MICROBIOLOGY
CHAPTER 10- MICROBIAL ECOLOGY & APPLIED BIOTECHNOLOGY
ECOLOGY- the systematic study of the interrelationship that exists between organisms and their environment
MICROBIAL ECOLOGY- is the study of the numerous interrelationships between microbes and the world around them (how microbes interact with other microbes and the non living world around them)
SYMBIOTIC RELATIONSHIPS INVOLVING ORGANISMS
SYMBIOSIS- is defined as the living together or close association of two dissimilar organisms
SYMBIONTS- organisms that live together in such a relationship
NEUTRALISM- used to describe a symbiotic relationship which neither symbiont is affected by the relationship. (no effect on each other)
COMMENSALISM- A symbiotic relationship that is beneficial to one symbiont and of no consequence to the other
MUTUALISM- a symbiotic relationship that is beneficial to both symbionts
(Vitamin k- blood clotting factor)
PARASITISM- A symbiotic relationship that is beneficial to one symbiont & detrimental to the other
DYSBIOSIS- a mutualistic & commensalistic relationship shift
INDIGENOUS MICROBIOTA- includes all the microbes that reside on and within that person
Fetus has no indigenous microbiota
TRANSIENT MICROBES- takes up temporary residence
MICROBIOTA OF THE SKIN- relatively inhospitable environment for microorganisms
• Staphylococcus
• Corynebacterium
• Propionibacterium
MICROBIOTA OF THE EARS & EYES- Middle ear & inner ear are usually sterile
Lysozyme- enzyme present in tears
MICROBIOTA OF THE RESPIRATORY TRACT- nasal passages & throat have an abundant & varied population of microbes
- Lower respiratory tract is usually free of microbes
Streptococcus mutans- bacterium most often implicated in the formation of dental plaque
MICROBIOTA OF THE GI TRACT- gastric enzymes & the acidic pH of stomach usually prevent the growth of indigenous microbiota
- Gram-negative Bacillus (Helicobacter pylori)-cause of ulcer
MICROCOLONIES- tiny clusters of bacteria
SESSILE- transformation of organisms to a quiescent state
SYNERGISM- Two or more microorganisms may "team up" to produce a disease that neither could cause by itself
- Diseases are referred to as synergistic infections
AGRICULTURAL MICROBIOLOGY
- Nitrifying bacteria convert ammonium ions into nitrite ions & nitrate ions
- Ammonification- excreted nitrogen-containing animal waste products are converted by certain bacteria to ammonia
- Denitrifying bacteria- convert nitrates to atmospheric nitrogen gas
OTHER SOIL MICROBES
• Clostridium
• Bacillus
MICROBIAL BIOTECHNOLOGY
• Production of therapeutic proteins
• Production of DNA vaccines
• Production of vitamins
• Use of microbial metabolites as antimicrobial agents & other types of therapeutic agents
• Agricultural applications
• Food technology
• Production of chemicals
• Biomining
• Bioremediation
CHAPTER 11- EPIDIMIOLOGY & PUBLIC HEALTH
EPIDEMIOLOGY-both pathology & epidemiology can be loosely defined as the study of disease but they involve different aspects of disease
Pathologist- studies the structural & functional manifestations of disease & involves in diagnosing the diseases
Epidemiologist- studies the factors that determine the frequency, distribution & determinants of diseases in human populations
COMMUNICABLE & CONTAGIOUS DISEASES- infectious diseases that is caused by a pathogen
COMMUNICABLE- infectious diseases that is transmissible from one human to another
Ex. AIDS, gonorrhoea
CONTAGIOUS- Disease that is defined as a communicable disease that is easily transmitted
Ex. Influenza
ZOONOTIC DISEASES- infectious disease that human acquire from animal sources
INCIDENCE & MORBIDITY RATE
INCIDENCE- Defined as the number of new cases of that disease in a define population during a specific time period
MORBIDITY RATE- number of new cases of a particular disease that occurred during a specified time period
PREVALENCE
PERIOD PREVALENCE- number of cases of the disease existing in a given population during a specific time periodEx. Total number of cases of gonorrhoea during 2017)
POINT PREVALENCE- number of cases of the disease existing in a given population at a particular moment in timeEx. Number of cases of Malaria in the US population at this moment
MORTALITY RATE- the ratio of the number of people who died of a particular disease during a specified time period per a specified population
SPORADIC DISEASE- occurs only rarely & without regularity
ENDEMIC DISEASES- Diseases that is always present within the population of a particular geographic area
EPIDEMIC DISEASE- defined as a greater than usual number of cases of a disease in a particular region, occurring within a relatively short period of time
PANDEMIC DISEASES- disease that occurs in epidemic proportions in many countries simultaneously- worldwide
CHAIN OF INFECTION
1. Pathogen
2. Source of pathogen
3. Portal of exit
4. Mode of transmission
5. Portal of entry
