Question

Name three bacteria that commonly cause pneumonia. Which is the most common cause?

Short answer

Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae. The most common cause is Streptococcus pneumoniae.

Step-by-step solution

Identify the Bacteria

The first step is to identify three bacteria that are known to commonly cause pneumonia. These bacteria are Streptococcus pneumoniae, Haemophilus influenzae, and Mycoplasma pneumoniae.

Determine the Most Common Cause

Out of the identified bacteria, determine which one is the most frequent cause of pneumonia. Streptococcus pneumoniae is the most common cause of pneumonia.

Key concepts

Streptococcus pneumoniae

Streptococcus pneumoniae is a leading cause of bacterial pneumonia. It is a gram-positive bacterium that often colonizes the respiratory tract. People with compromised immune systems, like the elderly or very young children, are particularly vulnerable.

Pneumonia caused by Streptococcus pneumoniae is often severe, presenting symptoms such as:

• High fever
• Chills
• Productive cough with yellow or green phlegm
• Chest pain

Treatment usually involves antibiotics, and vaccines are available to prevent pneumococcal infections.

Haemophilus influenzae

Haemophilus influenzae is another significant bacterium responsible for pneumonia. Unlike Streptococcus pneumoniae, it is a gram-negative bacterium. It mainly affects children and is less common in adults.

Symptoms of Haemophilus influenzae-caused pneumonia include:

• Fever
• Shortness of breath
• Cough with phlegm
• Fatigue

Antibiotics are typically effective against this type of bacteria, and prevention can be achieved through vaccination. The Hib vaccine has significantly reduced cases of Haemophilus influenzae type b infections.

Mycoplasma pneumoniae

Mycoplasma pneumoniae causes what's known as 'walking pneumonia', which tends to be less severe than other forms. This bacterium doesn't have a cell wall, which makes it unique and more difficult to treat with standard antibiotics that target cell wall synthesis.

Symptoms usually include:

• Low-grade fever
• Persistent dry cough
• Sore throat
• Headache

Treatment often involves a different class of antibiotics like macrolides, tetracyclines, or fluoroquinolones. Because the symptoms are milder, people with Mycoplasma pneumoniae can often continue with their daily activities, hence the term 'walking pneumonia.'