Microbial investigation of hard surfacing materials


Morton, L.H.G.; Mitchell, A.F.; Vaughan, F.

Biodeterioration of constructional materials Proceedings of the summer meeting of the Biodeterioration Society, Delft, Netherlands, 18-19 September 1986: 129-140

1987


An account is presented of a survey which was undertaken to investigate the nature and extent of the microbial flora of in-service ceramic tile surfaces and their grout joints. A list of taxa isolated is presented. The effect upon the resident flora of cleansing these surfaces with 1% hypochlorite is fully documented. A series of laboratory experiments are described in which selected tile surfaces and grout jointing compounds were deliberately infected with a flora representative of that encountered in the field. Results are presented which show the effect of cleansing with 1% hypochlorite upon this infected flora. The results of the investigations show that the wide range of natural flora of ceramic surfaces and the deliberately infected flora can be reduced by washing with 1% hypochlorite.

MICROBIAL
INVESTIGATION
OF
HARD
SURFACING
MATERIALS
L.H.G.
MORTON"
A.F.
MITCHELL'
and
F.
VAUGHAN
2
(1)
School
of
Applied
Biology
(2)
Buildings
Adhesives
Ltd
Lancashire
Polytechnic
Stoke
on
Trent
Preston,
Staffordshire,
U.K.
Lancs,
U.K.
SUMMARY
An
account
is
presented
of
a
survey
which
was
undertaken
to
investigate
the
nature
and
extent
of
the
microbial
flora
of
in-service
ceramic
tile
surfaces
and
their
grout
joints.
A
list
of
taxa
isolated
is
presented.
The
effect
upon
the
resident
flora
of
cleansing
these
surfaces
with
1%
hypochlorite
is
fully
documented.
A
series
of
laboratory
experiments
are
described
in
which
selected
tile
surfaces
and
grout
jointing
compounds
were
deliberately
infected
with
a
flora
representative
of
that
encountered
in
the
field.
Results
are
presented
which
show
the
effect
of
cleansing
with
1%
hypochlorite
upon
this
infected
flora.
The
results
of
the
investigations
show
that
the
wide
range
of
natural
flora
of
ceramic
surfaces
and
the
deliberately
infected
flora
can
be
reduced
by
washing
with
1%
hypochlorite.
Introduction
The
extent
to
which
any
hard
surface
may
become
contaminated
by
micro-organisms
will
depend
upon
a
number
of
factors
including
the
nature
of
the
surface,
the
nature
of
the
contaminating
micro-
organisms
and
the
nature
of
the
in-service
environment.
When
considering
the
nature
of
any
surface
which
may
become
contaminated
the
physical,
chemical
and
biological
properties
of
that
surface
should
be
taken
into
account.
The
physical
nature
of
a
surface
relates
to
the
texture
of
the
surface.
A
rough
surface
will
have
a
greater
surface
area
and
may
have
niches
where
micro-
organisms
may
lodge
and
flourish.
The
chemical
nature
of
a
surface
relates
to
the
pH
of
the
surface
(excessively
alkaline
surfaces
.are
not
conducive
to
microbial
growth)
or
to
the
presence
of
chemicals
in
the
surface
material
or
leaching
from
it,
which
are
toxic
to
micro-organisms.
The
biological
nature
of
the
surface
relates
to
whether
the
surface
;
is.
a
biologically
active
or
inert
material,
i.e.
one
that
promotes
colonization
by
virtue
of
its
organic
nature,
or
one
that
is
normally
inert
until
it
becomes
coated
with
nutritive
material.
129
Micro-organisms
which
contaminate
hard
surfaces
will
vary
not
only
in
size
and
in
shape
but
perhaps
more
importantly
in
the
nature
of
their
external
surface
or
coat.
For
example,
there
may
be
specialised
organelles
present
to
enhance
adhesion
to
surfaces
or
gelatinous
extra-cellular
exudates
may
be
present
which
are
responsible
for
the
adhesion
of
the
micro-organism
to
the
surface.
