Podcast
Questions and Answers
During which phase of bacterial growth does cell death significantly outpace cell growth?
During which phase of bacterial growth does cell death significantly outpace cell growth?
- Stationary phase
- Decline/death phase (correct)
- Log phase
- Lag phase
Which bacterial counting method involves spreading a fixed volume from a serial dilution onto the surface of a medium?
Which bacterial counting method involves spreading a fixed volume from a serial dilution onto the surface of a medium?
- Direct smear
- Pour plate method
- Counting chamber
- Spread plate method (correct)
In the pour plate method, where do bacteria grow?
In the pour plate method, where do bacteria grow?
- Attached to the petri dish
- Both the surface and within the agar (correct)
- Exclusively on the surface of the agar
- Exclusively within the agar
What is the focus of bacterial taxonomy?
What is the focus of bacterial taxonomy?
Which of the following methods uses a calibrated slide in order to count bacterial cells in a fixed volume?
Which of the following methods uses a calibrated slide in order to count bacterial cells in a fixed volume?
Which type of pathogen requires infecting a host to multiply and transmit?
Which type of pathogen requires infecting a host to multiply and transmit?
A microorganism that can cause disease only under specific conditions, such as a suppressed immune system, is best described as what type of pathogen?
A microorganism that can cause disease only under specific conditions, such as a suppressed immune system, is best described as what type of pathogen?
Which of the following factors relates most directly to the pathogen's role in bacterial pathogenesis?
Which of the following factors relates most directly to the pathogen's role in bacterial pathogenesis?
Which of the following best describes 'pathogenesis'?
Which of the following best describes 'pathogenesis'?
Which of the following is the broadest term?
Which of the following is the broadest term?
What is a key attribute that distinguishes a facultative pathogen from an obligate pathogen?
What is a key attribute that distinguishes a facultative pathogen from an obligate pathogen?
Which factor related to the host is considered as an element of bacterial pathogenesis?
Which factor related to the host is considered as an element of bacterial pathogenesis?
What distinguishes an infectious disease from a general disease?
What distinguishes an infectious disease from a general disease?
What is the primary role of autoinducers in bacterial communication?
What is the primary role of autoinducers in bacterial communication?
Which characteristic is most important for bacteria within a biofilm?
Which characteristic is most important for bacteria within a biofilm?
What is the main outcome of quorum sensing in bacteria?
What is the main outcome of quorum sensing in bacteria?
How are virulence factors typically transferred between bacteria?
How are virulence factors typically transferred between bacteria?
What is the defining characteristic of bacterial transformation?
What is the defining characteristic of bacterial transformation?
During bacterial transduction, what acts as the vector for transferring genetic material?
During bacterial transduction, what acts as the vector for transferring genetic material?
What physical structure facilitates genetic material transfer during bacterial conjugation?
What physical structure facilitates genetic material transfer during bacterial conjugation?
Which of these phases describes a period of bacterial adaptation to a new environment, characterized by little to no cell division?
Which of these phases describes a period of bacterial adaptation to a new environment, characterized by little to no cell division?
How does a bacteria acquire antimicrobial resistance?
How does a bacteria acquire antimicrobial resistance?
A microbiologist counts bacterial colonies on a petri dish, observing both surface and embedded colonies within the agar medium. Which enumeration technique is being employed?
A microbiologist counts bacterial colonies on a petri dish, observing both surface and embedded colonies within the agar medium. Which enumeration technique is being employed?
Which characteristic is least useful for classifying bacteria under the polyphasic taxonomy approach?
Which characteristic is least useful for classifying bacteria under the polyphasic taxonomy approach?
Which type of pathogen exhibits the characteristic of being able to multiply and transmit solely through infecting a host and causing disease?
Which type of pathogen exhibits the characteristic of being able to multiply and transmit solely through infecting a host and causing disease?
In the infectious disease complex, which component is most directly related to the virulence, resistance mechanisms, and survival capabilities of a microorganism?
In the infectious disease complex, which component is most directly related to the virulence, resistance mechanisms, and survival capabilities of a microorganism?
Under what circumstances does an infection not always lead to disease?
Under what circumstances does an infection not always lead to disease?
A dog presents with flu-like symptoms, and urinalysis reveals spirochetes, leading to a Leptospira suspicion. Which virulence factor is most likely being expressed by this organism?
A dog presents with flu-like symptoms, and urinalysis reveals spirochetes, leading to a Leptospira suspicion. Which virulence factor is most likely being expressed by this organism?
During Gram staining, what would be the likely outcome if the alcohol step is omitted?
During Gram staining, what would be the likely outcome if the alcohol step is omitted?
