normal flora john san tangelo

7/31/2019 Normal Flora John San Tangelo

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John Santangelo


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The different layers of the skin are important defenses of the skin.

Cross-section of skin


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Flora refers to bacteria


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Infection and Disease

A.Definitions

B. The Normal Flora of Humans

C. Generalized Stages of Infection

D. Virulence Factors and Toxins


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Definitions

Disease and Infectious Disease

Disease Any deviation from a condition of good health

and well-being.

Infectious Disease A disease condition caused by the presence or

growth of infectious microorganisms orparasites.


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Definitions

Pathogenicity and Virulence

Pathogenicity The ability of a microbe to cause disease.This term is often used to describe or comparespecies.

Virulence The degree of pathogenicity in amicroorganism.This term is often used to describe or compare

strains within a species.


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Definitions

Acute infection vs. chronic infection

Acute Infection An infection characterized by sudden onset,rapid progression, and often with severesymptoms.

Chronic Infection An infection characterized by delayed onset andslow progression.


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Definitions

Primary infection vs. secondary infection

Primary Infection

An infection that develops in an otherwisehealthy individual.

Secondary Infection An infection that develops in an individualwho is already infected with a differentpathogen.


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Definitions

Localized infection vs. systemic infection

Localized InfectionAn infection that is restricted to a specificlocation or region within the body of thehost.

Systemic InfectionAn infection that has spread to several

regions or areas in the body of the host.


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Definitions

Clinical infection vs. subclinical infection

Clinical InfectionAn infection with obvious observable ordetectable symptoms.

Subclinical Infection An infection with few or no obvioussymptoms.


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Definitions

Opportunistic infection

An infection caused by microorganisms thatare commonly found in the hostsenvironment.

This term is often used to refer to infectionscaused by organisms in the normal flora.

Waiting for the opportunity to cause infection


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Definitions

The suffix -emia

Meaning presence of an infectious agent

Bacteremia = Presence of infectious bacteria.Viremia = Presence of infectious virus.

Fungemia = Presence of infectious fungus.

Septicemia = Presence of an infectious agent inthe bloodstream. (Blood Poisoning)


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Definitions

The suffix -itis

Meaning inflammation of

Pharyngitis = Inflammation of thepharynx.

Endocarditis = Inflammation of theheart chambers.

Gastroenteritis = Inflammation of the

gastointestinal tract. (GIT)


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Definitions

Epidemiology

The study of the transmission of disease.Communicable Disease

A disease that can be transmitted from oneindividual to another.

Noncommunicable Disease A disease that is not transmitted from one individualto another.

Contagious DiseaseA communicable disease that is easily spread fromone individual to another.

The study of the geographic and social-economic distribution of disease.


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Definitions

Endemic DiseaseA disease condition that is normally found in acertain percentage of a population.

Epidemic DiseaseA disease condition present in a greater than usualpercentage of a specific population.

Pandemic DiseaseAn epidemic affecting a large geographical area;often on a global scale.


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Definitions

Reservoir of InfectionThe source of an infectious agent.

CarrierAn individual who carries an infectious agentwithout manifesting symptoms, yet who cantransmit the agent to another individual.

FomitesAny inanimate object capable of being anintermediate in the indirect transmission of aninfectious agent.


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Definitions

Animal VectorsAn animal (nonhuman) that can transmit an infectious agentto humans.

Two types: mechanical and biological

Biological animal vectors : The infectious agent mustincubate in the animal host as part of the agentsdevelopmental cycle; eg, the transmission of malaria by

infected mosquitoes.

Mechanical animal vectors: The infectious agent isphysically transmitted by the animal vector, but the agentdoes not incubate or grow in the animal; eg, thetransmission of bacteria sticking to the feet of flies.


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Definitions

Direct Mechanisms of Disease

TransmissionDirectly From Person to Person.

Examples :Direct Skin ContactAirborne (Aerosols)


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Definitions

Indirect Mechanisms of Disease

TransmissionExamples: Food & Waterborne Transmission.

Fomites.Animal Vectors.


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The Normal Flora of Humans

Types of Symbiosis

Mutualism

A symbiotic relationship in which bothspecies benefit.

CommensalismA symbiotic relationship in which onespecies benefits, and the other species isneither helped nor harmed.


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Normal flora is present in:

- skin

- upper respiratory tract- oral cavity- intestine, especially large intestine

- vaginal tract- Very little normal flora in eyes & stomach


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Notably absent in most all internal organsAbsent in:

- lower respiratory tract- muscle tissue- blood & tissue fluid- cerebrospinal fluid- peritoneum- pericardium- meninges


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Benefits of the normal flora

Nutrient production/processing.e.g. Vitamin K production by E. coli.

Competition with pathogenic microbes.

Normal development of the immune system.

Normal flora and opportunistic infections.


