the leading cause of nosocomial
    respiratory tract infections
  • accounts for up to 6% of all bacteremias &
    as many as 75% of nosocomial bacteremias
  • is the 3rd most common cause of gram (-)
    bacillary bacteremia (after E.coli and K. pneumoniae)
  • a common cause of lung infections in people with CF
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17
Q

P. aeruginosa is commonly isolated from

A

Sterile body site: blood, pleural fluid, joint fluid, tissues, CSF (constituting a true infection)

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18
Q

less serious conditions associated with P.aeruginosa

A

Otitis externa and infections of nail beds

or in swimmers or divers called as Jacuzzi or hot tub syndrome

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19
Q

A condition caused by P. aeruginosa characterized by necrotizing rash in drivers or swimmers

A

Jacuzzi or hot tub syndrome

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20
Q

Most important exotoxin produced by P. aeruginosa

A

Exotoxin A - cytotoxic; blocks protein synthesis

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21
Q

Identifying characteristics of

P. aeruginosa

A

production of:

  • pyoverdin (yellow-green/ brown)
  • pyocyanin (blue)
  • pyorubin (red)
  • pyomelanin (brown or black)
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22
Q

It is a yellow-green or yellow-brown water soluble pigment produce by P. aeruginosa

A

Pyoverdin

  • fluoresces under short-wavelength UV light
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23
Q

A blue water-soluble pigment that when combined w/ pyoverdin produces green color colonies in MHA (mueller hinton agar)

A

Pyocyanin

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24
Q

What is the color of P.aeruginosa colonies in MHA agar

A

green-colored colonies

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25
Q

What causes the green coloration of colonies of P. aeruginosa in MHA agar

A
  • production of pyoverdin and pyocyanin
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26
Q

P.aeruginosa is resistant to these antibiotics

A
  • Penicillin
  • Ampicillin
  • first- & second-generation cephalosporins
  • trimethoprim-sulfamethoxazole
  • Chloramphenicol
  • tetracyclines
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27
Q

P.aeruginosa is susceptible to these antibiotics

A
  • Aminoglycosides
  • Semisynthetic penicillins: piperacillin and
    ticarcillin
    -third- and fourth generation cephalosporins
    (ceftazidime and cefepime, respectively)
  • carbapenems (except ertapenem)
  • fluoroquinolones
28
Q

Treatment necessary for severe P.aeruginosa

A

Combination therapy

  • Synthetic pencillins or carbapenems w/ aminoglycosides
29
Q

Test used to differentiate P. fluorescens and P. putida

A

Gelatin hydrolysis

  • P. putida (-)
  • P. fluorescens (+)
30
Q

Pseudomonas Fluorescent Group:

P. fluorescens

A

-isolated from blood culture bottles
- pyocyanin (-)
- pyoverdin (+)
- responsible for clusters
of pseudobacteremia, probably related to
contaminated catheters & catheter-related
devices

31
Q

Pseudomonas Fluorescent Group:

P. putida

A
  • catheter-related sepsis
    in patients with cancer
  • pyocyanin (-)
  • pyoverdin (+)
32
Q

Pseudomonas Fluorescent Group:

both P.fluorescens & P. putida

A
  • grows as 4 celcius
  • cannot grow at 42 celcius
  • linked to transfusion-associated septicemia
  • cannot reduce nitrate to nitrite
  • can produce acid from xylose
33
Q

Pseudomonas Nonfluorescent Group:

P. stutzeri

A
  • recognizable macroscopic appearance of wrinkled, leathery, adherent colonies that produces light-yellow or brown pigment.
34
Q

Biochemical test that specifically distinguish P.stutzeri from other Pseudomonanas spp.

A

Combination of:

  • Starch hydrolysis (+) and ADH (-)
35
Q

Pseudomonas Nonfluorescent Group:

P. mendocina

A
  • produces non-wrinkled, flat colonies
  • yellowish-brown pigment
  • motile (single polar flagellum)
  • pigmentation (variable): smooth buttery appearance
36
Q

Pseudomonas pseudoalcaligenes &

Pseudomonas alcaligenes

A
  • oxidase (+)
  • biochemically (-)
  • capable of reduction of nitrates to nitrites
  • motile by polar flagellum
37
Q

Test used to differentiate P. pseudoalcaligenes and P. alcaligenes

A

ADH

  • P. pseudoalcaligenes (+)
  • P. alcaligenes (-)
38
Q

Definitive differentiation of bacterial organisms.

A

MALDI-TOF and DNA sequencing

39
Q

Pseudomonas luteola &

Pseudomonas oryzihabitans

A
  • oxidase (-)
  • catalase (+)
  • motile, grow on MAC agar
  • oxidize glucose (+)
  • produce nondiffusible yellow pigment
  • produce wrinkled or rough colonies at 48 hrs.
40
Q

Acinetobacter spp.

A 
- 45% of patients with a tracheostomy may
be colonized
- Ventilator-associated pneumonia and
sepsis due to A. baumannii have a high
mortality rate
41
Q

Test used to differentiate A. baumannii and A. iwoffii

A

A. baumannii - glucose (+)
A. iwoffii - glucose (-)

  • both are nonhemolytic strain
42
Q

Acinetobacter Identifying characteristic

A
  • oxidase (-)
  • nonmotile
  • catalase (+)
  • resist decolonization & retain the crystal
    violet stain
43
Q

Characteristic of Acinobacter that could lead to misidentifiication of the certain bacteria

A

-resistance to decolorization & retention of crystal violet stain

44
Q

Acinetobacter spp produces _______ hue that resembles lactose-fermenting bacterium

A

PURPLISH HUE

45
Q

Stenotrophomonas maltophilia:

identifying characteristic

A
  • oxidase (-)
  • catalase (+)
  • BLUISH colonies on MAC agar
46
Q

Drug of choice for most Stenotrophomonas maltophilia infection.