6. Susceptible host
STRATEGIES FOR BREAKING THE CHAIN OF INFECTION
• Eliminate or contain reservoirs of pathogens
• Prevent contact with infectious substances from exit pathways
• Eliminate means of transmission
• Block exposure to entry pathways
• Reduce or eliminate the susceptibility of potential hosts
RESERVOIRS OF INFECTION
Reservoirs- sources of microbes that cause infectious diseases are many & varied
- Site where pathogen can multiply
LIVING RESERVOIRS- Include humans, household pets, farm animals, wild animals, certain insects, etc
HUMAN CARRIERS- A carrier is a person who is colonized with a particular pathogen is not currently causing disease in that person
Passive carriers- carry the pathogen without ever having had the disease (asymptomatic)
Incubatory carrier- a person who is capable of transmitting a pathogen during the incubation period of a particular disease
Convalescent carriers- harbour and can transmit a particular pathogen while recovering from a disease
Active carriers- have completely recovered from the disease but continue to harbour the pathogen indefinitely
MODES OF TRANSMISSION
• Contact (direct/indirect)
• Droplet
• Airborne
• Vehicular
• Vector transmission
PUBLIC HEALTH AGENCIES
• World Health Organization (WHO)
• Centers For Disease Control & Prevention
BIOTERRORISM & BIOLOGIC WARFARE AGENTS
BIOLOGIC WARFARE- the use of microbes in times of war
BIOLOGIC WARFARE AGENTS- microbes that are used in times of war
• Anthrax- Bacillus anthracis
• Botulism- Clostridium botulinum
• Small pox- serious contagious & sometimes fetal disease
• Plague- Yersinia pestis
WATER SUPPLY & SEWAGE DISPOSAL
WATER TREATMENT
- Water is filtered first to remove large pieces of debris
- Debris settle at the bottom of the tank through sedimentation
- Alum is added to coagulate smaller pieces of debris in the process called coagulation
Diatomaceous earth filters remove the remaining bacteria, protozoan cyst, oocytes
- Sodium hypochlorite is added to kill the remaining bacteria
SEWAGE TREATMENTS
• Primary- large debris is filtered out, skimmers remove floating grease & oil & floating debris
- Primary sludge- material that accumulates at the bottom of the tank
• Secondary- includes aeration or trickling filtration ( to encourage the growth of aerobic microbes which oxidize the dissolved organic matter to CO2 and H2O
• Tertiary- involves the addition of chemicals, filtration, chlorination & distillation
CHAPTER 12- HEALTH CARE EPIMIOLOGY & INFECTION PREVENTION & CONTROL
Health care epidemiology- can be defined as the study of occurrence, determinants & distribution of health & disease within health care settings
Health care- associated Infections (HAIs)
a. Infections that are acquired within hospitals or other health care facilities
b. Infections that are acquired outside health care facilities (community acquired infections)
Iatrogenic infection- infection that results from medical or surgical treatment (UTI from catheterization)
PATHOGENS MOST OFTEN INVOLVED IN HAIs
• Clostridium difficile
• Staphylococcus aureus
• Klebsiella pneumonia & Klebsiella oxytoca
• Escherichia coli
MODES OF TRANSMISSION
Contact:
• Direct- pathogens are transferred from one infected person to another person without a contaminated intermediate object or person
• Indirect – happens when pathogens are transferred via a contaminated intermediate object or person
Droplet
• Respiratory droplets carrying pathogens transmit infection when they travel from the respiratory tract of an infectious individual
Airborne
• Occurs with dissemination of either airborne droplet nuclei or small particles containing pathogens
MOST COMMON TYPES OF HAIs
• C. Difficile- associated gastrointestinal disease
• UTI
• Surgical site infection
• Lower respiratory tract infections
• Bloodstream infection(septicaemia)
PATIENTS MOST LIKELY TO DEVELOP HAIs
• Elderly patients
• Women in labor & delivery
• Premature infants & newborns
• Surgical & burn patients
• Patients with diabetes or cancer
• Patients with cystic fibrosis
MAJOR FACTORS CONTRIBUTING TO HAIs
• an ever increasing number of drug resistant pathogens
• failure of health care personnel to follow infection control guidelines
• an increased number of immunocompromised patients
INFECTION PREVENTION & CONTROL
• Pertains to numerous measures that are taken to prevent infections form occurring within health care settings
Medical asepsis- clean technique involves procedures & practices that reduce the number of transmission of pathogens (exclude pathogens)
Categories of disinfectants:
• Chemical sterilants- few disinfectants that will kill bacterial spores with prolonged exposure times
• High level- kill all microbes
• Intermediate- might kill mycobacterium, vegetative bacteria, some fungi & some viruses but do not kill bacterial spores
• Low level- kill most vegetative bacteria within 10 minutes of exposure
