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					 Diseases

Chapters 21-26
    Microorganisms and human
             Disease
• Things to cover
  – Diseases   of Skin and Eyes
  – Diseases   of the Nervous system
  – Diseases   of the Cardiovascular & Lymphatic
    System
  – Diseases   of the Respiratory System
  – Diseases   of the Digestive System
       How I will tackle these
• Structure and function.
• Normal Microbiota
• Some of the diseases (More diseases to
  come)
  – Bacterial
  – Viral
  – Other
• You will provide more of the details
            Skin and Eyes
                Ch 21
• Physical and chemical barrier against
  microbes
• Moist areas have greater number of
  bacteria
• Epidermis contains flattened cells of keratin
  and is essentially waterproof.
• Dermis is the living part, contains follicles,
  ducts and glands that act as week point for
  bacterial invasion.
• Sebum and perspiration can inhibit growth
  of microbes.
• Same also provide nutrients to microbiota
• The body and body cavities are lined with
  epithelia cells.
• Mucous membranes secrete mucus.
What does the integument system
              do?
               Microbiota
• Divide rapidly, resistant to desiccation and
  high salt.
• Mostly gram positive cocci.
• Never completely absent.
• Propionibacterium metabolize oil
• Pityrosporum ovale are yeast that grow in
  oily secretions, cause dandruff.
  Staphylococcal Skin Infections
• Folliculitis
   – Infections of hair follicles
• Sty
   – Folliculitis of an eyelash
• Furuncle
   – Abscess; pus surrounded by inflamed tissue
• Carbuncle
   – Inflammation of tissue under the skin
 Staphylococcal Skin Infections

• Impetigo of the
  newborn
• Toxemia
• Scalded skin
  syndrome
• Toxic shock
  syndrome

                              Figure 21.4
   Streptococcal Skin Infections

• Streptococcu
  s pyogenes
• Group A
  beta-
  hemolytic
  streptococci
• M proteins

                               Figure 21.5
• Erysipelas
   Streptococcal Skin   Infections




• Impetigo




                                 Figure 21.6, 7
         Invasive Group A
      Streptococcal Infections
• Streptokinases
• Hyaluronidase
• Exotoxin A,
  superantigen
• Cellulitis
• Necrotizing
  fasciitis

                                 Figure 21.8
  Infections by Pseudomonads

• Pseudomonas aeruginosa
  – Gram-negative, aerobic rod
  – Pyocyanin produces a blue-green pus
• Pseudomonas dermatitis
• Otitis externa
• Post-burn infections
                         Warts


• Papillomaviruses
  – Treatment:
    • Removal
       – Imiquimod (stimulate interferon production)
       – Interferon
                Poxviruses
• Smallpox
  (Variola)
  – Smallpox virus
    (Orthopox virus)
  – Variola major has
    20% mortality
  – Variola minor has
    <1% mortality
• Monkeypox
  – Prevention by
    smallpox
    vaccination
                             Figure 21.9
           Measles (Rubeola)
• Measles virus
• Transmitted by
  respiratory route
• Macular rash and Koplik's
  spots
• Prevented by vaccination
• Encephalitis in 1 in 1000
  cases
• Subacute sclerosing
  panencephalitis in 1 in
  1,000,000 cases
                               Figure 21.14
         Cutaneous Mycoses
• Dermatomycoses: tineas or ringworm
• Metabolize keratin
• Trichophyton         infects hair, skin,
  nails
• Epidermophyton       infects skin and nails
• Microsporum          infects hair and skin
• Treatment
  – Oral griseofulvin
  – Topical miconazole
Cutaneous Mycoses




                    Figure 21.16
              Candidiasis

• Candida albicans (yeast)
• Candidiasis may result from suppression of
  competing bacteria by antibiotics
• Occurs in skin; mucous membranes of
  genitourinary tract and mouth
• Thrush is an infection of mucous
  membranes of mouth
• Topical treatment with miconazole or
  nystatin
Candidiasis




