Bacillus popilliae Endocarditis with Prolonged Complete Heart Block

Infective endocarditis caused by Paenibacillus thiaminolyticus: a case report and review of literature

Background

Paenibacillus constitutes a genus of gram-positive, facultatively anaerobic, rod-shaped bacteria that act as potentially opportunistic pathogens. With only a few documented case studies to date, Paenibacillus species are rarely the cause of a disease in humans.

Case summary

We report a case involving a 64-year-old male with known mild mitral regurgitation, who presented with fever and dyspnoea. Initially treated with empirical antibiotics, his blood cultures cultivated Paenibacillus thiaminolyticus, a previously unreported cause of endocarditis. Transoesophageal echocardiography demonstrated vegetations on the both leaflets of mitral valve along with severe mitral regurgitation, thus confirming a diagnosis of endocarditis. The patient was referred for cardiac surgery; however, the procedure was delayed due to complications related to a known hepatic cyst and additionally contraction of COVID-19 infection. The patient subsequently underwent mitral valve replacement without complications.

Discussion

Because of its rarity, guidelines to recommend specific antibiotics to treat Paenibacillus infective endocarditis are absent. To confirm the pathogen, molecular methods such as mass spectrometry or 16S rRNA sequencing are required. Early targeted antibiotic therapy and cardiac surgery are warranted to achieve good clinical outcomes.

A Case of Paenibacillus pasadenensis Bacteremia in a Patient with Acute Respiratory Distress Syndrome after Microsurgical Clipping

We report the first case of bacteremia by a novel Paenibacillus species, Paenibacillus pasadenensis, from a 55-year-old male patient with acute respiratory distress syndrome, following a microsurgical clipping procedure of a ruptured intracranial aneurysm. The bacterium was identified using 16S rRNA gene sequencing analysis, which was applied because current conventional methods employed in the clinical microbiology laboratory proved unsuccessful. Since this bacterium was first identified in 2006 and has never been reported elsewhere, we believe this report can provide practitioners with useful insight on the pathogenicity of this species.

Cardiac device-related endocarditis caused by Paenibacillus glucanolyticus

We report the first case of Paenibacillus glucanolyticus infection in a 65-year-old patient with type 2 diabetes who developed a cardiac device-related endocarditis. The identification of the isolate was performed using phenotypic methods, including mass spectrometry-based methods, and 16S rRNA gene sequencing.

The safety of two Bacillus probiotic strains for human use

Probiotics based on Bacillus strains have been increasingly proposed for prophylactic and therapeutic use against several gastro-intestinal diseases. We studied safety for two Bacillus strains included in a popular East European probiotic. Bacillus subtilis strain that was sensitive to all antibiotics listed by the European Food Safety Authority. Bacillus licheniformis strain was resistant to chloramphenicol and clindamycin. Both were non-hemolytic and did not produce Hbl or Nhe enterotoxins. No bceT and cytK toxin genes were found. Study of acute toxicity in BALB/c mice demonstrated no treatment-related deaths. The oral LD(50) for both strains was more than 2 x 10(11) CFU. Chronic toxicity studies were performed on mice, rabbits, and pigs and showed no signs of toxicity or histological changes in either organs or tissues. We demonstrated that while certain risks may exist for the B. licheniformis strain considering antibiotic resistance, B. subtilis strain may be considered as non-pathogenic and safe for human consumption.

Enterococcal-type glycopeptide resistance genes in non-enterococcal organisms

Although the emergence of vancomycin-resistant enterococci can be attributed, in part, to the increasing use of vancomycin in clinical practice, and glycopeptide use in animal husbandry, the origins of the enterococcal vancomycin resistance genes are not clear. The vancomycin resistance-associated genes in Enterococcus gallinarum, Enterococcus casseliflavus/flavescens, Lactobacillus spp., Leuconostoc spp., Pediococcus spp., and Erysipelothrix rhusiopathiae, are not the source of the high-level vancomycin resistance-associated genes in enterococci. There are, however, environmental organisms which have been found to have gene clusters homologous to the enterococcal vanA, vanB and vanC gene clusters; these include the biopesticide Paenibacillus popilliae, and, to a lesser extent, the glycopeptide-producing organisms Amycolatopsis orientalis and Streptomyces toyocaensis. Still, the exact sources of the enterococcal vancomycin resistance genes remain a mystery.