Transient flora on hands as a vehicle of transmission to food for Staphylococcus aureus Elissa Redmiles and Lucy Erickson.

Transient flora on hands as a Transient flora on hands as a vehicle of transmission to vehicle of transmission to

food for food for Staphylococcus aureus Staphylococcus aureus

Elissa Redmiles and Lucy Erickson Elissa Redmiles and Lucy Erickson

BackgroundBackground

History of food bourn illness

Hypothesis

History of food borne illnessHistory of food borne illness Since the beginning of human history, food borne illness has been an

issue Various food preservation methods have been employed over the

years to slow down food spoilage by microbes and natural aging processes, some common prevention methods include: drying freezing freeze-drying salting curing canning pickling irradiation treating with sugar treating with inert gases (such as carbon dioxide)

S

Transient flora found on human skin and hands Transient flora found on human skin and hands plays an important role in food contaminationplays an important role in food contamination When those involved in food preparation fail to When those involved in food preparation fail to

observe hygienic methodsobserve hygienic methods

History of food borne illness History of food borne illness (cont.)(cont.)

It is hypothesized that It is hypothesized that Staphylococcus aureus, Staphylococcus aureus, a a microbe occurring naturally on the hands of some microbe occurring naturally on the hands of some people, would be found at various locations people, would be found at various locations throughout the Microbiology buildingthroughout the Microbiology building

It was also hypothesized that many different It was also hypothesized that many different types of bacteria would be isolated from the types of bacteria would be isolated from the various locations testedvarious locations tested

HypothesisHypothesis

Hypothesis (cont.)Hypothesis (cont.)

The isolation of bacteria The isolation of bacteria from the inside handle of from the inside handle of the bathroom door the bathroom door particularly holds particularly holds implications for food implications for food hygiene, as ideally it hygiene, as ideally it should only be touched should only be touched by pristinely washed by pristinely washed hands.hands.

Protocol Design and Detailed Protocol Design and Detailed MethodsMethods

Overall approach and rationale for Overall approach and rationale for approachapproach

Detailed methods and rationale Detailed methods and rationale behind methodsbehind methods

Expected resultsExpected results

Overall approach and rationale for Overall approach and rationale for approach approach

There were 2 objectives for this experiment:There were 2 objectives for this experiment:

To determine the number of different types of To determine the number of different types of bacteria that live on each of 7 objects testedbacteria that live on each of 7 objects tested

To identify on which objects To identify on which objects

Staphylococcus aureus Staphylococcus aureus is is

presentpresent

Overall approach and rationale for Overall approach and rationale for approach (cont.)approach (cont.)

To achieve these objectives a growth medium was requiredTo achieve these objectives a growth medium was required Both agar and broth were consideredBoth agar and broth were considered

Agar was determined to be a more suitable growth medium Agar was determined to be a more suitable growth medium since:since:

It allows direct observation of different types of bacterial It allows direct observation of different types of bacterial colonies colonies

It prohibits the number of bacteria on an object from being It prohibits the number of bacteria on an object from being determined determined

Broth was determined to be a less suitable growth medium Broth was determined to be a less suitable growth medium because:because:

It allows the number of bacteria on an object to be It allows the number of bacteria on an object to be determineddetermined

It does not allow direct observation of different types of It does not allow direct observation of different types of bacterial coloniesbacterial colonies

To achieve the first objective a sampling technique To achieve the first objective a sampling technique was requiredwas required Both saline wetted and dry sterile cotton swabs were Both saline wetted and dry sterile cotton swabs were

considered:considered: Wet cotton swabs were determined to be most effective Wet cotton swabs were determined to be most effective

for obtaining the largest sample of microorganismsfor obtaining the largest sample of microorganisms Microorganisms adhere more readily to wet surfacesMicroorganisms adhere more readily to wet surfaces

A swab and streak method was used to inoculate the agar A swab and streak method was used to inoculate the agar plates plates


To achieve the second objective a method of differentiating To achieve the second objective a method of differentiating Staphylococcus aureusStaphylococcus aureus was needed: was needed: Differential mediums and assays were used:Differential mediums and assays were used:

The gram stain was used to differentiate gram negative organisms The gram stain was used to differentiate gram negative organisms from gram positive organismsfrom gram positive organisms

The catalase assay was used to differentiate Staphylococci (positive The catalase assay was used to differentiate Staphylococci (positive result) from Streptococci (negative result)result) from Streptococci (negative result)

