ABSTRACT
Polyphosphate kinase plays an important role in the catalytic synthesis of ATP in vitro. In order to find a polyphosphate kinase that can efficiently synthesize ATP using short-chain polyphosphate (polyP) as substrate, the polyphosphate kinase 2 (PPK2) from Sphingobacterium siyangensis was cloned and expressed in Escherichia coli BL21(DE3). As an enzyme for ATP regeneration, PPK2 was used in combination with l-amino acid ligase (YwfE) to produce l-alanyl-l-glutamine (Ala-Gln). The length of ppk2 of S. siyangensis is 810 bp, encoding 270 amino acids. The SDS-PAGE showed that PPK2 was expressed correctly and its molecular weight was 29.7 kDa as expected. The reaction conditions of PPK2 were optimized. PPK2 could maintain good activity in the range of 22-42 ℃ and pH 7-10. The highest enzyme activity was observed at 37 ℃, pH 7, 30 mmol/L magnesium ion (Mg2+), 5 mmol/L ADP and 10 mmol/L sodium hexametaphosphate, and the yield of ATP reached 60% of the theoretical value in 0.5 hours at this condition. When used in combination with YwfE to produce Ala-Gln, the PPK2 showed a good applicability as an ATP regeneration system, and the effect was similar to that of direct addition of ATP. The PPK2 from S. siyangensis shows good performance in a wide range of temperature and pH, synthesizes ATP with cheap and readily available short chain polyP as substrate. The PPK2 thus provides a new enzyme source for ATP dependent catalytic reaction system.
Subject(s)
Sphingobacterium/metabolism , Phosphotransferases (Phosphate Group Acceptor)/metabolism , Amino Acids , Adenosine Triphosphate , Regeneration , Polyphosphates/metabolismABSTRACT
Resumen Sphingobacterium multivorum es un bacilo gramnegativo no fermentador, que infrecuentemente causa enfermedad en humanos. En la literatura médica existen escasos reportes de infecciones causadas por este microorganismo, en general, en hospederos con alguna comorbilidad. Presentamos el primer caso reportado, según nuestro conocimiento, de una infección de piel y tejidos blandos por Sphingobacterium multivorum en un paciente pediátrico gran quemado.
Abstract Sphingobacterium multivorum is a non-fermentative gram-negative bacillus that rarely causes human infections. In the medical literature, the few reported cases of infections resulting from S. multivorum usually occurred in patients with an associated comorbidity. We present the first case report, according our knowledge, of a skin and soft tissue infection by S. multivorum infection in a pediatric patient after a burn injury.
Subject(s)
Humans , Male , Child , Burns , Gram-Negative Bacterial Infections , SphingobacteriumABSTRACT
Abstract Objective: To report a case septic arthritis with a rare pathogen in a immunosuppressed child. Case description: Male patient, 6 years old, had liver transplant five and half years ago due to biliary atresia. Patient was using tacrolimus 1mg q.12h. This patient started to have pain in left foot and ankle and had one episode of fever 3 days before hospital admission. Physical examination showed weight 17kg, height 109cm, temperature 36.4°C, with pain, swelling and heat in the left ankle, without other clinical signs. Initial tests: hemoglobin 11.7g/dL hematocrit 36.4%, leukocyte count 17,600µL-1 (7% banded neutrophils, 70% segmented neutrophils, 2% eosinophils, basophils 1%, 13% lymphocytes, 7% monocytes) C-reactive protein 170.88mg/L. Joint ultrasound showed moderate effusion in the site. Patient was submitted to surgical procedure and Sphingobacterium multivorum was isolated from the effusion. The germ was susceptible to broad spectrum cephalosporins (ceftriaxone and cefepime) and fluoroquinolones (ciprofloxacin and levofloxacin), and it was resistant to carbapenemic antibiotics and aminoglycosides. He was treated intravenously with oxacillin for 15 days and ceftriaxone for 13 days, and orally with ciprofloxacin for 15 days, with good outcome. Comments: The S. multivorum is a gram negative bacillus that belongs to Flavobacteriaceae family and it is considered non-pathogenic. It has rarely been described as a cause of infections in humans, especially in hospital environment and in immunosuppressed patients. This case report is relevant for its unusual etiology and for the site affected, which may be the first case of septic arthritis described.
