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PubMed1986

Acinetobacter bacteriocin typing.

A technique for typing Acinetobacter sp. by bacteriocin production has been developed. One hundred and seventy-six cultures from patients in outbreaks, in the community and environmental sources were identified, tested for sensitivity to gentamicin and bacteriocin typed; 154 were A. anitratus and the remainder A.lwoffi. Only one A.lwoffi strain produced bacteriocin. Ten of 22 were sensitive to bacteriocins and could be used as indicators. A close association was found between bacteriocin production and gentamicin resistance: MIC 4 mg/ml. Using six indicator strains 100/104 (96%) gentamicin-resistant strains were typed with nine distinct patterns of inhibition. Overall typability was 65% but 100/176 (56%) fell into only two groups. The technique may be of value in studying the epidemiology of Acinetobacter.

Acinetobacter↗
PubMed1990

Nosocomial outbreaks due to amikacin-resistant tobramycin-sensitive Acinetobacter species: correlation with amikacin usage.

Fifty-seven patients in the Val-de-Grâce hospital were infected or colonized with amikacin-resistant, tobramycin-sensitive Acinetobacter spp. between January 1985 and December 1987. This resistance phenotype was attributed to the recently described 3'-O-aminoglycoside phosphotransferase (APH(3')-VI), on the basis of substrate profile and DNA-DNA hybridization, and was mainly encountered in various biotypes of A. baumannii isolated from patients. It was also encountered in saprophytic A. johnsonii isolates from the hands of 11 healthy workers among the medical staff, which provided evidence for the dissemination of an epidemic gene among different biotypes and species of Acinetobacter. A retrospective epidemiological survey showed a significant correlation between amikacin consumption and case incidence in the wards where cross-infection had occurred.

Acinetobacter Infections↗
PubMed1983

Infection with Acinetobacter in a burns unit.

In recent months 17 patients on the Burns Unit at St Lawrence Hospital have been infected with Acinetobacter anitratus. We present 4 patients who have been extremely ill and in whom Acinetobacter was considered to have played a prominent role. We stress the importance of opportunistic infection in burns patients and antibiotic resistance in this organism.

Acinetobacter Infections↗
PubMed1990

Epidemiological typing of Acinetobacter strains by esterase electrophoresis.

Fifty-three strains of Acinetobacter, belonging to the species A baumannii, A. haemolyticus and A. johnsonii, were differentiated by electrophoretic typing of their esterases, on the basis of both the enzyme specific activity profiles and their electrophoretic mobilities. Each esterase was defined by its spectrum of hydrolytic activity toward five synthetic substrates and its sensitivity to di-isopropyl fluorophosphate. Since each enzyme was not detected in all strains of a given species, several zymotypes could be defined by the patterns of combinations of esterases. Thus, 24 zymotypes were defined in the 32 A. baumannii strains, 4 were defined in the 10 A. haemolyticus strains and 6 were defined in the 11 A. johnsonii strains. When the electrophoretic mobilities of the various esterases were included, each of the 53 strains of Acinetobacter (with the exception of three A. haemolyticus strains) showed a distinct electrotype.

Acinetobacter↗
PubMed1994

Cloning and expression in Escherichia coli of the gene encoding a novel L-2,4-diaminobutyrate decarboxylase of Acinetobacter baumannii.

The gene encoding L-2,4-diaminobutyrate decarboxylase (DABA DC) was cloned from Acinetobacter baumannii ATCC 19606. The gene was evidently under the control of its own promoter. Interestingly, the host carrying this clone also produced an appreciable amount of 1,3-diaminopropane. Restriction mapping and subsequent subcloning of the cloned insert localized the DABA DC gene within a 2.45-kb SphI/EcoRI fragment. For endogenous production of DAP, a 1.75-kb EcoRI/PstI region downstream from the DABA DC gene was further required. Southern blot hybridization revealed some heterogeneity in the DABA DC genes among other Acinetobacter species.

Acinetobacter↗
PubMedDate not supplied

Degradation of non-phenolic beta-o-4 lignin substructure model compounds by Acinetobacter sp.

Acinetobacter sp. utilized non-phenolic beta-o-4-model compounds, 2-methoxy-4-formylphenoxyacetic acid and veratrylglycerol-beta-guaiacyl ether (VGE) as sole carbon source. Vanillin, vanillic acid, protocatechuic acid and catechol were detected in the 2-methoxy-4-formylphenoxyacetic acid amended culture. Veratryl alcohol, veratraldehyde, veratric acid, vanillic acid, protocatechuic acid, catechol and guaiacol were identified from veratrylglycerol-beta-guaiacyl ether culture. Acinetobacter sp. produced catechol 1,2-dioxygenase and protocatechuate 3,4-dioxygenase that cleaved catechol and protocatechuic acid, respectively.

