Bacteremia caused by Desulfovibrio desulfuricans with the intestinal tract as the portal of entry: two case reports and a literature review.

BACKGROUND: Desulfovibrio desulfuricans (D. desulfuricans), a commensal anaerobic gram-negative rod endemic to the soil environment and human gastrointestinal tract, rarely causes bloodstream infections. We report two rare cases of bacteremia caused by D. desulfuricans in which the intestinal tract was the portal of entry. In addition, we summarize findings on D. desulfuricans. CASE PRESENTATION: Case 1: A 51-year-old man presented to the emergency department with the chief complaints of fever and right lower abdominal pain. He was admitted to the hospital with ascending colonic diverticulitis and received empirical antibacterial therapy with piperacillin/tazobactam. Blood culture revealed D. desulfuricans. The patient was discharged after 2 weeks of antimicrobial therapy. Case 2: A 95-year-old woman presented to our hospital with a chief complaint of fever. Owing to an elevated inflammatory response and pyuria, the patient was diagnosed with pyelonephritis and treated with ceftriaxone. Klebsiella pneumoniae was detected in her urine culture, while D. desulfuricans was detected in her blood culture. The patient was then treated with ampicillin/sulbactam for 14 days. The fecal occult blood test result was positive, suggesting a colonic mucosal lesion, such as a malignant tumor, may have been the portal of entry for D. desulfuricans bacteremia. Previous literature reviews indicate that D. desulfuricans bacteremia often results from liver or renal abscesses, intestinal lesions, among others, serving as the portal of entry. Although no specific underlying disease has been reported, it is more common in the older population. We encountered two cases of D. desulfuricans bacteremia and combined them with 15 cases from previous studies to explore the characteristics of the disease. The proportion of patients aged [Formula: see text]60 years was 73.7%; overall, 73.7% had gastrointestinal complications, and 63.2% had abdominal symptoms at the time of presentation. CONCLUSIONS: We encountered two rare cases of D. desulfurican bacteremia. This type of bacteremia is more common in elderly people over 60 years of age and is often associated with hepatobiliary and gastrointestinal diseases.

Septic arthritis caused by Desulfovibrio desulfuricans: A case report and review of the literature.

Septic arthritis can occur by hematogenous seeding, direct joint inoculation, or extension of a bone infection into the joint. We report a case of septic arthritis of the hip caused by Desulfovibrio desulfuricans, an anaerobic sulfur-reducing bacteria. The patient underwent debridement followed by targeted antibiotic therapy with infection resolution.

Assessment of the tolerance to Fe, Cu and Zn of a sulfidogenic sludge generated from hydrothermal vents sediments as a basis for its application on metals precipitation.

A paramour factor limiting metal-microorganism interaction is the metal ion concentration, and the metal precipitation efficiency driven by microorganisms is sensitive to metal ion concentration. The aim of the work was to determine the tolerance of the sulfidogenic sludge generated from hydrothermal vent sediments at microcosms level to different concentrations of Fe, Cu and Zn and the effect on the microbial community. In this study the chemical oxygen demand (COD) removal, sulfate-reducing activity (SRA) determination, inhibition effect through the determination of IC50, and the characterization of the bacterial community´s diversity were conducted. The IC50 on SRA was 34 and 81 mg/L for Zn and Cu, respectively. The highest sulfide concentration (H2S mg/L) and % of sulfate reduction obtained were: 511.30 ± 0.75 and 35.34 ± 0.51 for 50 mg/L of Fe, 482.48 ± 6.40 and 33.35 ± 0.44 for 10 mg/L of Cu, 442.26 ± 17.1 and 30.57 ± 1.18 for 10 mg/L of Zn, respectively. The COD removal rates were of 71.81 ± 7.6, 53.92 ± 1.07 and 57.68 ± 10.2 mg COD/ L d for Fe (50 mg/L), Cu (40 mg/L) and Zn (20 mg/L), respectively. Proteobacteria, Firmicutes, Chloroflexi and Actinobacteria were common phyla to four microcosms (stabilized sulfidogenic and added with Fe, Cu or Zn). The dsrA genes of Desulfotomaculum acetoxidans, Desulfotomaculum gibsoniae and Desulfovibrio desulfuricans were expressed in the microcosms supporting the SRA results. The consortia could be explored for ex-situ bioremediation purposes in the presence of the metals tested in this work.

Adenosine-5'-Phosphosulfate- and Sulfite Reductases Activities of Sulfate-Reducing Bacteria from Various Environments.

