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delta-(D -alpha-Aminoadipoyl)-cleaving amidase of Ochrobactrum anthropi.

Ochrobactrum anthropi cleaved the delta-(D-alpha-aminoadipoyl)-side chain from delta-(D-alpha-aminoadipoyl)-7-amino-4-methylcoumarin, a beta-lactamase-resistant cephalosporin C analogue. In whole cell conversions up to 1 nkat g(-1) dry cell wt were achieved. O. anthropi possesses also gamma-D-glutamyltranspeptidase activity, 8 nkat g(-1) dry cell wt, the likely cause of delta-(D-alpha-aminoadipoyl)-cleavage.

2-Aminoadipic Acid↗

The effects of NaCl and some heavy metals on the denitrification activity of Ochrobactrum anthropi.

Ochrobactrum anthropi is a well-known Gram-negative bacterium, with the ability to degrade atrazine, urea-formaldehyde and chlorophenols. Investigation were made of the nitrate and nitrite reduction capacities of the strain in succinate and glucose media, and the tolerance of its denitrification to NaCl and some heavy metals. Succinate proved to be a better carbon source to drive denitrification by O. anthropi. Batch fermentation studies in anaerobic succinate medium indicated reduction capacities of 85.4 +/- 9.1 and 48.6 +/- 5.2 mgh(-1)g(-1) dry cell for NO(3) (-) and NO(2) (-), respectively. The nitrite accumulation of the cells revealed that O. anthropi is a group C denitrifying bacterium. Its growth in DSM 1 broth containing NaCl up to 40 g l(-1) demonstrates that O. anthropi belongs in the group of moderately halophilic bacteria. Despite the fact that 42.5 g NaCl l(-1) caused 50% growth inhibition in DSM 1 broth, the cells in the stationary phase readily tolerated NaCl concentrations up to 100 g l(-1). Complete denitrification was achieved in test media containing 30 g NaCl l(-1) after 1 week and the nitrate reductase retained its activity up to 100 g NaCl l(-1). The cells were tolerant to Hg, Zn, Pb, Cu and Ni, and N(2) was producted at tolerated concentrations of the metal in the cases of Hg and Pb.

Culture Media↗

Molecular characterization of chromosomal class C beta-lactamase and its regulatory gene in Ochrobactrum anthropi.

Ochrobactrum anthropi, formerly known as CDC group Vd, is an oxidase-producing, gram-negative, obligately aerobic, non-lactose-fermenting bacillus of low virulence that occasionally causes human infections. It is highly resistant to all beta-lactams except imipenem. A clinical isolate, SLO74, and six reference strains were tested. MICs of penicillins, aztreonam, and most cephalosporins tested, including cefotaxime and ceftazidime, were >128 microg/ml and of cefepime were 64 to >128 microg/ml. Clavulanic acid was ineffective and tazobactam had a weak effect in association with piperacillin. Two genes, ampR and ampC, were cloned by inserting restriction fragments of genomic DNA from the clinical strain O. anthropi SLO74 into pBK-CMV to give the recombinant plasmid pBK-OA1. The pattern of resistance to beta-lactams of this clone was similar to that of the parental strain, except for its resistance to cefepime (MIC, 0.5 ,micro/ml). The deduced amino acid sequence of the AmpC beta-lactamase (pI, 8.9) was only 41 to 52% identical to the sequence of other chromosomally encoded and plasmid-encoded class C beta-lactamases. The kinetic properties of this beta-lactamase were typical for this class of beta-lactamases. Upstream from the ampC gene, the ampR gene encodes a protein with a sequence that is 46 to 62% identical to those of other AmpR proteins and with an amino-terminal DNA-binding domain typical of transcriptional activators of the Lys-R family. The deduced amino acid sequences of the ampC genes of the six reference strains were 96 to 99% identical to the sequence of the clinical strain. The beta-lactamase characterized from strain SLO74 was named OCH-1 (gene, bla(OCH-I)).

Amino Acid Sequence↗

Pyogenic infections due to Ochrobactrum anthropi.

Ochrobactrum anthropi is a nonfermentative gram-negative bacillus that has been isolated with increasing frequency from human clinical specimens. Previously, its pathogenic niche was believed to involve the causation of catheter-associated bacteremic illnesses. We describe three cases of pyogenic infection due to O. anthropi, thereby expanding the known pathogenic potential of this organism.

Adult↗

Ochrobactrum anthropi bacteremia.

