Group B streptococcal infections

Survival and biofilm formation by Group B streptococci in simulated vaginal fluid at different pHs

The Group B Streptococcus (GBS, Streptococcus agalactiae) is an important cause of neonatal and maternal infection. GBS is a commensal organism of the lower gastrointestinal and vaginal tract. A frequent mode of neonatal infection is vertical transmission from pregnant women to their foetus or neonate. The aim of this study was to evaluate the survival and biofilm production of 10 GBS strains in simulated vaginal fluid at pH 4.2, 5.5 and 6.5. GBS survived longer at higher pH than at normal vaginal pH. At pH 4.2, with the exception of two isolates that were recovered up to 48 and 72 h, viable GBS numbers declined below the limit of detection by 24 h. At higher pH, GBS survived between 3 and 15 days. All isolates investigated were biofilm producers but biofilm production was greater in tryptone soy broth compared to simulated vaginal fluid. The quantity of biofilm produced increased with the rise in the pH. This study suggests that high vaginal pH may influence both GBS survival and biofilm production and thus could be a risk factor for GBS infection.

Emerging gram-positive bacterial infections

Over the last several decades, a number of previously known or newly described species of gram-positive bacteria have emerged as important human pathogens, particularly in industrialized countries. These microbes have demonstrated an impressive ability to produce an array of striking infectious diseases never before seen or only infrequently encountered in the past. Despite aggressive therapeutic intervention, many of these conditions portend significant morbidity and mortality. Diseases caused by members of the Staphylococcus and Streptococcus genera have figured prominently in this regard, with Staphylococcus aureus, S. epidermidis, Streptococcus pyogenes, and other beta-hemolytic streptococci being regarded as the most important species. This review focuses on the clinical and microbiologic aspects of key emerging infections caused by this group of microorganisms.