midterm - micro
TRANSCRIPT
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MIDTERM TOPICS
MICRO-PARA
Controlling Microbial Growth in Vitro
Using Antimicrobial Agents to Control Microbial Growth
Microbial Ecology
Epidemiology and Public Health
Health Care Epidemiology: Nosocomial Infections andInfection Control
Diagnosing Infectious Disease
Pathogenesis of Infectious Diseases
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Controlling Microbial Growthin Vitro
Some places encourage the growth ofmicroorganisms.
Some places necessitates inhibition ofthe growth of microorganisms.
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Factors that Affect Microbial Growth
Nutrients
various chemical compounds to sustain life For energy sources
Sources of C-H-O-N-S + Phosphorus andother elements
Na+, K+,Cl-,Mg++, Ca++
Trace elements Fe, I, Zn
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Moisture
Cells consist of 70 95% water, most willdie in environments with too little water.
Other microbial stages (endospores andprotozoan cysts) can survive desiccation intheir dormancy or resting states
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Temperature
Thermophiles Mesophiles
Psychrophiles
Psychroduric organismsprefer warmer temp,but can tolerate very cold temperature (eg.Psychroduric E. coli from fecal material left byearly Arctic explorers)
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pH
Most microorganisms prefer a neutral orslightly alkaline growth medium (7.0 7.4)
Acidophiles survive acid stomach (2.0-5.0)
Alkalophiles found in the intestines (9.0)V. cholerae only human pathogen that grows
well above pH 8.0
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Osmotic pressure and salinity
Pressure exerted on a cell membraneby solution both inside and outside thecell.
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Types of solutions:
Isotonicequal concentration of solutesoutside and inside the cell
Hypertonic - concentration of solutesoutside the cell is greater than inside the
cell Hypotonic - concentration of solutes outside
the cell is lesser than inside the cell
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WHATS THE WORD?
Osmosis movement of a solventfrom lower concentration of solute to a
higher concentration of solute
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Isotonic solution
- Balance solution- No movement of water
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Hypotonic solution
If sufficient water enters the cell, it will
swell, then eventually lyse or burst. Hemolysis bursting of red blood cells.
Plasmoptysis cell rupture of bacterial
cell.
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Hypertonic solution If sufficient water leaves the cell, it will
shrink. Crenation shrinkage of red blood cell
due to loss of water.
Plasmolysis shrinking away of bacterial
cell membrane and cytoplasm from thecell wall. (Application :Use of salt andsugar in food preservation)
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WHATS THE WORD?
Haloduric organisms do not prefer tolive in salty environments but are
capable of surviving there (such asStaphylococcus aureus)
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Dead Sea Salt Beds, Israel
The Dead Sea, between Jordan and Israel, has grown smaller over the last10,000 years due to evaporation, which removes water faster thanprecipitation can replenish it. The resulting salt deposits form an enormoussalt reserve.
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Barometric Pressure
Barophiles thrive deep in the ocean wherethe atmospheric pressure is very high
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Gaseous Atmosphere
Aerobes
Anaerobes
Capnophiles
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JUST ASKING. . .
WHY IS THE GROWTH OF
MICROORGANISMS ENCOURAGED INMICROBIOLOGY LABORATORIES?
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Identification of pathogens
Learn more about them
Harvest antibiotics and other microbialproducts
Produce vaccines
Used in industries
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CULTURING BACTERIA IN THELABORATORY
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Culture medium
possess nutritional and other environmentalrequirements for bacterial growth
Culture
growth of microorganisms obtained fromculture medium
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CultureTypes
Pure only one specie is present (important for
the isolation of pathogenic organism)
Mixed different species
Stock pure culture of microorganisms used asa source of supply for industry, research andstudents use
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Classification of Culture Media
According to consistency (physical state)
Liquid- no agar, hardening or solidifying agent TSB, thioglycollate broth, tetrathionate broth
Semi- solid- 0.5 1.0 % agar SIM
Solid- 2- 3% agar BAP, Citrate, EMB, MacConkey
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According to Composition
Synthetic (Artificial) - exact composition is known(Any commercially prepared medium)
Non-synthetic- exact composition is not known(Meat extract broth)
Tissue Culture- from living cells- for culture ofviruses and rickettsia
(WI 38 from normal human skin)( Hela cells from human cervical cancer cells)
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How the Medium is dispensed
Tubed
Plated- sterile Petri dishes
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According to Use
Simple- with nutrients to support growth
allows most non-fastidious organisms to growat their natural rate
used for routine culture Nutrient Agar
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Enriched- with nutritive supplements needed forbacterial growth
Blood Agar Plate (+ 5% sheep red blood cells)
Chocolate Agar Plate N. gonorrheae
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Differential - organisms growing together withdifferences in their cultural characteristics
EMB and Mac Conkey
lactose fermenters (red)
non-lactose fermenters(colorless)
Blood Agar Plate alpha (partial/incomplete hemolysis)
beta (complete hemolysis/ clear)
gamma (no hemolysis)
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Selective- with one or more agents inhibitory to allorganisms EXCEPT organisms being sought
SSA - BSA (S. typhi) PEA Gram (+) cocci
CNA Columbia Colistin Nalidixic Acid Gram(+) streptococci
Mannitol Salt Agar for Salt tolerant bacteria
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THIO - Thioglycollate broth
Primary isolation medium that supports thegrowth of obligate aerobes to obligateanaerobes
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WHATS THE WORD?