A comparative study of the kinetic characteristics (specific activity, initial and maximum rate, and affinity for substrates) of key enzymes of assimilatory sulfate reduction (APS reductase and dissimilatory sulfite reductase) in cell-free extracts of sulphate-reducing bacteria (SRB) from various biotopes was performed. The material for the study represented different strains of SRB from various ecotopes. Microbiological (isolation and cultivation), biochemical (free cell extract preparation) and chemical (enzyme activity determination) methods served in defining kinetic characteristics of SRB enzymes. The determined affinity data for substrates (i.e., sulfite) were 10 times higher for SRB strains isolated from environmental (soil) ecotopes than for strains from the human intestine. The maximum rate of APS reductase reached 0.282-0.862 µmol/min×mg-1 of protein that is only 10 to 28% higher than similar initial values. The maximum rate of sulfite reductase for corrosive relevant collection strains and SRB strains isolated from heating systems were increased by 3 to 10 times. A completely different picture was found for the intestinal SRB Vmax in the strains Desulfovibrio piger Vib-7 (0.67 µmol/min × mg-1 protein) and Desulfomicrobium orale Rod-9 (0.45 µmol/min × mg-1 protein). The determinant in the cluster distribution of SRB strains is the activity of the terminal enzyme of dissimilatory sulfate reduction-sulfite reductase, but not APS reductase. The data obtained from the activity of sulfate reduction enzymes indicated the adaptive plasticity of SRB strains that is manifested in the change in enzymatic activity.

Desulfovibrio desulfuricans bacteremia: A case report and literature review.

Desulfovibrio spp. are sulfate-reducing, anaerobic bacteria that are ubiquitously found in the environment. These organisms infrequently cause human infections, and the clinical characteristics of infection with Desulfovibrio spp. remain unclear. Here, we describe a case of Desulfovibrio desulfuricans bacteremia in an 88-year-old Japanese man with a past medical history of thoracic endovascular aortic repair (TEVAR). His chief complaint was hemoptysis for 2 weeks. A chest contrast-enhanced computed tomography demonstrated an enlarged thoracic aortic aneurysm surrounded by a ring-enhanced lesion, recognized as mediastinal abscess. Gram-negative spiral bacilli were detected in anaerobic blood culture. These bacteria could not be identified using conventional methods, but by analyzing a full base sequence of 16S rDNA, they were identified as D. desulfuricans subsp. desulfuricans. The patient underwent an emergent re-TEVAR, and the infection subsided after being treated with tazobactam/piperacillin and clindamycin, followed by metronidazole. A literature review of previous cases of D. desulfuricans bacteremia suggested that the pathogen was derived from bacterial translocation from the intestine in most cases. Desulfovibrio infection is presumably underestimated due to its infrequency, indolent growth, and difficulty in identification. Desulfovibrio spp. should be suspected when spiral rods are observed in anaerobic culture, and molecular analysis is required for accurate species-level differentiation of the pathogens. To better understand the pathogenicity of these fastidious organisms, further cases based on the exact bacterial identification should be investigated.

A case of liver abscess co-infected with Desulfovibrio desulfuricans and Escherichia coli and review of the literature.

A 73-year-old woman was admitted with consciousness disturbance following a fever. Abdominal computed tomography revealed a large liver abscess with which the presence of Desulfovibrio desulfuricans and Escherichia coli was confirmed by thorough blood and abscess content culture. Empiric meropenem treatment was switched to cefoperazone/sulbactam, followed by ampicillin/sulbactam based on susceptibility testing. Desulfovibrio desulfuricans is a common bacterium that rarely causes liver abscess and may be overlooked during co-infection due to overgrowth of the accompanying bacteria. Clinicians should bear Desulfovibrio desulfuricans in mind and select the appropriate antibiotics according to susceptibility testing when anaerobic bacteria are detected in a liver abscess.

