Question 1

Which organism exhibits bipolar staining on the Gram stain, which resembles a &#34;safety-pin&#34; appearance?&#10;A) Burkholderia mallei&#10;B) Pseudomonas pseudomallei&#10;C) The Centers for Disease Control and Prevention (CDC) group&#10;D) Brevundimonas diminuta

Accepted Answer

P.pseudomallei exhibits bipolar staining on Gram stain that resembles a safety-pin appearance.

Question 2

Which two organisms should be used to determine the validity of urea agar for quality control purposes?&#10;A) Pseudomonas fluorescens and Burkholderia cepacia complex&#10;B) Ralstonia mannitolilytica and Acidovorax delafieldii&#10;C) Brevundimonas diminuta and Brevundimonas vesicularis&#10;D) Brevundimonas vesicularis and Ralstonia pickettii

Accepted Answer

The only two organisms that are negative and positive, respectively, are B.vesicularis and R.pickettii, and they can be used for quality control purposes.

Question 3

An organism described as oxidase-positive, (K/NC)on TSI media, growth at 42&#176; C, and produces a bright bluish-green pigment on Mueller-Hinton agar is most likely:&#10;A) Pseudomonas aeruginosa.&#10;B) Ralstonia pickettii.&#10;C) Burkholderia mallei.&#10;D) Burkholderia pseudomallei.

Accepted Answer

P.aeruginosa, one of the most common gram-negative species encountered in the clinical setting, can be identified conveniently and reliably by the oxidase test, TSI slant, testing for growth at 42° C, and observation of a bright bluish-green, red, or brown diffusible pigment.

Question 4

Which best describes the source of Burkholderia cepacia infections?&#10;A) Rice paddles&#10;B) Medical devices&#10;C) Oropharynx of animals&#10;D) Rodents

Accepted Answer

Plants, soil, and water serve as reservoirs of B.cepacia.This organism is able to survive on or in medical devices and disinfectants.Human acquisition of B.cepacia, resulting in colonization or infection, usually involves direct contact with contaminated foods; medical solutions, including disinfectants; and devices, such as respiratory equipment.Alternatively, person-to-person transmission also has been documented.

Question 5

A convenient and reliable identification scheme for Pseudomonas aeruginosa involves which of the following conventional tests?&#10;A) Oxidase, triple sugar iron (TSI) slant, growth at 42&#176; C on Mueller-Hinton agar or trypticase soy agar&#10;B) Catalase, lysine iron agar (LIA) slant, growth at 42&#176; C on Mueller-Hinton agar or trypticase soy agar&#10;C) Oxidase, TSI slant, growth at 24&#176; C on Mueller-Hinton agar or trypticase soy agar&#10;D) Catalase, TSI slant, growth at 42&#176; C on sheep blood agar or blood trypticase soy agar

Accepted Answer

P.aeruginosa is one of the most common gram-negative species encountered in the clinical setting.A convenient and reliable identification scheme for this pathogen is helpful and includes the oxidase test, TSI slant, testing for growth at 42° C, and observation of a bright bluish-green, red, or brown diffusible pigment.

Question 6

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?&#10;A) Pseudomonas pseudomallei&#10;B) Ralstonia pickettii&#10;C) Burkholderia cepacia&#10;D) Acidovorax delafieldii

Accepted Answer

OFPBL is a selective media used to isolate B.cepacia in patients with cystic fibrosis.OFPBL incorporates bacitracin as an added selective agent and uses lactose fermentation to differentiate isolates.B.cepacia ferments lactose and appears yellow, whereas nonfermenters appear green.

Question 7

Not including organisms in the Enterobacteriaceae family, the second most common gram-negative bacilli encountered in clinical specimens are:&#10;A) Pseudomonas.&#10;B) Burkholderia.&#10;C) Ralstonia.&#10;D) Vibrio.

Accepted Answer

Pseudomonas is the second most common gram-negative bacilli encountered in clinical specimens, after the organisms in the Enterobacteriaceae family. Burkholderia and Ralstonia are less frequently encountered, and Vibrio is primarily associated with water-related infections.

Question 8

The disease referred to as melioidosis is caused by which one of the following?&#10;A) Pseudomonas aeruginosa&#10;B) Ralstonia pickettii&#10;C) Burkholderia mallei&#10;D) Burkholderia pseudomallei

Accepted Answer

Infections caused by B.pseudomallei, which can survive in human macrophages, can range from being asymptomatic to severe.The disease is referred to as melioidosis; it has several forms, including formation of skin abscesses, sepsis and septic shock, abscess formation in several internal organs, and acute pulmonary disease.

Question 9

Which species of Burkholderia is the one most commonly found in clinical specimens?&#10;A) Burkholderia ralstonia&#10;B) Burkholderia pseudomallei&#10;C) Burkholderia mallei&#10;D) Burkholderia cepacia

Accepted Answer

B.cepacia is the species most commonly found in clinical specimens.This organism is able to survive on or in medical devices and disinfectants.An intrinsic resistance to multiple antimicrobial agents also contributes to this organism's survival in hospitals.

Question 10

Production of exotoxin A and several proteolytic enzymes and hemolysins are factors that contribute to the pathogenicity of which organism?&#10;A) Pseudomonas aeruginosa&#10;B) Burkholderia cepacia&#10;C) Ralstonia pickettii&#10;D) Burkholderia mallei

Accepted Answer

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.

Deck 21: Pseudomonas, Burkholderia, and Similar Organisms