Transcript Chapter 5 Diversity of Microorganisms Eucaryotic Microbes

Chapter 6
Biochemistry:
The Chemistry of life
• Organic Chemistry: Is the study of
compounds that contain carbon
• Inorganic Chemistry: Involves all other
chemical reactions
• Biochemistry: Is the chemistry of living
cells or it is the study of biology at the
molecular level, or the chemistry of life,
or the study of the biomolecules that are
present within living organisms
Carbon bond (Covalent bond)
•
Single bond--------- e.g
methane
•
Double bond-------- e.g
ethylene
•
Triple bond--------- e.g
acetylene
Hydrocarbon: is an organic
molecule that contains only
carbon and hydrogen atoms
Cyclic Compound: when carbon
atom link to other carbon atom to
close the chain forming ring or
cyclic compound
Carbohydrates:
are biomolecules composed of carbon, hydrogen and oxygen in
the ratio 1:2:1 e.g---- glucose, fructose, sucrose, lactose,
maltose, starch, cellulose, glycogen
• Monosaccharides: are sugars composed of only one ring e.g:
glucose
• Disaccharides( sucrose, lactose, maltose)
– Are double-ringed sugars that result from the combination
of two monosaccharides during this process a removal of
water molecule occur by dehydration synthesis reaction
The bond holding the two monosaccharides together
is glycosidic bond
Hydrolysis reaction:
Disaccharide + water=> two monosaccharides
•
Sucrose + water => glucose + fructose
•
Lactose + water => glucose + galactose
•
Maltose + water =>glucose + glucose
Peptidoglycan: is composed of a repeating disaccharide
attached by polypeptides (effect of antibiotic)
• 3 monosaccharides =>Trisaccharide
• 4monosaccharides=>Tetrasaccharide
• 5monosaccharides=>Pentasaccharid
Polysaccharides: are defined as carbohydrate polymers
containing many monosaccharides
• Polymers: molecules consisting of many similar subunits
• Glycogen: is the common storage molecule in animals and
bacteria and found in the liver and in muscles
• Starch : is the common storage molecule in plants and algae, it
is found in potatoes, vegetables and seeds
Hydrolysis of starch
Starch(polysaccharide)
maltose(disaccharide)
α glucose(monosaccharide)
glucose + Protein => glucoseamine
Lipids:
• Constitute an important class of biomolecules
• Most lipids are insoluble
• But soluble in fat solvents such as ether, chloroform
and benzene
• Fatty acids: are the building blocks of lipids
Lipids-------- fatty acids
• Glycolipids: glucose + lipid
Proteins
• Is the most essential chemicals in all living cells
• Proteins are polymers of amino acid
• Proteins contain C, H, O, N and sometimes S
Protein => amino acids
• 2 amino acids--------- dipeptide
• 3 amino acids--------- tripeptide
• Polymer or chain------ polypeptide
• Enzymes: are protein molecules produced by
living cells and it is known the biological
catalyst (endoenzymes & exoenzymes)
• Catalyst: an agent that speeds up a chemical
reaction without being consumed in the process
Substrate=> Products
Nucleic acids
• Are polymers, composed of nucleotides(building blocks of
nucleic acids), nucleotides in a single strand are held together
by covalent bond
• The two categories of nucleic acids are deoxyribonucleic acid
(DNA the hereditary molecule) and ribonucleic acid (RNA)
• There are three types of RNA, messenger RNA (mRNA),
transfer RNA (tRNA) and ribosomal RNA (rRNA)
• In a double-stranded DNA molecule, the nucleotides in one
strand are connected to nucleotides in the other strand by
hydrogen bond
• DNA is the primary component of chromosomes. Genes are
located along the DNA molecule
• DNA molecules are used as templates to produce other DNA
molecules by the process known as DNA replication
• The most important enzyme in DNA replication
is DNA polymerase
• The flow of genetic information within a cell
follows the sequence DNA---mRNA----protein.