Which bacterial type lacks a cell wall but contains sterols in its cytoplasmic membrane?
Which bacterial type lacks a cell wall but contains sterols in its cytoplasmic membrane?
What is the initial and critical step in biofilm formation?
What is the initial and critical step in biofilm formation?
What is the primary mechanism by which superantigens induce a cytokine storm?
What is the primary mechanism by which superantigens induce a cytokine storm?
What is an example of a virulence factor?
What is an example of a virulence factor?
If a bacteria loses its capsule, what is the most likely result?
If a bacteria loses its capsule, what is the most likely result?
Which bacteria is most likely to cause pneumonia in pigs?
Which bacteria is most likely to cause pneumonia in pigs?
What is the primary function of sterols in the plasma membrane of Mycoplasma?
What is the primary function of sterols in the plasma membrane of Mycoplasma?
Which component of the bacterial cell wall is primarily responsible for the antigenicity of bacteria?
Which component of the bacterial cell wall is primarily responsible for the antigenicity of bacteria?
What is the function of iodine in the Gram-staining procedure?
What is the function of iodine in the Gram-staining procedure?
What property of mycobacteria cell walls prevents decolorization with acid alcohol during acid-fast staining?
What property of mycobacteria cell walls prevents decolorization with acid alcohol during acid-fast staining?
Which of the following is NOT a function of the bacterial plasma membrane?
Which of the following is NOT a function of the bacterial plasma membrane?
What is the purpose of applying heat in the Ziehl-Neelsen staining procedure?
What is the purpose of applying heat in the Ziehl-Neelsen staining procedure?
If a bacterium is Gram-negative, what color will it appear after Gram staining?
If a bacterium is Gram-negative, what color will it appear after Gram staining?
What cellular structure differentiates mycobacteria from other bacteria that are not acid-fast?
What cellular structure differentiates mycobacteria from other bacteria that are not acid-fast?
Which bacterial shape is characterized by a flexible, spiral-shaped morphology?
Which bacterial shape is characterized by a flexible, spiral-shaped morphology?
Which of the following describes bacterial reproduction?
Which of the following describes bacterial reproduction?
What is the term for the time required for a bacterial cell to divide into two daughter cells?
What is the term for the time required for a bacterial cell to divide into two daughter cells?
In which phase of the bacterial growth curve does the rate of cell division approximately equal the rate of cell death?
In which phase of the bacterial growth curve does the rate of cell division approximately equal the rate of cell death?
What is the primary metabolic process used by obligate aerobes?
What is the primary metabolic process used by obligate aerobes?
Which gaseous requirement describes bacteria that grow best at lower oxygen levels than atmospheric levels?
Which gaseous requirement describes bacteria that grow best at lower oxygen levels than atmospheric levels?
What is the optimal pH range for the growth of most pathogenic bacteria?
What is the optimal pH range for the growth of most pathogenic bacteria?
What is the term for bacteria that require an environment enriched with carbon dioxide for optimal growth?
What is the term for bacteria that require an environment enriched with carbon dioxide for optimal growth?
Which of the following temperature ranges is most conducive to the growth of the majority of pathogenic bacteria affecting mammals?
Which of the following temperature ranges is most conducive to the growth of the majority of pathogenic bacteria affecting mammals?
During which phase of the bacterial growth is cell metabolism most active, preparing the cells for division?
During which phase of the bacterial growth is cell metabolism most active, preparing the cells for division?
What physiological responses are characteristic of Toxic Shock Syndrome (TSS)?
What physiological responses are characteristic of Toxic Shock Syndrome (TSS)?
Which of the following is the most precise definition of quorum sensing in bacteria?
Which of the following is the most precise definition of quorum sensing in bacteria?
How do bacteria primarily 'communicate' during quorum sensing?
How do bacteria primarily 'communicate' during quorum sensing?
What is a critical outcome of quorum sensing in bacteria?
What is a critical outcome of quorum sensing in bacteria?
What triggers the alteration of gene expression in quorum sensing?
What triggers the alteration of gene expression in quorum sensing?
What is the relationship between quorum sensing and antimicrobial resistance (AMR)?
What is the relationship between quorum sensing and antimicrobial resistance (AMR)?
In Toxic Shock Syndrome, even with receptors activated, there are no antibodies targeting which entities?
In Toxic Shock Syndrome, even with receptors activated, there are no antibodies targeting which entities?
What is the function of autoinducers?
What is the function of autoinducers?
Which method is NOT part of polyphasic taxonomy for classifying bacteria?
Which method is NOT part of polyphasic taxonomy for classifying bacteria?