Blood Agar was used to differentiate Blood Agar was used to differentiate S. aureusS. aureus (positive result) from (positive result) from S. epidermis S. epidermis (negative result)(negative result)

Mannitol Salt Agar was used to differentiate Mannitol Salt Agar was used to differentiate S. aureusS. aureus (positive (positive result) from result) from S. epidermis S. epidermis (negative result)(negative result)

The CoAgulase assay was used to differentiate The CoAgulase assay was used to differentiate S. aureusS. aureus (positive (positive result) from result) from S. epidermis S. epidermis (negative result)(negative result)


Day 1Day 1 Made Mannitol Salt AgarMade Mannitol Salt Agar Autoclaved and cooled mediumAutoclaved and cooled medium

Day 2Day 2 Poured Mannitol Salt Agar platesPoured Mannitol Salt Agar plates

Day 3Day 3 Obtained Trypticase Soy Agar (TSA) platesObtained Trypticase Soy Agar (TSA) plates Obtained a package of sterile cotton swabs, and a tube of diluted salineObtained a package of sterile cotton swabs, and a tube of diluted saline Swabbed 7 objects:Swabbed 7 objects:

Bathroom sink faucet (1st floor)Bathroom sink faucet (1st floor) Bathroom (interior) doorknob (1st floor)Bathroom (interior) doorknob (1st floor) Micro bench sink faucet (Room x)Micro bench sink faucet (Room x) Front door handle—Micro buildingFront door handle—Micro building Handicapped door button—Micro buildingHandicapped door button—Micro building Computer mouse in labComputer mouse in lab Stair rail (1st floor) Stair rail (1st floor)

Detailed MethodsDetailed Methods

Day 3Day 3 (cont.) (cont.) Swabbing method used:Swabbing method used:

Dipped tip of sterile swab into salineDipped tip of sterile swab into saline Swabbed 1 of 7 objectsSwabbed 1 of 7 objects Struck inoculated swab on sterile agar plate with zigzag motionStruck inoculated swab on sterile agar plate with zigzag motion A new swab was used for each plateA new swab was used for each plate 4 plates (2 TSA and 2 Mannitol Salt Agar) were used for each 4 plates (2 TSA and 2 Mannitol Salt Agar) were used for each

objectobject Discarded the swabDiscarded the swab

Incubated all plates at 37°C for 48 hoursIncubated all plates at 37°C for 48 hours

Detailed Methods (cont.)Detailed Methods (cont.)

Day 4Day 4 Observed growth of different colony types on TSA platesObserved growth of different colony types on TSA plates Observed growth of colonies on Mannitol Salt Agar platesObserved growth of colonies on Mannitol Salt Agar plates

Observed fermentationObserved fermentation Photographed certain colonized platesPhotographed certain colonized plates Counted and recorded different types of coloniesCounted and recorded different types of colonies Selected different types of colonies from each Mannitol Salt Selected different types of colonies from each Mannitol Salt

Agar plateAgar plate Struck the selected colonies on (new) Mannitol Salt Agar Struck the selected colonies on (new) Mannitol Salt Agar

plates, on (new) TSA plates, and on (new) Blood Agar plates, on (new) TSA plates, and on (new) Blood Agar platesplates

Incubated all plates at 37°C for 24 hoursIncubated all plates at 37°C for 24 hours


Day 5Day 5 Observed Mannitol Salt Agar plates Observed Mannitol Salt Agar plates

Observed fermentationObserved fermentation Observed TSA platesObserved TSA plates Observed Blood Agar platesObserved Blood Agar plates

Observed hemolysisObserved hemolysis Performed catalase assay on pure Performed catalase assay on pure

colonies isolated from Mannitol Salt Agar platescolonies isolated from Mannitol Salt Agar plates Performed gram stain on pure colonies isolated from Mannitol Salt Agar Performed gram stain on pure colonies isolated from Mannitol Salt Agar

platesplates Performed CoAgulase assay on certain pure colonies isolated from Mannitol Performed CoAgulase assay on certain pure colonies isolated from Mannitol

Salt Agar platesSalt Agar plates Bactistaph latex 150 testBactistaph latex 150 test Photographed relevant resultsPhotographed relevant results

Day 6Day 6 Observed results from CoAgulase assay Observed results from CoAgulase assay


Day 3Day 3 Saline was used: Saline was used:

To maintain highest degree of sterilityTo maintain highest degree of sterility Since bacteria adhere more readily to wet surfaces than to Since bacteria adhere more readily to wet surfaces than to

dry surfacesdry surfaces In a diluted form so growth of non-salt tolerant organisms In a diluted form so growth of non-salt tolerant organisms

was uninhibitedwas uninhibited A new swab was used for each plate to reduce the risk of A new swab was used for each plate to reduce the risk of

contamination by organisms not found on objects of interestcontamination by organisms not found on objects of interest TSA plates were used:TSA plates were used:

As a control As a control To determine the different types of organisms on objects of To determine the different types of organisms on objects of

interestinterest

Detailed Rationale Behind MethodsDetailed Rationale Behind Methods

Detailed Rationale (cont.)Detailed Rationale (cont.) Day 3Day 3 (cont.) (cont.)

Mannitol Salt Agar plates were used:Mannitol Salt Agar plates were used: To isolate To isolate Staphylococcus aureus Staphylococcus aureus from objects of interest from objects of interest

Staphylococcus aureus Staphylococcus aureus is a salt tolerant organism that grows on is a salt tolerant organism that grows on Mannitol Salt Agar while other non-salt tolerant organisms will not Mannitol Salt Agar while other non-salt tolerant organisms will not growgrow

All plates were incubated at 37°C for 48 hours:All plates were incubated at 37°C for 48 hours: 37°C is in the optimal growth temperature range for organisms that 37°C is in the optimal growth temperature range for organisms that

could be found on objects of interestcould be found on objects of interest 48 hours is in the optimal growth time range for organisms that could 48 hours is in the optimal growth time range for organisms that could

be found on objects of interestbe found on objects of interest 4 plates (2 TSA and 2 Mannitol Salt Agar) were used:4 plates (2 TSA and 2 Mannitol Salt Agar) were used:

To safeguard from errorTo safeguard from error If an error occurred with one “set” (1 TSA and 1 Mannitol Salt Agar If an error occurred with one “set” (1 TSA and 1 Mannitol Salt Agar

plate) results could be obtained from another “set” (theoretically plate) results could be obtained from another “set” (theoretically void of error) void of error)

Detailed Rationale (cont.)Detailed Rationale (cont.)

Day 4Day 4 Different colonies from each TSA plate were struck on (new) Different colonies from each TSA plate were struck on (new)

TSA plates to confirm that colonies selected were pure and TSA plates to confirm that colonies selected were pure and different from other colonies on the platedifferent from other colonies on the plate

Struck colonies from Mannitol Salt Agar on (new) Mannitol Struck colonies from Mannitol Salt Agar on (new) Mannitol Salt Agar plates to isolate pure colonies for further tests and Salt Agar plates to isolate pure colonies for further tests and to confirm that colonies isolated were to confirm that colonies isolated were Staphylococcus aureusStaphylococcus aureus

Staphylococcus aureusStaphylococcus aureus ferments Mannitol producing a ferments Mannitol producing a yellow zone surrounding colonyyellow zone surrounding colony

Detailed Rationale (cont.)Detailed Rationale (cont.) Day 4 Day 4 (cont.)(cont.)

Struck colonies from Mannitol Salt Agar on (new) TSA Struck colonies from Mannitol Salt Agar on (new) TSA plates as a controlplates as a control

Isolated colonies were struck on Blood Agar to confirm Isolated colonies were struck on Blood Agar to confirm that isolated colonies were that isolated colonies were Staphylococcus aureusStaphylococcus aureus

Staphylococcus aureusStaphylococcus aureus has has -hemolysis on Blood Agar-hemolysis on Blood Agar


Day 5Day 5 Catalase test was performed to:Catalase test was performed to:

Confirm that cultures from Mannitol Salt Agar plates were Confirm that cultures from Mannitol Salt Agar plates were Staphylococci (positive) not Streptococci (negative) Staphylococci (positive) not Streptococci (negative)

Indicating that cultures were Indicating that cultures were Staphylococcus aureusStaphylococcus aureus Gram stain was performed to:Gram stain was performed to:

Confirm that cultures from Mannitol Salt Agar plates were gram Confirm that cultures from Mannitol Salt Agar plates were gram positive not gram negativepositive not gram negative

Indicating that cultures were Indicating that cultures were Staphylococcus aureusStaphylococcus aureus Confirm that bacteria colonized on Mannitol Salt Agar plates formed Confirm that bacteria colonized on Mannitol Salt Agar plates formed

clusters not chainsclusters not chains Indicating that cultures were Indicating that cultures were Staphylococcus aureusStaphylococcus aureus