INOCULATION
Adding a portion of the specimen to themedium
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WHATS THE WORD?
STERILE TECHNIQUE
Techniques used in an attempt to createan environment that is sterile (devoid ofmicroorganisms)
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WHATS THE WORD?
INCUBATION
Holding a culture at a particulartemperature for a certain length of time
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TYPES OF INCUBATOR USED IN ACLINICAL MICROBIOLOGY LABORATORY
Carbon dioxide incubator With 15 20 % Oxygen
With 5 10% Carbon dioxide
Non - Carbon dioxide incubator With 20 21 % Oxygen
Anaerobic incubator With atmosphere devoid of oxygen
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BACTERIAL POPULATION COUNTS
VIABLE PLATE COUNT
Used to determine the number of viablebacteria in a liquid sample, such as milk,water, ground food diluted in water, or abroth culture.
It is also an important part of urineculture as an indicator of Urinary TractInfection
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DEVELOPMENTAL MILESTONESIN INFANCY
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uman growth refers to increase in size;going from a tiny baby to a large adult
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Bacterial Growth Curve
when bacteria are grown in suitable mediaand samples taken at intervals, plotting ofresults will yield a characteristic growthcurve.
It tends to increase cell mass and number
in an exponential
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A L Ph
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A. Lag Phase(Phase of Physiologic Youth or
Rejuvinescence)
period of adjustment necessary for
replenishment of cells
maximum cell synthesis
little or no multiplication occurs
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B. Exponential/Logarithmic
maximum rates of cell division and increase
in cell mass
most metabolically active
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C. Stationary /Equilibrium/ Plateau
occurs as essential nutrition in medium begins todisappear
balance between cell growth , cell division and celldeath
number of organisms alive = number of organismsdying
occurs : a. exhaustion of nutrientsb. accumulation of metabolic productsc. changes in pH
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D. Death/ Decline Phase
bacterial lysis and cell destruction
complete cessation of multiplication
increase death rate in medium
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CULTURING OBLIGATE INTRACELLULARPATHOGENS IN THE LABORATORY
OBLIGATE INTRACELLULAR PATHOGENS
Only survive and multiply within living host cell
Examples: Viruses, Rickettsias and Chlamydias
Must be inoculated into embryonated chickeneggs, laboratory animals or cell cultures
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FUNGI
Brain-Heart Infusion Agar Brain-Heart Infusion Agar + Blood
Sabouraud Dextrose Agar
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PROTOZOA
Not usually done Example of protozoa that can be cultured
in vitro are Amebae
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CLOSURE / CARRY-OVER ACTIVITY
Unlock the following terms:
Sterilization Disinfection
Disinfectants
Antiseptics
Sanitazation Germicidal agents
Bactericidal agents
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Microbistatic agent
Bacteriostatic agents
Lyophilization
Sepsis
Asepsis
Antisepsic technique
Thermal Death Point Thermal Death Time
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Sterilization Complete destruction of all microorganisms,
(includes cells, spores and viruses)
Disinfection Destruction /removal of pathogens from non-
living objects by physical or chemical means.
Disinfectants Chemicals used to disinfect inanimate objects
(bedside equipments and operating rooms
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Antiseptics
Solutions used to disinfect skin and other
living tissues
Sanitization
Reduction of microbial populations tolevels considered safe by publicstandards.
G i id l
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Germicidal agents
General term referring to disinfectants
that kill microbes
Bactericidal
Sporicidal
Fungicidal
Algicidal
Viricidal
Pseudomonicidal Tuberculocidal
Microbistatic agent
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Microbistatic agent
Drug/chemical that inhibit the growth ofmicroorganisms
Bacteriostatic agents
One that specifically inhibits the
metabolism and reproduction of bacteria
Lyophilization
Process that combines dehydration(drying) and freezing
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Thermal Death Point
Lowest temperature that will kill all types
of microorganisms in a standardized pureculture within a specified period
Thermal Death Time Length of time necessary to sterilize apure culture at a specified tempertature
i h i l h d hibi
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Using physical methods to InhibitMicrobial Growth
HEAT
DRY HEAT
160 165 C for 2 hours 170 180 C for 1 hour
Use of Oven
Incineration
Flaming
Using electric heating devices
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MOIST HEAT Heat applied in the presence of moisture
(boiling/steaming)
Autoclave like a metal pressure cooker that uses steam
under pressure to completely destroy allmicrobial life.
121.5 C, 15 psi, 20 minutes
Kills veratative microorganisms, bacterialendospores, viruses
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COLD
Inhibits bacterial growth
Refrigeration (slow freezing) Liquid Nitrogen (rapid freezing)
* Refreezing of thawed food is an unsafepractice.
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DESICCATION
Process of being thoroughly dried
Microorganisms grow rapidly in moist,warm nutrient environment.
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RADIATION Suns rays include infrared (heat) rays
and ultraviolet (UV) rays
Penetrate cells and damage DNA
UV lamps are used as germicidal lamps: Nurseries
Operating rooms Elevators
Entryways
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Caution: when working with UV lampsavoid exposure or eyes or skin to the
rays (can cause serious burns andcellular damage)
Skin cancer can be caused by excessiveexposure to UV
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X-rays, gamma rays, beta rays may belethal or cause mutations to
microorganisms
Damage DNA and proteins within the
cell
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ULTRASONIC WAVES
Used in cleaning and sterilizing
equipment delicate equipments inhospitals, medical clinics and dentalclinics.