              Figure 21.17
                Pediculosis
• Pediculus
  humanus capitis
  (head louse)
• P. h. corporis
  (body louse)
  – Feed on blood
  – Lay eggs (nits) on
    hair
  – Treatment with
    topical
    insecticides
                              Figure 21.19
   Microbial Diseases of the Eye
• Conjunctivitis (pinkeye)
  – Haemophilus influenzae
  – Various microbes
  – Associated with unsanitary contact lenses
• Neonatal gonorrheal ophthalmia
  – Neisseria gonorrhoeae
  – Transmitted to newborn's eyes during passage
    through the birth canal
  – Prevented by treatment newborn's eyes with
    antibiotics
           Nervous System
                Ch22
• CNS is brain and spinal cord. Is encased
  and protected by bone and membranes.
• PNS are nerves outside of the Central
  nervous system. Is not protected as
  extensively and is a rout into the CNS.
• Membranes of the CNS
  – Dura mater, arachnoid and piamater
             More nervous
• Cerebrospinal fluid instead of blood
  circulates between the arachnoid and
  piamater in the subarachnoid space.
• Cerebrospinal fluid is totally separate from
  the blood and circulatory system.
• Blood brain barrier
• Entry to CNS by bacteria is through
  peripheral nerves, though blood and
  lymphatic system.
• Meningitis is an infection of the meninges
• Encephalitis is an infection of the brain.
What does the Nervous system
            do?
Normal Microbiota?
           Bacterial Meningitis


•   Fever, headache, stiff neck
•   Followed by nausea and vomiting
•   May progress to convulsions and coma
•   Diagnosis by Gram stain of CSF
•   Treated with cephalosporins
Bacterial Meningitis




                       Table 22.1
                 Tetanus

• Clostridium tetani
• Gram-positive, endospore-forming, obligate
  anaerobe
• Grows in deep wounds
• Tetanospasmin released from dead cells
  blocks relaxation pathway in muscles
• Prevention by vaccination with tetanus
  toxoid (DTP) and booster (dT)
• Treatment with tetanus immune globulin
                  Botulism
• Clostridium botulinum
• Gram-positive, endospore-forming, obligate
  anaerobe
• Intoxication due to ingesting botulinal toxin
• Botulinal toxin blocks release of
  neurotransmitter causing flaccid paralysis
• Prevention:
  – Proper canning
  – Nitrites prevent endospore germination in
    sausages
                Botulism


• Treatment: supportive care and antitoxin
• Infant botulism results from C. botulinum
  growing in intestines
• Wound botulism results from growth of C.
  botulinum in wounds.
     Transmissible Spongiform
        Encephalopathies
• Caused by prions
  – Sheep scrapie
  – Creutzfeldt-Jakob disease
  – Kuru
  – Bovine spongiform encephalopathy
• Transmitted by ingestion or transplant or
  inherited
• Chronic, fatal
Transmissible Spongiform
   Encephalopathies




                           Figure 22.17a
   Cardiovascular and Lymphatic
          Systems Ch 23
• Consists of heart, blood and blood vessels
• Lymph, lymph vessels, lymph nodes and
  lymphoid organs.
        Body Fluids and Flow
• Heart circulates substances to and from
  tissue cells.
• Blood is a mixture of plasma and cells.
• Most substances are dissolved in plasma
• RBC’s carry oxygen.
• WBC’s are involved in defense.
• Interstitial fluid is essentially plasma and
  exits from capillaries
        Normal Microbiota?
• Life Loads?
      Sepsis and Septic Shock
• Sepsis
  – Bacteria
    growing in the
    blood
• Severe sepsis
  – Decrease in
    blood pressure
• Septic shock
  – Low blood
    pressure
    cannot be
    controlled                  Figure 23.3
                       Sepsis
• Gram-negative Sepsis
  – Endotoxins caused blood pressure decrease
  – Antibiotics can worsen condition by killing
    bacteria
• Gram-Positive Sepsis
  – Nosocomial infections
    •   Staphylococcus aureus
    •   Streptococcus pyogenes
    •   Group B streptococcus
    •   Enterococcus faecium and E. faecalis
        Viral Hemorrhagic Fevers
Classic
Yellow fever        Flavivirus   Aedes aegypti Monkeys
Dengue & DHF        Flavivirus   •   A. aegypti   No known
                                 •   A.           reservoir
                                     albopictus
Emerging
Marbug              Filovirus    •   Monkeys
                                     (?)
Ebola               Filovirus    •   Monkeys
                                     (?)
Lassa fever         Arenavirus   •   Rodents
Argentine           Arenavirus   •   Rodents
hemorrhagic fever
Bolivian            Arenavirus   •   Rodents
                 Malaria
• Plasmodium vivax, P. ovale, P malariae, P.
  falciparum
• Anopheles mosquito