Day 5 Day 5 (cont.)(cont.) Bacti Staph Latex 150 test was performed to:Bacti Staph Latex 150 test was performed to:

Confirm that isolated colonies tested positive not Confirm that isolated colonies tested positive not

negative for agglutinationnegative for agglutination Indicating that the cultures were Indicating that the cultures were Staphylococcus Staphylococcus

aureusaureus CoAgulase assay was performed to:CoAgulase assay was performed to:

Confirm that isolated colonies were CoAgulase positive Confirm that isolated colonies were CoAgulase positive

not CoAgulase negativenot CoAgulase negative Indicating that the cultures were Indicating that the cultures were Staphylococcus Staphylococcus

aureusaureus

Expected ResultsExpected Results

It was expected that:It was expected that:

Numerous types of microorganisms would live Numerous types of microorganisms would live on the tested objects on the tested objects

Staphylococcus aureus Staphylococcus aureus is found on some is found on some human hands and would therefore be present human hands and would therefore be present on some of the tested objectson some of the tested objects

ResultsResults

FindingsFindings

Summary of FindingsSummary of Findings

Relationship of findings to expectationsRelationship of findings to expectations

TSA plate 1 was inoculated with microorganisms TSA plate 1 was inoculated with microorganisms from the bathroom sink faucet:from the bathroom sink faucet: 7 small white colonies grew7 small white colonies grew 8 large white colonies grew8 large white colonies grew

TSA plate 2 was inoculated with microorganisms TSA plate 2 was inoculated with microorganisms from the bathroom sink faucet:from the bathroom sink faucet: 16 small white colonies grew16 small white colonies grew 31 large white colonies grew31 large white colonies grew

Mannitol Salt Agar plate 1 was inoculated with Mannitol Salt Agar plate 1 was inoculated with microorganisms from the bathroom sink faucet:microorganisms from the bathroom sink faucet: 2 small white colonies grew2 small white colonies grew

Mannitol Salt Agar plate 2 was inoculated with Mannitol Salt Agar plate 2 was inoculated with microorganisms from the bathroom sink faucet:microorganisms from the bathroom sink faucet: No growthNo growth

FindingsFindings

TSA plate 1 was inoculated with microorganisms from TSA plate 1 was inoculated with microorganisms from the computer mouse:the computer mouse: No growthNo growth

TSA plate 2 was inoculated with microorganisms from TSA plate 2 was inoculated with microorganisms from the computer mouse:the computer mouse: 1 small white colonies grew1 small white colonies grew 1 medium white colonies grew1 medium white colonies grew

Mannitol Salt Agar plate 1 was inoculated with Mannitol Salt Agar plate 1 was inoculated with microorganisms from the computer mouse:microorganisms from the computer mouse: 2 small white colonies grew2 small white colonies grew 3 large peaked colonies grew3 large peaked colonies grew

Mannitol Salt Agar plate 2 was inoculated with Mannitol Salt Agar plate 2 was inoculated with microorganisms from the computer mouse:microorganisms from the computer mouse: No growthNo growth

Findings (cont.)Findings (cont.)

TSA plate 1 was inoculated with microorganisms TSA plate 1 was inoculated with microorganisms from the stair rail:from the stair rail: No growthNo growth

TSA plate 2 was inoculated with microorganisms TSA plate 2 was inoculated with microorganisms from the stair rail:from the stair rail: No growthNo growth

Mannitol Salt Agar plate 1 was inoculated with Mannitol Salt Agar plate 1 was inoculated with microorganisms from the stair rail:microorganisms from the stair rail: 1 small white colony grew1 small white colony grew 1 large colony with yellow zone grew1 large colony with yellow zone grew

Mannitol Salt Agar plate 2 was inoculated with Mannitol Salt Agar plate 2 was inoculated with microorganisms from the stair rail:microorganisms from the stair rail: No growthNo growth


TSA plate 1 was inoculated with microorganisms TSA plate 1 was inoculated with microorganisms from the handicapped button:from the handicapped button: 1 small yellow colony grew1 small yellow colony grew

TSA plate 2 was inoculated with microorganisms TSA plate 2 was inoculated with microorganisms from the handicapped button:from the handicapped button: 1 small white colony grew1 small white colony grew