A

SXT - Trimethoprim/sulfamethoxazole

47
Q

Risk factors for S. maltophilia

A
  • immunosppression

- hospitalization, presence of a central venous catheter (CVC)

48
Q

Burkholderia cepacia Complex

A
  • usually associated with
    pneumonia in patients with CF or CGD
  • cause endocarditis, pneumonitis, UTIs, osteomyelitis, dermatitis, and other wound infections resulting from the use of contaminated water
49
Q

Best selective medium for isolating B.cepacia

A

-BCSA

most effective in reducing overgrowth while maintaining good recovery of B.cepacia where non-wrinkled colonies are observed.

50
Q

Which biochemical tests are needed to differentiate Burkholderia cepacia from S. maltophilia? *

A. Pigment on blood agar, oxidase, DNase
B. Pigment on MacConkey agar, flagellar stain, motility
C. Glucose, maltose, lysine decarboxylase
D. TSI, motility, oxidase

A
  • A Pigment on blood agar, oxidase, DNase
51
Q

Burkholderia mallei

A
  • Causes “glanders”
  • nonmotile
  • oxidase (-)
  • a potential bioterrorism agent
    -broth microdilution with Brucella broth: as
    recommended by CLSI
  • a potential bioterrorism agent
52
Q

Burkholderia pseudomallei

A
  • causes MELIOIDOSIS/ Whitmore’s
    disease

most common presentation: orbital
cellulitis, dacryocystitis, & draining abscesses

53
Q

Burkholderia pseudomallei: Identifying characteristic

A

-uses lactose
- Selective medium: ASHDOWN MEDIUM (with colistin)
- deep pink colonies because of the
absorption of neutral red in the medium + earthy odor

54
Q

is an infectious disease that is caused by the bacterium Burkholderia mallei. While people can get the disease, glanders is primarily a disease affecting horses. It also affects donkeys and mules and can be naturally contracted by other mammals such as goats, dogs, and cats.

CGD
bacteremia
endocarditis
glanders
melioisis
none of the choices
A
  • Glanders

(a respiratory tract zoonosis
primarily affecting livestock such as horses, mules, &
donkeys)

55
Q

A 20-year-old horse groomer exhibited a“GLANDERS-like” infection. His history indicated he had suffered several open wounds on his hands 2 weeks before the swelling of his lymph nodes. A gram-negative rod was recovered from a blood culture that grew well on blood and McConkey agars. Most of the biochemical tests were negative, including the cytochrome oxidase test. What is the most likely identification?

A. Burkholderia mallei
B. Pseudomonas aeruginosa
C. Pseudomonas stutzeri
D. Burkholderia pseudomallei

A
  • A. Burkholderia mallei
56
Q

Which organism is associated with the disease MELIOIDOSIS? *

a. Burkholderia ralstonia
b. Burkholderia pseudomallei
c. Burkholderia mallei
d. Burkholderia cepacia

A
  • B Burkholderia pseudomallei

MELIOIDOSIS or Whitmore’s disease

57
Q

MELIOIDOSIS or Whitmore’s disease

A

an aggressive,
granulomatous, pulmonary disease
caused by ingestion, inhalation, or inoculation of
the organisms, with METASTATIC ABSCESS FORMATION
in lungs and other viscera

= overwhelming septicemia

58
Q

a potential bioterrorism agent(its occurrence should be reported to local or state public health depts)

Burkholderia mallei
Pseudomonas stutzeri
Oligella ureolytica
Psychrobacter
Moraxella spp.
A

-A. Burkholderia mallei

59
Q

Members of the family Moraxellaceae

A

Moraxella, Oligella, and Psychobacter

60
Q

Identifying characteristic:

Moraxella, Oligella, and Psychobacter

A
  • nonmotile
  • strongly oxidase (+)
  • asaccharolytic
    • strictly aerobic
    • usually susceptible to penicillin
    • are opportunists
61
Q

Oligella:

O. urethralis & O. ureolytica

A 
do not grow on MAC agar
• are nonoxidative
• phenylalanine deaminase (PDA) +
• oxidase (+)
• nitrate & nitrite + with gas formation
• susceptible to penicillin
62
Q

A motile organism by means of its peritrichous flagella, that causes bacteremia in AIDS patients is? *

O. urethralis
O. ureolytica
Stenotrophomonas maltophilia
Burkholderia mallei

A
  • O. ureolytica
63
Q

Identifying characteristic between:

O. urethralis & O. ureolytica

A

O. ureolytica

  • motile
  • peritrichous flagella
  • bacteremia in AIDS

O. urethralis

  • non-motile
  • genitourinary tract commensal
64
Q

Differentiation of Stenotrophomonas maltophilia and Burkholderia cepacia is best accomplished by which of the following tests? *

a. Oxidase test
b. Maltose and glucose medium
c. Tyrosine-enriched heart infusion agar
d. Growth at 42 C

A

a. Oxidase test

65
Q

Which tests are most appropriate to differentiate between Pseudomonas aeruginosa and Pseudomonas putida? *
A. Oxidase, motility, pyoverdin
B. Oxidase, motility, lactose
C. Oxidase, ONPG, DNase
D. Mannitol, nitrate reduction, growth at 42°C

A

D. Mannitol, nitrate reduction, growth at 42°C

  • P.putida
    - cannot grow on 42°C temp.
    - nitrate reduction (-)

BACTERIOLOGY (15 decks)

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