CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 9, October 2012
492
AFRICA
to 72 hours in anaerobic gas pak (Becton Dickinson, USA)
jars with appropriate controls. The organisms isolated were
further identified using conventional laboratory methods and the
identity of streptococcal isolates was confirmed using the API
Strep 20 (API, France) system.
9
The study was approved by the ethics committee of the Nelson
R Mandela School of Medicine, University of Natal, Durban.
Statistical analysis
Results in each group were arranged in a contingency table and
were analysed using Fisher’s exact test (one-tailed probability).
Since there were six comparisons, the Bonferroni correction was
applied (
p
<
0.05/6)
and a
p
-
value
<
0.0083
was taken as the
level of significance.
To analyse the difference in the occurrence of bacteraemia
between the control and antibiotic groups as well as between
the antiseptic and the antibiotic groups, the Chi-square test was
used, employing Yates’ correction for continuity. The level of
significance was taken at
p
<
0.05.
Results
One hundred and sixty black patients, 50 males and 110 females,
entered the study. The four groups were comparable with regard
to age and gender (Table 1).
In the control group, 14 (35%) patients had positive blood
cultures after dental extraction. Post-extraction bacteraemia was
detected in 16 (40%), three (7.5%) and eight (20%) patients
in the chlorhexidine, amoxicillin and clindamycin groups,
respectively. Only the differences between the amoxicillin and
control groups (
p
=
0.003),
and between the amoxicillin and
chlorhexidine groups (
p
=
0.0006)
were statistically significant
When the antibiotic groups were combined, the number of
patients with post-extraction bacteraemia differed significantly
from those in the control group (
p
=
0.014)
and in the antiseptic
group (
p
=
0.003).
The bacteria that were cultured after dental
extraction in the four groups of patients are shown in Table 2.
Discussion
In this study, we compared the efficacy of two antibiotics,
amoxicillin and clindamycin, given orally, and an oral antiseptic,
chlorhexidine, in the prevention of post-extraction bacteraemia
in adult black patients. None of these treatments was effective in
preventing bacteraemia after dental extraction.
Oral amoxicillin given prior to dental extraction produced
a significant reduction in post-extraction bacteraemia in our
patients (7.5 vs 35% in the control group). Streptococci were not
isolated in any patient in the amoxicillin group.
Shanson
et al.
compared amoxicillin with penicillin V in the
prophylaxis of post-extraction bacteraemia in two groups of 40
patients each.
10
Both drugs were given as a 2-g oral dose one
hour prior to extraction. A control group of 40 patients received
no treatment. Bacteraemia was reduced from 70% in control
patients to 25 and 20% in those who had received amoxicillin
and penicillin V, respectively. Streptococci were isolated from
the blood cultures of 40% of the control patients, 5% of the
amoxicillin patients and 12% of the penicillin V patients.
The difference between the number of patients with
bacteraemia in the control and amoxicillin groups was statistically
significant; the differences between the two antibiotic groups and
between the penicillin V and control groups were not significant.
The viridans streptococci isolated from the blood of patients in
this study were sensitive to both penicillin V and amoxicillin and
the sensitivity was similar. Serum antibiotic levels exceeded the
minimum inhibitory concentrations and minimum bactericidal
concentrations for both drugs. We did not measure serum
antibiotic levels in our study.
The use of 3 g amoxicillin given orally as prophylaxis against
bacteraemia associated with dental surgery was investigated by
Oakley
et al
.
11
They cultured bacteria in 7.1% of their 42 patients.
In a study to determine the efficacy of oral amoxicillin (50 mg/
kg body weight) given prior to dental extraction in children, 47
children were allocated to the amoxicillin group and 47 to the
control group.
12
Bacteraemia following extraction was detected
in 38% of control patients and 2% of amoxicillin patients; this
difference was statistically significant. All streptococci were
sensitive to amoxicillin and serum amoxicillin levels exceeded
the minimum inhibitory concentrations for viridans streptococci.
In another study, post-extraction bacteraemia was present in
10%
of patients treated with 3 g amoxicillin compared to 89%
of control patients; this difference was statistically significant.
13
Lockhart
et al.
administered an amoxicillin elixir 50 mg/kg to
children prior to dental extraction.
14
At 1.5 min after the initiation
of dental extraction, bacteraemia occurred in 15% of patients
who were given amoxicillin compared to 76% of patients in the
control group (
p
<
0.001).
The use of 2 g amoxicillin given orally as prophylaxis against
TABLE 1. PATIENT DEMOGRAPHICS
Control
group
(
n
=
40)
Chlorhexi-
dine group
(
n
=
40)
Amoxicillin
group
(
n
=
40)
Clindamycin
group
(
n
=
40)
Males
12
8
14
16
Females
28
32
26
24
Age (years)
Range
Mean
18–60
32.1
18–55
28.0
18–56
29.9
18–66
28.1
TABLE 2. NUMBER OF PATIENTSWITH POSITIVE CULTURES
AFTER DENTAL EXTRACTION
Organisms
Groups
Control
Chlor-
hexidine
Amoxi-
cillin
Clinda-
mycin
Streptococcus mitis
Streptococcus sanguis
Streptococcus anginosus
group
Viridans streptococci
Streptococcus pneumonia
Staphylococcus epidermidis
Enterococcus faecalis
Neisseria
species
Corynebacterium
species
Gram-negative bacilli
Moraxella
species
Peptostreptococcus
species
Prevotella melaninogenica
Eikenella corrodens
Gemella haemolysans
Mixed growth
1
4
5
1
1
1
1
1
2
2
5
3
1
2*
1
1
1
5
1
1
1
Total
14
16
3
8
*
Streptococcus sanguis + Streptococcus anginosus
group; Viridans strep-
tococci +
Neisseria
species