Mannitol Salt Agar plate 1 was inoculated with Mannitol Salt Agar plate 1 was inoculated with microorganisms from the handicapped button:microorganisms from the handicapped button: No growthNo growth

Mannitol Salt Agar plate 2 was inoculated with Mannitol Salt Agar plate 2 was inoculated with microorganisms from the handicapped button:microorganisms from the handicapped button: No growthNo growth


TSA plate 1 was inoculated with microorganisms TSA plate 1 was inoculated with microorganisms from front door knob:from front door knob: 33 small yellow colonies grew33 small yellow colonies grew 1 medium white colony grew1 medium white colony grew

TSA plate 2 was inoculated with microorganisms TSA plate 2 was inoculated with microorganisms from the front door knob:from the front door knob: 1 small white colony grew1 small white colony grew

Mannitol Salt Agar plate 1 was inoculated with Mannitol Salt Agar plate 1 was inoculated with microorganisms from the front door knob:microorganisms from the front door knob: No growthNo growth

Mannitol Salt Agar plate 2 was inoculated with Mannitol Salt Agar plate 2 was inoculated with microorganisms from the front door knob:microorganisms from the front door knob: No growthNo growth


TSA plate 1 was inoculated with microorganisms TSA plate 1 was inoculated with microorganisms from bathroom door knob:from bathroom door knob: 3 small yellow colonies grew3 small yellow colonies grew 1 small white colony grew1 small white colony grew 1 medium white colony grew1 medium white colony grew

TSA plate 2 was inoculated with microorganisms TSA plate 2 was inoculated with microorganisms from the bathroom door knob:from the bathroom door knob: 7 small white colonies grew7 small white colonies grew 9 large white colonies grew9 large white colonies grew

Mannitol Salt Agar plate 1 was inoculated with Mannitol Salt Agar plate 1 was inoculated with microorganisms from the bathroom door knob:microorganisms from the bathroom door knob: 2 medium colonies with yellow zones grew2 medium colonies with yellow zones grew 2 large peaked colonies grew2 large peaked colonies grew

Mannitol Salt Agar plate 2 was inoculated with Mannitol Salt Agar plate 2 was inoculated with microorganisms from the bathroom door knob:microorganisms from the bathroom door knob: No growthNo growth


TSA plate 1 was inoculated with microorganisms TSA plate 1 was inoculated with microorganisms from lab sink:from lab sink: No growthNo growth

TSA plate 2 was inoculated with microorganisms TSA plate 2 was inoculated with microorganisms from the bathroom door knob:from the bathroom door knob: No growthNo growth

Mannitol Salt Agar plate 1 was inoculated with Mannitol Salt Agar plate 1 was inoculated with microorganisms from the bathroom door knob:microorganisms from the bathroom door knob: 1 small white colony grew1 small white colony grew

Mannitol Salt Agar plate 2 was inoculated with Mannitol Salt Agar plate 2 was inoculated with microorganisms from the bathroom door knob:microorganisms from the bathroom door knob: No growthNo growth


A Mannitol Salt Agar plate was inoculated with A Mannitol Salt Agar plate was inoculated with microorganisms from the bathroom door handle:microorganisms from the bathroom door handle: Growth and fermentation on Mannitol plateGrowth and fermentation on Mannitol plate Gram positive rodsGram positive rods

Snapping replication was observedSnapping replication was observed Catalase positiveCatalase positive

A Mannitol Salt Agar plate was inoculated with A Mannitol Salt Agar plate was inoculated with microorganisms from the bathroom sink:microorganisms from the bathroom sink: Growth and fermentation on Mannitol plateGrowth and fermentation on Mannitol plate Gram positive cocci organized in grape like clustersGram positive cocci organized in grape like clusters Catalase positiveCatalase positive


A Mannitol Salt Agar plate was inoculated with A Mannitol Salt Agar plate was inoculated with microorganisms from the stair rail:microorganisms from the stair rail: Growth and fermentation on Mannitol plateGrowth and fermentation on Mannitol plate Gram positive rods Gram positive rods

Snapping replication was observedSnapping replication was observed Catalase negativeCatalase negative

A Mannitol Salt Agar plate was inoculated with A Mannitol Salt Agar plate was inoculated with microorganisms from the computer mouse:microorganisms from the computer mouse: Growth and fermentation on Mannitol plateGrowth and fermentation on Mannitol plate Gram positive rods Gram positive rods

Snapping replication was observedSnapping replication was observed Catalase positiveCatalase positive