This is known as central dogma
• The information (genetic code) in one gene of a
DNA molecule is used to produce a mRNA
molecule, this process is known as transcription,
the most important enzyme in transcription is
RNA polymerase
• Information in one mRNA molecule is used to
produce a protein, this process is translation
(protein synthesis) and occurs at a ribosome
• Transfer RNA(tRNA) molecules activate amino
acids and transfer them to the growing protein chain.
Specific amino acids are added at the correct
locations because three-nucleotide sequences
(anticodons) on tRNA molecules recognize threenucleotide sequences(codons) on mRNAmolecule.
Chapter 7
Microbial Physiology and
Genetics
Nutritional Requirements:
Categorizing microorganisms according to their energy and
carbon sources:
• Phototrophs…… organisms that use light as an energy
source
• Chemotrophs….. organisms that use chemicals as an energy
source
• Autotrophs……. organisms use carbon dioxide as a carbon
source
• Heterotrophs…… organisms that use organic compounds
other than carbon dioxide as a carbon source
– Photoautotrophs…..algae, plants, some photosynthetic
bacteria (cyanobacteria)
– Photoheterotrophs….some photosynthetic bacteria
– Chemoautotrophs…..some bacteria
– Chemoheterotrophs…protozoa, fungi, animals, most
bacteria
Metabolism:
• All the chemical reactions occurring within a cell
Metabolites:
• Is any molecule that is a nutrient, an intermediate
product or an end product in a metabolic reaction
Types of Metabolism
• Catabolism:
–
The breaking down of larger molecules
into smaller molecules, requiring the breaking
of bonds, and then release energy
• Anabolism:
The assembly of smaller molecules into larger
molecules, requiring the formation of bonds, and
hence energy required for bond formation
• Nucleotide + nucleotide => nucleic acid
• Monosaccharide+ monasaccharide => disaccharide
• Amino acid +amino acid +amino acid => polypeptide
NB: Energy that is released during catabolic reactions is
used to drive anabolic reactions.
•
Energy obtained from sun rays or by catabolic
reaction is stored as ATP molecules (adenosine
triphosphate) which are the major energy-storing in a
cell
ATP=> ADP=>AMP
Aerobic Respiration of Glucose
• The complete catabolism of glucose by the
process known as aerobic respiration occurs in
three phases or chemical pathway:
• Glycolysis=> anaerobic process
• Krebs cycle=>aerobic
• The electron transport chain=> aerobic
Fermentation of glucose:
Fermentation usually take place in anaerobic environment
• Glucose =>fermentationglycolysis=>pyruvic acid +2ATP
• Pyruvic acid=>yeast(saccharomyces)or Zymomonas=>ethyl
alcohol+carbon dioxide
• Pyruvic acid =>bacteria=>lactic acid (cheese, yogurt, pickles,
cured sausages)
• Pyruvic acid=>Lactic acid in muscles (bad)
• Glucose =>oral bacteria streptococcus =>lactic acid (eat the
enamel leads to tooth decay)
• Lactose=>lactic acid bacteria=>curd and whey
• Pyruvicacid=>propionibacterium=>propionic acid (swiss
cheese) flavor + CO2 holes
Biosynthesis of Organic Compounds
• Photosynthesi(light and ATP)
2CO2 + 12H2O => C6H12O6 + 6O2 + 6H2O +ADP + P
• Chemosynthesis:
4H2 + CO2 => CH4 + 2H2O
Bacterial Genetics
• Genetics: The study of heredity: DNA, genes,
the genetic code, chromosomes, DNA
replication, transcription, translation
• Genotype (genome): complete collection of
genes or the genetic makeup of an organism
• Phenotype: physical expression of the
genotype
In human (hair, eye, skin, color)
In bacteria (presence or absence of enzyme,
capsules, flagella, pili)
Phenotype depend on genotype
A mutation
A change in the characteristics of a cell caused by a
change in the DNA molecules (genetic
alteration) that is transmissible to the offspring.
