Class 3 Flashcards
All living creatures share 2 basic objectives in life which are?
1) survival
2) reproduction
All living creatures share 2 basic objectives in life:
1) survival
2) reproduction
to satisfy these goals, organisms must do what?
Extract from the environment essential nutrients.
-can benefit both organisms or produce harmful &
potentially lethal consequences.
Consequences of these invasions are called _______________.
infectious diseases
What is a host?
any organism capable of supporting nutritional & physical growth requirements of another organism.
What is infectivity?
ability of organism to enter, multiply & survive in host
What is infection?
presence & multiplication within host that results in injury to host
What is colonization?
act of establishing a presence within a host
T/F All interactions between microorganisms and humans are detrimental?
False - NOT all interactions between microorganisms and humans are detrimental
What is microflora?
multitude of non-harmful bacteria that inhabit internal & external exposed surfaces of human body.
Microflora can be found in what?
• Skin
• Nose/Pharynx
• Mouth
• Colon/Rectum
• Vagina/Distal Urethra/Perineum
What is commensalism?
Colonizing organism benefits & host is NOT adversely affected by it
What is Mutualism?
Colonizing organism & host both derive benefits
What is Parasitic?
Colonizing organism benefits & host gains nothing or sustains injury
Infectious disease can vary in severity and can be due to
______________________ and ______________________________.
• host health
• virtulence of the organism
What is Virulence?
Disease producing potential of invading organism.
__________________ are an example of a highly virulent organism and are rarely found in the host when there is no disease.
Pathogens
What are Saprophytes?
Harmless, free living organisms that obtain nutrition from dead or decaying organic materials in environment.
What is an Opportunistic Pathogen?
An organism which is capable of producing an infectious disease only when health & immunity of host have been severely compromised.
What are Prions?
• protein particles that lack any kind of demonstrable genetic material.
• mutated forms of normal host protein.
• may affect other normal proteins & alter them.
• aggregate in brain & form plaques.
• have been identified in number of incurable &
transmissible degenerative neurological diseases
• defective protein may be inherited.
• Transmissible degenerative neurological diseases are
all characterized by slowly progressive, non inflammatory neuronal degeneration, leading to loss of coordination (ataxia), dementia & death ranging from months to years.
• Current antimicrobial agents are useless against them
therefore treatment is palliative.
Prions have been identified in a number of incurable &
transmissible degenerative neurological diseases such
as?
• Creutzfeldt-Jakob disease
• Kuru
• Mad Cow disease
Rickettsia, Chlamydia, Coxiella, Mycoplasma are organisms that combine characteristics of ______________ and ______________.
viruses and bacteria
What is Rickettsiacecae?
- Live inside host cell since they rely on host cell for vitamins & nutrients
- Transmitted by insect vectors/bite of arthropod (fleas, ticks & lice)
- Produce number of potentially lethal diseases
Ex. Rocky Mountain Spotted Fever & Epidemic Typhus.
What is Chlamydiaceae?
• Scavenge intermediates of energy metabolism, like ATP.
• Transmitted directly between susceptible vertebrates
without intermediate arthropod host.
Ex. Sexually transmitted infection Chlamydia which can lead to pelvic inflammatory disease & sterility in women. Infants born to infected mothers can develop eye infections & pneumonia.
What is Coxiella?
• Infects variety of animals & in humans produces
illness often called Q fever, illness that presents with flu-like symptoms, & cause progress to become systemic
affecting heart, lungs, & GI.
What is Mycoplasma?
• Capable of independent replication.
• Resistant to cell-wall binding antibiotics like Penicillin.
• In humans, they are commensals but some species are
capable of producing serious diseases including pneumonia, genital infections & maternally transmitted respiratory infections to infants with low birth weight.
What is fungi?
• free living saprophytes found in every habitat on earth.
• some are part of normal human microflora.
• few are capable of causing disease in humans & when they do, they are infections of skin & subcutaneous tissue.
• serious infections are usually initiated through puncture wounds or inhalation.
• can cause life threatening opportunistic diseases when host has been weakened.
What are the 2 groups of fungi?
- Yeast
- Molds
What is yeast described as?
smooth with a waxy or creamy texture
What are moldes described as?
cottony or powdery texture that can penetrate growth surface or project above
What are yeasts and molds?
• Yeasts & molds produce rigid cell wall layer which makes it not susceptible to effects of antibiotics.
• Can reproduce disease in humans only if they can grow at
temperature of infected body site.
