Advances in Infectious Diseases, 2013, 3, 205-209 Published Online September 2013 ( 205
Bacterial Contamination of Blood and Blood Products at
Mbarara Regional Blood Bank in Rural
South Western Uganda
G. B. Matte Aloysius1,2*, Bazira Joel1, Richard Apecu2, Boum Yap II3, Frederick Byarugaba1
1Department of Microbiology, Faculty of Medicine, Mbarara University of Science and Technology (MUST), Mbarara, Uganda;
2Department of Medical Laboratory Science, Faculty of Medicine, Mbarara University of Science and Technology, Mbarara, Uganda.
3Epicentre Mbarara Research Base, Mbarara, Uganda;
Email: *
Received July 9th, 2013; revised August 7th, 2013; accepted August 16th, 2013
Copyright © 2013 G. B. Matte Aloysius et al. This is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Background: Screening blood donors has practically eliminated viral and bacterial pathogens in blood used for trans-
fusion. However, transfusion-associated bacterial sepsis remains an important health-care concern and the commonest
cause of transfusion-related fatality in resource limited settings. Data on bacterial contamination of blood are scarce
while the demand of blood transfusion is continuously growing. Therefore we conducted a study to determine the
prevalence and typ e of bacterial con tamination in donor blood and bloo d produ cts, at the Mbarara Regio nal Blood Ban k.
Methodology: A total of 510 units of screened blood and blood products consisting of refrigerated whole blood and
packed cells were randomly sampled following aseptic procedures from Mbarara Regional Blood Bank. Two samples
from each unit were collected in universal containers containing Brain Heart Infusion Broth and incubated at 37˚C for
up to 7 days. Subcultures were carried out on Blood agar, Chocolate agar and MacConkey agar. Isolates were identified
by standard microbiologic techniques and drug susceptibility testing was performed by Kirby Bauer disc diffusion
method. Results: Of the 510 samples collected between June and October 2012, 18 (3.5%) samples showed growth.
The contaminants were Staphylococcus aureus 17/18 (94.4%) and Streptococcus viridans 1/18 (5.6%). Isolates were
sensitive to erythomycin, ampicillin, chloramphenicol and ciproflox acin and resistant to penicillin and cloxacillin. Con-
clusion: Blood and blood products from Mbarara Regional Blood have unacceptable levels of bacterial contamination
that can affect patient safety especially in an area with high malaria endemicity. Therefore it is critical to improve hy-
giene precautions in order to minimize bacterial contamination and ensure patient safety.
Keywords: Bacterial Contamination; Blood/Blood Products; Staph ylococci
1. Introduction
Blood transfusion is a medical intervention intended to
provide safe blood or blood components in a cost effec-
tive way to patients who require blood and/or blood
products. However, blood and blood components for
transfusion can be a source of infection to recipients
arising from contamination of these products by a variety
of transmissible agents. Since the 1980’s when the hu-
man immunodeficiency virus (HIV) was recognized,
rigorous screening of blood before it is supplied to re-
cipients was instituted and accepted worldwide [1].
Uganda adopted this rigorous screening of blood in order
to provide safe blood to her population. Blood is
screened for viruses including the Human Immunodefi-
ciency virus (HIV), Hepatitis B virus (HBV), Hepatitis C
(HCV) and for Treponema pallidum, a bacterium. It has
been documented that bacteria can cause morbidity and
mortality from blood and blood transfusion components
In developed countries, transfusion of blood and blood
components has a low but known infectious risk for pa-
tients and remains a threat [4,5]. In the United States,
bacterial contamination is said to account for 15.9% of
all transfusion related fatalities, and is considered the
second commonest cause of death from blood transfusion
after clerical errors [4,6]. Recent data indicate that bacte-
rial contamination has declined by about 50% or more
*Corresponding a uthor.
