[01.30] General Concepts in Bacteriology 2 (TG16-CG08) (V2) - Alexandra Mendoza.pdf

General Concepts in Bacteriology 2 Module 01: Principles and Perspectives 2 Jhason John J. Cabigon, MD, DPCOM, DPASMAP| Asynchronous RATIONALE..........................................................................................8 ● Invasion: process whereby bacteria, animal parasites, fungi, a...

General Concepts in Bacteriology 2 Module 01: Principles and Perspectives 2 Jhason John J. Cabigon, MD, DPCOM, DPASMAP| Asynchronous RATIONALE..........................................................................................8 ● Invasion: process whereby bacteria, animal parasites, fungi, and viruses enter host cells or tissues and spread in the body ● Microbiota: microbial flora harbored by normal, healthy individuals ● Nonpathogen: a microorganism that does not cause disease ○ May be part of the normal microbiota ● Opportunistic pathogen: an agent capable of causing disease only when the host’s resistance is impaired (i.e. when the patient is “immunocompromised”) ● Pathogen: a microorganism capable of causing disease ● Pathogenicity: ability of an infectious agent to cause disease ● Superantigens: protein toxins that activate the immune system by binding to major histocompatibility complex (MHC) molecules and T-cell receptors (TCR) ○ Stimulate large numbers of T cells to produce massive quantities of cytokines ● Toxigenicity: ability of a microorganism to produce a toxin that contributes to the development of disease ● Virulence: quantitative ability of an agent to cause disease ○ Virulent agents cause disease when introduced into the host in small numbers ○ Involves adherence, persistence, invasion, and toxigenicity LEARNING OBJECTIVES II. INFECTIOUS PROCESS TABLE OF CONTENTS I. GLOSSARY............................................................................................... 1 II. INFECTIOUS PROCESS............................................................................. 1 A. GENERAL PHASES OF INFECTION........................................................1 B. MORE TERMINOLOGIES...................................................................... 2 C. SOURCES OF TRANSMISSION/INFECTION...........................................2 D. TRANSMISSION OF INFECTION........................................................... 3 III. VIRULENCE FACTORS............................................................................. 3 A. ADHERENCE FACTOR.......................................................................... 3 B. INVASION OF HOST CELLS AND TISSUES............................................. 3 C. TOXINS................................................................................................ 3 D. ENZYMES............................................................................................ 4 E. ANTIPHAGOCYTIC FACTORS................................................................ 5 F. INTRACELLULAR PATHOGENICITY........................................................ 5 G. ANTIGENIC HETEROGENEITY.............................................................. 5 H. BACTERIAL BIOFILMS..........................................................................5 I. BACTERIAL PATHOGENESIS: HOW BACTERIA CAUSE DAMAGE........... 5 IV. BACTERIAL MECHANISMS OF GENETIC TRANSFER [VIDEO].................... 7 A. CONJUGATION.................................................................................... 7 B. TRANSFORMATION............................................................................. 7 C. TRANSDUCTION.................................................................................. 7 QUESTIONS................................................................................................ 