Ex. Athletes Foot- fungal infection, scaly rash, contagious,
OTC meds
What is Candida?
Type of yeast that is commensal flora of skin, mucous membranes & GI tract, are capable of growth at wider range of temperature. Alterations in immune system by disease or antibiotic therapy can upset balance & result in overgrowth, setting stage for opportunistic infection.
What are types of parasites?
• Protozoa
• Helminths (a.k.a. Worms)
• Arthropods
What is Protozoa?
• most are saprophytes but few have adapted to accommodations of human environment & produce variety of diseases, for example Malaria.
Transmission of Protozoa?
host to host through sexual contact or indirectly from
water or food or by arthropod vector.
What are Helminths (a.k.a. Worms)?
• humans can serve as definitive or intermediate
host or as both.
Transmission of Helminths (a.k.a. Worms)?
ingestion of fertilized eggs or penetration of infectious larval stages through skin (Ex. Roundworms, tapeworms, flukes)
What are Arthropods?
• vectors of disease such as ticks, mosquitoes, biting flies, lice, fleas & mites infest external body surfaces & cause localized tissue damage or inflammation secondary to bite or burrowing action of arthropod.
Transmission of Arthropods?
directly by contact with any form of arthropod or its
eggs to human, clothing, bedding or grooming articles.
What is Epidemiology?
study of factors, events, & circumstances that influence transmission of infectious disease in human populations.
Epidemiology focuses on?
• Incidence of disease
• Prevalence of disease
• Source of infection
• Portal of entry
• Site of infection
• Virulence factors
• Signs & symptoms
• Clinical course of disease
The ultimate goal of epidemiologic studies?
Ultimate goal of epidemiologic studies are interruption of spread of infectious disease & its eradication.
Source of Infection can be __________________ or _______________.
Endogenous or Exogenous
Infection can be transmitted by?
• Source of infection can be another person.
• Contact transmission
• Droplet transmission
• Airborne transmission
• Vector born transmission
• Vehicle born transmission
What are locations that are sources of infection?
• Nosocomial infections/ hospital acquired infections
• Community acquired
• Based on their portal of entry
- Penetration
- Direct contact
- Congenital infections
- Ingestion
- Inhalation
- Droplet infection
- Airborne infection
What is Site of Infection?
refers to part of body that is infected.
• Local infection
• Systemic, or generalized infection
What is Pathogenicity?
Capacity of microorganism to cause disease or make you sick.
What is Virulence?
Disease producing potential of invading organism is based on the following:
• Invasive qualities
• Toxic qualities
• Adherence to tissue
• Ability to avoid host defences
What are Universal precautions?
Universal precautions include hand washing, wearing gloves, & personal protective clothing.
* Hand washing is most effective way to stop spread of most common pathogens.
___________________ is most effective way to stop spread of most common pathogens.
Hand washing
What are sterilization of fomites?
inanimate objects capable of transmitting pathogens – by methods such as autoclaving.
How can we control transmission of infection?
• Universal precautions include hand washing, wearing gloves, & personal protective clothing. Hand washing is most effective way to stop spread of most common pathogens.
• Reservoir or source of infection must be located & removed.
• Portal of exit of microbes should be blocked (like by covering your mouth when you cough)
• Knowledge of mode or modes of transmission of pathogen is essential to block transmission.
• Reduce host susceptibility by immunization, proper diet, & nutrition.
• Adequate cleaning of surroundings & clothing.
• Use of disinfectants (that destroy microorganisms & their toxins on inanimate objects) & antiseptics (that are applied to the skin, to destroy microorganisms)
• Sterilization of fomites – inanimate objects capable of transmitting pathogens – by methods such as autoclaving
What is Symptomatology (a.k.a. clinical picture; disease presentation)?
Refers to collection of signs & symptoms expressed by host during disease course.
• outward expression of struggle between invading organisms & hosts response of inflammation & immune reaction.
• can be specific & reflect site of infection or nonspecific & shared by many diverse infectious diseases. Ex. pneumonia vs myalgia.
• can be obvious or covert. ex. chicken pox vs increased WBC count
Examples signs and symptoms of Symptomatology include?
• Fever & chills
• Increased pulse & respiratory rates
• Aches, pain, or tenderness
• Fatigue & loss of energy
• Loss of appetite, nausea, vomiting, & diarrhea
• Rash, redness, & swelling of body part
• Sores on mucous membrane
What are the phases of disease course?
