Lecture 1 Flashcards
What are the 3 domains of life?
Archaea, Bacteria, and Eukarya
What are archaea?
microorganisms that live in extreme environments
Can archaeal microorganisms cause microbial diseases?
Possible but not many is known
What domains of life represent the prokaryotes?
bacteria and archaea
What are the 3 main differences between prokaryotes and eukaryotes?
membrane-bound organelles, nucleus, and size (eukarya = bigger)
What are the main differences between gram (-) and gram (+) bacteria?
gram+ = NO periplasm and stains purple/blue; thick peptidoglycan || gram– = peptidoglycan, periplasm, outermembrane, stains pink/red
What is a characteristic of an outer membrane in terms of gram staining?
outer-membrane prevents most stains from penetrating
What affects the penetration of stains?
presence of outer membrane
What is a periplasm?
space located between the peptidoglycan layer and the 2 membranes (outer and cytoplasmic)
Which bacteria has a thinner cell wall?
gram–
What are the 4 types of bacteria?
gram+, gram–, mycoplasma, and acid-fast
What is unique about the outer structure of mycoplasmas?
they ONLY have the cytoplasmic membrane, no cell wall or outer-membrane
What is the outer structure of acid-fast bacterium?
very similar to gram+, has basic components = peptidoglycan and cytoplasmic membrane
What does cell morphology refer to?
the shape the bacteria takes and how it colonizes
Who discovered the microscope at what year?
Robert Hooke in 1600s
Why is it important to know when the microscope was first discovered?
science of microbiology began to develop after the discovery of the microscope
When is the Golden Age of Microbiology?
1850-1910
What are some contributions Louis Pasteur made to science?
discoveries in microbiology and immunobiology, vaccines, pasteurization (steriliztion technique)
Who is the Father of Microbiology?
Louis Pasteur
Who is the Father of Medical Microbiology?
Robert Koch, general physician
What was the Germ Theory of Disease?
linked infectious diseases to certain pathogenic microorganisms proving that those microorganisms are the cause of those IDs
What are Koch’s Postulates?
proved infection caused by particular microbe caused death ||| took samples from dead animal > isolated specific colonies > infect animal with those colonies > animal died > was able to isolate same specific colonies
What were the contributions Robert Koch made?
Germ Theory of Disease, Koch’s Postulates, pure culturing techniques
What are antibiotics?
a chemical substance produced by a microorganism that kills or inhibits the growth of another microorganism
What are antimicrobials?
targets all microbes
What is an antitoxin?
antibody counteracts toxin
What is bacteremia?
presence of bacteria in the blood
What is bacterial envelope?
cell envelope from cytoplasmic membrane and other
What is a chronic infection?
persistent/long-term infection
What is commensalism?
A benefits B but B neither benefits/harms A
What is an endospore?
a bacterial cell developed into spore
What is a fomite?
an object that can be contaminated with infectious microbes and serve in their transmission
What is hemolysin?
protein that lyses RBCs
What is an infection?
invasion into host tissues/organs/cells by a pathogen
What is an inflammation?
part of body that has become reddened/swollen/hot
What is an opportunist?
pathogens that take advantage of an opportunity not normally available
What is an outbreak?
sudden start of something
What is a parasite?
organism living in/on another organism and benefiting other organism at its expense
What is pathogenicity?
ability of an organism to cause a disease
What are R-plasmids?
plasmids with antibiotic resistance genes
What are siderophores?
molecule that binds/transports iron in microbes
What is a toxin?
microbial product that damages the target cell
What is a toxoid?
inactivated toxin used in vaccine development
What can toxoids be used for?
as an antigen for vaccine development
What are vaccines?
substance used to stimulate antibody production
What is virulence?
severity/harmfulness of a disease
What is a virulence factor?
agents produced by pathogen for pathogenesis
What is zoonosis?
diseases that can be transmitted from animals to humans
What are the 6 stages of an infectious disease (ID)?
EESMDO - encounter > entry > spread > multiplication > damage > outcome
When do we first encounter microbes and what does this mean?
at birth = means fetus lives in a sterile environment
What do “congenital infections” mean?
infections before birth
When would one contract a congenital infection?
when mother has an infectious disease that can be passed to newborn child prior to delivery
What are some examples (3) of congenital infections?
AIDs, HIV, syphillus
Does encounter always mean it will lead to an infectious disease, why or why not?
No due to host cell defensess
What are some factors that contribute to one’s susceptibility of contracting an infectious disease?
gender, overall health, how many microbes we encounter, and age
What are the 2 types of encounter?
exogenous and endogenous
What does an exogenous encounter mean?
the microbial agent is from the environment
What does an endogenous encounter mean?
the microbial agent is present in or on the human body (normal flora)
What does “ingress” mean?
entry without crossing epithelial barriers (ie: via toxins); damage caused by the product of a pathogen (ie: botulism)
What does “penetration” mean?
whole pathogen enters into a tissue after crossing epithelial barrier
What are some ways “penetration” entry can occur?
via receptors, insect bites, cuts/wounds, organ transplants or blood infusions
What is the common form of entry?
penetration
How does “ingress” entry work?
pathogen stays outside of the cell but sends one of its microbial factors it produces
How do exogenous pathogens enter our bodies?
through one of the openings we have (ie: nose, mouth, vagina, cuts/wounds)
What is “spread”?
pathogens want to infect more than one part/side of the body so they scatter (“spread”) to those parts starting from the origin of entrance
What does spread depend on?
anatomical factors such as bloodstream which can take them to different parts of the body
Do all microbes spread the same way?
