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Ch. 23 - Microbial Diseases of the Cardiovascular and Lymphatic Systems
Tortora - Microbiology: An Introduction 14th Edition
Tortora14th EditionMicrobiology: An IntroductionISBN: 9780138200398Not the one you use?Change textbook
All textbooksTortora 14th EditionCh. 23 - Microbial Diseases of the Cardiovascular and Lymphatic SystemsProblem 1
Chapter 23, Problem 1

Use the following choices to answer the question given below:
a. Ehrlichiosis
b. Lyme disease
c. Septic shock
d. Toxoplasmosis
e. Viral hemorrhagic fever
A patient presents with a history of fever and headache. Bacterial cultures of blood, CSF, and stool are negative. What is your diagnosis?

Verified step by step guidance
1
Step 1: Analyze the patient's symptoms and test results. The patient has fever and headache, which are common symptoms in many infections, but bacterial cultures of blood, cerebrospinal fluid (CSF), and stool are negative, suggesting the infection is not caused by typical bacteria detectable in these samples.
Step 2: Review the list of possible diagnoses: a. ehrlichiosis, b. Lyme disease, c. septic shock, d. toxoplasmosis, e. viral hemorrhagic fever. Consider which of these conditions typically present with fever and headache but do not usually yield positive bacterial cultures in blood, CSF, or stool.
Step 3: Understand that septic shock (option c) is a severe systemic response to bacterial infection and would likely have positive bacterial cultures, so it is less likely here.
Step 4: Recognize that ehrlichiosis (option a) and Lyme disease (option b) are tick-borne illnesses caused by bacteria that are difficult to culture using standard methods, often leading to negative bacterial cultures despite infection.
Step 5: Consider toxoplasmosis (option d) and viral hemorrhagic fever (option e), which are caused by protozoa and viruses respectively, and would not show positive bacterial cultures. Use clinical context and epidemiology to narrow down the diagnosis.

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Key Concepts

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

Differential Diagnosis of Fever and Headache

Fever and headache are common symptoms with many causes, including infections. When bacterial cultures are negative, it suggests a non-bacterial cause such as viral, parasitic, or tick-borne diseases. Understanding the range of possible etiologies helps narrow down the diagnosis.
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Limitations of Bacterial Cultures

Bacterial cultures detect bacterial pathogens in blood, CSF, or stool but cannot identify viral or certain parasitic infections. Negative cultures indicate that bacteria are unlikely the cause, prompting consideration of other infectious agents like viruses or intracellular bacteria that require different diagnostic methods.
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Characteristics of Tick-borne and Parasitic Diseases

Diseases like ehrlichiosis, Lyme disease, and toxoplasmosis often present with fever and headache but may not show positive bacterial cultures. These infections are caused by intracellular bacteria or parasites, requiring serology or molecular tests for diagnosis, and are important considerations when cultures are negative.
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Related Practice
Textbook Question

Use the following choices to answer the question given below:

a. Ehrlichiosis

b. Lyme disease

c. Septic shock

d. Toxoplasmosis

e. Viral hemorrhagic fever

A patient was hospitalized because of continuing fever and progression of symptoms including headache, fatigue, and back pain. Tests for antibodies to B. burgdorferi were negative. What is your diagnosis?

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Textbook Question

Use the following choices to answer the question given below:

a. Ehrlichiosis

b. Lyme disease

c. Septic shock

d. Toxoplasmosis

e. Viral hemorrhagic fever

A patient complained of headache. A CT (computed tomography) scan revealed cysts of varying size in the patient’s brain. What is your diagnosis?

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Textbook Question

Complete the following table.

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Textbook Question

Show the path of Streptococcus from a focal infection to the pericardium. Identify the portals of entry for T. cruzi, Orthohantavirus, and Cytomegalovirus.

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