© Inštitut za sanitarno inženirstvo, 2017
International Journal of sanitary engineering researchVol. 11  No. 1/2017 S it r  Engineering Research 55
A comparison of three 
different cleaning methods 
for reducing contaminants 
on contact surfaces – a 
preliminary study
1 University of Ljubljana, Faculty of Health 
Sciences, Zdravstvena pot 5, Ljubljana, 
Slovenia
*	Corresponding author 
 Mojca Jevšnik, University of Ljubljana, 
Faculty of Health Sciences,  
Zdravstvena pot 5, Ljubljana, Slovenia  
E-mail: mojca.jevsnik@zf.uni-lj.si
Mojca Jevšnik1*, Andrej OvcA1, Peter RAspOR1 
ABsTRAcT
The aim of this study was to evaluate three different cleaning procedures 
routinely applied in processes to prevent microbiological product contamination. 
The evaluation was done in the context of their hygienic suitability and cleaning 
effectiveness according to defined surface hygiene standards. Furthermore, the 
suitability of a generic testing method to monitor cleaning effectiveness was 
investigated. The results of this preliminary study revealed discrepancies between 
the results acquired with a generic method compared to the conventional 
microbiological surface examination in the context of surface hygiene monitoring. 
The results demonstrate the higher efficiency of the semi-automatic system in 
comparison to the mechanical system on surfaces with the same characteristics. 
The results also indicate that in both of applied the semi-automatic systems, 
cleaning effectiveness depends on the surface accessibility and cleaning 
direction. Based on the results presented, we can conclude that for maximum 
benefit, visual, non-microbiological, and microbiological methods should be 
combined as an integrated cleaning monitoring strategy.
key words: cleaning, two-bucket system, box system, mechanical cleaning, 
visual inspection, microbiological control, hygiene
Received: 12. 12. 2017 
Accepted: 18. 12. 2017
Original scientific article 
© Inštitut za sanitarno inženirstvo, 201756

inTRODUcTiOn 
The environment of the processes with high hygiene control to prevent 
product contamination is an important factor in determining the quali-
ty and safety of the final products. Sandle [1] noted that cleaning and 
disinfection are necessary in order to prevent microorganisms surviv-
ing in cleanrooms and for maintaining a level of hygiene in laborato-
ries. Cleaning is needed to remove soil (such as protein and grease) 
from surfaces, and disinfection, if necessary, to inactivate or to kill 
microorganisms. As Moore and Griffith [2] stated, ‘cleanliness’ is, 
however, a relative concept: what is acceptable as being ‘clean’ in one 
situation may be unacceptable in another. Lelièvre et al. [3] asserted 
that cleaning is a complex phenomenon whose efficiency depends on 
production conditions and the design of equipment, and on operating 
conditions. Indeed, soils generated during production are often com-
plex, containing microorganisms as well as organic material, which 
could modify both the microorganisms and the solid surface proper-
ties [3]. Prabu et al. [4] pointed out that pharmaceutical products and 
active pharmaceutical ingredients (APIs) can be contaminated by oth-
er pharmaceutical products or APIs by cleaning agents, by microor-
ganisms, or by other materials (e.g., airborne particles, dust, lubri-
cants, raw materials, intermediates, and auxiliaries). Adequate 
cleaning procedures are essential in order to avoid product contamina-
tion especially microbiological contamination. Documented standard 
cleaning procedures for each piece of equipment should be prepared 
for a comprehensive infection prevention strategy and an important 
step in the manufacture of pharmaceutical products [5, 6]. It is vital 
that the equipment design is evaluated in detail in conjunction with 
the product residues that are to be removed, the available cleaning 
agents and cleaning techniques when determining the optimum clean-
ing procedure for the equipment. Cleaning procedures should be suffi-
ciently detailed to remove the possibility of any inconsistencies during 
the cleaning process. The following parameters are to be considered 
during cleaning procedures [5]. Shi and Zhu (2009) indicated that bi-
ofilms were often established by various microorganisms on the equip-
ment surfaces of the production line. L. monocytogenes became one of 
the major causes of contamination of food products or transmission of 
diseases. Therefore, it is very important to develop cleaning and disin-
fection methods and control systems in food-processing plants and en-
vironments. Prabu et al. [4] indicated that cleaning has recently at-
tained a position of increasing importance in the pharmaceutical indus-
try. Virtually every aspect of manufacturing involves cleaning, from the 
initial stages of bulk production to the final dosage form to ensure the 
safety, identity, strength, quality, or purity of the drug product. Modern 
pharmaceutical manufacturing involves highly technically trained per-
sonnel, complex equipment, sophisticated facilities, and complex proc-
esses. Akl et al. [7] indicated that the cleaning procedures for the 
equipment must be validated according to good manufacturing practice 
(GMP) rules and guidelines. Cleaning validation is, however, a signifi-
cant analytical challenge for the pharmaceutical industry [8]. The pur-
M. Jevšnik, A. Ovca, P. Raspor A comparison of three different cleaning methods for reducing contaminants on contact surfaces...
