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.