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PubMed2006

Achromobacter xylosoxidans in cystic fibrosis: prevalence and clinical relevance.

BACKGROUND: Achromobacter xylosoxidans is increasingly cultured in sputum from cystic fibrosis (CF) patients; nevertheless, there are few published data on the clinical impact of this infection or chronic colonisation. METHODS: Relying on DNA fingerprinting techniques we studied the prevalence of A. xylosoxidans in our CF population. In a retrospective case control study the clinical status of patients with at least 3 sputum cultures positive for A. xylosoxidans over at least 9 months, at the moment of the first positive culture and during the period of colonisation were compared to age (+/-1 year), gender and to Pseudomonas aeruginosa colonisation controlled CF patients who had never A. xylosoxidans positive sputum cultures. RESULTS: The prevalence of patients with at least one positive A. xylosoxidans culture was 17.9%. 5.3% of the patients fulfilled the criteria of our definition of colonisation. Colonised patients had a median age of 20 years (range 11-27 years) and a mean colonisation period of 1.5 (+/-0.9) years. At the moment of the first positive culture we found significantly lower Bhalla scores on HRCT scans of the lungs (11+/-3 versus 16+/-3, p<0.002), lower Brasfield chest X-ray scores (14+/-3 versus 18+/-3, p<0.019), lower FVC values (70%+/-22 versus 94%+/-12, p<0.017) and lower FEV(1) values (55%+/-32 versus 78%+/-23, p=0.123), although the latter did not reach significance. There was no significant difference in body mass index (BMI) (18.7+/-3 kg/m2 versus 19.6+/-3 kg/m2, p=0.8). Over the study period A. xylosoxidans-colonised patients did have more need for intravenous antibiotic treatment courses (19 versus 5, p<0.001); nevertheless, there was no significant difference in lung function decline over the study period (FVC: -6.25+/-12.34% versus -5.62+/-8.30%, p 0.77, FEV1: -5.62+/-8.30% versus -1.87+/-11.58%, p<0.47). CONCLUSIONS: The prevalence of A. xylosoxidans infection or colonisation is probably underestimated. Colonised patients are mostly older, with more pronounced lung damage and lower lung function values. Although there was more need for intravenous antibiotic treatment courses, no faster decline in lung function was observed in A. xylosoxidans positive patients.

Achromobacter denitrificans↗
PubMed2006

Bilateral simultaneous Achromobacter xylosoxidans keratitis following penetrating keratoplasty.

We report a case of severe bilateral simultaneous Achromobacter xylosoxidans keratitis following penetrating keratoplasty (PKP) in a patient with graft-versus-host disease. The predisposing factors, clinical features, treatment options, and final visual outcome are reviewed. To our knowledge, this is the first report of bilateral A xylosoxidans keratitis following PKP.

Achromobacter denitrificans↗
PubMed2006

Insight into catalysis of nitrous oxide reductase from high-resolution structures of resting and inhibitor-bound enzyme from Achromobacter cycloclastes.

The difficult chemistry of nitrous oxide (N2O) reduction to gaseous nitrogen (N2) in biology is catalysed by the novel micro4-sulphide-bridged tetranuclear Cuz cluster of the N2O reductases (N2OR). Two spectroscopically distinct forms of this cluster have been identified as CuZ and CuZ*. We have obtained a 1.86 A resolution crystal structure of the pink-purple species of N2OR from Achromobacter cycloclastes (AcN2OR) isolated under aerobic conditions. This structure reveals a previously unobserved ligation with two oxygen atoms from H2O/OH- coordinated to Cu1 and Cu4 of the catalytic centre. We ascribe this structure to be that of the CuZ form of the cluster, since the previously reported structures of two blue species of N2ORs, also isolated aerobically, have characterised the redox inactive CuZ* form, revealing a single water molecule at Cu4. Exposure of the as-isolated AcN2OR to sodium iodide led to reduction of the electron-donating CuA site and the formation of a blue species. Structure determination of this adduct at 1.7 A resolution showed that iodide was bound at the CuZ site bridging the Cu1 and Cu4 ions. This structure represents the first observation of an inhibitor bound to the Cu1-Cu4 edge of the catalytic cluster, providing clear evidence for this being the catalytic edge in N2ORs. These structures, together with the published structural and spectroscopic data, give fresh insight into the mode of substrate binding, reduction and catalysis.