7 ANSWER KEY.......................................................................................7 1. Discuss the general concepts of bacterial infection, its phases, mechanisms, and factors that contribute to their ability to cause disease 2. Describe bacterial enzymes, toxins, and structure that contribute to infection and disease I. GLOSSARY ● Adherence (adhesion, attachment): process by which bacteria stick to the surfaces of host cells ○ A major initial step in the infection process after bacteria have entered the body ○ The terms adherence, adhesion, and attachment are often used interchangeably ● Carrier: a person or animal with asymptomatic infection that can be transmitted to another susceptible person or animal ● Infection: multiplication of an infectious agent within the body ○ Deemed an infection: multiplication of pathogenic bacteria (e.g., Salmonella species), even if the person is asymptomatic ○ Not considered an infection: multiplication of the bacteria that are part of the normal microbiota of the gastrointestinal tract, skin, and so on YL6:01.30 Take Note! ● This section of the trans was taken from the YouTube video, “Bacterial Infections in Humans” (2019) by Dave Farina ● There are several interchangeable terms that can be used for diseases that spread from host to host ○ Infectious diseases ○ Contagious diseases ○ Communicable diseases ● Generally speaking, infectious diseases can be transmitted at any stage of the infection cycle, it just depends on the microbe ○ Some are more commonly contagious during the incubation period ○ Others, such as Shigella, are more infectious during the invasive period A. GENERAL PHASES OF INFECTION STAGES OF INFECTION ● Incubation period ● Onset of illness ● Invasion period TG16: Cases, Domalanta, Flores, Geolin, Jegillos, Lipana, Lumagbas, Macalintal, Mata, Mendoza, Saz, Sta. Cruz CG08: Andrieux, Banuelos, Fadriquela, Gonsalves, Mallari, Operario, Rengel, Sanchez, Siasoco, Tantay, Zamora 1 ● Convalescent period ○ These few remaining bacteria are the most resistant of the bunch ○ If you continue the full course of treatment, you take care of all of them and recover ○ If you stop taking the drug mid-course, those resistant bugs repopulate, stronger and more resistant than ever ▸ Also, that particular drug won’t work next time TYPES OF INFECTION ● Infection is characterized by progression of symptoms Acute Inflammation Figure 1. Four General Stages of Bacterial Infections in Humans Incubation Period ● Begins from the moment that a microbe is introduced to a susceptible host to the moment that symptoms begin to appear ● Incubation time depends on the pathogen ○ It can range from a few days, such as in the common cold, to a few weeks or months, and up to several years such as in leprosy ● Length of incubation depends on factors such as: ○ Health of the host ○ Growth rate of the pathogen ○ Number of infectious cells the host was exposed to ● During the incubation period, the pathogen is multiplying at the port of entry, but it has not caused enough damage to cause symptoms yet Onset of Illness ● Immediately follows the incubation period ● In the early phases of some illnesses, you might experience the prodromal phase ○ Prodromal phase is where you feel ‘weak and achy’ before the full-blown illness comes on Invasion Period ● The pathogen reaches peak toxicity, multiplying and establishing itself within the tissues ● Common symptoms depend on the infection, but generally include include: ○ Fever ○ Cough ○ Rash ○ Diarrhea ○ Swelling ○ Pain ○ Loss of muscle control ● The period of invasion can vary drastically, depending on the pathogen Convalescent Period ● The immune system fights off the infection ● Convalescent period means a phase of recovery ● Some patients may stop taking antibiotics during this phase because they feel better, however, this is not a good idea ○ As your body is recovering and fighting an illness, there are still pathogenic bacteria present ▸ albeit at low levels, not enough to cause noticeable disease YL6:01.30 General Concepts in Bacteriology 2 ● Symptoms develop quickly and clear quickly ● Infected person develops an immunity to reinfection from the same pathogen ● E.g., Strep throat Chronic Inflammation ● Symptoms come on slowly and can last from months to years ● E.g., Tuberculosis Latent Infection ● Illness never completely goes away ● E.g., Syphilis, tuberculosis, typhoid fever ○ In these cases, a person might experience acute or chronic onset of symptoms, followed by a period of convalescence, then latency ● Latency: a period where there is no sign of disease at all ○ The disease can come back from dormancy at any time ○ The pathogenic microbe might linger in host tissues without causing disease, waiting to act when immunity is low Carriers ● Individuals that carry infectious diseases in their tissues for months or years ● Carriers spread infectious diseases them to other people without suffering any signs or symptoms themselves B. MORE TERMINOLOGIES ● Localized Infection: Infections can be localized to a particular region in the body ○ E.g., ear infection, boil ● Systemic infection: Infects the entire body all at once ○ E.g., chicken pox, measles ● Bacteremia: Implies that bacteria are circulating in the blood ○ The suffix -emia means ‘in the blood’ ● Toxemia: Toxins are circulating in the blood ● Septicemia: Term for large numbers of microbes multiplying and circulating in the blood ● Sequelae: Some diseases cause sequelae, which means long-term or permanent damage C. SOURCES OF TRANSMISSION/INFECTION ● Some bacteria that commonly cause disease in humans exist primarily in animals and incidentally infect humans ○ Salmonella and Campylobacter species typically infect animals and are transmitted in food products to humans 2 ● Other bacteria produce infection in humans that is inadvertent or a mistake in the normal life cycle of the organism ○ Means that the organisms have not adapted to humans and the disease they produce may be severe ○ E.g. Y. pestis (plague) has a well-established life cycle in rodents and rodent fleas ▸ Transmission by the fleas to humans is inadvertent ○ E.g. Clostridium species are ubiquitous in the environment and are transmitted to humans by: ▸ Ingestion ⎻ Clostridium perfringens gastroenteritis ⎻ Clostridium botulinum (botulism) ▸ When wounds are contaminated by soil ⎻ C. perfringens (gas gangrene) ⎻ Clostridium tetani (tetanus) RESERVOIR ● Infectious microbes need to have a reservoir ○ Reservoir: the natural habitat of a pathogen ○ Reservoirs can be anything from humans or animal carriers, to plants, soil, or water ● Example: an animal harbors a pathogen ○ Pathogen can be transmitted either directly from the animal to a human through: ▸ A vector such as a flea, tick, or mosquito ▸ A vehicle such as water ○ Some pathogens such as the causative agent of tuberculosis can live for a long time in non-living reservoirs, such as soil, air, water ▸ They may infect any unsuspecting human that comes in contact ● Asymptomatic carriers are living reservoirs [Case] Typhoid Mary ● One of the most notorious asymptomatic carriers of all time who unknowingly spread Salmonella typhi around New York in the early 1900s ZOONOSIS ● Refers to infectious agents that are indigenous to animals, but can be naturally transmitted to humans ○ In these cases, the human is called a “dead end host”, because they cannot transfer the infection along. ● Zoonotic diseases account for almost 70% of emerging infectious diseases around the world, especially for those who regularly work or live with animals Active Recall Box 1. T/F. During the incubation period, a pathogen is multiplying and is capable of causing symptoms already. 2. T/F. All infectious microbes need to have a reservoir. Answers: 1F, 2F D. TRANSMISSION OF INFECTION ● The most frequent portals of entry of pathogenic bacteria into the body are the sites where mucous membranes meet with the skin ○ Respiratory (upper and lower airways) YL6:01.30 General Concepts in Bacteriology 2 ○ Gastrointestinal (primarily mouth) ○ Genital ○ Urinary tracts ● Other frequent sites of entry ○ Abnormal areas of mucous membranes and skin ▸ E.g. cuts, burns, and other injuries ● Many bacteria are transmitted from one person to another on hands ● Clinical manifestations of diseases (e.g., diarrhea, cough, and genital discharge) produced by microorganisms often promote transmission of the agents TYPES OF DISEASE TRANSMISSION Vertical Transmission ● Transmission of a pathogen from parent to offspring ○ Either through the placenta, milk, ovum, or sperm Horizontal Transmission ● The spread of a pathogen from one infected person to another ○ Direct: skin contact, bite, injection, exposure ○ Indirect: from an infected surface Oral-Fecal Route ● Feces is ingested ○ Due to poor hand washing during food preparation or touching a contaminated surface and then the mouth III. VIRULENCE FACTORS A. ADHERENCE FACTOR FIMBRIAE/PILI ● Structures that extend from the bacterial cell surface ● Help mediate adherence of the bacteria to host cell surfaces LIPOTEICHOIC ACID AND PROTEIN F ● Cause adherence of the streptococci to buccal epithelial cells ○ Adherence is mediated by fibronectin, which acts as the host cell receptor molecule M PROTEIN ● Acts as an antiphagocytic molecule ● Major virulence factor B. INVASION OF HOST CELLS AND TISSUES ● Bacteria produce virulence factors that cause the host cells to engulf (ingest) the bacteria ● When inside the host cell, bacteria may remain enclosed in a vacuole composed of the host cell membrane ○ Vacuole membrane may also be dissolved and bacteria may be dispersed in the cytoplasm ● Some bacteria multiply within host cells, but other bacteria do not C. TOXINS ● Endotoxin: present in the outer membrane of Gram-negative rods ● Exotoxin: secreted toxins ○ Diphtheria toxin ▸ From diphtheriae ▸ Producing diphtheria 3 ○ Tetanospasmin ▸ From tetani ▸ Degrades synaptobrevin, a protein required for docking of neurotransmitter vesicles on the presynaptic membrane ⎻ Release of the inhibitory glycine and GABA is blocked ⎻ Motor neurons are not inhibited ⎻ Results in spastic paralysis ○ Botulinum toxin ▸ From botulinum ▸ Inhibits the release of acetylcholine at the synapse ▸ Results in lack of muscle contraction and flaccid paralysis ○ Alpha toxin and Theta toxin ▸ From perfringens ▸ Necrotizing and hemolytic effects producing gas gangrene ▸ Alpha toxin ⎻ Lecithinase that damages cell membranes by splitting lecithin into phosphorylcholine and diglyceride ○ Toxic shock syndrome toxin-1/TSST-1 ▸ From aureus ▸ A superantigen that causes toxic shock syndrome ▸ Characterized by shock, high fever, and a diffuse red rash that later desquamates ▸ Multiple other organ systems are involved ○ Pyrogenic exotoxins A and C ▸ From group A β-hemolytic streptococci ▸ Superantigens that act in a manner similar to TSST-1 ○ Enterotoxins ▸ From aureus, V. cholerae, others ▸ Associated with diarrheal disease and food poisoning Table 1. Exotoxins and their Bacterial Source Endotoxin Bacterial Source Diphtheria toxin Corynebacterium diphtheriae Tetanospasmin Clostridium tetani Botulinum toxin Clostridium botulinum Alpha toxin and Theta toxin Clostridium perfringens Toxic shock syndrome toxin-1/TSST-1 Staphylococcus aureus Pyrogenic exotoxins A and C Group A β-hemolytic Streptococcus Enterotoxins Staphylococcus aureus Vibrio cholerae Others Table 2. Major Differences Between Exotoxins and Endotoxins Exotoxins ● Excreted by living cell ● High concentrations in liquid medium YL6:01.30 Endotoxins ● Integral part of the cell wall of Gram-negative bacteria General Concepts in Bacteriology 2 ● Released on bacterial death and in part during growth ● May not need to be released to have biologic activity ● Produced by both Gram-positive and Gram-negative bacteria ● Found only in Gram-negative bacteria ● Polypeptides with a molecular weight of 10,000–900,000 ● Lipopolysaccharide complexes ● Lipid A portion probably responsible for toxicity ● Relatively unstable ● Toxicity often destroyed rapidly by heating at temperatures above 60°C ● Relatively stable ● Withstand heating at temperatures above 60°C for hours without loss of toxicity ● Highly antigenic ● Stimulate formation of high-titer antitoxin ● Antitoxin neutralizes toxin ● Weakly immunogenic ● Antibodies are antitoxic and