Cleaning and disinfection are 
necessary in order to prevent 
microorganisms surviving in 
cleanrooms and for 
maintaining a level of hygiene 
in laboratories.
International Journal of Sanitary Engineering Research Vol. 11  No. 1/2017 57
 
pose of cleaning validation is to prevent contamination and cross-con-
tamination in pharmaceutical dosage forms [4]. Cleaning validation is a 
documented process that proves the effectiveness and consistency of 
cleaning pharmaceutical production equipment. Cleaning validation 
consists of two separate activities: the first is the development and vali-
dation of the cleaning procedure used to remove drug residues from 
manufacturing surfaces and the second involves the development and 
validation of methods for quantifying residuals from the surfaces of 
manufacturing equipment. Furthermore, many sampling points of the 
manufacturing facility and the manufacturing equipment have to be 
tested to verify the occurrence of contamination [7]. Peles et al. [9] 
stated that the typical residual acceptance limits (RAL) used to verify 
the cleanliness of pharmaceutical manufacturing equipment are select-
ed for residuals that are deemed to be a risk to subsequent products 
based on potency and toxicity. The limits are defined as residual mass/
surface area (μg/cm2) and fall well below the accepted “visibly clean” 
limit of 100 μg per 25 cm2 [10, 11]. The residual mass on the manu-
facturing equipment surface is quantified with a validated analytical 
methodology from swab extracts or rinse, the products of swab or rinse 
sampling [9].
Griffith et al. [12] demonstrated that the effectiveness of sanitation pro-
cedures has traditionally been evaluated using different methods, such 
as visual inspection, swabs, dipslides and contact plates. Visual inspec-
tion is insufficient for defining cleanliness [13] or for objectively evaluat-
ing the microbial contamination of all surfaces [14], although this meth-
od is still widely used to assess the level of cleanliness [15]. ATP 
bioluminescence is a widely used technique for the rapid validation 
about cleaning effectiveness. Compared with traditional microbiological 
testing, ATP bioluminescence has advantages including the rapidity of 
its results, which can be obtained within 2 min [15].
Among the rapid tests, Oberyszyn and Robertson [15] developed a 
method to examine aerosol containment using a modified, commer-
cially available product called Glo Germ® (Glo Germ, Moab, UT). This 
product is used for teaching aseptic techniques in hospitals, industry, 
restaurants, and schools and is visualized with ultraviolet (UV) or 
black light. Glo Germ® is available in three forms: a white powder, an 
orange oil-based suspension, and a white lotion based suspension of a 
melamine copolymer resin. Carrascosa et al. [16] summarised the re-
sults of some studies, which considered rapid techniques to be par-
ticularly useful in large manufacturing plants where regular and fre-
quent monitoring can provide management with data on trends. In the 
case of ATP, it also provides rapid results of the amount of organic re-
mains and microbial contamination on the surfaces of establishments. 
Calvert et al. [17] pointed out that this method does not identify the 
quantity of the microorganisms or contaminant species; it can be used 
as a medium for monitoring hygiene and verifying cleanliness. Conse-
quently, to monitor the efficacy of disinfection procedures, some 
microbiological testing (using dip slides, contact plates, or swabs) may 
be required [16].
 M. Jevšnik, A. Ovca, P. RasporA comparison of three different cleaning methods for reducing contaminants on contact surfaces...
Compared with traditional 
microbiological testing, ATP 
bioluminescence has 
advantages including the 
rapidity of its results, which 
can be obtained within 2 min.
