Oerskovia xanthineolytica: a new pathogen in bone marrow transplantation

A case report of the differential diagnosis of Cellulosimicrobium cellulans-infected endocarditis combined with intracranial infection by conventional blood culture and second-generation sequencing

Background

Cellulosimicrobium cellulans is a gram-positive filamentous bacterium found primarily in soil and sewage that rarely causes human infection, especially in previously healthy adults, but when it does, it often indicates a poor prognosis.

Case presentation

We report a case of endocarditis and intracranial infection caused by C. cellulans in a 52-year-old woman with normal immune function and no implants in vivo. The patient started with a febrile headache that progressed to impaired consciousness after 20 days, and she finally died after treatment with vancomycin combined with rifampicin. C. cellulans was isolated from her blood cultures for 3 consecutive days after her admission; however, there was only evidence of C. cellulans sequences for two samples in the second-generation sequencing data generated from her peripheral blood, which were ignored by the technicians. No C. cellulans bands were detected in her cerebrospinal fluid by second-generation sequencing.

Conclusions

Second-generation sequencing seems to have limitations for certain specific strains of bacteria.

Cellulosimicrobium cellulans aortic prosthetic valve endocarditis

Introduction.

Invasive infections due to Cellulosimicrobium spp. (a Gram-positive coryneform) are extremely rare. Only a few cases of bloodstream infections and endocarditis have been described, as bacteraemia due to coryneforms is usually discarded as blood culture contamination.

Case presentation.

A 66-year-old female, with a history of aortic valve replacement, presented with fever, left leg purpura and acute kidney injury. Multiple repeated blood cultures were positive for Cellulosimicrobium cellulans, and targeted therapy was started. At first, endocarditis was excluded by echocardiograms, and the acute nephritis was interpreted as an atypical presentation of Henoch–Shönlein purpura. High-dose prednisone was started, and after 10 weeks the patient presented again with fever, mental confusion and acute left arm ischaemia. A subsequent echocardiogram and radiolabelled leukocyte scintigraphic evaluation revealed aortic prosthetic valve endocarditis with periprosthetic abscess and arterial brachial thrombosis. The patient deceased, and the autoptic examination confirmed an aortic valve periprosthetic abscess and revealed multiple arterial thromboses and septic embolisms in the kidneys, brain, spleen and myocardium.

Conclusion.

Isolation of coryneform bacteria on blood culture should not always be discarded as blood culture contamination. In the case of endocarditis due to Cellulosimicrobium spp., the removal of any prosthetic material, along with prolonged in vitro active antimicrobial therapy, should be pursued in order to reduce persistence or relapses of infection.

Infections due to Cellulosimicrobium species: case report and literature review

Background

Cellulosimicrobium species, formely known as Oerskovia species, are gram-positive bacilli belonging to the order Actinomycetales. They rarely cause human infections. The genus comprises two pathogenic species in humans: C. cellulans and C. funkei. Based on a case report, we provide a review of the literature of infections caused by Cellulosimicrobium/Oerskovia, in order to improve our knowledge of this unusual infection.

Case presentation

An 82-year-old woman with aortic prosthetic valve presented to the hospital with fever and heart failure. Further work up revealed the diagnosis of C. cellulans infective endocarditis (IE). The strain was identified by MALDI-TOF MS, API Coryne and 16S rRNA sequencing. The patient was deemed not to be an operative candidate and died despite the antibiotic therapy 35 days after admission.

Conclusions

Reviewing cases of Cellulosimicrobium species infections and communicating the successful and unsuccessful clinical experiences can assist future healthcare providers. Our case and those previously reported indicate that Cellulosimicrobium species usually infect immunocompromised patients or foreign body carriers. The most frequent pattern of infection is central venous catheter related bacteremia. The optimal treatment should include foreign body removal and valve surgery should be considered in case of IE.

Bacteremia caused by cellulosimicrobium in a bone marrow transplant patient: A case report and literature review

Background

Cellulosimicrobium sp. is a ubiquitous gram-positive bacillus that was formerly known as Oerskovia. This bacterium is found in soil and decaying plant material and is rarely associated with infections in humans.

Case report

We report the case of a 44 year-old woman with history of bone marrow transplant that developed Cellulosimicrobium sp. bacteremia secondary to a central line infection. She was admitted with presumed sepsis. Blood cultures from central line and periphery revealed the growth of gram-positive rods that were further identified as Cellulosimicrobium sp. by MALDI-TOF. She was treated with vancomycin and line removal. Microbiologic cure was achieved; however, she developed hospital-acquired pneumonia, which led to a fatal outcome.

Conclusion

To our knowledge, there are only 15 documented cases of Cellulosimicrobium sp. bacteremia. Our case illustrates the potential pathogenicity of this bacterium and the importance of appropriate antimicrobial therapy and removal of infected central catheters. It is essential to know that gram-positive bacilli should not be disregarded as contaminants when recovered from multiple blood cultures. In this situation, a full microbiologic identification must be attempted.

Septic arthritis due to Cellulosimicrobium cellulans

Cellulosimicrobium cellulans has been reported as a rare cause of human pathogenesis. Infections mainly occur in immunocompromised patients and very often are associated with a foreign body. We report the first case of septic arthritis caused by C. cellulans in an immunocompetent patient. Our patient suffered a penetrating palm tree thorn injury to his left knee 8 weeks before admission. Although no foreign objects were found, they were suspected because previous reports suggest a frequent association with this microorganism, and open debridament was performed. Removal of foreign bodies related to this organism must be considered a high-priority treatment in these patients to achieve a complete recovery.