Anaerobiospirillum succiniciproducens y Desulfovibrio desulfuricans en 2 casos de bacteriemias insidiosas / Anaerobiospirillum succiniciproducens and Desulfovibrio desulfuricans in 2 cases of insidious bacteremia

Se presentan 2 casos de bacteriemias insidiosas por bacilos gram negativos anaerobios curvos, espiralados, móviles e infrecuentes en pacientes atendidos en un hospital de la ciudad de Buenos Aires. Estas bacteriemias, asociadas al aislamiento de Anaerobiospirillum y Desulfovibrio, fueron de origen poco claro y afectaron a pacientes inmunocomprometidos, con patologías simultáneas. Pruebas claves en la identificación del género Anaerobiospirillum fueron el estudio de la micromorfología, su carácter de anaerobio estricto, el resultado negativo en la prueba de catalasa, el patrón de discos de interés taxonómico, la fermentación de glucosa y la producción de β-N-acetilglucosaminidasa. El género Desulfovibrio se diferenció por el perfil presentado en las pruebas con discos, por ser asacarolítico, sin actividad de enzimas glucosídicas, y por producir desulfoviridina y H2S. Se alerta sobre la resistencia o sensibilidad intermedia de Anaerobiospirillum succiniciproducens (especie a la que correspondió el aislado de Anaerobiospirillum) a algunos de los antimicrobianos de primera línea frente a bacilos gram negativos anaerobios, como el metronidazol; fueron activas las combinaciones de aminopenicilinas con inhibidores de β-lactamasas y el imipenem. Desulfovibrio desulfuricans (especie a la que correspondió el aislado de Desulfovibrio) fue productora de β-lactamasas y resistente a las cefalosporinas; en cambio, fueron activos el metronidazol, el imipenem y la levofloxacina. La identificación confiable de estos microorganismos orienta hacia el mejor esquema terapéutico.

Two cases of insidious bacteremia by uncommon curve and spiral-shaped, motile anaerobic gram-negative rods are presented. Both of them were of an unclear origin and occurred in immunosuppressed patients with simultaneous diseases. The key tests for the identification of Anaerobiospirillum were its micromorphology, a strictly anaerobic condition, negative catalase activity, the special-potency disk profile, glucose fermentation, and β-NAG production. Desulfovibrio species was identified by all the above preliminary tests but with a different disk profile, as well as for being asaccharolytic and desulfoviridin and H2S producer. We here alert about the resistance or intermediate susceptibility of Anaerobiospirillum succiniciproducens against antimicrobial agents, such as metronidazole, one of the first-line drugs used for the treatment of anaerobic gram-negative infections. Aminopenicillins with β-lactamase-inhibitor combinations and imipenem were active for this agent. Desulfovibrio desulfuricans was β-lactamase producer and resistant to cephalosporins, while metronidazole, imipenem and levofloxacin were active. A reliable identification of these microorganisms is important for establishing the best therapeutic scheme.

[Anaerobiospirillum succiniciproducens and Desulfovibrio desulfuricans in 2 cases of insidious bacteremia]. / Anaerobiospirillum succiniciproducens y Desulfovibrio desulfuricans en 2 casos de bacteriemias insidiosas.

Two cases of insidious bacteremia by uncommon curve and spiral-shaped, motile anaerobic gram-negative rods are presented. Both of them were of an unclear origin and occurred in immunosuppressed patients with simultaneous diseases. The key tests for the identification of Anaerobiospirillum were its micromorphology, a strictly anaerobic condition, negative catalase activity, the special-potency disk profile, glucose fermentation, and ß-NAG production. Desulfovibrio species was identified by all the above preliminary tests but with a different disk profile, as well as for being asaccharolytic and desulfoviridin and H2S producer. We here alert about the resistance or intermediate susceptibility of Anaerobiospirillum succiniciproducens against antimicrobial agents, such as metronidazole, one of the first-line drugs used for the treatment of anaerobic gram-negative infections. Aminopenicillins with ß-lactamase-inhibitor combinations and imipenem were active for this agent. Desulfovibrio desulfuricans was ß-lactamase producer and resistant to cephalosporins, while metronidazole, imipenem and levofloxacin were active. A reliable identification of these microorganisms is important for establishing the best therapeutic scheme.

First report of human infection by Christensenella minuta, a gram-negative, strickly anaerobic rod that inhabits the human intestine.

Christensenella minuta is a Gram-negative strictly anaerobic short rod that inhabits the human gut. This bacterium was isolated in a mixed infection with Desulfovibrio desulfuricansfrom the blood of a patient with a diagnosis of acute appendicitis. The strain was identified by 16S rRNA sequence analysis. As far as we know, this is the first time C.minuta has been isolated from a human clinical specimen.

Desulfovibrio desulfuricans isolates from the gut of a single individual: structural and biological lipid A characterization.

