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10
Microbiology
2
Important People in Microbiology
• Anton Van Leeuwenhoek– Magnifying glass
• Saw microorganisms from teeth for the first time
• Ferdinand Julius Cohn– Classified bacteria as plants– Divided bacteria into four groups
3
Important People in Microbiology
• Louis Pasteur– Process of fermentation
• Proved bacteria causes disease
4
Important People in Microbiology• Robert Koch
– Koch postulated that organisms must be: • Present in all cases of the disease• Isolated in pure culture• Capable of producing the disease in another
person or animal• Recovered again in pure culture
5
Important People in Microbiology
• Richard Julius Petri– Petri dish– Further developed technique for
dispensing the bacteria onto the medium
6
Groups of Microorganisms• Bacteria and virus groups
– Gram stain used to differentiate• Gram positive if they keep their dark purple color• Gram negative if they lose the color
7
Bacteria• Need for oxygen
– Aerobic bacteria must have oxygen to grow and live
– Anaerobic bacteria are destroyed in the presence of oxygen
– Facultative anaerobic bacteria grow with or without oxygen present
8
Diseases Caused by Bacteria
• Tuberculosis– Bacteria found in lungs– Fatigue, fever, weight loss, persistent cough– Airborne
• Dental personnel must wear masks
– Detected by a skin test and/or chest x-ray– Treatment is antibiotics or other drugs
9
Diseases Caused by Bacteria
• Diphtheria– Severe throat infection and fever
• Pertussis– Respiratory disease – Mainly affects infants and young children
• Tetanus– Stiffness of the jaw (“lockjaw”)
10
Diseases Caused by Bacteria
• Strep throat– Very common– Sore throat, fever, general malaise– Streptococcus mutans
• Species of the same bacteria• Implicated in dental caries and endocarditis
11
Diseases Caused by Bacteria
• Staphylococcal infections– Bacteria groups grow in clusters
• Antibiotics are the first line of treatments
12
Diseases Caused by Bacteria• Anthrax
– Humans can get disease through cuts in skin or eating diseased meat
– Powder form • Symptoms within 1 to 6 days• Fever, weakness, dry hacking cough• Prevention by vaccination or antibiotic
treatment before symptoms
13
Diseases Caused by Bacteria• Chlamydiae
– Microorganisms somewhere between bacteria and viruses (small in size)
• Genital, eye, and lymph node infections• Most common sexually transmitted disease in
the United States• Antibiotics used as treatment
14
Protozoa
• Just below visibility of the naked eye
• Always dividing and changing shape
• Flagella– Many have this long, threadlike appendage
15
Diseases Caused by Protozoa
• Amebic dysentery– Severe diarrhea
• Abscesses may develop in liver
– Prevalent in countries where drinking water is contaminated and poor hygiene conditions prevail
16
Diseases Caused by Protozoa
• Periodontal disease (protozoa and bacteria)– Both found in inflamed tissue around the tooth– Protozoa is found in the plaque in the periodontal
pockets around the tooth– Treatments include removal, cleaning of plaque
and tissue, and oral hygiene maintenance
17
Diseases Caused by Protozoa
• Malaria– Symptoms during the first two weeks
• Fever and soreness at point of entry
18
Rickettsiae
• Parasites cannot live outside a host– Lice, fleas, ticks, and mites transmit
disease to humans
19
Diseases Caused by Rickettsiae
• Head lice– Common among children in schools– Transmitted easily through direct contact– Eggs reproduce in hair shafts– Treatment
• Medicated shampoo and cleaning bedding, brushes, and clothing with very hot water
20
Diseases Caused by Rickettsiae
• Rocky Mountain Spotted Fever – Rare, curable– Small pink dots appear
• Typhus– Rare, treatable– Severe headache, back and limb pain,
constipation, rash, and confusion
21
Yeasts and Molds
• Includes bread yeast, mushrooms, and bread molds
• Cannot be killed by bacterial antibiotics – Made from mold but does not act on it
22
Diseases Caused by Yeasts and Molds
• Candidiasis– Covered by mucus in areas such as the inside
of the mouth or the vaginal area– Treated by antibiotics
23
Diseases Caused by Yeasts and Molds
• Tinea – Appearance named according to site
infected• Tinea pedis (Athlete’s foot)• Tinea corporis (Ringworm)• Tinea unguium
– White patches on toe or fingernail
24
Diseases Caused by Yeasts and Molds
• Prion (pree-on) – Proteinaceous infectious particles made of
only protein• Mad Cow Disease• Creutzfeldt-Jacob Disease
25
Viruses
• Must live inside hosts
• Antibiotics cannot kill the virus
