Nigerian Journal of Paediatrics 2011;38 (3):136 - 141
ORIGINAL
Onalo R
Rate of isolation of streptococcus species
Adeleke SI
Nwalorzie C
from children with bacterial infections:
Njoku R
an indication for introduction of
streptococcal vaccines
Received:18th May 2011
Abstract Background:
Version 3.5.1. Statistical
Accepted: 19th July 2011
Streptococcus species are among
significance was set at p < 0.05.
the commonest bacterial causes
Results: A total of 2,247 samples
Onalo R ( ) Adeleke SI,
of childhood morbidity in
were received during the study
Nwalorzie C
developing countries.
period. Of the 1,242 bacteria
Department of Paediatrics,
Streptococcal diseases in children
isolated, 502 (40.4%) were
University of Abuja Teaching
have not been as well
Staphylococcus
aureus , 232
Hospital, Gwagwalada,Abuja
characterized in Nigeria as it has
(18.7%) were Escherichia coli and
E-ma il: richardonalo@yahoo.com
been in industrialized countries.
146 (11.8%) were Streptococcus
The rudimentary nature of public
Tel: +2348037017678:
species: 78 were isolated from
health surveillance makes the true
blood, 9 from sputum, 11 from
epidemiology of the disease
Njoku R
throat swabs and 28 from other sites
difficult to ascertain. The
while urine and eye swabs had 10
Department of Medical
predominance of Streptococcus
each. One hundred and six (72.6%)
Microbiology, University of
pneumoniae in the causation of
of the streptococci were from
Abuja Teaching Hospital,
invasive diseases has led to the
children aged 5 years and below.
advocacy of inclusion of
Gwagwalada, Abuja Nigeria
Most of the Streptococci (88.1%)
pneumococcal vaccine in the
were untyped. Among the 17
National Programme on
Streptococcal isolates typed, 10
Immunization. However, local
were Streptococcus
pneumoniae
data critical to inform on vaccine
a n d
t h r e e
w e r e
g r o u p
B
deployment are scarce, thus the
Streptococcus.
need for the present study.
C o n c l u s i o n :
Streptococcal
Objective:
To study the rate of
infections remain an important
isolation of Streptococcus species
cause of severe disease in children
from children aged zero to 15
in Nigeria. The use of effective, safe
years, with suspected bacterial
and affordable vaccine could
infections.
significantly reduce morbidity from
M a t e r i a l s
a n d
M e t h o d s :
Laboratory records of results of
these infections, thus suggesting the
bacteriological studies of samples
need for more studies to conclude
from children with suspected
o n
s t r e p t o c o c c a l
v a c c i n e
bacterial infections in University
deployment.
of Abuja Teaching Hospital from
January 2008 through December,
K e y
w o r d s : Streptococcal
2010 were retrieved and analyzed
infections, Nigeria, Streptococcal
for bacterial growth. Data analysis
vaccines
Introduction
in developing countries like Nigeria. The
predominance of Streptococcus pneumoniae in the
The genus Streptococcus comprises of more than 30
causation of invasive diseases has lead to the
species. Streptococcus
pneumoniae , group A
advocacy of inclusion of pneumococcal vaccine in
the National Programme on Immunization.
2
Streptococcus and group B Streptococcus are the
most common causes of human streptococcal
However, there is paucity of data in Nigeria on the
infections.
1
These organisms are among the
burden of streptococcal infections in children thus
commonest bacterial causes of childhood morbidity
making the debate for vaccine deployment
inconclusive
137
It is hopeful that data generated from this study may
Statistical analysis
offer ample evidence for the need for streptococcal
vaccine inclusion in national immunization
Statistical analysis was done using Epi Info software
programmes.
version 3.5.1(CDC, Atlanta, GA, USA, 2008).
Frequency tables were generated while Chi square
and Fischer's exact tests were used to test associations
between categorical variables. Statistically
Objective
significant difference level was set at p < 0.05.
To study the rate of isolation of Streptococcus
species from children aged zero to 15 years, with
suspected bacterial infections.