© Inštitut za sanitarno inženirstvo, 201758

The aim of this study is to analyse three different cleaning procedures, 
applying their specific protocols (the double bucket system, the box sys-
tem, and the mechanical cleaning) in order to determine the differences 
between them and to examine their hygienically suitability when used in 
processes of high hygiene control. To perform this study holistically, we 
also included cleaning verification with a generic test.
MATeRiALs AnD MeTHODs 
surface cleaning techniques
The three different cleaning techniques described in Table 1 were evalu-
ated. 
Table 1: Description of cleaning techniques
cleaning type cleaning procedure 
Box system
The box system provides prepared cleaning wipes impregnated with 1% cleaning solution* ready to 
use and stored in a box fixed on the handcart. The excess cleaning solution is strained off and stored 
in the separate compartment under the box. Wipes are used via the telescoping stick and changed 
after approximately every 2 m2 or more often if cleaning effectiveness is not sufficient. There is no 
wring-out step. Used wipes are collected in a separate compartment also fixed on the handcart. 
Double bucket 
system
Two buckets fixed in the handcart are filled with 1% cleaning solution*. The first (blue) bucket contains 
15L and the second (red) bucket contains 2L of prepared cleaning solutions. A cleaning wipes wringer is 
located above the red bucket. The wipe is first soaked in the red bucket, wring out and used for 
cleaning. After that, approximately every 2m2 the wipe is soaked again into the red bucket, rinsed and 
wrung out, followed by soaking it in the blue bucket and wringing it out. After the cleaning procedure in 
one room is finished, the cleaning solution in both buckets is replaced with a new one. 
Mechanical 
cleaning
The cleaning machine is composed of a reservoir for clean water (filled in before the cleaning 
procedure) and the dosage compartment containing a 1% cleaning solution*. The cleaning procedure 
is executed with the round horizontal wheel in the bottom of the cleaning machine. After the cleaning 
procedure is finished, the wastewater is removed from the reservoir, followed by rinsing and drying 
the equipment. Also, the cleaning wheel coming into contact with the surface is rinsed under running 
water and dried. 
Legend: *Alcohol-based cleaner suitable for use on all water-resistant surfaces, objects, and floor coverings as well as on coated floors. 
Ingredients according to 648/2004/EC [18] Non-ionic surfactants < 5%, water-soluble solvents, fragrances (linalool), preservatives 
(methyl-/methylchloroisothiazolinone). pH value (concentrate): approx. 7 pH value (ready-to-use solution): approx. 7.5
The box and double bucket system were evaluated in two separate but 
comparable areas. Mechanical cleaning was evaluated in the area typi-
cal for that type cleaning. The surface material evaluated was the same 
in all three areas. 
sampling points 
Sampling points (20 cm2 each) were systematically selected regardless of 
the area and cleaning type investigated (Table 2). When selecting the 
sampling points, accessibility and workload in the area as criteria were 
considered. Sampling points 1 to 6 were equally distant from each other 
(50 cm) and, in the case of sampling points 1 to 4, equally distant from 
the walls and corners (15 cm). To assure that a sampling point was al-
ways on the same spot, the centre of the sampling point was marked 
with a small black dot resistant to the cleaning procedures evaluated. 
M. Jevšnik, A. Ovca, P. Raspor A comparison of three different cleaning methods for reducing contaminants on contact surfaces...
International Journal of Sanitary Engineering Research Vol. 11  No. 1/2017 59
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surface visual control with Glo Germ®
On each sampling point from 1 to 6 (Table 2), different kits (lotion-
based, oil-based, and powder) were deposited before the cleaning pro-
cedure. Each kit was first deposited on the sampling point in the size of 
a pea and then distributed with a cotton swab on a surface of 20 cm2. 
There was no cleaning of the surface for at least 20 minutes after depo-
sition. After the cleaning procedure had been completed, each sampling 
point was checked in detail under the UV light. If there were no kit re-
sidual left on the surface, the sampling point was evaluated with a mark 
of 1 during evaluation. If there were any remains left on the surface the 
sampling point was evaluated with a mark of 0.
surface sampling and microbiological analysis 
Systematic unannounced surface sampling was executed in three se-
quences in the case of each type of cleaning. During each sequence, 
two sampling intervals were done. Before the first surface sample (BC) 
was taken, the surface cleaning was not done for at least 24 h. The 
second sample (AC) was taken 25 minutes after the cleaning procedure 
to assure that the sampling point was completely dry. To exclude clean-
ing accessories as a possible cause of contamination cleaning solutions 
and wipes were also sampled before the cleaning procedure and ana-
lysed in each sampling sequence.