                                           12.31b
    Respiratory System Ch 24
• Most common type of infection
• Usually first on way to infection.
Microbial Diseases of
the Upper Respiratory
       System
• Laryngitis: S. pneumoniae, S. pyogenes,
  viruses
• Tonsillitis: S. pneumoniae, S. pyogenes,
  viruses
• Sinusitis: Bacteria
• Epiglottitis: H. influenzae
• Upper respiratory: nose, pharynx, middle
  ear and auditory tubes.
• Filtration by coarse hairs
• Ciliated mucous membranes of nose and
  throat trap airborne particles (greater than
  10um)
• Associated with lymphoid tissues (tonsils,
  and adenoids)
    Lower respiratory system
• Larynx, trachea, bronchial tubes and
  alveoli.
• Ciliary escalator prevents microbes from
  reaching the lungs.
• Alveolar macrophage protect lungs.
• Respiratory mucus contains IgA antibodies
     Microbial Diseases of the
     Lower Respiratory System
• Bacteria, viruses, & fungi cause:
  – Bronchitis
  – Bronchiolitis
  – Pneumonia
What do the lungs do?
          Normal Microbiota
• Of throat and nasal cavity can include
  pathogens.
• Lower respiratory system is usually sterile
  because of ciliary escalator.
   Opportunistic fungi involved in
        respiratory disease:
• Aspergillus
• Rhizopus
• Mucor




                   M ucor rouxii
                                   Figure 12.2b, 12.4
     Digestive System Ch 25
• Second most common illnesses
• Usually ingestion of microbes and toxins.
• Fecal-oral transmission is broken by
  proper disposal of sewage, disinfection of
  drinking water and proper food prep and
  storage.
         Structure Function
• GI or alimentary canal: mouth, pharynx,
  esophagus, stomach, small intestine and
  large intesting, colon, anus.
• Accessory organs: teeth, tongue, salivary
  glands, liver, gallbladder and pancrease.
• Charged with ingestion, digestion,
  absorption and elimination.
         Normal microbiota
• Lots and unknown number occupy the
  mouth.
• Streptococcus mutans in mouth produces
  acid.
• Dextran from bacteria is plaque
• Bacteria number are reduced in stomach.
• Normal flora in lower gut.
           Normal Microbiota

• >300 species in mouth
• Large numbers in large intestine, including:
  – Bacteroides
  – E. coli
  – Enterobacter
  – Klebsiella
  – Lactobacillus
  – Proteus
What does the gut do?
   Bacterial Diseases of the Lower
          Digestive System
• Symptoms usually include diarrhea,
  gastroenteritis, dysentery
• Treated with fluid and electrolyte
  replacement
• Infection caused by growth of pathogen
  – Incubation from 12 hr to 2 wk
• Intoxication caused by ingestion of toxin
  – Symptoms appear 1-48 hr after ingestion
Urinary and Reproductive systems
• Regulates chemical components of blood
  excretes nitrogenous waste.
• Infections can be from outside source or
  form normal microfloura.
• Microbes can use a system to transfer
  gametes to also transfer themselves.
Microbial Diseases of
   the Urinary and
Reproductive Systems
• Microbes usually enter the urinary
  system through the urethra
• Microbes usually enter the
  reproductive system through the:
  – Vagina (females) or urethra (males)
Function?
          Normal Microbiota


• Urinary bladder and upper urinary tract
  sterile
• Lactobacilli predominant in the vagina
• >1,000 bacteria/ml or 100 coliforms/ml of
  urine indicates infection
   Sexually Transmitted Diseases
              (STDs )


• Prevented by condoms
• Treated with antibiotics
               Websites.
• STD’s
  http://hab.hrsa.gov/publications/hrsawome
  n/colorplates/colorplates.htm

				
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