2. principal factor contributing to the buildup and spread of
airborne microbial contamination in many healthcare
facilities (Ekhaise et al., 2008).
Individuals or clients with pre-existing health problems
and have depressed immune system and are going
through treatment are very susceptible to indoor air
exposure. Hence, both indoor and outdoor air pollutions
are some of the most severe challenges of our time.
Several airborne diseases have been related to the indoor
air quality. Indoor air quality is a significant issue in health
care especially in the developing countries. Consequently,
the presence of airborne microorganism that may cause
nosocomial infections in Health care facilities should be
regarded as a major concern when providing particular
care to patients and hospitals (Ekhaise et al., 2008).
So far in many countries in the Sub-Saharan African
region including Malawi, there are no guidelines for
microbiological quality of indoor air. Furthermore, there
isn’t any SADC directive addressing this; therefore it is
assumed to be based on particular countries.
Therefore, the purpose of this study was to determine the
extent of indoor air microbial contamination in maternity,
surgical and medical wards of Daeyang Luke Hospital
(DLH) as an important factor in nosocomial infection chain.
The findings of this study are very helpful to evaluate the
adequacy of environmental control procedure of ward
environments at Daeyang Luke Hospital.
MATERIAL AND METHOD
This study was carried out between the months of March to
July 2015 in the Daeyang Luke Hospital, Lilongwe Malawi.
Daeyang Luke Hospital has a bed capacity of 200 and
provides services for approximately 70,000 inpatient and
outpatient attendances a year coming from a catchment
population of about two million people. Maternity, Female
Surgical, Male Surgical, Female Medical, Male Medical,
Emergency and Pediatric wards were used for sample
collection.
Bacteria and fungi measurements were made by passive
air sampling technique; the settle plate method using 9 cm
diameter petri dishes (63.585 cm
2
areas) (Pasquarella et
al., 2000). The sampling height which approximated human
breathing zone of 1 metre above the floor and at the centre
of the room was used. Bacteria and fungi were collected on
2% nutrient agar and 4% sabouroad agar respectively. To
avoid self contamination of agar plate during air sampling,
sterile gloves, mouth masks and protective gown were
worn, and before it was used the agar plate was checked
visually for any microbial growth. To obtain the appropriate
surface density for counting and to determine the load with
respect to time of exposure, the sampling times were set at
30, 60, 90 minutes. Moreover, samples were collected
twice a day at 8:30 am and 4:00 pm by taking into
consideration the variation of density of occupant and
environmental factors.
After exposure, the sample were taken to Daeyang
University Laboratory and incubated at 37°C for 24 hours
for bacteria and at 25°C for 3 days for fungi.
The colony forming units (CFU) were enumerated and
colony forming units per cubic meter (CFU/m
3
) were
determined, taking into account the following equation as
described by Omeliansky (Borrego et al., 2010):
N = 5a x 10
4
(bt)
-1
Where:
N: microbial CFU/m
3
of indoor air
a: number of colonies per petri dish
b: dish surface, cm
2
t: exposure time, minutes
IBM SPSS Statistics version 20.0 software was applied to
determine the likelihood of statistical difference between
the concentrations of bacteria and fungi measured at
different sampling places and the linearity was determined
between the concentrations of bacteria and fungi
measured.
RESULTS
A total of 84 samples were used to determine the indoor air
microbial loads of seven wards of Daeyang Luke Hospital.
The results were expressed as concentration,
concentration range, arithmetic mean and standard
deviations of bacteria and fungi aerosol present in the
investigated wards as presented in Tables 1, 2 and 3. The
microbial air quality standards of the investigated wards
have been presented in Table 4.
It can be observed from the results that the highest
bacterial colony forming unit per m
3
(CFU/m
3
) of 3495 was
recorded at 4:00 pm in emergency ward at 90 minutes
while the lowest bacterial CFU/m
3
of 366 was recorded at
8:30 am in pediatric ward at 30 minutes as in Table 1 and
Figure 1.
And the highest fungi CFU/m
3
of 3993 was recorded at
8:30 am in female surgical ward at 90 minutes while the
lowest CFU/m
3
of 786 was recorded at 4:00 pm in
maternity ward at 30 minutes as in Table 2 and Figure 1.
The concentration of bacteria and fungi aerosol in the
indoor environment of Daeyang Luke Hospital wards
during the period of study, estimated with the use of settle
plate method, ranged between 366 – 3993 CFU/m
3
as in
Table 3. It can also be observed in Figure 1 that bacterial
and fungal air contamination was generally lower in the
morning than in the afternoon in all the investigated wards
during the period of study.