Surgical asepsis- sterile technique, includes practices used to render & keep objects & areas sterile (exclude all microbes)
STANDARD PRECAUTIONS
• Standard precautions- combine major features of Universal precautions & body substance isolation precautions
• Transmission-based precautions- enforced only for certain specific types of infection
VACCINATIONS
• Hepatitis B
• Influenza
• Measles
• Varicella
• Tetanus
• Meningococcal vaccine
HAND HYGIENE- most basic technique & controlling infections & preventing the transmission of pathogens is hand washing
PERSONAL PROTECTIVE EQUIPEMENT
• Gloves
• Isolation gowns (first to be donned)
• Masks
• Respiratory protection
PATIENT CARE EQUIPMENT- Organic material must be removed from medical equipment, instruments & devices prior to high-level disinfection & sterilization
ENVIRONMENT CONTROL- Hospital must have & employees must comply with adequate procedures for the routine care, cleaning & disinfection of environmental surfaces
• Linens
• Disposal of sharps
TRANSMISSION BASED PRECAUTIONS
- Used for patients who are known or suspected to be infected or colonized with highly transmissible or epidemiologically important pathogens for which additional safety precautions beyond Standard precautions are required to interrupt transmission within hospitals
Contact & enteric precautions- most frequent mode of transmission of HAIs.
Droplet precautions- form of contact precaution; produced primarily as a result of coughing, sneezing, & talking as well as during hospital procedures such as suctioning & bronchoscopy
Airborne precautions-involves either airborne droplet nuclei or dust particles containing a pathogen
Patient placement- single-patient rooms are used for patients who might contaminate the hospital environment or who do not
Airborne infection isolation rooms- the preferred placement for patients who are infected with pathogens that are spread via airborne, droplet, nuclei
Protective equipments- referred to as protective isolation or positive pressure isolation. It is a well-sealed single –patient room in which vented air entering the room is passed through HEPA filters
Handling food & eating utensils- contaminated food provides an excellent environment for the growth of pathogens. The combination of hot water & dishwashers is sufficient to decontaminate dishware & eating utensils
Handling fomites- patient's gowns, beddings, towels, & eating & drinking utensils and hospital equipments
Medical waste disposal- materials or substances that are harmful to health are referred as biohazards
CHAPTER 13- DIAGNOSING INFECTIOUS DISEASES
CLINICAL SPECIMENS
• Blood
• Urine
• Feces
• Cerebrospinal Fluid
• Bone marrow
• Pus from wound abscess
• Sputum/ respiratory specimens
• Vaginal swabs/ Genital or STD specimens
"all specimens should be collected using aseptic technique & placed in or transferred into leak proof primary containers/receptacles with a secure closure"
Three components of specimen quality
a. Proper specimen selection
b. Proper specimen collection
c. Proper transport of the specimen to the laboratory
When clinical specimens are improperly collected
a. The etiologic agent may not be found or may be destroyed
b. Overgrowth by indigenous microbiota may mask the pathogen
c. Contaminants may interfere with the identification of pathogens
BLOOD
• Study of blood is called hematology.
• Liquid portion of blood is called plasma
• When a blood specimen is allowed to clot, the liquid portion is called serum
• The cells makes up about 45% of the volume of the blood
• RBC- erythrocytes
• WBC- leukocytes
• Platelets/Plasma- Thrombocytes
• Bacteremia-presence of bacteria in the blood
• Septicemia- serious disease characterized by chills, fever, prostration, & presence of bacteria or their toxins in the blood stream (Gram-negative bacilli)
• Endotoxin- can induce fever & septic shock which can be fatal
• Blood culture is obtained in the anticubital fossa
URINE
• "Clean catch" refers to the fact that the area around the external opening of the urethra is cleansed by an antiseptic towelette or washing with soap & rinsing with water before urinating
• "midstream" refers to the fact that the initial portion of the urine stream is directed into a toilet or bedpan & directed into a sterile container
• Urine should never be collected from the catheter bag
• Failure to refrigerate a urine specimen will cause an inflated colony
Parts to a urine culture
a. Colony count
b. Isolation & identification of the pathogen
c. Antimicrobial susceptibility testing
• Calibrated loop is a bacteriologic loop that has been manufactured so that it contains a precise volume of urine
CEREBROSPINAL FLUID
• Meningitis- inflammation of the membranes or meninges that surround the brain & spinal column
• Encephalitis- inflammation or infection of the brain
