MMIC PBL

Particulars of patient
Name: Tong Wei Hong
Sex: Male
Age: 68 years

Clinical diagnosis
Complaints: Fever, chills, excessive phlegm, breathing problems
Diagnosis: Bronchitis

Bronchitis is inflammation of the large airways that branch off the trachea (bronchi), usually caused by infection but sometimes caused by irritation from a gas or particle.

In bronchitis, areas of the bronchial wall become inflamed and swollen, and mucus increases. As a result, the air passageway is narrowed. Bacteria and viruses are usually present.

There are two main types of bronchitis:

-Acute bronchitis comes on rapidly, usually after a virus has invaded the upper respiratory tract. Sometimes there is a bacterial infection as well. Viruses most likely to trigger acute bronchitis are those responsible for influenza (the flu) or the common cold.

-Chronic bronchitis is defined as excessive mucus secretion in the bronchi and a chronic or recurrent mucus-producing cough that lasts three or more months and recurs year after year. People who have chronic bronchitis are more susceptible to bacterial infections of the airway and lungs, like pneumonia.

Mycoplasma pneumoniae and Chlamydia pneumoniae often cause bacterial bronchitis in young adults. Among middle-aged and older people, Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis are the most common organisms causing bacterial bronchitis.

Viral bronchitis may be caused by a number of common viruses, including the influenza virus (influenza A and B). A person often has a combination of bacterial and viral bronchitis.

Possible causative agents

The below 3 microorganisms often cause bacterial bronchitis in middle-aged and older people.

Possible Microorganisms	Description
Streptococcus pneumoniae	-Gram-positive -Alpha-hemolytic diplococcus bacterium -Members of the genus Streptococcus -Found in the nasopharynx -Major cause of pneumonia
Haemophilus influenzae	-Non-motile gram-negative coccobacillus -Found in the upper respiratory system of humans -Major cause of lower respiratory tract infections, associated with pneumonia
Moraxella catarrhalis	-Gram-negative, aerobic, oxidase-positive diplococcus cocci -Major cause of respiratory tract-associated infection, associated with bronchopneumonia

Investigation required

Specimen: Sputum
*Clear or white sputum suggests a viral infection; yellow or green sputum suggests a bacterial infection.

• Microscopy
  - Gram stain (Gram positive, -negative)


• Culture
  - Aerobic on blood agar plates
  
• Antibiotic Suspectibility
  
• Serology (detection of viruses)
  - Haemagglutinin Inhibition (HI)
  - Enzyme-Linked ImmunoSorbent Assay (ELISA)
  
• Others
  - Oxidase test (Oxidase-positive, -negative)
  - Catalase test (Catalase-positive, -negative)
  

References

1) http://www.merck.com/mmhe/sec04.html > Bronchitis
2) http://en.wikipedia.org/wiki/Main_Page > Moraxella_catarrhalis
3) http://en.wikipedia.org/wiki/Main_Page > Haemophilus_influenzae
4) http://en.wikipedia.org/wiki/Main_Page > Streptococcus_pneumoniae

Dorothy
TG01