Bacteriology MT I

T/F: Phylogenetics studies the relationships of organisms based on evolutionary similarities and differences

True

T/F: Genus and species names are written in bold

False, they may be underlined or italicized

T/F: The 16S ribosomal RNA gene is the standard for classification and identification of bacteria and fungi

False, the 16s ribosomal RNA gene is the standard for bacteria. 18s is used for fungi

T/F: Bacteria and fungi are prokaryotes

False. Bacteria is a prokaryote, fungi is a eukaryote

T/F: Prokaryote cells do not have a membrane-bound nucleus

True

T/F: Gram-stain reaction and colony appearance are examples of bacterial genotype characteristics

False, gram stain reaction is phenotypic

What would be some consequences of the disappearance of microorganisms from the planet?

1. All microbial disease would vanish

2. Most nutrients would stop being made or cycled

3. Waste would accumulate indefinitely

4. Plants would die

5. Ruminants would starve

6. Humans and other life would survive short term, but eventually die

Taxonomy

The science of classifying organisms to construct internationally-shared classification systems

How are names written in a binomial system?

In two parts, the genus name is written first and first letter capitalized. Specific epithet follows and is never capitalized. Always written in italics or underlined.

Why is the 18s rRNA gene used in fungi rather than 16s rRNA gene?

Because they are a prokaryotic organism, they lack 16s

Bacteria

Small, simple prokaryotes that contain no cytoplasmic organelles, lack a membrane-bound nucleus, and have circular or linear chromosomes. Consist of mostly water. Reproduce asexually through binary fission

What is the function of ribosomes?

Protein synthesis

What are some advantages of replication via binary fission?

1. Only one parent is needed to reproduce

2. Daughter cells are clones of the parent

3. Rapid division

4. Many daughter cells produced quickly

Binary Fission

Asexual replication of bacteria

What does the basic structure of bacterial cells involve?

Cell envelope, cytoplasmic structures, surface structures

What does the cell envelope of bacteria include?

Cytoplasmic membrane and cell wall

What do cytoplasmic structures of bacteria include?

Nuclear body, ribosomes, inclusion sites (energy storage) and spores

What do surface structures of bacteria include?

Capsule, flagella, and fimbriae or pili

What are the three basic shapes of bacteria?

Spherical/Coccus

Bacilli/Rod

Spiral

Lipopolysaccharides are found in what bacteria only?

Gram-negative

The rigidity of bacteria is contributed to by what layer?

The peptidoglycan layer

What are the functions of the cell envelope of bacteria?

Structural support and protection

Selective barrier and transport

Virulence and immune evasion

Cell wall enzymes

What color will gram positive bacteria stain?

Blue/purple

What color will gram negative bacteria stain?

Pink/red

Flagellum

Filamentous appendages that allow bacteria to move in liquid environments. Mainly in gram-negative bacteria. Chemotaxis

Chemotaxis

Movement towards a chemical attractant, such as food

Pilus

Thread-like appendages, smaller than flagella. Mainly in gram negatives. Two types serve different functions

What are the two basic types of pili?

Short attachment (fimbriae) and long conjugation

Encapsulated bacteria produce what kinds of colonies?

Mucoid

Microbiota

Community of living microorganisms in a particular environment

Microbiome

Entire ecosystem, involving microorganisms, their genetic material, metabolites, and surrounding environment

Endospores

Highly resistant, dormant structures formed inside certain bacteria (i.e. Bacillus and Clostridium)

Dormant

Metabolically inactive

Long-lived

Can survive for years (or centuries)

T/F: The structure of the bacterial cell envelope determines whether the organism is gram positive or negative

True, the peptidoglycan layer determines stain uptake

T/F: Gram-positive bacteria have a thin layer of peptidoglycan in their cell wall and an extra outer membrane

False

T/F: Gram-negative bacterial cell wall resists decolorization with acid alcohol

False

T/F: The outermost layer of the gram-positive cell envelope is called LPS

False, it is present in the gram-negative cell envelope

T/F: Bacteria use flagella and pili for movement in different environments

True

T/F: Microbiome is a monomicrobial community

False

T/F: Endospores can germinate into vegetative cells when conditions are favorable

True

T/F: Bacterial capsules facilitate host immune recognition and phagocytic killing

False, they have protective properties

Describe the differences between prokaryotic and eukaryotic cells

Prokaryotic cells have a circular/linear genome and lack a membrane-bound nucleus, reproduce through binary fission

Eukaryotic cells have a membrane-bound nucleus, mitochondria and endoplasmic reticulum

What is the difference between core genes and accessory genes in bacteria?

Core genes are essential for survival, while accessory genes are adaptive

What are some benefits of studying bacterial structure and function?

