Microorganisms and Disease

1
Microorganisms and Disease

• How does the human body and various
  microorganisms interact in terms of disease?

2
Infectious Disease

• skin, mucous membranes, antibodies
• bacteria can produce capsules, enzymes, and
  toxins
• infectious disease is the primary cause of death
  world-wide
• 1918-1919 influenza pandemic killed more than
  20 million people world-wide and 500,000 people
  in the United States

3

• Readings question 1
• Describe the chain of infection.

4
Infection vs. Disease

• Infection the entry, establishment and
  multiplication of pathogenic organisms within a
  host
• Disease an abnormal state in which part or all
  of the body is not properly adjusted or is
  incapable of performing normal functions any
  change from a state of health

5
Factors that Influence the Occurrence of Disease

• 1) virulence of the organisms
• 2) portal of entry of the pathogen
• 3) number of organisms present
• 4) the resistance of the host

6
Virulence of Organisms

• virulence relative power of an organism to
  produce disease
• resistance
• host
• pathogen
• contamination the act of introducing disease
  germs or infectious material into an area or
  substance

7
Virulence (contd)

• true pathogen an organism that due to its
  virulence is able to produce disease
• attenuation dilution or weakening of virulence
  of a microorganism, reducing or abolishing
  pathogenicity
• pathogenicity the state of producing or being
  able to produce pathological changes and disease

8
Virulence (contd)

• indigenous flora synonymous with normal flora,
  indicates the microbial population that lives
  with the host in a healthy condition
• opportunists an organism that exists as part
  of the normal flora but may become pathogenic
  under certain conditions
• drug-fast resistant, as in bacteria, to the
  action of a drug or drugs

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MRSA

• Methicillin-resistant Staphylococcus aureus

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MRSA

• 2005 94, 360 people 18,650 died (CDC)
• 85- healthcare 66 outside of hospital
• colonized but not infected
• invasive medical procedures, weakened immune
  systems
• sepsis, surgical site infections, pneumonia

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MRSA (contd)

• mode human hands
• staph generally harmless unless they enter
  through a cut or wound
• 1990 CA-MRSA (community-associated)
• preventable

12
Types of Infections and Diseases

• exogenous infections originating outside an
  organ or part
• endogenous infections produced or arising from
  within a cell or organism
• acute diseases symptoms develop rapidly but may
  only last for a short period of time
• chronic diseases develop slowly and are likely
  to continue or recur for long periods of time

13
Infections and Diseases (contd)

• communicable diseases a disease that may be
  transmitted directly or indirectly from one
  individual to another
• endemic disease that occurs continuously in a
  particular region, but has low mortality
• epidemic appearance of an infectious disease
  or condition that attacks many people at the same
  time in the same geographical area

14
Infections and Disease (contd)

• pandemic a disease affecting the majority of
  the population of a large region or one that is
  epidemic at the same time in many different parts
  of the world
• sporadic a disease which occurs occasionally
  or in scattered instances
• noncommunicable diseases do not spread from one
  host to another

15

• Readings question 2
• Define local, focal, and general infections, and
  give an example of each.

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Infections (contd)

• primary the first infection that a host has
  after a period of health
• secondary infection caused by a different
  organism than the one causing the primary
  infection
• mixed infection caused by two or more
  organisms
• blood viremia bacteremia

17

• Readings question 3
• Define septicemia and toxemia and include an
  example of each. What are the symptoms/characteri
  stics for septicemia and toxemia?

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Factors Influencing Virulence

• Readings question 4
• Describe toxins, exotoxins, and endotoxins, and
  give an example of each.
• Capsules and Endospores

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Sources of Infection

• Human Reservoirs carriers
• Universal Precautions
• Animal Reservoirs zoonoses
• Environmental Reservoirs Vibrio cholera
• Salmonella typhi

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Transmission of Infections

• Direct viral respiratory disease, staphylococcal
  infections, hepatitis A, measles, scarlet fever,
  STDs, AIDS, infectious mononucleosis
• - hand washing, gloves etc.
• Indirect
• Readings question 5 Describe the primary
  mechanisms of indirect contact. Include examples
  with each mechanism.
• What are fomites?

21
Portal of Entry

• 5 portals of entry
• 1) skin and mucous membranes
• 2) respiratory tract
• 3) digestive tract
• 4) genito-urinary tract
• 5) placenta

22
Skin and Mucous Membranes

• membranes line the respiratory tract,
  gastrointestinal tract, genitourinary tract, and
  conjunctiva
• skin is one of the largest organs of the body
• - hair follicles and sweat gland ducts
• parenteral route microorganisms are deposited
  directly into the tissues

23
Respiratory Tract

• easiest and most frequently traveled portal of
  entry
• airborne pathogens
• sneezing, coughing, touching contaminated
  surfaces and then touching the mouth or nose,
  dust particles
• pathogenic bacterial spores may be inhaled

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Digestive Tract

• Food, water, contaminated fingers
• HCl and enzymes in the stomach
• bile and enzymes in the small intestine
• poliomyelitis, hepatitis A, typhoid fever,
  amoebic dysentery, giardiasis, shigellosis,
  cholera

25
Genitourinary Tract

• pathogens that are contracted sexually
• genital warts, chlamydia, herpes

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Placenta

• CMV cytomegalovirus
• 10 infants premature delivery, jaundice,
  enlarged liver and spleen, microcephaly,
  seizures, rash, feeding difficulties
• hearing, vision, neurologic, and developmental
  problems
• no vaccine
• hand washing, not sharing eating utensils, avoid
  kissing or intimate contact with CMV

