The Unexpected Streptococcus

• Published in: Access microbiology 2020-02, Vol.2 (2)
• Main Authors: Casha, Ramon, Gerada, Alessandro, Folb, Jonathan, Sammut, Hannah
• Format: Article
• Language: English
• ISSN: 2516-8290; 2516-8290
• DOI: 10.1099/acmi.fis2019.po0185

We report a case of Abiotrophia defectiva blood stream infection in a 45 year old male, renal transplant patient. Abiotrophia defectiva is a Gram positive coccus, classified as a nutritionally variant streptococcus secondary to its fastidious growth and culture media requirements. Further testing using the Staph aureus streak method exhibited satellitism, characteristic of this class of streptococci. This species is associated with endovascular infection with high rates of embolization and treatment failure secondary to its inherent resistance to antibiotics. Despite culturing Abiotrophia defectiva from four blood cultures we could not confidently prove underlying endocarditis despite repeated trans-oesphageal echocardiograms separated one week apart. The patient also reported the presence of a PTFE aorto-venous (AV) graft in situ and a brachiocephalic stent which was inserted 4 years ago following complications post-renal transplant insertion. This led to further investigation with FDG PET-CT to help ascertain any possible underlying source of infection. The only tracer uptake was exhibited in this patient’s PTFE AV graft. This prompted surgical removal of the AV graft which did not culture Abiotrophia defectiva. 16S PCR detected the presence of Staphylococcus epidermidis but was unable to detect Abiotrophia. A pragmatic antibiotic regime of 4 weeks of IV Benzylpenicillin 2.4g 4 hourly was used. Gentamicin was avoided in view of his history of renal transplant. A further four week course of oral high dose Amoxicillin was prescribed. Despite this unorthodox antibiotic therapy the patient remains well two months after cessation of therapy.