The levels of sulfate-reducing bacteria (SRB), including Desulfovibrionaceae, in the gut increase following a fat-enriched diet. Endotoxins from gut microbiota contribute to the inflammation process, leading to metabolic diseases. Thus, we sought to characterize the lipid A structures of Desulfovibrionaceae lipopolysaccharides (LPS) that are associated with the microbiota inflammatory properties. LPS variants were obtained from two SRB isolates from the gut of a single individual. These LPS variants shared similar lipid A moieties with Enterobacterial LPS, but differed from one another with regard to fatty-acid numbers and endotoxic activity. This first complete structural characterization of Desulfovibrio lipid A gives new insights into previously published data on Desulfovibrio lipid A biosynthesis. LPS microdiversity within SRBs illustrates how adaptation can influence pro-inflammatory potential.

Desulfovibrio desulfuricans bacteremia in a patient hospitalized with acute cerebral infarction: case report and review.

Desulfovibrio spp. can be found in soil, water, and sewage, as well as in the digestive tracts of animals and humans. We report a case of Desulfovibrio desulfuricans bacteremia during hospitalization with acute cerebral infarction following aspiration bronchopneumonia and severe diarrhea, and the case strongly suggests that Desulfovibrio spp. bacteremia can occur as an infection due to disturbance of endogenous gut flora including antibiotic administration. Because Desulfovibrio spp. is difficult to detect in short-time incubation, its bacteremia is possibly overlooked in hospitalized patients. A few clinical cases of D. desulfuricans bacteremia have been reported in Japan, and they are reviewed briefly in this article.

Hydrogenase activity of mineral-associated and suspended populations of Desulfovibrio desulfuricans Essex 6.

The interactions between sulfate-reducing microorganisms and iron oxides influence a number of important redox-sensitive biogeochemical processes including the formation of iron sulfides. Enzymes, such as hydrogenase which catalyze the reversible oxidation of molecular hydrogen, are known to mediate electron transfer to metals and may contribute to the formation and speciation of ferrous sulfides formed at the cell-mineral interface. In the present study, we compared the whole cell hydrogenase activity of Desulfovibrio desulfuricans strain Essex 6 growing as biofilms on hematite (hematite-associated) or as suspended populations using different metabolic pathways. Hematite-associated cells exhibited significantly greater hydrogenase activity than suspended populations during sulfate respiration but not during pyruvate fermentation. The enhanced activity of the hematite-associated, sulfate-grown cells appears to be dependent on iron availability rather than a general response to surface attachment since the activity of glass-associated cells did not differ from that of suspended populations. Hydrogenase activity of pyruvate-fermenting cells was stimulated by addition of iron as soluble Fe(II)Cl2 and, in the absence of added iron, both sulfate-reducing and pyruvate-fermenting cells displayed similar rates of hydrogenase activity. These data suggest that iron exerts a stronger influence on whole cell hydrogenase activity than either metabolic pathway or mode of growth. The location of hydrogenase to the cell envelope and the enhanced activity at the hematite surface in sulfate-reducing cells may influence the redox conditions that control the species of iron sulfides on the mineral surface.

Suitability of fluorescence measurements to quantify sulfate-reducing bacteria.

Fluorescence activity has been used to identify Desulfovibrio and has been termed the 'desulfoviridin test'. This fluorescence is attributed to the prosthetic group of bisulfite reductase, a key enzyme in dissimilatory sulfate reduction. We have pursued the use of fluorescence measurements to quantify sulfate-reducing bacteria. Cells of D. desulfuricans and D. gigas were treated with NaOH and produced two fluorescence spectra: one with maximum fluorescence with an excitation at 395 nm and an emission at 605 nm and another with an excitation at 320 nm and emission at 360 nm. Using the fluorescence with excitation at 395 nm and emission at 605 nm, we explored a series of parameters to measure Desulfovibrio in pure cultures and environmental samples. Fluorescence measurements are reliable provided the cells are treated with 1.75 N NaOH and the chromophore released from the cells is not exposed to strong light intensity, and is not exposed to temperatures greater than 20 °C, and measurements are done within a few minutes of extraction. Bleaching of fluorescence was attributed to metal ions in solution which was not observed until metal concentrations reached 1.5mM. We propose that D. desulfuricans is appropriate as the reference organism for measurement of sulfate-reducing bacteria by fluorescence and by using fluorescence intensity, 10(5) cells/ml can be readily detected in environmental samples.

Desulfovibrio desulfuricans bacteremia in an immunocompromised host with a liver graft and ulcerative colitis.

