STAPHYLOCOCCOUS
AUREUS
Stephanie Socotch and Taylor Rathke
History of Agent - Ancient
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Discovered by Scottish surgeon Sir Alexander Ogston in
1881.
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He observed grape-like clusters under microscope
In 1884, Anton Rosenbach isolated two strains:
Staphylococcus aureus and Staphylococcus albus
By 1941 the disease was prevalent in hospitals and
many patients had died from it.
Later that year a British policeman was cured by
penicillin.
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Doctors began using the antibiotic Benzyl penicillin to cure
patients, but the Staphylococcus bacteria soon became
resistant.
History of Agent - Contemporary
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There are now several different effective antibiotics
available to treat S. aureus infections.
Most common antibiotics today: penicillin, ampicillin,
and amoxicillin.
How they work:
 They
disrupt the bacterial cell wall, cause cell leakage,
and cell death.
Interesting Factoids
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Bacteria is carried on the human skin and in the
nose
43% of all skin infections in the U.S. are the result
of one strain of MRSA (methicillin-resistant
Staphylococcus aureus)
Most MRSA used to be hospital-acquired, but now,
roughly 75% of MRSA is community-acquired (the
patient is infected outside the hospital)
An estimated 12 million patients are at risk for
developing an S. aureus infection each year in the
U.S.
Example of Staphylococcus
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During a soccer game, Stephanie ended up sliding on the turf of the
field she was playing on and acquired a large abrasion on her leg.
She made sure to wash it with warm, soapy water and cover it with
a bandage. Seven days later she woke up with and noticed her leg
was extremely itchy. When she took a look she found that her leg
was covered in red bumps all around the scratch site. She suspected
it was Staph, so she decided to call the doctor when the bumps
became puss-filled later that day. When she met with the doctor he
diagnosed her with a Staphylococcus infection. He took a sample of
one of the bumps and sent it to the lab to make sure he was correct.
He prescribed her sulfamethoxazole, which is an antibiotic that
treats for a variety of Staph and Strep infections. She took two a
day for ten days and her infection cleared right up! She was so
relieved that she didn’t infect anyone else while she had staff.
Description of S. aureus bacteria
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Size: 0.5-1.5 microns
Shape: Spherical
Arrangement: Grape-like clusters
Motility: Non-motile
Staining Characteristics: Gram-Positive
Culture Staining Characteristics: Facultative anaerobes
that grow by aerobic respiration or by fermentation
that produce lactic acid; usually form large yellow
colonies on growth media
Metabolic/Growth Characteristics: Optimum growth is
30-37 degrees Celsius.
Virulence Factors and Functions
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They have surface proteins that promote colonization of host tissues.
Invasins (protein produced by bacteria that helps them penetrate
into mammalian cells) that promote bacterial spread in tissues.
Examples are leukocidin, kinases, hyaluronidase)
Surface factors that inhibit phagocytic engulfment such as capsules.
Immunological disguises (Protein A, coagulase)
Membrane-damaging toxins that lyse eukaryotic cell membranes
(hemolysins, leukotoxin, leukocidin)
Exotoxins that damage host tissues and create symptoms of disease
Description of Staphylococcus
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It is spherical, Gram-positive, immobile and forms
chains of grape-like clusters. Staphylococci are
facultative anaerobes that use aerobic respiration,
or fermentation producing lactic acid.
Incubation time: The incubation period is variable;
most commonly 4-10 days.
Affects in Tissues/Organs
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S. aureus can get into the body and resist
phagocytosis. If in the bloodstream, it can spread
throughout the body and lead to circulatory
collapse. This can affect people with lung diseases,
which can lead to abscess formation in the lungs.
The infection of heart valves can lead to heart
failure. In the bones it can cause severe
inflammation (oseomyelitis).
Outward Symptoms
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Infected area will be tender, swell and will see signs
of redness. Skin lesions will from like boils or styes.
Skin infections can form a crusting of the skin.
Mode of Transmission
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Transmitted by direct or indirect contact with a
person infected, contaminated surfaces and medical
equipment, or an open wound coming into contact
with contaminated area.
