First case of infective endocarditis due to NDM-type carbapenemase-producing Serratia marcescens in a preterm infant: a case report

Serratia marcescens (S. marcescens) is a Gram-negative rod-shaped bacterium belonging to the Enterobacteriaceae family, commonly found in various environments. This opportunistic pathogen can cause urinary tract infections, respiratory infections and septicaemia, but endocarditis is particularly rare and concerning due to its rapid and devastating progression. We report the first documented case worldwide of infective endocarditis (IE) caused by S. marcescens producing NDM-type carbapenemase, and the second reported case of S. marcescens endocarditis in a preterm infant. The patient was a preterm male infant born at 34 weeks of gestation, from a triplet pregnancy, admitted to the neonatal intensive care unit on day 2 of life for respiratory distress. The mother, aged 39, had undiagnosed gestational diabetes. Premature rupture of membranes had occurred 10 days before delivery, necessitating prophylactic treatment with amoxicillin. On day 4 of life, the newborn developed a fever with elevated C-reactive protein (CRP) levels and leucocytosis, leading to antibiotic therapy with colistin, imipenem and amikacin. Blood cultures revealed the presence of carbapenemase-producing S. marcescens sensitive to fluoroquinolones. A cardiac ultrasound showed a vegetation on the mitral valve, confirming the diagnosis of IE. Despite intensive treatment, the newborn died on day 16 of life due to septic shock. This rare case of endocarditis caused by S. marcescens highlights the severity of this infection in preterm infants. Treatment relies on appropriate antibiotic therapy. Prevention requires strict hygiene measures. Further research is needed to establish optimal therapeutic recommendations.