Neonatal Sepsis Caused by Multi-Resistant Streptococcus Mitis

ABSTRACT

PURPOSE: Streptococcus mitis, one of the Viridans streptococci, is a normal female genital tract flora. It is known as a common cause of chorioamnionitis and subsequent abortions in perinatal period. Although it has been suggested to be less virulent they can cause severe neonatal infections. In this study, we focused on the clinical presentations of neonatal septicemia and the antibiotic susceptibilities of Streptococcus mitis. METHODS: Nine newborns for whom Streptococcus mitis was isolated from normally sterile sites were seen in the NICU of Eulji University Hospital from Jan. 1 to Dec. 31 2005. Medical records were reviewed for the perinatal risk factors, maternal clinical manifestations, obstetric complications and the placental pathologic findings. We also observed the neonatal clinical courses and antibiotic susceptibilities of Streptococcus mitis. RESULTS: All nine infants were high-risk newborns because of prematurity, low birth weight and/or co-morbid diseases. Clinical manifestations varied from asymptomatic to severe neonatal sepsis. Six cases resistant to ampicillin were all sensitive to vancomycin. Five among them had clinical sepsis, and one infant was asymptomatic. Three cases were sensitive to ampicillin, two of them were asymptomatic and one infant with sepsis was successfully treated with ampicillin and aminoglycoside. CONCLUSION: Streptococci mitis should not be overlooked as a contaminant when isolated from normally sterile sites. If Streptococci mitis or Viridans streptococci are recovered from a high-risk newborn showing no clinical response to penicillin, it would be better to switch antibiotics to vancomycin until the susceptibility results available.