A Blood Agar plate was inoculated with A Blood Agar plate was inoculated with microorganisms from the bathroom door handle:microorganisms from the bathroom door handle: Growth on Blood AgarGrowth on Blood Agar ββ-hemolysis -hemolysis

A Blood Agar plate was inoculated with A Blood Agar plate was inoculated with microorganisms from the bathroom sink:microorganisms from the bathroom sink: Growth on Blood AgarGrowth on Blood Agar ββ -hemolysis -hemolysis

A Blood Agar plate was inoculated with A Blood Agar plate was inoculated with microorganisms from the stair rail:microorganisms from the stair rail: Growth on Blood AgarGrowth on Blood Agar ββ-hemolysis -hemolysis

A Blood Agar plate was inoculated with A Blood Agar plate was inoculated with microorganisms from the computer mouse:microorganisms from the computer mouse: Growth on Blood AgarGrowth on Blood Agar αα-hemolysis-hemolysis


Microorganisms isolated from the objects Microorganisms isolated from the objects

exhibited a variety of phenotypes when grown on exhibited a variety of phenotypes when grown on

TSA plates:TSA plates: Small white bacterial coloniesSmall white bacterial colonies Small yellow bacterial coloniesSmall yellow bacterial colonies Medium white bacterial coloniesMedium white bacterial colonies Large white bacterial coloniesLarge white bacterial colonies

The phenotypes above indicate that a very diverse The phenotypes above indicate that a very diverse

bacterial population is present on the tested objectsbacterial population is present on the tested objects This data supports the first hypothesis that This data supports the first hypothesis that

nnumerous types of microorganisms would live on umerous types of microorganisms would live on

tested objectstested objects

Summary of Findings Summary of Findings

Microorganisms isolated from the:Microorganisms isolated from the: Stair railStair rail Computer mouseComputer mouse Bathroom door handleBathroom door handle

Are suspected to be Cornyebacteria since:Are suspected to be Cornyebacteria since: They undergo snapping They undergo snapping

replicationreplication Form “Chinese letters”Form “Chinese letters” Are gram positive rodsAre gram positive rods

This was not hypothesizedThis was not hypothesized

Summary of Findings (cont.) Summary of Findings (cont.)

Microorganisms isolated from the bathroom sink Microorganisms isolated from the bathroom sink are suspected to be are suspected to be Staphylococcus aureusStaphylococcus aureus The samples are strongly suspected to be The samples are strongly suspected to be

Staphylococcus aureus Staphylococcus aureus since:since: They are gram positive cocci seen in grape-like They are gram positive cocci seen in grape-like

clustersclusters Are catalase and CoAgulase positiveAre catalase and CoAgulase positive Have Have ββ-hemolysis-hemolysis Ferment MannitolFerment Mannitol

These phenotypes are identical These phenotypes are identical to those exhibited by to those exhibited by Staphylococcus aureusStaphylococcus aureus

This supports the second hypothesis: This supports the second hypothesis: Staphylococcus aureus Staphylococcus aureus is found on human hands is found on human hands and would therefore be present on some of the and would therefore be present on some of the tested objectstested objects

Summary of Findings (cont.)Summary of Findings (cont.)

DiscussionDiscussion Description of Description of Staphylococcus aureusStaphylococcus aureus Why Why Staphylococcus aureusStaphylococcus aureus was expected to was expected to

be foundbe found Incidence of disease Incidence of disease Virulence of Virulence of Staphylococcus aureusStaphylococcus aureus Comments on protocolComments on protocol Comments on resultsComments on results Comments on overall significance of projectComments on overall significance of project

Description of Description of Staphylococcus Staphylococcus aureusaureus

PhenotypePhenotype Gram positive cocciGram positive cocci Found in pairs, chains, or grapelike-clustersFound in pairs, chains, or grapelike-clusters Produces heat stable enterotoxinProduces heat stable enterotoxin Salt tolerantSalt tolerant Ferments MannitolFerments Mannitol Catalase positiveCatalase positive CoAgulase PositiveCoAgulase Positive

HabitatHabitat AirAir DustDust SewageSewage Environmental surfacesEnvironmental surfaces 50% of humans (higher in health professionals)50% of humans (higher in health professionals) FoodsFoods

Poultry and egg productsPoultry and egg products Egg, tuna, potato, and chicken saladsEgg, tuna, potato, and chicken salads Milk and dairy productsMilk and dairy products

Description of Description of Staphylococcus Staphylococcus aureusaureus (cont.) (cont.)