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Bacterial Contamination of Blood and Blood Products at Mbarara Regional
Blood Bank in Rural South Western Uganda
with contamination being detected in about one in 5000
apheresis platelet concentrates tested [3,7]. The possibil-
ity and problem of bacterial contamination of blood and
blood products have received very little attention on the
African continent [3]. Few countries in Africa have pub-
lished records of bacterial contamination of blood/blood
products. These include Ghana [2,8], Kenya [9] and, Ni-
geria [3]. Many African countries do not have docu-
mented reports on bacterial contamination of blood and
blood products and no record whether these products do
pause a risk of causing morbidity and mortality among
recipients [3]. To the best of our knowledge, in Uganda,
no research has been carried out to determine blood
transfusion-associated infections or whether the blood
and blood components intended for transfusion may be
contaminated with bacteria. Therefore we performed this
study to determine the prevalence of bacterial contami-
nation of blood and blood products supplied by the
Mbarara Regional Blood Bank, identify the types of
contaminating bacteria and determine their antibiotic
susceptibility pattern.
2. Materials and Methods
This was a descriptive cross-sectional study conducted at
the Mbarara Regional blood Bank located in the South
Western Region of Uganda. A total of 510 samples of
blood were collected from blood donors between June
and October 2012 and were selected using non probabil-
ity convenient sampling. Blood and blood products in-
cluded in this study were those that had been screened
and found negative for Human Immunodeficiency virus,
Hepatitis B virus, Hepatitis C virus and Treponema pal-
lidum and had been stored for not more than 35 days.
2.1. Blood and Blood Product Collection from
Blood Bag Units
Blood bags were conveniently sampled. Refrigerated
stored blood in bags was thoroughly mixed, and the tub-
ing was then swabbed with 70% ethanol pads and a ster-
ile syringe was used to withdraw blood from the blood
bag through the line and some of the mixed blood from
the main bag was allowed to seep into the line. About
five milliliters were withdrawn by use of a 5-ml sterile
syringe and 2.5 ml transferred to each of the two Uni-
versal bottles containing the Brain Heart Infusion (BHI)
broth. The end of each line was then sealed to prevent
blood in the line and air from flowing back into the main
bag. Two seals were made, one before the punctured site
to prevent blood from flowing back to the main blood
bag, and the other after the puncture site. The BHI blood
culture bottle cover was then sterilized by flaming b efore
and after inoculation.
The two BHI sample suspensions were incubated at
37˚C and observed daily for any possible signs of bacte-
rial growth (pellicle formation, hemolysis, or turbidity)
for 7 days. Samples found with bacterial growth were
sub cultured using a sterile wire loop-full of each sample
onto blood agar, Chocolate agar and MacConkey agar
plates. Samples were incubated overnight (18 - 24 hours)
at 37˚C. A blind sub culture was performed for samples
which showed no growth on the seventh day. Any bacte-
rial growth was identified using colonial morphology,
Gram stain reaction, and standard biochemical reactions.
2.2. Antibiotic Susceptibility Testing
Antibiotic susceptibility testing was performed by the
Kirby Bauer disc diffusion method [10]. The following
antibiotic discs were used: ampicillin (10 µg), penicillin
(10 µg), chloramphenicol (10 µg), cloxacillin (5 µg),
ciprofloxacin (5 µg), erythromycin (15 µg), and inter-
preted according to the Clinical and Laboratory Stan-
dards Institute [11] guidelines.
2.3. Quality Control
Aseptic techniques were observed at all times during the
collection of the samples. Standard operating procedures
were employed throughout the whole investigative proc-
ess including use of standard Staphylococcus aureus
(ATCC 25923) for Gram-positive organisms. Standard
materials supplied by accredited manufacturers were
used in the study.
3. Results
Of the 510 blood and blood products, 18 units had bacte-
rial growth, indicating a 3.5% prevalence of bacterial
contamination of blood/blood products at the Mbarara
Regional Blood Bank. However, the level of contamina-
tion was higher in packed cell units than in whole blood
(see Table 1).
The majority of isolates 17/18 (94.4%) were Gram
positive, coagulase positive Staphylococcus aureus,
while Gram positive Streptococcus viridans contributed
1/18 (5.6%) of the contamination (see Table 2).
