SURFACE SAMPLING IS A SIGNIFICANT PROCESS FOR DETERMINING THE

presence of viable microorganisms on the surfaces of ISO Class 5 engi-

neering controls, carts, counters, walls, floors, and most importantly, the
gloved hands of compounding personnel. Proposed changes to USP
Chapter <797> refer to the sampling of surfaces, including gloved hands.
(See Figure 1.)
Measuring Microbial Bioburden
Environmental surface microbial bioburden can be measured by many dif-
ferent devices, including contact plates, swabs, and paddles, which are
commercially available containing a variety of different media. For most
applications, tryptic soy agar (TSA), supplemented with neutralizers such
as lecithin and polysorbate 80, is the most useful. It is imperative to use
media supplemented with such neutralizers to inactivate residual disinfec-
tants.
1
Polysorbate 80 neutralizes
phenols, hexachlorophene, and for-
malin; lecithin inactivates quaternary
ammonium compounds.
Contact plates can be employed to
establish and monitor the efficacy of
disinfectants, cleaning techniques,
and microbial load. Filled with agar
that forms a convex surface, these
small petri dishes are suitable for monitoring flat surfaces, such as lami-
nar-airflow workbenches (LAFWs),
floors, and walls. The plates meas-
ure 24 to 30 mm in diameter, and
are often referred to as RODAC
(Replicate Organism Detection
And Counting) plates. RODAC is
a brand name of contact plates
prepared and sold by Becton,
Dickinson and Company.
To sample an area using a contact
plate, remove the lid and gently roll
the agar surface across the sample area,
transferring any microorganisms present
on the surface onto the agar. After obtaining
the sample,
replace the lid and
clean the surface with a wipe and iso-
propyl alcohol to remove any agar
residue left by the contact plate. Then
incubate the plate at temperatures
condusive for the growth of a variety
of microorganisms.
Swabs are best suited for use on
irregular surfaces such as switches and dials, where contact plates cannot
be used. This method may either be qualitative or quantitative, depend-
ing on the type of analysis conducted.
The use of swabs requires a specific technique to ensure proper surface
sampling. As per aseptic technique, carefully remove the swab from its
tube, allowing any excess moisture to remain in the tube. Then rub the
swab across the surface using a twisting motion, and replace it in the tube.
If quantitative analysis is desired, refrigerate the tube after sampling (for
no more than 48 hours), until received by the laboratory. If qualitative
analysis is desired, incubate the tube as above and observe it for turbidity
in the medium, an indication of contamination.
Like contact plates, plastic agar paddles are layered with media and
used to sample various surfaces. They are ideal for surfaces which are dif-
ficult to reach, such as crevices between equipment. Some paddles can also
be used for air (settling-media) sampling.
Surface-testing materials may be obtained from the microbi-
ology laboratory or infection surveillance department of most
hospitals. Alternatively, these supplies are available from a num-
ber of vendors, including Becton, Dickinson and Company;
bioMrieux; Biotest Diagnostics; Millipore Corporation; Q.I.
Medical, Inc.; and Remel.
Establishing an Environmental-Monitoring Plan
Like the U.S. Food and Drug Administrations cGMPs for drugs
and medical devices, USP Chapter <797> is ambiguous regard-
ing the details of its implementation. Pharmacists must be able
to demonstrate that their sterile-preparation compounding pro-
gram is under control. Therefore, it is important to design an
environmental-monitoring plan that indicates the engineering
The Importance of
Environmental Monitoring, Part II:
Surface Testing
24
by Eric S. Kastango, RPh, MBA, FASHP
and Kym Faylor
P
h
o
t
o
c
o
u
r
t
e
s
y
o
f
R
e
m
e
l
Swabs (left) and contact plates (right and above) are necessary tools in an effective envi-
ronmental monitoring program.
P
h
o
t
o
c
o
u
r
t
e
s
y
o
f
R
e
m
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P
h
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Figure 1: Proposed USP Chapter <797> Sampling Plan for Surfaces
a
For example, each individual LAFW or barrier isolator.
b
Use a separate contact plate or swab for each of the following locations:
bottom, either side, and upper surface.
CSPs per Week
per ISO Class 5 Source
a
Minimum Interval
Between Sampling
Low- and
Medium-Risk
Levels:
High-Risk Level:
Surfaces in ISO
Class 5 Sources
a,b
:
Fingertips
of Gloves:
Fewer than 100 Zero Six months Six months
101 to 300 One to two Three months Three months
More than 300 Three or more One month One month
Environmental monitoring should be used
as an early-warning system to alert staff
when a critical aspect of the compounding
process is drifting out of control.
25
controls, sanitization practices,
process, and employees maintain
an environment with consis-
tently acceptable microbial
levels. An environmental-
monitoring plan should be
capable of detecting, in a
timely manner, an adverse
trend in microbial popula-
tions, and facilitate the iden-
tification of that trends
source(s), such as equipment
failure, sanitization practices,
personnel habits, or training defi-
ciencies, so they may be corrected
before the environment is adversely
affected. If the critical elements of
a robust environmental-monitoring
plan are performed and docu-
mented regularly, environmental
control can be easily demonstrated
and monitored.
Establishing Alert
and Action Levels
Environmental monitoring should
be used as an early-warning sys-
tem to alert staff when a critical
aspect of the compounding process
is drifting out of control. Any for-
mal environmental-monitoring plan
requires the establishment of alert
and action levels, or the threshold
numbers of viable microorganism
colony-forming units (CFUs) that
indicate a facilitys loss of control.
