respiratory infections - microbiology

this is a series of lectures on microbiology useful for undergraduate and postgraduate, medical and paramedical students

1. Dr. Ashish V. Jawarkar
Diseases of the Respiratory System

2. Dr. Ashish V. Jawarkar
The Upper Respiratory System
Consists of:
Nose
Pharynx
(throat)
Middle ear
Eustachian
tubes

3. Dr. Ashish V. Jawarkar
The Lower Respiratory System
Consists of:
Larynx
Trachea
Bronchial tubes
Alveoli
Pleura

4. Dr. Ashish V. Jawarkar
Upper Respiratory System defense
•Coarse hairs in the nose filter large
particles from air entering the respiratory
tract.
•The ciliated mucous membranes of the
nose and throat trap airborne particles and
remove them from the body.
•Lymphoid tissue, tonsils, and adenoids
provide immunity to certain infections.

5. Dr. Ashish V. Jawarkar

6. Dr. Ashish V. Jawarkar
Lower respiratory tract defense
The lower respiratory
system is usually sterile
because of the action of the
ciliary escalator.
Microorganisms hoping to
infect the respiratory tract
are caught in the sticky
mucus and moved up by the
mucociliary escalator.

7. Dr. Ashish V. Jawarkar
Upper Respiratory System Diseases
Most respiratory tract infections
are self-limiting.
Often caused by bacteria & viruses
in combination

8. Dr. Ashish V. Jawarkar
Upper Respiratory System Diseases
Pharyngitis: inflammation of the pharynx
Laryngitis: swelling and irritation (inflammation) of
the voice box (larynx)
Tonsillitis: inflammation of the tonsils
Sinusitis: inflammation of the sinuses

9. Dr. Ashish V. Jawarkar
Agents of URTi
S. pneumonia – pharyngitis/tonsillitis
S. Pyogenes – pharyngitis / tonsillitis
C. diphtheria - diptheria
B. pertussis – whooping cough
Common cold – rhino virus

10. Dr. Ashish V. Jawarkar
Streptococcal Pharyngitis
Also called strep throat
Streptococcus pyogenes /
strep. pneumoniae
Gram positive cocci
chains

11. Dr. Ashish V. Jawarkar
Corynebacterium Diphtheriae
Gram positive club shaped rod

12. Dr. Ashish V. Jawarkar

13. Dr. Ashish V. Jawarkar

14. Dr. Ashish V. Jawarkar
Diphtheria
Diphtheria membrane : Fibrin, tissue, bacterial
cells
+!$$!,-./
•Leading infectious killer of children in U.S. in 1935

15. Dr. Ashish V. Jawarkar
Diphtheria
Still common in developing countries where
immunizations aren't given routinely.
Up to 40% to 50% of those who don't get
treated can die.
The exotoxin inhibits protein synthesis, and
heart, kidney, or nerve damage may result.
Prevented by DTP vaccine

16. Dr. Ashish V. Jawarkar
Lab diagnosis
Microscopy – Gram’s , Albert’s
Culture – selective media containing tellurite,
Loeffler’s serum slope

17. Dr. Ashish V. Jawarkar
Pertussis / whooping cough
Causes whooping
cough
Mostly in children
Coughing thru
strained vocal
cords produces
sound

18. Dr. Ashish V. Jawarkar
diagnosis
Mostly clinical
Bacteria does not grow on ordinary media
Prevented by vaccination – DPT

19. Dr. Ashish V. Jawarkar
Bacteria, viruses, and fungi cause
Bronchitis – S. pneumoniae
Pneumonia – S. pneumoniae, Klebsiella,
Mycoplasma
Tuberculosis - M. tuberculosis
Lower Respiratory System Diseases

20. Dr. Ashish V. Jawarkar
Mycoplasma
Bacteria with no cell walls
Gram negative, better stained with Giemsa stain

21. Dr. Ashish V. Jawarkar
Grow on media enriched with serum
Colonies give fried egg appearance

22. Dr. Ashish V. Jawarkar
Mycoplasmal Pneumonia
Primary atypical pneumonia; walking pneumonia
No physical signs/symptoms
X ray shows lower lobe pneumonia
Genitourinary infections

23. Dr. Ashish V. Jawarkar

24. Dr. Ashish V. Jawarkar
Viral Pneumonia
Viral pneumonia occurs as a complication of
influenza, measles, or chickenpox
Viral etiology suspected if no other cause is
determined

25. Dr. Ashish V. Jawarkar
Respiratory Syncytial Virus (RSV)
The most common viral respiratory disease in
infants; 4500 deaths annually
Causes cell fusion (syncytium) in cell culture
Symptoms: Pneumonia in infants
Diagnosis: Serological test for viruses and
antibodies
Treatment: Ribavirin, palivizumab

26. Dr. Ashish V. Jawarkar
Influenza (Flu)
Symptoms: Chills, fever, headache, and muscle
aches
No intestinal symptoms
1% mortality, very young and very old
Treatment: Zanamivir and oseltamivir inhibit
neuraminidase
Prophylaxis: Multivalent vaccine (currently grown
in Embryonated egg cultures

27. Dr. Ashish V. Jawarkar
The Influenza Virus
Hemagglutinin
(HA) spikes used
for attachment to
host cells
Neuraminidase (NA)
spikes used to
release virus from
cell

28. Dr. Ashish V. Jawarkar
Fungal Infections
Fungal spores are easily
inhaled; they may germinate in the
lower respiratory tract.
The incidence of fungal diseases has
been increasing in recent years.
The mycoses can be treated with
amphotericin B.

29. Dr. Ashish V. Jawarkar