The results as indicated by the scatter plots in figure 2 of
the bacteria concentration versus fungi concentration show
3. Table 1: Number of bacterial colony counts (CFU) per m3
air at different sampling time of day at different time of exposure
Sampling sites
(Wards)
Sampling time
8:30 am 4:00 pm
Petri dish exposure time (Minutes) Petri dish exposure time (Minutes)
30 (Min) 60 (Min) 90 (Min) 30 (Min) 60 (Min) 90 (Min)
Maternity 602 1271 1442 446 734 1118
Female Surgical 1022 1140 1389 904 1101 1319
Male Surgical 1494 1678 1992 865 878 908
Female Medical 655 983 1048 629 891 979
Male Medical 602 983 891 708 760 1057
Emergency 1599 1861 2813 1756 2045 3495
Pediatric 366 550 778 577 813 1346
Table 2: Number of fungi colony counts (CFU) per m3
air at different sampling time of day at different time of exposure
Sampling sites
(Wards)
Sampling time
8:30 am 4:00 pm
Petri dish exposure time (Minutes) Petri dish exposure time (Minutes)
30 (Min) 60 (Min) 90 (Min) 30 (Min) 60 (Min) 90 (Min)
Maternity 1232 1455 2621 786 1324 1721
Female Surgical 1232 1284 3993 1546 2136 2665
Male Surgical 1599 1765 3512 1074 1599 1651
Female Medical 1101 1848 2506 944 1979 2621
Male Medical 1232 1468 2892 1573 2228 2298
Emergency 1048 2324 2612 1101 1586 2736
Pediatric 891 970 2298 945 1979 1590
Table 3: The range of microbe’s distribution at Daeyang Luke Hospital wards
N Minimum Maximum Mean Std. Deviation
Bacteria CFU/m
3
Fungi CFU/m
3
Valid n
42
42
42
366
786
3495
3993
1178.29
1808.69
668.84
737.10
4. Table 4: An assessment of air quality in the selected wards of Daeyang Luke Hospital according to the sanitary standards for non-industrial premises
Group
of
microb
es
Range
of
values
(CFU/m
3
Pollution
degree
Sampling sites (Wards) and time
Pediatric Emergen
cy
Maternal Female
Surgical
Male
Surgical
Female
Medical
Male
Medical
8:3
0
am
4
p
m
8:3
0
am
4
p
m
8:3
0
am
4
p
m
8:3
0
am
4
p
m
8:3
0
am
4
p
m
8:3
0
am
4
p
m
8:3
0
am
4
pm
Bacteri
a
<50 Very low
50-100 Low
100-500 Intermedia
te
500-
2000
High √ √ √ √ √ √ √ √ √ √ √ √ √
>2000 Very high √
Fungi <25 Very low
25-100 Low
100-500 Intermedia
te
500-
2000
High √ √ √ √ √ √ √ √
>2000 Very high √ √ √ √ √ √
Figure 1: Comparison between fungi and bacteria concentration at Daeyang Luke Hospital wards
5. Figure 2: Correlation between fungi and bacteria concentration at Daeyang Luke Hospital wards
positive linear association (r
2
=0.1847). And this proves that
the indoor air environmental factors of the wards are
favoring the growth and development of bacteria and fungi
population.
The statistical analysis of the results also showed that
the concentration of bacteria that were measured in all
wards were significantly different (p-value=0.01) whereas
the concentration of fungi were not significantly different.
This suggests that most of the microbes were not human
borne (Soto et al., 2009).
The scatter plots of bacteria versus fungi concentration
that have been measured in all sampled wards show
positive linear association with regression coefficient (R
2
=
0.1847, n=42) presented in figure 2.
DISCUSSIONS
In this research, the quantitative interpretation of the
results describing the air quality in the wards of DLH was
evaluated based on the sanitary standards for non-
industrial premises formulated by the European
Commission in 1993. According to this classification, most
of the wards that were included in the study were slightly in
unhygienic condition (Table 4). These might be possibly
because of high density or frequency of patients and
presence of visitors in and out of the wards during this
period of study.
Despite the fact that there is no uniform international
standard on levels and acceptable maximum bioaerosol
loads available in literature (Jyotshna and Helmut 2011).
Different countries have different standards, however,
according to the study conducted by a WHO expert group
on assessment of health risks of biological agents in indoor
environments it was recommended that total microbial load
should not exceed 1000 CFU/m
3
. If higher than this, the
environment is considered as contaminated (Nevalainen
and Morawaska 2009).
In this study, about 31% of the results from the wards
were below the limit of 1000 CFU/m
3
showing that most of
the wards during this period were unhygienic conditions.
Environmental factors such as insufficient ventilation
system might also contribute to the level of microbial load
in the ward as indicated by Wamedo et al. 2012.
According to earlier studies the microbiological quality of
indoor air is formed by two main factors: microbiological
composition of outdoor air and indoor air microbiological
sources (Abdel Hameed and Farag 1999). Outdoor air is
very much influenced by environment, season, the weather
and even daytime. The results of this study shows that
people occupying or visiting enclosed spaces play a
dominating role in the creation of indoor air microbiological
environments. The highest growths of microorganisms are
observed in wards that are frequently visited by patients’
visitors and the emergency ward. However, the presence
of good ventilation system inside buildings such as
6. hospitals element the influence of indoor source in causing
nosocomial infections.
Additionally, it is necessary to adopt the guidelines for
the design and construction of new health-care facilities
and for renovation of existing facilities in order to control
indoor air-quality.
CONCLUSION
In conclusion, the pediatric and medical wards were the
least contaminated wards during the period of study while
the rest of the investigated wards were highly
contaminated with bacteria and fungi, hence they might be
potential risk factors for spread of nosocomial infection at
DLH. Thus, immediate intervention is needed to control
those environmental factors which favor the growth and
multiplication of microbes. It is also vital to control visitors
in and out of the wards. Moreover, it is advisable that strict
measures be put in place to check the increasing microbial
load in the hospital environment.
ACKNOWLEDGEMENT
Grateful thanks goes to the management and staff of
Daeyang University and Daeyang Luke Hospital for
providing the facilities for the research work.
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