Achromobacter cycloclastes↗
PubMed2003

Cytoplasmic expression of the Achromobacter xylosoxidans blue copper nitrite reductase in Escherichia coli and characterisation of the recombinant protein.

The gene of the Achromobacter xylosoxidans (DSM 2402) blue copper-containing nitrite reductase was amplified using the polymerase chain reaction. DNA sequence analysis reveals that the amino acid sequence is identical to those of the GIFU1051 and the NCIMB11015 A. xylosoxidans nitrite reductases. The gene encoding the mature coding region for DSM 2402 nitrite reductase was cloned into a pET-vector, overexpressed in the cytoplasm of Escherichia coli BL21(DE3), and the expressed holoprotein was purified to apparent homogeneity by cation-exchange chromatography. The recombinant blue copper-containing nitrite reductase was obtained in high yields of 70mgL(-1) of culture. The specific catalytic activity as well as the electronic absorption and electron paramagnetic resonance spectra agree with corresponding data for the native protein. Mass spectroscopic analysis of the recombinant nitrite reductase gave a molecular weight of 36659.1Da for the apo-protein monomer, in agreement with the expected molecular mass based on the amino acid sequence.

Achromobacter denitrificans↗
PubMed2005

Achromobacter xylosoxidans endophthalmitis diagnosed by polymerase chain reaction and gene sequencing.

PURPOSE: To report a patient with Achromobacter xylosoxidansendophthalmitis that was diagnosed using polymerase chain reaction and gene sequencing. METHODS: Case report. A patient with culture-negative endophthalmitis underwent an anterior chamber tap. Polymerase chain reaction was performed on the aqueous sample using the 16S ribosomal DNA primer set to detect and amplify bacterial DNA. The amplified DNA was sequenced and compared to archived sequences in a gene library using the BLAST search program. RESULTS: A 214-base pair gene sequence was amplified and matched with the gene sequence for A. xylosoxidans. Antimicrobial treatment was instituted with resolution of hypopyon, anterior chamber cells, and vitreous cells one month after treatment. CONCLUSIONS: Polymerase chain reaction of 16S rDNA combined with gene sequencing may be an alternative method of diagnosing culture-negative bacterial endophthalmitis.

Achromobacter denitrificans↗
PubMed2004

Cyclo(L-leucyl-L-prolyl) produced by Achromobacter xylosoxidans inhibits aflatoxin production by Aspergillus parasiticus.

Aflatoxins are potent carcinogenic and toxic substances that are produced primarily by Aspergillus flavus and Aspergillus parasiticus. We found that a bacterium remarkably inhibited production of norsolorinic acid, a precursor of aflatoxin, by A. parasiticus. This bacterium was identified as Achromobacter xylosoxidans based on its 16S ribosomal DNA sequence and was designated A. xylosoxidans NFRI-A1. A. xylosoxidans strains commonly showed similar inhibition. The inhibitory substance(s) was excreted into the medium and was stable after heat, acid, or alkaline treatment. Although the bacterium appeared to produce several inhibitory substances, we finally succeeded in purifying a major inhibitory substance from the culture medium using Diaion HP20 column chromatography, thin-layer chromatography, and high-performance liquid chromatography. The purified inhibitory substance was identified as cyclo(L-leucyl-L-prolyl) based on physicochemical methods. The 50% inhibitory concentration for aflatoxin production by A. parasiticus SYS-4 (= NRRL2999) was 0.20 mg ml(-1), as determined by the tip culture method. High concentrations (more than 6.0 mg ml(-1)) of cyclo(L-leucyl-L-prolyl) further inhibited fungal growth. Similar inhibitory activities were observed with cyclo(D-leucyl-D-prolyl) and cyclo(L-valyl-L-prolyl), whereas cyclo(D-prolyl-L-leucyl) and cyclo(L-prolyl-D-leucyl) showed weaker activities. Reverse transcription-PCR analyses showed that cyclo(L-leucyl-L-prolyl) repressed transcription of the aflatoxin-related genes aflR, hexB, pksL1, and dmtA. This is the first report of a cyclodipeptide that affects aflatoxin production.

