1. Normal Microbial Flora and Immunity of Respiratory Tract
Dr Nazia khan

2. objectives
Describe innate immune defense mechanisms of respiratory tract.
Identify Normal Microbial Flora of upper respiratory tract.
Discuss Beneficial Role & disease causing ability of Normal Flora of respiratory tract.

4. Respiratory tract is divided into upper and lower respiratory tract:
It is one of the most important portal of entry for microbes

5. IMMUNITY Functions of immune system
BODY’S ABILITY TO RESIST OR ELIMINATE POTENTIALLY HARMFUL FOREIGN MATERIALS OR ABNORMAL CELLS.
Functions of immune system
Defending against invading pathogens.
Removing worn out cells & damaged tissues, paving the way for wound healing & repair.
Identifying & destroying abnormal/mutant cells (Immune surveillance)---- defense against cancer
Mounting inappropriate immune responses which lead either to allergies or autoimmune diseases.

8. INNATE IMMUNE DEFENSE MECHANISMS OF RESPIRATORY TRACT
Characteristics of innate immunity
Resistance that exists prior to exposure
Readily available
Non specific
Does not improve on repeated exposures
There is no immunologic memory

9. ANATOMICAL BARRIERS: B. PHYSIOLOGICAL BARRIERS:
. ARCHITECTURE OF THE NOSE:
NASAL HAIR: Filter out dust & other large airborne particles
nasal meatus
STICKY MUCUS: ACTS AS TRAPPING MECHANISM
CILIARY MOTION -dislodge pathogens
B. PHYSIOLOGICAL BARRIERS:
Cough Reflex: aids IN EXPECTORATING sputum
Sneeze Reflex: Helps expels irritant out from URT
Mucociliary Escalator:
Constant movement of mucus from LRT towards pharynx
Extremely important mechanism
Damage to this causes many infective diseases of LRT

10. BIOCHEMICAL & CELLULAR COMPONENTS
UPPER RESP TRACT
Nasal fluid contains
Lysozyme
Lactoferrin
IgA antibodies
LOWER RESP TRACT
No cilia
Alveolar fluid
IgG antibodies
Alveolar macrophages (phagocytosis)
Neutrophils
Inflammatory response

11. MICROBIOLOGICAL
Alpha hemolytic streptococci: appear within 12 hours after birth ,become dominant organisms of the oropharynx
micrococci, coliforms, proteus, lactobacilli
Predominant organisms in the upper respiratory tract : nonhemolytic and alpha hemolytic streptococci, Neisseria
Others: staphylococci, diphtheroids, haemophili, pneumococci, mycoplasmas, prevotella

12. BENEFICIAL ROLE OF normal flora
Inhibits attachment of pathogens
Covers the receptor sites
Physical competition for nutrients
Create adverse environment for pathogen by
Mutual inhibition by metabolic or toxic products
Mutual inhibition by antibiotic materials or bacteriocins
Other mechanisms
Respiratory epithelium

13. HARMFUL EFFECTS OF RESPIRATORY FLORA
ENDOGENOUS INFECTIONS
URT infections by viruses, smoking etc.-ciliary damage
Acute bacterial meningitis (Ns. Meningitidis)
Acute lobar pneumonia (Streptococcus pneumoniae)
Extension of resp flora to sinuses –Acute sinusitis
Nasal packing in epistaxis-Infective endocarditis (Viridans Streptococci)
Use of antimicrobials
Thrush (Candida)
Immune suppression results in overgrowth of flora
Acute esophagitis (Candida ) in HIV

14. HARMFUL EFFECTS OF RESPIRATORY FLORA
EXOGENOUS INFECTION/ NOSOCOMIAL INFECTIONS
Surg site infection in hosp by Staph aureus
Usually source is healthcare provider
MRSA outbreaks in ITCs/ wards from poor hand hygiene
Thrush
HIV Esophagitis

15. Thank you