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Ch. 20 - Pathogenic Gram-Negative Cocci and Bacilli
Bauman - Microbiology with Diseases by Taxonomy 6th Edition
Bauman6th EditionMicrobiology with Diseases by TaxonomyISBN: 9780134832302Not the one you use?Change textbook
All textbooksBauman 6th EditionCh. 20 - Pathogenic Gram-Negative Cocci and BacilliProblem 2
Chapter 20, Problem 2

The only genus of Gram-negative cocci that causes significant disease in humans is
a. Pasteurella
b. Salmonella
c. Klebsiella
d. Neisseria

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1
Understand the question is asking for the genus of Gram-negative cocci that is medically significant in humans.
Recall that Gram-negative bacteria are classified by shape: cocci (spherical), bacilli (rod-shaped), etc.
Identify which of the listed genera are Gram-negative cocci: Pasteurella, Salmonella, Klebsiella, and Neisseria.
Recognize that Pasteurella, Salmonella, and Klebsiella are Gram-negative rods, not cocci.
Know that Neisseria is the only genus among the options that consists of Gram-negative cocci and includes important human pathogens like Neisseria gonorrhoeae and Neisseria meningitidis.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Gram-negative Cocci

Gram-negative cocci are spherical bacteria that do not retain the crystal violet stain during Gram staining, appearing pink under a microscope. They are less common than Gram-positive cocci and include genera like Neisseria, which are important in human disease.
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Gram-Negative Cell Walls

Pathogenic Genera of Gram-negative Bacteria

Among Gram-negative bacteria, certain genera are known for causing human diseases. While many are rod-shaped (bacilli), only a few cocci genera, notably Neisseria, are significant pathogens, causing diseases such as meningitis and gonorrhea.
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Neisseria as a Human Pathogen

Neisseria is the only genus of Gram-negative cocci that includes species causing major human diseases, like Neisseria meningitidis (meningitis) and Neisseria gonorrhoeae (gonorrhea). Its unique pathogenicity distinguishes it from other Gram-negative bacteria.
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Related Practice
Textbook Question

Match each bacterium with the disease or manifestations it causes.


1. _____ Escherichia coli

2. _____ Klebsiella pneumoniae

3. _____ Proteus mirabilis

4. _____ Salmonella enterica serotype Typhi

5. _____ Shigella flexneri

6. _____ Yersinia pestis


A. Bubonic plague

B. Typhoid fever

C. Gastroenteritis

D. Kidney stones

E. Pus-filled, bloody stools; cramps; fever; and diarrhea

F. Pneumonia

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Textbook Question

Which of the following bacterial cells is most likely to be virulent?

a. A cell with fimbriae and LOS

b. A cell with a polysaccharide capsule and lipooligosaccharide

c. A cell with fimbriae, lipooligosaccharide, and a polysaccharide capsule

d. A cell with fimbriae but no capsule

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Textbook Question

Shown is a MacConkey agar plate. Describe the Gram reaction and lactose fermentation of the two different bacteria shown.

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Textbook Question

Why do nurses place antimicrobial agents in babies’ eyes at birth?

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Textbook Question

Which of the following statements is true?

a. PID is a severe type of diarrhea in which infection spreads from the intestines to

the bloodstream.

b. PID can result from Neisseria infection.

c. PID is more common in men than women.

d. Members of the family Enterobacteriaceae usually cause PID.

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Textbook Question

Distinguish among the pathogenicity of coliforms, noncoliforms, and truly pathogenic enteric bacteria.

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