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Is The Prevalence of Staphylococcus aureus Increasing Among York College Students?
By: Angel Newson
Department of Biological Sciences, York College of Pennsylvania
Introduction
•Staphylococcus aureaus (S. aureus) is one of the leading
causes of bacterial infections and is the most commonly
identified multi-drug resistant pathogen in many parts of the
world including the United States. Of the 94,000 persons
infected in 2005, 19,000 died (Sampathkumar, 2007).
•S.aureus is a gram-positve bacterium frequently found in
nasal passages of healthy individuals or carried on the skin.
An average of 25% to 30% of the U.S. population is
colonized in the nose for S. aureus. Asymptomatic
colonization of S. aureus is more common than infections
(Weber, 2008). Two places where MRSA has been
identified
are
athletic
clubs
and
hospitals.
Collected 58 Nasal and 22 skin
swabs from YCP students
Growth in M-Staphylococcus
Broth
Mannitol Salt Agar Plate
Streaks
Coagulase Testing
B-Lactamase testing
2008
Characteristic
N¹
All Students
2007
58
# Of positive
(%)
18 (31.0)
102
# Of Positive
(%)
27 (26.5)
Females
43
13 (30.2)
77
21 (27.3)
Males
15
5 (33.3)
25
6 (24)
Athletics
39
12 (30.8)
51
13 (25.5)
Healthcare
21
5 (23.8)
20
5 (25)
Athletics and
Healthcare
14
5 (35.7)
7
3 (42.9)
N¹
N¹= sample size
Results
•Correlation between coagulase positive Sa nasal
samples for 2007 and 2008 showed no significant
difference (P=0.5852). An upward trend was observed
between sample years. The percentages of positive
nasal samples were 26.5% and 31% for 2007 and 2008
students, respectively.
Figure 1. Comparison of Coagulase +
and B-lactamase + S. aureus nasal
samples between individuals associated
with healthcare and athletics. Both male
and female samples are included.
•B-lactamase positive Sa skin and nasal samples were
very significant (P= 0.0037). Percentages for positive
nasal samples were 77.8% compared to 0% of skin
samples.
•The percentage of coagulase positive Sa nasal samples
(31%) showed no significant difference in comparison to
the coagulase positive Sa skin sample percentage (23%),
P= 0.5846.
•MRSA has become resistant to a majority of the Betalactam antibiotics, which target bacterial enzymes that are
critical to cell wall synthesis (McCarthy, 2003). MRSA
strains carry a gene known as mecA that is responsible for
its resistance.
•Positive results for both Coagulase positive Sa and Blactamase positive Sa were higher among female
samples.
Figure 4. Represents the process by which the presences of Blactamase enzymes break penicillin bonds. This reaction causes the
deactivation of penicillin. The inactive form is unable to kill bacteria
which ultimately increase the resistance of the microorganism. This
mechanism is one of many ways in which bacteria become resistant to
various antibiotic treatments.
•Although there was no difference between the skin
and nasal Sa coagulase tests, there was a difference
in antibiotic resistance. S. aureus from samples of
the nasal area was characteristically more resistant
than skin samples. Although some students could
potentially carry a resistant strain of S. aureus in
nasal membranes, lack of its presence on student
skins prevents spreading of the bacteria when
students are in close contact.
Conclusion
S. aureus infections have been and will continue
Figure 2. Comparison of Coagulase+ and Blactamase+ nasal samples between male and
females. The total amount of individuals positive in
each category is represented by the blue bar.
Number of Male or females are represented by the
corresponding color coded bar.
*
# of students
•Percentage variations among characteristics were
minimal. There was no difference in the percentage of
Sa coagulase positive students who participated in
athletics, healthcare affiliate, or a combination of the two
characteristics.
• The number of female samples that were
coagulase positive increased approximately 10%.
The total number of student samples for 2007 was
102. Of the 102 sampled, only 27 were coagulase
positive (26.5%). In contrast to 2007 samples, 18 of
the 58 students tested positive (36%) in 2008
samples.
This increase, however, was not
significant. There is no correlation between
healthcare and athletic affiliation, and the prevalence
of S. aureus among YCP students.
•Skin samples were similar when compared to nasal
samples tested for coagulase positive Sa. None of
the Sa skin samples tested positive for B-lactamase.
Almost all of the nasal Sa samples that were
coagulase positive also tested positive for Blactamase (14 of 18 = 78%).
•Data was recorded at each experimental phase
•Statistical analysis was conducted using Fisher’s exact testing
•There are five factors that facilitate transmission of
Community associated MRSA: Crowding, direct skin-to-skin
contact, compromised skin such as cuts or abrasions,
sharing of items or surfaces contaminated by wound
drainage, and cleanliness and hygiene (Weber, 2007).
•***Objectives***
To determine the correlation between gender,
healthcare workers, and athletes with the prevalence of
coagulase-positive S. aureus on York College Campus
To compare the prevalence of coagulase-positive S.
aureus at YCP between 2007 and 2008
To determine the antibiotic resistance of the samples by
measuring B-lactamase activity
To compare coagulase-positive S. aureus detected
from both nasal and skin samples
•The study indicates that there was no significant
difference in coagulase positive Sa prevalence
between 2007 and 2008.
Table 1. Comparison of Staphylococcus aureus prevalence among nasal samples of
York College Students between 2007 and 2008.
# of students
Community associated Methicillin-Resistant Staphylococcus
aureus (MRSA) infections have been increasing over the past
several decades. S. aureus, once know as a hospital-acquired
infection, is responsible for numerous hospitalizations
annually. Infections are caused by community-acquired or
hospital-acquired S. aureus. Nasal and skin samples from
current York College students were collected and tested for the
presence of coagulase positive S. aureus and B-lactamase
enzymes. Statistical analysis were conducted to determine the
relation between the prevalence of coagulase positive S.
aureus samples and gender, healthcare affiliation, and athletic
activity. When compared to a similar experiment conducted by
a former student in 2007, there was no significant difference
among coagulase positive S. aureus nasal samples between
2007 and 2008, although there was a slight increase. S.
aureus
B-lactamase positive nasal samples showed a
significant difference when compared to skin samples. As the
bacteria continues to spread throughout communities, the
number of individuals carrying the bacteria or infected with the
bacteria are expected to increase.
Discussion
Methods
# of students
Abstract
to rise in the immediate future. It is necessary to
assess the impact that MRSA and other staph
infections will have on local communities. It has
breached the hospital barrier and is now
potentially a threat for the entire population.
Although this current study suggest a small,
insignificant increase in the prevalence of S.
aureus at York College, additional sampling of a
larger, more diverse student population would be
ideal in measuring its presence among YCP
students.
Literature Cited
Figure 3. Comparison of nasal and skin
samples of coagulase positive S. aureus.
Positive coagulase samples were tested for
the presence of B-lactamase. None of the
coagulase positive skin samples tested
positive for B-lactamase. * indicates a
significant difference in B-lactamase positive
nasal and skin samples (p=0.0037).
•McCarthy, Michael. Resistant Bacteria Spread Through US Communities. The Lancet
2003;362(9395): 1554-1555.
•Sampathkumar, Priya. Methicillin-Resistant Staphylococcus aureus: The Latest Health
Scare. Mayo Clinic Proceedings 2007; 82(12): 1463-1467.
•Weber, Carol J. Update on Methicillin-Resistant Staphylococcus aureus (MRSA).
Journal of Urologic Nursing 2008; 28(2): 143-145.
Acknowledgments:
Carolyn Mathur, PhD, YCP Research Mentor
Jeffery Thompson, PhD, YCP Senior Thesis Instructor