The S. aureus isolates showed a high sensitivity to
ampicillin, chloramphenicol, erythromycin and cipro-
Table 1. Level of contamination according to blood compo-
Type of blood componentGrowth
(n%) No growth
(n%) Total
Whole blood 8 (2.5) 309 (97.5) 317 (100)
Packed cells 10 (5.2) 183 (94.8) 193 (100)
Total 18 (3.5)
492 (96.5) 510 (100)
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Bacterial Contamination of Blood and Blood Products at Mbarara Regional
Blood Bank in Rural South Western Uganda 207
Table 2. Level of contamination according to type of bacte-
Bacteria type Number of blood units contamina te d
Bacteria type Whole blood Packed cells Total
S. aureus 8 9 17 (94.4%)
S. viridans 0 1 1 (5.6%)
Total 8 10 18 (100%)
floxacin. A high resistance of these strains to peniciliin
and cloxacillin was observed (see Figure 1). The S. viri-
dans isolated in one unit of packed cells showed resis-
tance to penicillin and cloxacillin and was sensitive to
chloramphenicol, ampicillin, ciprofloxacin, and erythro-
mycin (data not shown).
Highest resistance to Penicilin and cloxacillin and
lowest resistance to Erythromycin was observed.
4. Discussion
The prevalence of bacterial contamination of blood/blood
products of 3.5% found in this study is lower compared
to other studies carried out in Africa—7% in Kenya, [9],
8.8% in Nigeria, [3] and between 9 to 17.5% in Ghana,
[2,8]. This could be explained by the difference in the
settings across the countries and the time since the im-
plementation of rigorous regulations on blood products.
The prevalence of blood contamination in this study is
however higher than that reported in developed countries.
In the United States, a prevalence of 0.2% was reported
[12], while 0.15% was reported in the UK [13], and 0.1%
was reported in France [14]. The explanation for lower
prevalence in developed countries is attributed to more
rigorous screening procedures practiced in these coun-
Nonetheless it should be noted that despite the lower
prevalence in developed countries, severe annual mor-
bidity and mortality due to bacterial contamination of
blood is considered a cause of significant annual morbid-
ity and mortality [4]. No follow up studies have been
carried out in patients transfused with contaminated
blood to determine the level of morbidity and mortality
in Uganda. Moreover, these data could explain the fever
observed usually 5 days after blood transfusion of chil-
dren treated for severe episodes of malaria in our hospital
(Unpubli shed data).
The organisms isolated in this study were Staphylo-
coccus aureus and Streptococcus viridans. In Ghana, the
isolates reported by a study conducted by Adjei were
Gram-positive bacteria (S. aureus, Coagulase-negative
Staphylococci (CNS), and Bacillus species) and
Gram-negative bacteria (Y. enterocolitica, Citrobacter
freundii, E. coli, P. aeroginosa, and Klebsiella pneumo-
niae) [8]. Opoku-Okrah also in Ghana reported only
Figure 1. Sensitivity patterns of S. aureus to various antibi-
otics (n = 17).
Gram-positive bacteria which included coagulase nega-
tive Staphylococci, Staphylococcus aureus, Corynebac-
teria. The Gram-negative bacteria identified included E.
coli, bactero ides an d Klebsiella pneumonia [2]. A similar
study conducted in Nigeria reported Gram-positive bac-
teria (S. aureus, CNS, Bacillus spp, Listeria spp) to have
been isolated [3]. In Kenya, the isolates included
Gram-negative organisms (Acinetobacter spp., Aeromo-
nas spp., Brevundemonas vescularis, Burkholderia ce-
pacia, Enterobacter sekazaki, Klebsialla pneumonia,
Ochrobacterum anthropi, Oligella urethralis, Pseudo-
monas spp., Rhizob ium radiobacter, Shewanella putrefa-
ciens) and Gram-positive bacteria (Ba cillus spp., Micro-
coccus spp.,and Staphylococcus epidermidis) [9]. In the
BACON, SHOT, and BACTHEM studies carried out in
the United States, UK, and France respectively, Brecher
and Hay, reported the following Gram-positive bacteria
isolated from red cells implicated in transfusion-associ-
ated infections (CNS, Streptococcus spp., Staphylocco-
cus aureus, Enterococcus feacalis, Bacillus cereus,
Propionibacterium acnes,) and Gram-negative bacteria
(Serretia liquifaciens, Serratia marcescens, Yersinia en-
terocolitica, Enterobacter spp., Acinetobacter spp.,
Pseudomonas spp., E. coli, Klebsiella pneumonia, and
Proteus miribalis) [15]. The Staphyloccocus aureus and
Streptoccocus viridans isolated in this study are part of
the skin normal flora and therefore can easily be intro-
duced in the blood if skin disinfection is not performed
properly duri n g bl eeding process.