Nocardia cyriacigeorgica: a case of endocarditis with disseminated soft-tissue infection

Nocardia cyriacigeorgica is a common environmental organism. It has been isolated from clinical samples in Europe, Asia and North America, predominantly from respiratory samples but also from samples from several other sites. We present a case report of an 85-year-old female patient in the UK who was found to have a multi-focal soft-tissue infection from which N. cyriacigeorgica was isolated. She had a background history of chronic obstructive pulmonary disease and corticosteroid use for polymyalgia rheumatica. During the course of her treatment echocardiography showed the presence of a mobile heart mass attached to a valve leaflet, a major Dukes criterion for endocarditis. We suggest that in cases of disseminated Nocardia infection, endocarditis should be tested for, particularly in cases failing to respond to treatment. We also review previous reports of both N. cyriacigeorgica infection, and of endocarditis due to Nocardia species and related genera.

Cellular protection by erythropoietin: new therapeutic implications?

Erythropoietin (EPO), the principal hematopoietic hormone produced by the kidney and the liver in fetuses, regulates mammalian erythropoiesis and exhibits diverse cellular effects in nonhematopoietic tissues. The introduction of recombinant human EPO (rhEPO) has marked a significant advance in the management of anemia associated with chronic renal failure. At the same time, experimental studies have unveiled its potential neuroprotective and cardioprotective properties, occurring independently of its hematopoietic action. As with other cytoprotective agents, administration of exogenous rhEPO can confer cerebral and myocardial protection against ischemia-reperfusion injury in terms of reduction in cellular apoptosis and necrosis, as well as improvement in functional recovery. Very recent studies even suggest that this drug could have beneficial applications in oncology, protecting against chemotherapy cardiotoxicity. The purpose of this letter is to review current information regarding the various conditions in which rhEPO and its derivates could confer cellular protection. We also address clinical perspectives and novel therapeutic strategies that could be developed based on these studies. Thus, EPO seems to be a very promising agent for protecting cellular survival during both acute and chronic diseases, and its future should be considered with enthusiasm.

Clearance of Cellulosimicrobium cellulans bacteremia in a child without central venous catheter removal

Cellulosimicrobium cellulans (formerly known as Oerskovia xanthineolytica) rarely causes human infection. Infections have been reported in immunocompromised hosts or in patients with foreign bodies, such as catheters, where treatment has generally involved removal of the foreign body. We report on a case in which the organism was isolated in multiple blood cultures from a 13-year-old male. After initial therapy failed, treatment with vancomycin and rifampin resulted in infection clearance without removal of the central venous catheter.

Cell Death Mechanism and Protective Effect of Erythropoietin after Focal Ischemia in the Whisker-Barrel Cortex of Neonatal Rats

Cell death induced by the combined insult of hypoxia-ischemia in neonatal rodents has been extensively investigated. Ischemia-only-induced cell death, however, has been much less characterized. Based on the notion that 1) ischemic stroke is a relatively common disorder in human neonates, and 2) developing cells are more susceptible to apoptosis, the present study examined whether typical apoptosis was induced by cerebral ischemia in a new neonatal rat model. Erythropoietin (EPO; Epoetin) was tested for its protective effect against ischemia-induced cell death. Postnatal day 7 rats were subjected to permanent occlusion of the middle cerebral artery branch supplying the right whisker-barrel cortex. Terminal deoxynucleotidyl transferase biotin-dUTP nick end-labeled-positive cells in the ischemic region were detectable 4 h after ischemia and reached a peak level 16 h later. The cell death was preceded by caspase activation and cytochrome c release. Cell body shrinkage was evident among damaged cells. Agarose gel electrophoresis showed DNA damage with a smear pattern as well as DNA laddering. Electron microscopy demonstrated apoptotic features such as cell shrinkage, chromatin condensation, and fragmentation; meanwhile, necrotic alterations coexisted in the cytoplasm. EPO treatment increased signal transducers and activators of transcription-5 and Bcl-2 levels, markedly attenuated apoptotic cell death, and reduced ischemic infarct in the cortex. It is suggested that focal ischemia in the developing brain causes cell death with prominent apoptotic features coexisting with some characteristics of necrosis. This is consistent with the concept of hybrid death described previously in cultures and adult or developing brain. EPO may be explored as a potential therapy for neonatal ischemic stroke.

Critical role for Akt1 in the modulation of apoptotic phosphatidylserine exposure and microglial activation

Biological targets for neurodegenerative disease that focus on the intrinsic maintenance of cellular integrity and the extrinsic prevention of phagocytic cellular disposal offer the greatest promise for therapeutic intervention. Protein kinase B (Akt1), a serine-threonine kinase closely involved in cell growth and survival, offers a strong potential to address both intrinsic and extrinsic mechanisms of neuronal injury. We demonstrate that overexpression of a constitutively active form of Akt1 (myristoylated Akt1) in differentiated SH-SY5Y neuronal cells provides intrinsic cellular protection against apoptotic genomic DNA destruction and membrane phosphatidylserine (PS) exposure. Transfection of SH-SY5Y cells with a plasmid encoding a kinase-deficient dominant-negative Akt1 eliminates cytoprotection, suggesting that activation of Akt1 is necessary and sufficient to prevent apoptotic destruction. Apoptotic neuronal membrane PS exposure provides a unique pathway for Akt1 to offer extrinsic cellular protection and block microglial activation, because independent cotreatment with an anti-PS receptor neutralizing antibody could also prevent microglial proliferation. Akt1 maintains nuclear DNA integrity and membrane PS exposure through the specific inhibition of caspase 3-, 8-, and 9-like activities that were linked to mitochondrial membrane potential and cytochrome c release. Our work elucidates a novel capacity for Akt1 to maintain cellular integrity through a series of cysteine protease pathways and to uniquely regulate microglial activation through the modulation of membrane PS residue externalization.