Bacteria
are
known
to
stick
to
hard
surfaces
by
means
of
a
mass
of
tangled
fibres
of
polysaccharides
that
extend
from
the
bacterial
surface
and
form
a
felt-like
glycocalyx
surrounding
an
individual
cell
or
colony
of
cells
(Costerton
et
al
1978).
Ingold
(1984)
describes
methods
by
which
fungal
spores
may
adhere
to
surfaces,
these
include:
spore
masses
produced
in
slime,
production
of
extra
cellular
exudates
by
the
spores,
and
the
morphological
modification
of
the
spores
to
produce
structures
which
function
as
'anchors'.
The
major
factors
concerning
the
nature
of
the
in-service
environment
are:
The
humidity
of
the
air
coming
into
contact
with
the
surface,
the
microbial
loading
of
the
air
coming
into
contact
with
the
surface,
the
standard
of
cleanliness
of
the
work
force
in
the
environment,
the
nature
and
frequency
of
cleaning
survices.
Ceramic
surfaces
along
with
metal
and
glass
are
considered
to
be
biologically
inert
surfaces.
However,
Hoffman
et
al
(1973)
record
contamination
of
steel
fitments
beside
a
bottle
washing
plant
whilst
Nagamuttu
(1967)
reports
mould
growth
on
glass
used
in
optical
equipment..
Smith
and
Nadim
(1983)
report
that
surfaces
can
be
contaminated
by
the
air
passing
over
then
especially
when
the
air
has
a
high
relative
humidity
and
may
be
contaminated
with
substances associated
with
human
activity,
for
example:
volatile
hydrocarbons
(from
nearby
machinery),
dust,
skin
tissue,
cigarette
smoke,
exhaled
droplets,
traces
of
fats
and
salts
from
'fingerprints'
during
handling.
This
activity
results
in
a
film
of
nutrients
and
condensed
water
which
allows
the
growth
of
bacteria
and
fungi.
The
installations
visited
during
this
survey
are
listed
in
Table
1.
They
represent
domestic,
industrial,
social;
agricultural
and
medical
environments
where
ceramic
tiled
wall
surfaces
are
in
common
use.
Traditionally
the
isolation
of
micro-organisms
from
surfaces
was
undertaken
using
the
agar
sausage
technique
of
Cate
(1963,
1965).
In
this
technique
the
freshly
exposed
surface
of
nutrient
agar
set
in
the
form
of
a
sausage
is
pressed
onto
the
surface
to
be
sampled,
it
is
then
sliced
aseptically
into
a
petri-dish
where
it
is
incubated
with
the
exposed
surface
uppermost.
Greig
(1966)
describes
the
use
of
this
method
in
the
comparison
of
preparation
surfaces
and
cleaning
methods
in
the
meat
industry.
Bridson
(1969)
outlines
the
criteria
used
to
recognise
the
levels
of
contamination.
The
method
has
advantages
over
swabbing
and
scraping
techniques
for
surface
sampling.
However,
the
'sausage'
has
been
replaced
by
the
contact
plate
technique.
130
Collins
(1964)
in
his
account
of
"Dishwashing
Kitchen
Container
and
Surface
Sanitation",
reviews
the
methods
for
counts
on
working
surfaces,
floors
and
walls
as
follows:
(i)
Swab
Counts,
this
method
involves
the
use
of
alginate
(soluble)
swabs
which
are
applied
to
an
area
within
a
sterilized
template.
The
swab
is
dissolved
in
sterile
diluent,
and
organisms
are
estimated
by
conventional
microbiological
methods.
(ii)
Direct
surface
counts,
this
uses
the
agar
sausage
techinque.
(iii)
The
Scotch
Tape
Method,
in
this
technique
clean
tape
is
pressed
onto
the
surface
to
be
sampled,
the
tape
is
then
pressed
onto
the
surface
of
an
agar
plate
which
is
incubated.
