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Most cases of mediastinal abscess occur as a postoperative complication of a thoracic surgical procedure or following trauma. The most common causative microorganism is Staphylococcus aureus, but it can be rarely caused by unusual microorganisms, such as Gemella species. These are relatively difficult-to-identify commensal microorganisms of the upper respiratory and gastrointestinal tracts and may cause several infections. A 66-year-old man was diagnosed with Gemella bergeri mediastinal abscess by the molecular detection of bacterial genes. He was successfully treated with penicillin antibiotic for eight weeks. To our knowledge, this is the first case report of mediastinal abscess caused by G. bergeri.

Background Gemella bergeri is one of the nine species of the genus Gemella and is relatively difficult to identify. We herein describe the first case of septic shock due to a Gemella bergeri coinfection with Eikenella corrodens. Case presentation A 44-year-old Asian man with a medical history of IgG4-related ophthalmic disease who was prescribed corticosteroids (prednisolone) presented to our hospital with dyspnea. On arrival, he was in shock, and a purpuric eruption was noted on both legs. Contrast enhanced computed tomography showed fluid retention at the right maxillary sinus, left lung ground glass opacity, and bilateral lung irregular opacities without cavitation. Owing to suspected septic shock, fluid resuscitation and a high dose of vasopressors were started. In addition, meropenem, clindamycin, and vancomycin were administered. Repeat computed tomography confirmed left internal jugular and vertebral vein thrombosis. Following this, the patient was diagnosed with Lemierre’s syndrome. Furthermore, he went into shock again on day 6 of hospitalization. Additional soft tissue infections were suspected; therefore, bilateral below the knee amputations were performed for source control. Cultures of the exudates from skin lesions and histopathological samples did not identify any pathogens, and histopathological findings showed arterial thrombosis; therefore it was concluded that the second time shock was associated with purpura fulminans. Following this, his general status improved. He was transferred to another hospital for rehabilitation. The blood culture isolates were identified as Gemella bergeri and Eikenella corrodens. Gemella bergeri was identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry and confirmed by 16S rRNA gene sequencing later. The primary focus of the infection was thought to be in the right maxillary sinus, because the resolution of the fluid retention was confirmed by repeat computed tomography. Conclusions Gemella bergeri can be the causative pathogen of septic shock. If this pathogen cannot be identified manually or through commercial phenotypic methods, 16S rRNA gene sequencing should be considered.

This is the first report of an orbital abscess caused by Gemella bergeri, uncommonly identified in cardiac valvular infections. Through matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS), microbial identification and speciation resulted in timely identification and appropriate management. Successful management includes accurate microbial identification, incision and drainage, and broad-spectrum antibiotics.

Gemellais a genus of Gram-positive bacteria found in the digestive tract of humans. They rarely cause systemic illness but have been recently implicated in several serious infections. We report infective endocarditis caused byGemella bergeriin a 23-year-old with a bicuspid aortic valve status post-intervention in infancy.

Only 8 cases of Gemella bergeri endocarditis have been reported in literature. G. bergeri, a slow-growing, fastidious, gram positive cocci, is part of the normal human flora and can lead to a fulminant presentation. We describe a case of mitral valve G. bergeri endocarditis, which rapidly progressed

Gemella bergeriis a Gram-positive cocci species arranged in pairs and composes the normal flora of oral cavity, digestive and urinary tract. Several species ofGemellaare known to cause endocarditis. Here, we report the first case in Thailand ofG. bergeriendocarditis whose blood culture was negative using routine methods but was positive by PCR identification of bacteria in the affected valve. A 37-year-old male presented with prolonged fever, weight loss, and dyspnea on exertion. By transthoracic echocardiography, he was suspected of having infective endocarditis of the tricuspid valve. The patient underwent tricuspid valve repair and vegetectomy. Routine hospital blood cultures were negative butG. bergeriwas identified by PCR/sequencing of the heart valve tissue.