• Beneficial mutation: enables the organism to
survive in an environment where organisms
without mutation would die (resistant to
antibiotic)
• Harmful mutation: leads to the production of a
nonfunctional enzyme which is unable to
catalyze a chemical reaction essential to the life
of the cells, (the cell will die…. Lethal mutation)
• Silent mutation: neutral mutation, which
mean have no effect on the cell
– Spontaneous mutation: mutation which
occur randomly throughout a bacterial
genome with no mutagen(x-rays, U.V. light,
radioactive substance)
– Induced mutation: are produced by agents
called mutagens which increase the rate of
mutation
Ways in which bacteria acquire new genetic
information
Gene transfer: movement of genetic information
between organisms
• Vertical gene transfer: passes genes from parent to
offspring during cell division
• Lateral gene transfer: passes genes to other cells.
In bacteria it occurs by any of the following
mechanisms:
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•
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Transformation: release of DNA fragments
and their uptake by other cells
Transduction: transfer of genes (parts of
DNA) by a prophage from a cell that was
lysogenic to another cell that gets infected
with this phage
Conjugation: transfer of large quantity of
DNA from one living cell to another by direct
contact
Genetic Engineering
An array of techniques to transfer eukaryotic genes,
particularly human genes, into other easily cultured
cells to facilitate the large scale production of
important gene product (e.g Insulin)
Genetic engineering can be achieved by one of the
following techniques:
1. Genetic fusion
2. Protoplast fusion
3. Gene amplification
4. Recombinant DNA: is DNA from two different
species of organisms
Steps:
• Identification of the desired gene on the DNA of
the donor organism
• Culturing of the desired gene
• Transfer of the desired gene to a vector (a virus or
plasmid)
• Insertion of the gene into the DNA of the
recipient organism
Some application
Production of human insulin
Some bacteria are engineered to control insects
that destroy crops (not polluted)
Chapter 8
Controlling Microbial Growth
in Vitro
Factors that affect microbial growth
Microbial growth is affected by many different
environmental factors including:
• Availability of nutrients
• Moisture
• Temperature
• pH
• Osmotic pressure
• Barometric pressure
Terms related to optimum environmental factors:
• Thermophiles: Microorganisms that prefer to live in hot
temperature(minimum:25oC, optimum:50oC-60oC,
maximum:113oC)
• Mesophiles: microorganisms prefer moderate
temperature(minimum:20oC, optimum:20oC-40oC,
maximum:45oC)
• Psychrophiles: microorganisms prefer cold
temperature(minimum:-5oC, optimum10oC-20oC,
maximum:30oC)
NB: Psychrotrophs are a group of psychrophiles that prefer to live
at refrigerator temperature 4oC
• Acidophiles: microorganisms live in acidic
environment(pH<7)
• Alkaliphiles: microorganisms live in alkaline
environment(pH>7) (e.g Vibrio cholera)
NB: neutral environment pH= 7
• Halophiles: microorganisms that live in salty environment
(e.g Vibrio cholera also are Capnophiles)
• Haloduric : microorganisms that do not prefer to live in
salty environments but are capable of surviving there
• Barophiles: microorganisms that live where there is high
baromatic pressure (atmospheric pressure)
Osmotic pressure:
• Is the pressure that is affect on a cell membrane
by solutions both inside and outside the cell.
