CP 1 - From contaminant to culprit: Corynebacterium striatum causing prosthetic valve endocarditis in a paediatric patientic patient

Priyaranganie WKAP, Denipitiya DTU, Abeysinghe SK  , District General Hospital, Hambantota

Abstract

Introduction

Corynebacterium striatum is increasingly recognised as an opportunistic pathogen, although it has traditionally been regarded as a skin contaminant. While frequently disregarded in blood cultures, its role in causing severe infections—particularly in patients with prosthetic material or structural heart disease—is becoming more evident. We report a case highlighting its clinical significance in a high-risk paediatric patient.

 Case Report

A 12-year-old boy with complex congenital cyanotic heart disease (transposition of the great arteries) was admitted in November 2025 with a six-day history of high-grade fever, poor oral intake, and generalized weakness. He had undergone patent ductus arteriosus ligation five months previously.

On admission, he was febrile, with leukocytosis (WBC-15,900/mm³), elevated C-reactive protein (329 mg/L).  The initial blood culture became positive for Corynebacterium spp. after 11 hours of incubation before starting empirical ceftriaxone. As the isolate was initially considered a possible contaminant, the laboratory recommended repeating two blood cultures. Both cultures subsequently yielded the same organism with an identical antimicrobial susceptibility pattern after approximately 12 hours of incubation. Intravenous vancomycin was added.

A previous echocardiogram performed five months earlier had shown no vegetations. However, repeat echocardiography on admission demonstrated masses attached to both mitral valve leaflets, consistent with infective endocarditis.

This was identified as Corynebacterium striatum by the reference laboratory using the BD Phoenix identification and susceptibility system. It was susceptible to vancomycin and erythromycin, intermediately susceptible to penicillin, and resistant to cotrimoxazole

Although the patient initially improved and follow-up blood cultures became sterile, he later developed hospital-acquired pneumonia with newly developed fever. Intravenous ceftriaxone was discontinued, and meropenem was commenced while continuing vancomycin. Following this modification, fever spikes resolved and inflammatory markers decreased. Vancomycin was administered for six weeks. A subsequent follow-up echocardiogram demonstrated healing vegetations. The patient made a full clinical recovery and was discharged.

 Discussion

Although Corynebacterium species are often regarded as blood culture contaminants, repeated isolation of the same organism from multiple cultures indicated true infection. The combination of persistent positive blood cultures and echocardiographic vegetations fulfilled the modified Duke criteria for definite endocarditis. Vancomycin remains the treatment of choice.