What type of symbiotic relationship describes mutualism?
What type of symbiotic relationship describes mutualism?
Which of the following best describes symbionts?
Which of the following best describes symbionts?
Which property is NOT typically analyzed in the classification of bacteria?
Which property is NOT typically analyzed in the classification of bacteria?
Which statement regarding beneficial and harmful bacteria is correct?
Which statement regarding beneficial and harmful bacteria is correct?
Which type of bacteria is characterized by a thick peptidoglycan layer and (lipo)teichoic acids?
Which type of bacteria is characterized by a thick peptidoglycan layer and (lipo)teichoic acids?
Which statement accurately describes Gram-negative bacteria?
Which statement accurately describes Gram-negative bacteria?
Which bacterial cell structure enhances the ability to evade phagocytosis?
Which bacterial cell structure enhances the ability to evade phagocytosis?
Which type of bacteria is identified using the Ziehl-Neelsen (acid-fast) staining method?
Which type of bacteria is identified using the Ziehl-Neelsen (acid-fast) staining method?
During which phase of bacterial growth do cell death and slow multiplication reach a balance?
During which phase of bacterial growth do cell death and slow multiplication reach a balance?
What type of genetic material is located in the nucleoid region of bacteria?
What type of genetic material is located in the nucleoid region of bacteria?
Which structure in bacteria is primarily responsible for adhesion to surfaces?
Which structure in bacteria is primarily responsible for adhesion to surfaces?
Which type of cell structure could provide resistance to environmental stresses such as desiccation?
Which type of cell structure could provide resistance to environmental stresses such as desiccation?
Which phase is characterized by a rapid increase in bacterial population?
Which phase is characterized by a rapid increase in bacterial population?
Which method primarily involves counting visible masses of bacteria on the surface and within a medium?
Which method primarily involves counting visible masses of bacteria on the surface and within a medium?
Which classification method does not fit within the polyphasic taxonomy framework?
Which classification method does not fit within the polyphasic taxonomy framework?
What type of pathogen must infect a host to multiply and cause disease?
What type of pathogen must infect a host to multiply and cause disease?
Which aspect relates specifically to the pathogen in the infectious disease complex?
Which aspect relates specifically to the pathogen in the infectious disease complex?
Which statement is true regarding infection and disease?
Which statement is true regarding infection and disease?
Which of the following best describes a facultative pathogen?
Which of the following best describes a facultative pathogen?
In polyphasic taxonomy, which characteristic is a common basis for bacterial classification?
In polyphasic taxonomy, which characteristic is a common basis for bacterial classification?
Why are exotoxins generally easier to create vaccines against compared to endotoxins?
Why are exotoxins generally easier to create vaccines against compared to endotoxins?
What is the primary mechanism through which quorum sensing regulates gene expression in bacteria?
What is the primary mechanism through which quorum sensing regulates gene expression in bacteria?
A patient is exhibiting symptoms indicative of septic shock, including multiple-organ system failure, high fever, and a sharp drop in blood pressure. Which virulence factor is most likely responsible for these symptoms?
A patient is exhibiting symptoms indicative of septic shock, including multiple-organ system failure, high fever, and a sharp drop in blood pressure. Which virulence factor is most likely responsible for these symptoms?
What is the purpose of communication for the purpose of making biofilm?
What is the purpose of communication for the purpose of making biofilm?
What is the best explanation of quorum sensing?
What is the best explanation of quorum sensing?
During which phase of bacterial growth are resources depleted and waste products accumulated, leading to a balance between cell division and cell death?
During which phase of bacterial growth are resources depleted and waste products accumulated, leading to a balance between cell division and cell death?
Which method is used to enumerate bacteria when colonies are observed both on the surface and within the medium?
Which method is used to enumerate bacteria when colonies are observed both on the surface and within the medium?
Which of the following characteristics is least relevant when classifying bacteria using polyphasic taxonomy?
Which of the following characteristics is least relevant when classifying bacteria using polyphasic taxonomy?
What is the defining characteristic of an obligate pathogen?
What is the defining characteristic of an obligate pathogen?
According to the infectious disease complex, which component is most directly related to the virulence and survival capabilities of a microorganism?
According to the infectious disease complex, which component is most directly related to the virulence and survival capabilities of a microorganism?
Which of the following is NOT part of the infectious disease complex?
Which of the following is NOT part of the infectious disease complex?
Why is it false that an infection always causes disease?
Why is it false that an infection always causes disease?
What mechanism allows virulent gene factors to transfer to other bacteria using a viral vector?
What mechanism allows virulent gene factors to transfer to other bacteria using a viral vector?
