4. DISCUSSION
Group B streptococcus colonisation among pregnant women commonness
worldwide is highly variable (2.0%-32.0%)1,
depending on regions. In this study, the prevalence of GBS colonisation
was 8.69%, which is higher than those reported in previous studies in
other regions of Cameroon; including 4% in a tertiary hospital
in Cameroon13, 7.7% at the Yaoundé Gyneco-obstetric
and Paediatric hospital15 and 6,7% at the Yaoundé
General Hospital16. Variations between regions could
possibly be due to differences in sampling method used, sample size,
population variation and geographical difference. However this result is
simillar to the 8.5% repported in Ethiopia 17 but
higher than the 4.9% reported in a hospital-based study and
implications for primary care Shenzhen, China 18 and
lower than 19.5% reported in Amman, Jordan 19, 13.7%
repported by Mekelle, 20.86% by Hawassa and 19% by Jimma with overall
all in Ethiopia 20, 21, 22 and the 28.8% determined
in Uganda23. These variations between countries could
be due to differences in culture methods, populations investigated,
sample size and sampling sites. For example, the prevalence of GBS
sampled from anogenital was hight in Uganda (28.8%)23and sampled from both abdominal skin and ear canal was high in Italy
(62.7%) and in Gambian (33.7%) 24,25 but the
prevalence of GBS sampled only from skin/mucosal surface was low in
Pakistan (8.5%) and in Greece (6.6%), 26,27indicating potential differences in GBS colonisation according to the
sites of sample collection. It should be noted GBS screening is not a
standard care for maternal GBS colonisation during pregnancy and
increases the risk of neonatal infection by vertical
transmission28. The susceptibility to antibiotics has
shown that antibiotic prophylaxis could effectively interrupt vertical
transmission of GBS and reduce the incidence of GBS infections.
Therefore, these findings recommend the need for screening of pregnant
women for GBS, so that intrapartum antimicrobial prophylaxis be offered
to all GBS-colonised women.
Studies conducted in Cameroon on GBS colonisation in pregnant women have
focused on assessing the prevalence12, 13, 15, 16, 19but risk factors for GBS colonisation have not been systematically
studied. For example, increasing epidemiological studies have
demonstrated the relationship between obesity and GBS colonisation in
pregnant women 1, 23. The impact of sociodemographics
factors on GBS colonisation in pregnant women show the association with
the level of income (p = 0006) with high prevalence (55.56%) found in
patients with low income. This could be due to personal hygiene and
environmental sanitation difference between low and high-income
settings. The difference may also be related with awareness and
behavioral variation. However, in two studies conducted in Zimbabwe
showed significant association of GBS colonization among rural residents
compared to urban residents29.
The impact of obstetric factors on GBS colonisation in pregnant women is
still uncertain since previous results are
inconsistent1. Several studies revealed no significant
differences in colonisation rates according to ectopic pregnancy, induce
labour, PROM and used of contraceptive30, 31, 32, 33,
34 as shown in our results. In some research showed increasing age was
significantly associated with lowering rates of GBS
colonisation35,36. The study from a hospital-based
study and implications for primary care revealed that pregnant women had
a significantly higher colonisation rate1. This
corroborate the current findings, eventhough the association was not
significant with higher rates of colonisation in the multivariable
model. Therefore, these inconsistent results may be influenced by many
different cut-off points of gestational age and various structures of
the model fitted. However, parity, induced abortion, spontaneaous
abortions, stillborn, number of prenatal visits were significantly
associated with rates of colonisation in our research. This result is
comparable to the result determined in pregnant women in northern
India37 and also with the study conducted by Dechen TC
et al38.
Disease history is potential risk factors for GBS colonisation in
pregnant women39,40. A study in Korea on pregnant
women revealed that urinary tract infection and vaginitis were
significantly associated with GBS colonisation30.
Another study in Bukavu also found that both urinary tract infections
and HIV seropositivity were associated with higher odds ratios for
vaginal colonisation in pregnant women39. However, our
study found that, HIV seropositivity and UTI during pregnancy were
protective factors for GBS colonisation (OR = 0 and 0.51 successively
for HIV and UTI patients). Similar were also shown from a hospital-based
study and implications for primary (1). Induced
abortion (odds ratio [OR] = 3.09, 95% CI 1.56-6.21),
spontaneaous abortions (OR= 2.82, 95% CI 1.14-7.29), stillborn
(OR= 7.75, 95% CI 2.61-21.71), fever (OR= 0.37, 95% CI
0.19-0.71) and anemia (OR = 0.22, 95% CI 0.12–0.43).
The potential reasons for these results remain unclear. The underlying
biological mechanism and aetiology for these risk factors associated
with GBS colonisation is still uncertain. Genitourinary GBS colonisation
may occur with respect to hygiene, sexual practice or underlying immune
system polymorphisms that reduce innate ability to eliminate the
organism 41, 42. Future study examines women who are
originally negative and then become positive is needed, which may
improve our understanding of the risk factors for colonisation.
Results of antibiotic susceptibility testing revealed that almost all
strains (89%) were sensitive to all penicillins G tested. However
highest levels of resistance were recorded with gentamicin (100%) and
clindamycin (100%). Whereas the higher intermediate activity where
found with streptomicin (64%), Pristinamici (44%) and Rifampicin
(38%). These results showed that beta-lactamines known to be used as
ich constitute the recommended first and second line prophylaxis
regimen43 were all active on the isolated strains.
However, Erythromycin which is recommended in case of allergy to
beta-Lactamines was not active on some strains. Similar results were
reported by Shiferawu et al . in South Ethiopia with 100%
susceptibility of strains to Penicillin G44.
To our knowledge, it is the largest sample studies on this topic in
Cameroon to date, and this study provides new insights into the
interfering factors associated with GBS colonisation among pregnant
women. However, potential limitations also need to be considered. First,
only the vagina was used as a sampling site, with a consequence of
underestimation of the true prevalence of GBS. However, the latest
system review on pregnant women revealed that there was no significant
difference in GBS colonisation according to sample sites (11% for both
vaginal and rectal samples, 11% for vaginal samples, and 8% for other
samples, P = 0.070) 44. Second, the study design is a
cross-sectional, in which both cause and effect are measured at the same
time; therefore, we can only describe associations between influencing
factors and GBS colonisation, not a causal conclusion. The
pathophysiological mechanisms responsible for the observed associations
are unknown, therefore results from this study need to be confirmed in
future longitudinal studies. Finally, although it is one of the large
sample studies in Cameroon, it only represents data from one hospital in
one city. Results from this study need to be verified in future
prospective, national, multihospital and multicenter research.