Background: Streptococcus pseudoporcinus (S. pseudoporcinus) was first identified in 2006. It cross-reacts with Lancefield group B antigen agglutination reagents and has been misidentified as S. agalactiae. Sites of S. pseudoporcinus isolation include the female genitourinary tract, urine, wounds, and dairy products. The prevalence of vaginal colonization is reportedly between 1 and 5.4%. Two uneventful cases of soft tissue infection caused by S. pseudoporcinus were reported in the past. However, since late 2019, six cases of invasive S. pseudoporcinus infections have emerged in the literature, one of which was fatal.
Case presentation: We describe a fatal case of a Caucasian male with spontaneous bacterial peritonitis associated with bacteremia due to a multidrug-resistant S. pseudoporcinus strain in a patient with decompensated liver cirrhosis. Despite the patient's good general condition and stable blood test results when he had visited the outpatient clinic for large-volume paracentesis a few days before admission, this time he presented to the emergency department with a rapidly worsening clinical condition and with laboratory features consistent with multiple-organ dysfunction syndrome, and succumbed within a short period.
Conclusions: Contrary to what was thought until recently, multidrug-resistant S. pseudoporcinus may cause invasive, disseminated, fatal disease in humans. According to current limited data, vancomycin, linezolid, daptomycin, levofloxacin, clindamycin, and tetracycline seem to be the most effective antimicrobial agents against multidrug-resistant strains, and should be the empirical choice in cases of disseminated S. pseudoporcinus infection until laboratory antimicrobial susceptibility results are available. Improvements and new approaches for bacterial identification in routine clinical microbiology laboratories may reveal the real spectrum of S. pseudoporcinus infections in humans, which is currently believed to be underestimated. SS. pseudoporcinus could emerge as a serious medical problem in the near future, similar to other β-hemolytic streptococci.
Keywords: Fatal infection; Group B streptococci; Multidrug-resistant strain; Spontaneous bacterial peritonitis; Streptococcus pseudoporcinus.