Which process involves direct contact between bacteria for the temporary transfer of genetic material?
Which process involves direct contact between bacteria for the temporary transfer of genetic material?
Which of the following bacterial structures is most directly associated with evading phagocytosis by immune cells?
Which of the following bacterial structures is most directly associated with evading phagocytosis by immune cells?
Within the process of infection, what is the step immediately following a pathogen's entry into a host?
Within the process of infection, what is the step immediately following a pathogen's entry into a host?
Which of the following is NOT typically considered a bacterial virulence factor?
Which of the following is NOT typically considered a bacterial virulence factor?
What is the key characteristic of Gram-positive bacteria related to their cell wall structure?
What is the key characteristic of Gram-positive bacteria related to their cell wall structure?
Why doesn't an infection always lead to the host becoming a carrier of the disease?
Why doesn't an infection always lead to the host becoming a carrier of the disease?
If a dog is suspected of having a Leptospira infection, what virulence factor would likely be expressed by the spirochetes?
If a dog is suspected of having a Leptospira infection, what virulence factor would likely be expressed by the spirochetes?
Which of the following statements accurately describes Gram-negative bacteria?
Which of the following statements accurately describes Gram-negative bacteria?
During which phase of bacterial infection is the bacteria multiplying within the host, but the host is not yet capable of transmitting the bacteria to others?
During which phase of bacterial infection is the bacteria multiplying within the host, but the host is not yet capable of transmitting the bacteria to others?
The onset of clinical signs and symptoms in a host most directly indicates the end of which infection phase?
The onset of clinical signs and symptoms in a host most directly indicates the end of which infection phase?
In an environment with very few other bacteria of its kind, how will a bacterium act with regard to autoinducers?
In an environment with very few other bacteria of its kind, how will a bacterium act with regard to autoinducers?
A bacterial population releases autoinducers into its environment. What outcome will only occur when a sufficiently high concentration of the autoinducer is present?
A bacterial population releases autoinducers into its environment. What outcome will only occur when a sufficiently high concentration of the autoinducer is present?
Which type of bacterial virulence factor is most likely responsible for a patient presenting with signs of multiple-organ system failure, shock, and fever?
Which type of bacterial virulence factor is most likely responsible for a patient presenting with signs of multiple-organ system failure, shock, and fever?
What is the role of a viral vector in transferring virulent gene factors between bacteria during bacterial transduction?
What is the role of a viral vector in transferring virulent gene factors between bacteria during bacterial transduction?
What is the crucial requirement for quorum sensing to effectively enable group functioning in bacteria?
What is the crucial requirement for quorum sensing to effectively enable group functioning in bacteria?
What is the primary role of peptidoglycan in bacterial cells?
What is the primary role of peptidoglycan in bacterial cells?
A veterinary professional is evaluating treatment strategies for a bacterial infection in livestock. Given the progression of the disease, which of the following best describes the period when bacteria are actively multiplying within the host, but before any noticeable signs of illness appear?
A veterinary professional is evaluating treatment strategies for a bacterial infection in livestock. Given the progression of the disease, which of the following best describes the period when bacteria are actively multiplying within the host, but before any noticeable signs of illness appear?
Besides endotoxin and exotoxin, which of the following contributes most directly to a bacterium's virulence by enhancing its ability to evade phagocytosis?
Besides endotoxin and exotoxin, which of the following contributes most directly to a bacterium's virulence by enhancing its ability to evade phagocytosis?
How does biofilm formation enhance bacteria's survival and virulence?
How does biofilm formation enhance bacteria's survival and virulence?
During which mechanism does a bacteria release autoinducers in an environment with very little other bacteria of its type? Select the MOST accurate answer after reading the options:
During which mechanism does a bacteria release autoinducers in an environment with very little other bacteria of its type? Select the MOST accurate answer after reading the options:
What is the purpose of acid-fast staining techniques such as Ziehl-Neelsen?
What is the purpose of acid-fast staining techniques such as Ziehl-Neelsen?
Where is genetic material for virulence primarily located in a bacterial cell?
Where is genetic material for virulence primarily located in a bacterial cell?
Which of the following is an important function of biofilm formation?
Which of the following is an important function of biofilm formation?
What structural adaptation allows Leptospira to move effectively through viscous environments?
What structural adaptation allows Leptospira to move effectively through viscous environments?
In Gram staining, if the alcohol step is omitted, what is the likely outcome?
In Gram staining, if the alcohol step is omitted, what is the likely outcome?
Which bacterial genus lacks a cell wall but incorporates sterols into its cytoplasmic membrane for stability?
Which bacterial genus lacks a cell wall but incorporates sterols into its cytoplasmic membrane for stability?