• Meningoencephalities- is the inflammation or infection of both the brain & the meninges
• Must be collected into a sterile tube by a lumbar puncture (spinal tap)
• Critical values are laboratory reports that are communicated (usually by telephone) to a health care provider & provide information that may be critical to the proper care of the patient
SPUTUM-
• Pus that accumulates deep within the lungs of a patient with pneumonia, tuberculosis, or other lower respiratory infection
Throat swabs
• Are collected to determine whether a patient has strep throat
WOUND ABSCESS SPECIMENS
• Wound and abscess should be an aspirate rather than a swab specimen
• Pasteurella multocida is frequently isolated from dog & cat bite wound infections
GENITAL/ STD SPECIMENS
• Detection of Chlamydia trachomatis & Neisseria gonorrhoeae be accomplished by molecular assays because of the increased sensitivity of the assays over culture
• Thayer Martin or Martin Lewis agar specialized media
FECAL SPECIMENS
• Should be collected at the laboratory & processed immediately to prevent a decrease in temperature
PATHOLOGY DEPARTMENT
• ANATOMICAL PATHOLOGY- where they perform autopsies in the morgue & examine diseased organs, stained tissue sections
- morgue
- Histopathology
- Cytology
- Electron microscopy
- Cytogenetics laboratory
• CLINICAL PATHOLOGY-
- Chemistry
- Hematology
- Blood bank
- Immunology
RESPONSIBILITIES
• Processes the various clinical specimens that are submitted to the CML
• Isolate pathogens from those specimens
• Identify the pathogens to the species level
• Perform antimicrobial susceptibility testing when appropriate to do so
Mycology section- assist clinicians in the diagnosis of fungal infections
• Potassium hydroxide preparation used & performed on hair clippings, nail clippings & skin scrapings
• Lactic acid preserves morphology
Parasitology section- diagnosis of parasitic disease, specifically infections caused by endoparasites
Virology sections- diagnosis of viral disease
• Observation of intracytoplasmic or intranuclear viral inclusion bodies in specimens by cytologic or histologic examination
MYCOBACTERIOLOGY SECTION
• Assists clinicians in the diagnosis of tuberculosis & other mycobacterium infections
MOLECULAR SECTION
• Specializes in molecular diagnostic techniques for identifying pathogens
CHAPTER 14- PATHOGENESIS OF INFECTIOUS DISEASES
Path- Greek word "pathos" meaning disease
Pathogen- a microbe capable of causing disease
Pathology- the study of the structural & functional manifestations of disease
Pathogenity- the ability to cause disease
Pathogenesis- the steps or mechanisms involved in the development of a disease
INFECTION VERSUS INFECTIOUS DISEASE
- Infectious disease- is a disease caused by a microbe and the microbes that cause infectious disease are collectively referred to as pathogens
- Infection- mean colonization by a pathogen
- That pathogen may or may not go on to cause disease
- A person has possibility to be infected with a certain pathogen but not have the infectious disease
WHY INFECTION DOES NOT ALWAYS OCCUR
• The microbe may land at an anatomic site where it is unable to multiply
• Many pathogens must attach to specific receptor sites
• Antibacterial factors that destroys or inhibit the growth of bacteria
• The indigenous microbiota at the site may produce antibacterial factors
• The individuals's nutritional and overall health status often the outcome of the pathogen
• The person may be immune to that particular pathogen or having been vaccinated against that pathogen
• Phagocytic white blood cells present in the blood and other tissues may engulf & destroy the pathogen
FOUR PERIODS OR PHASES IN THE COURSE OF AN INFECTIOUS DISEASE
1. Incubation period- is the time that elapses between arrival of the pathogen and the onset of symptoms
2. Prodromal period- is the time during which the patient feels "out of sorts" but does not yet experience actual symptoms of the disease
3. Period of illness- is the time during which the patient experiences the typical symptoms associated with that particular disease
4. Convalescent period- is the time which the patient recovers
LOCALIZED VRSUS SYSTEMIC INFECTIONS
- An infection may be localized to one site or it may spread
- A systemic infection is an infection that has spread throughout the body
ACUTE, SUBACUTE, CHRONIC DISEASES
Acute- rapid onset usually followed by a relatively rapid recovery
Subacute- disease which come on more suddenly than an acute disease but less suddenly than an acute disease
Chronic- has an insidious (slow) onset and lasts a long time
SYMPTOMS OF A DISEASE VERSUS SIGNS OF A DISEASE
SYMPTOMS OF A DISEASE- is defined some evidence of a disease that is experienced or perceived by the patient something that is objective
SIGNS OF A DISEASE- defined as some type of objective evidence of the disease