Achromobacter denitrificans↗
PubMed2004

Cloning, overexpression, and characterization of a novel thermostable penicillin G acylase from Achromobacter xylosoxidans: probing the molecular basis for its high thermostability.

The gene encoding a novel penicillin G acylase (PGA), designated pgaW, was cloned from Achromobacter xylosoxidans and overexpressed in Escherichia coli. The pgaW gene contains an open reading frame of 2586 nucleotides. The deduced protein sequence encoded by pgaW has about 50% amino acid identity to several well-characterized PGAs, including those of Providencia rettgeri, Kluyvera cryocrescens, and Escherichia coli. Biochemical studies showed that the optimal temperature for this novel PGA (PGA650) activity is greater than 60 degrees C and its half-life of inactivation at 55 degrees C is four times longer than that of another previously reported thermostable PGA from Alcaligenes faecalis (R. M. D. Verhaert, A. M. Riemens, J. V. R. Laan, J. V. Duin, and W. J. Quax, Appl. Environ. Microbiol. 63:3412-3418, 1997). To our knowledge, this is the most thermostable PGA ever characterized. To explore the molecular basis of the higher thermostability of PGA650, homology structural modeling and amino acid composition analyses were performed. The results suggested that the increased number of buried ion pair networks, lower N and Q contents, excessive arginine residues, and remarkably high content of proline residues in the structure of PGA650 could contribute to its high thermostability. The unique characteristic of higher thermostability of this novel PGA provides some advantages for its potential application in industry.

Achromobacter denitrificans↗
PubMed2005

Shared genotypes of Achromobacter xylosoxidans strains isolated from patients at a cystic fibrosis rehabilitation center.

During a study examining transmission of Pseudomonas aeruginosa among 76 cystic fibrosis patients in a rehabilitation center, where patients stay in close contact during prolonged periods, several clusters of patients carrying genotypically identical P. aeruginosa, as well as two clusters of 4 and 10 patients, respectively, colonized with genotypically identical Achromobacter xylosoxidans strains, were discovered.

Achromobacter denitrificans↗
PubMed1961

Four cases of human infection with Achromobacter anitratus.

Four cases of human infection with Achromobacter anitratus, one of which was fatal, are described. They all occurred at one hospital within a period of two months. The bacteriology, antibiotic sensitivity, and pathogenicity of the organisms are discussed. One of the strains was found to differ from the other three.

Achromobacter↗
PubMed2005

Characteristics of Achromobacter xylosoxidans bacteremia in northern Taiwan.

There were 40 cases of Achromobacter xylosoxidans bacteremia during a 6-year period in a medical center in northern Taiwan. Males outnumbered females (72.5% vs 27.5%). Common underlying diseases and conditions in these 40 bacteremic patients were malignancies (57.5%), central venous catheter implants (55%), surgery (35%), neutropenia (30%) and use of steroids (25%). Recurrent bacteremia occurred in 4 patients (10%), all of whom had a central venous catheter implant which was considered the most probable source of infection. More than one-quarter (27.5%) of the cases were community acquired. The mortality rate due to A. xylosoxidans bacteremia was 47.5%. Risk factors significantly associated with mortality were nosocomial acquisition and polymicrobial bacteremia. Disk susceptibility testing showed that these isolates were resistant to aminoglycosides and most cephalosporins but were susceptible to piperacillin, imipenem, ceftazidime and trimethoprim-sulfamethoxazole.

Achromobacter denitrificans↗
PubMed2005

Degradation of natural rubber by Achromobacter sp. NRB and evaluation of culture conditions.