Ochrobactrum Anthropi (O. anthropi ), formerly known as Achromobacter CDC group Vd, is a gram-negative bacillus that is aerobic, oxidase producing, and nonlactose fermenting. This organism has been found in environmental and hospital water sources and has pathogenic potential in humans. Most reports in the literature of O. anthropi bacteremia are associated with intravenous line infections. We describe a case of bacteremia with O. anthropi in a 33-month-old boy with acute osteomyelitis. O. anthropi bacteremia also has been reported in immunocompromised hosts. Rarely, O. anthropi has been a cause of soft tissue or bone infection.

Alcaligenes↗

Clinical and microbiologic characteristics of Ochrobactrum anthropi bacteremia.

Ochrobactrum anthropi is an oxidase-positive, nonfermenting, gram-negative bacillus that is an emerging pathogen in immunocompromised patients, particularly in those with indwelling central venous catheters. Reports of clinical manifestation of O. anthropi bacteremia are rare. Herein, we report the clinical and microbiologic characteristics of O. anthropi bacteremia in 15 patients. There were eight males and seven females, whose ages ranged from 1 month to 84 years (mean, 34 years). Ten infections were community acquired. All patients had severe underlying disease and manifested primary O. anthropi bacteremia with no obvious focus. Only three patients had central venous catheters in place at the onset of bacteremia, but none of these showed evidence of catheter-related infection. The mean duration of fever was 4 days (range 0-11) and the mean white blood cell count was 13 x 10(9)/L (range 5.5-28 x 10(9)). All O. anthropi isolates tested were resistant to ampicillin, cephalothin, cefonicid, amoxicillin/clavulanic acid, piperacillin, aztreonam, and ceftazidime, and all were susceptible to gentamicin, amikacin, imipenem, ceftriaxone, and cefoperazone. Most were also susceptible to cefotaxime and moxalactam. Monotherapy with an aminoglycoside or an appropriate beta-lactam (such as cefotaxime or ceftriaxone) yielded good clinical response. None of the 15 patients died directly from O. anthropi bacteremia. Our findings indicate that O. anthropi is often community acquired and can be pathogenic in critically ill or immunocompromised patients with or without indwelling catheters. Although O. anthropi can produce clinically significant infections, the organism seems to be of relatively low virulence.

Adolescent↗

Evaluation of the relatedness of Brucella spp. and Ochrobactrum anthropi and description of Ochrobactrum intermedium sp. nov., a new species with a closer relationship to Brucella spp.

The relatedness of Brucella spp. and Ochrobactrum anthropi was studied by protein profiling, Western blot, immunoelectrophoresis and 16S rRNA analysis. Whole-cell and soluble proteins of brucellae and O. anthropi showed serological cross-reactivities quantitatively and qualitatively more intense than those existing with similar extracts of Agrobacterium spp. Numerical analysis of Western blot profiles of whole-cell extracts showed that O. anthropi LMG 3301 was closer to Brucella spp. than to O. anthropi LMG 3331T, a result not obtained by protein profiling. These differences were not observed by Western blot with soluble fractions, and immunoelectrophoretic analyses suggested that this was due to destruction of conformational epitopes in Western blot procedures with the subsequent simplification of antigenic profile. Analysis of the 16S rRNA sequences of strains previously used in the species definition confirmed that strain LMG 3301, and also LMG 3306, were closer to the brucellae, and that LMG 3331T was in a separate cluster. The LMG 3301 and the LMG 3331T clusters could also be separated by their different colistin sensitivity and by PCR with 16S rRNA Brucella primers, and both methods showed strains of both clusters among clinical isolates classified as O. anthropi by conventional tests. These results and those of previous DNA-DNA hybridization studies [Holmes, B., Popoff, M., Kiredjian, M. & Kersters, K. (1988). Int J Syst Bacteriol 38, 406-416] show that the LMG 3301 cluster and related clinical isolates should be given a new species status for which the name Ochrobactrum intermedium sp. nov. is proposed (type strain is LMG 3301T=NCTC 12171T = CNS 2-75T).

Animals↗

Purification, characterization, and gene cloning of purine nucleosidase from Ochrobactrum anthropi.

