Infectious Diseases Quiz

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Questions and Answers

What is the definition of etiology in the context of infectious diseases?

The study of disease processes

The symptoms experienced by a patient

The cause of a disease (correct)

The presence of bacteria in the bloodstream

Which phase of disease occurs immediately after the incubation period?

Illness phase (correct)

Chronic phase

Convalescence

Latency period

What is a significant risk factor for reactivation of a disease?

High levels of hydration

Increased immune system strength

Immediate medical intervention

Weak immune response (correct)

In the context of sepsis, what does bacteremia refer to?

The presence of bacteria in the blood Signup and view all the answers

According to Hugo Schottmüller, what is a necessary condition for diagnosing sepsis?

Bacteremia Signup and view all the answers

What term describes the period of recuperation and recovery following the illness phase?

Convalescence Signup and view all the answers

What key factor is crucial in determining patient outcomes from sepsis?

The host response to the infection Signup and view all the answers

What distinguishes infection from disease?

Infection refers to microbial invasions that may not cause symptoms Signup and view all the answers

Which of the following diseases is NOT commonly contracted via the skin?

Cholera Signup and view all the answers

What is a common disease contracted through the conjunctiva?

Herpes ocularis Signup and view all the answers

Which factor does NOT contribute to the establishment of disease?

Severity of symptoms at first infection Signup and view all the answers

What common disease can be contracted parenterally?

Hepatitis Signup and view all the answers

Which pathogen is uniquely affected by its portal of entry, as described in the content?

Salmonella typhi Signup and view all the answers

Which of the following is NOT a sexually transmitted disease listed?

Shigellosis Signup and view all the answers

How do microorganisms typically enter the body through parenteral routes?

Through the bloodstream Signup and view all the answers

Which of the following correctly identifies the primary portal of entry for HIV?

Mucous membranes of the genitourinary tract Signup and view all the answers

What characterizes commensalism in host-pathogen relationships?

Neither organism benefits or is harmed. Signup and view all the answers

Which of the following is an example of mutualism?

E.coli in the gut Signup and view all the answers

What defines a pathogen's pathogenicity?

The susceptibility of the host and virulence of the pathogen. Signup and view all the answers

Opportunistic pathogens typically do not cause disease except under which circumstances?

Compromised immune system or abnormal environment. Signup and view all the answers

Which portal of entry is most frequently used by pathogens?

Mucous membranes of the respiratory tract Signup and view all the answers

How do microbes typically enter the gastrointestinal tract?

Through contaminated food and water. Signup and view all the answers

What is required for a microbe to cause disease after entering a host?

Evading host defenses and damaging host tissues. Signup and view all the answers

Which pathogen is often associated with secondary infections after the flu due to a compromised environment?

Pneumocystis carinii Signup and view all the answers

What does LD50 refer to in microbiology?

The number of microbes in a dose that kill 50% of the organisms infected Signup and view all the answers

Which statement accurately describes ID50?

It denotes the number of microbes required to cause disease in 50% of infected organisms. Signup and view all the answers

What is the role of pili in the pathogenic process?

To bind to host glycoproteins and aid in adherence Signup and view all the answers

In the context of pathogenicity, what does the term 'virulence factor' refer to?

Substances produced by pathogens that help establish and maintain disease Signup and view all the answers

During bacterial invasion, which requirement must be met to succeed?

The pathogen must obtain essential nutrients and protect itself from host defenses Signup and view all the answers

What type of damage is primarily caused by byproducts of bacterial growth?

Tissue destruction and the release of degradative enzymes Signup and view all the answers

Which of the following is NOT a type of virulence factor?

Nutrient absorption mechanisms Signup and view all the answers

Fibronectin Binding Proteins function primarily as what type of virulence factor?

Adhesion factors that bind to specific tissue receptors Signup and view all the answers

Which mechanism allows bacteria to be 'not seen' by immune system cells?

Encapsulation Signup and view all the answers

What is a significant change in an antigen called that can stimulate antibody production?

Antigenic shift Signup and view all the answers

Which bacterial characteristic is primarily composed of polysaccharides and helps prevent phagocytosis?

Capsule Signup and view all the answers

Leukocidins are involved in which of the following immune evasion strategies?