Osmosis:
• Is defined as the movement of a solvent(water)
through a permeable membrane, from a solution
having a lower concentration of solute to a
solution having a high concentration of solute
Hypertonic solution:
When the concentration of solutes in the environment outside of a
cell is greater than the concentration of solutes inside the cell
• Human red blood cell=> loss of water=> cell shrink
• Shrinkage=> crenation
• Cell=> crenated
• In plant cell=> cell wall not changed but cell membrane shrink
(plasmolysis)
Hypotonic solution:
concentration of solutes outside a cell is less than the
concentration of solutes inside the cell
• Human red blood cells=> burst or lysis ( hemolysis)
• Plant cell=> not burst but pressure increase but with time cell
ruptures (plasmoptysis)
Isotonic solution:
The concentration of solutes inside and outside the cell is equal
Bacterial Population Growth Curve
Lag phase:
is the first phase of the growth curve, during which the bacteria absorb
nutrients, synthesize enzymes, and prepare to cell division. No
increase in number in this phase
Log phase(exponential):
is the second phase of the growth curve. In this phase the bacteria
multiply so rapidly
Stationary phase:
when the nutrients in the liquid medium are used up and the
concentration of toxic waste products of bacteria increase so the rate
of divisions slows, and the number of bacteria that are dividing equals
the number that are dying
Death phase:
As overcrowding occurs, the concentration of toxic waste products
increase and the nutrient supply decreases the microorganisms then
die at a rapid rate
Many industries use the
chemostat
microorganisms are
cultured continuously in
a controlled
environment, which
regulate the supply of
nutrients and the
removal of waste
products
• Yeast=>beer and wine
• Bacteria- Fungi=> antibiotics
Inhibiting the growth of microbiology in vitro
Definition of terms
• Sterilization: is the complete destruction of all living organisms
including spores and viruses
– Dry heat
– Autoclaving (steam under pressure)
– Gas (ethylene oxide)
– Chemicals (formaldehyde)
– Radiation (U.V. and γrays)
• Disinfection: is the destruction or removal of pathogens from
nonliving objects by physical or chemical methods
• Pasteurization: is a method of disinfecting liquids and it is used
today to eliminate pathogens from milk and beverages, and it is
not a sterilization because not all microbes are destroyed
• Disinfectants: chemical agents used to eliminate pathogens
• Antiseptics: are solutions used to disinfect skin and other
living tissue
• Sanitization: is the reduction of microbial populations to
levels considered safe by Public Health Standards (e.g
Restaurants)
• Lyphilization (freeze-drying): using liquid nitrogen, are
microbistatic techniques that are used to preserve microbes for
future use or study
• Sepsis: refer to the presence of pathogens in blood or tissues
• Asepsis: means the absence of pathogens
• Aseptic techniques: are employed to eliminate pathogen (e.g
hand washing- sterile gloves- masks- gowns)
• Antisepsis: is the prevention of infection
• Antiseptic technique: refers to the use of antiseptics.
• Sterile technique: it is used to exclude all microorganisms
from a particular area to be sterile
• Bactericidal agents (bactericides): are disinfectants
that kill bacteria but not endospores (spore coat are
thick and resistant)
Sporicidal – Fungicidal - Algicidal- ViricidalPseudomonicidal – Tuberculocidal
• Bacteriostatic: drug or chemical that inhibits growth
and reproduction of bacteria
Using chemical agents to inhibit microbial growth
Factors affect the efficiency of disinfectants
• Prior cleaning of the object or surface to be disinfected
• Presence of organic materials (feces-blood-vomits-pus) on the
materials being treated
• Bioburden: mean the type and level of microbial contamination
• The concentration of the disinfectant
• The contact time (the amount of time that the disinfectant must
remain in contact with organisms in order to kill them)
• The physical nature of the object being disinfected (smooth or rough
surface)
• Temperature and pH
Characteristics of ideal chemical antimicrobial agent
• It should have a wide or broad spectrum (should kill a
wide variety of microorganisms)
• Fast acting (the contact time should be short)
• Should not be affected by the presence of organic
matter
• Must be nontoxic to human tissues, noncorrosive and
nondestructive to materials
• Should be soluble in water and easy to apply
• Should be inexpensive and easy to prepare
• Should leave residual antimicrobial film on the
treated surface
• Should be stable as concentrate and dilution
• Should be odorless
Chapter 9
Using antimicrobial agents to
control microbial growth in
vivo
The father of chemotherapy is Paul Ehrlich, he use
chemicals to affect bacterial cell not human cell
Antimicrobial agent:
• Antibacterial agents => kills bacteria
• Antifungal agents => kills fungi
• Antiprotozoal agents => kills protozoa
• Antiviral agents => kills virus
The first who discover antibiotics is
Alexander Fleming
Ideal qualities of an antimicrobial agents
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•
•
•
•
Kill or inhibit the growth of pathogens
Cause no damage to the host
Cause no allergic reaction in the host
Be stable when stored in solid or liquid form
Remain in specific tissues in the body long enough to
be effective
• Kill the pathogens before they mutate and become
resistant to it.