Expected to findExpected to find Staphylococcus aureus Staphylococcus aureus various various surfaces throughout the microbiology building where surfaces throughout the microbiology building where the transient flora from many peoples’ hands has been the transient flora from many peoples’ hands has been transferred. One of the places swabbed was the inside transferred. One of the places swabbed was the inside bathroom door handle, where hopefully only people bathroom door handle, where hopefully only people with freshly washed hands are touching. Unfortunately, with freshly washed hands are touching. Unfortunately, this is not always the case, and a diverse population of this is not always the case, and a diverse population of bacteria were isolated from the door handle. Someone bacteria were isolated from the door handle. Someone who fails to wash his or her hands upon exiting the who fails to wash his or her hands upon exiting the restroom is unlikely to remember to wash them before restroom is unlikely to remember to wash them before eating or preparing food for another person. Thus, if eating or preparing food for another person. Thus, if S. S. aureusaureus were found on the locations tested it could hold were found on the locations tested it could hold strong ramifications for general human cleanliness, and strong ramifications for general human cleanliness, and subsequently, health.subsequently, health.

Why Staphylococcus aureus was Why Staphylococcus aureus was expected to be foundexpected to be found

Staphylococcus aureusStaphylococcus aureus is a component of the normal is a component of the normal flora for 50% of all peopleflora for 50% of all people

Carriers of Carriers of Staphylococcus aureusStaphylococcus aureus transfer the bacteria transfer the bacteria to every touched object to every touched object

Regardless of hand washingRegardless of hand washing In proper growth conditions the bacteria will propagate In proper growth conditions the bacteria will propagate

on objects such as those testedon objects such as those tested As As Staphylococcus aureusStaphylococcus aureus contaminated objects are contaminated objects are

used, bacteria are transferred to a users transient floraused, bacteria are transferred to a users transient flora Staphylococcus aureusStaphylococcus aureus was isolated on tested objects was isolated on tested objects

Thus, hand washing does not preclude the transfer of Thus, hand washing does not preclude the transfer of Staphylococcus aureusStaphylococcus aureus to food to food

Why finding Staphylococcus aureus Why finding Staphylococcus aureus was probablewas probable

The incidence of illness is difficult to pinpoint due The incidence of illness is difficult to pinpoint due

to a number of reasonsto a number of reasons

Poor response from victims during interviewsPoor response from victims during interviews

Misdiagnosis (symptoms are very similar to those of Misdiagnosis (symptoms are very similar to those of

Bacillus cereusBacillus cereus toxin) toxin)

Inadequate collection of lab samplesInadequate collection of lab samples

Improper lab examinationImproper lab examination

Incidence of diseaseIncidence of disease

Causes staphyloenterotoxicosis (food poisoning)Causes staphyloenterotoxicosis (food poisoning)

Operates by toxin, not colonizationOperates by toxin, not colonization

IDID5050 – 1.0 microgram – 1.0 microgram

Onset of illness is rapid and varies based on:Onset of illness is rapid and varies based on:

Amount of food ingestedAmount of food ingested

Amount of toxin present in foodAmount of toxin present in food

Individual susceptibilityIndividual susceptibility

General health of victimGeneral health of victim

Virulence of Staphylococcus Virulence of Staphylococcus aureusaureus

Symptoms:Symptoms:

NauseaNausea

VomitingVomiting

Abdominal crampingAbdominal cramping

HeadacheHeadache

Changes in pressure and blood ratesChanges in pressure and blood rates

Average recovery time for mild case:Average recovery time for mild case:

2-3 days2-3 days

Virulence of Staphylococcus Virulence of Staphylococcus aureus (cont.)aureus (cont.)

TreatmentTreatment

RestRest

FluidsFluids

Medicines to calm stomachMedicines to calm stomach

Hospitalization/Intravenous therapy for more severe Hospitalization/Intravenous therapy for more severe

cases (usually elderly or infants)cases (usually elderly or infants)


PreventionPrevention Wash hands and under nails vigorously and oftenWash hands and under nails vigorously and often Do not prepare food with an eye or nose infectionDo not prepare food with an eye or nose infection Do not serve food to others with open woundsDo not serve food to others with open wounds Keep food preparation areas sanitaryKeep food preparation areas sanitary Store cooked food in wide, shallow containers and Store cooked food in wide, shallow containers and

refrigeraterefrigerate Do not leave food out for long periods of time Do not leave food out for long periods of time