Sound waves mechanically dislodge
organic debris on instruments and glasswares.
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FILTRATION
Micropore filters are used in the laboratories tofilter bacteria and viruses out of liquids
Variety of filters include plastic films, unglazedporcelein, asbestos, diatomaceous earth, andcellulose membrane filters.
Biologic Safety cabinets contain High-Efficiency
Particulate Air (HEPA) filters.
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GASEOUS ATMOSPHERE
Aerobes and microphiles are killed by
placing them in atmosphere devoid ofoxygen.
Obligate anaerobes are killed by placingthem into an atmosphere containing
oxygen
Using chemical agents to Inhibit
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Using chemical agents to InhibitMicrobial Growth
Factors affecting the efficiency andeffectiveness of disinfectants:
Prior cleaning of the object or surface to bedisinfected
The organic load present in the material to betreated (feces, blood, vomitus, pus)
Bioburden (type and level of microbialcontamination
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Concentration of disinfectant
Contact time (amount of time disinfectant
must remain in contact with the organism inorder to kill them
Physical nature of the object being
disinfected(smooth,rough,crevices,hinges)
Temperature and pH
Characteristics of an Ideal Chemical
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Antimicrobial Agent
Wide antimicrobial spectrum
Fast acting
Not affected by the presence of organic matter
Non-toxic to human tissues, noncorrosive,nondestructive
Should leave a residual antimicrobial film on thetreated surface
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Soluble in water and easy to apply
Inexpensive and easy to prepare
Stable both as a concentrate and as aworking solution
Odorless
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USING ANTIMICROBIAL AGENTS
TO CONTROL MICROBIALGROWTH IN VIVO
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WHATS THE WORD?
CHEMOTHERAPY
Use of drug to treat any disease orcondition
These drugs are calledCHEMOTHERAPUETIC AGENT
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ANTIBIOTICS
Antimicrobial substance produced by amicroorganism that is effective in killingor inhibiting the growth of othermicroorganisms.
Semisynthetic antibiotics chemicallymodified to kill a wider variety ofpathogens or reduce side effects
Ideal Qualities of an Antimicrobial
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Agent
Kill or inhibit the growth of pathogens
Cause no damage to the host
Cause no allergic reaction in the host
Stable when stored in solid or liquid form
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Remain in specific tissues in the bodylong enough to be effective
Kill the pathogens before they mutateand become resistant to it.
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Unfortunately
Most antimicrobials have:
Some side effects
Produce allergic reaction Permit development of mutant strains
Most Common mechanisms of
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Action of Antimicrobial Agents
Inhibition of cell wall synthesis
Damage to cell membranes
Inhibition of nucleic acid synthesis (DNA or RNA)
Inhibition of protein synthesis
Inhibition of enzyme activity
Antibacterial Agents
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Antibacterial Agents(Table 9-1)
Inhibition of cell wall synthesis
Penicillin interferes with the synthesis and
cross-linking of peptidoglycan in Gram(+) like Staphylococcus andStreptococcus
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JUST ASKING. . .
WHY DOESNT PENICILLIN ALSO
DESTROY HUMAN CELLS?
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COMPETITIVE INHIBITION
Sulfonamide molecule is similar in shape to PABA(para-amino benzaldehyde)
PABA is converted to folic acid which is essentialin the synthesis of some bacterial proteins
If there is no conversion of PABA to folic acid toessential proteins, the bacterial cell will
eventually die Sulfa drugs are BACTERIOSTATIC AGENTS
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JUST ASKING. . .
WILL HUMAN CELLS BE AFFECTED BY
SULFA DRUGS?
O ?
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WHATS THE WORD?
NARROW - SPECTRUM ANTIBIOTICS
Destroys only Gram (+) bacteriaVancomycin
Destroys only Gram (-) bacteria
Colistin and Nalidixic acid
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BROAD - SPECTRUM ANTIBIOTICS
Destructive to both Gram (+) andGram (-) bacteria
Ampicillin
Chloramphenicol
Tetracycline
SOMETHING TO REMEMBER
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SOMETHING TO REMEMBER
Antimicrobial agents work well againstbacterial pathogens because the bacteria(being procaryotic) have different cellular
structures and metabolic pathways that canbe disrupted or destroyed by drugs that donot damage the eucaryotic hosts cell.
MULTIDRUG THERAPY
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MULTIDRUG THERAPY
Two or ore drugs are used simultaneouslyto kill all the pathogens and to preventresistant mutant strains from emerging.
Four drugs used in M. tuberculosae infection
Isoniazid
Rifampin
Pyrazinamide
Ethambutol or Streptomycin
Synergism VS Antagonism
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SYNERGISM
Two antimicrobial agents are used totreat an infectious disease a greaterdegree (effect) than that achieved byeither drug alone.
Trimethoprim + Sulfamethoxazole =
Co-trimoxazole (Bactrim and Septra)
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ANTAGONISM
Two drugs working against each other The extent of pathogen killing is less than
that achieved by either drug alone.