NB: Narrow Spectrum & Broad Spectrum Antibiotics.
Synergism: Some infectious diseases are treated by two
drugs because one drug alone will not be effective.
How antimicrobial agents work
• Inhibition of cell wall synthesis
• Damage of cell membranes
• Inhibition of nucleic acid synthesis (either DNA or
RNA synthesis)
• Inhibition of protein synthesis
• Inhibition of enzyme activity
How bacteria become resistant to drugs:
• Intrinsic resistance: bacteria are naturally resistant to
a particular antimicrobial agent because they lack the
specific target (Mycoplasmas no cell wall) or the drug
is unable to cross the organisms cell wall or cell
membrane and thus cannot reach its site of action
• Acquired resistance: bacteria were once susceptible
to a particular drug to become resistant to it by the
following (Table 9-5)
Chapter 10
Environmental Microbiology
Microbial Ecology
Microbial Ecology:
Is the study of the interrelationships
among microorganism and the living and
non-living world around them
Symbiotic Relationships involving Microorganisms
• Symbiosis (Symbiotic relationships): is
defined as the living together or close
association of two different species and the
organism in this relationships is known as
symbionts
• Neutralism: a symbiotic relationship in which neither symbiont is affected
by the relationship
• Commensalism: a symbiotic relationship that is beneficial to one symbiont
and is neither beneficial nor harmful to the other (indigenous microflora of
humans)
• Mutualism: is a symbiotic relationship that is beneficial to both symbionts
– E.coli=> vitamin K (blood clotting factor) to the host (human)
– Termite and protozoa
• Parasitism: a symbiotic relationship that is beneficial to one symbiont (the
parasite) and harmful to the other symbiont
NB: A host can harbor a parasite without the parasite causing harm to the host
• There are 2 kinds of parasites:
Smart parasite=> do not cause disease but take only nutrients
Dumb parasite=> kills their hosts then they must either find a new
host or die
Synergism (synergistic infections): sometimes, two or
more microorganisms may “team up” to produce a
disease that neither could cause by itself
Biofilms: In nature microorganisms are often organized
in combination or close association to each other
know as biofilm.
The biofilms have some characteristics including:
1. Very resistant to antibiotics
2. Break down nutrients
3. Produce many different types of proteins
The Nitrogen Fixing Bacteria
•
•
•
•
•
Rhizobium Bacteria
Occur in root nodules
Leguminous plants
Fix nitrogen N2
Mutual symbiotic relationship
Chapter 11
Epidemiology and Public Health
• Communicable Disease: infectious disease
is transmissible from one human to
another(person to person) e.g Gonorrhea
• Contagious disease: infectious disease is
easily transmitted from one person to
another e.g influenza (movie and theatre)
• Zoonotic diseases: infectious diseases that
humans acquire from animal sources
• Incidence and Morbidity rate: is defined
as the number of new cases of that disease
in a defined population over a specific
period
• Prevalence
• Period prevalence of a particular disease is the
number of cases of the disease existing in a given
population during a specific period
• Point prevalence of a particular disease: is the
number of cases of the disease existing in a given
population at a particular moment in time
• Mortality rate (death rate):
is the ratio of the number of people who died of a
particular disease during a specified period per a
specified population
• Sporadic diseases:
Is one that occurs only within the population of a
particular geographic area
Endemic diseases:
• Are diseases that are always present within the
population of a particular geographic area. The number
of cases of the disease may fluctuate over time, but the
disease never dies out completely, e.g Tuberculosis,
Staphylococcus, Streptococcus, Gonorrhea and Syphilis
Epidemic diseases(or outbreak):
• Is defined as a greater than usual number of cases of a
disease in a particular region
Pandemic disease:
• Is a disease that is occurring in epidemic proportions in
many countries simultaneously sometimes worldwide
• HIV/AIDS- Tuberculosis- Malaria
Reservoirs of Infection