protective ● Relationship between antibody titers ● Protection from disease is less clear than with exotoxins ● Converted to antigenic nontoxic toxoids by formalin, acid, heat ● Toxoids are used to immunize (e.g., tetanus toxoid) ● Not converted to toxoids ● Highly toxic ● Fatal to animals in microgram quantities or less ● Moderately toxic ● Fatal for animals in tens to hundreds of micrograms ● Usually bind to specific receptors on cells ● Specific receptors not found on cells ● Usually do not produce fever in host ● Usually produce fever in the host by release of interleukin-1 and other mediators ● Frequently controlled by extrachromosomal genes (e.g. plasmids) ● Synthesis directed by chromosomal genes D. ENZYMES ● Tissue-degrading Enzymes ○ Collagenase ▸ From perfringens ▸ Degrades collagen - major protein of fibrous connective tissue ▸ Promotes spread of infection in tissue ○ Coagulase 4 ▸ From aureus ▸ Works in conjunction with blood factors to coagulate plasma ▸ Contributes to the formation of fibrin walls around staphylococcal lesions ⎻ Protects from phagocytosis or from destruction within phagocytic cells ○ Hyaluronidases ▸ From staphylococci, streptococci, and anaerobes ▸ Hydrolyze hyaluronic acid, a constituent of the ground substance of connective tissue ▸ Aid in their spread through tissues ○ Streptokinase/fibrinolysin ▸ From streptococci ▸ Dissolve coagulated plasma ▸ Aids in the rapid spread through tissues ▸ Used in the treatment of acute myocardial infarction to dissolve fibrin clots ○ Hemolysin ▸ A cytolysin that dissolves red blood cells ○ Leukocidins ▸ A cytolysin that kills tissue cells or leukocytes ● IgA1 Proteases ○ Splits and inactivate IgA activity ○ Important among: ▸ N. gonorrhoeae ▸ N. meningitidis ▸ Haemophilus influenzae ▸ S. pneumoniae E. ANTIPHAGOCYTIC FACTORS Table 3. Antiphagocytic Factors Type Example Surface protein A (aureus) Binds to the Fc portion of IgG Capsules S. pneumoniae, H. influenzae, N. meningitides, K. pneumoniae, E. coli, group B streptococci M protein S. pyogenes or group A streptococci Pili N. gonorrhoeae (gonococci) F. INTRACELLULAR PATHOGENICITY ● Some bacteria live and grow in the hostile environment within polymorphonuclear cells, macrophages, or monocytes ● Not digested by lysozymes G. ANTIGENIC HETEROGENEITY ● Some have the ability to make frequent shifts in the antigenic form of their surface structures H. BACTERIAL BIOFILMS ● A slimy coat on solid surfaces ● Aggregates of interactive bacteria attached to a solid surface or to each other ● Encased in an exopolysaccharide matrix YL6:01.30 General Concepts in Bacteriology 2 I. BACTERIAL PATHOGENESIS: HOW BACTERIA CAUSE DAMAGE? Take Note! ● This section of the trans was taken from the YouTube video, “Bacterial Pathogenesis: How Bacteria Cause Damage” (2019) by Dave Farina ● The human body contains a variety of environmental niches that allow bacteria to grow and thrive ○ Moisture ○ Warmth ○ Food ○ Protection ● Over time, bacteria have gained or lost genetic traits that allow them to adapt and better survive ○ May allow them to invade a particular environment better ○ Survive longer in a particular niche ○ More effectively break down food ○ Evade detection by the immune system ● Bacteria might develop enhanced virulence factors, allowing them to cause disease more effectively ● Virulent bacteria: grow and thrive at the expense of their host ○ Release toxins that can travel through the blood, causing life-threatening disease ○ Directly degrade tissues or trigger aggressive cascades within the immune system ○ Often, the symptoms we experience are caused by an excessive inflammatory or immune system response triggered by the infection, and not necessarily the bacteria itself ASSESSING DEGREE OF DISEASE ● Degree of disease caused by bacteria depends on multiple factors ○ Importance of affected tissue/organ ▸ Severity of infection of CNS vs left pinky toe ○ Strain of bacteria and inoculum size ▸ Shigella only requires 200 bacteria (small inoculum size) to cause GI distress ▸ Salmonella requires at least a million or more to cause a serious infection ○ Status of host ▸ Immunocompromised individuals might only need less Salmonella to get sick HOW BACTERIA CAUSE DESTRUCTION Entry ● The body has natural defense mechanisms ○ Skin ▸ Prevents microorganisms from invading ○ Tears ▸ Contain enzymes that attack bacteria ○ Airways ▸ Filter out harmful particles ○ Mucous Membranes ▸ Coated with secretions that fight off microorganisms ○ Earwax ○ Stomach acid 5 ● However, some microbes bypass these defenses ○ Salmonella, Vibrio, Bacillus cereus, and Shigella can enter the body through ingestion ▸ Results from stale food or from poor hand washing ○ Streptococcus, Mycobacterium, or Legionella enter through inhalation ▸ Sneeze of sick person ▸ Infected aerosol particles in the air ○ Clostridium tetani (causative agent of tetanus) ▸ Through trauma or a wound ● Other portals of entry: ○ Mosquito bite ○ Needlestick injuries ○ Sexual transmission Adhesion ● Bacteria have many mechanisms to both adhere to surfaces within the body and colonize ○ Colonize: to establish a microbial presence and multiply (once contact is made) Figure 2. (left) Fimbriae/Pili, (right) Adhesin on Neisseria gonorrhoeae ● Prokaryotic cells have short, hair-like structures called fimbriae or pili ○ To attach to various surfaces in nature ● Some have adhesins on the tips of pili that specifically evolved to allow them to bind tightly to cells in your body ○ Ex. Pili of Neisseria gonorrhoeae bind specifically to oligosaccharide receptors on epithelial cells ● Formation of biofilms is another bacterial adaptation that promotes colonization ○ Biofilms: collectives of one or more types of microorganisms ○ Within a biofilm, bacteria form sticky webs of polysaccharides that bind bacterial cells together into a community, providing protection from antibiotics or host defenses ○ Bacteria like Pseudomonas aeruginosa can sense when enough bacteria are present and triggers biofilm formation via quorum sensing ○ Biofilms are particularly common on catheters, dental plaque, or implanted surgical devices such as pacemakers BACTERIAL DAMAGE (TOXINS) ● For some bacteria, natural by-products of their growth can cause tissue destruction ○ Anaerobic bacteria in the gut ▸ Those that don’t require oxygen for growth can produce toxins, enzymes, gas, and acid which destroy the surrounding tissue (e.g., Staphylococci or Streptococci) ○ Bacteria have momentum with enzymes facilitating the spread of disease YL6:01.30 General Concepts in Bacteriology 2 ○ Bacteria can produce harmful substances called toxins: ▸ Meant to attack other bacteria in the vicinity or damage the host they’ve settled in ▸ Toxins can cause degradation/lysis of cells ▸ Trigger destructive immune responses ▸ For some diseases, symptoms can be fully attributed to toxin production with damage occurring right where the infection is ▸ In other cases, the toxin may travel through the bloodstream causing symptoms somewhere else in the body ⎻ Ex. Tetanus or Staphylococci-associated infections Gram-Positive Bacteria ● Components that make up the bacterial cell wall can set off a powerful chain reaction within the immune system ● During an infection of gram-positive bacteria, the peptidoglycan, and its products can stimulate a fever or inflammation with devastating effects on the body Endotoxin Proteins by Gram-Negative Bacteria ● Lipopolysaccharide produced by gram-negative bacteria is an endotoxin ● Low doses: can activate the immune system or protective responses (e.g., fever) ● Higher doses: can trigger extremely high fever, shock, or skin lesions which can be deadly Exotoxic Bacteria ● Can be produced by either gram-positive or gram-negative bacteria ● Proteins in this category: ○ Cause cytolysis ▸ Causes the cell to burst from osmotic pressure ○ Receptor-binding proteins ▸ Either cause cell death or change in function all together ● Often encoded on a plasmid or a phage Superantigens ● Activate the immune system to a life-threatening degree ○ Causes toxic shock syndrome BACTERIAL MECHANISMS TO ESCAPE BODILY DEFENSE ● Bacteria have developed multiple mechanisms to escape our host defenses ○ Especially in the case of long-term infections ● Alter surface proteins ○ To evade detection ○ E.g., Neisseria gonorrhoeae ● Physically hide within cells in the body ● Inactivate antibacterial defenses ● One of the most powerful virulence factors that some bacteria have are slime layers called capsules ○ Capsules can mimic the surface of the host cell ▸ Shields the bacteria from typical immune responses ● Other bacteria create makeshift shields within the site of infection ○ E.g., Staphylococcus aureus ▸ Forms a barrier using coagulase SUMMARY ● Bacteria have a wide array of tricks 6 ○ Some may express one virulence mechanism, while others might express several in tandem ○ All together, these mechanisms are what trigger disease symptoms Active Recall Box 3. ___________ is the multiplication of an infectious agent within the body. A. Pathogenicity B. Virulence C. Infection D. Toxigenicity 4. Which of the following can protect bacteria from typical immune responses by mimicking the surface of the host cell? A. Pili B. Capsule C. Biofilms D. Adhesions Answers: 3C, 4B IV. BACTERIAL MECHANISMS OF GENETIC TRANSFER [VIDEO] A. CONJUGATION ● Involves cell-to-cell contact ● Mediated by a particular kind of circular DNA called a plasmid, which replicated independently of the chromosome ○ Many plasmids carry genes that confer resistance to antimicrobials ● When two cells are in close proximity to one another a hollow bridgelike structure known as a pilus forms between two cells ○ Produced by donor cells ○ This allows a copy of the plasmid as it is duplicated to be transferred from one bacterium to another ○ This enables susceptible bacteria to acquire resistance to a particular antimicrobial agent after gene transfer B. TRANSFORMATION ● During this process, genes are transferred from one bacterium to another as “naked” DNA ○ Direct DNA uptake ● Species-specific ● Requires competence factors ● When cells die and break apart, DNA can be released into the surrounding environment ● Other bacteria in close proximity can scavenge this free-floating DNA and incorporate it into their own DNA ○ This DNA may contain advantageous genes, such as antimicrobial resistant genes and benefit the recipient cell C. TRANSDUCTION ● In this process, bacterial DNA is transferred from one bacterium to another inside a virus that infects bacteria ● These viruses are called bacteriophages or phage ● When a phage takes over a bacterium, it essentially takes over the bacteria’s genetic processes to produce more phage YL6:01.30 General Concepts in Bacteriology 2 ● During this process bacterial DNA may be inadvertently be incorporated into into the new phage DNA ● Upon bacterial death and lysis, or breaking apart, these new phage go on to infect other bacteria ○ This brings along genes from the previously infected bacterium QUICK REVIEW QUESTIONS 1. The following terms refers to the process by which bacteria stick to the surface of host cells EXCEPT A. Adhesion B. Adherence C. Attachment D. Agglutination 2. Zoonotic diseases account for 10% of emerging infectious diseases around the world. These are transmitted from plants to humans. A. The first statement is true B. The second statement is true C. Both statements are true D. Both statements are false 3. Toxigenicity is the ability of an infectious agent to cause disease. Pathogenicity refers to the ability of a microorganism to produce a toxin that contributes to the development of disease. A. The first statement is true B. The second statement is true C. Both statements are true D. Both statements are false 4. A toxin that specifically causes cytolysis and may cause either cell death or change in function. A. Endotoxin proteins B. Exotoxin proteins C. Either A or B D. NOTA 5. This phase in bacterial infections is characterized by the prodromal phase. A. Incubation period B. Onset of illness C. Period of invasion