ANTIFUNGAL AGENTS
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ANTIFUNGAL AGENTS
How do they work ?
Binding with cell membrane sterols
(nystatin, amphotericin B)
Interfere with sterol synthesis (clotrimazole and miconazole)
Blocks mitosis or nucleic acid synthesis (griseofulvin and 5-flucytosine)
ANTIPROTOZOAL AGENTS
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ANTIPROTOZOAL AGENTS
How do they work ?
Interfere with DNA and RNA synthesis (chloroquine, pentamidine,quinacrine)
Interfere with protozoal metabolism (metronidazole Flagyl)
ANTIVIRAL AGENTS
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ANTIVIRAL AGENTS
ZIDOVUDINE (AZT)
First antiviral drug effective against HIV
(1987) Coctails (1990s) a combination of
antiviral drugs
SUPERBUGS
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SUPERBUGS
Microorganisms that have become
resistant to one or more antimicrobialagents.
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MRSA (Methicillin-resistant S. aureus)
MRSE (Methicillin-resistant S. epidermidis)
VISA (Vancomycin-Intermediate S. aureus)
VRSA (Vancomycin-Resistant S. aureus)-verycommon in nosocomial infection
VRE (Vancomycin Resistant Enterococcus spp.)
MRTB (Multidrug-Resistant M. tuberculosis)
How can Bacteria Become
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Resistant to Drugs
INTRINSIC RESISTANCE
Lack specific target site for the drug(Mycoplama cellwalless)
Drug cannot cross the bacterial cell wallor cell membrane
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ACQUIRED RESISTANCE
Alteration of drug- binding sites due tochromosomal mutation
Alteration of the structure of the cellmebrane
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Ability of organism to produce enzymesthat destroys the drug (R-factor is passedon to other bacteria via conjugation)
Ability to develop Multidrug- Resistancepumps (MDR transporters)-pumps drug
out of the cell before it causes damage
BETA LACTAMASES
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BETA-LACTAMASES
B-lactam ring the heart of Penicillinand Cephalosporin structures
If B-lactam is destroyed, the antibioticno longer works
Two types of B-lactamases:
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yp
Penicillinases destroys the B- lactamrings of Penicillins
Cephalosporinases destroys the B-lactam ring of Cephalosporins
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Combination of Drugs to Combat theEffect of B-lactamases:
Clavulinic acid + Amoxicillin = Augmentin
Clavulinic acid + Tiracarcillin = Timentin
Sulbactam + Ampicillin = Unasyn Tazobactam + Piperacillin = Zosyn
EMPIRIC THERAPY
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EMPIRIC THERAPY
Clinicians initiate therapy beforelaboratory results are available.
Based on an educated guess basedon prior knowledge/ experiences with
the particular type of infectiousdisease the patient has.
Factors to consider
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Factors to consider. . .
Laboratory result of pathogensidentityrefer to pocket chart.
Is patient allergic to anyantimicrobials?
Age of the patient?
Is patient pregnant? In-patient or out-patient?
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Side Effects
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Side Effects. . .
Allergies
Toxicity (Chloramphenicol aplasticanemia)
Superinfection (opportunists and secondaryinvaders overgrowth)
Antibiotic Associated Diarrhea (AAD) and
Pseudomembranous Colotis (PMC) caused by C.difficile
Candida albicans infection
Closure / Carry Over
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Activity
What Can Clinicians, ParamedicalProfessionals and Patients Do To Help in theWar Against Drug Resistance? (pp154-155)
Editorial Cartoon
Poster
Slogan
Jingle Radio Advertisement
Poem
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Study of the numerous interrelationshipsbetween microorganisms and the worldaround them. Microbes interact with. . .
other microbes
_ organisms other than microbes
non-living world around them
Symbiotic relationships involving
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microorganisms
Symbiosis
Living together or close association oftwo dissimilar organisms (symbionts)
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Neutralism
A symbiotic relationship in which neithersymbiont is affected by the relationship
Different microorganisms occupy thesame etiologic niche, but have absolutelyno effect on each other.
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Commensalism
Beneficial to one symbiont and neitherbeneficial nor harmful to the other.
Many organisms in the indigenous floraare considered commensals.