LATENT INFECTIONS- An infectious disease may go from being symptomatic to asymptomatic and then sometime later go back to being asymptomatic
"Latens" meaning to lie hidden
PRIMARY VERSUS SECONDARY INFECTION
- One infectious disease may commonly follow another in which case the first disease is referred to as primary infection
- the second disease is referred to as secondary disease
STEPS IN THE PATHOGENESIS OF INFECTIOUS DISEASES
1. Entry of the pathogen into the bosy
2. Attachment of the pathogen to some tissue within the body
3. Multiplication of the pathogen
4. Invasion or spread of the pathogen
5. Evasion of host defences
6. Damage to host tissues the damage may be so extensive as to cause the death of the patient
VIRULENCE
Virulent- is used as a synonym for pathogenic
Virulence- used to express a measure or degree of pathogenicity
Virulence factors- physical attributes or properties of pathogens that enable them to escape various host defense mechanisms and cause disease
Receptors & adhesions- receptor & integrin are used to describe the molecule on the surface of a host cell that a particular pathogen is able to recognize & attach to
HIV is able to attach to cells bearing a surface receptor called CD4
Adhesion & ligand- are used to describe the molecule on the surface of a pathogen that is able to recognize and bind to a particular receptor
BACTERIAL FIMBRIAE- Are thin, hair like, flexible projections composed primarily of an array of proteins called pilin
- Enable bacteria to attach to surfaces including various tissues within the human body
OBLIGATE INTRACELLULAR PATHOGENS- Must live within host cells to survive & multiply they are referred to as obligate intracellular pathogens
FACULTATUVE INTRACELLULAR PATHOGENS- Facultative intracellular pathogens are capable of both an intracellular & extracellular existence
INTRACELLULAR SURVIVAL MECHANISMS- The two most important phagocytes in the human body are macrophages & neutrophils
CAPSULES- Considered to be virulence factors because they serve an antiphagocytic function
- They protect encapsulated bacteria from being phagocytized by phagocytic white blood cells
FLAGELLA-They enable flagellated bacteria to invade aqueous area of the body that non flagellated
EXOENZYMES- the major mechanisms by which pathogens cause disease are certain exoenzymes or toxins that they produce
NECROTIZING ENZYMES- Pathogens produce exoenzymes that destroy tissues
COAGULASE- Coagulase binds to prothrombin, forming a complex called staphylothrombin
- The protease activity of thrombin is activated in this complex, causing the conversion of fibrinogen to fibrin
KINASES- also known as fibrinolysins have the opposite effect of Coagulase
- The host will cause a fibrin clot to form around pathogens in an attempt to wall them off & prevent them from invading deeper into body tissues
- Are enzymes that lyse clots
HYALURODINASE- spreading factor, enables pathogens to spread through connective tissue by breaking down hyaluronic acid
COLLAGENASE- produced by certain pathogens that breaks down collagen
HEMOLYSINS- Enzymes that cause damage to host's red blood cells
LECITHINASE- major cause of gas gangrene, is able to rapidly destroy extensive areas of tissue, especially muscle tissue
TOXINS- the ability of pathogens to damage host tissues & cause disease may depend on the production & release of various types of poisonous substances
ENDOTOXINS- Can cause serious, adverse, physiologic effects such as fever & shock
- Substances that cause fever are pyrogens
- Gram negative sepsis is known as septic shock
EXOTOXINS- Are poisonous proteins that are secreted by a variety of pathogens
- Most potent exotoxins are neutrotoxins which affect the CNS
- Enterotixins, toxins that affect the GI tract
- Bacteria that produces pus
ANTIGENIC VARIATION- Some pathogens are able to periodically change their surface antigens
CAMOUFLAGE & MOLECULAR MIMICRY- Adult schistosome worms are able to conceal their foreign nature by coating themselves with host proteins
DESTRUCTION OF ANTIBODIES- produce enzyme called immunoglobulin that destroys IgA antibodies
CHAPTER 15- NONSPECIFIC HOST DEFENSE MECHANISMS
Immunoglobulin- another term for antibodies
Host defense mechanisms- ways in which the body protects itself from pathogens – can be thought of as an army consisting of three lines of defense
First two lines of defense are nonspecific these are ways in which the body attempts to destroy all types of substances that are foreign that are foreign to it including pathogens
The third line of defense, the immune response is very specific
- Special proteins called antibodies are usually produced in the body in response to the presence of foreign substances
- These foreign substances are called antigens or "antibody-generating" substances
NONSPECIFIC HOST DEFENSE MECHANISMS
- General and serve to protect the body against many harmful substances
- They are innate & inborn