No, some evolved different microbe-specifc mechanisms to spread = takes them from one site to another
Why do microbes spread?
look for the best environment to multiply and flourish = why they use host (provides protection from extreme environments)
What is “multiplication”?
the reason why they spread; make new progeny
How does multiplication play a key role in infectious diseases?
if microbe doesn’t multiply to enough high numbers to cause an infectious disease = will have no symptoms = no existence of a disease
What is an asymptomatic infection?
when multiplication numbers remain low
When will multiplication of microbes develop into a disease?
when the multiplication reaches a certain high number and remains at that number = will release toxins = continue to damage the host
When can recovery or cure occur?
when the damage and multiplication number significantly decreases
What is key to determine the outcome of an infectious disease?
the multiplication number and type of damage
What is the normal microbiota composed of?
the different types of microorganisms frequently found in or on the bodies of healthy individuals; they are non-pathogenic with some exceptions
What is the reason why not everyone has the same microbiota?
due to different exposure, diet, what nutrients we have inside of us || what our bodies supply dictate which microorganisms can survive/thrive there
Define “normal microbiota”
commensal organisms that coexist with humans without causing harm
What are transient members of the normal microbiota?
pathogenic microbes found in normal microbiota of some individuals
What does it mean when a microbe becomes “opportunistic”?
when these microbes find the opportunity to cause/develop an infectious disease
What are the sites colonized by normal microbiota?
skin, respiratory tract, digestive tract, urinary tract, genital system
What are the sterile sites of the body?
any site not following the tube from the mouth/nose to anus/vagina/urethra
Why do we have normal flora in/on our bodies?
help with absorption of nutrients, metabolic function, immune stimulation (cross-reactivity), keeping out invaders (bacteriocin)
What is cross-reactivity when it comes to immune stimulation?
antigen/antibody interaction
What is a bacteriocin?
protein produced by one bacterial strain targeted against those of a closely related strain; doesn’t damage organs
What is a benefit of colonizing certain parts of our organ systems?
to prevent other pathogens and microorganisms from entering our bodies
What is at least one member of the normal microbiota that can cause cancer in some individuals and why?
H. pylori because it is a transient member that can become opportunistic
What are some ways/mechanisms have our bodies developed to prevent pathogens from entering and colonizing?
secretions that contain antimicrobials such as that in tears and saliva
What are the 2 bacterial species of the normal microbiota on the skin?
staphylococcus and corynebacteria
What factors influence the skin microbiota?
weather, age (skin composition), personal hygiene
Which type of bacteria survive better in dry conditions and why and what does this mean?
Gram+ survive better in dry conditions due to their thick cell wall therefore we most often find gram+ species on skin
Which part of the respiratory tract is colonized by microbes and which part is sterile?
upper is colonized by microbes and lower is sterile
What species colonize the normal microbiota of the respiratory tract?
Staphylococcus, Corynebacteria, Streptococcus, Haemophilus, Neisseria
How is the oral cavity a complex environment?
two different types of surfaces bacteria can grow = bones and epithelial tissue
How is bone in the oral cavity an additional bonus to the colonization of microbes?
bone is a great surface for microbes to colonize
Which part of the body will give the normal microbiota the most nutrients?
oral cavity = where we uptake food and fluids = easily allows microbes to multiply
What is an example of an antimicrobial that is secreted by the oral cavity?
lysozyme
What species are present in the normal microbiota of your oral cavity?
Actinomyces, Borrelia, Streptococcus
What is the GI tract composed of?
Stomach, small and large intestines
What characterizes the stomach?
very low pH (~2)
Which part of the body has the largest biomass of bacteria (number?)? Does this mean an increase in variety of species present?
GI tract at 10^4; not variety in species
What species are present in the normal microbiota of your GI tract?
Heliobacter, Escherichia
Which part of the urinary tract is colonized by normal microbiota and which is sterile?
upper is sterile and lower is colonized by normal microbiota (urethra)
Where is the location of a UTI infection and which species is mainly responsible for it?
bladder and Escherichia
What species are present in the normal microbiota of your urinary tract?
Streptococcus and Escherichia
In what gender and body part of the human body can be colonized by normal microbiota? What characterizes this area?
Female’s vagina at a weakly acidic pH
What species are present in the normal microbiota of a vagina?
Streptococcus, Escherichia, Lactobacilus
What is the Human Microbiome Project?
sequenced 16S rRNA to identify the types of microbes in body sites of 242 healthy individuals
What were the findings of the Human Microbiome Project?
discovered which species were more dominant in which areas of the body
What is H. pylori a member of what organ?
stomach
How can we have a sterile organism that lack a normal microbiota to study the normal microbiota?
generate a sterile animal in the lab and determine what effect the microbiota has on the physiology of the host and pathogenesis
What is a side effect on the normal microbiota when taking antibiotics?
antibiotics will not only target the pathogen but also the normal microbiota as well
What is a new concept that challenges the old one when linking an infectious disease to the presence of a pathogen?
perhaps an infectious disease can occur by the absence of a good microbe from your normal microbiota that allowed a bad microbe to take over and flourish due to use of antibiotics
In the Human Microbiome Project, why were there more samples taken from women?
female body is more complex
How many microbes are in our normal microbiota (based on the Human Microbiome Project)?
100x more than our total body cells
On average, how many species are present on our normal microbiota?
about 10,000
