C8 - Host Microorganisms Interactions (Part 1) Flashcards by Mark James Mateo

→ growth and multiplication of microorganisms that cause damage to the host

Infection

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→bodily invasion of pathogenic microorganisms that reproduce, multiply and then cause disease through local injury, toxin secretion or An-Ab reaction to the host

Infection

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→caused by microorganism from the microbiota of the host

Autogenous Infection

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→ result of medical treatment or procedure

Iatrogenic infection

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→affects immunocompromised host

Opportunistic Infection

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→hospital-acquired infection

Nosocomal infection

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Types of Infections

a. Autogenous
b. Iatrogenic
c. Opportunistic
d. Nosocomal

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4 common types of INFECTION

UTI
Lung Infection (Pneumonia)
Surgical site Infection
Blood stream Infection

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Predisposing factors

a. Wide variety of microbes in the hospital environment
b. Immunocompromised patient
c. Chain of transmission (direct or Indirect)

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Chain of Transmission EXAMPLES

✓ Health worker to patient
✓ Patient to patient
✓ Use of fomites(catheters, needles, dressings, beds)
✓ Airborne transmission
✓ Vector-borne

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Airborne transmission (TB & Pertussis)

TB: < 5um, Pertussis: > 5um

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cornerstone of modern infection control program

Handwashing

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TYPES OF INFECTION ACCORDING TO HOST DISTRIBUTION

Local Infection
Focal Infection
Systemic Infection

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signs and symptoms are confined in one area; wounds, boils, abscesses

Local Infection

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starts as a focal infection before spreading to other parts of the body

Focal Infection

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spread throughout the body through the blood or lymph

Systemic Infection

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presence of bacteria in blood; highest concentration of bacteria in blood occurs before the fever spikes

Bacteremia

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active multiplication of bacteria in blood

Septicemia

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pus-producing organisms repeatedly invade the bloodstream and become localized at different parts of the body

Pyremia

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presence of toxins in the blood

Toxemia

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Classification of Disease According to Occurrence

Sporadic
Endemic
Epidemic
Outbreak
Pandemic

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disease that occurs occasionally

Sporadic

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a disease constantly present at some rate of occurrence in a particular location

Endemic

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a larger than normal number of diseased or
infected individuals in a particular location

Epidemic

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a larger than normal number of diseased or infected individuals that occurs over a relatively short period

Outbreak

an epidemic that spans the world

Pandemic

a person who carries the etiologic agent but shows no apparent signs or symptoms of infection or disease

Carrier

harbors the microorganism temporarily for a few days or weeks

Causal/Acute/Transient Carrier

remain infected for a relatively long time, sometimes throughout its entire life (Typhoid Bacillus)

Chronic Carrier

recovered from infection but continuous to harbour larger numbers of the pathogen

Convalescent Carrier

overt clinical case of the disease

Active carrier

PHASES OF INFECTIOUS DISEASES

- Incubation Period - Prodromal Period - Clinical or Illness Period - Decline Period - Convalescence or the Period of Recovery

time between the exposure to a pathogenic organism and the onset of symptoms

Incubation Period

appearance of signs and symptoms period

Prodromal Period

peak of characteristic signs and symptoms

Clinical or Illness Period

signs and symptoms begin to subside as the host’s condition improves

Decline Period

host is recuperating towards full recovery

Convalescence or the Period of Recovery

a microorganism responsible for causing infection or infectious disease

Causative/Etiologic Agent

organism capable of producing disease

Pathogen

a quantitative measure of the degree of pathogenecity of a particular microorganism

Virulence

microorganism that does not cause disease; may be part of the normal flora

Nonpathogenic

an agent capable of causing disease only when the host's resistance is impaired (PAE, Stenotrophomonas maltophilia)

Opportunistic pathogen

means by which etiologic agents are brought in contact with the human host (e.g. infected blood, contaminated water, insect bite)

Mode of Transmission

a non-living entity that is contaminated with the etiologic agent and as such is the mode of transmission for that agent

Vehicle/Fomite

a living entity (animal, insect, or plant) that transmits the etiologic agent

Vector

an animal or plant that harbors or nourishes another organism

Host

an organism which is dependent on another organism for food and shelter

Parasite

any type of epidemiologic investigation that involves data collection for characterizing circumstances surrounding the incidence or prevalence of a particular disease or infection

Surveillance

the state of disease and its associated effects on the host

Morbidity

death resulting from disease

Mortality

laboratory-based characterization of etiologic agents designed to establish their relatedness to one another during a particular outbreak or epidemic

Strain typing

origin of the etiologic agent or location from which they disseminate (e.g., water, food, insects, animals, other humans)

Reservoir

the etiologic agent responsible for an epidemic or outbreak originates from a single source or reservoir