Developing therapeutic techniques and vaccines, studying pathogenicity

T/F: Dual intracellular/extracellular pathogens use multiple virulence mechanisms to survive and grow inside or outside host cells

True

T/F: Attachment to and colonization of host surfaces are key steps in bacterial infection

True

T/F: Host immune cells PRRs recognize bacterial PAMPs

True

T/F: Gram-positive cell LPS can cause endotoxemia with massive cytokine release resulting in sepsis and septic shock

False, gram-negative

T/F: Bacteria are not able to share genes with different bacterial species

False, there are three methods of horizontal transfer

T/F: Plasmids, integrons, and transposons are mobile genetic elements

True

T/F: Horizontal gene transfer allows bacteria to evolve and adapt rapidly

True

Infection

Establishment of a microorganism in a host

Pathogen

An organism that can cause disease

Virulence

The degree of pathogenicity of a pathogen

Pathogenicity

The ability of a microorganism to cause disease

Extracellular pathogen

Does not invade cells, proliferates in extracellular environment. May cause disease by secreting toxins

Facultative Intracellular pathogen

Dual intra/extracellular. Uses multiple strategies and virulence factors to survive and grow inside or outside of hosts

Obligate intracellular pathogen

Cannot live outside the host cell, requires its energy. Cannot be grown on artificial media, require cell culture, embryonated egg culture

Bacteremia

Presence of viable bacteria in the blood

Septicemia

The presence of viable bacteria in the blood

Sepsis

Systemic inflammatory response syndrome

Septic shock

A severe complication of sepsis that can include very low blood pressure and multiple organ failure

Primary pathogen

Can cause disease upon infection in healthy hosts. More virulent

Opportunistic pathogen

Doesn't normally harm host. Causes disease when host virulence is low. Less virulent

Obligate pathogen

Cannot survive for long outside of host

Are Koch's postulates always applicable?

Not always, cannot always prove a casual relationship between a microbe and disease

T/F: Failure to satisfy all of Koch's postulates always disproves a connection of evidence for a cause-and effect relationship

False, not always

What are the key steps in the bacterial infection and disease process?

1. Entry into the host

2. Attachment (adhesion) and colonization

3. Spread into host tissue

4. Damage to and survival in host

5. Transmission to new hosts or survival off host

What are the three mechanisms contributing to bacterial infection immunity?

Cell-mediated, innate, and antibody-mediated immunity

T/F: Bacteria have unique pathogen-associated molecular patterns (PAMPs)

True

What pathogens use a "stealthy strategy" to escape recognition by the innate immunity and to evade intracellular killing

Facultative Intracellular Pathogens (FIPs)

Quorum sensing

A process of cell-cell communication that allows bacteria to share information about cell density and adjust gene expression accordingly

What are ways that a bacterium may cause disease

Invasiveness (destruction of tissue), toxigenicity, stimulating overwhelming host immune responses, combinations

Bacteria virulence factors

Intracellular: toxins, enzyme, etc

Extracellular: Fimbriae, pili, etc

Capsule

Well organized, thick, gelatinous outer covering that lies outside the bacterial cell wall

Slime layer

A loose, unorganized, easily removable glycocalyx outside of the bacterial cell wall

Biofilm

Structured community of bacteria enclosed in a self-produced slime-like matrix attached to a surface

Stuart Medium

Aerobic, aerotolerant, fastidious organisms

Cary-Blair Agar

Fecal samples, suspect Salmonella

Amies medium with charcoal

Charcoal neutralizes toxins. Taylorella equigenitalias. Brachyspira, Campylobacter, Moraxellla

Amies medium without charcoal

For the isolation of Mycoplasma and Ureaplasma

Anaerobic Transport Medium (ATM)

Thioglycollate broth medium

Is a dry swab or transport medium swab preferred for culture?

Transport medium swab

What are the five steps of specimen submission

Stage, site, collect, label, store and ship

T/F: Samples in formalin, alcohol, EDTA or heparin are appropriate for culture

False

T/F: Red top tubes with no additive are acceptable for culture

True

Which samples are aerobic in a culture test

Urine, ear, skin, feces

Which samples are anaerobic for a culture test?

Septic abdomen, feces, wound

Poor Sampling Technique

Complicate patient management by providing irrelevant or even misleading results

T/F: Clinical specimen should be collected at an early stage of infection

True

T/F

Amies medium with charcoal is preferred for sampling pink eye

True

T/F: Urine sample can be stored at room temperature until shipping to the diagnostic lab

False

T/F: Double guarded swab is used for uterine sampling

True

T/F: Ear swab is typically submitted for anaerobic culture

False

T/F: A single blood sample is good enough to detect bacteria

False

T/F: A wound sample can yield both aerobic and anaerobic pathogens

True

The preferred method of urine collection is?

Cystocentesis

Besides diagnosis and antibiotic sensitivity confirmation, reason for submitting specimens to a diagnostic lab includes?

Surveillance, monitoring, research

T/F: While sampling, gloves are optional

False