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

Bauman 6th Edition

Ch. 20 - Pathogenic Gram-Negative Cocci and Bacilli

Problem 1

Chapter 20, Problem 1

A physician prescribes fluid replacement to treat a patient with diarrhea. Although tests showed that a pathogenic enteric bacterium was the cause of the intestinal distress, an antimicrobial drug was not prescribed; why not?

Verified step by step guidance

Understand the context: The patient has diarrhea caused by a pathogenic enteric bacterium, which means the infection is in the intestines.

Recall that many cases of bacterial diarrhea are self-limiting, meaning they resolve on their own without the need for antibiotics.

Consider that antimicrobial drugs can disrupt the normal gut microbiota, potentially worsening the condition or leading to antibiotic resistance.

Recognize that fluid replacement is the primary treatment to prevent dehydration, which is the most immediate risk in diarrheal diseases.

Conclude that the physician likely avoided prescribing antimicrobials to prevent unnecessary side effects and resistance, focusing instead on supportive care with fluids.

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Key Concepts

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

Pathophysiology of Diarrhea

Diarrhea often results from the disruption of normal intestinal fluid absorption and secretion caused by enteric pathogens. Many bacteria cause diarrhea by producing toxins that alter ion transport, leading to fluid loss without necessarily requiring bacterial eradication for symptom resolution.

Role of Fluid Replacement Therapy

Fluid replacement is critical in treating diarrhea to prevent dehydration and electrolyte imbalance. Oral or intravenous rehydration restores lost fluids and salts, addressing the primary danger of diarrhea, often without needing to eliminate the causative bacteria immediately.

Antimicrobial Use and Resistance Considerations

Antimicrobial drugs are not always prescribed for enteric infections because many diarrheal illnesses are self-limiting, and unnecessary antibiotic use can promote resistance. Additionally, some bacterial toxins cause symptoms even after bacteria are cleared, so antibiotics may not improve outcomes.

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Antimicrobial Peptides

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

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

Label the following drawing using these words: adhesin, exotoxin, H antigens, hemolysin, iron-binding protein, K antigens, outer membrane (with common antigen, lipid A, and O antigen), fimbria, plasmid virulence genes, type III secretion system.

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Textbook Question

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

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Textbook Question

The presence of lipid A in the outer membranes of Gram-negative bacteria.

a. Affects the formation of blood clots in the host

b. Causes these bacteria to be oxidase positive

c. Triggers the secretion of a protease enzyme to cleave IgA in mucus

d. Enables enteric bacteria to ferment glucose anaerobically

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