Aerobic Gram Positive Rods

Which of the following is associated with infections in humans often linked to deli meats and improperly pasteurized dairy products?

Listeria monocytogenes

Tellurite reduction is used for the presumptive identification of

Corynebacterium diphtheriae

The description of "Medusa head" colonies on solid agar is most characteristic of

Bacillus anthracis

Colonies of Listeria monocytogenes on a sheep blood agar plate most closely resemble colonies of

Streptococcus agalactiae

Pleomorphic gram-positive bacilli in a Gram stain best describes

Corynebacterium pseudodiphtheriticum

The pulmonary form of anthrax is known as

Woolsorters disease

Cystine-tellurite blood agar plates are recommended for the isolation of

Corynebacterium diphtheriae

Which of the following species of Bacillus is nonmotile?

B. anthracis

Which of the following is not characteristic of Listeria monocytogenes?

Catalase negative

Growth in a 48-hour semisolid agar stab culture at room temperature reveals lateral filamentous growth away from the stab near the top of the medium. This observation is most characteristic of which organism?

Listeria monocytogenes

The production of H2S is one characteristic used to differentiate which of the aerobic gram-positive bacilli?

Erysipelothrix

Precipitates of diphtheria toxin and antitoxin formed in agar gels are an in vitro means for detecting toxigenic strains of Corynebacterium diphtheriae. The name of this test procedure is the

Elek test

On Tinsdale agar, colonies of Corynebacterium diphtheriae are characterized by the observance of

Black colonies on the culture medium surrounded by brown halos

Loeffler's serum medium is recommended for the cultivation of

Corynebacterium diphtheriae

Which of the following is the most commonly isolated species of Bacillus in opportunistic infections such as bacteremia, post-traumatic infections of the eye, and endocarditis?

B. cereus

Color Plate 26 shows the Gram stain of a blood culture on a 23-year-old pregnant woman who presented with fever and flulike symptoms in her ninth month. The isolate on blood agar produced small. Translucent beta-hemolytic colonies. Which of the following is the most likely etiologic agent in this case?

Listeria monocytogens

Erysipelothrix infections in humans characteristically produce

Pathology at the point of entrance of the organism

The organism associated with a disease characterized by the presence of a pseudomembrane in the throat and the production of an exotoxin that is absorbed into the bloodstream with a lethal effect is

Corynebacterium diphtheriae

Large gram-positive spore-forming rods growing on blood agar as large, raised, β-hemolytic colonies that spread and appear as frosted green-gray glass are most likely

Bacillus spp

Bacillus anthracis and Bacillus cereus can best be differentiated by which tests?

Motility and β-hemolysis on a blood agar plate

Which is the specimen of choice for proof of food poisoning by Bacillus cereus?

Food

A suspected Bacillus anthracis culture obtained from a wound specimen produced colonies that had many outgrowths (Medusa-head appearance), but were not β-hemolytic on sheep blood agar. Which test should be performed next?

Penicillin (10-unit) susceptibility test

Which of the following tests should be performed for initial differentiation of Listeria monocytogenes from group B streptococci?

Gram stain, motility at room temperature, catalase

Culture of a finger wound specimen from a meat packer produced short gram-positive bacilli on a blood agar plate with no hemolysis. Given the following test results at 48 hours, what is the most likely identification?

Catalase = Neg H2S/TSI = +

Motility (wet prep) = Neg

Motility (media) = Neg (bottle-brush growth in stab

culture)

Erysipelothrix rhusiopathiae

A Corynebacterium species recovered from a throat culture is considered a pathogen when it produces:

All of these options

3 multiple choice options

A non-spore-forming, slender gram-positive rod forming palisades and chains was recovered from a vaginal culture and grew well on tomato juice agar. The most likely identification is:

Lactobacillus spp.

A presumptive diagnosis of Gardnerella vaginalis can be made using which of the following findings?

All of these options

3 multiple choice options

A gram-positive branching filamentous organism recovered from a sputum specimen was found to be positive with a modified acid-fast stain method. What is the most likely presumptive identification?

Nocardia spp.

Which of the following is the best, rapid, noncultural test to perform when Gardnerella vaginalis is suspected in a patient with vaginosis?

10% KOH test

A direct smear from a nasopharyngeal swab stained with Loeffler methylene blue stain showed various letter shapes and deep blue, metachromatic granules. The most likely identification is:

Corynebacterium spp.

Bacillus

Diphteroids

Listeria

Erysiphelotrix

Bacillus antracis

False

Corynebacterium diphteriae is typically used as QC for autoclave

False

Catalase Positive

Listeria

Colony morphology resembles Strep B

Listeria

DPT vaccine, exotoxin

C.diphteriae