Abstract:

Introduction: Group B streptococcus and Listeria monocytogenes are members of the normal flora of the female genital tract. During labour GBS and Listeria monocytogenes may infect the newborns, leading to neonatal sepsis and meningitis. GBS has become the major cause of bacterial infections in the peri-natal period, including bacteremia, amnionitis, endo metritis and urinary tract infection in pregnant women. Listeria monocytogenes can lead to abortion, stillbirth or delivery of an acutely ill infant. Rates of GBS colonization vary widely throughout the world due to differences in laboratory investigation methods, regional variations and racial differences. So far, there is no report on prevalence of GBS and Listeria monocytogenes among pregnant women in Mwanza.

Objectives: To establish the prevalence of maternal vaginorectal colonization by group B Streptococcus (GBS) and Listeria monocytogenes, susceptibility pattern and associated risk factors among pregnant women attending Bugando Medical Centre and Igombe Health Centre.

Methods: The study was a cross section conducted between 1st November 211 to 31st May 2012 in two health facilities, Bugando Medical Centre and Igombe Health Centre. We recruited 295 pregnant women between 28-42 weeks of gestation who had visited for antenatal care. Demographic information and obstetric history of participants were collected using standardized questionnaire. Vaginal and rectal swabs were obtained and cultured on 5% sheep blood agar and susceptibility testing done using disk diffusion technique.

Results: GBS strains were isolated from twenty eight out of 295 pregnant women corresponding to the prevalence of 9.49% of the 28 patients carrying GBS, thirteen isolates were cultured from only vaginal swabs (4.41%), only from rectal swabs in ten cases (3.39%), from both vaginal and rectal swabs in five cases (1.69%). Listeria spp were isolated in two pregnant women corresponding to the prevalence of 0.68%. One isolated from the vaginal swab and the other from the rectal swab. All GBS and Listeria spp isolates were sensitive to penicillin and ampicillin. Eight GBS isolates were resistant to erythromycin (28.6%), seven GBS isolates were resistant to clindamycin (25%) and fifteen GBS isolates were resistant to tetracycline (53.6%). One listeria spp isolate was resistant to cotrimoxazole. Pregnant women with no formal education and dwelling in rural areas were more frequently colonized by GBS.

Conclusions: The prevalence of GBS in our study population was 9.49% while the prevalence of Listeria spp colonization is 0.68%. Majority of the GBS isolates were resistant to tetracycline, erythromycin, and clindamycin. All GBS and Listeria spp isolates were sensitive to penicillin and ampicillin.

Recommendations: We recommend antenatal screening of GBS in our study population at 35-37 gestation weeks as recommended by CDC. There is the need to do routine laboratory antimicrobial susceptibility screening due to emerging resistance to antibiotics (tetracycline, erythromycin and clindamycin). Further cohort studies to explore the prevailing serotypes and unexplored variables need to be done.