27
Portals of Exit

• secretions, excretions, discharges, shed tissue
• related to the infected part of the body
• microbe generally uses the same portal for entry
  and exit
• respiratory TB, whooping cough, pheumonia,
  scarlet fever, meningococcal meningitis,
  chickenpox, measles, mumps, small pox, influenza

28
Portals of Exit (contd)

• gastrointestinal feces- salmonellosis, cholera,
  typhoid fever, shigellosis, amoebic dysentery,
  poliomyelitis
• saliva - rabies, mumps, infectious mononucleosis
• genitourinary secretions from penis and vagina-
  STDs
• urine- tyhphoid fever brucellosis

29
Portals of Exit (contd)

• skin or wound infections - impetigo, skin
  ringworm, herpes simplex, warts
• Infected blood insects, contaminated needles
  and syringes
• insects yellow fever, plague, tularemia,
  malaria
• con. needles syringes AIDS, hepatitis B

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Number of Organisms Present

• Third factor

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Resistance of the Host

• mechanical defenses
• physiological defenses
• chemical defenses

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Mechanical Defenses

• Skin epithelium (epidermis), sebaceous glands,
  dryness, necrobiosis
• Eyes lacrimal apparatus
• Saliva cleansing action
• Respiratory Tract mucus, ciliated epithelium
• Urinary Tract flushing action

33
Physiological Defenses

• Inflammation pus
• Fever 102-104 degrees
• Phagocytosis phagocyte ingests material

34
Chemical Defenses

• Lysozome enzyme that breaks down cell walls of
  gram-positive bacteria and some gram-negative
  bacteria
• Sebum sebaceous glands, oily substance,
  protective film, lowers skin pH
• Gastric Juice HCl, enzymes, mucus, acidic
• Interferon eukaryotic cells, surface receptors

35
Immunology

• Latin immunis to exempt
• Why is it that some people tend to be sick more
  often than others?
• Why can two people eat the same infected chicken,
  and only one person contracts food poisening?
• children, elderly, immunocompromised

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Antigens

• a foreign substance that stimulates the
  formation of antibodies that react specifically
  with it
• substance that provoke a specific response
• Antibodies glycoprotein substance developed by
  the body in response to, and interacting
  specifically, with an antigen. Also known as
  immunoglobulin.

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Antigen-Antibody Reactions

• 1) destroy pathogens by neutralizing the toxins
  the pathogen produces
• 2) coat the pathogen with a substance that
  attracts phagocytes by forming a substance that
  clumps the antigens together
• 3) prevent the pathogen from adhering to the
  bodys cells

38
Types of Immunity

• Natural (Innate)
• Acquired Naturally Acquired active, passive
• Artificially Acquired
• - active vaccines - passive
  antibodies
• immune serums

39
Hypersensitivity(Allergy)

• an acquired, abnormal immune response to a
  substance (allergen) that does not normally cause
  a reaction
• Immediate 2 30 minutes
• systemic (shock, breathing difficulties)
• Localized (hay fever, asthma, hives)
• Delayed 1-2 days
• TB skin test, contact dermatitis

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Bacterial Diseases

• Staphylococcus
• Streptococcus

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Pathogenicity

• the state of producing or being able to produce
  pathological changes and disease

42
Staphylococcus

• a genus of gram-negative, nonmotile,
  opportunistic bacteria which tend to aggregate in
  irregular, grape-like clusters

43
Readings Question 1

• Staphylococcus aureus is the most pathogenic of
  the staphylococci. What are its toxins capable
  of doing? What enzymes does it produce, and what
  is their known effect?

44
Staphylococcal Food Poisoning

• caused by ingesting an enterotoxin
• high resistance to heat, drying and radiation,
  and high osmotic pressures
• inhabitant of nasal passagescontaminates the
  hands..readily enters food
• mechanical vectors
• mayonnaise, cream sauces

45
Skin and Wound Infections

• Sty infected follicle of an eyelash

46
Skin and Wound Infections (contd)

• Pimple infected hair follicle
• Abscess more serious hair follicle infection
• furuncle/boil superficial
• carbuncle deeper
• Risk of underlying tissues becoming infected
• Toxemia toxins circulate

47
Scalded Skin Syndrome
48
Toxic Shock Syndrome

• S. aureus growth associated with the use of a new
  type of highly absorbent vaginal tampon
• swell with menstrual fluids and adhere to the
  vagina
• tears in the vaginal wall

49
Streptococcus

• spherical shaped bacteria occurring in chains
• What are the implications for the embalmer when
  dealing with saprophytes?

50
Streptococcus pneumoniae( pneumococcus)

• gram-positive ovoid bacterium
• cell pairs surrounded by capsule
• common cause of
• 1) lobar pneumonia
• 2) meningitis
• 3) otitis media

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Lobar Pneumonia

• Readings question 2
• What is lobar pneumonia, and how is it
  characterized?
• What are some of the predisposing conditions for
  this disease?
• penicillin and fluoroquinolones

52
Meningitis

• 70 of the population are healthy carriers
• Gram-positive encapsulated diplococcus
• Leading cause of bacterial meningitis
• Most cases between 1 month and 4 years
• Broad-spectrum cephalosporins
• CSF obtained by a spinal tap
• Vaccine Pneumococcal Conjugated Vaccine

53
Otitis Media

• 85 before 3 years of age (Eustachian Tubes)

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Streptococcus pyogenes

• Scarlet Fever streptococcal pharyngitis
• Septic Sore Throat respiratory secretions
• penicillin
• Puerperal Sepsis Childbirth/Childbed Fever
• Rheumatic Fever arthritis and fever
• 50 inflammation of the heart
• penicillin
• Syndenhams chorea