Deck 20: Pseudomonas, Burkholderia, and Similar Organisms

Question 1

Production of exotoxin A and several proteolytic enzymes and hemolysins are factors that contribute to the pathogenicity of which organism?

A)P.aeruginosa
B)Burkholderia cepacia
C)Ralstonia pickettii
D)Burkholderia mallei

Answer 1

A
Although P.aeruginosa is an environmental inhabitant,it is also a successful opportunistic pathogen.Factors that contribute to pathogenicity include the production of exotoxin A,which kills host cells by inhibiting protein synthesis,and the production of several proteolytic enzymes and hemolysins that destroy cells and tissue.On the bacterial cell surface,pili may mediate attachment to host cells.Some strains produce alginate,a polysaccharide polymer that inhibits phagocytosis and contributes to infection potential in patients with cystic fibrosis.

Question 2

Which occupation would hold highest risk of glanders?

A)Rice farmer
B)Medical doctor
C)Veterinarian
D)Sewer worker

Answer 2

C
Glanders is an infection found in horses,mules,and donkeys,as well as in other animals caused by B.mallei.Humans (e.g. ,veterinarians,farriers,other animal workers,and laboratory personnel)in close contact with infected animals or contaminated objects may become infected.Bacteria enter through wounds or cuts or through eyes and nose.

Question 3

In addition to cystic fibrosis patients,patients with which other disease are at greatest risk of death due to fulminant lung infections and/or bacteremia caused by B.cepacia?

A)Cardiovascular disease
B)Chronic kidney disease
C)Chronic obstructive pulmonary disease
D)Chronic granulomatous disease

Answer 3

D
In patients with cystic fibrosis or chronic granulomatous disease,the organism can cause fulminant lung infections and bacteremia,resulting in death.In other patient populations,infections of the blood,urinary tract,and respiratory tract usually result from exposure to contaminated medical solutions or devices but are rarely fatal.

Question 4

Which organism exhibits bipolar staining on the Gram stain,which resembles a "safety-pin" appearance?

A)B.mallei
B)B.pseudomallei
C)B.diminuta
D)B.vesicularis

Question 5

A weakly oxidase-positive,nonfermenting gram-negative rod is isolated from respiratory sample.Traditional biochemical reactions include: arginine dihydrolase-negative;lysine decarboxylase-positive;gelatin liquefaction-positive;oxidizes lactose and glucose.

A)B.cepacia
B)B.vesicularis
C)P.aeruginosa
D)Pandoraea spp.

Question 6

Which two organisms should be used to determine the validity of urea agar for quality control purposes?

A)P.fluorescens and B.cepacia complex
B)Ralstonia mannitolilytica and Acidovorax delafieldii
C)Brevundimonas diminuta and Brevundimonas vesicularis
D)B.vesicularis and R.pickettii

Question 7

Oxidative-fermentative base-polymyxin B-bacitracin-lactose (OFPBL)media is the best media to use to isolate which one of the following organisms from the sputa of patients with cystic fibrosis?

A)A.delafieldii
B)R.pickettii
C)B.cepacia
D)B.pseudomallei

Question 8

In some immunocompromised patients,bacteremia caused by P.aeruginosa can invade and destroy the walls of subcutaneous blood vessels,resulting in the formation of cutaneous papules that become black and necrotic.This condition is known as:

A)nodular folliculitis
B)ecthyma gangrenosum
C)malignant otitis externa
D)necrolytic migratory erythema

Question 9

What condition is most likely when P.fluorescens,P.putida,or P.stutzeri,Brevundimonas spp. ,and Ralstonia spp.are isolated from respiratory specimens?

A)Person-to-person transmission should be suspected.
B)Specimens come from immunocompetent individuals.
C)The isolated bacteria may not represent a significant pathogen.
D)The patient is in need of a lung transplant.

Question 10

Nonfermenting gram-negative rods isolated from respiratory samples from cystic fibrosis patients are difficult to identify using commercial systems.Thus,other testing platforms are being used to aid in accurate species identification.Which of the following systems has the advantage of a large curated database of proteomic profiles representative of many microorganisms and can give definitive organism identification within minutes?

A)Cellular fatty acid analysis
B)MALDI-TOF mass spectrometry
C)Multilocus sequence typing
D)Ribotyping of 16S rRNA gene

Question 11

Which of the following Ralstonia spp.most often causes infections in cystic fibrosis patients?