Results
A total of 2,247 samples were received during the
study period, of which 918 were blood samples, 400
Materials and Methods
were urine, 292 were stool, 226 were cerebrospinal
fluid, 19 were sputum, 344 were swabs from various
The study was retrospective, on bacteriological
body sites, 43 were aspirates while 5 specimens were
samples from children aged 15 years and below that
not properly labeled to reveal their site of origin. Of
were evaluated for suspected bacterial infections at
the 1,247 (55.5%) specimens that yielded growths,
the Paediatric Department of University of Abuja
1,234 yielded 1,242 bacteria while 13 yielded 13
Teaching Hospital, Gwagwalada, Abuja. The
candida species. Bacterial growth in 1226 samples
hospital is a tertiary institution at the centre of
was monomicrobial while 8 samples yielded
Nigeria and serves as a major paediatric referral
polymicrobial growths. The rate of bacterial yield
centre for communities in the Federal Capital
from the various samples is thus: blood - 62.6%, urine
Territory and those of the neighbouring states in
- 45.5%, stool - 43.5%, cerebrospinal fliud - 8.4%,
North central Nigeria.
swabs from various sites - 72.1%. Of the 1,242
bacteria isolated, 502 (40.4%) were Staphylococcus
Samples for bacteriological studies were processed
aureus , 232 (18.7%) were Escherichia coli and 146
as recommended by Cheesbough et al. For blood
3
(11.8%) were Streptococcus species. Table 1.
culture, 2 ml of venous blood was collected
aseptically after thorough skin preparation with 70%
Table 2 shows the rate of isolation of Streptococcus
alcohol. The blood samples were introduced into
species from the various samples analyzed. About
thioglycollate broth through a sterile needle in the
76.0% of isolates from throat swabs were
ratio of one part of blood to five parts of the broth and
Streptococcus species while 36.8% of organisms
incubated at 37 C for seven days. The cultures were
o
recovered from the cerebrospinal fluid, 36.0% of
examined daily for evidence of bacterial growth such
bacteria cultured from the sputum, 20.8% of the eye
as turbidity, clot and gas formation. In samples that
swabs isolates, 13.6% of isolates from blood and
showed such evidence, sub-cultures onto chocolate
8.3% of those recovered the ear swabs were equally
and blood agar plates were performed and incubated
Streptococcus species. Similarly, a higher proportion
at same temperature for 24 to 72 hours. Organisms
of the Streptococcus species (72.6%) were recovered
isolated were identified by conventional methods.
3
from samples taken from children aged 5 years
Smears of swabs of eye, ear, umbilical and vaginal
(Figure1).
discharges as well as those of wound and skin swabs,
cerebrospinal fluid and urine samples, were
Analysis of the contribution of Streptococcus species
inoculated on MacConkey, chocolate and blood agar
to infections in children is compared with those of
plates and incubated for 24 to 48 hours and the
other bacterial pathogens on Table 3, which show that
bacteria grown were identified using standard
Streptococcus organisms is more associated with
methods.
3
respiratory tract infections, subarachnoid space
st
Bacteriological results between 1 January 2008 and
infections and blood stream infections . Majority of
31 December, 2010 were collated and analyzed to
st
the Streptococcus species isolated (88.1%) were not
identify the pattern and distribution of bacterial
further characterized, however, Streptococcus
growth.
pneumoniae accounts for 7.5% (10), group B beta
haemolytic Streptococcus was 2.2% (3) while
anaerobic Streptococcus was 4(3.0%). Four cases of
Streptococcus pneumoniae were isolated from the
sputum, three from throat swab and one each from the
cerebrospinal fliud, pleural tap and the stool.