A natural rubber degrading candidate was isolated from a soil sample from Aswan, Egypt. The strain was able to grow on natural rubber as a sole source for carbon and energy. According to its degradation behavior, it grew adhesively and in direct contact with the rubber substrate and led to disintegration of the material during cultivation. Furthermore, this strain was not able to form a clear zone (translucent halos) around bacterial colonies after cultivation on NR latex plates. Taxonomic analysis of the strain based on partial 16S rRNA similarity examinations indicated that bacterial candidate belongs to genus Achromobacter sp. Schiff's reagent staining tests performed during cultivation of the strain on NR latex gloves of different sizes, treated or nontreated, revealed that the strain was able to colonize the rubber surface. Formation of bacterial films and occurrence of compounds containing aldehyde groups during cultivation was observed. The tested strain showed a higher colonization efficiency on small or treated pieces of NR latex gloves, while a lower colonization efficiency was recognized when grown on large or nontreated NR latex gloves. Plackett-Burman experimental design, based on numerical modeling, was applied to evaluate the significance of culture conditions affecting natural rubber degradation by the bacterial candidate. Eleven variables through fourteen trials were studied simultaneously. Based on rubber mineralization data, the highest positive variables affecting rubber degradation were NR granules, K2HPO4, Na-succinate and NH4Cl, while MgSO4 x 7H2O and KH2PO4 were the lowest significant variables.

Achromobacter↗
PubMed1987

Resistance to biological and chemical challenge in rodents treated with xerosin II, a natural product of Achromobacter xerosis.

The biological response-modifying activity of acid-precipitable material from Achromobacter xerosis was first described as suppression of viral pneumonia in mice. Later, this acid-precipitable material (xerosin) was found to have antiinflammatory activity and to induce tumor regression in chickens infected with Rous sarcoma virus. Here, we report further purification of xerosin resulting in a product (xerosin II) that retains high biological activity against viral and endotoxin-induced pneumonia in mice. In addition, we describe new activities of xerosin II in two rat tumor systems. Female CD rats received gastric intubations of 7,12-dimethylbenz(a)anthracene; 2 weeks later, half began 4 weeks of treatment with xerosin II, while others received saline only. Xerosin II treatment significantly delayed the appearance of the first palpable mammary tumors per rat. In female F344 rats implanted with the 13762 mammary tumor, 4 weeks of xerosin II treatment prolonged the survival of rats by an average of 5-11 days (12-24%) in two separate trials. Tumor growth and incidence of metastasis appeared unaffected by xerosin II treatment. Thus, this refined bacterial extract proved to be a potent biological response modifier in four different rodent systems.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2001

Isolation and characterization of Achromobacter xylosoxidans T7 capable of degrading toluidine isomers.

A bacterial strain capable of utilizing toluidine isomers as its sole source of carbon and energy for growth was isolated from contaminated soil. The isolate was identified as Achromobacter xylosoxidans and was designated strain T7. Strain T7 differs from other toluidine-degrading strains with respect to the use of all three toluidine isomers even as an equimolar mixture. Additionally, strain T7 harbours the ability to use aniline, phenol, and cresols as growth substrates. Utilization of the toluidine isomers was demonstrated by an increase in the bacterial biomass concomitant with a decrease of the respective toluidine concentration in liquid medium with this compound as sole source of carbon and energy. No accumulation of any intermediate was detectable by HPLC-analyses. Results of oxygen uptake experiments with resting cells of strain T7 pre-grown on the respective toluidine and enzymatic investigations in cell-free extracts indicate the metabolization of the toluidines via the respective methylcatechols as intermediates. These compounds are substrates for the meta-cleavage pathway initiated by inducible catechol 2,3-dioxygenase found in toluidine-grown cells of strain T7.

Betaproteobacteria↗
PubMed1978

Continuous production of NADP by immobilized Achromobacter aceris cells.