A bacterium, Ochrobactrum anthropi, produced a large amount of a nucleosidase when cultivated with purine nucleosides. The nucleosidase was purified to homogeneity. The enzyme has a molecular weight of about 170,000 and consists of four identical subunits. It specifically catalyzes the irreversible N-riboside hydrolysis of purine nucleosides, the K(m) values being 11.8 to 56.3 microM. The optimal activity temperature and pH were 50 degrees C and pH 4.5 to 6.5, respectively. Pyrimidine nucleosides, purine and pyrimidine nucleotides, NAD, NADP, and nicotinamide mononucleotide are not hydrolyzed by the enzyme. The purine nucleoside hydrolyzing activity of the enzyme was inhibited (mixed inhibition) by pyrimidine nucleosides, with K(i) and K(i)' values of 0.455 to 11.2 microM. Metal ion chelators inhibited activity, and the addition of Zn(2+) or Co(2+) restored activity. A 1.5-kb DNA fragment, which contains the open reading frame encoding the nucleosidase, was cloned, sequenced, and expressed in Escherichia coli. The deduced 363-amino-acid sequence including a 22-residue leader peptide is in agreement with the enzyme molecular mass and the amino acid sequences of NH(2)-terminal and internal peptides, and the enzyme is homologous to known nucleosidases from protozoan parasites. The amino acid residues forming the catalytic site and involved in binding with metal ions are well conserved in these nucleosidases.

Amino Acid Sequence↗

Establishment of a gene expression system in Ochrobactrum anthropi.

Genetic studies of Ochrobactrum anthropi are hindered by the lack of a suitable gene expression system. We constructed a set of vectors containing several promoters and a His tag fusion in the N terminus to facilitate protein detection and purification. The new vectors should significantly enhance the genetic manipulation and characterization of O. anthropi.

Gene Expression↗

Infections with the unusual human pathogens Agrobacterium species and Ochrobactrum anthropi.

Agrobacterium species and Ochrobactrum anthropi are generally considered innocuous in clinical settings, yet during the last decade a number of sporadic cases of human infection due to these organisms have been reported. We studied nine cases of infection (septicemia and peritonitis) caused by Agrobacterium-like microorganisms in eight patients. All patients were immunocompromised and had permanent central venous or peritoneal dialysis catheters in place. Seven patients were women, and eight infections were community acquired. Six isolates were identified as Agrobacterium species and three as O. anthropi. These two groups of strains differed in the production of beta-galactosidase and of acid from lactose, erythritol, salicin, and cellobiose. All strains were strictly aerobic, peritrichous, gram-negative bacilli that produced oxidase, urease, and acid from glucose, fructose, arabinose, xylose, mannitol, inositol, and ethanol. The in vitro adherence of isotope-labeled bacteria to silicone tubes was similar to that of staphylococci. We conclude that Agrobacterium species and O. anthropi can be pathogenic in immunocompromised patients with permanent catheters.

Adult↗

Effects of atrazine on Ochrobactrum anthropi membrane fatty acids.

Ochrobactrum anthropi is a gram-negative bacillus recognized as a human opportunist pathogen isolated in clinical specimens and not of clinical significance. We report a new aspect of this bacterium, that it has been isolated from activated sludge. In fact, it is able to grow on atrazine (2-chloro-4-ethylamino-6-isopropyl-amine-s-triazine) by utilizing it as the only source of carbon. Our results show that atrazine (0.03 g/liter) causes a dramatical increase in the degree of saturation of membrane fatty acids. Analysis and identification of bacterial fatty acids were performed by gas chromatography and gas chromatography-mass spectrometry techniques.

Alcaligenes↗

Ochrobactrum anthropi bacteraemia in immunocompetent children.

Ochrobactrum anthropi is an emerging pathogen in immunocompromised patients but infections with the bacterium have very rarely been documented in normal hosts. We report the characteristics of O. anthropi bacteraemia in 11 immunocompetent children, aged 2 months to 7 y, hospitalized in a general hospital during a 5-y period. Children commonly presented with fever, non-specific respiratory or gastrointestinal manifestations, leukocytosis and neutrophilia and had a rapid recovery, even when they did not receive a specific treatment. In 10 cases positive blood cultures were obtained on admission and in all cases subsequent cultures were sterile. In conclusion, O. anthropi may cause bacteraemia in immunocompetent hosts, although further studies are required to clarify whether these isolates represent pseudobacteraemia or whether O. anthropi is a potential pathogen of low virulence.

Anti-Bacterial Agents↗

Characterization, cloning and sequence analysis of the inducible Ochrobactrum anthropi AmpC beta-lactamase.