• Treatment is primarily to ease the symptoms for the patient’s comfort
26
Diseases Caused by Viruses
• Measles– Rash, fever– Spread by airborne droplets of nasal
secretions
• Mumps– Swelling of the parotid (salivary) glands on
one or both sides– Spread by airborne droplets
27
Diseases Caused by Viruses
• Rubella or German measles– Rash on face may spread to trunk and limbs– Only serious when it affects women in early
stages of pregnancy • May cause birth defects
– Vaccines are highly effective and given to most infants at age 15 months
28
Diseases Caused by Viruses
• Poliomyelitis or polio– Attacks the central nervous system
• Severe paralysis is a possibility
29
Diseases Caused by Viruses
• Chicken pox– Very common and contagious in children– Rash and fever– Spread through airborne droplets– Usually only contract once in a lifetime
• Before age 10 is better than as an adult
30
Diseases Caused by Viruses
• Common cold and influenza– Treatments for fever, upset stomach,
headache, body ache– Cold is spread through airborne droplets,
contact with contaminated objects, or hand-to-hand contact
31
Diseases Caused by Viruses• Common cold and influenza
– Flu vaccines are successful in 60 percent of patients
– Flu is contagious from 12 to 72 hours after symptoms appear
– Flu is spread through airborne droplets
32
Diseases of Major Concern to the Dental Assistant• Herpes simplex virus (HSV)
– Herpes simplex virus I (HSV I) is associated with infections of the lips, mouth, and face
– Herpes simplex virus II (HSV II) is associated with the genital area
• Can also be found in oral cavity
33
• Treatment of HSV I – Depends on its type, site, and severity– Dental teams may reschedule patient if
sores are apparent • Primarily for patient comfort, although some
offices may have policies
– Many treatments readily available
Diseases of Major Concern to the Dental Assistant
34
Diseases of Major Concern to the Dental Assistant• Bloodborne diseases
– Hepatitis B – Human immunodeficiency virus (HIV)
• Brain damage and dementia may occur• May develop into acquired immune deficiency
syndrome (AIDS)– No cure– Much research is being done to find a cure
35
Diseases of Major Concern to the Dental Assistant• High risk behavior
– Injuries or sticks with sharp objects contaminated with blood or body fluid
– Multiple sexual partners; unprotected sex– Sharing contaminated needles– Exposure to non-intact skin or open wound
with contaminated blood or body fluid
36
Diseases of Major Concern to the Dental Assistant• Viral hepatitis
– Hepatitis A and E • Transmitted by personal contact or ingestion of
contaminated water or food • Vaccines and boosters are available for children in
areas at high risk
37
Diseases of Major Concern to the Dental Assistant• Viral hepatitis
– Hepatitis B (major dental concern)• Transmitted mainly through needles and syringes • May or may not have symptoms
– Loss of appetite, abdominal pain and tenderness, fever, weakness, muscle pain, and jaundice
38
How the Body Resists Diseases
• Infection– Pyogenic membrane
• Dam built around infected area preventing it to spread further
– Antibodies• Produced as a final defense against foreign
substances
39
How the Body Resists Diseases
• Infection– Antitoxins
• Neutralizes the toxins given off by certain bacteria
40
How the Body Resists Diseases
• Fever – Fights off infection or pathogens
• Few bacteria can survive beyond 102° F
41
How the Body Resists Diseases
• Inflammation– Increase in blood vessels to a specific area
allowing antibodies to enter• Erythema (redness)• Heat• Edema (swelling)• Pain
42
How the Body Resists Diseases
• Immunity – Ability to resist disease
• Natural • Acquired• Passive acquired • Active acquired • Natural acquired • Artificial acquired
43
How the Body Resists Diseases
• Antigen substance injected into body to stimulate specific antibodies– Allergens– Hypersensitive– Anaphylactic shock
• Sometimes fatal• Requires going through patient’s health history
44
Normal Routes of Microorganism Exposure
• Direct contact– When a dental provider touches the lesion
or blood of an infected person while working in the oral cavity
– Standard precautions
45
Normal Routes of Microorganism Exposure
• Indirect contact– When dental provider or next patient
obtains disease from contaminated instruments, supplies, or equipment
– Standard precautions
46
Normal Routes of Microorganism Exposure
• Inhalation– Takes place during use of high-speed
handpiece• Creates an aerosol spray during patient care