DENT 1103 Test 1

Unit 1 and 2

Microbiology

Study of microorganisms - small life forms founded by Pasteur

Microorganisms

More beneficial than harmful to humans

Harmful:

• Spoiling food

• Occluding waterlines

• Causing disease

Types of microorganisms (6)

Major groups

• Bacteria

• Algae

• Protozoa

• Fungi

• Viruses

• Prions (not considered part of “major groups”)

Bacteria

Single-celled varying in size, shape and arrangement, can be aerobic, anaerobic, or facultative

Shapes (3)

• Cocci (spherical, Streptococci are when they form chains)

• Bacilli (rod)

• Spirochetes (curved or spiral)

Specialized forms/ group

• Rickettsiae

• Capsules and spores are found in this type of microorganism

Algae

Most do not produce human disease - note a major concern

• Range from single or multiple cell organisms

• Capsules and spores are found in this type of microorganism

Protozoa

single cell have a complex internal structure either free living or as parasites

• Capsules and spores are found in this type of microorganism

Fungi

Mushroom, yeasts, and molds that lack chlorophyll

• ex candid albicans are commonly found in oral cavity

• Capsules and spores are found in this type of microorganism

Viruses

Smallest of microorganism, ultramicroscopic infectious agents

• Can cause (many) fatal diseases

• Live and multiple only inside an appropriate host cell - some require particular cell types (SPECIFICITY)

• Some become latent/dormate and reactive later LATENCY

• Cannot be destroyed by antibiotics

Prions

Convert normal proteins into dangerous ones by changing their shape

• Abnormally structured form of a protein found in brain not containing RNA or DNA

• Can be hereditary or transmissible

• Highly resistant to heat

Specialized form/structure found in bacteria, algae, protozoa, and fungi

Capsules - protective layer covering cell wall, virulent causing serious disease

• Resists antibiotics from affecting microorganism

Spores - most resistant form of life (HARDEST TO KILL)

• Microorganisms can change to be highly resistant under unfavorable conditions

Strep throat, tonsilitis, pneumonia, endocarditis

Bacterial disease - caused by streptococci (chain of cocci)

Tuberculosis

Bacterial disease - caused by bacilli

HIV and Tb often present together because of weakened immune system

Lyme disease

Bacterial disease - caused by spirochete

Rocky mountain spotted fever

Bacterial disease - caused by Rickettsiae rods

Diseases caused by algae

Do not produce human disease

Malaria

Protozoa disease - acute and chronic vector-borne blood infection

• High fever, chills, severe sweating, organ failure

• RBC rupture and drive symptoms

• Parasites in liver multiply

Toxoplasmosis

Protozoa disease - acute and tissue-borne

• Healthy individuals are asymptomatic

• Immunocompromised individuals experience brain inflammation, organ failure, physical seizer

Candidiasis

Fungi - yeast infection caused by candida species overgrowing in warm moist skin fold (commonly found in oral cavity)

• Bright red moist patches with distinct borders

Tinea pedis (athlete’s foot)

Fungi - contagious mold infection affecting feet

• Between toeas, soles/ sides of feet

• Itchy, peeling, cracked skin

• Barefoot in public damp areas

Tinea corporis (ringworm)

Fungi - dermatophyte infection of skin or trunk or limbs

• ANy part of body besides feet, groin, or scalp

• Circular/ oval patches that are red/ scaly with outer border and moderate to intense itching

• skin to skin contact and contaminated objects

Creutzfeldt-jackob disease

Prion - rare fatal brain disorder caused by toxic misfolded prions that destroy brain cells

• Spontaneously through rare genetic mutation

• can die within 6-12 months

Madcow disease

Prion disease - infectious affecting central nervous system of cattle

• Eating contaminated beef with abnormal prion proteins

• Behavioral changes and loss of coordination

Alzheimers/ dementia

Prion - decline in mental ability and brain disease by abnormal buildup of amyloid plaque killing brain cells

• Age related brain changes combined with genetic lifestyle

• Gradual loss (slow an d progressive) of short term memory, confusion

Hepatitis

• Virus - Inflammation of the liver A-E

• ABC - yellowing in the skin and eyes

• A and E are transmitted through outside factors, no carrier (can’t hide in your body forever)

Carrier - person may appear healthy and not ill but still spread disease to others

HEP A

• Transmitted from outside factors (contaminated food/water, fecal-oral)

• Less serious form, vaccine, no carrier

• prevented with good sanitation

• Short incubation - possibly leads to chronic liver disease

HEP B

• Blood-borne transmitted by direct or indirect contact with infected body fluids