138
Table 1 : Distribution of isolates based on the site of isolation
Bacteria
Sources of bacterial isolates
Blo
Urin
Stoo
CS
Ey
Ear
Sput
Wou
Thro
Other
Total (%)
od
e
l
F
e
um
nd
at
s
Staphylococcus
311
64
3
6
24
27
16
17
4
30
502(40.4)
aureus
Streptococcus
78
10
1
7
10
9
9
4
11
7
146(11.8)
species
Escherichia coli
55
55
89
1
3
10
-
9
1
9
232(18.7)
Klebsiella species
46
40
7
3
7
10
4
5
2
16
140(11.2)
Pseudomonas
6
2
2
-
2
51
-
13
-
13
96(7.7)
species
79
11
25
2
1
4
-
1
-
3
126(10.1)
Other bacteria
TOTAL
575
182
127
19
47
11
29
49
18
78
1
Others refer to aspirates from joint space, pleural cavity, gastric contents, peritoneal fluid (ascites), pus and
discharges from umbilicus, vaginal as well as swabs of skin lesions and those of non-specified sites
Table 2: Rate of isolation of Streptococcus species from laboratory samples with positive bacterial growth.
SAMPLE
Number of
Number of strep
Proportion (%) of
positive cases
species isolated
strep among
N (%)
N (%)
positive cases
Blood (n = 918)
575(62.6)
78 (8.5)
13.6
Stool (n = 296)
127(43.5)
1(0.3)
0.8
Urine (n = 400)
182(45.5)
10 (2.5)
5.5
Cerebrospinal fluid (n = 226)
19(8.4)
7 (3.1)
36.8
Eye swabs (n = 66)
48(72.7)
10 (15.2)
20.8
Ear swabs (n = 129)
111(86.1)
9 (7.0)
8.3
Wound swabs (n = 57)
49(85.9)
4 (7.0)
9.5
Throat swabs (n = 19)
18(94.7)
11 (57.9)
75.9
Sputum (n = 39)
29(74.4)
9 (23.1)
36.0
Aspirates+ (n = 43)
25(58.1)
4 (9.3)
16.0
Skin swabs (n = 21)
11(52.4)
-
-
Vaginal swabs (n = 21)
11(52.4)
2 (9.5)
18.2
Umbilical swabs (n = 8)
8(100.0)
-
-
Miscellaneous** (n = 5)
3(60.0)
1 (20.0)
33.3
** Miscellaneous = Site of specimen collection was not stated in 5 of the analyzed samples.
+ refer to aspirates from joint space, pleural cavity, gastric contents, peritoneal fluid (ascites) and abscesses.
80%
70%
60%
50%
0-5 years
6-10 years
40%
11-15 years
30%
Unstated age
20%
Figure 1 : Proportion of Streptococcus
10%
species isolated from various age-groups
0%
139
Table 3 : Comparison of the contribution of Streptococcus species to those of other commonly isolated
bacteria in the causation of infection** in children.
Bacteria
Site of isolation
Blood
CSF
Ear
Resp tract
Others
(n=575)
(n=19)
(n=109)
(n=47)
(n=484)
Strep
78
7
9
20
32
(n=146)
Staph
311
6
27
20
138
(n=502)
2
χ
3.68
FET
0.03
16.79
1.52
P
0.0791
0.0125
0.8732
<0.0001
0.2149
Strep
78
7
9
20
32
(n=146)
E. coli
55
1
11
1
164
(n=232)
χ
2
33.41
FET
0.13
27.59
83.44
P
<0.0001
0.0063
0.7145
<0.0001
<0.0001
Strep
78
7
9
20
32
(n=146)
Klebsiella
46
3
12
6
73
(n=140)
χ
2
11.49
FET
0.31
6.57
26.81
P
0.0007
0.0501
0.5799
0.0104
<0.0001
CSF = Cerebrospinal fluid; Resp tract = Respiratory tract; Staph = Staphylococcus aureus ; Strep =
Streptococcus species; E. coli = Escherichia coli
** Isolation of bacteria from specimens taken from stated body sites is considered as infection of that site
+Others refer to isolates from stool, urine, eye, ear, wound and aspirates from joint space, pleural cavity,
gastric contents, peritoneal fluid (ascites), pus and discharges from umbilicus, vaginal as well as swabs of
skin lesions and those of non-specified sites
Discussion
of Onipede et al from Ile-Ife, South western Nigeria
9
and Nwadioha et al from Kano, North western
Nigeria. Differences in methodology may account
10
Streptococcal organisms are common bacterial
for this; whereas the report from Ile-Ife considered
9
agents causing childhood morbidity and mortality.
