A rare occurrence of Serratia rubidaea in a patient with ear discharge

Isolation and Characterization of a Serratia rubidaea from a Shallow Water Hydrothermal Vent

Microbial life present in the marine environment has to be able to adapt to rapidly changing and often extreme conditions. This makes these organisms a putative source of commercially interesting compounds since adaptation provides different biochemical routes from those found in their terrestrial counterparts. In this work, the goal was the identification of a marine bacterium isolated from a sample taken at a shallow water hydrothermal vent and of its red product. Genomic, lipidomic, and biochemical approaches were used simultaneously, and the bacterium was identified as Serratia rubidaea. A high-throughput screening strategy was used to assess the best physico-chemical conditions permitting both cell growth and production of the red product. The fatty acid composition of the microbial cells was studied to assess adaptation at the lipid level under stressful conditions, whilst several state-of-the-art techniques, such as DSC, FTIR, NMR, and Ultra-High Resolution Qq-Time-of-Flight mass spectrometry, were used to characterize the structure of the pigment. We hypothesize that the pigment, which could be produced by the cells up to 62 °C, is prodigiosin linked to an aliphatic compound that acts as an anchor to keep it close to the cells in the marine environment.

Bacteremia due to Serratia rubidaea in intensive care unit: a case series

INTRODUCTION

Bacteremia caused by Serratia rubidaea is seldom mentioned in comparison with other Enterobacteriaceae species. It primarily affects immunocompromised patients undergoing invasive procedures. Furthermore, the incidence, clinical features, and microbiological profile of this pathogen in the intensive care unit are rarely described.

CASE PRESENTATION

We present four North African case studies of bacteremia in four young female patients admitted to the intensive care unit for ketoacidosis with a history of diabetes mellitus. All four patients developed catheter-related infections complicated by deep vein thrombosis. The catheter site was femoral in all cases, and the main clinical manifestation was poorly tolerated fever. The pathogen was isolated in multiple peripheral blood cultures (> 4) for each patient, showing a similar profile in all cases: resistance to third-generation cephalosporins and sensitivity to aminoglycosides, piperacillin, fluoroquinolones, and folate-pathway inhibitors. Targeted treatment consisted of a combination of ciprofloxacin 400 mg twice per day and trimethoprim/sulfamethoxazole 400/80 mg thrice per day for all four cases. However, in one case, this regimen was switched to amikacin due to adverse effects. The outcomes were favorable in the majority of cases. The patients described in this study were 21, 66, 22, and 27-year-old North African women.

CONCLUSION

Most of the reported cases shared common risk factors and clinical aspects. Notably, a case of thrombosis complicating a catheter infection caused by Serratia rubidaea has not been previously reported in the literature. Furthermore, this bloodstream infection typically affects deeply immunocompromised patients. However, our four cases, admitted to the intensive care unit for ketoacidosis, only had a history of diabetes mellitus.