Common Source

association of two organisms living in close proximity

Symbiosis

refers to a mutually beneficial relationship between two species

Mutualism

a relationship wherein the parasite derives benefits from the host without causing injury or harm to the host

Commensalism

a relationship whereby one organism derives benefits at the expense of another

Parasitism

ability of the organism to produce disease

Pathogenicity

large groups of genes that are associated with pathogenicity and are located on the bacterial chromosome

Pathogenicity Island

the ability of the organism to enter host tissues, multiply, and spread faster

Invasiveness

ability of the organism to produce toxins

Toxigenicity

non-poisonous forms of toxins which can be used for vaccination

Toxoid

Toxoid Preparation

✓ By aging ✓ By exposure to heat ✓ By exposure to 50% alcohol, formaldehyde, and dilute acids

General Stages of Microbial-Host Interaction

Physical encounter between host and microorganism → Microorganism colonization of host surface(s) → Microorganism entry, invasion, and dissemination → Outcome

microorganisms that are commonly found on or in body sites of healthy persons

Normal, Usual, or Indigenous Flora

microorganisms that colonize an area for months or years

Resident Microbial Flora

microorganisms that are present at a site temporarily represent

Transient Flora

Microorganism's presence depends on:

✓physiologic factors of temperature ✓moisture ✓presence of certain nutrients and inhibitory substances

Microbial Flora ROLE!!!

➢Provide a first line of defense against microbial pathogens ➢Assist in digestion and absorption of nutrients; also synthesis of Vitamin K ➢Play a role in toxin-degradation ➢Contribute to maturation of the immune system

How does MICROBIAL FLORA provides first line of defense?

✓competition for receptors or binding sites on host cells ✓competition for nutrients ✓mutual inhibition by metabolic or toxic products ✓mutual inhibition by antibiotic materials or bacteriocins

Different Body Site of Microbial Flora

a. Usual Flora of the Skin b. Usual Flora of the Mouth c. Usual Flora of the Respiratory Tract d. Usual Flora of the GIT e. Usual Flora of the Genitourinary Tract

**_____________ in vagina is a part of the normal flora but are important colonizers

Escherichia coli

ability of a microbe to produce disease in a susceptible individual

Pathogenicity

→are organisms recognized to cause disease in healthy immunocompetent individuals

True pathogens

Example of True Pathogens

Yersinia pestis Bacillus anthracis

→cause disease if the host is immunocompromised

Opportunistic pathogens

Example of Opportunistic Pathogen

E. coli

Conditions Compromising Host Defenses

Foreign bodies Alcoholism Burns Hematoproliferative disorders Cystic fibrosis Immunosuppression

Examples of Foreign Bodies that can compromise host defenses

catheters, shunts, prosthetic heart valves

Foreign bodies - Organisms

Staphylococcus epidermidis Propionibacterium acnes Aspergillus spp. Candida albicans Viridans streptococci Serratia marcescens Pseudomonas aeruginosa

Alcoholism - Organisms

Streptococcus pneumoniae Klebsiella pneumoniae

Burns - Organisms

Pseudomonas aeruginosa

Hematoproliferative disorders - Organisms

Cryptococcus neoformans Varicella-zoster virus

Cystic fibrosis - Organisms

Pseudomonas aeruginosa Burkholderia cepacia

Immunosuppression (drugs, congenital disease) - Organisms

Candida albicans Pneumocystis jirovecii (carinii) Herpes simplex virus Aspergillus Diphtheroids Cytomegalovirus Staphylococcus spp. Pseudomonas spp.

→relative ability of a microorganism to cause disease or the degree of pathogenicity →measured by the numbers of microorganisms necessary to cause infection in the host

Virulence

Microbial Virulence Factors

a. inhibiting phagocytosis b. Facilitating adhesion to host cells or tissues c. enhancing intracellular survival after phagocytosis d. damaging tissue through the e. production of toxins and extracellular enzymes

→highly virulent →mask the cell surface structures that are recognized by receptors on the surface of the phagocytic cell →inhibits the activation of complement by masking structures to which complement proteins bind

Capsule

Example of Microorganisms that uses Capsule to resist Phagocytosis

S. pneumoniae H. influenzae N. meningitidis K. pneumoniae S. typhi P. aeruginosa B. anthracis Y. pestis

→interfering with the binding of the host’s antibodies to the surface of the organism → binds to the Fc portion of IgG preventing opsonization and phagocytosis by turning the antibody around on the surface

Protein A

Protein A is found in the cell wall of

Staphylococcus aureus

CELL WALL PROTEINS

- M protein - Fimbriae and Outer Membrane Protein - Mycolic Acid - Antigenic variation

→heat resistant and acid resistant protein, mediates attachment to host epithelial cell and helps resist phagocytosis; overcome by antibodies produced this protein

