Final Diagnosis -- Streptococcus pseudoporcinus

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.

Figure 5: Streptococcus agalactiae (on left) and Streptococcus pseudoporcinus (on right) on 5% Sheep Blood agar

* Data taken from Duarte et al, 2005. + Data taken from Bekal et al, 2007. ++ Data taken
from Gaudreau et al, 2007. ** Data taken from lab strains of Streptococcus agalactiae
and patient's sample of Streptococcus pseudoporcinus.


  1. Bekal S, Gaudreau C, Laurence RA, Simoneau E, Raynal L. Streptococcus pseudoporcinus sp. nov., a novel species isolated from the genitourinary tract of women (2006). Journal of Clinical Microbiology; 44(7):2584-6
  2. Gaudreau C, Simoneau E, Labrecque O, Laurence RA, Laferrière C, Miller M, Raynal L, Rallu F. Epidemiological, biochemical and antimicrobial susceptibility characteristics of Streptococcus pseudoporcinus isolated in Quebec, Canada, from 1997 to 2006 (2007). Journal of Medical Microbiology; 56(Pt 12):1620-4
  3. Duarte RS, Barros RR, Facklam RR, Teixeira LM. Phenotypic and genotypic characteristics of Streptococcus porcinus isolated from human sources (2005). Journal Clinical Microbiology; 43(9):4592-601

Contributed by Rebecca Ocque, MD and William Pasculle, MD

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