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Mutualism
Beneficial to both symbionts
E. coli obtains nutrients from foodmaterials ingested by the host andproduces vitamin K which is a bloodclotting factor
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Parasitism
Beneficial to one symbiont anddetrimental to the other organism
SYNERGISTIC RELATIONSHIP
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Microorganisms may team up toproduce a disease that neither couldcause by itself
Synergistic Infection
Example: Oral bacteria can cause
ANUGAcute Necrotizing Ulcerative Gingivitis
INDIGENOUS MICROFLORA
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INDIGENOUS MICROFLORA
MICROFLORA OF THE SKIN
Consists of 30 different types of bacteriaand fungi
Most common species - S. epidermidis
FACTORS AFFECTING THE NUMBER ANDVARIETY OF ORGANISMS IN THE SKIN
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VARIETY OF ORGANISMS IN THE SKIN
Amount of moisture present
pH
Temperature
Salinity
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Presence of chemical waste such asurea and fatty acids
Presence of other microbes whichmaybe producing toxic substances
TABLE 10 - 1
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TABLE 10 1
Anatomic Locations of Bacteria andYeasts Found As Indigenous
Microflora of Humans
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MICROFLORA OF THE EARS AND EYES
Middle ear and inner ear are usuallysterile
Outer ear and auditory canal containsame types of organisms as on the skin
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Coughing, sneezing, blowing of nosecan carry these microbes along theeustacian tube to the middle ear
External surface of the eye islubricated, cleansed and protected by
tears, and the presence of enzymelysozyme and other substances
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MICROFLORA OF THE RESPIRATORY TRACT
Nasal passages and throat have anabundant and varied population of
microorganisms
Healthy carriers harbor virulent
pathogens in their nasal passages orthroats
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MICROFLORA
OF THE ORAL CAVITY (MOUTH)
Shelter for numerous anaerobic andaerobic bacteria
Thrive well in particles of food and in thedebris of dead epithelial cells around theteeth
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Poor dental hygiene results in thedevelopment of dental caries, gingivitisand other periodontal diseases
Species include: Actinomyces,Bacteroides, Lactobacillus, Streptococcus,
Neisseria and Veillonella
MICROFLORA
OF THE GASTROINTESTINAL TRACT
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OF THE GASTROINTESTINAL TRACT
Gastric enzymes and extremely acidic pHof the stomach usually prevent growth ofindigenous microflora and most transient
microbes
Helicobacter pylori lives in some
people s stomachs and is a commoncause of ulcer
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MICROFLORA
OF THE GENITOURINARY TRACT
Healthy kidneys, ureters and urinarybladder are sterile
External opening of the urethra harbormany microbes, including bacteria, yeastsand viruses
Frequent urination prevents UTI
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q p
Most common cause of urethritis:Chlamydia trachomatis, Neisseriagonorrheae and Mycoplasmas through
sexual intercourse
Vaginal secretions are acidic, encouragingthe growth of lactobacilli that produces
lactic acid (inhibit growth of bacteriaassociated with bacterial vaginosis)
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BENEFICIAL ROLE OFINDIGENOUS MICROFLORA
Aids in the synthesis of vitamins K andB12, pantothenic acid, pyridoxine andbiotin
Source of irritants and antigens tostimulate the immune system
MICROBIAL ANTAGONISM
b b
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microbes against microbes
Microflora competes for space andnutrients against newcomers
Effects of antibiotics produced by someorganisms against other microorganisms
Some produce protein bacteriocinswhich kill other bacteria
WHATS THE WORD?
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BIOTHERAPEUTIC AGENTS (PROBIOTICS)
Bacteria and yeasts that are used to
reestablish and stabilize microbial balance
Example: Use of Lactobacillus in yogurt or
in medications
MICROBIAL COMMUNITIES
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BIOFILMS
Complex communities of assortedorganisms
Examples: dental plaque, slippery coatingon rocks, slime that acculmilates
Medical Significance:
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Form on urinary catherter, implants
Implicated in endocarditis, middle ear
infection, kidney stones, etc.
Examples: C. albicans, S. aureus,Enterococcus spp,Klebsiella and
Pseudomonas
WHATS THE WORD?
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BIOTECHNOLOGY
industrial use of microbes in theproduction of certain foods andbeverages, food additives, chemicals,amino acids, enzymes, etc. as well as
refining of ores to obtain copper, uraniumand gold
WHATS THE WORD?
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BIOREMEDIATION
Use of microbes to dispose of industrialand toxic wastes and other environmentalpollutants pesticides, herbicides, oilspills
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EPIDEMIOLOGY
ANDPUBLIC HEALTH
1976
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Legionnaires Disease
severe form of pneumonia, characterizedby headache, chest pain, lung congestion,and high fever. The name is derived froman outbreak at an American Legion
convention in a Philadelphia hotel in July1976.
1992 - 1993
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Escherichia coli O157
A food-borne disease caused by a particular
variant of the common intestinal bacteriumE. coli . Although E. coli is normally present inthe human intestines, the variant E. coliO157:H7 produces toxins that cause bloodydiarrhea and, in some cases, far more severe
problems, including kidney failure and death. Aperson can become infected by eatingcontaminated meat. Thorough cooking kills thebacteria.
1993
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Hantaviruses are carried by specificrodent hosts and are transmitted directlyfrom host to host by virus-laden saliva,urine, and feces.
Humans are infected through exposure tothe dried excretions from infected rodents.Hantaviruses cause two different humandiseases: hemorrhagic fever with renal
syndrome, in which damage to the kidneysis common, and acute respiratory distresssyndrome, in which damage to the lungs iscommon.
1993
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Cryptosporidiosis
A diarrheal disease which resulted fromdrinking water that was contaminatedwith Cryptospridium parvum
2002
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West Nile Virus
infectious organism that can cause fatal
neurological disease in birds, horses, andhumans. The virus is transmitted by the bite ofan infected mosquito. West Nile virus is namedfor a district in Uganda where the virus was firstidentified in humans in 1937.
As the virus spread, U.S. public health officialsworked with local communities to track thespread of the virus and to control mosquitopopulations to prevent virus transmission.
WHATS THE WORD?
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EPIDEMIOLOGY
The study of disease, basically thefactors that determine the following:
Frequency
Distribution
Determinants in human population
These FACTORS are included if it is aninfectious diseases:
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infectious diseases:
Characteristics of various pathogens
Susceptibility of the population resultingfrom overcrowding
Lack of immunization
Nutritional status
Inadequate situation
Location (reservoir)
Various ways it is transmitted
Questions asked by EPIDEMIOLOGISTS:
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What pathogens are causing the infection?