M protein

Neisseria gonorrhoeae - Cell Wall Proteins

Fimbriae and Outer Membrane Protein Antigenic variation

→M. tuberculosis; resist digestion during phagocytosis; the bacteria can even multiply inside macrophages

Mycolic acid

→produced by Streptococci →lyse red blood cells and induce toxic effects on WBC

Hemolysins

→realesed by pathogenic staphylococci →cause lysosomal discharge into cell cytoplasm

Leukocidins

→ Staphylococcal leukocidin →lethal to leukocytes and contributes to the invasiveness of the organism

Panton-Valentine

→cell surface structures that mediate attachment

Adhesins

Main Adhesins in Bacteria:

1. Fimbriae (pili) 2. Surface polysaccharides

→enable bacteria to adhere to host cell surfaces, offering resistance by attachment to target cells, increasing the organism’s colonizing ability

Fimbriae (pili)

→ use lactoferrin as a source of iron

Meningococci

→produce an IgA protease that degrades the IgA found at mucosal surfaces

H. influenzae, N. gonorrhoeae, and N. meningitidis

→circumvent host antibodies by shifting key cell surface antigens

Borrelia spp.

→microorganisms able to multiply intracellularly

Chlamydia, Mycobacterium, Brucella, and Listeria

→ ability to penetrate and grow in tissues

Invasion

→ disease or organisms spread to distant sites Example: Salmonella spp.

Dissemination

highly invasive organism that may not disseminate

Clostridium perfringens

→poisonous substances produced by organisms that interact with host cells, disrupting normal metabolism and causing harm

Toxins

→soluble substances that liquefy the hyaluronic acid of the connective tissue matrix, helping to spread bacteria in tissues, promoting the dissemination of infection

Proteases and Hyaluronidases

→breaks down collagen, which forms the connective tissue of muscles and other body organs and tissues

Collagenase

→hydrolyzes hyaluronic acid, a type of polysaccharide that holds together certain cells of the body, particularly cells of the connective tissue helping the organism spread from its initial site of infection

Hyaluronidase

can cause cellulitis

Streptococcus pyogenes

can cause gas gangrene

Clostridium perfringens

→produced by S. aureus and accelerates the conversion of fibrinogen to a fibrin clot

Coagulase

Kinases

Streptokinase Staphylokinase

→ destroy IgA antibodies found on secretions

Immunoglobulin A protease (IgA protease)

→ destroy neutrophilic leukocytes and macrophages

Leukocidin

→composed of two subunits: nontoxic (binds the toxin to the host cells) and toxic →produced by both gram-negative and gram-positive bacteria

Exotoxins

→secreted by the organism into the extracellular environment, or they are released on lysis of the organism →mediate direct spread of the microorganisms through the matrix of connective tissues and can cause cell and tissue damage

Exotoxins

→encoded by phages, plasmids, or transposons

Toxic Gene

→good antigens and induce the production of antibodies called

ANTITOXINS

When treated with formaldehyde (or acid or heat), the exotoxin polypeptides are converted into _____________, which are used in protective vaccines

TOXOIDS

Examples of EXOTOXINS

✓Diphtheria toxin ✓Tetanospamin ✓Botulism toxin ✓Heat labile enterotoxin by E. coli, Vibrio, Bacillus ✓Verotoxin ✓Erythrogenic toxin ✓Three toxins of B. anthracis (EF, PA, LF) ✓TSST-1

3 principal types on the basis of Exotoxin structure and function:

1. A-B Toxin 2. Membrane-Disrupting Toxins 3. Superantigens

→composed of the LPS portion of the outer membrane on the cell wall of gram-negative bacteria →do not have enzyme activity →secreted in only very small amounts →do not have specificity in their activity on host cells

ENDOTOXINS

→not very potent →not destroyed by heating →less antigenic and induce antibody production in a poor manner →no toxoid have been produced from enough endotoxin

ENDOTOXINS

Effects of Endotoxin

✓Stimulates the fever centers in the hypothalamus (1 hour after exposure) ✓Hypotension (30 minutes after exposure)→Shock ✓Initiates coagulation→DIC ✓Severe neutropenia ✓Activates macrophages, activates complement, and has an adjuvant effect with protein antigens ✓stimulates interferon production and causes changes in carbohydrates, lipids, iron, and sensitivity to epinephrine

→ test to detect endotoxins in drugs, medical devices, and body fluid

Limulus Lysate Test

Limulus Lysate Test Reagent used:

Limulus polyphemus (horse shoe crab)

Principle of the Limulus Lysate test:

in the presence of endotoxin, the horse shoe crab will release amoebocytes which results to positive result of clumping

Positive Result of Limulus Lysate Test:

Clumping (there is endotoxin in the body fluid or bacterial instrument)

C8 - Host Microorganisms Interactions (Part 1) Flashcards

(132 cards)