Keep hot foods hot (above 140 degrees F)Keep hot foods hot (above 140 degrees F) Keep cold foods cold (40 degrees F or lower) Keep cold foods cold (40 degrees F or lower)


Comments on ProtocolComments on Protocol

Method of multiple plate inoculation was successfulMethod of multiple plate inoculation was successful By using 4 plates for each object tested it allowed for By using 4 plates for each object tested it allowed for

confirmation of resultsconfirmation of results Saline wetted swab and streak inoculation method Saline wetted swab and streak inoculation method

was successful:was successful: Isolated colony growth occurredIsolated colony growth occurred

Testing and differential media:Testing and differential media: CatalaseCatalase CoAgulaseCoAgulase Mannitol Mannitol BloodBlood

Comments on ResultsComments on Results

Comments on ResultsComments on Results Found numerous colonies resembling Found numerous colonies resembling

Corynebacteria, a Gram-Positive rod generally found Corynebacteria, a Gram-Positive rod generally found in soilin soil

Methylene blue staining did not reveal metachromatic Methylene blue staining did not reveal metachromatic granules, however not all species exhibit this traitgranules, however not all species exhibit this trait

This finding is consistent with concept of bacteria found on This finding is consistent with concept of bacteria found on unwashed handsunwashed hands

Unable to identify specific strain of Corynebacteria isolated, Unable to identify specific strain of Corynebacteria isolated, since many of the organisms can not be typed easily. since many of the organisms can not be typed easily. Although there have been significant advances in PCR Although there have been significant advances in PCR technology, this technology was not available.technology, this technology was not available.

Isolate from bathroom sink faucet is indicated by Isolate from bathroom sink faucet is indicated by tests to be tests to be Staphylococcus aureusStaphylococcus aureus

Comments on overall significance of Comments on overall significance of projectproject

This project aims to raise public awareness that This project aims to raise public awareness that

pathogenic microorganisms are present on pathogenic microorganisms are present on

numerous objects touched prior to and after numerous objects touched prior to and after

hand washinghand washing

ReferencesReferences

Boyce, J., Pittet, D. (2002). “Guideline for Hand Hygiene in Health-Care Settings” 1 April 2006. Morbidity and Mortality Weekly Report, 51-RR16. 1-44 <http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5116a1.htm>

CDC. Outbreak of community-associated methicillin-resistant Staphylococcus aureus skin infections---Los Angeles County, California, 2002--2003. Morbidity and Mortality Weekly Report 2006;52:88. <http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5512a1.htm>

U.S. Food and Drug Administration. “Staphylococcus aureus.” 1992. Food borne Pathogenic Microorganisms and Natural Toxins Handbook. <http://www.cfsan.fda.gov/~mow/chap3.html>

ReferencesReferences

Rollins, David M. "Corynebacterium Summary." Rollins, David M. "Corynebacterium Summary." BSCI 424 — BSCI 424 — Pathogenic Microbiology.Pathogenic Microbiology. Aug. 2000. Dept. of Cell Bio. & Aug. 2000. Dept. of Cell Bio. & Molecular Genetics, UMD. 2 May 2006 Genetics, UMD. 2 May 2006 <http://www.life.umd.edu/classroom/bsci424/PathogenDescri<http://www.life.umd.edu/classroom/bsci424/PathogenDescriptions/Corynebacterium.htm>.ptions/Corynebacterium.htm>.

Madigan, Michael T., and John M. Martinko. Madigan, Michael T., and John M. Martinko. Brock Biology of Brock Biology of MicroorganismsMicroorganisms. 11th ed. London: Pearson Prentice Hall, . 11th ed. London: Pearson Prentice Hall, 2006. 386-387.2006. 386-387.

Sneath, Peter H., James T. Staley, and Stanley T. Williams, Sneath, Peter H., James T. Staley, and Stanley T. Williams, eds. eds. Bergey's Manual of Systematic Bacteriology.Bergey's Manual of Systematic Bacteriology. Vol. 2. Vol. 2. Baltimore: William and Wilkins, 1986. 1266-1280.Baltimore: William and Wilkins, 1986. 1266-1280.

Transient flora on hands as a vehicle of transmission to food for Staphylococcus aureus Elissa Redmiles and Lucy Erickson.

Documents

food preparation

food hygiene

food spoilage

approach overall approach

present slide

washed hands

objects staphylococcus

isolation of bacteria