Surface samples and samples from cleaning wipes (Box and double 
bucket system) were taken with sterile swabs (cotton swab in 9 mL 
sterile physiological solution). The surface sampling technique was ap-
plied according to the ISO18593 standard [19]. The cleaning solution 
was collected in sterile 100 mL containers prior to the cleaning proce-
dure starting. 
Microbiological analysis was performed in an internal microbiological 
laboratory of a company with processes of high hygiene control. Ac-
cording to the internal company standards of environmental microbio-
logical quality, Gram+ bacteria were determined. Surface samples were 
incubated on Soybean Casein Digest Agar Medium for 5 days at 30 ± 
2 °C. Before incubation on agar media, samples of cleaning solutions 
were treated with aseptic membrane filtration (0,46 μ) in a laminar flow 
cabin. Because internally determined warning and action limits for 
Gram+ bacteria were not exceeded in AC samples, no further specific 
Table 2: Description of sampling points
sampling point sampling point criteria 
1 Right corner area close to the room entrance.
2 Right corner area opposite to the room entrance. 
3 Left corner area opposite the room entrance.
4 Left corner area close to the room entrance.
5 Area in the middle of the room opposite to the room entrance.
6 Area in the middle of the room close to the room entrance.
 M. Jevšnik, A. Ovca, P. RasporA comparison of three different cleaning methods for reducing contaminants on contact surfaces...
Surface samples and samples 
from cleaning wipes were 
taken with sterile swabs.
Microbiological analysis was 
performed in an internal 
microbiological laboratory of 
a company with processes of 
high hygiene control.
© Inštitut za sanitarno inženirstvo, 201760
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analysis were done. Standards of environmental microbiological quality 
(warning limit and action limit) are internal in their nature and therefore 
not published in this paper. 
ResULTs 
Simple visual inspection of the sampling points after cleaning was in all 
cases evaluated as visually clean because there were no kit residues on 
the surfaces that would be visible to the naked eye. However, based on 
the results presented in Table 3, we can determine that based on the 
GloGerm® method there are differences visible under UV light. The re-
sults in Table 3 demonstrate that the most effective way of cleaning is 
mechanical cleaning, which successfully removed all three kit types 
from the surface in all sampling points except 1st and 6th. Monitoring of 
cleaning effectiveness after applying the system and the two-bucket 
system has revealed that the test kit applied on the surface was often 
smudged (especially when sampling points are more difficult to reach) 
and, therefore, evaluated as not being sufficiently clean. Comparison of 
the box system and the two-bucket system also reveals that the oil-
based kit is more successfully removed from the surface with the box 
system, while efficiency in case of other two kits applied is comparable 
and related more to the sampling point. We can see that situation at 
sampling point 1 and 6 is generally, at least, satisfying (Table 3). 
Table 3: Evaluation of surface cleanliness after cleaning according to cleaning type and the sampling point using Glo Germ® 
method
cleaning type kit type
sampling point
1 2 3 4 5 6
Box system
Lotion-based 0 1 1 0 1 0
Oil-based 1 1 1 1 1 1
Powder 0 1 0 0 1 0
Double bucket system
Lotion-based 0 1 1 1 1 0
Oil-based 0 1 0 0 0 0
Powder 1 0 1 1 0 0
Mechanical cleaning
Lotion-based 0 1 1 1 1 0
Oil-based 0 1 1 1 1 0
Powder 0 1 1 1 1 1
Legend: 1 – Complete absence of the kit under UV light; 0 – remains of the kit visible under UV light
A microbiological investigation was also conducted. In most of the cas-
es presented in Table 4, the number of CFU is already low before clean-
ing. The internally defined surface hygiene standard defined as action 
limit of 200 CFU is not crossed, indicating good hygiene practice about 
the surfaces investigated. After cleaning, the degree of purity signifi-
cantly improves in all cases, demonstrated as lower microbiological 
counts. Only in one case of mechanical cleaning is the internally defined 
surface hygiene standard, with the minimal limit of 50 CFU, not 
reached after the cleaning (Table 4). 
M. Jevšnik, A. Ovca, P. Raspor A comparison of three different cleaning methods for reducing contaminants on contact surfaces...