What is the initial and critical step in the formation of a biofilm?
What is the initial and critical step in the formation of a biofilm?
What is the outcome when a bacteria encloses themselves in a thick durable biopolymer matrix?
What is the outcome when a bacteria encloses themselves in a thick durable biopolymer matrix?
What is the mechanism by which superantigens evade MHC complexes?
What is the mechanism by which superantigens evade MHC complexes?
Flashcards
Decline/death phase
Decline/death phase
The stage where cell death exceeds cell growth in bacteria.
Microscopic counting
Microscopic counting
A method where bacteria are counted using a calibrated counting chamber.
Colony Counting
Colony Counting
Methods for measuring bacterial numbers through colony growth.
Spread plate method
Spread plate method
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Bacterial taxonomy
Bacterial taxonomy
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Gram-positive bacteria
Gram-positive bacteria
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Gram-negative bacteria
Gram-negative bacteria
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Nucleoid
Nucleoid
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Capsule function
Capsule function
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Ziehl-Neelsen staining
Ziehl-Neelsen staining
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Stationary phase
Stationary phase
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Mycoplasma
Mycoplasma
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Mycolic acids
Mycolic acids
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Pathogen
Pathogen
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Obligate Pathogen
Obligate Pathogen
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Facultative Pathogen
Facultative Pathogen
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Opportunistic Pathogen
Opportunistic Pathogen
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Accidental Pathogen
Accidental Pathogen
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Disease
Disease
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Infectious Disease
Infectious Disease
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Pathogenesis
Pathogenesis
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Autoinducers
Autoinducers
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Biofilm Formation
Biofilm Formation
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Quorum Sensing
Quorum Sensing
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Virulence Factors
Virulence Factors
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Bacterial Transformation
Bacterial Transformation
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Bacterial Transduction
Bacterial Transduction
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Bacterial Conjugation
Bacterial Conjugation
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Antimicrobial Resistance
Antimicrobial Resistance
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Lag phase
Lag phase
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Logarithmic phase
Logarithmic phase
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Maximal stationary phase
Maximal stationary phase
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Decline phase
Decline phase
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Counting chamber method
Counting chamber method
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Polyphasic taxonomy
Polyphasic taxonomy
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Infection vs. Disease
Infection vs. Disease
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Intracellular Bacteria
Intracellular Bacteria
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Gram Staining Effect
Gram Staining Effect
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Mycoplasma Characteristics
Mycoplasma Characteristics
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Formation of Biofilm Step 1
Formation of Biofilm Step 1
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Superantigen
Superantigen
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Leptospira Virulence Factor
Leptospira Virulence Factor
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Gram Positive vs. Negative
Gram Positive vs. Negative
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Capsule Formation
Capsule Formation
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Symbiont
Symbiont
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Mutualism
Mutualism
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16s rRNA gene
16s rRNA gene
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Beneficial bacteria
Beneficial bacteria
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Bacterium Antigenicity
Bacterium Antigenicity
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Gram Staining Purpose
Gram Staining Purpose
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Acid-fast Staining
Acid-fast Staining
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Mycoplasma Structure
Mycoplasma Structure
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Plasma Membrane Functions
Plasma Membrane Functions
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Peptidoglycan Detection
Peptidoglycan Detection
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Bacterial Growth Curve
Bacterial Growth Curve
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Exponential Phase
Exponential Phase
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Binary Fission
Binary Fission
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Aerobes
Aerobes
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Anaerobes
Anaerobes
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Facultative Anaerobes
Facultative Anaerobes
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Microaerophiles
Microaerophiles
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Generation Time
Generation Time
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Toxic Shock Syndrome
Toxic Shock Syndrome
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Gene Expression Regulation
Gene Expression Regulation
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Biofilm
Biofilm
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Threshold Concentration
Threshold Concentration
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Pheromones in Bacteria
Pheromones in Bacteria
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Cell Density Effect
Cell Density Effect
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Peptidoglycan Layer
Peptidoglycan Layer
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Gram-negative Structure
Gram-negative Structure
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Function of the Capsule
Function of the Capsule
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Nucleoid vs. Plasmid
Nucleoid vs. Plasmid
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Phagocytosis Evasion
Phagocytosis Evasion
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Cell Wall Differences
Cell Wall Differences
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Exotoxin Vaccine
Exotoxin Vaccine
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Endotoxin Symptoms
Endotoxin Symptoms
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Counting visible masses
Counting visible masses
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Capsule
Capsule
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Endotoxin
Endotoxin
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Exotoxin
Exotoxin
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Peptidoglycan
Peptidoglycan
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Inflammatory Response
Inflammatory Response
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Carriers
Carriers
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Incubation Phase
Incubation Phase
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Onset of Symptoms
Onset of Symptoms
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Latent Phase
Latent Phase
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Multiple-Organ Failure
Multiple-Organ Failure
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Endoflagella
Endoflagella
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Intraspecies Signaling
Intraspecies Signaling
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Non-Virulence Factor
Non-Virulence Factor
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Biofilm Formation Step 1
Biofilm Formation Step 1
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Altering Gram Staining
Altering Gram Staining
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Sterols in Bacteria
Sterols in Bacteria
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First Biofilm Step
First Biofilm Step
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Study Notes
Introduction to Microbiology
- TA: Justin Hedlund
- Fall 2023
- Vet Prep RUSVM
- Email: [email protected]
Learning Objectives - VPRP 0906 Bacteriology
-
General Objective: Provide an overview of basic bacteriology, including cell structure, terminology, virulence, taxonomy, and pathogenesis, emerging and zoonotic diseases, and routes to diagnosis, treatment, and prevention.