Diagnostic Process
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The doctor should closely examine the lesions to
perform a physical exam.
Bacteria must be observed under the microscope
and then isolated so it can be tested for a specific
strain.
Methods of Prevention and Treatment
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Prevention: hand washing, keeping wounds covered,
good hygiene, and keeping personal items clean.
Treatment: Antibiotics (such as sulfamethoxazole)
Statistics of S. aureus in the US
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Estimated hospital infections each year: 1,200,000
Deaths resulting from MRSA: 19,000
Country with the highest outbreak of MRSA: United
Kingdom
Country with lowest outbreak: Netherlands
In 2005, there was an estimated 14 million
outpatient healthcare visits for suspected S. aureus
skin and soft tissue infections in the United States.
Why is it an important disease to
study?
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S. aureus is a major public health problem and can
be spread easily through indirect or direct contact.
This drug is easily transmittable in hospital settings;
meaning people acquiring these infections already
have a compromised immune system. S. aureus can
also quickly become resistant to antibiotics, so it’s
important we have multiple ways to kill off these
bacteria.
References
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Anthony, A. (2010, August 10). Hospital-acquired Methicillin Resistant Staphylococcus Aureus. Retrieved
October 30, 2012, from MicrobeWiki website: http://microbewiki.kenyon.edu/index.php/Hospitalacquired_Methicillin_Resistant_Staphylococcus_Aureus_(MRSA)
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Klevens. (2007). MRSA Surveillance . Retrieved October 27, 2012, from Centers for Disease Control and
Prevention website: http://www.cdc.gov/mrsa/statistics/mrsa-surveillance-summary.html
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This website provided a historical look on how the S. aureus infection and how it affected the population at the time.
Nelson, M. (n.d., December). Who Discovered Staph Infections? Retrieved October 27, 2012, from eHow
Health website: http://www.ehow.com/about_5173303_discovered-staph-infections_.html
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This source described many statistics about the S. aureus bacteria infections in the United States and in other countries
throughout the world.
Orent, W. (2006, December). A Brief History of Staph. Retrieved October 27, from Massachusetts General
Hospital website: http://protomag.com/assets/a-brief-history-of-staph
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This website gave us the picture of the bacteria S. aureus.
This source took a look into the discovery and identification of the S. aureus infection.
Pulugurtha, S. (2011, March 30). Antibiotics for Staph Strep Infections. Retrieved October 27, 2012, from
Livestrong Foundation website: http://www.livestrong.com/article/269585-antibiotics-for-staph-strepinfections/
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This source went into detail about the various antibiotic treatments for a S. aureus infections.
References (continued)
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Some Interesting Staphylococcus aureus Factoids. (2007, March 7). Retrieved October 27,
2012, from National Geographic website:
http://scienceblogs.com/mikethemadbiologist/2007/03/07/some-interesting-staphylococcu/
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Todar, K. (2008). Staphylococcus aureus and Staphylococcal Disease. Retrieved October 27,
2012, from Online Textbook of Bacteriology website:
http://textbookofbacteriology.net/staph.html
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This source went into detail about the characteristics of the S. aureus bacteria.
Infectious Diseases - Epidemiology and Surveillance . (2007, February 10). Retrieved October
27, 2012, from Department of Health for Victoria, Australia website:
http://ideas.health.vic.gov.au/bluebook/staphylococcal.asp#mode
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This website went over six interesting factoids about the S. aureus infection.
This source went over the infection agents, the incubation period, the mode of transportation,
preventative measures, and much more information about S. aureus.
Shiel, W. C.; Stoppler, M.C. (2012, April 20). Staph Infection (Staphylococcus aureus).
Retrieved October 27, 2012, from MedicineNet, Inc. website:
http://www.medicinenet.com/staph_infection/page2.htm#what_are_the_symptoms_and_signs
_of_a_sta
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This website provided information about symptoms of a S. aureus infection and also delivered
information on how organs and tissues are affected with this infection.