Where do the pathogens come from?
When do certain diseases occur
Why do some diseases occur in some placesbut not in others
How are pathogens transmitted?
Do some diseases occur only at certain timeof the year? If so, why?
TERMINOLOGIES
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COMMUNICABLE DISEASE
Transmission : person to person
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CONTAGIOUS
Communicable disease that is easilytransmitted from one person to another
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ZOONOTIC DISEASES
Infectious diseases that human acquirefrom animal sources
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INCIDENCE
Number of new cases of that disease in adefined population during a specific timeperiod
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PANDEMIC DISEASES
A disease occurring worldwide HIV / AIDS (pp.179 180)
Tuberculosis (p. 180)
Malaria (p. 180)
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BE READY TO UNLOCK MORE
TERMINOLOGIES
Interactions Among Pathogens, Hostsand the Environment
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FACTORS AFFECTING THE OCCURRENCEOF INFECTIOUS DISEASES
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Pertaining to the Pathogen
Virulence Portal of Entry
Number of organisms
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Pertaining to the Host
Health status Nutritional status
Socioeconomic, hygiene,
travel,immune status, substance abuse
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Pertaining to the Environment
Physical factors
Location, climate,
heat,
cold,
humidity, season of the year
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Availability of appropriate reservoir
Sanitary and housing conditions,adequate waste disposals
Availability of potable water
SIX COMPONENTS IN THE INFECTIOUSDISEASE PROCESS
(CHAIN OF INFECTION)
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(CHAIN OF INFECTION)
Presence of a pathogen
Source of the pathogen (reservoir)
Portal of exit Mode of transmission
Portal of entry
Susceptible host
A Case of an Infamous Carrier
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Typhoid Mary
(p.183)
FIVE PRINCIPAL MODES OFTRANSMISSION
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Contact (direct or indirect)
Airborne
DropletVehicular
Vectors
Communicable diseases are transmittedfrom person to person in the following
ways:
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ways:
Direct Skin-to-Skin Contact
Handshake
Direct Mucous membraneMucousmembrane Contact
Kissing
Sexual intercourse
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Indirectly by airborne droplets
Sneezing
Coughing
Indirectly by contamination of foodand water by fecal material
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Indirectly by arthropod vectors Mosquitoes
Flies
Fleas
Indirectly by Fomites
Stethoscope Gloves
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Indirectly by transfusion of blood orblood products
Syringes
Needles
UNLOCK THE FOLLOWINGTERMINOLOGIES
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MORBIDITY RATE
MORTALITY RATE
PREVALENCE SPORADIC DISEASE
ENDEMIC DISEASE
EPIDEMIC DISEASE RESERVOIR OF INFECTION
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PASSIVE CARRIERS
INCUBATORY CARRIERS
CONVALESCENT CARRIERS
ACTIVE CARRIERS
FOMITES
PARENTERAL INJECTION
BIOLOGICAL WARFARE
BIOTERRORISM AGENTS
CARRY-OVER ACTIVITY
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TRACE THE CHAIN OF INFECTION IN AFORM OF A DIAGRAM
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HEALTHCARE EPIDEMIOLOGY:
NOSOCOMIAL INFECTIONS AND
INFECTION CONTROL
HEALTHCARE EPIDEMIOLOGY
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- Any activity designed to study and / orimprove patient care outcomes in any typeof healthcare institution or setting.
- Includes a variety of disciplines andactivities directed at enhancing the qualityof healthcare and preventing and controlling
adverse outcomes.(SHEA)
What is the importance of MICROBIOLOGY tothe healthcare professionals?
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Whether they are working in a hospital,
nursing home, medical or dental clinic,or caring for a sick person they MUSTfollow standardized procedures to
prevent the spread of communicable
diseases.
TWO TYPES OF INFECTIOUS DISEASES(INFECTIONS)
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Hospital acquired (Nosocomial)
Includes those that erupt within 14 daysof hospital discharged
Acquired outside the healthcarefacilities (Community-acquired)
Iatrogenic Infections
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physician induced
Result of medical or surgical treatment(surgeons, physicians,healthcarepersonnel)
Examples: post - surgical woundinfections and urinary tract infections(catheterization)
PATHOGENS MOST OFTEN INVOLVEDNOSOCOMIAL INFECTIONS
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Gram (+) cocci Staphylococcus aureus Coagulase (-) Staphylococcus Enterococcus spp.
Gram (-) bacilli Escherichia coli Pseudomonas aeroginosa
Enterobacter spp. Klebsiells spp.
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Urinary catheters provide asuperhighway for indigenous normalflora to access the urinary bladder
70% of nosocomial infections involveddrug resistant bacteria
HARD TO TREAT NOSOCOMIAL AGENTS
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Pseudomaonas infections
MRTB
VRE
MRSA MRSE
Others (developed drug-resistant) HIV
Candida spp.