Survey
Work
Throughout
the
survey
work
the
contact
plate
technique
was
used
to
sample
the
tiled
surfaces
of
the
installations
visited.
Contact
plates
are
petri
dishes
modified
for
ease
of
handling.
The
surface
of
the
agar
in
the
plates
is
exposed,
pressed
against
the
surface
to
be
sampled,
the
lid
replaced
and
the
plate
incubated
at
an
appropriate
temperature.
Contact
plates
are
described
fully
in
Hall
and
Hartnett
(1964).
Malt
extract
agar
was
dispensed
into
those
plates
used
to
isolate
fungi,
nutrient
agar
was
used
for
the
isolation
of
bacteria.
Figure
1
shows
the
sampling
pattern
adopted
during
this
work,
where
A-D
represent
the
grout.joints
sampled
and
1-4
represent
the
central
tile
areas
samples.
This
sampling
routine
was
carried
out
on
undisturbed
tiles
at
the
installations
visited
(Table
1).
The
tiles
were
then
cleansed
with
a
proprietory
brand
of
sodium
hypochlorite
at
a
working
concentration
of
1%
v/v.
Each
area
sampled
was
cleansed
with
paper
tissues
well
soaked
with
the
cleansing
solution.
After
approximately
half
an
hour
when
the
surface
had
dried,
the
sampling
routine
was
repeated.
Finally
the
surfaces
were
re-cleansed.
The
plates
were
returned
to
the
laboratory
where
they
were
incubated.
Nutrient
agar
plates
(for
bacteria)
were
incubated
at
37
°
C
under
aerobic-
and
anaerobic
conditions
for
48
hrs.
The
plates
containing
malt
agar
(for
fungi)
were
incubated
at
25
°
C
for
up
to
7
days.
A
wide
range
of
bacteria
and
fungi
were
isolated
as
a
result
of
this
investigation.
Fungi
were
identified
by
bringing
them
into
pure
culture
and
then
by
microscopic
examination
of
fruiting
structures.
Selected
bacteria,
as
pure
cultures,
were
identified
by
using
the
API
20E
system
of
biochemical
tests.
Table
2
shows
the
micro-organisms
isolated
during
this
investigation.
Table
3
shows
the
effect
of
cleansing
with
1%
hypochlorite
upon
the
resident
flora
of
ceramic
tile
surfaces.
Table
4
shows
the
effect
of
cleansing
with
1%
hypochlorite
upon
the
resident
flora
of
ceramic
tile
grout
joints.
Table
5
shows
the
effect
of
cleansing
with
1%
hypochlorite
upon
the
anaerobic
bacterial
population
of
ceramic
'tile
surfaces
and
their
grout
joints.
