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Microbiology

DA 116 Infection Control

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• Study of microorganisms – Small living organisms

• Important to know– Pathogens = disease-causing microorganisms

• Also called microbes

– Prevent transmission of disease through infection control

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Helpful or Harmful?

• Equally:

– Helpful = non-pathogenic• Ex. Food products: Aged

cheeses, wines, yogurt• Ex. Soil fertilization,

production of life-saving drugs

– Harmful = pathogenic• Ex. Infectious diseases

• Dental Health Concerns – Dental caries = bacteria

(streptocoocus mutans)– Periodontal disease =

bacteria + protozoa

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Bacteria

Protozoa

Fungi

Viruses

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Bacteria

• Singular = bacterium

• Good and bad

• Can live independently under favorable environmental conditions– 98.6°, dark, moist

• Some types require oxygen to grow and survive– Aerobic

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Bacteria: classified by shape

• Cocci (sometimes described as spherical-shaped)

– Chain-shaped• Streptococci

– Strep throat, tonsillitis, pneumonia, endocarditis

– Cluster-shaped• Staphylococci

– Boils, skin infections, pneumonia, endocarditis

• Bacilli– Rod-shaped

– Tuberculosis

• Spirochetes (spirilla)

– Spiral-shaped– Lyme disease, syphilis

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Bacterial Spores

• Most resistant form of life known– Harmless spores used to test sterilization

techniques in infection control

• Caused by unfavorable conditions• Alive, but inactive– Cannot reproduce or cause disease

• If conditions improve, become active and disease-causing

• Examples:– Tetanus, tuberculosis, strep throat

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Protozoa

• One-celled organisms

• Do not cause disease• Live in hosts which

can cause disease – intestinal infections– invade blood, lungs,

liver or brain

• Not usually dental office infection control concern

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Fungi

• Plants– Mushrooms, yeasts,

molds

• Candidiasis– Common yeast found

throughout body– Opportunistic

• Affect very young, very old, or very ill patients

• Oral candidiasis– white membranes on

tissues throughout oral cavity

– common under dentures

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Viruses

• Tiny disease-causing organisms

• Live and multiple only inside a host– Human, animal, plant,

or bacteria– Invades host cell,

replicates, and destroys host cell allowing virus cells to release into the body

• Great concern to DHCW

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Characteristics of Viruses

• Specificity: – some live only in certain cells

• HIV

– others affect only certain organs • Mumps = thyroid, pancreas, testicles, ovaries)

• Latency:– Can be dormant for years and then reactivate

• HIV and Hepatitis C “carriers” (3-5% of adults with HBV)

• Dental Office Concern = herpes simplex– HSV 1 = lips, mouth, face– HSV 2 = genital area– Both can be found in oral or genital areas

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Treatment and Transmission of Viruses

• Treatment: – Viruses can mutate to adapt to new situations– only symptoms, not infective cause (virus)– Immunization EVERY year

• Infection control: easy to destroy in external environment

• Transmission– Direct contact– Indirect contact– Insects– Contaminated food or water

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• http://www.youtube.com/watch?v=9xSJckErbcc&feature=related

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Viral Hepatitis

• Inflammation of the liver• Five types

– HAV Hepatitis A food-borne (fecal/oral) immunization

– HBV Hepatitis B blood-borneimmunization

– HCV Hepatitis C blood-borne – HDV Hepatitis D occurs in HBV or HCV carrier

» (HBV immunization protects against HDV)

– HEV Hepatitis E food or water-borne (fecal/oral)

• Latency– HAV outside body for months– HBV 7 days and still transmit infection– HCV 16 hours – 4 days still transmit infection

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Transmission of Hepatitis Viruses• HAV and HEV

– Fecal/oral• Contaminated food and water• Handwashing and clean food preparation methods

• HBV and HCV– Bloodborne– Contaminated needles or sharps injuries– Sharing needles– Tattoos from contaminated needles or instruments– Infected mothers to newborns

• HDV– Must have had HBV or HCV in the past

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HIV

• Human immunodeficiency virus– Body’s immune system breaks down

• Symptoms can include– fatigue, weight loss, fever and sweats, skin

rashes, short term memory loss

• HIV patient can remain healthy for years• Routes of transmission– Blood, semen, vaginal fluids, breast milk

• AIDS– Acquired immunodeficiency syndrome– Caused by HIV related serious illnesses and

infections

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Always follow Standard Precautions!• Remember:– You cannot know which patients have some sort

of infectious disease by • Looking at them• Talking to them• Reading their medical history forms• Even if they are your family or friends

• Because:– Symptoms don’t always appear until after you’ve

treated the patient, yet the patient can be contagious!

– Symptoms in the blood aren’t visible at all!