Almost all organ systems could be affected by these
only patients with deep seated infections, the present
agents and there are indications that the incidence of
study included superficial infections. Similarly, the
report from Kano, which revealed isolation of only
10
infections with these agents may be increasing. The
4
overall prevalence of streptococcal infections in the
ten cases of Streptococcus pneumoniae from 3840
present study is 11.8%. However, with further
blood culture samples, also excluded results of
categorization, 75.9% of isolates from throat swabs,
bacteriological studies of swabs of body discharges as
36.8% of organisms recovered from the
well as urine, cerebrospinal fluid and stool specimens.
cerebrospinal fluid and 36.0% of bacteria cultured
Reports are however consistent on the role of
from the sputum were Streptococcus species.
streptococcal organisms in invasive diseases.
The high isolation rate of streptococcus species from
The high isolation rate of streptococcus species from
the cerebrospinal fluid, sputum, throat swabs and
the cerebrospinal fluid, sputum, throat swabs and
blood in the present study corroborates the findings
blood specimens from children with suspected
of other researchers and emphasizes the role of
5-8
bacterial meningitis, pneumonia, pharyngitis and
streptococcal organisms in systemic infections in
septicaemia in the present study is a pointer to the
children. Although, the 11.8% streptococcal
magnitude of invasive streptococcal infections in the
infections prevalence rate in this study is lower than
area of study and suggests the need for preventive
figures from EastAfrica, it is much higher than those
5
strategies aimed at curtailing the immediate and late
140
untoward
effects
of
invasive
streptococcal
Although groupAand group B streptococcal vaccines
Infections.
Although
retrospective
analysis
of
are at various stages of development, pneumococcal
bacteriological samples may not be the best indicator
vaccine has been licensed for use in children and have
of the burden of bacterial infections in a community,
been shown to be associated with a 98% reduction in
they nevertheless, give a clue to the magnitude of
rates of bacteraemia and meningitis and a 67%
morbidity caused by pathogenic organisms and the
reduction in rates of otitis media due to vaccine
serotypes.
12
distribution of the various agents among susceptible
Since it was marketed in 2000,
individuals.
In
resource-limited
countries,
widespread use of this vaccine in developed countries
retrospective analysis may be the main source of
has caused a dramatic decline in the incidence of
aetiological information as bacteriological data from
invasive pneumococcal disease among infants and
children.
12
community settings are not readily available due to
lack of laboratory and culture facilities in most
primary and secondary health facilities.
8
The high cost of conjugate pneumococcal vaccine
(approx US $50 per dose) and the challenges of
From the result of the present study, one may
developing effective and safe vaccines against group
speculate that the control of streptococcal infections
A and group B streptococci makes it unaffordable for
all but the wealthiest of countries,
13,14
in children may drastically reduce the burden of
thus for low-
bacterial meningitis, bacterial pneumonia, bacterial
income countries to introduce such vaccines, there
pharyngitis,
septicaemia
and
possibly,
the
has to be a strong political commitment. Going by the
postinfectious syndromes of acute rheumatic fever
burden of streptococcal infections in the present
and glomerulonephritis.
study, under-five morbidity is unlikely to reduce
significantly without concerted efforts at the control
The
experience
over
the
years,
of
national
of
streptococcal
infections;
hence
introducing
immunization
programs,
demonstrates
that
vaccines
against
streptococcus
species,
though
immunization is one of the effective public health
expensive, may be lifesaving and cost-effective.
strategies. Rapid deployment and use of traditional
Further studies are therefore recommended on disease
vaccines against childhood killer diseases have been
burden and the cost implication of streptococcal
the most important contributors to reductions in child
vaccines in developing countries.
mortality
and
increased
life
expectancy
in
developing countries.