-
Key Characteristics of Prokaryotes:
- Structural differences from eukaryotes
- Description of bacterial cell wall, plasma membrane, nucleoid, flagella, pili/fimbriae, capsule, and endospores
- Gram stain procedure
- Gram-positive and Gram-negative bacterial morphologies
- Factors for bacterial growth and reproduction
- Phases of bacterial growth curve
-
Bacteria-Specific Terminology & Classification:
- Definitions of symbiont, mutualism, commensalism, pathogen (types), infection, inflammation, disease, pathogenesis, pathogenicity and virulence, plasmid, bacteriophage, quorum sensing, aerobe, facultative anaerobe, microaerophilic, capnophilic, anaerobic, culture media (types), susceptibility break point, MIC, MBC, and antimicrobial.
- Polyphasic taxonomy principle
-
Bacterial Pathogenesis:
- Sequence of events in bacterial pathogenesis
- Characteristics of bacterial virulence factors (toxins, superantigens, biofilm formation)
- Methods of virulence factor transfer (transformation, transduction, and conjugation)
-
Diagnosis of Bacterial Infections:
- Methods to detect the causal agent (direct observation, cultural and biochemical characteristics, serotyping, and molecular techniques)
- Methods to detect host immune response (serology, cell-mediated immunity detection)
-
Treatment of Bacterial Diseases:
- Methods to limit microbial growth
- Sterilization methods
- Antimicrobial classes (5 classes)
- Mode of action (cell wall synthesis inhibitors, protein synthesis, DNA synthesis inhibitors, folic acid synthesis inhibitors)
- Spectrum of activity
- Antimicrobial activity types
- Antimicrobial susceptibility testing and methods
- Antimicrobial resistance (mechanisms)
-
Pathogenic Bacteria:
- Gram-positive cocci (Staphylococcus, Streptococcus)
- Gram-positive rods/bacilli (Listeria monocytogenes, Corynebacterium pseudotuberculosis, Bacillus anthracis, Erysipelothrix rhusiopathiae)
- Gram-positive anaerobes (Clostridium)
- Gram-negative rods/bacilli (Escherichia coli, Salmonella, Brucella, Bordetella bronchiseptica)
- Spirochetes (Leptospira, Borrelia burgdorferi)
- Mycoplasma
- Rickettsiales
-
Bacterial Vaccines:
- Vaccine function
- Vaccination goals (animals targeted)
- Vaccine types and composition/features
- Vaccination failure factors
Key Bacterial Characteristics: Prokaryotes VS. Eukaryotes
- Prokaryotes:
- Unicellular
- No nucleus
- Single circular chromosome
- No cytoskeleton
- Binary fission
- Chemically complex cell wall
- Asexual reproduction
- Eukaryotes (Not Bacteria):
- Nucleus present
- Larger size, or multicellular
- Multiple chromosomes
- Cytoskeleton present
- Mitosis
- Simple cell wall (chemically)
- Meiosis for reproduction
Bacterial Cell Wall
- Functions:
- Protect against mechanical damage and osmotic lysis
- Allows non-selective transport
- Distinguishes species based on pathogenicity and staining properties
- Peptidoglycan: Alternating NAG and NAM subunits crosslinked with short peptides (N-acetylglucosamine, N-acetylmuramic acid)
- Uniqueness to prokaryotic cell wall
- Provides cell wall rigidity
Gram-positive Bacteria Cell Wall
- Multilayered, thick peptidoglycan layer
- Only one plasma membrane
- High resistance to physical disruption and drying
- Highly susceptible to ionic detergents
- Teichoic acids (linked to peptidoglycan)
- Lipoteichoic acids (linked to plasma membrane)
- Crucial for colonization, infection, and immune evasion
- Protect against harmful molecules and environmental stress
- Strongly antigenic
Gram-negative Bacteria Cell Wall
- Thin peptidoglycan layer
- Inner and outer plasma membrane, with periplasmic space
- Low resistance to physical disruption and drying
- Low susceptibility to ionic detergents
- Contains lipopolysaccharides (LPS)
- Lipid A component is the endotoxin, triggering immune responses causing harm to host
- Polysaccharide component causing bacteria antigenicity
Gram-staining Technique
- Differentiates bacteria by chemical and physical properties of their peptidoglycan walls.