Malarial parasites
MOST COMMON TYPES OF NOSOCOMIALINFECTIONS
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1. Urinary Tract Infections
2. Surgical Wound Infections
3. Lower Respiratory Tract Infections4. Bloodstream Infections
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MOST VULNERABLE PATIENTS INHOSPITAL SETTINGS
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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, anti-lymphocyte serum
and radiation Immunosuppressed patients Patients who are paralyzed and undergoing
renal dialysis or catheterization
MAJOR FACTORS CONTRIBUTING TONOSOCOMIAL INFECTIONS
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Increasing number of drug resistantpathogens
Failure of personnel to follow infectioncontrol guidelines
Increased number ofimmunocompromised patients
OTHER FACTORS
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Indiscriminate use of antimicrobial agents
False sense of security about antimicrobial
agents
Lengthy, more complicated type of surgery
Overcrowding of hospitals, shortages ofstaff
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Increase use of less-highly trainedhealthcare workers
Increase use of antiimflammatory andimmunosuppressed agents
Overuse and improper use ofindwelling medical devices
TABLE 12 1 (p.201)
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TWELVE STEPS TO PREVENTANTIMICROBIAL RESISTANCE
AMONG HOSPITALIZED ADULTS
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WHAT CAN BE DONE TO REDUCETHE NUMBER OF NOSOCOMIAL
INFECTIONS?
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WASH HANDS BEFORE YOU . . .
WASH HANDS AFTER YOU. . .
WASH HANDS IN THE FOLLOWINGMANNER. . .
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Roughly 1/3 of adults seem to haveforgotten one of the most basic lessonstheir mothers taught them: wash yourhands properly. Although 95% of people say
that they scrub after using public toilets,researchers from the American Society ofMicrobiology found that only 67 % actuallydo.
PROPER HANDWASHING-It is better tobe safe, than to be sorry.
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SURGICAL ASEPSIS
sterile technique
practices use to keep objects and areassterile
Scrubbing hands and fingernails
Sterile gloves , masks, gowns, shoe cover
Using sterile solutions and dressing
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FIGURE 12-6 (P.207)
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STANDARD PRECAUTIONS
FORINFECTION CONTROL
FIGURE 12-9 (P.210)
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AIRBORNE PRECAUTIONS
FIGURE 12-9 (P.211)
DROPLET PRECAUTIONS
FIGURE 12-12 (P.212)
CONTACT PRECAUTIONS
WORD TO PONDER. . .
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All healthcare workers MUST fullycomprehend the problem of
nosocomial infections, MUST be
completely knowledgeable aboutinfection control practices, and MUST
personally do everything in their
power to prevent nosocomialinfections from occurring.
CARRY OVER - ACTIVITY
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(1/2 CW)
Interview doctors and paramedicalpractitioners of the effective waysemployed in the hospital to reducenosocomial infections.
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DIAGNOSINGINFECTIOUS DISEASES
The proper diagnosis of an infectiousdisease requires the following:
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Taking a complete patient history
Conducting a thorough physical examination ofthe patient
Carefully evaluating the patients signs andsymptoms, and
Implementing the proper selection, collection,transport and processing of appropriate clinicalspecimens
Various clinical specimens used todiagnose or follow up infectious diseases
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Blood Urine Feces Cerebrospinal fluid
Others
It is extremely important that these specimens areof the highest possible quality and that they arecollected in a manner that does not jeopardize
either the patient or the person collecting thespecimen.
When an attending physician suspects thata patient has a particular infectious disease,appropriate clinical specimens must be
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obtained and certain diagnostic tests maybe requested.
The doctor or any qualified healthcareprofessional must select the appropriatespecimen, collect it properly, and thenproperly transport it to the laboratory where
it is processed.
All specimens should be collected ortransferred into a leakproof primarycontainer with a secure closure. Care should
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be taken by the person collecting thespecimen not to contaminate the outside ofthe primary container within the institution, the primary container should be placedinto a second container, which will containthe specimen if the primary containerbreaks or leaks in transit to the laboratory.
Clinical and Laboratory Standards Institute (CLSI)
THREE COMPONENTS OF SPECIMENQUALITY
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Proper selection of the specimen(i.e., to determine the properspecimen)
Proper collection of the specimen
Proper transport of the specimen tothe laboratory
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PROPER SELECTION, COLLECTION ANDTRANSPORT OF CLINICAL SPECIMENS
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Specimen must be properly selected
Specimen must be properly and carefully collected
Specimen should be collected at the right site,where the least contamination is likely to occur
Specimen should be taken before antimicrobial
therapy has begun
The acute stage of the disease is the mostappropriate time to collect most specimens
Exercise care and tact, avoid harming patient or
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causing discomfort or undue embarrassment to thepatient
Collect sufficient quantity of the specimen
Collect specimen in sterile container
Protect specimen from heat and cold and promptdelivery to the lab is a must
Hazardous specimens must be handled with evengreater care to avoid contamination of the courier,patients and healthcare professionals
Use sterile, disposable specimencontainers
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Properly label specimen container,submit with appropriate request slip
Specimen should be delivered to thelab ASAP.
DATA INCLUDED IN THEREQUEST SLIP
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Patients name, age, sex Hospital identification number Name of the requesting physician Info about the type of specimen Site from where it is collected Date and time of collection Initials of the person who colleted the
specimen Information about any antimicrobial agents
taken by the patient
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The proper specimen to diagnose UTIis a clean-catch, mid-stream urine(CCMS). It must be refrigerated until it
can be transported to the laboratory
Cerebrospinal specimen should be
submitted to the laboratory andprocessed immediately
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Routine throat swabs are collected todetermine whether a patient has strepthroat.