FIRST LINE OF DEFENSE
SKIN & MUCUS MEMBRANES AS PHYSICAL BARRIERS
- Intact & unbroken skin that covers our bodies represents a nonspecific host defense mechanism
- Even the tiniest cut can serve as a portal of entry for pathogens
- The sticky mucus that is produced by goblet cells within the mucus membrane serves to entrap invaders
CELLULAR & CHEMICAL FACTORS
- The dryness of most areas of the skin inhibits colonization by many pathogens
- Acidity & temperature of the skin inhibits the growth of pathogens
- The oily sebum that is produced by sebaceous glands in the skin contains fatty acids, which are toxic to some pathogens
- Lactoferrin is a protein that binds iron a mineral that is required by all pathogens
Factors that protect gastrointestinal tract:
• Digestive enzymes
• Acidity of stomach
• Alkalinity of intestines
Bile produced in the liver into the small intestine lowers the surface tension & causes chemical changes in bacterial cell walls & membranes that make bacteria easier to digest
Peristalsis & urination serve to remove pathogens from the GI tract, urinary tract respectively
The acidity of vaginal fluid usually inhibits colonization of the vagina by pathogens
MICROBIAL ANTAGONISM
When resident microbes of the indigenous microbiota prevent colonization by new arrivals to a particular site
Factors:
• Competition for colonization sites
• Competition of nutrients
• Production of substances that kill other bacteria
- The overgrowth or population explosion of organisms is called a superinfection
SECOND LINE OF DEFENSE
Transferrin- a glycoprotein synthesized in the liver and has high affinity of iron
Fever- substances that stimulate the production of fever are called pyrogens or pyrogenic substances
- Interleukin a cytokine that is produced by certain WBC is an example of endogenous pyrogen
Interferrons- are small antiviral proteins produced by virus-infected cells. They are called interferrons because they interfere with viral replication
- A-interferron is produced by B-lymphocytes
- B-interferron produced by fibroblasts
- Y-interferron is produced by activated T-lymphocytes & natural Killer cells
COMPLEMENT SYSTEM
- Not a single entity but rather a group of approximately 30 different proteins
- These make up what is called the complement system
- Interaction with each other in a stepwise is known a complement cascade
Opsonization- is a process by which phagocytosis is facilitated by the deposition of opsonins
Acute-phase proteins- plasma levels of molecules collectively referred to as acute- phase proteins increase rapidly in response to infection, inflammation, & tissue injury
Cytokines- chemical mediators that are released form may different types of cells in the human body
- they enable cells to communicate with each other
- they act as chemical messengers both within the immune system
Inflammation- the body normally responds to any local injury, irritation, microbial invasion or bacterial toxin
Sequence of inflammation
1. tissue injury
2. vasodilation
3. increased permeability
4. emigration of leukocytes
5. chemotaxis
6. phagocytosis
signs & symptoms
• redness
• heat
• swelling/edema
• pain
inflammatory exudates- accumulation of fluid, cells, & cellular debris at the inflammation site
purulent exudates/pus- if the exudate is thick & greenish yellow consisting many live & dead leukocytes
Pyogenic microbes- pus producing microbes
Phagocytosis- process by which phagocytes surround & engulf foreign materials
- the three major categories of leukocytes found in the blood are monocytes, leukocytes & granulocytes
- the three types of granulocytes are neutrophils, eosinophils & basophils
- neutrophils & macrophages are the two most important groups of phagocytes
granulocytes are named for the prominent cytoplasmic granules they possess
- phagocytic granulocytes include neutrophils & eosinophils
- Abnormally high number of eosiniphils in the peripheral blood stream is known as eosinophilia
- Basophils also involved in the allergic & inflammatory reactions although they are not phagocytes, contain histamine & other chemical mediators
Macrophages- develop from a type of leukocyte called monocytes during the inflammatory response
Wandering macrophages- those that leave the bloodstream & migrate to infected areas
Fixed macrophages- remain within tissues & organs & serve to trap foreign debris
CHEMOTAXIS
- Phagocytosis begins when phagocytes move to the site where they are neeed
- Result of chemical attractants called chemotactic agents
- Chemotactic agents that are produced by various cells of the human body are called chemokines
ATTACHMENT
- Attachment of the phagocyte to the object to be ingested
- Phagocytes can only ingest objects to which they can attach
Ingestion- phagocyte then surrounds the object with pseudopodia, which fuse together & the object is ingested