International Journal of Sanitary Engineering Research Vol. 11  No. 1/2017 61
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The microbiological investigation of cleaning solutions was on average 
between 8 and 11 CFU/mL, which is lower than the internally defined 
action limit (100 CFU/mL). The microbiological investigation of swabs 
taken from cleaning wipes yielded no microbiological counts (CFU). 
Calculating the results from Table 4 into an average cleaning effective-
ness according to the cleaning type, we can observe the higher effi-
ciency of box system and two-bucket system at all sampling points 
when compared to the mechanical cleaning (Figure 1), which is contra-
ry to the results obtained with the GloGerm® method. However, we 
have to consider that the microbiological counts before cleaning were 
higher in the case of mechanical cleaning (Table 4). This could be relat-
ed to the greater frequency of workload in comparison to the other two 
areas evaluated. Another reason for the lower efficiency of mechanical 
cleaning could be related to the fact that after the mechanical cleaning 
procedure is accomplished more water is still present on the surface in 
comparison to the box system and two-bucket system. 
Closer examination of the cleaning performance according to the sam-
pling point indicates that effectiveness is also related to the accessibility 
of the cleaning area during the cleaning procedure. Sampling point 6, 
located in the middle of the room, has the lowest discrepancy in the 
cleaning efficiency when all three cleaning methods are compared (Fig-
ure 1). In addition, the cleaning efficiency in the case of sampling point 
1 (not considering the cleaning type) is generally better compared to 
Table 4: Microbiological situation (CFU/mL) before and after cleaning at the surface after microbiological examination of 
surface sampling in three sequences of (two samples in one sequence) according to the cleaning type and the sampling 
point
cleaning type
sampling 
sequence
sampling 
interval
cFU/mL at each sampling point 
1 2 3 4 5 6
Box system
1st 
BC 41 4 13 15 22 97
AC 0 0 0 3 0 2
2nd 
BC 13 4 11 13 2 8
AC 0 2 0 0 0 0
3rd 
BC 16 6 2 3 3 10
AC 0 2 0 0 0 1
Double bucket 
system
1st 
BC 9 12 18 9 1 2
AC 2 0 0 0 0 0
2nd 
BC 6 3 5 72 15 5
AC 0 0 0 2 0 0
3rd 
BC 21 30 7 3 19 4
AC 0 1 2 1 0 0
Mechanical 
cleaning
1st 
BC 53 67 91 107 59 44
AC 7 23 1 3 2 0
2nd 
BC 45 47 68 58 23 6
AC 6 46 7 39 13 1
3rd 
BC 93 31 120 55 31 29
AC 3 1 69 21 10 2
Legend: BC – Before cleaning; AC – After cleaning
 M. Jevšnik, A. Ovca, P. RasporA comparison of three different cleaning methods for reducing contaminants on contact surfaces...
© Inštitut za sanitarno inženirstvo, 201762
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sampling points 2–4 in spite of their locations, which are quite similar. 
This also indicates that the cleaning direction is important. The area of 
sampling point 1 was cleaned first in the case of all three cleaning 
types, which is again contrary to the results gained with GloGerm® 
method (Table 3) where sampling point 1 was (other than sampling 
point 6) evaluated as at the least effectively cleaned.
DiscUssiOn
The scarcity of advanced and recent publications in the area of general 
hygiene management is obvious in scientific literature. If the publica-
tions exist, they are focused on particular types of interests, which are 
frequently about pathogens. Consequently, we lack data that would en-
able a comparison of the state of the art in general, and we cannot de-
termine the microbial population dynamic in this area of activity. The 
main focus of each cleaning procedure is to ensure the required levels 
of cleanliness of different places, the workspace, equipment and other 
accessories, which all influence the safety, quality, and effectiveness of 
the final products. This is not only the elimination of particular patho-
genic species. Cleaning does not entail the end of a productive proce-
dure but the beginning of the procedure of a new product. Therefore, if 
cleaning is not also taking into account general hygiene, it easily brings 
the system into a situation in which certain spoilage microflora or even 
potentially pathogenic flora are accumulating resistance and slowly be-
gin to predominate. Therefore, it is of crucial importance to screen this 
aspect of cleaning efficiency as well. For that reason, we performed this 
study. 
