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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
Overall approach and rationale for Overall approach and rationale for approach (cont.)approach (cont.)
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)
Overall approach and rationale for Overall approach and rationale for approach (cont.)approach (cont.)
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
Detailed Methods (cont.)Detailed Methods (cont.)
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
Detailed Methods (cont.)Detailed Methods (cont.)
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
Detailed Rationale (cont.)Detailed Rationale (cont.)
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
Detailed Rationale (cont.)Detailed Rationale (cont.)
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
Findings (cont.)Findings (cont.)
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
Findings (cont.)Findings (cont.)
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
Findings (cont.)Findings (cont.)
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
Findings (cont.)Findings (cont.)
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
Findings (cont.)Findings (cont.)
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
Findings (cont.)Findings (cont.)
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
Findings (cont.)Findings (cont.)
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
Findings (cont.)Findings (cont.)
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)
Virulence of Staphylococcus Virulence of Staphylococcus aureus (cont.)aureus (cont.)
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)
Virulence of Staphylococcus Virulence of Staphylococcus aureus (cont.)aureus (cont.)
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>.
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