- Incubation period
- Prodromal stage
- Acute stage
- Convalescent stage
- Resolution stage
What is the Incubation period of disease course?
Pathogen begins active replication without producing symptoms.
What is the Prodromal stage of disease course?
Initial appearance of symptoms that usually show as vague sense of malaise.
What is the Acute stage of disease course?
Host experiences maximum impact & has most symptoms.
What is the Convalescent stage of disease course?
Containment of infection, progressive elimination of pathogen, repair of damaged tissue, & resolution of associated symptoms.
What is the Resolution stage of disease course?
Total elimination of pathogen from body with no residual signs or symptoms.
There are some exceptions to the classical presentation which include?
• Chronic infections
• Subclinical/ sub-acute illness
• Insidious
• Fulminant
Diagnosis (Dx) is based on?
• History
• Physical examination
• Culture- propagation of a microorganism outside of body.
• Serology- study of serum to measure antibodies in diseased host
Types of Treatment (Tx)?
• Antimicrobial agent- use of certain substances that were useful for preventing or curing wound infections.
• Immunotherapy- supplementing or stimulating hosts immune response to limit or reverse spread of pathogen.
• Surgical intervention- previously only available option to prevent host death.
What are Bacterial Infections?
• Bacteria are microscopic, single celled organisms
(prokaryotes).
• There are thousands of different kinds, they live in every conceivable environment
• Only few kinds of bacteria cause disease
• Sometimes bacteria that usually reside harmlessly in human body may cause disease
• Can cause disease by producing toxins, invading tissue, or both
What are scientific names?
• Classified by species
• Within species there may be different types (strains) which differ in genetic makeup, & chemical components.
What is Staining?
Bacteria may be classified by colour they turn after they are treated with certain chemicals (stains).
The most common stain is?
Gram Stain
Gram-positive turns _____________ when stained
purple
Gram-negative turns ______________ when stained
pink
What is Gram -positive and -negative bacteria?
Gram -positive & -negative bacteria have differences in their cell wall structure. They cause different infections, & they response differently to antibiotics.
All bacteria may be classified as one of 3 basic shapes?
- Spheres (cocci)
- Rods (bacilli)
- Spirals (spirillum)
Bacteria are classified by whether they need oxygen to live and grow. What are the three classifications?
• Aerobes
• Anaerobes
• Facultative
What does bacterial structure consist of?
• Outer ridge cell wall
• Cell membrane
• External capsule
• Flagella
• Pili, or fimbriae
• Spores
Toxins and enzymes may be secreted by bacteria, what are the 2 types of toxins?
- Exotoxins
- Endotoxins
What happens to Exotoxins?
diffuse through the body
What happens to Endotoxins?
released when the bacteria dies
What produces Enzymes & whats their effect to host?
produced by some bacteria & cause damage to host tissue.
Bacteria have different ways to defend themselves from the host’s immune system such as?
• Biofilm
• Capsule
• Outer membrane/cell wall
• Spores
• Flagella
• Antibiotic resistance
What is Staphylococcal (Staph) Infections?
• There are more than 30 strains of staphylococcus.
• Most are produced by Staph Aureus.
Common infections include?
- Skin infections
- Cellulitis
- Pneumonia
- Food Poisoning
- Breast abscesses
- Postoperative infections
- Toxic shock syndrome (TSS)
- Bactermia
What is Streptococcal (Strep) Infections?
• Strep comes in strains from A to G.
• The most common infections arise from groups A and B strep
What is Group A Strep?
Bacterium commonly found in throat & on skin, can cause a range of infections from relatively mild sore throats & skin infections to life threatening invasive disease
What are key features of Group A Strep?
• Spread by person to person contact
• Symptoms usually start 1-3 days after exposure
• S/S depend on type of infection, but typically present with inflammation
Strep A can lead to?
• Strep throat
• Scarlet fever
• Impetigo
• Toxic Shock Syndrome (TSS)
• Necrotizing Fasciitis
What is strep throat
Where bacteria resides in nose & throat.
• May spread person to person from inhaling droplets
• S/S of strep throat usually develop within 3 days of exposure.
• Include red & white patches on throat, difficulty
swallowing, tender, swollen glands, enlarged tonsils, HA, fever, abdominal pain, anorexia, nausea, & general malaise.
What is Scarlet fever?
Bacterial toxins cause a scarlet coloured rash.
What is Impetigo?
Skin infection
What is Necrotizing Fasciitis (fleshing eating disease)?