Ochrobactrum anthropi is resistant to most cephalosporins and penicillins due, at least in part, to the inducible expression of a single beta-lactamase. The beta-lactamase gene has been cloned and sequenced. It encodes an AmpC-type class 1 serine active-site enzyme that hydrolyses mainly cephalosporins and is resistant to inhibition by clavulanic acid. Expression of the ampC gene is inducible via a typical AmpR regulator, which is encoded upstream of ampC. Inducible expression is retained following cloning of O. anthropi ampR-ampC into Escherichia coli, confirming that the signal for AmpR activation in O. anthropi is the same as that used in the Enterobacteriaceae. This is the first reported example of an AmpC beta-lactamase outside of the gamma-subdivision of the bacterial kingdom. Genomic searches of other non-gamma-subdivision bacteria revealed a homologous ampR-ampC cluster in the plant symbiont, Sinorhizobium meliloti.

Amino Acid Sequence↗

Ochrobactrum anthropi bacteremia in pediatric oncology patients.

Ochrobactrum anthropi is an emerging pathogen in immunocompromised hosts, particularly in patients with indwelling catheters. We report the characteristics of 14 O. anthropi bacteremic episodes in 11 children with Hickman-type central catheters. Children presented with fever and nonspecific clinical manifestations. Bacteremia was successfully treated with antibiotics, but catheter removal was necessary to achieve cure in four cases.

Anti-Bacterial Agents↗

Liquid chromatography-electrospray mass spectrometry study of cysteine-10 S-glutathiolation in recombinant glutathione S-transferase of Ochrobactrum anthropi.

Glutathione S-transferase of Ochrobactrum anthropi (OaGST), a bacterium isolated from soils contaminated by xenobiotic pollutants, was recently purified, cloned and characterised in our laboratories. The recombinant OaGST (rOaGST), highly expressed in Escherichia coli, when purified by glutathione-affinity chromatography and then analysed by electrospray ionisation mass spectrometry (ESI-MS), has evidenced a disulphide bond with glutathione (S-glutathiolation), which was removable by reduction with 2-mercaptoethanol. Enzymatic digestion of rOaGST with endoproteinase Glu-C, followed by liquid chromatography (LC)-ESI-MS analyses of the peptide mixtures under both reducing and not reducing conditions, have shown that glutathione was covalently bound to the Cys10 residue of rOaGST. Furthermore, LC-ESI-MS analyses of overexpressed rOaGST in Escherichia coli crude extracts, with and without incubation with glutathione, have not shown any S-glutathiolation of the recombinant enzyme.

Amino Acid Sequence↗

Endogenous Ochrobactrum anthropi endophthalmitis.

PURPOSE: To describe bilateral endogenous endophthalmitis caused by Ochrobactrum anthropi in a partially immunosuppressed patient who had undergone central venous access for hyperalimentation and home intravenous therapy. METHODS: Case report. RESULTS: Blood cultures were positive for O anthropi. Vitreous cultures grew a gram-variable bacillus. The patient's ocular and systemic condition markedly improved after intravitreal antibiotics and systemic ciprofloxacin. CONCLUSIONS: Ochrobactrum anthropi may cause endogenous endophthalmitis in patients with a history of indwelling catheters for venous access or other permanent medical devices.

Aged↗

Infective endocarditis and septic embolization with Ochrobactrum anthropi: case report and review of literature.

Ochrobactrum anthropi, previously known as CDC group Vd, is an aerobic, Gram-negative bacillus of low virulence that occasionally causes human infection. We describe a case of infective endocarditis with O. anthropi complicated by septic embolization. A review of all the literature reported cases of O. anthropi infection is presented and categorized into 'Central line related', 'Transplant related' and "Other pyogenic infections". Mortality appears to be related to the underlying disease state, rather than the organism.

Adult↗

Epidemiological investigation of Ochrobactrum anthropi strains isolated from a haematology unit.

Ochrobactrum anthropi is an oxidase-producing gram-negative bacillus preferring aqueous environments. It is an opportunist of low pathogenicity with a wide and unpredictable antibiotic resistance. We observed bacteraemia caused by this organism in two immunocompromized patients hospitalized in the same haematology unit and catheter-associated sepsis was recognized within two days. Another isolate was obtained from the stools of a third patient of the same unit. Environmental investigations recovered an isolate from a tap-water sample of the unit. Pulsed-field gel electrophoresis analysis of these four isolates and two others isolates previously found in the same ward, showed identical restriction patterns for the two blood isolates and confirmed that the two bacteraemia were epidemiologically related.

Adult↗