131,
TILE
SURFACES
GROUT
JOINTS
2
4
TABLE
1,
INSTALLATIONS
VISITED
BETWEEN
JANUARY
AND
MARCH
1985
A
DOMESTIC
BATHROOM
A
DOMESTIC
SHOWER
A
PITHEAD
SHOWER
AREA
A
DOMESTIC
KITCHEN
AN
INDUSTRIAL
KITCHEN
(FOOD
PROCESSING
FACTORY)
A
MILKING
PARLOUR
A
DAIRY
(RAW
MILK
COLLECTION
ND
STORAGE
AREA)
A
HOSPITAL
OPERATING
THEATRE
A
VETERINARY
SURGERY
OPERATING
THEATRE
A
PUBLIC
CONVENIENCE
FIGURE
1,
STANDARD
SAMPLING
PATTERN
FOR
IN-SERVICE
TILE
SURFACES
AND
GROUT
JOINTS
REPRESENTATION
OF
AREA
SAMPLED
(FOUR
REPLICATES
PER
SITE)
132
TABLE
2:
MICRO-ORGANISMS
ISOLATED
DURING
THE
SURVEY
FUNGI
ISOLATED
DURING
THE
SURVEY
PHYCOMYCETES
Mucorales
Mucoraceae
Circinella
simplex
Van
Tieghem
ASCOMYCETES
Sphaeriales
Chaetomiaceae
Chaetomium
sp
DEUTEROMYCETES
Sphaeropsidales
Sphaerioidaceae
Phoma
sp
Phoma
Rerbarum
Westend
Pyrenochaeta
sp
MONILIALES
DEMATIACEAE
Aureobasidium
puZtulans
(de
Barry)
Arnaud
Stachybotrye
atra
Corda
Cladosporium
sp
Cladosporium
cladosporiodes
(Fresen)
de
Vries
Cladosporium
herbarum
(Persoon)
link
Stemphylium
piriforme
Bonorden
TUBERCULARIACEAE
Fusarium
sp
Epicoccum
nigrum
link
YEAST:
Rhodotorula
sp
Moniliaceae
Aspergillus
sP
Aspergillus
flavus
Link
Aspergillus
ochraceous
Wilhelm
Aspergillus
nidulans
(Eidam)
Winter
Aspergillus
flavipes
Bainer
and
Sartory
Acremonium
stricturnW.
Cams
Cephalosporium
sp
Cephalosporium
asperum
Marchal
Penicillium
spp
Penicillium
brevicompactum
Dierckx
Penicillium
funiculoaum
Than.
Penicillium
decumbens
Than.
Penicillium
frequentans
Westling
Verticillium
lateritium
Berkerly
Verticillium
sulphurelZum
Saxerdo
Nematogonium
sp
A
REPRESENTATIVE
SAMPLE
OF
BACTERIA
ISOLATED
DURING
THE
SURVEY
Escherichia
coil
7044
204
Proteus
sp
0
024
121
Bacillus
spp
7
523
00,
0
222
005
Bacillus
spp
000
001
755
147
110
775
Streptococcus
sp
417
230
023
Arthrobaoter
sp
267
510
411
Micrococcus
sp
000
000
613
TABLE
3,
THE
EFFECT
OF
CLEANSING
WITH
11
SODIUM
HYPOCHLORITE
UPON
THE
RESIDENT/CONTAMINATING
FLORA
OF
CERAMIC
TILE
SURFACES
FUNGI
BACTERIA
SITE
VISITED
UNCLEANSED
CLEANSED
UNCLEANSED
CLEANSED
DOMESTIC
BATHROOM
16
0
2
0
DOMESTIC
SHOWER
2
1 1
0
PITHEAD
SHOWER
3
0
62
0
DOMESTIC
KITCHEN
35
0
700
0
INDUSTRIAL
KITCHEN
1
1
375
0
MILKING
PARLOUR
175
8
600
350
DAIRY
2
2
18
10
OPERATING
THEATRE
6
3
18
0
VETERINARY
SURGERY
1
0
1
0
PUBLIC
CONVENIENCE
1
1
41
1
NUMBERS
REPRESENT
COLONY
FORMING
UNITS/CONTACT
PLATE
.20
CM
2
133
TABLE
4,
THE
EFFECT
OF
CLEANSING
WITH
1%
SODIUM
HYPOCHLORITE
UPON
THE
RESIDENT/CONTAMINATING
FLORA
OF
CERAMIC
TILE
GROUT
JOINTS
SITE
VISITED
FUNGI
UNCLEANSED
CLEANSED
BACTERIA
UNCLEANSED
CLEANSED
DOMESTIC
BATHROOM
53
23
31
2
DOMESTIC
SHOWER
4
1
20
0
PITHEAD
SHOWER
6
0
50
0
DOMESTIC
KITCHEN
27
0
600
0
INDUSTRIAL
KITCHEN
3
0
-
230
6
MILKING
PARLOUR
88
10
1
350
DAIRY
20
0
33
10
OPERATING
THEATRE
11
2
55
7
VETERINARY
