Unit 3: Infections and Diseases

**Symbiosis**

* happens when different organisms live and interact together forming an ***interdependent relationship***
* ***long-term interaction***
* *helpful or harmful*

**Mutualism**

* ***Both*** species ***benefit*** from the interaction
* __eg. gut bacteria__ in human and animals that play a role in digestion (__NORMAL FLORA__)

**Commensalism**

* ***One*** organism ***benefits*** while ***other*** organism is ***neither harmed or benefited***
* __eg. bacteria that consume dead skin cells__
* __Yeasts in the__ __*Candida*__ __genera,__ __*Malassezia*____, and__ __*Trichosporon*__ are the best known of those commensals

**Parasitism**

* ***One*** specie ***benefits*** while the ***other*** ***suffers/is harmed***
* ***Destructive or balanced***
* ***Balanced - they require host to be alive***
* __eg. Vibrio cholerae - cholera infection__
* __eg. Giardia lamblia - giardiasis infection__
* __All parasitic microbes__

**Microbiota**

* Complex ecosystem consisting of bacteria, protozoa, viruses, and fungi that varies in number even in body parts of the same individual

**Humans**

* ***are favorable host*** for microbes because of the constant source of ***nourishment*** and ***moisture***, the relatively ***stable pH***, and ***temperature*** for microbial growth, and the ***extensive surface area*** available

**Microbes**

* _____ outnumber human cells by ten folds

**Normal microbiota**

* AKA normal flora, indigenous microbiota

**Normal microbiota**

* The microorganisms that reside on the layers of the skin, oral mucosa, saliva, conjunctiva, and in the GIT of human being

**Factors that determine the composition of normal flora**

* ***Nature of the local environment*** (pH, temperature, redox potential, oxygen, water, and nutrient levels
* ***Peristalsis, saliva, lysozyme secretion, and secretion of immunoglobulins***

**Breast-fed**

* A ***gram-positive (bifidobacteria and lactobacilli)*** predominates in the GI tract early in life if the infant is ***_____***

**Bottle-fed**

* Bacterial population is reduced and displaced somewhat by a ***gram-negative (Enterobacteriaceae)*** when the baby is ***_____***

**Resident Microbiota**

* ***Life-long members*** of the body’s normal microbial community, but are ***not found everywhere***
* Typically colonizes the surface of the skin, mucous membranes, digestive tract, upper respiratory system, and distal portion of the urogenital system

**Transient Microbiota**

* Are microorganisms that are ***just passing through***
* ***May attempt to colonize*** the same areas of the body like resident microbiota ***but*** *transients are* ***unable to remain in the body for extend periods of time*** due to difficulty competing with established resident microbes

**Skin Flora**

1. *Staphylococcus epidermidis*
2. *Staphylococcus aureus*
3. *Micrococcus* species
4. a-Hemolytic and nonhemolytic streptococci
5. *Corynebacterium* species
6. *Propionibacterium* species
7. *Peptostreptococcus* species
8. *Acinetobacter* species

**Nosocomial infection**

**[Skin Flora]**

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* hospital-acquired infection

**Gingival crevice**

**[Oral and Upper Respiratory Tract Flora]**

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* Streptococcal anaerobes inhabit the _____

Nose

**[Oral and Upper Respiratory Tract Flora]**

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* _____ consists of prominent corynebacteria, staphylococci, and streptococci

**Upper respiratory tract**

**[Oral and Upper Respiratory Tract Flora]**

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* nonhemolytic and a-hemolytic streptococci and *Neisseriae*
* Staphylococci, diphtheroids, haemophili, pneumococci, mycoplasmas, and prevotellae are also encountered

**Stomach**

**[Gastrointestinal Tract Flora]**

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* In the **_____**, organisms are usually transient and their population are kept low by the *acidic environment*

**Helicobacter pylori**

**[Gastrointestinal Tract Flora]**

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* Potential pathogen plays a role in the formation of certain ulcer types

**Duodenal**

**[Gastrointestinal Tract Flora]**

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* In normal hosts, the **_____** flora is ***sparse***

**Ileum**

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* The **_____** contains a ***moderately mixed flora***

**Anaerobes**

**[Gastrointestinal Tract Flora]**

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* The **large bowel** is dense and is composed predominantly of ***_____***

