Med Micro Module 1 Quiz 1

What is medical microbiology?

study of human pathogens and diseases, the interaction between humans and microorganisms

What are the cellular microbes in the body?

bacteria, fungi, protists

What are the acellular microbes in the body?

Viruses and prions

What is studied in medical microbiology?

nature, pathogenesis, epidemiology, and control of disease-causing agents

What is an additional concern of medical microbiology?

development of diagnostic and therapeutic strategies

What other fields intersect with medical microbiology?

bacteriology, mycology, parasitology, virology, immunology, public health, and epidemiology

What are the effects of microbes in the human body?

can be beneficial or harmful

In what way can microbes be commensals?

microbes get habitat and food from humans

How do microorganisms protect humans from highly virulent microorganisms?

"they stimulate immune response in the human host, they aid in antibody production, the natural microflora resists colonization of exogenous pathogenic microbes

What is the role of microbes in digestion?

microbes help metabolize food and break down nutrients used by cells

What are the biochemical or metabolic impacts of microbes on the host?

vitamin production, amino acid synthesis, gas production, odor production, organic acid production, enzyme production, steroid metabolism

In what way are microbes harmful to humans?

microbes can be the causal agents of diseases

What are other names of the normal microbiota?

Normal Microbial Flora, Normal Microflora

What is the normal microbiota?

population of microorganisms that inhabit the skin and mucous membranes of healthy normal persons

What is a microbiome?

collective term for the genomes of the human microbial symbionts

What is the host-microbiome supraorganism?

comprised of the human body and its associated microbes

Which provided the first glimpse of the microbial diversity of healthy humans and is exploring the possible relationships between particular human diseases and the microbiome?

Human Microbiome Project

How many (and who) did the human microbiome project sample?

242 individuals, healthy american medical students

How many body sites did the human microbiome project sample from?

15-18 body sites depending on sex

How many time points were the sampling done?

1-3 time points

How was the data from the human microbiome project processed?

"16S rRNA gene sequencing and limited metagenomic analysis"

What is the purpose of the human microbiome project?

"Develop baseline information about what constituted a "healthy" microbiome"

How many bacterial genomes was sequenced by the HMP?

~3000

What types of profiles/datasets did the HMP produce?

Integrated datasets of metagenomic, transcript, protein, and metabolite profiles from both microbiome and the host

What is the dominant microbe in the skin?

Propionibacterium; Actinobacterium

What is the dominant microbe in the saliva?

Streptococcus; firmicutes

What is the dominant microbe in the urogenital tract?

Lactobacillus; firmicutes

What is the dominant microbe in the gastrointestinal tract?

Bacteriodetes

What are the clinical benefits of knowing a person's microbiome?

"development of biomarkers for predicting predisposition to specific diseases, design of therapies and supplements"

How does knowing a person's microbiome help in the design of therapies and supplements?

used in drug therapies and for tailor-made probiotics

What is done for recurrent or refractory C. difficile infections (CDI)?

Fecal Mircobiota Transplant (FMT)

When does colonization start?

at birth

Is the normal microbiota dynamic?

Yes, it changes as one ages

Where was bacterial DNA found? (in relation to birth)

amniotic fluid, placenta, meconium (baby's stool)

Where do babies of vaginal delivery get their dose of bacteria?

in the vagina, as they pass through the birth canal

What factors influence the makeup of a baby's microbiota?

diet, antibiotic/drug intake, human interaction, environment, genetic makeup

What can happen if children aren't exposed to a wide variety of microbes?

more likely to develop autoimmune and allergic conditions such as asthma and eczema; hygiene hypothesis

What is a less diverse microbiota associated to?

inflammatory bowel disease, obesity, and type 2 diabetes

What is the ratio of microbes to human cells?

1.3:1

What should be the relationship between the microbe and the host in the normal microbiota?

commensals or mutualism, they shouldn't be pathogenic under normal conditions/in their proper location

When is the microbiota pathogenic?

coincident abnormalities, shift in the normal microbiota, and introduction into foreign locations in large numbers

What influence the normal microbiota?

physiologic factors, lifestyle, and genetic factors in humans

What are the characteristics of the normal microbiota?

Colonization begins at birth, About the same as the number of human cells in a single person, Considered harmless commensal or in mutalistic relation with the host, Influenced by physiologic factors, lifestyle, and genetic factors in humans, Individuality (uniqueness), Resilient, Not essential to life

How unique are the species in the normal microbiota?

more evident similarities at higher bacterial taxonomic levels (phyla, family, genera), more differences at the species and strain levels

What is the manifestation of the resilience of the human microbiota?

tremendous plasticity, quick response to disturbances

What are resident microflora?

fixed types of microorganisms, regularly found in a given area at a given age, promptly reestablishes itself if disturbed

What are transient microflora?

"Does not establish permanently, Derived from the environment, Does not produce disease unless resident microbiota is disturbed"

Can life exist without the normal microbiota?

Yes, but the quality of life is different, one can be unhealthy/not normal

What is a gnotobiotic mice?

mice that are born germ-free but inoculated with a panel of microorganisms

What are the biological roles of the normal microflora?

Assists in digestion, Plays a role in toxin degradation, Contributes to maturation of the immune system, Provides a first line of defense (prevents colonization) against microbial pathogens

What happens in bacterial interference?