SURGERY
0
0
8
0
PUBLIC
CONVENIENCE
1
0
32
2
NUMBERS
ARE
'COLONY
FORMING
UNITS'/CONTACT
PLATE
s20
CM2
*
-
COLONIES
TOO
NUMEROUS
TO
COUNT
TABLE
5,
THE
EFFECT
OF
CLEANSING
WITH
1%
HYPOCHLORITE
UPON
THE
ANAEROBIC
BACTERIAL
POPULATION
OF
CERAMIC
TILE
SURFACES
AND
GROUT
JOINTS
TILED
SURFACE
GROUT
JOINTS
SITE
VISITED
UNCLEANSED
CLEANSED
UNCLEANSED
CLEANSED
DOMESTIC
BATHROOM
1
1
5
3
DOMESTIC
SHOWER
0
0
1
0
PITHEAD
SHOWER
0
0
0
0
DOMESTIC
KITCHEN
475
9
230
0
MILKING
PARLOUR
70
25
85
70
DAIRY
9
0
20
6
OPERATING
THEATRE
0
0
0
0
VETERINARY
SURGERY
0
0
0
0
PUBLIC
CONVENIENCE
14
0
72
0
NUMBERS
REPRESENT
COLONY
FORMING
UNITS/CONTACT
PLATE
.20
CM
2
134
Ceramic
Tile
Surfaces
Except
for
certain
venues
notably
the
domestic
kitchen,
the
milking
parlour
and
the
industrial
kitchen
general
levels
of
microbial
contamination
were
low.
The
effect
of
cleansing
upon
these
surfaces
was
quite
marked
resulting
in
an
almost
complete
reduction
of
the
flora
in
most
cases
except
the
milking
parlour
where
the
resident
population
was
reduced
by
over
50%.
(Table
3).
Grout
Joints
Numbers
of
bacteria
encountered
were
quite
low
with
the
exception
of
the
domestic
kitchen
the
milking
parlour
and
the
industrial
kitchen.
The
effect
of
cleansing
was
very
marked
resulting
in
a
reduction
in
the
population
except
for
the
heavily
contaminated
milking
parlour
site,
where
350
cfu/20
cm
were
recorded
after
cleansing.
None
of
the
sites
could
be
considered
to
have
high
levels
of
fungal
contamination
even
in
service.
However,
the
milking
parlour,
the
domestic
bathroom
and
domestic
kitchen
recorded
the
highest
incidence
of
contamination.
The
effect
of
cleansing
was
again
very
marked
with
the
domestic
bathroom
showing
the
least
reduction
in
population
at
around
50%.
(Table
4).
Anaerobic
bacterial
populations
encountered
during
the
survey
show
the
domestic
kitchen
having
the
highest
incidence
of
contamination
on
the
tile
surfaces
and
on
the
grout
lines.
The
effect
of
cleansing
is
recorded
in
Table
5.
Laboratory
Work
In
a
series
of
laboratory
experiments
tiled
surfaces
and
their
grout
lines
were
contaminated
with
a
flora
representative
of
that
encountered
in
the
field.
The
surfaces
were
then
cleansed
and
the
contamination
levels
re-assessed.
Two
types
of
tile
were
tested
namely
a
WHITE
GLAZED
tile
measuring
108
x
108
x
4
mm
and
a
GREY
tile
measuring
150
x
150
x
12
mm.
The
tiles
were
mounted
onto
tamped
concrete
blocks
with
BAL
Rapid
Set.
The
grout
joints
employed
are
listed
in
Table
6.
The
organisms
used
in
this
work
are
listed
in
Table
7.
They
were
prepared
as
a
mixed
suspension
in
ste5ile
1/4
strength
Ringers
solution
at
approximately
1
x
10
6
cfu/
cm
.
The
tile
test
panels
were
'housed'
in
perspex
incubation
chambers
set
at
25
o
C
with
a
working
RH
of
90-95%.
Plate
1.