- Gram-positive: Purple (absorbs crystal violet dye)
- Gram-negative: Pink (absorbs safranin dye)
Mycobacteria Cell Wall
- Thick waxy, hydrophobic cell wall
- Mycolic acids (prevent decolorization)
- Zeihl-Neelsen staining used for visualization
Exception: Mycoplasma
- Lack cell wall, sterols in plasma membrane for rigidity
Plasma Membrane
- Composed of phospholipids and proteins (no sterols)
- Flexible structure with hydrophobic outside and hydrophilic inside
- Functions: Active transport of nutrients, eliminates waste metabolites, electron transport for bacterial respiration, involved in biosynthesis (DNA, cell wall polymers, lipids)
- Includes mesosomes (in some bacteria)
Genetic Material Locations
- Nucleoid: Region containing the chromosomal DNA
- Single haploid circular chromosome, extensively folded
- Plasmids: Small, circular DNA separate from the chromosome. Often carry virulence genes (e.g., antimicrobial resistance)
Flagella
- Locomotion and motility
- Structurally composed of Filament, hook, and basal body
- Various arrangements (monotrichous, amphitrichous, lophotrichous, peritrichous)
- Endoflagella: corkscrew-like motility (e.g., spirochetes)
Pili/Fimbriae
- Fine, hair-like appendages
- Predominantly in gram-negative bacteria
- Composed of the protein pilin
- Functions: Adhesion to host tissues, and contribute to antigenicity (e.g., E. coli K88, K99)
Capsule
- Also called Glycocalyx
- Extracellular polymeric matrix
- Mostly polysaccharides
- Nutrient reserve, protection against adverse conditions, host cell adherence, interferes with phagocytosis.
Endospores
- Dormant, highly resistant structures
- Cryptobiotic state
- Ensure survival during adverse environmental conditions
- Produced by Clostridium and Bacillus
Endospores: Sporulation Summary
- DNA replicates and elongates
- Septum forms for forespore separation
- Mother cell engulfs forespore (second membrane)
- Mother cell chromosomes disintegrate
- Forespore cortex develops between original and mother cell membranes
- Spore coat formation
- Dormant state and eventually germinate into mature cell.
Bacterial Morphology
- Cocci, streptococci, diplococci, encapsulated diplococci, staphylococci, tetrad
- Bacilli, diplobacilli, pallisades, streptobacilli
- Corkscrew, filamentous, spirochete
- Club rod, helical, and budding/appendaged bacteria
- Visualization by microscopy
Bacterial Metabolism, Phylogeny, and Pathogens
- Bacterial growth curve (enumeration)
- Polyphasic taxonomy
- Metabolic terminology (aerobes, anaerobes, facultative anaerobes, etc.)
- Infectious diseases and bacterial pathogenesis
- Infective disease time periods
Factors Required for Bacterial Growth
- Sources of metabolic energy (aerobic respiration, anaerobic respiration, fermentation, photosynthesis)
- Gaseous requirements (O2, CO2, and other gases)
- Environmental factors (pH, osmotic pressure, light, temperature, nutrients, specific concentrations of ions)
Bacterial Reproduction
- Binary fission
- Chromosomes duplicate, cell elongates, divides, equal inheritance
- Generation time
Bacterial Growth Curve: 4 Phases
- Lag phase: cells grow and metabolize but do not divide
- Logarithmic phase: rapid multiplication
- Stationary phase: balance between cell death and division
- Decline phase: cell death exceeds multiplication
Bacterial growth - specific Factors
- Nutrients (glucose, nitrates, fatty acids)
- pH
- Ionic strength and osmotic pressure
- Temperature
- Gaseous requirement (oxygen, carbon dioxide)
- Osmotic pressure(isotonic, hypotonic, hypertonic)
Methods for Bacterial Counting
- Microscopic counting (direct smear and counting chamber)
- Colony counting (spread plate and pour plate methods)
Phylogeny and Taxonomy
- Bacterial phylogenetic classifications based on 16s rRNA genes
- Polyphasic taxonomy (genotype, phenotype, phylogenetic)
- Identification, nomenclature, classification of organisms – using a variety of factors
- Methods include Morphology and motility, DNA profiling, metabolism, 16s rRNA gene sequencing, whole genome sequencing, and biochemical characteristics
We Live in a Microbial World
- Beneficial bacteria are more prevalent than harmful bacteria.