• Very serious: prolonged illness and chronic liver disease or death

• Vaccine, 90% infected completely recover without carrier state

• Long incubation

HEP C

• Blood-borne transmitted by direct or indirect contact with infected body fluids - blood transfusion/ needle stick

• No vaccine, highest carrier rate (most easily spread without symptoms), short incubation

HEP D

• Blood-borne transmitted by direct or indirect contact with infected body fluids

• May cause infection only in the presence of active HEP B

• vaccine of HEP B will protect against HEP D, carrier, long incubation

HEP E

• Transmitted from outside factors (food/water, fecal-oral)

• Most frequently seen in developing countries (contaminated food/water)

• No carrier, no vaccine, short incubation

HIV

• Bloodborne, viral virus - infects and slowly kills T cells

• Symptoms can vary depending on stage - treatment is symptomatic

• Doesn’t always lead to AIDS

• Transmission - needles, sexual contact, blood exposed

AIDs

• Caused by HIV if virus progresses (a stage of HIV)

• Can be treated if caught early

• The end stage (of life) for those with HIV

• symptoms - sever periodontal disease (specific to any HIV/AIDs host)

Modes of transmission (8)

• Direct

• Indirect

• Airborne

• Aerosol, spray, spatter

Other…

• Parenteral

• Blood-borne

• Fecal-oral

• Food and water

Direct transmission

Pathogens transferred by direct contact with infectious lesion or fluid through small breaks

Indirect transmission

Pathogens transferred by organisms to a susceptible person by contaminated instruments or contaminated surfaces then touching mouth, eyes…

Airborne transmission

Disease spread through droplets of moisture that contain bacteria/viruses

Aerosol, spray, or spatter transmission

• Aerosols remain airborne for periods of time that can be inhaled that may contain microorganisms that are infectious

• Sprays and spatter are larger droplets traveling further than aerosol mist

Other modes of transmission (4)

• Parenteral - break in the skin where pathogens occur

• Blood-borne - pathogens carried in fluids of infected individuals and transmitted to others

  • Direct and indirect caused by improperly sterilized instruments

• Fecal/oral - pathogens transmitted when infected person contacts other surface or food

• Food and water - contaminated food improperly cooked

Pathogenic

Microorganisms that are disease producing

• Grow best in moist dark environments at temperatures 37 celcius

Non-pathogenic

Microorganisms that do not produce human illness

Natural immunity

Person previously contracted disease and recovered

• Active - antibodies formed that provide future resistance against the particular pathogen

• Passive - during the fetus receives antibodies from mother

Artificially

Have not been exposed to disease - antibodies are from immunization/vaccination

Stages of infectious disease (4)

• Incubation

• Prodromal

• Acute

• Convalescent

Incubation stage

Period from initial entrace of infectious agent to when first symptoms appear

• Microorganisms must multiply to suficient numbers

Prodromal stage

Appearance of early symptoms

Acute stage

symptoms are maximal potential to spread MOST CONTAGEOUS

Convalescent stage

Recovery stage - numbers of microorganisms (virulence) is declining

Chain of infection (6)

Infectious process

1. Infectious agent

2. Reservoir

3. Portal of exit

4. Portal of entry

5. Susceptible host

6. Mode of transmission

Infectious agent - chain of infection

First link

• Pathogen must be present in sufficient numbers

• Organism that is very virulent can cause serious disease

Reservoir - chain of infection

Second link

• Where microorganisms normally live and reproduce

• Cleaning and disinfecting contaminated surfaces will reduce reservoirs

Portal of exit/entry - chain of infection

Third/fourth link

• Pathogens entering and exiting a host to cause infection

• Airborne pathogens - nose mucosa of eve

• Blood-borne pathogens - access through a blood supply (break in the skin)

Susceptible host - chain of infection

Fifth link

• Person cannot resist infection because of a weakened immune system

• Wash hands, keep immunizations up to date

Mode of transmission - chain of infection

Sixth link

• Disease transmitted from one host to another - direct indirect, blood-borne, etc

Standard precautions

Concept that ALL blood and body fluids are to be treated as if known to be infected with bloodborne disease

• All patients are potentially infective even when asymptomatic

• Same safe standards of practice must routinely apply to contact

Routine practices of standard precautions

• Risk assessment

• Hand hygiene

• Use of personal protective equipment

• Safe handling and disposal of sharps

PPE in dental office

• Clothing - must be changed into/out in workplace and washed

• Masks - less effective when moist

• Eyewear- face shield, client eyewear

• Gloves - nitrile, most critical (one time use)

• Gowns - must worn in recirculation room with contaminated instruments (and during procedures)