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Generalized Stages of Infection

1. Entry of Pathogen - Portal of Entry

2. Colonization - Usually at the site of entry

3. Incubation Period- Asymptomatic period

Between the initial contact with the microbeand the appearance of the first symptoms.


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4. Prodromal Symptoms- Initial Symptoms

5. Invasive period- Increasing Severity of Symptoms

FeverInflammation and Swelling

Tissue DamageInfection May Spread to Other Sites

Acme (Fastigium)


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6. Decline of Infection

5. Convalescence


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Virulence Factors and Toxins

State of the Host Immune System.

Number of Pathogenic Cellsencountered by the Host.

Infectious Dose.


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Enzymatic Virulence Factors

Examples: Coagluase ( Staphylococcus aureus )Streptokinase ( Streptococcus pyogenes )Hyaluronidase (Many pathogens)

Collagenase (Many pathogens)Leucocidin (Many pathogens)Hemolysin (Many pathogens)


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Adhesion Factors

Examples:Protein A ( Staphylococcus aureus )Protein M ( Streptococcus pyogenes )


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ExotoxinsA type of bacterial toxin with the following properties:

- May be produced by either gram-positive or gram-negative bacteria.- Is secreted by the bacteria.- The action of the exotoxin does not necessarily require

the presence of the bacteria in the host.- Most exotoxins are peptide or protein.- Most exotoxins are heat sensitive (exception:enterotoxin of Staphylococcus aureus )

Staphylococcus Aureus is also known as Golden Staph


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Virulence Factors and ToxinsExo toxins (cont.)

Classes of exotoxins:Neurotoxic, cytotoxic, or enterotoxic exotoxins

Neurotoxins: Interfere with proper synaptictransmissions in neurons.Cytotoxins: Inhibit specific cellular activities,such as protein synthesis.Enterotoxins: Interfere with water reabsorptionin the large intestine; irritate the lining of thegastrointestinal tract.


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Endo toxinsA type of bacterial toxin having the followingproperties:

Produced only by gram-negative bacteria

Endotoxins are a component of the gram-negative cell wallThe action of endotoxin requires the presence ofthe bacteria in the host.The endotoxin may be released from the cellwall as the cells die and disintegrate


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Endotoxins (cont.)

Endotoxin is composed of Lipid A: Part ofthe lipopolysaccharide layer.

Mode of action: Irritation/inflammation ofepithelium, GI irritation, capillary/bloodvessel inflammation, hemorrhaging.


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Our normal flora acts as a protective barrier

The normal flora influences the anatomy, physiology,

susceptibility to pathogens, and morbidity of the host.The composition of the dermal micro flora varies from site to

site according to the character of the microenvironment.

A different bacterial flora characterizes each of threeregions of skin:

(1)axilla, perineum, and toe webs;

(2) hand, face and trunk;

(3) upper arms and legs.

Skin sites with partial occlusion (axilla, perineum, and toewebs) harbour more micro-organisms than do less occluded

areas (legs, arms, and trunk).

Morbidity thedegree or severityof a disease,


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Susceptibility increases where there is a break in the skin.(scratches, mat burns, skin blemishes)

Poor hygiene also increases the hosts susceptibility.

Continued exposure to foreign skin flora promotes disease.


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Identification of Bacteria

1. The site of origin.

2. The type of agar plate it grows on. The temperature.3. The shape and smell of the colony.

4. Whether it haemolyses a blood plate or not.

5. The type of plate used.6. Chemical tests. (fementers etc)

7. Aerobe or anaerobe.

8. Gram Stain.9. Microscopy.

10. Special stains. (ZN for TB) etc.


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John Santangelo


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This nutrient contains charcoal and therefore is black. Inmost swabs, the cotton tip contains the charcoal and not the

nutrient.

It is used when swabbing for Gonorrhoea.The charcoal absorbs the oleic acid in the cotton wool which

would otherwise kill the gonorrhoea.

Nutrient agar with charcoal

Swab Stick


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Swab for general bacterial infections.

It contains nutrient agar only, which keeps the bacteria aliveand prevents multiplication.

The swab before opening

AfteropeningWire, plastic &

wood shafts

are used.

Swabs for Bacterial (red)


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Swabs for Bacterial (red) (sometimes yellow)

Viral Cultures (green) After replacing the viral swab into the container, squash thebottom end with your fingers to break the glass to release thefluid. (Viral swab only)

Glass containing fluid & nutrient


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Flexible wire swabused for

Nasopharyngeal andUrethral Swabs

Nasopharyngeal swab for Whooping cough.(Pertussis)

Urethral swab for gonorrhoea &Chlamydia.


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Convenient kit format for collection of DNAevidence at crime scenes or from suspects andvictims. Can be used for collection of buccal swab samples and blood stains.

Just peel open the pouch, collect the sample and snapthe applicator shaft into the cuvette-tube provided.