Al-Hamad and Maxwell [20] determined that the risk of acquiring infec-
tion from environmental surfaces, such as floors, walls, or the surfaces 
Figure 1:  
Average cleaning effectiveness (%) 
according to the cleaning type 
expressed as a reduction in the 
number of CFU/mL after cleaning;  
n – number of sampling sequences 
M. Jevšnik, A. Ovca, P. Raspor A comparison of three different cleaning methods for reducing contaminants on contact surfaces...
International Journal of Sanitary Engineering Research Vol. 11  No. 1/2017 63
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of medical equipment or furniture, is probably small. However, there is 
a large body of clinical evidence, derived from case reports and out-
break investigations, which does identify links between poor environ-
mental hygiene and the transmission of micro-organisms causing hospi-
tal-acquired infection. Srey et al. [21] emphasized that pathogenic 
microorganisms in biofilms formed in different food industries settings 
are a source of food contamination. As the demand for fresh, ready-to-
eat and processed foods increases, many studies are needed to address 
biofilm removal and disinfectant efficacy in food industries. Sinsheimer 
et al. [22] showed that professional wet cleaning has been determined 
as an energy efficient, nontoxic, zero-emission technology, and it can 
be used to process previously dry cleaned garments. In our study, the 
monitoring of cleaning effectiveness after applying the box system and 
the two-bucket system has revealed that test kits applied on the sur-
face were often smudged and therefore evaluated as not being suffi-
ciently clean. This demonstrates that the cleaning effect is largely de-
pendent on the cleaning type applied and cleaning technique applied by 
the cleaning staff. Sinsheimer et al. [22] also concluded that the clean-
ers they studied in California who switched to professional wet cleaning 
were able to maintain their level of service and customer base while 
lowering operating costs. They also found that the cleaners were able to 
transition to professional wet cleaning without a great degree of difficul-
ty and were highly satisfied with the new technology [22, 23].
In this preliminary study, according to the GloGerm® method the re-
sults indicate that the most effective way of cleaning is mechanical 
cleaning (Table 3), which is not the case when the microbiological eval-
uation is done (Table 4) revealing the discrepancy between the results 
gained with the generic method compared to conventional microbiologi-
cal examination. The results of average cleaning effectiveness according 
to the cleaning type demonstrated the box system to be the most effi-
cient followed by the two-bucket system and the mechanical method 
(Figure 1). In the case of mechanical cleaning, it should be noted that 
workload was higher compared to other two areas when this cleaning 
method was used as intended (Table 4). Another reason for the lower 
efficiency of mechanical cleaning could be related to the fact that, in 
comparison to the box and two-bucket systems, after the cleaning pro-
cedure is accomplished more water remains present on the surface. Al-
though both methods applied for surface hygiene monitoring cannot be 
directly compared, the contrast between the results of the GloGerm® 
method and microbiological analysis indicates the need for the valida-
tion of generic methods before being applied as a standard way of mon-
itoring of surface cleanliness. The absence of a test kit does not neces-
sarily also mean a better microbiological situation and vice versa. 
Moreover, one can observe that the tests applied might be linked to the 
cleaning process (Table 3). It seems that mechanical cleaning can be 
handled well with all three test kits, which was not the case with the 
other two cleaning protocols. Closer examination in other industrial cir-
cumstances would also be beneficial to clarify this inconsistency in test 
reliability. The results of our preliminary study support the conclusions 
of Griffith et al. [24], who demonstrated that for maximum benefit, vis-
 M. Jevšnik, A. Ovca, P. RasporA comparison of three different cleaning methods for reducing contaminants on contact surfaces...
Cleaning effect is largely 
dependent on the cleaning 
type applied and cleaning 
technique applied by the 
cleaning staff.
© Inštitut za sanitarno inženirstvo, 201764

ual, non-microbiological and microbiological methods should be com-
bined, resulting in the production of an integrated cleaning monitoring 
strategy. Moore and Griffith [2] indicated that conventional microbio-
logical techniques would detect only the microbial component of any 
residual surface contamination. Furthermore, despite the use of hygiene 
swabs enabling the detection of relatively low levels of bacteria on a wet 
surface, previous studies have indicated that the recovery of microor-
ganisms is severely compromised when the sampled surface is dry. 