Competition for receptors or binding sites on host cells, Competition for nutrients; the body is the natural habitat for microflora, Inhibition by metabolic or toxic products, Inhibition by antibiotics or bacteriocins

What is the largest organ in the body?

Skin, 2m^2 in the average adult human

What makes the skin complex?

Prevents loss of moisture, Restricts the entry of pathogens, Varying chemical composition and moisture content

How does the skin protect against pathogens?

it is a natural barrier to microbial colonization

What is the skin microbiome associated with?

the host's hormonal, nervous, and immunological systems

How rich is the skin microbiota?

1M resident bacteria/cm^2, 10^10 microorganisms in the average adult

What are the microbes present in the skin?

Bacteria, archaea, fungi

What is the most common fungus in the skin?

Malassezia

What are the gram-positive bacteria in the skin?

Actinobacteria and Firmicutes

What are the gram-negative bacteria on the skin?

Proteobacteria and Bacteroidetes

What differentiates skin microenvironments?

"Varying temperature, pH, moisture, sebum content, and surface characteristics, Salt and antimicrobial substance in sweat"

What is the dominant bacteria on sebaceous skin?

Propionibacteria

What is the dominant bacteria on moist skin?

Corynebacteria, Staphylococci, Betaproteobacteria

What is the dominant bacteria on dry skin?

Betaproteobacteria

How does the weather influence skin microbiota composition?

"An increase in skin temperature and moisture increases the abundance of the skin microbiota"

How does personal hygiene influence the composition of the skin microbiota?

"Individuals with poor hygiene typically have higher microbial population densities on their skin"

What comprises the skin microbiota of young children?

more varied microbiota, carry more potentially pathogenic microbes (gram-negative bacteria and Streptococcus)

Why is the skin microbiota of children unstable?

because it is not mature yet

What comprises the skin microbiota of post-adolescent young adults?

Propionibacterium and Corynebacterium

How do pets influence the composition of the skin microbiota?

"Adult dog owners have more skin microbes in common with their own dogs than with other dogs"

What is the conjuctiva?

an epithelial layer, it lines the inside of the eyelids and provides a covering to the sclera

How does the conjuctiva protect and lubricate the eye?

through mucus and tears

How does the microflora of the conjuctiva held in check?

by the flow of tears

What is in tears that makes them protective?

They contain antibacterial lysozyme that cleaves glycosidic linkages in the peptidoglycan of the bacterial cell wall which weakens the cell wall and causes cell lysis

What are the predominant microbes in the conjuctiva?

Diphtheroids, S. epidermidis, Nonhemolytic streptococci, Neisseriae, Gram negative bacilli

Why does the upper respiratory tract have microbes?

air borne bacteria continuously enter during breathing

How does the upper respiratory tract manage its microbes?

they are mostly trapped in the mucus of the nasal passages and expelled with nasal secretions

What are the most common microbes in the upper respiratory tract?

Staphylococci, Streptococci, Diphtheroid bacilli, Gram-negative cocci

What are the microbes in the nose microflora?

Corynebacteria, staphylococci (S. epidermidis, S. aureus), streptococci

What are the carriers in the nose microflora?

"Staphylococcus aureus and Streptococcus pneumoniae"

What are the microbes in the pharynx?

streptococci and neisseriae

Why are there microbes in the oral cavity?

they use the surfaces as microhabitats

What type of lifestyle do the microbes of the oral cavity develop?

biofilm lifestyle

Where do the microbes of the oral cavity get nutrients?

saliva, food particles, and cell debris

What is in the saliva that makes it protective?

lysozyme, and lactoperoxidase

How does the lactoperoxidase kill bacteria?

singlet oxygen production

What types of microbes are in the oral cavity microbiota?

At least 750 aerobe and anaerobic species of Bacteria, Methanogenic Archaea, Yeast that are mostly facultative aerobes

What is the dominant bacteria in the saliva?

Firmicutes and gram-positive bacteria

What type of microbiota does the lower respiratory tract have?

transient microbes, not resident

What is the role of the ciliated epithelial cells in the lower respiratory tract?

they push bacteria and other particulate matter toward the upper respiratory tract which is then expelled in saliva and nasal secretions or swallowed

What types of microorganisms are present in the lower respiratory tract?

microorganisms smaller than 10 μm, that can reach the lungs, and bacteria and viruses that cause pneumonia

What types of bacteria are present in the lower respiratory tract?

Prevotella, Veillonella, and Streptococcus

How are bacteria from URT introduced to the LRT?

during normal breathing

What makes the gastrointestinal tract complex?

there are different conditions (e.g. acidity) in each part of the gut

Is the stomach sterile?

even though it is believed to be sterile due to its acidity, it was discovered that there are Helicobacter and other genera of bacteria present

What are the dominant bacteria in the feces?

Bacteriodetes and Firmicutes

When does the colonization of the gut microbiota start?

begins immediately after birth (passage through the mother's vagina)

How does pH influence the diversity of the gut microbiota?

More diverse microorganisms as acidity goes down, the higher the pH, the more microorganisms present

What else influence the microbes present in the gut microbiota?

environmental conditions

What type of archaea is found the stomach and what does it do?

Methanobrevibacter; produces methane