Digestion- phagosome next fuses with a nearby lysosome to form a digestive vacuole (phagolysosome) within which killing & digestion occur
Disorders & conditions that adversely affect Phagocytic & inflammatory process
Leukopenia- abnormally low number of circulating leukocytes
CHAPTER 16- SPECIFIC HOST DEFENSE MECHANISMS: AN INTRODUCTION TTO IMMUNOLOGY
Immunology- is the scientific study of the immune system & responses
The immune system is considered to be the third line of defense. It is considered a specific host defense mechanism because it springs into action to defend against a specific pathogen
PRIMARY FUNCTIONS OF THE IMMUNE SYSTEM
• Differentiate between the "self" & "non self"
• Destroy that which is non-self
MAJOR ARMS OF THE IMMUNE SYSTEM
• There are two major arms of the immune system: Humoral immunity & cell-mediated immunity
Humoral immunity- always involves the production of antibodies in response to antigens
IMMUNITY – A significant result is to make a person resistant to certain infectious disease
Acquired immunity- immunity that results from the active production or receipt of protective antibodies during one's lifetime
1. Natural- active acquired immunity which occurs naturally
2. Artificial- not occurs naturally; artificially induced
Vaccine- is defined as material that can artificially induce immunity to an infectious disease usually after injection
Types of vaccine
1. Subunit vaccine- one that uses antigenic portions of a pathogen rather than using the whole pathogen
2. Conjugate vaccines- successful conjugate vaccines have been made by conjugating bacterial capsular antigens to molecules that stimulate the immune system to produce antibodies against the less antigenic capsular antigens
3. Toxoid vaccines- an exotoxin that has been inactivated by heat or chemicals
4. DNA vaccines- only experimental in humans
5. Autogenous vaccines- one that has been prepared from bacteria isolated from a localized injection
PASSIVE ACQUIRED IMMUNITY
- Antibodies formed in one person are transferred to another to protect the latter from infection
- A person receives antibodies rather than producing them
Natural passive- a fetus receiving maternal antibodies in colostrums are examples of natural passive acquired immunity
Artificial passive- accomplished by transferring antibodies form an immune person to a susceptible person
CELLS OF THE IMMUNE SYSTEM
• T Lymphocytes (T cells)
• B lymphocytes (B cells)
• NK cells
• Macrophages
T cells:
• Helper T cells- secretion of cytokines (CD4)
• Cytotoxic T cells- destroy virally infected host cells
• Regulatory T cells- serves as a brake on the immune response to an infection
Immune response to antigens in the blood are usually initiated in the spleen
HUMORAL IMMUNITY
- Antibodies are produced by B cells
Monoclomal antibodies- used in immunodiagnostic procedure
Hybridomas- able to produce large amounts of specific antibodies called monoclomal antibodies
NATURAL KILLER CELLS- Subpopulation of lymphocytes called large granular lymphocytes
- Targets cells including foreign cells, host cells infected with virus or bacteria & tumor cells
HYPERSENSITIVITY & HYPERSENSITIVITY REACTIONS
Hypersensitivity- refers to an overly sensitive or overly reactive immune system
Type 1 hypersensitivity reactions- include classic allergy responses such as hay fever symptoms, asthma, hives GI symptoms (Anaphylactic reactions)
The allergic response- most commonly observed one
- People prone to allergies are called atopic
Localized anaphylaxis- usually involves mast cells degranulation
Systemic anaphylaxis- results from the release of chemical mediators from basophils in the blood stream
Type 2 hypersensitivity reactions
• Are cytotoxic reactions meaning the body cells are destroyed during these reactions
(incompatible blood transfusions, Rh incompatibility)
Type 3 hypersensitivity reactions
• The dark side is that immune complexes (also known as immune complex reactions)
• Serum sickness is a cross-reacting antibody immune reaction
Type 4 hypersensitivity reactions
• Cell mediated reactions
• Observed 24 to 48 hours or longer after exposure or contact
CHAPTER 17- OVERVIEW OF HUMAN INFECTIOUS DISEASES
Microbial intoxication- ingestion of a toxin produced outside the body
INFECTIOUS DISEASES OF THE SKIN
• Epidermis- superficial portion of the skin
• Dermis- inner layer of the skin
• Dermatitis- inflammation of the skin
• Sebaceous glands- glands in the dermis that usually open into hair follicles & secrete an oily substance known as sebum
• Folliculitis- Inflammation of the hair follicle, the sac that contains a hair shaft
• Sty (stye)- Inflammation of a sebaceous gland that opens into a follicle of an eyelash
• Furuncle- a localized pyogenic infection of the skin usually resulting from folliculitis also known as boil
• Carbuncle- a deep-seated pyogenic infection of the skin usually arising from a coalescence of furuncles