The
spore
suspension
was
sprayed
onto
the
surface
and
grout
joints
of
the
test
panels
which
were
then
incubated.
Fig.
2
outlines
the
sampling,
cleansing
and
re-sampling
procedures.
Tables
8,
9,
10
and
11
show
the
effect
of
cleansing
upon
contaminated
tile
surfaces
and
grout
joints.
135'
TABLE
6,
GROUTS
TESTED
DURING
THE
LABORATORY
WORK
DESCRIPTION
OF
GROUT
BAL
EPDXY
GROUT
6
MM
Two-part
epoxide
resin
grouting
material
providing
an
impervious
joint.
BAL
EPDXY
GROUT
3
MM
BAL
BAL
FIX
AND
GROUT
GROUT
3
MM
3
MM
Read.,
-rinsed,
thin-bed,
water-based
,
aLryi,
adhesive
and
grouting
compound.
Cement-based
v
all
tile
product.
BAL
GROUT
FOR
FLOORS
6
MM
Cement-based
floor
tile
product.
BAL
SUPER
GROUT
3
MM
Ready-mixed
,
water
repellent
acrylic
grout.
BAL
SPAN
12
MM
Cement-based
grout
for
use
in
wide
joints.
BROWN
BAL
GROUT
6
MM
Brown
cement-based
wall/floor
tile
grout.
TABLE
7,
ORGANISMS
USED
IN
LABORATORY
WORK
Aureobasidium
pullulans
(de
Barry)
Arnaud
Penicillium
funiculosum
Thom.
Stachybotrys
atra
Corda.
Rhodotorula
glutinis
Bacillus
sp.
147
110
775
Escherichia
coli
NC1B
6571
ATCC
9144
Staphylococcus
aureus
Dui
iii
2
B
4
B
B
PY/
a
B
r.
Perspex
Incubation
Chambers
FIGURE
2,
FLOW
DIAGRAM
OF
LABORATORY
INVESTIGATION
PROCEDURE
INOCULATION
7
DAYS
>
SAMPLE
>
CLEANSE
>
RESAMPLE
7
DAYS
>
FURTHER
1x10
6
cFu/cm
3
AFTER
1
HR,
RESAMPLE
136
TABLE
8.
THE
EFFECT
OF
CLEANSING
UPON
TILE
SURFACES
AND
GROUT
JOINTS
CONTAMINATED
UNDER
LABORATORY
CONDITIONS
WHITE
GLAZED
TILE/BACTERIAL
POPULATIONS
CONTAMINATED
GROUT
TILE
GROUT
TYPE
JOINTS
BAL
EPDXY
GROUT
9
8
6
mm
BAL
EPDXY
GROUT
10
9
3
MM
BAL
FIX
&
GROUT
10
9
3
MM
BAL
GROUT
3
MM
9
10
BAL
GROUT
FOR
9
10
FLOORS
6
mm
BA
3
L
mm
SUPER
GROUT
8 8
BAL
SPAN
12
mm
9
8
BROWN
BAL
GROUT
8
a
6
MM
NUMBERS
REPRESENT
0-100%
COVER
OF
CONTACT
PLATE
IN
10%
INCREMENTS.
TABLE
9.