D. Convalescent period 6. A type of disease transmission that spreads from one infected person to another. A. Vertical transmission B. Horizontal transmission C. Oral-fecal route D. Genetic transmission 7. An exotoxin produced by Staphylococcus sp. which produces shock, high fever, and a diffuse red rash that desquamates over time. A. Botulinum toxin B. Alpha and theta toxin C. TSST-1 D. Tetanospasmin 7 8. T/F: Endotoxins can be found in both gram-positive and gram-negative bacteria A. True B. False 9. Hyaluronidase is a tissue-degrading enzyme that hydrolyzes hyaluronic acid. What bacteria is capable of producing this enzyme? A. Staphylococci B. Streptococci C. Anaerobes D. AOTA 10. A process in the genetic transfer mechanism of bacteria that involves DNA transfer from one bacterium to another inside a virus that infects bacteria A. Conjugation B. Transformation C. Transduction ANSWER KEY 1D, 2D, 3D, 4B, 5B, 6B, 7C, 8B, 9D, 10C RATIONALE 1. D. Agglutination - Adhesion, adherence, and attachment are all used interchangeably to refer to the process of bacteria sticking onto host cells 2. D. Both statements are false - Zoonotic diseases account for 70% of emerging infectious diseases around the world. These are transmitted from animals to humans 3. D. Both statements are false - Toxigenicity is the ability of a microorganism to produce a toxin that contributes to the development of disease. Pathogenicity is the ability of an infectious agent to cause disease. 4. B. Exotoxin proteins - Exotoxin proteins can be produced by either gram-positive or gram-negative bacteria. These toxins cause cytolysis which causes the cell to burst from osmotic pressure. These toxins are also receptor-binding proteins which can cause either cell death or change in function all together. 5. B. Onset of illness - Onset of illness immediately follows the incubation period. In the early phases there is the existence of a prodromal phase, wherein the infected individual feels ‘weak and achy’ before the full-blown illness is initiated. 6. B. Horizontal transmission - Horizontal transmission is the spread of a pathogen from one infected person to another. Vertical transmission is the transmission of a pathogen from parent to offspring. Oral-fecal route refers to ingestion of the pathogen. 7. C. TSST-1 - Toxic shock syndrome toxin-1/TSST-1 is an exotoxin produced by Staphylococcus aureus. It is a superantigen that causes toxic shock syndrome and is characterized by shock, high fever, and a diffuse red rash. 8. B. False - Endotoxins are found only in gram-negative bacteria. 9. D. AOTA - Hyaluronidase can be produced by either staphylococcus, streptococci, and anaerobes. 10. C. Transduction - Conjunction involves cell-to-cell contact. Transformation involves direct DNA uptake, and requires competence factors. Transduction involves bacterial DNA being transferred from one bacterium to another inside a virus that infects bacteria. YL6:01.30 General Concepts in Bacteriology 2 REFERENCES REQUIRED ● 💻 : Farina, D. (2019, December 31). Bacterial Infection in Humans [Video]. YouTube. https://www.youtube.com/watch?v=FeFKAl9KyMg&t=10s&ab_chan nel=ProfessorDaveExplains : Farina, D. (2019, December 17). Bacterial Pathogenesis: How ● Bacteria Cause Damage [Video]. YouTube. https://www.youtube.com/watch?v=qZCanCxo0tI : Boyd, A. (2011, October 26). Genetic Transfer [Video]. Youtube. ● https://www.youtube.com/watch?v=Fq0YSTyJlpk ● Riedel, S., Morse, S.A., Mietzner, T., Miller, S. (2019). Jawetz, Melnick, & Adelberg’s medical microbiology (28th ed.). McGraw-Hill Education. 💻 💻 📖 SUPPLEMENTARY ● 📄 ASMPH Batch 2026. 01.28b: General Concepts in Bacteriology by Cabigon, MD, DPCOM, DPASMAP Concerns and Feedback form: http://bit.ly/YL6CFF2027 How’s My Transing? form: https://bit.ly/2027YL6HMT Mid-Semester Evaluation form: https://bit.ly/2027YL6MidSem End-of-Semester Evaluation form: https://bit.ly/2027YL6EndofSem Errata Points Trackers: https://bit.ly/YL62027EPT YL6 TransMap: https://bit.ly/2027YL6TransMap FREEDOM SPACE 8