11
However, introducing new
vaccines into the National Program on Immunization
requires enormous human and financial resources
Conclusion
including
engagement
of
national
leaders
responsible for primary health care services and
The
contribution
of
streptococcal
infections
to
presenting them with evidence on the burden of the
morbidity in children is enormous. Introduction of
disease and the potential impact of new vaccine
effective, safe and affordable streptococcal vaccine
introduction.
11
could
significantly
alter
the
current
pattern
of
childhood
morbidity
and
thus
warrants
further
exploration.
References
1.
Gerber MA. Non-group A or
4. Falade AG, Lagunju IA,
6. Feiklin DR, Jagero G, Aura
B Streptococci. In: Behrman
Bakare RA, Odekanmi AA,
B, et al. High rate of
RE, Kliegman RM, Jenson
Adegbola RA. Invasive
pneumococcal bacteremia in
HB (eds). Nelson Textbook
pneumococcal disease in
a prospective cohort of older
of Pediatrics, 17
th
edition.
children < 5 years admitted to
children and adults in an
Philadelphia:
Saunders,
urban hospitals in Ibadan,
area of high HIV prevalence
2004; 883-4.
Nigeria. Clin
Infect
Dis
in rural western Kenya.
2. Pneumonia: Paediatricians
2009; 48 (Suppl): S190-6.
BMC infectious Disease
advice government on
5.
Mudhune S, Wamae M.
Report on invasive disease
2010; 10: 186-94.
vaccine. This Day 2010; 15
and meningitis due to
7. Hortal M, Camou T, Palacio
(No 5689): 44.
Haemophillus influenza and
R, Dibarboure H, Garcia A.
3.
Cheesbough M. Culture
Streptococcus pneumonia
Ten-year review of invasive
media. In: Cheesbough M
from the network for
pneumococcal diseases in
(ed). District Laboratory
s u r v e i l l a n c e
o f
children and adults from
P r a c t i c e
i n
Tr o p i c a l
pneumococcal diseases in the
Uruguay: clinical spectrum,
Countries. Book 2. London:
East African Region. Clin
serotypes, and, antimicrobial
Cambridge University Press,
Infect Dis 2009; 48(Suppl):
resistance. Int J Infect Dis
1998
S147-52.
2000; 4: 91-5.
141
8. Zaidi AKM, Thaver D, Ali SA,
1 1 . A n d r u s
J K ,
D i e t z
V,
K h a n
TA .
P a t h o g e n s
Fitzsimmons J, Castillo-
13. World Health Organization.
associated
with
sepsis
in
Sol ό rzano C. Accelerating
Group
A
streptococcal
newborns and young infants
vaccines in developing
v a c c i n e
d e v e l o p m e n t :
in
developing
countries.
countries. Harvard
Health
current status and issues of
Pediatr Infect Dis J 2009
Policy Review 2006; 7 : 91-
relevance to less developed
(Suppl); 28 : S10-18.
101.
c
o
u
n
t
r
i
e
s
.
9.
Onipede AO, Onayade AA,
12. Centers for Disease Control
W H O / F C H / C A H / 0 5 . 0 9 ,
Elusiyan JBE, et al. Invasive
and Prevention. Direct and
2005;1-24.
b a c t e r i a
i s o l a t e s
f r o m
indirect
effects
of
routine
14.Bronze MS, Dale JB. Progress
c h i l d r e n
w i t h
s e v e r e
vaccination of children with
in
the
Development
of
infections
in
a
Nigerian
7-valent conjugate vaccine on
Effective Vaccines to Prevent
hospital. J Infect Dev Ctries
i n c i d e n c e
o f
i n v a s i v e
Selected
Gram-Positive
2009; 3 : 429-36 .
pneumococcal diseaseUnited
Bacterial
Infections.
Am
J
10. Nwadioha SI, Nwokedi
States
1998-2003.
MMWR
Med Sci 2010; 340: 21825.
EOP, Odimayo MS, Okwori
2005; 54 : 893.
EE, Kashiru E. Bacterial
isolates in blood cultures of
children with suspected
septicaemia in a Nigerian
Tertiary Hospital. Intern J
Infect Dis 2010; 8 :1-5.