Large bowel

**[Gastrointestinal Tract Flora]**

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* Organisms ***participate in bile acid conversion*** and in ***Vit. K and ammonia production*** in the **_____**

**96-99**

**[Gastrointestinal Tract Flora]**

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* Six major phyla predominating a normal adult **colon**, ***_____% of the resident bacterial flora consists of anaerobes*** – *Bacteroidetes*, *Firmicutes*, *Actinobacteria*, *Verrucomicrobiota*, *Fusobacteria*, and *Proteobacteria*

**Anterior urethra**

**[Urogenital Flora]**

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* In the **_____**, S. epidermidis, enterococci, and diphtheroids
* *E*. *coli*, *Proteus*, and *Neisseria*

**Cocci and bacilli**

**[Urogenital Flora]**

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* When pH becomes neutral (until puberty), a mixed flora of _____ is present

Lactobacilli

**[Urogenital Flora]**

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* At puberty, aerobic and anaerobic ***_____*** reappear in large numbers
* *as long as the environment remains acidic*

**B streptococci**

**[Urogenital Flora]**

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* _____ - 25% in **childbearing years**

**Aerobic lactobacilli**

**[Urogenital Flora]**

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* **After birth**, _____ appear

**Menopause**

**[Urogenital Flora]**

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* **After _____**, lactobacilli diminish
* a-hemolytic streptococci, anaerobic streptococci, *Prevotella* species, clostridia, *Gardnerellavaginalis*, *Ureaplasmaurealyticum*, and *Listeria* or *Mobiluncus*

**Flow of tears**

\[**Conjunctival (Eye) Flora]**

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* Few or no microorganisms because it is normally held in check by the _____ which contain antibacterial lyzozyme

**Haemophilus**

\[**Conjunctival (Eye) Flora]**

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* Most detected genera are _____ and Staphylococcus

**Neisseriae**

\[**Conjunctival (Eye) Flora]**

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* Predominating organisms diphtheroids, S epidermidis, and non-hemolytic streptococci
* *_____* and gram-negative bacilli resembling haemophili (*Moraxella* species) are also frequently present

**Opportunistic microorganisms**

* Those that ***take advantage of a situation that arise***
* Non-pathogenic microorganisms that act as pathogen


* ***Dormant for long periods of time and seize the opportunity to attack***

**Immunodeficiency**

* ***Depletion*** of body’s natural immune response or component of it

HIV, Latent Tuberculosis

Examples of opportunistic microorganisms

Protozoan - Toxoplasma gondii

**[Pathogens that Crosses the Placenta]**

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* Condition in the Adult: Toxoplasmosis
* Effect on Embryo or Fetus: Abortion, epilepsy, encephalitis, microcephaly, mental retardation, blindness, anemia, jaundice, rash, pneumonia, diarrhea, hypothermia, deafness

Bacteria - Treponema pallidum

**[Pathogens that Crosses the Placenta]**

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* Condition in the Adult: Syphilis
* Effect on Embryo or Fetus: Abortion, multiorgan birth defects, syphilis

Bacteria - Listeria monocytogenes

**[Pathogens that Crosses the Placenta]**

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* Condition in the Adult: Listeriosis
* Effect on Embryo or Fetus: Granumatosis infantiseptica (nodular inflammatory lesions and infant blood poisoning), death

DNA viruses - Cytomegalovirus

**[Pathogens that Crosses the Placenta]**

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* Condition in the Adult: Usually asymptomatic
* Effect on Embryo or Fetus: Deafness, microcephaly, mental retardation

DNA viruses - Parvovirus B19

**[Pathogens that Crosses the Placenta]**

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* Condition in the Adult: Erythema infectiosum
* Effect on Embryo or Fetus: Abortion

RNA viruses - Lentivirus (HIV)

**[Pathogens that Crosses the Placenta]**

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* Condition in the Adult: AIDS
* Effect on Embryo or Fetus: Immunosuspension

RNA viruses - Rubivirus rubella

**[Pathogens that Crosses the Placenta]**

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* Condition in the Adult: German measles
* Effect on Embryo or Fetus: Severe birth defects or death

**Humans**

**[Seven Capabilities of Pathogens]**

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**1. Maintain a Reservoir**

* _____
* People who are sick
* People who are apparently healthy

**Incubatory carriers**

**[Seven Capabilities of Pathogens]**

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**1. Maintain a Reservoir**

* Humans
* People who are apparently healthy
* _____ - the moment you acquired the organism up to the point you developed a symptom; pero nakakahawa ka na