Is any site where the pathogen can multiply or merely
survive until it is transferred to a host
Living Reservoirs
1. Human Carrier
A carrier is a person who is colonized with a particular
pathogen but the carrier not causing disease in that
person
– Passive carriers: carry the pathogen without ever having
had the disease
– Incubatory carrier: is a person who is capable of
transmitting a pathogen during the incubation period of an
infectious disease
– Active carriers: have completely recovered from the
disease but continue to harbor the pathogen (typhoid Mary
the cook)
2. Animal Carriers: diseases that humans
acquire it from animal sources are
zoonotic diseases or zoonoses (rabies,
toxoplasmosis from protozoa)
3. Arthropods Carriers (vector) (Insects--mosquitoes, biting flies, lice, fleas)
(Arachnids---mites and ticks)
A vector first take a blood meal from an
infected person or animal and then
transfers the pathogens to a healthy
individual
Non-Living Reservoirs
• Non- living or inanimate reservoirs of
infection include air, soil, dust, food,
milk, water, and fomites
NB: Fomites are: patients gowns, bedding,
towels, eating and drinking utensils and
hospital equipment…etc
Modes of Transmission
See Figure 11-4 and Table 11-5
World Health Organization (WHO)
See Table 11-6
Bioterrorist and Biological Warfare:
• Biological warfare: pathogenic
microorganisms sometimes are used to
cause harm to others
• Biological warfare agents: microbes used
in this process
• Terrorist use pathogens to create fear,
chaos, illness, and death and use
bioterrorist agents (dead bodies in wells)
Water Supplies and Sewage Disposal
• Water is the most essential resource necessary for
the survival of humanity
• Lakes, rivers, reservoirs and groundwater are the
main sources of community water supplies
There are two kinds of pollution:
– Chemical pollution: industrial installation
dump waste products into local waters without
proper pretreatment or pesticides
– Biological pollution: waste product of humans
(fecal materials and garbage) the main cause of
epidemics
Water Treatment
•
•
•
•
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Filtration: water first filtered to remove large
pieces of debris
Sedimentation or settling: water remain in holding
tanks to complete settles of debris to the bottom
Coagulation: addition of Alum[aluminium
potassium sulphate] to coagulate small pieces of
debris, which settle to the bottom
Filtration through sand filter to remove bacteria,
protozoa cysts
Chlorination: 0.2-1.0 ppm to kill most bacteria,
some use O3 or U.V. light
Water considered Potable or Drinkable (safe to
drink) or Suitable for human consumption when
the water samples contain:
less than 1 coliform per 100ml of water.
water contain < 1coliform /100ml
Sewage Treatment
1. Primary Sewage Treatment
– Screening: large debris filtered out, remove floating grease
and oil and debris is ground
– Sedimentation
– Coagulation: to complete settlement
– Accumulation of primary sludge at the bottom
2. Secondary Sewage Treatment
- The liquid undergo aeration or trickling filtration
NB: aeration is to encourage the growth of aerobic
microorganism which oxidize the dissolved organic matter to
CO2 and H2O
-The activated sludge is transferred to a settling tank
-The remaining liquid is filtered and disinfected by chlorination
the effluent pass to rivers or oceans
3. Tertiary Sewage Treatment
In some desert cities where water is in
shortage the effluent water from sewage
is further treated to be returned directly
to drinking water system which is very
expensive
Chapter 12
Healthcare Epidemiology
Nosocomial Infections and
Infection Control
• Nosocomial Infection (hospital-acquired
infections):infectious diseases that are acquired
within hospitals or other healthcare facilities
• Community-Acquired Infections: infectious
diseases are acquired outside of healthcare
facilities
• Iatrogenic Infections: diseases are results of
medical or surgical treatment caused by surgeons
Pathogens most often involved in Nosocomial
infections
• Gram-positive cocci
– Staphylococcus aureus
– Coagulase-negative staphylococci
– Enterococcus spp.
• Gram-negative bacilli
– E.coli
– Pseudomonas aeruginosa
– Enterobacter spp.
– Klebsiella spp.