It was ascertained that the accessibility of sampling points is correlated 
with the effectiveness of the cleaning procedure. An important step in 
the manufacture of pharmaceutical products, demonstrated by Akl et 
al. [7], is the cleaning of equipment and surfaces. The cleaning proce-
dures for the equipment must be validated according to GMP rules and 
guidelines. The main objective of cleaning validation is to avoid con-
tamination between different productions or cross-contamination [7]. 
Resto et al. [25] indicated the main requirements for the validation of 
cleaning processes in the pharmaceutical industry, specifying that no 
detergent should remain after the cleaning process, what is similar for 
processes for high hygiene control. The accessibility of sampling points 
during the cleaning procedure and cleaning direction defined the effec-
tiveness of cleaning performance (Table 4, Figure 1) according to the 
sampling point (e.g. sampling points 5 and 6 located in the middle of 
the room in case of the double bucket system have higher cleaning effi-
ciency in comparison to other sampling points). We estimated good hy-
giene practise considering the surfaces investigated before cleaning 
(e.g. in most cases the number of CFU is low under the internally de-
fined action limit (200 CFU)) and after cleaning (e.g. the degree of pu-
rity in all cases except one improves, demonstrated as lower microbio-
logical counts) (Table 4). For validation of the cleaning process and for 
continuously educating cleaning staff, quick and objective feedback on 
the surface cleanliness is of paramount importance [26].
Luick et al. [27] found that subjective and objective measures of cleanli-
ness based on visual inspection, ATP assay, or aerobic culture were all 
able to demonstrate significant increases in the proportion of surfaces 
considered clean if analysed before and after the routine terminal clean-
ing protocol described in this paper. However, if visual inspection were 
used alone, a significantly higher proportion of surfaces would be con-
sidered clean before terminal cleaning.
cOncLUsiOn 
The evaluation of three different cleaning procedures revealed that 
cleaning effectiveness depends on the surface accessibility and cleaning 
direction. Discrepancies between results acquired with a generic meth-
od compared to conventional microbiological surface examination in the 
context of surface hygiene monitoring were discovered. The semi-auto-
matic system has shown higher efficiency in comparison to the me-
chanical system on surfaces with the same characteristics. We can 
conclude that an integrated cleaning monitoring strategy should be 
M. Jevšnik, A. Ovca, P. Raspor A comparison of three different cleaning methods for reducing contaminants on contact surfaces...
It was ascertained that the 
accessibility of sampling 
points is correlated with the 
effectiveness of the cleaning 
procedure.
The evaluation of three 
different cleaning procedures 
revealed that cleaning 
effectiveness depends on the 
surface accessibility and 
cleaning direction.
International Journal of Sanitary Engineering Research Vol. 11  No. 1/2017 65
 
based on a combination of visual, non-microbiological and microbiologi-
cal methods for optimal cleaning results.
This preliminary study provides vital information in the context of the 
very small number of publications in the field of general basic hygiene 
management. Assessing all interactions within cleaning procedures in 
different hygiene processes, it seems that many issues do not have the 
attention they deserve. However these kinds of research are internal in 
its nature and have often a confidential status. Despite of lack of pub-
lished studies in this field, this kind of research is constantly underway 
in processes of high hygiene control including the one participating in 
current study, as this is one way of ensuring adequate product quality. 
This is of particular importance, as results of our preliminary study 
might serve as a basis for further professional and scientific research. 
This preliminary study’s findings suggest that future research should ex-
plore these themes in greater depth.
LiMiTATiOns OF THe sTUDY
The reader of this paper should take into consideration a few limitations 
of the current study, which is of a preliminary nature. The study was 
conducted in a single institution for the processes of high hygiene con-
trol with a modest sample size and minimal sampling sequences. There 
was no intention to validate a generic method for surface hygiene evalu-
ation. Smaller surfaces were evaluated under semi-controlled circum-
centres with regards to the cleaning solution, surface characteristics 
and location of sampling points. The possible effect of the cleaning staff 
was not considered.
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 M. Jevšnik, A. Ovca, P. RasporA comparison of three different cleaning methods for reducing contaminants on contact surfaces...
Assessing all interactions 
within cleaning procedures in 
different hygiene processes, 
it seems that many issues do 
not have the attention they 
deserve.
© Inštitut za sanitarno inženirstvo, 201766
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M. Jevšnik, A. Ovca, P. Raspor A comparison of three different cleaning methods for reducing contaminants on contact surfaces...