Chapter 7.3 - Nonfermentative Bacilli (HARR)

Oxidase, TSI, nitrate reduction, growth on MacConkey agar

Oxidase, TSI, nitrate reduction, growth on MacConkey agar

What are the most appropriate screening tests to presumptively differentiate and identify the nonfermentative gram-negative bacilli (NFB) from the Enterobacteriaceae?

Oxidase, oxidation–fermentation (OF) glucose (open), OF glucose (sealed), motility, pigment production

Presumptive tests used for identification of the Pseudomonas spp. are:

Mannitol, nitrate reduction, growth at 42°C

Which tests are most appropriate to differentiate between Pseudomonas aeruginosa and Pseudomonas putida?

Oxidase, motility, NO3 reduction

Which test group best differentiates Acinetobacter baumannii from P. aeruginosa?

Oxidase

In addition to motility, which test best differentiates Acinetobacter spp. and Alcaligenes spp.?

Oxidase, 42°C growth, and polar tuft of flagella

The most noted differences between P. aeruginosa and Stenotrophomonas maltophilia are:

P. aeruginosa

Which Pseudomonas is usually associated with a lung infection related to cystic fibrosis?

Pseudomonas stutzeri

A nonfermenter recovered from an eye wound is oxidase positive, motile with polar monotrichous flagella, and grows at 42°C. Colonies are dry, wrinkled or smooth, buff to light brown in color, and are difficult to remove from the agar. In which DNA homology group should this organism be placed?

Burkholderia pseudomallei

Which organism is associated with immunodeficiency syndromes and melioidosis (a glanders-like disease in Southeast Asia and northern Australia)?

Pigment on blood agar, oxidase, DNase

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

Urease (rapid)

Alcaligenes faecalis (formerly A. odorans) is distinguished from Bordetella bronchiseptica with which test?

Oxidase, growth on MacConkey agar

Chryseobacterium spp. are easily distinguished from Acinetobacter spp. by which of the following two tests?

Moraxella lacunata

A gram-negative coccobacillus was recovered on chocolate agar from the CSF of an immunosuppressed patient. The organism was nonmotile and positive for indophenol oxidase but failed to grow on MacConkey agar. The organism was highly susceptible to penicillin. The most probable identification is:

Pseudomonas aeruginosa

Cetrimide agar is used as a selective isolation agar for which organism?

Pseudomonas aeruginosa

A specimen from a 15-year-old female burn patient was cultured after débridement, and the following results were obtained:

Oxidase = +

Lysine decarboxylase = Neg

Catalase = +

Motility = +

Ornithine decarboxylase = Neg

Glucose = + for oxidation (open tube)

Arginine dihydrolase = +

Maltose = Neg for oxidation (open tube)

Penicillin = Resistant

Aminoglycosides = Susceptible

Colistin (Polymixin B) = Susceptible

These results indicate which of the following organisms?

Chryseobacterium meningosepticum

A yellow pigment–producing organism that is oxidase positive, nonmotile, and does not grow on MacConkey agar is:

Sulfanilic acid and α-naphthylamine

Which reagent(s) is (are) used to develop the red color indicative of a positive reaction in the nitrate reduction test?

Shewanella putrefaciens

A culture from an intra-abdominal abscess produced orange-tan colonies on blood agar that gave the following results:

Oxidase = +

Nitrate reduction = +

KIA = Alk/Alk (H2S)+

Motility = + (single polar flagellum)

DNase = +

Ornithine decarboxylase = +

Growth at 42°C = Neg

The most likely identification is:

Motility

Chryseobacterium spp. and B. cepacia are easily differentiated by which test?

P. aeruginosa

Which of the listed Pseudomonas spp. is associated with the following virulence factors: exotoxin A, endotoxins, proteolytic enzymes, antimicrobial resistance, and production of alginate?

Burkholderia pseudomallei

A Vietnam War veteran presented with a “glanders-like” infection (melioidosis). Several blood cultures produced gram-negative rods that were positive for cytochrome oxidase, oxidized glucose and xylose, and grew at 42°C. What is the most likely organism?

Pseudomonas aeruginosa

Cytochrome oxidase-positive, nonfermentative gram-negative bacilli were recovered from the stool of a cystic fibrosis (CF) patient. The isolates produced wet (mucoidy) colonies on blood agar. Which identification is most likely?