Snaps here

Plastic container & lid


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When swabbing a blister caused by Herpes,the blister must be broken and the base of

the opened blister swabbed applying

pressure in a circular motion. If thistechnique is not used, viral recovery will

not be achieved.

Herpes is a Virus so use a Green Swab.


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Herpes Blisters


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MSU Mid Stream Urine

also calledUMCS Urine Micro Culture and Sensitivity

Why do an MSU?

For a Urinary Tract Infection ( UTI )What is a UTI?

An infection of the Urinary Tract.

i.e. kidney, ureters, bladder & urethraIt usually only involves the bladder but any or all

of the above can be involved.

C f UTI


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Causes of a UTIThe most common cause of UTI is bacteria from the

bowel that live on the skin near the rectum whichcan spread and enter the urinary tract through theurethra. Once the bacteria enter the urethra they

travel upwards causing infection in the bladder andsometimes other parts of the urinary tract.

The most common bacteria to cause a UTI is thenormal bacteria that live in the bowel, i.e. E Coli

Females are more often effected because of a short

urethra.Having a bath rather than a shower makes it more

likely to get a UTI .

The bacteria enter by capillary action.


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Performing a Mid Stream Urine The patient is given a Yellow Top container

The container should be sterile but most pathology companies do not use sterile containers

The patient is also given a sterile waterswab to wipe the area from Front toBack .

A small amount of urine is passed intothe toilet to clear the urethra of any bacteria that would contaminate the

specimen. Then, the second catch iscollected into the yellow top container.

Instruct the patient not to touch theinside of the container or lid.

It is best not to do an MSU during amenstrual cycle.

NOTE:


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NOTE:

The Urine can be collected at home or in the collectingroom.

If collected at home, instruct the patient to store it in acool place and bring it in as soon as possible.

Leaving a urine in a warm place for long periods will

cause the bacteria, if present, to multiply and give afalse indication that a more severe infection is present.

Leaving the urine in a cool place will slow down themultiplication of the bacteria.

It should, ideally be brought into the collection roomwithin an hour of collection.


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DipsticksUsed for detecting:

Protein

Blood

Nitrites (infection)

Ketones

Glucose

pH

White Cells (Leukocytes)

Bilirubin

Haemoglobin

Diabetics


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Chlamydia Infection

The second morning urine is collected forChlamydia.

A urethral swab is also done but the

second morning urine is taking over.Flexible wire swab for the urethra

S


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Sputum The mucus and other matter brought up from the

lungs, bronchi and trachea that one may cough up,spit or swallow.

Sputum is borrowed directly from the Latin to spit.It is also called expectoration.

Make sure it is not saliva.

An early morning specimen is recommended as it yields

the best specimen.Because of lack of activity while sleeping, more

secretions accumulate in the lungs.

The sputum must be taken to the collection centre within


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p2 hours.

A sputum is done to detect infection in the lungs or

bronchial tubes. The following instructions are given to the patient when

TB (Tuberculosis) is requested.

TB is also called Acid Fast Bacilli (AFB)

Three early morning sputum specimens are collected andtaken to the collection centre each day.

The container need not be sterile as bacteria other thanAFB is destroyed with Sodium Hydroxide.

The same instructions are used when sputum cytology isrequested.

Sputum Cytology is looking for abnormal cells, usually

cancer cells.


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FaecesFaeces are collected for the following reasons:

Bacteria

Parasites , known as Ova, Cysts & parasites (OCP)especially when diarrhoea is present.

Blood (usually Occult blood) also known as FaecalOccult Blood (FOB)

Fat (for malnutrition)

Mucus

Fungi & Yeasts


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b l l d ( )


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Cerebrospinal Fluid (CSF)The cerebrospinal fluid surrounds the Brain and

Spinal Cord.The CSF is tested for the following:

Bacteria or viruses and Encapsulated yeasts whenmeningitis is suspected.

Protein when a tumour is suspected.

Glucose when a bacterial infection is suspected.

It is important to do a blood glucose as well. Two tubes are taken labelled 1 and 2

Number 2 is used as it is not contaminated with bloodfrom the first traumatic spinal tap.

Af b l H h (bl di i h


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After a cerebral Haemorrhage, (bleeding into thebrain), red cells will be found in the CSF.

If the Red Cells have haemolysed (broken up), the CSFwill have a pinkish to red tinge according to the degreeof haemolysis.

This is called, Xantchromia.


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Other Specimens Joint fluid for Uric Acid Crystals as occurs in Gout.

Joint fluid for TB.

Pleural fluid

Peritoneal fluid

Skin Scrapings

Nail Clippings

Eye, Ear and Nasal SwabsBuccal scrapings for DNA


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PathologyReport


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Dogs are not

allowed onthe beach

The End


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The End

John Santangelo

normal flora john san tangelo

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