Most Common Types of Nosocomial Infections
• Urinary tract infection (UTIs)
• Surgical wound infections
• Lower respiratory tract infections (pneumonia)
• Bloodstream infections (septicemia)
Patients most likely to develop Nosocomial
infections
• Elderly patients
• Women in labor and delivery
• Premature infants and newborns
• Surgical and burn patients
• Diabetic and cancer patients
• Patients receiving treatment with steroids,
anticancer drugs, antilymphocyte serum,
radiation
• Immunosuppressed patients (patients whose
immune
systems are not function properly)
• Patients who are paralyzed or are undergoing
renal dialysis or catheterization (normal defense
mechanisms are not functioning properly)
Major factors contributing to Nosocomial infections
• An increasing number of the drug resistant pathogens
• The failure of healthcare personnel to follow infection control
guidelines
• An increased number of immunocompromised patients
• The bad use of antimicrobial agents
• Over crowding of hospitals and healthcare facilities
• Overuse and improper use of indwelling medical devices
What can be done to reduce the number of Nosocomial
infections
Hand washing is the single most important measure to reduce the
risks of transmitting pathogens from one patient to another or
from one anatomical site to another on the same patient
Wash your hands before you:
• Prepare or eat food
• Treat a cut or wound to someone who is sick
• Insert or remove contact lenses
Wash your hands after:
• Use the rest room
• Handle the uncooked food (raw meat- poultry or fish)
• Change a diaper
• Cough- sneeze or blow your nose
• Touch a pet
• Handle garbage
Wash your hands in the following manner:
•
•
•
•
Use warm or hot, running water
Use soap (preferably an antibacterial soap)
Wash all surfaces of your hands
Rub hands together for at least 10-15 seconds
Medical Asepsis
• Medical asepsis: clean technique to reduce the
numbers and transmission or pathogens
• Medical aseptic techniques: hand washing,
personal grooming, proper cleaning of
techniques, disinfection, proper disposal of
needles, contaminated materials.
• Surgical asepsis: or sterile technique to keep
objects and area sterile (free of
microorganisms)
Joseph Lister a British surgeon: contribution in
the area of antisepsis
Source Isolation: patients with
tuberculosis or other contagious diseases
are placed into protective isolation to
protect other people from becoming
infected
Chapter 13
Diagnosing Infectious Diseases
Proper selection, collection, and transport clinical
specimens:
• The specimen must be of appropriate type for diagnosis
of the suspected infectious disease
• The specimen must be properly and carefully collected
• Material should be collected from a site where the
suspected pathogen is found and the least contamination
occur
• Specimens should be obtained before antimicrobial
therapy has begun, or should the lab know what
antimicrobial obtained
• Acute stage is the appropriate time for specimen
collection
• Specimen should be performed with care and no
harm and instruction for sample collection in the
case of urine and sputum
• Sufficient quantity of the specimen must be
obtained
• Specimen should be placed or collected into a
sterile container
• Specimen should be protected from heat and cold
• Sterile, disposable specimen containers should be
used
• Specimen container must be properly labeled
• Specimen should be collected and delivered to the
lab as early in the day as possible
Types of clinical specimens usually required to
diagnose infectious disease:
1.
2.
3.
4.
5.
6.
7.
8.
Blood
Urine (clean-catch, mid-stream urine CCMS urine)
Cerebrospinal fluid
Sputum
Throat swabs
Wound specimens
GC (gonococci)
Fecal specimens.