Latex reactions (3)

Usually developed after repeated exposure to latex (from gloves, rubber dam)

Three common types:

1. Irritant dermatitis

2. Type IV allergic reaction

3. Type I allergic reaction

Irritant dermatitis - latex reaction

Chemical irritation caused by frequent hand washing - doesn’t involve immune system

• Skin is red, dry irritated

Type IV allergic reaction - latex reaction

Most common - a delayed reaction (48-72h) from contact involving immune system

• Red rash

Type I allergic reaction - Latex reaction

Most serious and can be deadly - severe immunologic immediate response reaction from latex proteins in the glove

Handling for disposal of various types of waste

Classification: Handling, storage, labelling, and disposal of waste depend on type of waste

Types of waste

• General

• Contaminated

• Hazardous

• Infectious or Regulated waste (biohazard)

Biomedical waste:

• Anatomical - human

• Non-Anatomical - blood and blood-soaked materials+sharps

• Non-biomedical

General waste

• Non hazardous, non regulated - disposed in durable plastic or metal container

• Paper towel, paper mixing pad, headrest cover

Contaminated waste

• Had contact with blood or body fluid - dispose in general waste

• Barriers, bib, gauze with minimal trace of blood

Hazardous waste

• Poses a risk to humans and environment

• Chemical amalgam, fixer solutions, lead apron

Infectious or regulated waste (biohazard)

• Compatible of transmitting infectious disease

• Requires special handling and disposal - not in general waste

Anatomical waste

Biomedical waste

• Soft tissue

• Yellow liner bag stored in lockable enclosed area below 4C

• Marked as “Biomedical waste storage area”

Non-Anatomical waste

Biomedical waste

• Blood or saliva can be squeezed out or dried that can flake

• Needles, scalpel blades, wires, endodontic instruments

• Red liner bag

• Separate blood soaked materials from sharps and other biomedical wastes

Non-biomedical waste

• Teeth - amalgam fillings must be collected first

• Saliva-soaked gauze or other material - regular garbage

Types of infection

1. Acute vs chronic

2. Latent

3. Opportunistic

Acute type of infection

• Short duration

• Severe symptoms

• Appear soon after initial infection occurs

Chronic infection

• Microorganisms present for a long time - sometimes for lie

• Can be asymptomatic but still be a carrier

Latent infection

• Persistent infection

• Symptoms come and go

• First causes an original lesion then lies dormant in a nerve cell

Opportunistic infection

• Caused by non-pathogenic organism when resistance is low or compromised

• ex. recovering from one virus but getting an infection in the process

Human immunodeficiency

Virus

• no cure but treatment has progressed

• Progressively destroys the body’s ability to fight infections by killing/damaging cells - T4 Lymphocytes

• Bloodborne

• Symptoms vary based on stage

• Transmission:

AIDs

• Caused by HIV

• End stage of life for those with HIV

• Symptoms - weight loss, night sweats, diarrhea, oral lesions

• Oral lesions: candidiasis, severe periodontal disease (specific to HIV and AIDs)

Primary Herpes

Virus, highly contagious appearing in children 1-3 years

• Lasts 7-14 days

• Swollen mouth and inflamed gingiva, pain in mouth, slight fever

• The first time infection with HSV (herpes simplex virus) when a person comes into contact with the virus

Herpes virus (4 types)

Can be dormant for years then become activated and cause diseases

1. Herpes simplex virus (HSV1 and HSV2)

2. Herpes Zoster virus HZV

3. Epstein Barr virus EBV

4. Cytomegalovirus CMV

Infections from HSV1 and 2

Herpetic whitlow - on hands lasting longer than oral lesions

Ocular herpes - eyes, may cause blindness

HSV1

Herpes simplex virus

Oral lesions, viral infection causing sores on lips

HSV2

Herpes simplex viruses

• Genital herpes

• Symptoms 10 days after infection

• Most common sexually transmitted only during an outbreak

HZV

Herpes Zoster Virus - human herpes type 3

• Causes chickenpox and shingles

• Chickenpox is the primary infection, HZV represents the reactivation of the illness

• Very contagious, spread through direct contact

EBV

Epstein Barr virus - human herpes type 4

• Various infections: mononucleosis, lymphoma and hairy leukoplakia

CMV

Cytomegalovirus - human herpes type 5

• Rarely causes disease unless other factors are preset

Ex. compromised immune system

• Rout of transmission is unclear

Pandemic

Three conditions must be met:

1. Emergence of a disease NEW to a population

2. Agent infects humans causing SERIOUS ILLNESS

3. Agent SPREADS EASILY and sustainably among humans