N. gonorrheaeis a fastidious pathogen thatis both microaerophilic and capnophilic.Therefore it should be inoculatedimmediately into a highly enriched andhighly selective medium
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Clinicians and people in the paramedicalfield like nurses are aware that something iswrong with a patient when they see some
changes in the person - like his skin color
(eg. yellowish discoloration in jaundice,paleness in anemia or bluish blackdiscoloration in the case of hematoma)
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SIGN
OR
SYMPTOM?
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Symptom of the disease
experienced or perceivedby thepatient (subjective)
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Sign of the disease
objectiveevidenceof the disease(palpation of lumps, enlarged liver orspleen, abnormal heart or breath sound,pulse rate, heart rate, lab results,
ultrasound, CT scan, etc)
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Do all sick people manifest signsand symptoms of the disease?
Symptomatic patient experiencingsymptom
Asymptomatic patient is unaware, notexperiencing any symptoms
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When we study the structural andfunctional manifestations ofdisease we are interested in
PATHOLOGY.
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Prefix Path disease
+logistperson (WHO)
+gencausative agent (WHAT)
+genecityability to cause (WHY)
+ genesissteps in the development(HOW)
Infectionversus
Infectious diseases
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Infection = pathogen ---landed andenters the persons body but may or may
not cause the disease
Infectious disease = pathogen landedand enters the persons body and causethe disease
Why an infection does not always occur?
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Microbes land in anatomic sites where it is unable tomultiply .(eg. H. influeanzae on skin)
Microbes land on sites with no receptors
Antibacterial factors like lysozymes in tears, saliva,perspiration
Indigenous microflora (microbial antgonism)
Indigenous microflora produce antibacterialfactors like bacteriocin
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Individuals health status
Immunity to particular pathogen(vaccination)
Presence of phagocytic wbc
Note : When all the mechanical barriers and
cellular protection fail to do their job
weget sick of infectious diseases
Four periods/phases in thecourse of infectious disease
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The incubation Period- time betweenthe arrival of pathogen and the onset ofsymptoms.
Prodromal Periodfeeling of comingdown with something but are not yet sure
what is it.
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The period of illness time when patientexperiences the typical symptoms : sorethroat, headache, sinus congestion(Communicable dses are most easily
transmitted during the third period)
The convalescent period recoveryperiod (but for certain infectious diseases
permanent damage may be caused bydestruction of tissues. Eg. Deafness myfollow ear infection)
Terminologies:
Localized infectionsdisease localized inone site or it my spread eg. Pimples, boils,
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abscess
Systemic infections(generalized)infection spread throughout the body eg. TB = miliary TB (spread in many internal
organs)
Acute diseases rapid onset followed by
rapid recovery eg. Measles, mumps
Chronic slow onset and lasts a long timeeg. TB
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Virulent strains microbes capableof causing disease eg. encapsulated S.pneumoniae
Avirulent strains not capable ofcausing disease eg. Nonencapsulted S.
pneumoniae
Steps in the pathogenesis of infectiousdisease
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Entry skin (bite of an arthropod),inhalation, ingestion, introduction thru theGUT, introduction directly into the blood)
Attachment to some tissues in the body
Multiplication result in local infection
(abscess) to systemic (throughout thebody)
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Invasion or spread of the pathogen
Evasion of host defenses
Damage to host tissues- extensive
damage = cause of patients death
Virulence factors
(attributes that enable pathogens to attach, escapedestruction and cause disease)
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Attachment
Receptors ( molecules in host cell that apathogen recognize and attach to) and
adhesions (molecules in the pathogen that isable to recognize and bind to a particularreceptor)
Fimbriae (pili) enable bacteria to attach to
surfaces, hair-like
Flagella motility to avoid phagocytosis
Exoenzymes or toxins they produce
(evade host defense mechanism)
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Necrotizing enzymesdestroys tissues (eg. C.perfringens gas gangrene)
Coagulase form sticky coat of fibrin aroundthemselves (eg. S. aureus)
Kinases fibrinolysin ( dissolution of clots)
Hyaluronidase spreading factor destroyshyaluronic acid which cements the tissuestogether
ll d ll
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Collagenases-destroys collagen in tissuesthus enables pathogens to invade tissues(C. perfringens)
Hemolysinscause damage to hosts rbc(hemolysis)
Lecithinase destruction of muscletissues (C. perfringens)
Toxins
Endotoxin released by Gram (-)organisms cauring fevers, chills and
ll h k (l b d d
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eventully shock (low bp and inadequateblood supply to brain and kidneys)
Exotoxins secreted by organisms Neurotoxins target CNS (C. tetani)
Enterotoxins affect GIT (B. cereus)
Exfolitive toxin affects layers of the skin
(S. aureus scalded skin syndrome)
Leukocidins destroy wbc (Stph, Strep,Clostridia)
How can Pathogens escape ImmuneResponse?
A i i i i h bl
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Antigenic variation pathogens able tochange their surface antigens - host cellcannot recognize (eg, influenza virus)
Camouflage and Molecular mimicry somecoat themselves with host protein so as notto be recognized as foreign (eg. N.gonorrheae)
Destruction of Antibodies produceenzymes that destroy IgA antibodies (H.influenza)
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