Ch09 infectious disease and immunology (1)

Fundamental
 Microbiology
 

CHAPTER 9
Introduction to Infectious disease
and Immunology


Normal Microbiota and the Host
•  Loca&ons
 of
 normal
 
microbiota
 on
 and
 in
 
the
 human
 body
 
-­‐
 Skin
 and
 mucous
 
-­‐
 Gastrointes&nal
 tract

 
-­‐
 Urogenital
 tract
 
 
• Microbes
  that
  engage
  in
 
m u t u a l
  o r
  c o m m e n s a l
 
a s s o c i a & o n s
  –
  n o r m a l
 
(resident)
  flora,
  indigenous
 
flora,
 microbiota
 

 

Includes
 
bacteria,
 fungi,
 
 
protozoa
 and
 
 
arthropods
 

 


Normal Microbiota and the Host
•  Normal
 microbiota
 permanently
 colonize
 the
 
host
 
•  Symbiosis
 is
 the
 rela&onship
 between

 normal
 
microbiota
 and
 the
 host
 



Normal Microbiota and the Host
•  In
 commensalism
 (Hội
 sinh),
 one
 organism
 is
 
benefited
 and
 the
 other
 is
 unaffected.
 
•  In
 mutualism
 (hỗ
 sinh),

 both
 organisms
 benefit.
 
Exp.
 Rumen
 microbiota
 
•  In
 parasi  one
 organism
 is
 benefited
 at
 the
 
expense
 of
 the
 other.
 
Exp.
 Enterobacteria
 
•  Some
 normal
 microbiota
 are
 opportunis

 
pathogens
 
Exp.
 E.
 coli
 
 


What is a role of normal microbiota?
•  Normal
 microbiota
 protect
 the
 host
 by:
 
 
–  occupying
 niches
 that
 pathogens
 might
 occupy
 
–  producing
 acids
 (lac&c
 acid

 bacteria
 in
 vagina
 
 
–  producing
 bacteriocins
 


Principles of Disease and
Epidemiology
•  Pathology
 
 Study
 of
 disease
 
•  Pathogenesis
 Development
 of
 disease
 
•  Infec&on
 
 
 
 
 
 

 Coloniza&on
 of
 the
 body
 by
 
 
 
 
 

 
 
 
 
 
 pathogens
 
•  Disease
 
 
 
 
 
 
 An
 abnormal
 state
 in
 which

 the
 
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 body
 is
 not
 func&onally
 normally
 


Infectious diseases
•  Infec

  a
  condi&on
  in
  which
  pathogenic
 
microbes
 penetrate
 host
 defenses,
 enter
 &ssues
 
and
 mul&ply
 
•  Disease
 –
 An
 abnormal
 state
 in
 which
 the
 body
 
is
 not
 func&onally
 normally

 
•  Caused
  by
  microbes
  or
  their
  products
  –
 
infec  disease
 


Reservoirs of Infection
•  Reservoirs
 of
 infec&on
 are
 con&nual
 sources
 of
 infec&on.
 
•  Human
 —
 AIDS,
 gonorrhea
 
•  Carriers

 may
 have
 inapparent
 infec&ons
 or
 latent
 
diseases
 
•  Animal
 —
 Rabies,
 Lyme
 disease
 
•  Some
 zoonoses
 may
 be
 transmiTed
 to
 humans
 
•  Nonliving
 —
 Botulism,
 tetanus
 
•  Soil
 

Koch's Postulates


Transmission of Disease

Contact
 
 
Direct
 

 
 
Indirect
Droplet


 Requires
 close
 associa&on
 between
 
 

 
 infected
 
 

 and
 
 
 suscep&ble
 host
 

 Spread
 by
 fomites
 

 Transmission
 via
 airborne
 droplets
 


Transmission of Disease


Transmission of Disease
•  Vehicle
 

 

 

 Transmission
 by
 an
 inanimate
 reservoir
 

 (food,
 water)
 

•  Vectors
 

 

 


 Arthropods,
 especially
 fleas,
 &cks,
 and
 

 mosquitoes
 

•  Mechanical


 Arthropod
 carries
 pathogen
 on
 feet
 
 

•  Biological
 


 Pathogen
 reproduces
 in
 vector
 


Emerging Infectious Diseases
1
 

2
 
1+2
 

Living
 condi&ons
 

Host
 state
 
1+2+3
 
disease
 
1+3
 

2+3
 

Pathogenic
 microorganism’s
 
 
source
 

3
 
Disease
 triangle
 

Mechanisms of Pathogenicity



Portals of Entry
How
 microorganisms
 enter
 a
 host?
 