Severe inflammation & tissue necrosis due to infection by highly virulent strain. Invades tissues rapidly, reducing blood supply & secretes enzymes that digest tissue. Systemic toxicity may lead to organ failure.
What is Group B Strep?
• Carried by most people without causing illness.
• Can cause serious infection to weakened immune system.
• May be transmitted to newborns from their mothers.
• Most common cause of blood infections & meningitis in newborns.
Strep B can lead to?
• Urinary Tract Infections (UTI)
• Blood infections
• Skin infections
• Pneumonia
What is Rheumatic Fever?
• Inflammatory disease that may develop after strep infection.
• May affect heart, joints, skin, & brain.
• Can lead to Endocarditis & be an issue later in life.
• Mainly affects children from ages 6-15.
Symptoms of Rheumatic Fever include?
• Abdominal pain
• Fever
• Cardiac problems that may be asymptomatic, or present with dyspnea (shortness of breath) or chest pain
• Joint pain, joint swelling
• Nosebleeds (epistaxis)
• Shin nodules
• A ring, or snakelike rash
What is Bacterial Meningitis?
• Serious infection of protective membranes of brain
& spinal cord (meninges).
• S/S include high fever, headache, stiff neck, nausea, & vomiting.
• Patients will be positive for Brudzinski’s sign (neck flexion will cause hip & knee flexion) or Kernig’s sign (extreme pain with hip flexion & knee extension)
• Bacteria may spread by direct close contact with
discharges from nose or throat of infected person.
• Can be treated with antibiotics
• Prevention depends on use of vaccines & rapid
diagnosis.
What is Brudzinski’s sign?
Neck flexion will cause hip & knee flexion
What is Kernig’s sign?
Extreme pain with hip flexion & knee extension
Upper respiratory tract infections include infections like _______________.
strep throat
-Lower respiratory infections include _____________________ and _____________________.
bacterial pneumonia and bronchitis
Tx for both URT and LRT is __________________.
antibiotics
What is Tuberculosis?
• Lung infection caused by mycobacterium tuberculae.
• Bacteria with waxy capsule that makes it hard for macrophages to destroy them.
• Bacteria may remain dormant in granulomas in lungs called Ghon Foci. If ghon foci rupture, then active case of TB begins.
• Bacteria may spread to any part of body, & cause inflammation & damage to lung parenchyma.
What are Enteric Bacterial Infections?
infections of the intestines
Some of the bacteria that cause enteric selections are?
• Escherichia coli (E.Coli)
• Vibrio cholera (causes Cholera)
• Salmonella
• Shigella
• Anaerobic Streptococci
What is Salmonella Infection?
• more than 2000 varieties
• about 10 are pathogenic to humans
• most known as Gastroenteritis
• S/S start 12-72 hours after exposure to bacterium, lasts for about 5-7 days, usually resolves without treatment & includes nausea, vomiting, diarrhea, abdominal cramps, fever.
• few varieties can lead to Typhoid Fever, a sometimes deadly disease, more common in developing countries. Incubation period ranges from 5-21 days, S/S last 7-10 days. Symptoms include diarrhea/constipation, high fever,
bradycardia, raised red spots on upper chest,
enlargement of the liver & spleen. Can be treated with antibiotics
What is Shigella Infection (a.k.a. Shillosis)?
• common in settings where hygiene is poor.
• spread via fecal-oral route.
• S/S start 2 days after exposure, resolve after 5-7 days.
• symptoms include fever, diarrhea (often blood) abdominal cramps, dehydration.
• treatment usually palliative & antibiotics may be used.
• anti-diarrheals should be avoided.
• can be prevented by using hygienic food prep & hand washing.
What are Bacterial Infections of the Urinary Tract?
• affect urethra, urinary bladder, ureters, & kidneys.
• commonly caused by gram negative bacteria such as e. coli, pseudomonas aeruginosa, & klebsiella.
• S/S include urinary frequency & urgency, dysuria, lower abdominal pain, & flank pain.
• diagnosis determined with urine test & culture.
• prevention by proper hygiene
• treated with antibiotics.
What is Lyme’s Disease?
• most common tick-borne infection in northern hemisphere.
• S/S include headache, fever fatigue, depression, followed by target shaped rash known as erythema migrans or “bulls-eye rash” then may involve joints,
heart & CNS.
• can be treated by antibiotics but it’s difficult illness to treat, some patients must be treated with multiple doses over years.