• Bacterimia=> presence of bacteria in
blood stream
• Bacteuria=> presence of bacteria in urine
• Septicemia=>bacterial toxins in blood
stream(serious disease) chills, fever
The pathology department (the lab)
• Pathology: is the study of the structural and
functional manifestations of disease
• Pathologist: A physician who has had
extensive, specialized training in pathology
Clinical Microbiology Laboratory
See Figure 13-4
Chapter 14
Pathogenesis of Infectious
Disease
• Localized infections:
Disease may remain localized to one site or
it may spread e.g: boils, abscesses, pimples
• Systemic infections or generalized
infection:
When infection has spread throughout the
body by way of lymph, blood
• Acute disease: has a rapid onset, followed
by a rapid recovery e.g: measles, mumps,
influenza
• Chronic disease: has a slow onset and lasts
a long time e.g: tuberculosis, leprosy,
syphilis
• Symptomatic disease or clinical disease:
a disease in which the patient is
experiencing symptoms
• Asymptomatic disease (subclinical): a
disease that the patient is unaware of
because he or she is not experiencing any
symptoms
• Sign of a disease: type of objective
evidence of a disease abnormal heart or
breath sounds, blood pressure, pulse rate,
enlarged liver (hepatomegaly) or spleen
(splenomegaly)
• Latent infections: disease may go from
symptomatic to asymptomatic and some
time later go back to being symptomatic
• Primary infection: one infection disease
may commonly follow another, the first
disease is primary infection and the second
secondary infection
Steps in the pathogenesis of infectious diseases
1. Entry=> penetration of skin, or mucous
membranes, inhalation, arthropods
2. Attachment of pathogen to some tissue
3. Multiplication of the pathogen (localized or
systemic)
4. Invasion/spread of the pathogen
5. Evasion of host defenses
6. Damage the host tissue
• Virulent strains: are capable of causing
disease
• Avirulent strain: are not capable of
causing disease
Virulence factors (enable pathogens to attack,
escape, destruction and cause disease
Chapter 15
Nonspecific Host Defense
Mechanisms
Host defense mechanism:
Ways in which the body protects itself from pathogens
1. Nonspecific host defense:
• First line: skin, mucus membranes, dryness,
pH, temperature, digestive enzymes, acidity of
stomach (pH 1.5), alkalinity of the intestines,
microbial antagonism(competition for
colonization site, for nutrients, production of
substances to kill other bacteria)
2. Second line:
– Transferin: prevent pathogen of essential nutrient
– Fever: stimulation white blood cells to destroy
invador
– Interferon: antiviral(interfere with viral replication)
– inflammation (redness, heat, swelling and pain, pus
formation)
• localize an infection
• prevent the spread of microbial infection
• neutralize any toxins being produced at the site
• aid in the repair of damage tissue
– Phagocytosis (white blood cells are phage cytes)
surround and engulf foreign material
Chapter 16
Specific Host Defense Mechanisms:
An Introduction to Immunology
•
Immunology: is the scientific study of the
immune system and immune responses
• Immunity: is the condition of being immune or
resistant to a particular infectious disease
Acquired Immunity
1. Active acquired immunity
a. Natural active acquired immunity (response
of actual infection)
b. Artificial active acquired immunity (vaccines)
2. Passive acquired immunity
a.
b.
Natural passive acquired immunity (mother to fetus)
Artificial passive acquired immunity (receiving
antibodies
Vaccine: material that can artificially
induce immunity to an infectious
disease, following injection, or ingestion
of the material
Types of Vaccines
• Variety of materials are used in vaccines
• Most vaccines are made from living or dead or
attenuated pathogens
• Or from certain toxins they produce
See page 408
An ideal vaccine
– Contains enough antigens
– Contains antigens from all the strains of
pathogens (polio 3 strains)
– Has few side effects
– Does not cause disease in the vaccinated person
• Antigens (immunogen): any foreign organic
substance that is large enough to stimulate the
production of antibodies
• Antibodies: are glycoproteins produced by
lymphocytes in response to the presence of antigen
Antibodies found in=>tears, saliva, mucous
membranes, colostrum, lymph, blood plasma
• IgG------remote infection
• IgM------recent infection
• Autoimmune disease: when a person’s immune
system no longer recognizes certain body tissues and
attempt to destroy those tissues as foreign
• Immunocompetent person: a person’s
immune system is functioning properly
• Immunosuppressed person or
immunocompromised or
immunodepressed: a person’s immune
system is not functioning properly
Acquired immuno deficiencies caused by
drugs (cancer chemotherapeutic agents,
transplant patients) irradiation, HIV
infection
Immunodiagnostic Procedures
Serologic procedures
See Figure 16-11