**Chronic carriers**

**[Seven Capabilities of Pathogens]**

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**1. Maintain a Reservoir**

* Humans
* People who are apparently healthy
* _____ - it has been in the body for a long period of time (eg. typhoid, latent tb)

**Animals**

**[Seven Capabilities of Pathogens]**

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**1. Maintain a Reservoir**

* _____ - zoonoses/zoonotic diseases
* *🗣Diseases transmitted from animal to human (eg. rabies, leptospirosis, yellow fever, malaria, dengue, west nile virus, salmonella)*

**Environment**

**[Seven Capabilities of Pathogens]**

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**1. Maintain a Reservoir**

* _____ - soil, water, food

**Portals of entry**

**[Seven Capabilities of Pathogens]**

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**2. Leave its Reservoir and Enter a Host**

* The most common _____ are the same anatomical surfaces colonized by microbiota
* *🗣Lahat ng openings sa human body (also: pores, thru injection, pag may sugat)*

**Modes of transmission**

**[Seven Capabilities of Pathogens]**

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**2. Leave its Reservoir and Enter a Host**

* _____ - (direct & indirect)
* *🗣Direct: touching, kissing, sexual intercourse*
* *🗣Indirect: airborne, droplets, fomites (inanimate objects na possible may bacteria/etc)*

**Tropism**

**[Seven Capabilities of Pathogens]**

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**3. Adhere to the Surface of the Host (Attachment)**

* Attachment to tissue
* _____ - many bacterial and viral diseases are ***tissue specific***
* *🗣may specific receptors*

**Receptor-mediated Endocytosis (RME)**

**[Seven Capabilities of Pathogens]**

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**3. Adhere to the Surface of the Host (Attachment)**

* Attachment to tissue
* _____ - endocytosis makes use of receptors to engulf molecules. also referred to as clathrin-dependent endocytosis, since clathrin is crucial for the proper execution of this cellular process
* In this technique, specific molecules that get bound to the receptors can only be engulfed by the cell

**Pilli**

**[Seven Capabilities of Pathogens]**

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**3. Adhere to the Surface of the Host (Attachment)**

* Attachment to tissue
* _____ - ***surface proteins*** that ***attach microbe to host*** tissues and cells
* *Ex. bacteriophage - bacteria naiinfect ng viruses*

**Intracellular pathogens**

**[Seven Capabilities of Pathogens]**

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**4. Invade the Body of the Host**

* ***Invasive pathogens*** that __*enter*__ host cells to live are called *_____*
* The cell provides a nutrient-rich environment safe from body defenses

**Capsules**

**[Seven Capabilities of Pathogens]**

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**5. Evade the Body’s Defenses**

* Some pathogens have ***_____*** that ***keep a phagocyte from establishing direct contact***
* Most virulent pathogens are those with thickest _____

Surface proteins

**[Seven Capabilities of Pathogens]**

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**5. Evade the Body’s Defenses**

* *_____* on pathogens also keep phagocytes from establishing contact

***Streptococcus*** ***pyogenes***

**[Seven Capabilities of Pathogens]**

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**5. Evade the Body’s Defenses**

* _____: produces M protein
* M protein is a molecule that gives the streptococcus the ability to resist phagocytosis by polymorphonuclear leukocytes in the absence of type-specific antibodies
* *Yung mga may capsule lang na _____ ang nakakapag-cause ng strep throat*

***Mycobacterium*** ***tuberculosis***

**[Seven Capabilities of Pathogens]**

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**5. Evade the Body’s Defenses**

* *_____* survive inside the phagocyte

**Siderophores**

**[Seven Capabilities of Pathogens]**

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**5. Evade the Body’s Defenses**

* Some pathogens obtain iron by producing iron-binding compounds called _____

**Exotoxin**

**[Seven Capabilities of Pathogens]**

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**6. Multiply Within the Body**

* Highly destructive soluble proteins produced by both gram-positive and gram-negative bacteria
* Most exotoxins are composed of two units, the A (active) unit and the B (binding) unit, and are highly specific

**Endotoxin**

**[Seven Capabilities of Pathogens]**

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**6. Multiply Within the Body**

