Mycotic Aneurysm Caused by Streptococcus constellatus subsp. constellatus

A case of aortitis and saccular aortic aneurysm caused by rare aetiological organisms, Streptococcus constellatus and parvovirus B19, and atherosclerosis

Aortitis and mycotic aneurysm are vascular conditions characterized by inflammation of the aortic wall or the presence of an aneurysm resulting from microbial infection. This is a rare case of aortic aneurysm caused by atherosclerosis, with Streptococcus constellatus and Parvovirus B19 infection, in a 60-year-old male. The patient presented with rigors and pleuritic chest pain, and was found to have a saccular aneurysm of the ascending aorta and pericardial effusion. The patient underwent urgent replacement of the ascending aorta and completed 6 weeks of antibiotics with good recovery. This case emphasizes the importance of considering rare organisms in patients with aortitis and mycotic aneurysm, particularly in cases with blood cultures without microbial growth. Early diagnosis and treatment may be essential for the prevention of life-threatening complications.

A streptolysin S homologue is essential for β-haemolytic Streptococcus constellatus subsp. constellatus cytotoxicity

Streptococcus constellatus is a member of the Anginosus group streptococci (AGS) and primarily inhabits the human oral cavity. S. constellatus is composed of three subspecies: S. constellatus subsp. constellatus (SCC), S. constellatus subsp. pharyngis and the newly described subspecies S. constellatus subsp. viborgensis. Although previous studies have established that SCC contains β-haemolytic strains, the factor(s) responsible for β-haemolysis in β-haemolytic SCC (β-SCC) has yet to be clarified. Recently, we discovered that a streptolysin S (SLS) homologue is the β-haemolytic factor of β-haemolytic Streptococcus anginosus subsp. anginosus (β-SAA), another member of the AGS. Furthermore, because previous studies have suggested that other AGS species, except for Streptococcus intermedius, do not possess a haemolysin(s) belonging to the family of cholesterol-dependent cytolysins, we hypothesized that, as with β-SAA, the SLS homologue is the β-haemolytic factor of β-SCC, and therefore aimed to investigate and characterize the haemolytic factor of β-SCC in the present study. PCR amplification revealed that all of the tested β-SCC strains were positive for the sagA homologue of SCC (sagA(SCC)). Further investigations using β-SCC strain W277 were conducted to elucidate the relationship between sagA(SCC) and β-haemolysis by constructing sagA(SCC) deletion mutants, which completely lost β-haemolytic activity. This loss of β-haemolytic activity was restored by trans-complementation of sagA(SCC). Furthermore, a co-cultivation assay established that the cytotoxicity of β-SCC was clearly dependent on the presence of sagA(SCC). These results demonstrate that sagA(SCC) is the factor responsible for β-SCC β-haemolysis and cytotoxicity.

Fatal spontaneous bacterial peritonitis and necrotizing fasciitis with bacteraemia caused by Bacillus cereus in a patient with cirrhosis

We report a case of spontaneous bacterial peritonitis and necrotizing fasciitis caused by Bacillus cereus in a cirrhotic patient without preceding disruption of skin or symptoms of gastroenteritis. This rapidly fatal infection due to B. cereus adds to the long list of aetiologies of infectious complications among patients with cirrhosis of the liver.

Rothia dentocariosa bacteremia in children: report of two cases and review of the literature

Rothia dentocariosa, a pleomorphic, fastidious, Gram-positive rod, is a normal inhabitant of the oropharynx. It is a well-known causative agent of dental plaques and periodontal disease. Generally regarded as of low virulence to humans, R. dentocariosa has been increasingly recognized as a pathogen in adults and often associated with infective endocarditis. It should not necessarily be regarded as a contaminant when the isolate comes from areas other than the oropharynx, especially from the blood. We report two cases of R. dentocariosa bacteremia, including an 8-month-old boy with repaired transposition of the great arteries, and a healthy 20-month-old girl with herpangina.