Desulfovibrio spp. are anaerobic, sulfate-reducing, nonfermenting, Gram-negative bacteria found in the digestive tract of humans. Identification of these species with conventional methods is difficult. The reported case of a Desulfovibrio desulfuricans bacteremia occurring in an immunocompromised host with ulcerative colitis confirms that this organism may be a possible opportunistic human pathogen.

[A case of Desulfovibrio desulfuricans cultured from blood in Japan].

We report a case of Desulfovibrio desulfuricans bacteremia in a 60-year-old-man. In our case, anaerobic blood culture bottle turned out positive after five days' incubation. Gram stain showed the presence of slightly-curved Gram negative rod. Suspecting Campylobacter and Helicobacter, we added microaerobic culture while tentatively reporting Campylobacter to the physician. We then added anaerobic culturing with Brucella HK (RS) Agar because microaerobic culture proved the absence of microaerophile. We found small colonies on the third day, then we started anaerobic culture and eventually identified Desulfovibrio desulfuricans. We believe this is the first report of Desulfovibrio desulfuricans cultured from blood in Japan. In case Gram stain shows the presence of spiral bacterium, it is recommended to observe closely considering Desulfovibrio.

Sulfate-reducing bacterium Desulfovibrio desulfuricans ND132 as a model for understanding bacterial mercury methylation.

We propose the use of Desulfovibrio desulfuricans ND132 as a model species for understanding the mechanism of microbial Hg methylation. Strain ND132 is an anaerobic dissimilatory sulfate-reducing bacterium (DSRB), isolated from estuarine mid-Chesapeake Bay sediments. It was chosen for study because of its exceptionally high rates of Hg methylation in culture and its metabolic similarity to the lost strain D. desulfuricans LS, the only organism for which methylation pathways have been partially defined. Strain ND132 is an incomplete oxidizer of short-chain fatty acids. It is capable of respiratory growth using fumarate as an electron acceptor, supporting growth without sulfide production. We used enriched stable Hg isotopes to show that ND132 simultaneously produces and degrades methylmercury (MeHg) during growth but does not produce elemental Hg. MeHg produced by cells is mainly excreted, and no MeHg is produced in spent medium. Mass balances for Hg and MeHg during the growth of cultures, including the distribution between filterable and particulate phases, illustrate how medium chemistry and growth phase dramatically affect Hg solubility and availability for methylation. The available information on Hg methylation among strains in the genus Desulfovibrio is summarized, and we present methylation rates for several previously untested species. About 50% of Desulfovibrio strains tested to date have the ability to produce MeHg. Importantly, the ability to produce MeHg is constitutive and does not confer Hg resistance. A 16S rRNA-based alignment of the genus Desulfovibrio allows the very preliminary assessment that there may be some evolutionary basis for the ability to produce MeHg within this genus.

Genome sequence of the mercury-methylating strain Desulfovibrio desulfuricans ND132.

Desulfovibrio desulfuricans strain ND132 is an anaerobic sulfate-reducing bacterium (SRB) capable of producing methylmercury (MeHg), a potent human neurotoxin. The mechanism of methylation by this and other organisms is unknown. We present the 3.8-Mb genome sequence to provide further insight into microbial mercury methylation.

Polymicrobial bloodstream infection with Eggerthella lenta and Desulfovibrio desulfuricans.

The advancement in culture identification methods has made possible the culture and identification of slow-growing anaerobic bacteria in clinical samples. Here, we describe a case of polymicrobial bloodstream infection (BSI) caused by Eggerthella lenta and Desulfovibrio desulfuricans, identified by API 20A and Vitek 2 systems and by 16S rRNA sequencing.

Sulfate-reducing bacteria are common members of bacterial communities in Altamira Cave (Spain).

The conservation of paleolithic paintings such as those in Altamira Cave (Spain) is a primary objective. Recent molecular studies have shown the existence of unknown microbial communities in this cave including anaerobic microorganisms on cave walls. Herein, we analyzed an anaerobic microbial group, the sulfate-reducing bacteria (SRB), from Altamira Cave with potential negative effects on painting conservation. In the present work, the communities of bacteria and SRB were studied through PCR-DGGE analysis. Data suggest that SRB communities represent a significant, highly diverse bacterial group in Altamira Cave. These findings represent a first report on this physiological group on caves with paleolithic paintings and their potential biodegradation consequences. Expanding our knowledge on microbial communities in Altamira Cave is a priority to design appropriate conservation strategies.