* Lipopolysaccharide (LPS) component of the outer membrane of gram-negative bacteria. It enters host tissue during division or after cell death
* It acts by stimulating human cells to secrete particular messenger proteins

**Extracellular enzymes**

**[Seven Capabilities of Pathogens]**

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**6. Multiply Within the Body**

* Three types
* **Cytolysins**
* **Hemolysins**
* **Leukocidins**

**Cytolysins**

**[Seven Capabilities of Pathogens]**

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**6. Multiply Within the Body**

* Extracellular enzymes
* _____ - ***attack*** cell membrane

**Hemolysins**

**[Seven Capabilities of Pathogens]**

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**6. Multiply Within the Body**

* Extracellular enzymes
* _____ - ***lyse*** red blood cells

**Leukocidins**

**[Seven Capabilities of Pathogens]**

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**6. Multiply Within the Body**

* Extracellular enzymes
* _____ - ***lyse*** leukocytes

**Portal of entry**

**[Seven Capabilities of Pathogens]**

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**7. Leave the Body and Return to its Reservoir or Enter a New Host**

* The ***portal of exit*** for most respiratory pathogens is the ***same as the _____***

**Anus**

**[Seven Capabilities of Pathogens]**

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**7. Leave the Body and Return to its Reservoir or Enter a New Host**

* Most **gastrointestinal pathogens**’ portal of exit is the _____

**Genital mucous membranes**

**[Seven Capabilities of Pathogens]**

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**7. Leave the Body and Return to its Reservoir or Enter a New Host**

* Most **STDs** exits the same way they entered, through the _____

**Blood**

**[Seven Capabilities of Pathogens]**

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**7. Leave the Body and Return to its Reservoir or Enter a New Host**

* Pathogens transmitted **parenterally** by arthropod vectors exit the ***same way, in a small amount of _____***

**Immunity**

* Ability to ward off damage or disease through our defenses

**Innate Immunity**

* Defenses that are ***present at birth***. This type of immunity is ***fast, non-specific, and has no memory***
* __*Includes: barriers, pH extremes, Phagocytes & NK cells, fever, inflammation, complement, interferon*__

**Adaptive Immunity**

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* ***Slower, specific, and has a memory***. It ***adapts or adjusts*** to handle a specific microbe
* 2 important characteristics: ***specificity*** & ***memory***


1. *🗣specificity: adaptive immunity’s ability to target a specific pathogen*
2. *🗣memory: ability to quickly respond to the infection/pathogen na previously na-encounter na*
* __*Includes: lymphocytes (T-cells & B-cells)*__

**Cytotoxic T cells**

**[Types of Adaptive Immunity]**

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**1. Cell-mediated**

* **_____** directly attack invading antigens 
* *🗣Cell attacking cell; effective against intracellular*
* **Killer cells**

**antibodies (Abs)**

**[Types of Adaptive Immunity]**

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**2. Antibody-mediated/Humoral Immunity**

* *Present sa bodily fluids*
* B cells become plasma cells
* Produce specific proteins called ***_____*** or ***immunoglobulins (Igs)***

**Helper T cells**

**[Types of Adaptive Immunity]**

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**2. Antibody-mediated/Humoral Immunity**

* _____ aid both in cell- and antibody-mediated responses

**B cell**

**[Types of Adaptive Immunity]**

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**2. Antibody-mediated/Humoral Immunity**

* *🗣Para magkaroon ng effective humoral immunity:*


1. *_____activation*
2. *_____ proliferation*
3. *Antigen-antibody interaction*

**IgG**

**[Classes of Immunoglobulins]**

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* Most common
* Most abundant (80%)
* AKA Classic antibody

**IgA**

**[Classes of Immunoglobulins]**

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* Present in mucous membrane, saliva, breastmilk
* AKA Immunosurface protein antibody

**IgM**

**[Classes of Immunoglobulins]**

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* Largest
* AKA **M**acro globulin
* Anti-A and Anti-B antibody in the blood
* First responder; First to fight infection but mabilis mawala so ico-continue ng IgG
* First antibody produced during the primary immune response

**IgD**

**[Classes of Immunoglobulins]**

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* B-cell antigen receptor
* Responsible for B cell maturation

**IgE**

**[Classes of Immunoglobulins]**

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* AKA Regain and homocytotropic antibody
* Allergy, hypersensitivity reaction, asthma, parasitic infection