THE
EFFECT
OF
CLEANSING
UPON
TILE
SURFACES
AND
GROUT
JOINTS
CONTAMINATED
UNDER
LABORATORY
CONDITIONS
WHITE
GLAZED
TILE/FUNGAL
POPULATIONS
GROUT
TYPE
CONTAMINATED
TILE
GROUT
JOINTS
CLEANSED
(1
HR)
TILE
GROUT
JOINTS
RESAMPLED
(7
DAYS)
TILE
GROUT
JOINTS
BAL
EPDXY
GROUT
6
mm
10
10
1
3
2
3
BAL
EPDXY
GROUT
3
mm
8
10
1
1
3
5
BAL
FIX
&
GROUT
9
10
7
1
3
.2
3
MM
BAL
GROUT
10
10
1
1
1
1
3
mm
BAL
GROUT
7
6
6
5
4
3
FOR
FLOORS
6
MM
BAL
SUPER
GROUT
10
9
1
2
7
6
3
MM
BAL
SPAN
12
MM
10
10
1
2
1
3
BROWN
BAL
GROUT
10
10
4
6
4
6
6
mm
CLEANSED
(1
HR)
TILE
GROUT
JOINTS
RESAMPLED
(7
DAYS)
TILE
GROUT
JOINTS
1
2
1 1
3
4
1
1
1
3
2
2
4
7
5
5
3
4
3
4
3
5
2
1
4
3
5
2
3 3
1
3
NUMBERS
REPRESENT
0-100%
COVER
OF
CONTACT
PLATE
IN
10%
INCREMENTS.
137
TABLE
1G.
THE
EFFECT
OF
CLEANSING
UPON
TILE
SURFACES
AND
GROUT
JOINTS
CONTAMINATED
UNDER
LABORATORY
CONDITIONS
GREY
TILE/BACTERIAL
POPULATIONS
GROUT
TYPE
CONTAMINATED
TILE
GROUT
JOINTS
CLEANSED
(1
HR)
TILE
GROUT
JOINTS
RESAMPLED
(7
DAYS)
TILE
GROUT
JOINTS
BAL
6
EP
DXY
GROUT
m
8
9
6
5
1
4
BAL
EPDXY
GROUT
9
10
8
8
2
2
3
MM
BAL
FIX
&
GROUT
10
9
5
4
2
5
3
MM
BM:
GROUT
7
8
4
5
7 7
3
MM
BAL
GROUT
FOR
7
8
2
3
6
4
FLOORS
6
MM
BAL
SUPERGROUT
mm
8
6
5
5
6
2
BAL
SPAN
12
mm
7
8
2
2
2
5
BROWN
BAL
GROUT
8
9
5
4
6
5
6
mm
NUMBERS
REPRESENT
0-100%
COVER
OF
CONTACT
PLATES
IN
10%
INCREMENTS.
TABLE
11,
THE
EFFECT
OF
CLEANSING
UPON
TILE
SURFACES
AND
GROUT
JOINTS
CONTAMINATED
UNDER
LABORATORY
CONDITIONS
GREY
TILE/FUNGAL
POPULATIONS
GROUT
TYPE
CONTAMINATED
TILE
GROUT
JOINTS
CLEANSED
(1
HR)
TILE
GROUT
JOINTS
RESAMPLED
(7
DAYS)
TILE
GROUT
JOINTS
BA
L
L
'
EP
DXY
EPDXY
GROUT
BAL
EPDXY
GROUT
3
mm
BA
3
L
FIX
&
GROUT
mm
BAL
GROUT
3
mm
BAL
GROUT
FOR
FLOORS
6
MM
BAL
3
SUPERGROUT
mm
BAL
SPAN
12
MM
BROWN
m
GROUT
6
m
.
8
9
10
7
7
8
7
10
'
9
10
9
8
8
6
8
10
6
8
5
4
2
5
2
7
'
5
-
8
4
5
3
5
2
8
1
2
2
7
6
6
2
5
4
2
5
7
4
2
5
7
NUMBERS
REPRESENT
0-100%
COVER
OF
CONTACT
PLATE
IN
10%
INCREMENTS,
138
White
glazed
tiles
and
grout
joints
The
tiles
surfaces
and
grout
joints
showed
high
levels
of
bacterial
contamination.
(Table
8).
Sampling
one
hour
after
cleansing
showed
a
very
marked
reduction
in
the
level
of
bacterial
growth.
Sampling
one
week
after
cleansing
showed
levels
of
contamination
below
the
initial
contamination
levels
in
all
cases.
A
similar
pattern
emerged
for
fungal
populations.
(Table
9).
