Browsing by Author "Bahez, Ayesha"

Group B streptococcus (GBS) is a leading cause of maternally-acquired invasive infections in neonates. Nowadays maternal immunization with GBS vaccine is of utmost demand for the prevention of these infections. Required knowledge concerning vaccine candidates includes serotype-specific polysaccharides and GBS virulence proteins. This information is required to plan the best preventative strategy. No vaccine is yet available, but two vaccine candidates are investigated in clinical trials, the protein subunit and capsular polysaccharide conjugate vaccines. The common serotypes of GBS isolates from asymptomatic and symptomatic pregnant women differ in different geographical areas and need to be elucidated. In this project, we aimed to undertake capsular serotyping and virulence factor genes identification for the local GBS isolates as a pilot study to identify vaccine candidates. This is a descriptive lab-based study to determine the GBS different serotypes and the presence of the genes for virulence factors bca and rib in the isolates obtained from symptomatic pregnant women in Hospital Tengku Ampuan Afzan (HTAA), Kuantan, Pahang, Malaysia. Standard microbiological methods, according to the Centers for Disease Control and Prevention (CDC) recommendations, were used to identify GBS serotypes. A total of 62 GBS isolates from high vaginal swabs of symptomatic pregnant women were collected from the 1st of March 2018 to 30th of July 2018. The isolates identity was reconfirmed by molecular methods. Latex Agglutination test was performed to determine the GBS serotypes according to the specificity of the capsular polysaccharide. Of the 62 examined GBS isolates, 48 were serologically typeable, representing (77.4%), and 14 were serologically non-typeable representing (22.6%) of the samples. Serotype Ia and Ib (16.1% each) was the most common capsular types, followed by II, V, and VII (9.7% each), III (8.1%), VI (6.5%), and VIII (1,6 %). Among all ten GBS serotypes, serotypes IV and IX were not detected in the present study. Real-time PCR revealed that 42 (67.7%) isolates harboured the rib gene while 61 (98.4%) isolates harboured the bca gene. Our findings showed that the five widely known prevalent serotypes in other regions in the world which are considered as candidates for pentavalent CPS-conjugate vaccine do not match the CPS distribution in symptomatic pregnant women in Kuantan. On the other hand, the frequency of virulence genes rib and bca is higher in our isolates, which tentatively makes the proteinaceous vaccine, N-terminal domains of Rib and AlpC a more suitable choice for GBS prevention in this geographical area. However, further wider study recruiting larger number of isolates from various Malaysian states is required to confirm this conclusion.