Several microorganisms having higher nicotinamide adenine dinucleotide kinase (NAD kinase, EC 2.7.1.23) activity were immobilized into polyacrylamide gel lattices. The enzyme activity field by immobilization was highest in Achromobacter aceris AKU 0120. By the incubation of the immobilized A. aceris cells at pH 4.0, the NAD kinase activity increased and the adenosine triphosphate (ATP)-degradation activity disappeared completely. Enzymatic properties of the immobilized A. aceris cells were investigated and compared with those of intact cells. The optimal pH and the optimal temperature of immobilized cells were the same as those of intact cells. Immobilized cell NAD kinase was more stable than that of intact cells. The operational half-life of immobilized cells was 20 days when the substrate solution was passed through a column packed with immobilized cells at a flow rate which gives a space velocity (SV) of 0.1 hr-1 at 37 degrees C. On the other hand, the half-life of the intact cells was only 6 hr.

Adenosine Triphosphate↗
PubMed1977

[Physiology of aniline catabolism by achromobacter Ir2].

A bacterium was isolated from soil which utilizes aniline as sole source of carbon and nitrogen. It was identified as Achromobacter sp. The cells grow at concentrations in the range of 0.5 to 1.25 mg aniline/ml with a growth rate of 0.3 h-1. Substrate inhibition was observed at concentrations higher than 1.5 mg/ml, 3.0 mg/ml completely inhibit the growth. The yield coefficient was 0.63. Aniline was degraded with an activity of 200 microng/mg cell dry weight/hour. Aniline was assimilated and completely degraded. The remaining nitrogen was quantitatively detected as ammonia. The enzyme system involved in aniline degradation was induced by aniline but not repressed by succinate and ammonia.

Alcaligenes↗
PubMed1994

Replacement of methionine as the axial ligand of Achromobacter cycloclastes cytochrome c554 at high pH values revealed by absorption, EPR and MCD spectroscopy.

Cytochrome c554 from the denitrifying bacterium Achromobacter cycloclastes is a monoheme class II c-type cytochrome with a His-Met axial coordination at neutral pH. The amino acid composition and the N-terminal sequence of the cytochrome have been determined. Subsequent determination of the pH-dependence of the redox potential and examination of the EPR and MCD spectra of ferricytochrome c554 revealed a new form at high pH values made apparent with both spectroscopies. These observations are consistent with the presence of lysine as the axial ligand for which methionine substitutes at high pH values.

Alcaligenes↗
PubMed1996

Cloning, characterization, and expression of the nitric oxide-generating nitrite reductase and of the blue copper protein genes of Achromobacter cycloclastes.

The nitrite reductase (NIR) and blue copper protein (BCP) genes have been cloned from Achromobacter cycloclastes and characterized. NIR gene encodes a protein of 378 amino acid residues including a putative signal peptide of 37 residues. BCP gene encodes a protein of 148 residues with a 24-residue signal peptide. The DNA-derived amino acid sequence of NIR is in complete agreement with that from Edman degradation and the DNA coding sequence of BCP is also consistent with its partial N-terminal amino acid sequence. Both genes contain their own FNR box in the 5' upstream region and a TA-rich region that could be the transcription start site. These two genes are separated by at least 10 kb. Based on these observations it is very likely that these two genes, although functionally related, are regulated independently. Both proteins could be expressed in E. coli, and both of the expressed proteins could be recognized by their respective antisera. The expressed NIR demonstrates full enzymatic activity. The similarity of both proteins to the counterparts from Alcaligenes faecalis S-6 is discussed.

Alcaligenes↗
PubMed1998

The covalent structure of the blue copper-containing nitrite reductase from Achromobacter xylosoxidans.

The complete amino acid sequence of the blue copper-containing nitrite reductase enzyme (NiR) from Achromobacter xylosoxidans has been determined by chemical analysis, supported by high precision mass analysis. The polypeptide chain contains 336 residues with an overall charge of 0, including the +2 state of each of the copper ions. The two NiR enzymes for which the three-dimensional structures have been solved are green in color and have different absorption spectra than those of the blue-colored protein from A. xylosoxidans. The ligands to the two copper atoms are conserved. Therefore, the difference between the blue and the green NiR must depend on subtle changes in the geometry of the type I copper-sulfur bond. Both overall protein charge and active site charge are different in A. xylosoxidans NiR which may reflect the use of azurin as electron donor as opposed to the other enzymes that use pseudoazurin.

Alcaligenes↗