The
data
shows
that
supression
of
initial
growth
persisted
during
the
second
seven
day
period
of
the
experiment.
Howeyer,
there
is
evidence
of
fungal
recovery
in
the
test
with
BAL
Supergrout
3
mm,
and
BAL
Epoxygrout
3
mm.
Grey
tiles
and
grout
joints
Samples
taken
1
hr
after
cleansing
showed
that
a
reduction
of
the
bacterial
and
fungal
populations
had
occurred.
This
was
not
well
marked
in
BAL
Epoxy
grout
3
mm.
However,
after
the
second
seven
day
period
this
also
showed
a
marked
reduction
in
the
population.
Same
evidence
of
bacterial
recovery
was
recorded
with
BAL
GROUT
3
mm
on
tile
surfaces
and
grout
joints
and
with
BAL
SPAN
12
mm,
in
the
grout
joints.
(Tables
10
and
11).
As
a
result
of
this
investigation
it
can
be
seen
that
a
wide
range
of
fungi
and
bacteria
occur
on
ceramic
tile
surfaces,
and
that
contamination
levels
vary
from
venue
to
venue.
By
cleansing
with
hypochlorite
bacterial
and
fungal
contamination
could
be
considerably
reduced
in
most
cases
where
contamination
occured
or
was
induced.
REFERENCES
BRIDSON,
E.Y.
(1969).
Isolation
of
surface
micro-organisms
with
the
agar
slice
Technique.
in
Isolation
Methods
for
Microbiologists
No.
3.
(Eds).
Shapton,
B.A.
and
Gould,
G.W.
Academic
Press
pp.
135-140.
CATE,
L.
TEN
(1963)Eine
einfache
and
schelle
bacteriologische
Betrieb
in
Fleisch
verarbeitenden
mittles
Agar-
"Wursten"
in
Rilsan
Kunstadarm.
Fleishwirtschaft,
15,
483.
CATE,
L.
TEN
(1965).
A
note
on
a
simple
method
of
bacteriological
sampling
by
means
of
agar
sampling.
J.
Appl.
Bact.,
28,
221.
Collins,
C.H.
(1964).
Dishwashing,
Kitchen,
Container
and
Surface
Sanitation,
in
Microbiological
Methods,
Butterworths,
pp
292-295.
COSTERTON,
J.W.,
GEESEY,
G.G.
AND
CHENG,
K.J.
(1978).
How
Bacteria
Stick.
Sci.
Am.
238,
86-95.
GREIG,
J.R.
(1966).
An
improved
method
of
surface
bacteriological
sampling
in
food
premises.
Pub.
Health.
Inspect.
75,
377.
HALL,
L.B.
AND
HARTNETT,
M.J.
(1964).
Measurement
of
the
Bacterial
Contamination
on
Surfaces
in.Hospitals.
Public
Health
Reports
79,
1021-1024.
139
HOFFMAN,
E.,
HILL,
R.K.
AND
SARACZ,
J.
(1973).
Fungus
resistant
paints
for
breweries
and
the
humid
tropics.
Journal
of
the
Oil,
Colour
and
Chemical
Associates,
56(1),
17-27.
.
Ingold,
C.T.
(1984).
The
Biology
of
Fungi.
Fifth
Edition.
Hutchinson.
NEGAMUTTU,
S.
(1967).
Moulds
on
optical
glass
and
control
measures.
International
Biodeterioration
Bulletin,
3
(1),
1-3.
SMITH,
R.N.
AND
NADIM,
L.M.
(1983).
Fungal
Growth
on
Inert
Surfaces.
in
Biodeterioration
5.
(eds)
T.A.
Oxley
and
S.
Barry.
John
Wiley
and
Sons
Ltd.
pp
538-547.
ACKNOWLEDGEMENTS
The
authors
gratefully
acknowledge
the
cooperation
of the
individuals
and
organisations
who
willingly
granted
access
to
the
various
in-service
sites
visited.
140