• Macule- a surface lesion that is neither raised or depressed such a lesions of measles
• Papule- a surface lesion that is firm & raised, such as lesion of chickenpox
• Vesicle- a blister or small fluid-filled sac such as is seen in chickenpox or shingles
• Pustule- a pus-filled surface lesion
Infectious disease of ears
• Otitis media-infection of the middle ear
• Otitis externa- infection of the outer ear canal
INFECTIOUS DISEASES OF THE EYES
• Conjunctiva- the thin tough lining that covers the inner wall of the eyelid & the sclera
• Conjunctivitis- an inflammation or infection of the conjunctiva
• Keratitis- an infection or inflammation of the cornea the doomed covering over the iris & lens
• Keratoconjunctivitis- an infection that involves both the cornea & the conjunctiva
• Retinitis- an inflammation that involves the retina often caused by viral infection
INFECTIOUS DISEASES OF THE RESPIRATORY SYSTEM
• Bronchitis- inflammation of the mucus membrane lining of the bronchial tubes
• Bronchopneumonia- combination of bronchitis & pneumonia
• Epiglottitis- inflammation of the epiglottis (mouth of the windpipe) may cause respiratory obstruction
• Laryngitis- inflammation of the mucus membrane of the larynx
• Pharyngitis- inflammation of the mucus membrane & underlying tissue of the pharynx (sore throat)
• Pneumonia- inflammation of one or both lungs
• Sinusitis- inflammation of the lining of one or more paranasal sinuses
INFECTIOUS DISEASES OF THE ORAL REGION
• Dental carriers- tooth decay or cavities caused by S. Mutans
• Gingivitis- inflammation of the gingival
• Periodontitis- inflammation of the periodontium
• Thrush- an infection of the oral tissues
INFECTIOUS DISEASES OF THE GASTROINTESTINAL TRACT
• Colitis- inflammation of the colon
• Diarrhea- an abnormally frequent discharge of semisolid or fluid fecal matter
• Dysentery- frequent watery stools accompanied by abdominal pain, fever & dehydration (with blood or mucus)
• Enteritis-inflammation of the intestines (small intestine)
• Gastritis- inflammation of the mucosal linings of the stomach & intestines
• Hepatitis- inflammation of the liver usually the result of viral infection but can be caused by toxic agents
INFECTIOUS DISEASES OF THE GENITOURINARY SYSTEM
• Urinary tract infections
Upper UTI-
• Nephritis- infections/ inflammation in the kidneys
• Ureteritis- inflammation of the ureters
Lower UTI-
• cystitis- infection of the urinary bladder
• urethritis- inflammation of the urethra
• Prostatitis- inflammation of the prostate
INFECTIONS OF THE GENITAL TRACT
• Bartholinitis- inflammation of the bartholin ducts in women
• Cervicitis- inflammation of the cervix
• Endometritis- inflammation of the endometrium
• Epididymitis- inflammation of the epididymis
• Pelvic inflammatory disease- inflammation of the fallopian tube
• Vaginitis- inflammation of the vagina
STD- formerly called venereal disease includes any of the infections transmitted by sexual activities
INFECTIOUS DISEASES OF THE CIRCULATORY SYSTEM
• Endocarditis- inflammation of the endocardium
• Myocarditis- inflammation of the myocardium
• Pericarditis- inflammation of the pericardium
Lymphatic system
• Lymphadenitis- inflamed & swollen lymph nodes
• Lymphadenopathy- diseased lymph nodes
• Lymphangitis- inflamed lymphatic vessels
INFECTIOUS DISEASES OF THE CENTRAL NERVOUS SYSTEM
• Encephalitis- inflammation of the brain
• Encephalomyelitis- inflammation of the brain & spinal cord
• Meningitis- inflammation of the membranes (infection of the CNS having multiple causes)
• Meningoencephalitis- inflammation of the brain & meninges
• Myelitis- inflammation of the spinal cord
OPPORTUNISTIC INFECTIONS
• Aspergillosis & other mould infections-
• Candidiasis- a yeast infection in the mouth
• Cytomegalovirus- can cause eye disease that can lead to blindness
• Herpes simplex virus infection- the cause of oral herpes & genital herpes
• Malaria- a parasitic infection that occurs in immunocompetent individuals
• Mycobacterium avium-a bacterial infection that can cause recurring fevers, problems with digestion & serious weight loss
• Pneumocystis pneumonia- a fungal infection that can cause fatal pneumonia
• Toxoplasmosis- a protozoal infection of the eyes & brain
• Tuberculosis- a bacterial lower respiratory infection can cause meningitis
EMERGING & REEMERGING INFECTIOUS DISEASE
• Avian influenza
• Chikungunya virus infection
• Cryptococcus gattii infection
• Cryptosporidiosis infection
• Dengue fever/ dengue hemorrhagic
• E coli O157 infection
• Ebola
• Hantavirus Pulmonary syndrome
• Hendra virus infection
• HIV infection/ AIDS
• Lassa fever
• Legionellosis
• Lyme disease
• Marburg hemorrhagic fever
• Middle East Respiratory Syndrome (MERS)
• NIpah virus encephalitis
• Severe acute respiratory syndrome (SARS)
• Variant Creutzfeldt-jakob disease
• West nile encephalitis
• Zika virus infection
