Midterm - Micro

7/31/2019 Midterm - Micro

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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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Midterm - Micro

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