Destruction of phagocyte Signup and view all the answers

What is the outcome of antigenic mimicry in pathogens?

Evasion of antibody recognition Signup and view all the answers

The process by which phagolysosome fusion is inhibited primarily aids in which type of microbial strategy?

Intracellular replication Signup and view all the answers

What do hemolysins primarily target in the host body?

Red blood cells Signup and view all the answers

Which strategy is NOT a defense mechanism employed by microbes to evade the immune response?

Phagocyte recruitment Signup and view all the answers

What is the primary function of coagulase in pathogenic bacteria?

Protects bacteria from phagocytosis Signup and view all the answers

Which enzyme is responsible for the shedding of blood clots and facilitating bacteremia?

Streptokinase Signup and view all the answers

What type of bacteria typically produces hyaluronidase?

Both Streptococci and Staphylococci Signup and view all the answers

Which of the following conditions is most associated with collagenase activity during infection?

Gas Gangrene Signup and view all the answers

What effect does the necrotizing factor have on tissue cells?

Causes necrosis Signup and view all the answers

Alpha hemolytic streptococci are characterized by their ability to:

Cause incomplete lysis of red blood cells Signup and view all the answers

What is a common characteristic of beta hemolytic streptococci?

They cause complete lysis of red blood cells Signup and view all the answers

Which statement about hyaluronic acid is incorrect?

It stimulates blood clot formation. Signup and view all the answers

Study Notes

Host-Pathogen Relationships

Host-pathogen relationships involve the interaction between a host and a pathogen.
Commensalism: one benefits, the other is unaffected. An example is Corynebacterium in the eyes.
Mutualism: both benefit. An example is E. coli in the gut.
Parasitism: one benefits, the other is harmed. An example is any pathogen.
Pathogenicity depends on host susceptibility and pathogen virulence.

Chapter Overview

Infectious diseases require basic concepts.
Host-pathogen relationships determine portals of entry and virulence factors.
Virulence factors facilitate disease establishment and maintenance.

Definitions

Pathology: study of disease.
Etiology: the cause of a disease.
Pathogenesis: the development of a disease.
Infection: colonization of a microbe.
Disease: illness.
Virulence: degree of pathogenicity.
Bacteremia: presence of bacteria in the blood.
Sepsis/Septicemia: body's inflammatory response to an infection.

Infection and Disease

Infection: invasion by parasitic microbes. Infection doesn't always cause disease.
HIV infection can lead to AIDS.
Disease is a change in health, damage to the host.

Phases of Disease

Incubation: the time between pathogen introduction and symptom onset (variable).
Illness: experience of disease signs and symptoms.
Convalescence: recovery period, potentially with pathogen spread.

Types of Disease

Acute: organism disappears after illness, generally with immunity.
Chronic: illness persists or recurs.
Latent: illness may recur, if immunity weakens, after a period of no symptoms.

Sepsis

Sepsis is a severe systemic inflammatory response to microbial invasion.
The host response is as important as the pathogen's virulence.
Bacteremia is critical for diagnosis, however the host's response is the key driver of outcome.

Microbiome

Microbiome: the community of microorganisms routinely found on a healthy individual.
Humans have more microbes than stars.
Most of the microbiome is located in the GI tract.
The microbiome has significant influence on health and disease.

Opportunistic Pathogens

Opportunistic pathogens usually do not cause disease.
However, in certain circumstances, normal flora can cause disease. (In the wrong environment, such as a compromised immune system).
E. coli in the urinary tract is an example.
Weakened immunity, such as in AIDS, or conditions like pneumonia can cause opportunistic infections.

Pathogenic Microorganisms

For disease to occur, a microbe must gain access and evade defenses.
Possible entry points are mucous membranes, skin, and parenteral(punctures etc).
The pathogen must then damage tissues.

Portals of Entry

Respiratory tract: Microbes enter via inhaled moisture or dust particles, causing common cold, flu, tuberculosis, and whooping cough.
Gastrointestinal tract: Microbes enter via contaminated food or water, causing salmonellosis, shigellosis, botulism, and cholera.
Genitourinary tract: Sexually transmitted diseases (STDs) like gonorrhea, syphilis, chlamydia, and HIV.
Conjunctiva: Common diseases include chlamydia and herpes ocularis.
Skin: Some microbes enter through skin openings or damage, causing staphylococcal infections and mycosis.
Parenteral: microbes enter through punctures, injections, bites, scratches, or surgery, causing diseases like hepatitis and HIV.