All isolated organisms in this study showed varying
susceptibility to the tested antibio tics as indicated in Fig-
ure 1. The S. aureus organisms showed resistance to
commonly used antibiotics including penicillin, cloxacil-
lin, chloramphenicol, ampicillin, ciprofloxacin and
erythromycin. The S. viridans isolated showed resistance
to penicillin and cloxacillin and was sensitive to
chloramphenicol, ampicillin, ciprofloxacin and erythro-
mycin. The resistance to cloxacillin and penicillin might
be due to these organisms ability to produce beta lac-
tamases (penicillase) that destroy the B-lactam ring
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Bacterial Contamination of Blood and Blood Products at Mbarara Regional
Blood Bank in Rural South Western Uganda
found in these antibiotics, rendering the antibiotics inef-
fective. In Ghana, it was reported that all Gram-positive
isolates were resistant to cefuroxime, penicillin, ampicil-
lin, and cotrimoxazole but sensitive to cefotoxime, tetra-
cycline, erythromycin, and gentamycin [2,8]. Similarly,
all the Gram-negative organisms isolated were resistant
to cefotoxime (except Y. enterocolitica), tetracycline,
ampicillin, cefuroxime, cotrimoxazole, and chloram-
phenicol but sensitive to amikacin and gentamycin. A
study in Nigeria reported resistance to antibiotics tested
(ampicillin, cotrimoxazile, erythromycin, penicillin, tet-
racycline, rifampicin) except gentamycin, and ceftri-
oxone that ranged from 50% to 100% [3].
One possible explanation for the high resistance of
donor blood isolates may be associated with the ease of
procuring antibiotics over the counter in Uganda, self
medication, and shortfalls in infection control [16]. An-
other possible cause of high resistance could be due to
misuse of antibiotics by cattle farmers, Amanya, (unpub-
lished) reported bacterial resistance to antibiotics on
bacteria isolated from milk which included S. aureus,
Klebsiella pneumonia, S. agalactiae, and E. coli which
showed resistance to the commonly used antibiotics in-
cluding tetracycline, gentamycin and penicillin. This can
imply that people consuming milk and milk products
may acquire bacterial strains from milk and milk prod-
ucts that are already resistant to the commonly used anti-
5. Conclusion
Bacterial contamination of blood was found to be 3.5%.
Staphylococcus aureus was found to be the major con-
taminant with 17 out of 18 organisms isolated (94.4%)
while Streptococcus viridans contributed 1/18 (5.6%).
The isolates are known to be part of the skin normal flora.
The organisms showed increased resistance to penicillin
and cloxacillin but susceptible to ampicillin, chloram-
phenicol, erythromycin and ciprofloxacin.
6. Recommendation
While the Mbarara Regional Blood Bank is doing a
commendable job in provision of safe blood and blood
products emphasis should be put on ensuring proper dis-
infectio n o f phlebotomy site s .
Policy makers should ensure emphasis of blood safety
during phlebotomy by providing quality disinfectants.
Routine antibiotic susceptibility testing is recommended
in all cases of post-transfusion sepsis.
7. Acknowledgements
We appreciate the financial, material and moral support
offered to us by Mbarara University of Science and
Technology, Department of Microbiology and; Epicen-
tre Mbarara Research Base. Special thanks to Dr. At-
wine Daniel of Epicentre for the support towards the data
analysis of our study .
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