Resumo Objetivo: Relatar um caso de artrite séptica de etiologia rara em uma criança imunossuprimida. Descrição do caso: Paciente masculino, seis anos, transplantado hepático havia cinco anos e meio devido à atresia de vias biliares, em uso de tacrolimus 1 mg de 12/12 horas, iniciou dor em pé e tornozelo esquerdo e um episódio de febre três dias antes da internação. Ao exame físico, peso 17kg, estatura 109cm, temperatura de 36,4°C, com dor, edema e calor no tornozelo esquerdo e sem outras alterações. Exames da entrada: hemoglobina 11,7g/dL, hematócrito 36,4%, leucócitos, 17.600/uL (7% bastões, 70% segmentados, 2% eosinófilos, 1% basófilo, 13% linfócitos, 7% monócitos), proteína C reativa 170,88mg/L. Ultrassonografia articular evidenciou moderado derrame no recesso tíbio talar anterior esquerdo. Feita limpeza cirúrgica com o isolamento do S. multivorum na cultura do líquido articular, suscetível a um amplo espectro de cefalosporinas (cefepime e ceftriaxone) e fluoroquinolonas (ciprofloxacino e levofloxacino), esistente a carbapenêmicos e aminoglicosídeos. Tratado com oxacilina por 15 dias e ceftriaxone 13 dias intravenoso e ciprofloxacina via oral por mais 15 dias com boa evolução. Comentários: O Sphingobacterium multivorum é um bacilo gram negativo, pertencente à família Flavobacteriaceae, considerado não patogênico, tem sido raramente descrito como etiologia de infecções em seres humanos principalmente em ambientes hospitalares e em imunossuprimidos. O relato deste caso é relevante por sua etiologia incomum e pelo sítio acometido, pode ser este o primeiro caso de artrite séptica descrito.
Subject(s)
Humans , Male , Child , Arthritis, Infectious/microbiology , Sphingobacterium , Arthritis, Infectious/immunology , Immunocompromised Host , Gram-Negative Bacterial Infections/immunologyABSTRACT
We report a case of fatal meningitis caused by bacteria, Sphingobacterium multivorum, probably first time being reported from India. S. mulivorum has been isolated from various clinical specimens but it is only rarely been associated with serious infections. Sphingobacterium species are generally resistant to aminoglycosides and polymyxin B. Susceptibility to β-lactam antibiotics is variable, requiring testing for individual drug. This 36 year male had two weeks history of high-grade fever with altered sensorium and occasional seizures. Patient admitted with septicemia and subsequently developed meningitis and succumbed to his illness after being discharged against medical advice. His CSF culture yielded S. multivorum subsequently confirmed by mini API, bioMérieux Inc. Marcy-l’Etoile France. Due to its rare association with common clinical conditions, it requires a high degree of suspicion and expertise to prove its presence in clinical specimens. Since this bacterium is inherently resistant to many classes of antibiotics, a vigilant and efficient microbiological work up is needed to establish its diagnosis and prompt treatment.
ABSTRACT
Sphingobacterium spiritivorum has been rarely isolated from clinical specimens of immunocompromised patients, and there have been no case reports of S. spiritivorum infection in Korea to our knowledge. We report a case of S. spiritivorum bacteremia in a 68-yr-old woman, who was diagnosed with acute myeloid leukemia and subsequently received chemotherapy. One day after chemotherapy ended, her body temperature increased to 38.3degrees C. A gram-negative bacillus was isolated in aerobic blood cultures and identified as S. spiritivorum by an automated biochemical system. A 16S rRNA sequencing analysis confirmed that the isolate was S. spiritivorum. The patient received antibiotic therapy for 11 days but died of septic shock. This is the first reported case of human S. spiritivorum infection in Korea. Although human infection is rare, S. spiritivorum can be a fatal opportunistic pathogen in immunocompromised patients.