Factors That Determine Disease Establishment

Pathogen entry does not always result in disease.
Preferred portal of entry is important.
Virulence factors (like toxins, or capsule) are essential considerations.

Steps for Pathogen Infection

Step 1: Adherence: pathogens use pili or other structures to attach to host cells.
Step 2: Invasion/Colonization: Pathogens multiply, gain nutrients, and evade host defenses (especially the immune system).
Step 3: Cause Damage: Pathogens destroy tissues through toxins (such as exotoxins and endotoxins) and enzymes.

Virulence Factors

Virulence factors are substances that promote and maintain disease.
Types include adhesion factors, evasion of immune responses, degradative enzymes, and toxins.

Adhesion Factors

Pili (fimbriae) are short, rigid, numerous protrusions.
Adhesins bind to host receptors on tissues.

Evading Immune Response

Encapsulation: prevents phagocytosis (by macrophages etc).
Antigenic mimicry: pathogens resemble host cells.
Antigenic shift: change in pathogen proteins (antigens) that causes antibody ineffectiveness.
Inhibition of phagolysosome fusion: inhibits the pathogen from being destroyed.
Immunoglobulin protease production
Destruction of phagocyte
Inhibition of chemotaxis
Resistance to lysosomal enzymes
Intracellular replication

Degradative Enzymes

Leukocidins: kill white blood cells, preventing phagocytosis, (and preventing the host's defense mechanisms from functioning appropriately).
Hemolysins: cause lysis (breakdown) of red blood cells.
Coagulase: causes blood clotting, protecting bacteria from phagocytes.
Kinases: dissolve blood clots, enabling pathogen spread.
Hyaluronidase: breaks down hyaluronic acid, enabling pathogen spread through tissues.
Collagenase: breaks down collagen, enabling pathogen spread through tissues.
Necrotizing factors: cause tissue death.

Toxins

Toxins are poisonous substances.
Exotoxins are secreted, heat labile, and may or may not be able to produce an antitoxin.
Endotoxins (part of cell wall) are similar among species, cause similar symptoms, and are difficult to neutralize.
Toxemia: toxins in the blood stream causing disease.

Classification of Exotoxins

Leukotoxins: target white blood cells.
Cytotoxins: damage host cells (eg., kill).
Neurotoxins: target nervous system.
Enterotoxins: target the digestive system.
Hepatotoxins: target the liver.
Cardiotoxins: target the heart.

Leukotoxins: Superantigens

Invoke very strong immune responses.
Affect T cells, causing severe symptoms

Cytotoxins: Membrane Disrupting Toxins

Disrupt host plasma membranes (via impacting phospholipids or protein structures).
Examples include toxins that target RBCs or phagocytes.

Neurotoxins: A-B Toxins

Toxins of Clostridium botulinum and Clostridium tetani affect neuromuscular transmission; including blocking/stimulating nerve activity.

###Endotoxins

Component of the outer membrane of Gram-negative bacteria.
Cause similar symptoms in various species.
Not easily deactivated.
Induce excessive/destructive host immune responses.
Induce TNF release from macrophages.

Endotoxin Symptoms

Pyrogenic (fever) response: Interleukin-1 prompts prostaglandin release from the hypothalamus.
Leukopenia followed by leukocytosis – white blood cell abnormalities
Activation of complement: complement proteins are involved in host immune defenses.
Thrombocytopenia: abnormal decrease in platelets.
Disseminated Intravascular Coagulation (DIC): widespread clotting.
Shock and death.

Host Susceptibility/Resistance

Factors influencing the host's susceptibility/resistance to infection include age, pre-existing conditions, diet, hygiene, and behavior.
Stress factors such as weather, can also affect the susceptibility to pathogens.

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Description

Test your knowledge on key concepts of infectious diseases including etiology, phases of disease, and patient outcomes. This quiz covers essential terms and risks related to infection and sepsis. Perfect for students and professionals in the health sciences field.