Respiratory Tract Pathogens

Respiratory tract is a continuum

Upper respiratory tract defenses
Mucociliary system
Flushing action of saliva

Infections
Restricted to surface epithelium
Spread to other organs

Upper Respiratory Tract Infections

Infection of the nasopharynx
Common cold
Viruses
Rhinoviruses
Coronaviruses

Transmitted via aerosols, contaminated hands

Pathology - damage to epithelial cells
Secretion of fluid with cytokines

Other causes of colds
Coxsackie virus
Influenza virus
Parainfluenza virus
Respiratory syncytial virus
Adenovirus
Echoviruses

Treatment - symptomatic

Pharyngitis and Tonsillitis

Pharyngitis results from infection of the overlaying mucosa or from inflammatory and immune responses in the lymphoid tissues.

70% viral in origin
Adenovirus - pharyngoconjunctivitis
EBV
HSV
Coxsakie A virus
Rhinovirus, coronavirus
Parainfluenza, influenza viruses

Bacterial infections
Strep. Pyogenes
Corynebacterium diphtheriae
Haemophilus influenzae
Borrelia vincenti
Neisseria gonorrhoeae

Diagnosis - clinically, throat swabs

Otitis and sinusitis

Mumps, RSV
Strep. Pneumoniae, H. influenzae

Laryngitis and tracheitis

Usually parainfluenza virus
Occasionally influenza virus, RSV
C. diptheriae

Lower Respiratory Tract Infections
Infections tend to be more severe than those of the upper respiratory tract.

Syndromes
Acute bronchitis
Acute exacerbations of chronic bronchitis
Acute bronchiolitis
Pneumonia

Acute bronchitis - inflammation of the tracheobronchial tree

Viruses
Influenza virus
Adenovirus

Bacteria
Mycoplasma pneumoniae

Presentation: cough, treatment is usually symptomatic

Acute exacerbations of chronic bronchitis

Viruses
Bacteria
Strep. pneumoniae
H. influenzae

Bronchiolitis - children, especially 2 years old or younger

75% - Respiratory syncytial virus

epithelial cell necrosis, inflammatory infiltrate

Pneumonia
Lobar pneumonia
Bronchopneumonia
Interstitial pneumonia
Lung abscess

Age - derminant of causative agent

Childhood pneumonia - usually viral or bacterial secondary to a viral infection
Influenza, parainfluenza,
respiratory syncytial virus

Pneumonia

Adults - bacterial causes are more common

Bacteria
Strep. pneumoniae 25-60% of cases
H. influenzae
Atypical pneumonia -
M. pneumoniae
Chlamydia pneumoniae
Legionella pneumophila
Coxiella burnetii


Viruses
Influenza
Parainfluenza
Measles - secondary bacterial pneumonia
Respiratory syncytial virus
Adenovirus
Cytomegalovirus

Symptoms - chest pain, shortness of breath, cough, difficulty breathing

Treatment - depends on organism

Diagnosis

Bacterial culture - sputum specimen
Throat swab

Atypical bacteria infections - serological tests

Viruses
Culture
Antigen detection
Antibody detection

Lab February 21, 22

You will receive a case vignette describing a patient. Your goal is to diagnose the patient's problem by requesting additional information and/or by performing serological diagnostic tests in the laboratory.

· Organize into groups of 4-5 students
· Sign up for a case number on the door of Gros. 128 by Friday, 2/8

Go the web page http://oak.cats.ohiou.edu/~biegalke/classes.html
Obtain the case that corresponds to the number of the case that your group signed up for.

Read through the case and decide:
§ What additional information you would like
§ What laboratory tests you would like to run. The tests that will be available in the lab are:
· Mycoplasma
· RSV
· Group A strep
· Influenza
· Anti-streptolysin O

(Note: Not all of the cases can be definitively diagnosed with the tests that will be available in the lab.)

Email me (biegalke@ohiou.edu) with your requests.

Perform diagnostic tests in the lab, understanding the basis behind the diagnostic tests. Turn in a diagnosis sheet with your name, case number, diagnosis, what laboratory tests you performed and what the test measured. Fill out and turn in lab sheet from your course packet.