- Beneficial bacteria (e.g., symbionts, commensals, mutualism, and free-living)
- Harmful bacteria (e.g., obligate, facultative, opportunistic, and accidental pathogens)
Pathogens
- Infectious agents causing disease
- Types: obligate, facultative, opportunistic
Bacterial Pathogenesis
- Host factors (breed, age, sex, genotype, physiology, damage, immunity)
- Pathogen factors (genotype, virulence, resistance, survival, route/vector tropism, inoculation dose)
- Environmental factors (housing, management, hygiene, nutrients, disease control)
- Interaction with host (infection process)
- Infection process steps
An Infection does not Always Result in Disease
- Disease definitions and types
- Infectious diseases (causes and transmission)
- Pathogenesis
- Pathogenicity
- Infection process
- Virulence
Bacterial Pathogenesis: Inflammation
- Harmful stimuli (toxins, immune response)
- Local tissue damage from toxins or immune responses
- Toxaemia (structural or functional alteration)
- Systemic and chronic disease
Iceberg Concept of Disease
- Majority of infections are asymptomatic or subclinical
- Infections without symptoms can still be contagious
- Exposure doesn't guarantee infection or disease
The Consequences of Host-Pathogen Interaction
- Exposure without infection
- Subclinical disease
- Disease with recovery
- Carrier state
- Death or disability (outcome of infection)
Time Periods, Symptoms, and Infectiousness of Pathogens
- Latent period
- Infectious period
- Incubation period
- Relationship between the time periods in infection
Bacterial Virulence Factors
- Bacterial traits enabling pathogenicity
- Extracellular or intracellular colonization
- Obligate intracellular pathogens
- Facultative intracellular pathogens
Some Types of Virulence Factors of Bacteria
- Capsules, flagella, fimbriae
- Toxins (endotoxins, exotoxins, superantigens) – their properties specified
- Biofilm formation
- Quorum sensing
- Intracellular capability (e.g., Listeria)
Exotoxin VS. Endotoxin
- Exotoxins: proteins, heat-labile, highly antigenic, produced during life cycle, highly specific activity in the host (neurotoxin, leukotoxin, enterotoxin, etc.)
- Endotoxins: part of cell wall, heat-stable, weakly antigenic, released when cell dies, non-specific
- Coded locations in DNA (chromosomal or plasmid)
Exotoxins are Superantigens
- Dysfunctional immune system by binding different receptors
- Triggering T-cell proliferation, cytokine release
- No antigenic effects against bacteria
- Multiple-organ system failure, shock, and fever. Specific diseases caused by exotoxins detailed in the text
Quorum Sensing
- Regulation of bacterial gene expression based on cell population density
- Signaling molecules (autoinducers)
- Cell density increases autoinducer concentration, triggering group functioning
Biofilm Formation
- Bacteria adhere to each other and surfaces, forming a thin/thick bipolymer matrix giving nutrients
- Plays a role in persistence infections and plaque formation
- First step: attachment – and the subsequent steps detailed
Quorum sensing - communication
- Bacteria communicate through signaling molecules (autoinducers) when it reaches a critical number in density
- Triggering genes to act as a group rather than individually producing biofilm, sporulation, or antibiotics.
Transfer of Virulence Factors Between Bacteria
- Virulence factors (like resistance, toxins) transferred through plasmids, bacteriophages (capsules, fimbriae).
- Plasmids: small circular DNA within bacteria
- Bacteriophages: viruses infecting and replicating within bacteria, detailing phases of transduction
Bacterial Transformation, Transduction, and Conjugation
- Bacterial transformation: uptake of naked DNA
- Bacterial transduction: viral vector transfer DNA
- Bacterial conjugation: direct contact transfer of DNA
Antimicrobial Resistance
- Innate resistance: Inherited genetic properties
- Acquired resistance
- Clinical use of antibiotics, safe and most appropriate antibiotics
Question Time - Multiple Choice Questions and True/False
- Patient with multiple organ failure shock and fever - the specific cause being detailed
- Gram staining, steps for proper staining - not detailed at this point
Additional Specifics from Questions
- Multiple topics discussed are not fully defined in the given pages
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