Choose the general agent of the disease (select ONE choice of agent from the options after each illness):
a. Pneumococcal pneumonia is caused by a (virus, bacterium, fungus).
b. Pneumocystis pneumonia is caused by a (virus, bacterium, fungus).
c. Tuberculosis is caused by a (virus, bacterium, fungus).
d. Histoplasmosis is caused by a (virus, bacterium, fungus).
e. Influenza is caused by a (virus, bacterium, fungus).
f. Colds are caused by (viruses, bacteria, fungi).
g. Coccidioidomycosis is caused by a (virus, bacterium, fungus).
h. Diphtheria is caused by a (virus, bacterium, fungus).
i. Pertussis is caused by a (virus, bacterium, fungus).
j. Scarlet fever is caused by a (virus, bacterium, fungus).
k. Legionellosis is caused by a (virus, bacterium, fungus).
l. Q fever is caused by a (virus, bacterium, fungus).
m. Hanta pulmonary syndrome is caused by a (virus, bacterium, fungus).
n. Streptococcal pharyngitis is caused by a (virus, bacterium, fungus).

Verified step by step guidance

1. Step 1: Understand the three categories of infectious agents: viruses, bacteria, and fungi. Viruses are acellular pathogens that require host cells to replicate. Bacteria are unicellular prokaryotes that can cause a wide range of diseases. Fungi are eukaryotic organisms that can cause infections, especially in immunocompromised individuals.
2. Step 2: For each disease, identify the typical causative agent based on microbiological knowledge: Pneumococcal pneumonia is caused by Streptococcus pneumoniae, which is a bacterium.
3. Step 3: Pneumocystis pneumonia is caused by Pneumocystis jirovecii, which is classified as a fungus, even though it was once thought to be a protozoan.
4. Step 4: Tuberculosis is caused by Mycobacterium tuberculosis, a bacterium; Histoplasmosis and Coccidioidomycosis are fungal infections caused by Histoplasma capsulatum and Coccidioides species respectively.
5. Step 5: Influenza and Hanta pulmonary syndrome are viral diseases; Diphtheria, Pertussis, Scarlet fever, Legionellosis, Q fever, and Streptococcal pharyngitis are caused by bacteria; common colds are caused by viruses.

Key Concepts

Classification of Microbial Agents

Microbial agents causing diseases are broadly classified into viruses, bacteria, and fungi. Viruses are acellular entities requiring host cells to replicate, bacteria are unicellular prokaryotes with diverse metabolic capabilities, and fungi are eukaryotic organisms that can be unicellular or multicellular. Understanding these categories helps identify the nature of the pathogen responsible for specific diseases.

Common Respiratory Pathogens and Their Disease Associations

Many respiratory diseases are caused by specific pathogens: bacteria like Streptococcus pneumoniae cause pneumococcal pneumonia; fungi such as Histoplasma capsulatum cause histoplasmosis; viruses like influenza virus cause influenza. Recognizing which type of microbe typically causes each illness aids in diagnosis and treatment decisions.

Differences Between Viral, Bacterial, and Fungal Pneumonias

Pneumonias can be caused by viruses, bacteria, or fungi, each with distinct clinical features and treatment approaches. Bacterial pneumonias often present with localized lung consolidation, viral pneumonias may cause diffuse inflammation, and fungal pneumonias typically occur in immunocompromised hosts. Identifying the causative agent type is crucial for effective therapy.