DIAGNOSIS Streptococcus pseudoporcinus
Streptococcus pseudoporcinus is a β-Hemolytic Streptococcus with a wide-zone of hemolysis first described in 2006 (1). Bekal et al observed genetic and biochemical differences between S. porcinus strains that infected humans and animals. After sequencing using 16S r RNA, they determined that these strains were actually different organisms.
Streptococcus pseudoporcinus can be confused with Group B Streptococcus (Streptococcus agalactiae) which is also β-Hemolytic, CAMP positive, bacitracin resistant, and cross-reacts with reagents in some Group B Lancefield typing kits. More confusingly, Streptococcus pseudoporcinus has mostly been isolated from the female genital tract. However, unlike Group B Streptococcus, Streptococcus pseudoporcinus has a wider band of hemolysis and a slightly different biochemical profile (see Figure 5 and Table 2). Additionally, Streptococcus pseudoporcinus has not been associated with neonatal sepsis. In a small study from Canada, Streptococcus pseudoporcinus has been associated with chorioamnionitis and preterm delivery (2). Interestingly, these women were almost exclusively immigrants from the Caribbean islands or Africa.
Contributed by Rebecca Ocque, MD and William Pasculle, MD