•  Mucous
 membranes
 
–  Respiratory
 tract
 
–  Gastrointes&nal
 tract
 
–  Genitourinary
 tract
 
–  Conjunc&va
 

•  Skin
 

–  Tough
 so
 rare
 -­‐
 Necator
 americanus
 -­‐
 hookworm
 

•  Parenteral
 route
 
–  Puncture,
 injec&on,
 bites,
 cuts,
 wounds,
 surgery,
 etc
 


1st Portal of Entry: Mucous Membranes -Respiratory

•  Respiratory
 Tract
 
–  microbes
 inhaled

 
into
 mouth
 or
 nose
 
in
 droplets
 of
 
moisture
 or
 dust
 
par9cles
 
–  Easiest
 and
 most
 
frequently
 traveled
 
portal
 of
 entry
 

• 

Common cold

• 

Flu

• 

Tuberculosis

• 

Whooping cough

• 

Pneumonia

• 

Measles

• 

Strep Throat

• 

Diphtheria

Mucous
 membranes:
 G.I.
 Tract
 
•  Salmonellosis
 (ngộ
 đọc
 
thực
 phẩm)
 
–  Salmonella
 sp.
 
•  Shigellosis
 (lỵ)
 
–  Shigella
 sp.
 
•  Cholera
 
–  Vibrio
 cholorea
 
Fecal - Oral Diseases
•  Ulcers
 (loét

 dạ
 dày)
 
•  These pathogens enter the G.I. Tract at
–  Helicobacter
 pylori
 
one end and exit at the other end.
•  Botulism
 
•  Spread by contaminated hands & fingers
–  Clostridium
 botulinum
  or contaminated food & water
•  Poor personal hygiene.


Mucous Membranes of the Genitourinary System
Gonorrhea
Neisseria gonorrhoeae
Syphilis (giang mai)
Treponema pallidum
Chlamydia
Chlamydia trachomatis
HIV
Herpes Simplex II
 


Mucous

 Membranes:
 Conjunc&va
 
•  Conjunc  
 
– 
 mucous
 membranes
 that
 cover
 the
 
eyeball
 and
 lines
 the
 eyelid
 


 

 


 
 
 
 

 
 
 Trachoma
 -­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐
à
 
–  Chlamydia
 trachoma9s
 


2nd Portal of Entry: Skin
•  Skin
 -­‐
 the
 largest
 organ
 of
 the
 body.
 When
 
unbroken
 is
 an
 effec&ve
 barrier
 for
 most
 

microorganisms.
 

 
•  Some
 microbes
 can
 gain
 entrance
 thru
 
openings
 in
 the
 skin:
 hair
 follicles
 and
 sweat
 
glands
 


3rd Portal of Entry: Parenteral
Microorganisms
 are
 deposited
 into
 the

 &ssues
 below
 
the
 skin
 or
 mucous
 membranes
 
– Punctures
 
– injec&ons
 
– bites
 
– scratches
 
– surgery
 
– spligng
 of
 skin
 due
 to
 swelling
 or
 dryness
 

Preferred Portal of Entry
~
 Just
 because
 a
 pathogen
 enters
 your
 body
 it
 does
 not
 mean
 it’s
 going
 to
 
cause
 disease~
 

• 
 Pathogens
 -­‐
 preferred
 portal
 of
 entry
 
–  Small

 pox
 via
 variola&on
 
–  Streptococcus
 pneumoniae
 
 
 
•  if
 inhaled
 can
 cause
 pneumonia
 
•  if
 enters
 the
 G.I.
 Tract,
 no
 disease
 

–  Salmonella
 typhi
 
 
 
•  if

 enters
 the
 G.I.
 Tract
 can
 cause
 Typhoid
 Fever
 (Thương
 
hàn)
 
•  if
 on
 skin,
 no
 disease