A)Ralstonia gilardii
B)Ralstonia insidiosa
C)R.mannitolilytica
D)R.pickettii

Question 12

An organism described as oxidase-positive,(K/NC)on TSI media,growth at 42°C,and produces a bright bluish-green pigment on Mueller-Hinton agar is most likely:

A)P.aeruginosa.
B)Pseudomonas fluorescens
C)B.cepacia
D)B.mallei.

Question 13

A convenient and reliable identification scheme for P.aeruginosa involves which of the following conventional tests?

A)Oxidase,triple sugar iron (TSI)slant,growth at 42°C on Mueller-Hinton agar or trypticase soy agar
B)Catalase,lysine iron agar (LIA)slant,growth at 42°C on Mueller-Hinton agar or trypticase soy agar
C)Oxidase,TSI slant,growth at 24°C on Mueller-Hinton agar or trypticase soy agar
D)Catalase,TSI slant,growth at 42°C on sheep blood agar or blood trypticase soy agar

Question 14

Not including organisms in the Enterobacteriaceae family,the most common gram-negative bacilli encountered in clinical specimens are:

A)Pseudomonas.
B)Burkholderia.
C)Ralstonia.
D)Vibrio.

Question 15

A flagella stain was performed;no flagella were seen.Which of the following bacterium would be consistent with negative flagella stain result?

A)B.mallei
B)B.vesicularis
C)P.fluorescens
D)R.pickettii

Question 16

The disease referred to as melioidosis is caused by which one of the following?

A)P.aeruginosa
B)R.pickettii
C)B.mallei
D)Burkholderia pseudomallei

Question 17

Which best describes the source of B.cepacia infections?

A)Rice paddies
B)Medical devices
C)Oropharynx of animals
D)Rodents

Question 18

Which of the following statements is true about susceptibility testing or treatment of P.aeruginosa?

A)Susceptibility testing is required to detect intrinsic resistance.
B)Repeat susceptibility testing may be needed to monitor development of resistance.
C)Susceptibility testing of isolates from cystic fibrosis patients following standard protocols gives reliable results.
D)Treatment with a single antimicrobial agent,such as b-lactam with antipseudomonal activity,is recommended.

Question 19

Overproduction of what substance is associated with biofilm production and mucoid phenotype of P.aeruginosa isolates found in cystic fibrosis patients?

A)Alginate
B)Exoenzyme T
C)Phospholipase C
D)Pyocyanin

Question 20

Which species of Burkholderia is the one most commonly found in clinical specimens?

A)Burkholderia ralstonia
B)B.pseudomallei
C)B.mallei
D)B.cepacia

Question 21

Which of the following groups of bacteria have Clinical Laboratory Standards Institute (CLSI)guidelines that describe specific testing methods and interpretative standards for susceptibility reporting?

A)A.facilis and Stenotrophomonas maltophilia
B)P.fluorescens and R.mannitolilytica
C)P.aeruginosa and B.pseudomallei
D)B.cepacia and B.vesicularis

Question 22

Which combination of nonfermenting gram-negative bacilli are oxidase positive,but do not grow on MacConkey agar within 24 to 48 hours.

A)B.cepacia and Pseudomonas stutzeri
B)Brevundimonas dimunuta and Pseudomonas veronii
C)P.aeruginosa and R.insidiosa
D)B.vesicularis and Acidovorax facilis

Question 23

PC agar is a selective media for isolation of B.cepacia.What is the purpose of the polymixin B and ticarcillin in the media?

A)They provide nutrients to enrich the growth of B.cepacia.
B)They cause color change in the media from yellow to pink.
C)They inhibit growth of gram-positive and other gram-negative organisms.
D)They stabilize the media to support growth if prolonged incubation is needed.

Question 24

Preferred samples for plating onto Ashdown media include throat,rectal,or sputum samples.Disease presentation can range from subclinical to disseminated disease.This infection is endemic in Southeast Asia.Which organism is being sought?

A)B.cepacia
B)Burkholderia gladioli
C)B.mallei
D)B.pseudomallei

Question 25

The following species,P.aeruginosa,P.fluorescens,Pseudomonas putida,P.veronii,Pseudomonas monteilii,and Pseudomonas mosselii,all produce a water-soluble,yellow-green pigment called:

A)pyocyanin.
B)pyomelanin.
C)pyorubrum.
D)pyoverdin.