Environmental Organism Transfer
Tasha Sturm 1
1 Cabrillo College, 6500 Soquel Dr, Aptos, Ca
95003, USA
Abstract
There are numerous bacteria, yeast and molds living
in the surrounding environment that can be transferred to other organisms via
contact. Shoes and hands were either swabbed or pressed onto TSA agar
plates and incubated at 37 degree's C for 48 hrs, then room temperature for 72
hrs, then plates kept at refrigerated temperature for up to a week.
Different incubation temperatures allowed different species of bacteria, yeast,
mold to grow from one sample. Organisms normally found on the body would
grow at 370 C while room temperature and refrigerated temperatures
yielded environmental yeast and molds. As seen in the images below Bacillus spp., a common spore forming
soil bacteria is the majority of growth seen through out the samples and grew
well at warm incubation temperatures while growth of the colorful yeast and
molds took longer to grow and were less abundant. Everything seen in these
images are naturally occurring environmental organism and are normally
harmless.
Introduction
Over the past several years a focus on hand hygiene and
exposure to environmental organisms has been highlighted in the media as to
what is “normal flora’ and what is not [1, 2, 3]. There are numerous bacteria, yeast and molds living in the
environment that can be transferred to other organisms, humans as well as the things
we wear or carry, via contact. Most organisms are not actively growing
but have developed mechanisms to survive in harsh environments or at least
remain in a “holding pattern” until they find good growing condition. A common adaptation is spore formation seen in
molds and bacterial species such as Bacillus spp. and Clostridium spp.
[5, 6]. In the following images objects such as shoes and hands were
either swabbed or pressed onto TSA agar plates and incubated at 37 degree's C
for 48 hr, then room temperature for 72 hrs, then plates kept at refrigerated
temperature for up to a week. Different incubation temperatures allowed
different species of bacteria/yeast/mold to grow from one sample, either shoe
swab or hand print. Organisms normally found on the body, (Staphylococcus spp., Micrococcus spp.) would grow at 370C
while room temperature (210 C) and refrigerated temperatures (40C)
yielded colorful environmental yeast and molds.
Key words: hand washing, soil bacteria, immune
system
Shoe Swabs
 |
| Image 1: |
Image 2: Image 1&2 Unknown Bacillus spp. seen from swabbing the bottom of a shoe. Colonies are
dry, matt and rhizoid characteristic of Bacillus
spp.
 |
|
Image 3: Shoe tread
imprint with numerous growth of numerous Bacillus
spp., white, rhizoid colonies and small mucoid Bacillus spp. in lower right corner
|
Image 5: Image 4 and 5 Unknown Bacillus spp., possible B. amyloliquefaciens, from swabbing the bottom of a shoe. Colonies were mucoid with swarming finger like growth
 |
|
Image 6: Shoe swab with fungal growth, center with clear zone around
growth indicating possible antibacterial properties
|
 |
| Image 7: Shoe swab showing a mix of bacterial and fungal (yeast) growth. |
Handprints:
 |
| Image 8: Handprint done in colder wet weather. Note: branching swirling Bacillus mycodies seen on thumb and palm, absent in Image 8 |
 |
|
Image 9: Handprint
done is warm dry weather: Note large colonies are a Bacillus spp. and differ from those found in image 7
|
Unwashed Hand Compared to Washed Hand
 |
|
Image 10: unwashed handprint with close up
of large bacterial colony, Bacillus
mycodies, in left quadrent of
the plate.
|
 |
| Image 11: This is the same hand from Image 10 after hand washing with soap and water |
Discussion
As seen in the images above Bacillus spp., a common spore forming soil bacteria, is the
majority of growth seen through out the samples, both hand and shoe swabs, and
grew well at warm incubation temperatures while growth of the colorful yeast
and moulds took longer to grow and were less abundant. Bacillus
spp. seen in the Images 1-5, 7 represent the majority of growth seen on the
bottom of shoe swabs/prints. Not
an unexpected result since Bacillus spp.
is a common spore forming bacteria found in soil [4]. Several morphologies are seen from dry, matt, rhizoid and
spreading to mucoid spreading with finger like projections. Although not common occasionally a
fungal colony is seen, Image 6, with this one exhibiting potential antibiotic
properties. Image 7 does show a
variety of unknown yellow organisms, possible yeast.
With hand prints (Image 8 & 9) it is interesting to note
that there is a different mix of organisms at different times of the year with
the colder wet weather yielding a less colorful print compared to the warm
weather print yielding a colorful mix of orange and yellow yeast and
bacteria. Also interesting is the
morphology difference with Bacillus spp.
on the two plates with Bacillus mycodies
appearing more commonly on the cold weather plates. Before and after hand washing prints were done as well. As seen in images 10 & 11 the hand
washed with soap and water yielded a print with much less diversity with mainly
normal body flora growing on the plate.
The unwashed hand had environmental bacterial present with numerous
larger Bacillus spp. present as well as yellow yeast.
Conclusion
Over the past several years hand washing and bacterial
awareness has become more prevalent in the media. These images simply illustrate that numerous environmental organisms
can hitch a ride on the objects they come in contact with whether it be a shoe
or a hand. It is important to
understand that although the images represent an unseen world it is not one
that needs to be feared. Everything
seen in these images are naturally occurring environmental organisms that are
harmless to most healthy people and we need exposure to organisms to build a healthy
immune system [7, 8]. Although we rely on organism exposure it also serves as
reminder to wash before eating to prevent possible disease as well.
References:
4. Conn, JH.
The Most abundant Group of Bacteria in Soil. ASM Bacterial Reviews. 257-275
5. Paredes-Sabja D, Setlow P, Sarker MR. Germination of spores
of Bacillales and Clostridiales species: mechanisms and proteins involved. Trends Microbiol. 2011;19:85–94. [PubMed]
6. Tan S Irene, Ramamurthi S Kumaran.
Spore
formation in Bacillus subtilis. Environ Microbiol Rep. 2014 Jun; 6(3):
212–225
7. Hooper Lora V,
Littman Dan R, Macpherson Andrew J. Interactions Between the Microbiota
and the Immune System. Science 06 Jun 2012:
8. Davis Mark. Immune systems of healthy adults 'remember' germs to which
they’ve never been exposed, Stanford study finds.
https://med.stanford.edu/news/all-news/2013/02/immune-systems-of-healthy-adults-remember-germs-to-which-theyve-never-been-exposed-stanford-study-finds.html
*Correspondence
to:
Tasha
Sturm
Cabrillo
College
6500
Soquel Dr
Aptos,
CA 95003
USA
PH:
831-479-6318
Email:
tasturm@cabrillo.edu
Tee Shirt available at Cabrillo College Book Store(831479-6209)
Tee Shirt available at Cabrillo College Book Store(831479-6209)
Comments
Post a Comment