The absolute CFU value has limited
scientific meaning, but is used to
identify adverse trends and devia-
tions from a known baseline of
microorganisms within a controlled
environment. Acting on trends or
shifts in CFU count can prevent sig-
nificant problems that could affect
compounded sterile preparation
(CSP) quality. However, it is not
appropriate to use environmental
data (action or alert levels) as CSP
quality release checks, since a direct
cause-effect relationship does not
automatically exist between envi-
ronmental excursions and product
contamination
2
. It is also critical to
understand that environmental-
bioburden testing, especially testing
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of critical areas like ISO Class 5 workbench surfaces, should not be con-
sidered an acceptible substitute for sterility testing. For example, a nega-
tive test (absence of CFUs) on a critical surface test does not mean that the
compounded preparation is sterile
3
.
Data should be collected at evenly distributed intervals for at least one
year to establish a realistic environmental-bioburden baseline. Many vari-
ables may affect contamination levels, including seasonal variations in
temperature and humidity. For instance, warmer temperatures and higher
humidity increase operator discomfort and provide better growth condi-
tions for microbes. Outdoor contributors like construction and pollution
can also affect contamination levels, as microbes can be dispersed into the
air and carried into the facility. Another consideration is the facilitys size:
crowding in a small facility may cause operator discomfort and inappro-
priate cleanroom behavior. In addition, inappropriate cleanroom construc-
tion materials, such as non-epoxy-coated gypsum wall board and tile
flooring, can hinder effective cleaning of the controlled environment.
If action levels are exceeded, gram stain morphology can be used to
identify certain microorganisms, and can aid in detecting the source of
contamination and its remediation. (See Figure 2.)
USP Chapter <1116> indicates suggested levels for different air-cleani-
liness classifications, but does not indicate if these are alert or action lev-
els. (See Figure 3.) These levels can be used as a resource and initial guide
when establishing alert and action levels. However, actual data from your
facility should be accumulated and analyzed to establish your levels.
Conclusion
Establishing a robust environmental-monitoring plan will provide informa-
tion on the performance of the facility, including air cleanliness, temperature,
and humidity; compliance of personnel relative to garbing procedures and
movement; effectiveness of cleaning procedures; and aseptic technique and
the handling of components used in the preparation of CSPs. This inexpen-
sive quality metric can yield valuable information and identify issues before
they impact the sterility and integrity of compounded sterile preparations.
References:
1. Brummer B. Influence of possible disinfectant transfer on staphylococ-
cus aureus plate counts after agar contact sampling. Appl. Environ.
Microbiol. 1976;32:80-84.
2. PDA Special Scientific Forum on Environmental Monitoring and
Aseptic Processing. PDA Letter. 2000;11:1.
3. Stoedter W. FDAs Concept Paper on Sterile Drug Products Discussed
at PDA Annual Meeting. PDA Letter. 2003;1:1,7.
Additional Reading:
Block SS, ed. AAMI steam sterilization and sterility assurance in health
care facilities. In Disinfection, Sterilization, and Preservation. 5th ed.
Philadelphia, Pa: Lippincott Williams & Wilkins; 2000:22.
Eric Kastango, RPh, MBA, FASHP, provides expertise in aseptic process-
ing, medical-device manufacturing, and the implementation of extempo-
raneous compounding-quality systems through his New Jersey-based con-
sulting company, Clinical IQ, LLC. He is also a pharmacy surveyor for
the Accreditation Commission for Health Care, Inc.
Kym Faylor is the manager of quality assurance at Bethlehem,
Pennsylvania-based Microbiological Environments, where she has worked
for the past eight years. She is also a member of the Parenteral Drug
Association, the Biopharmaceutical Education and Training Associa-
tion, the American Society for Quality, and the Regulatory Affairs
Professionals Society.
Visit www.pppmag.com/articles.php to read
The Importance of Environmental Monitoring,
Part 1: Air Sampling.
Figure 2: CFUs and Their Probable Sources
Source: Microbiological Environments
Microorganisms
(via gram stain/
morphology)
Indication
Staphylococcus/
Micrococcus
Personnel habits or gowning problems
Gram negative rods Water condensation, leaking, aerosols
Bacillus species Dust, dirt, floor traffic, possible air handling
Molds
Influx of unfiltered air, mold from street clothing
or mold-contaminated carboard, water reservoir,
i.e. incubator humidification system
Yeast
Possible outdoor air influx; clothing-borne,
especially in late summer/ fall; possible human
contaminant
Diptheroids/
coryneforms
Poor air conditioning (leading to sweating and
personnel discharge from gowns)
Where to find it:
Becton, Dickinson and Company . . . . . . . . . . . . . . . . . . . Circle #92
or visit www.bd.com.
bioMrieux . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Circle #10
or visit www.biomerieux.com.
Biotest Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Circle #90
or visit www.biotestusa.com.
Millipore Corporation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Circle #12
or visit www.millipore.com.
Q.I. Medical, Inc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Circle #89
or visit www.qimedical.com.
Remel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Circle #14
or visit www.remel.com.
Clinical IQ, LLC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Circle #88
or visit www.clinicaliq.com.
Microbiological Environments . . . . . . . . . . . . . . . . . . . . . . Circle #85
or visit www.microbioenv.com.
Figure 3: USPs Published Levels of CFUs per Contact Plate (24 to 30 cm
2
)
ISO Class
Equipment
surfaces,
walls etc.
Floors Gloves Garb
5 3 3 3 10
7 5 10 10 20
8 N/A N/A N/A N/A
26