10 Microbiology. 2 Important People in Microbiology Anton Van Leeuwenhoek –Magnifying glass Saw...

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Microbiology

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

• Louis Pasteur– Process of fermentation

• Proved bacteria causes disease

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

• Richard Julius Petri– Petri dish– Further developed technique for

dispensing the bacteria onto the medium

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

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

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

• Diphtheria– Severe throat infection and fever

• Pertussis– Respiratory disease – Mainly affects infants and young children

• Tetanus– Stiffness of the jaw (“lockjaw”)

• Strep throat– Very common– Sore throat, fever, general malaise– Streptococcus mutans

• Species of the same bacteria• Implicated in dental caries and endocarditis

• Staphylococcal infections– Bacteria groups grow in clusters

• Antibiotics are the first line of treatments

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

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

Protozoa

• Just below visibility of the naked eye

• Always dividing and changing shape

• Flagella– Many have this long, threadlike appendage

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

• 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

• Malaria– Symptoms during the first two weeks

• Fever and soreness at point of entry

Rickettsiae

• Parasites cannot live outside a host– Lice, fleas, ticks, and mites transmit

disease to humans

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

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

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

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

• Tinea – Appearance named according to site

infected• Tinea pedis (Athlete’s foot)• Tinea corporis (Ringworm)• Tinea unguium

– White patches on toe or fingernail

• Prion (pree-on) – Proteinaceous infectious particles made of

only protein• Mad Cow Disease• Creutzfeldt-Jacob Disease

Viruses

• Must live inside hosts

• Antibiotics cannot kill the virus

• Treatment is primarily to ease the symptoms for the patient’s comfort

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

• 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

• Poliomyelitis or polio– Attacks the central nervous system

• Severe paralysis is a possibility

• 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

• 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

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

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

• 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

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

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

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

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

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

• Infection– Antitoxins

• Neutralizes the toxins given off by certain bacteria

• Fever – Fights off infection or pathogens

• Few bacteria can survive beyond 102° F

• Inflammation– Increase in blood vessels to a specific area

allowing antibodies to enter• Erythema (redness)• Heat• Edema (swelling)• Pain

• Immunity – Ability to resist disease

• Natural • Acquired• Passive acquired • Active acquired • Natural acquired • Artificial acquired

• Antigen substance injected into body to stimulate specific antibodies– Allergens– Hypersensitive– Anaphylactic shock

• Sometimes fatal• Requires going through patient’s health history

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

• Indirect contact– When dental provider or next patient

obtains disease from contaminated instruments, supplies, or equipment

– Standard precautions

• Inhalation– Takes place during use of high-speed

handpiece• Creates an aerosol spray during patient care

10 Microbiology. 2 Important People in Microbiology Anton Van Leeuwenhoek –Magnifying glass Saw...

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