Download Qualitative Analysis of the Presence of Staphylococcus aureus On

Prevalence of Staphylococcus aureus on the Door Handles of Assisted Living versus
Independent Living Resident’s Rooms in a Retirement Facility
Joseph S. Blanschan* and Carolyn F. Mathur, Department of Biological Sciences, York College of Pennsylvania
Abstract
Staphylococcus aureus (SA) is a leading cause of both nosocomial
and community-acquired infections, although little is known
about its occurrence in retirement facilities. While nasal carriage
is the most common reservoir of the bacterium, fomite reservoirs
could also be significant, and studies have shown that SA is able
to live on inanimate surfaces for several months. Elderly
individuals are particularly vulnerable to SA infection due to
lowered immunity, poor personal hygiene, and crowded living
environments, such as can occur in a retirement facility where
they may rely on others for personal care. This study compares
the occurrence of SA on assisted living (AL) versus independent
living (IL) door handles at the point of entry to each resident’s
room in a retirement facility. Door handles were swabbed (n=60),
and the swabs incubated in staphylococcus-enrichment broth. SA
was then detected by positive results in mannitol salt agar,
coagulase, and catalase tests. Antibiotic resistance was also
assessed by the presence of β-lactamase. Forty percent of AL
door handle cultures were positive for both SA and β-lactamase,
as compared to only 3.3% of the IL door handle cultures (Fishers
exact two tailed test, p = 0.0004). This study suggests that AL
resident’s rooms may require additional disinfection protocols
compared to those used in IL resident’s rooms.
Results
Methods
Assisted
door handle swabs
n=30
Independent
Door handle swabs
n=30
A
B
C
D
m. staph broth ,
incubation 48 h
Assisted
MSA plated,
incubation 24 h
Independent
Objectives
• To determine and compare the prevalence of SA
occurrence on Assisted living and Independent living
resident’s room door handles in a retirement facility.
• To compare the virulence of the SA isolates from the
two areas by measuring the presence of coagulase,
catalase and β- lactamase enzymes.
Catalase
test
β-lactamase
test
Coagulase
test
Figure 1. A) Comparison of percent positive (+) MSA results between assisted living (AL) and
independent living (IL) samples (P = 0.1154). B) Comparison of combined percent + mannitol
and + catalase results between AL and IL samples (P = 0.0092). C) Comparison of combined
percent + mannitol, + catalase and + coagulase results between AL and IL samples(P = 0.0048).
D) Comparison of combined percent + mannitol, + catalase, + coagulase and + β-lactamase
results between AL and IL samples (P = 0.0011). Fisher exact two-tailed T tests used for all
statistical analysis.
Introduction
Staphylococcus aureus (SA)
• SA is a gram positive, facultative anaerobe, that is the fourth
most common hospital acquired pathogen among older adults
in the United States (Bradley 2011).
• Over 25% of the general population are carriers for SA (Tolen
et al. 2011).
• Its effects range from minor soft-tissue infections to lifethreatening diseases such as sepsis and severe pneumonia.
• MSA media is selective for bacteria that are able to grow in
high salt concentrations and differential for organisms that are
able to ferment mannitol (Benson 2002).
• The enzymes coagulase, catalase and β-lactamase are SA
virulence factors that are also used in identification of the
bacterium.
• Catalase is an enzyme that aids in the breakdown of hydrogen
peroxide, a common by-product of metabolic reactions, to
hydrogen and water (Benson 2002).
• Coagulase has antiphagocytic properties and it is often used as
a key enzyme in the identification of SA (Benson 2002).
• β-lactamase deactivates the beta lactam ring in antibiotics,
such as penicillin, thus making the organism resistant (Bradley
2011).
Retirement Facilities
• Retirement facilities are often divided based on the level of
care required by the residents.
• Assisted living: residents require assistance with activities of
daily living (ADL’s) (i.e. dressing, bathing, and toileting).
• Independent living: residents do not require assistance with
ADL’s.
Results Summary
• Mannitol-salt agar (MSA) detected bacteria able to tolerate high salt concentrations and ferment mannitol (i.e. staphylococci and some enterococci): 70 % of AL samples were
positive, compared to 46.6 % positive IL samples (Fig. 1A, p = 0.1154).
• Positive MSA were then tested for catalase, eliminating any MSA + enterococci. AL samples were 66% positive for this combination, while only 30% of IL were positive (Fig. 1B, p =
0.0092).
• Positive MSA and catalase samples were then tested for coagulase, a virulence factor that discriminates between the virulent SA and other Staph species. AL samples were 50.0%
positive for these, compared to 13.3% of the IL samples (Fig 1C, p = 0.0048).
• Positive MSA, catalase and coagulase were tested for β-lactamase, which confers some antibiotic resistance to bacteria. Forty percent of AL samples were positive in all 4 tests,
compared to 3.33% all positive in the IL samples (Fig. 1D, p = 0.001).
Discussion
• There was a higher prevalence of virulent, β-lactamase positive SA on the surface of AL door handles when compared to IL door handles.
• The results suggest that AL resident room door handles may require additional disinfection protocols compared to those used in the IL resident areas.
• The results also suggest that the hands-on patient care associated with assisted living plus possible improper glove use following tasks such as toileting and
bathing may be a potential source of the increased levels of SA on the door handles .
• Further education in the standard precautions for glove use for caretakers may be necessary in decreasing the percentage of positive SA door handles.
Future Implications
Literature Cited
• Future plans are to implement new disinfection protocols for the door handles of
the facility and to further education in the standard precautions of glove use in
the facility.
• A random test will be conducted in order to determine if the new disinfection
procedures are effective.
Benson, H. J. (2002). The Staphylococci: Isolation and Identification. In Microbiological Applications: Laboratory Manual in General Microbiology (8th
ed., pp. 257-261). New York, NY: McGraw Hill.
Bradley, Suzanne, Thomas T. Yoshikawa, Section Editor. (2011). Staphylococcus aureus Infections and Antibiotic Resistance in Older Adults Clin Infect
Dis. (2002) 34 (2): 211-216. doi:10.1086/338150.
Tolan, Robert , MD; Chief Editor: Russell W Steele.(2011). Staphylococcus Aureus Infection .Medscape .http:/ /emedicin e.medscape .com /article
/97135 8-overview#a0101.