Acinetobacter↗
PubMed2004

Isolation of a member of Acinetobacter species involved in atrazine degradation.

Contribution of Acinetobacter genus in the degradation of atrazine and its analogs is reported here. An interesting bacterial isolate capable of degrading atrazine as high as 250 ppm was isolated from a soil heavily contaminated with atrazine. The permissible level of atrazine in drinking water is 3 ppb and hence use of a strain capable of atrazine degradation as high as 250 ppm would be of immense help for rapid environmental cleanup. This isolate was found to be capable of best growth at 37 degrees C and at pH inclined towards the alkaline side. It was found that atrazine was utilized as a carbon and not as a nitrogen source. Acinetobacter species was also active on other triazine pesticides, viz., simazine, terbutryn, cyanazine, and prometon. There are very few reports on the degradation of atrazine by any member of this genus and hence this could lead to new degradation pathways and new metabolites.

Acinetobacter↗
PubMed2004

Gene amplification involves site-specific short homology-independent illegitimate recombination in Acinetobacter sp. strain ADP1.

A system for studying gene amplification in the bacterium Acinetobacter sp. strain ADP1 was used to isolate 105 spontaneous mutants. The method selects for the elevated expression of neighboring transcriptional units in a parent strain lacking its normal transcriptional activators. Gene amplification can compensate for the activator loss by increasing the copy number of seven weakly expressed genes. Mutant colonies arose from the parent strain at a frequency of 10(-8) within three weeks. All but one of these mutants carried tandem head-to-tail repeats of a chromosomal segment (amplicon). These amplicons varied in size from approximately 12-290 kb and ranged in copy number from 3 to more than 30. Gene amplification involved a two-step process in which duplications formed independently of recA. Illegitimate recombination fused normally distant chromosomal regions to create novel DNA duplication junctions. These junctions were isolated from amplification mutants using an assay that exploits Acinetobacter natural transformability. Sequence analysis of 72 junctions revealed little identity in the recombining regions. Furthermore, multiple independently isolated mutants contained identical junctions. Six different junctions, each found in two to six mutants, revealed that some recombination events are site-specific. Several recurring junctions were studied using PCR. In each case, the identical duplication present in the mutant was estimated to have occurred in as many as one in a million cells in populations of strains never exposed to selective conditions. These duplications appeared to form spontaneously by a novel type of short homology-independent, site-specific process. However, in the absence of recA, mutant colonies were not selected from parent cells containing these duplications. Thus, the second gene amplification step most likely depends on homologous recombination to increase amplicon copy number. These studies support the theory that gene amplification is a driving force in the evolution of functionally related gene clusters.

Acinetobacter↗
PubMed2006

[Prevalence of Acinetobacter baumannii and Pseudomonas aeruginosa isolates resistant to imipenem by production of metallo-beta-lactamase].

UNLABELLED: Metallo-beta-lactamases (MBL) are enzymes produced by Gram-negative bacilli such as Pseudomonas aeruginosa and Acinetobacter baumannii. These enzymes make these isolates resistant to imipenem. AIM: The aim of this study was to determine the prevalence of this resistance mechanism in Pseudomonas aeruginosa and Acinetobacter baumannii strains identified in the bacteriology laboratory of the Rabat Ibn Sina teaching hospital, Morocco. MATERIALS AND METHOD: Screening for MBL was systematic in all resistant strains and/or strains with decreased sensitivity to imipenem, according to Dongeun Yong et al.'s method, using a sterilized solution of EDTA 0.5 M pH 8. RESULTS: Eighty-five bacterial strains (48 P. aeruginosa and 37 A. baumannii) were identified 23% (11) and 57% (21) of which were respectively resistant to the imipenem. The prevalence of MbetaL producing strains was 27% for P. aeruginosa and 38% for A. baumannii. CONCLUSION: These results show that the frequency of these strains is increases in our hospital and that their emergence represents a serious therapeutic and epidemiological problem. This means that we need to implement the supervision of hospital microbial environment and strictly apply hygiene measures.

Acinetobacter↗
PubMed2006

Sequence and organization of pMAC, an Acinetobacter baumannii plasmid harboring genes involved in organic peroxide resistance.

Acinetobacter baumannii 19606 harbors pMAC, a 9540-bp plasmid that contains 11 predicted open-reading frames (ORFs). Cloning and transformation experiments using Acinetobacter calcoaceticus BD413 mapped replication functions within a region containing four 21-bp direct repeats (ori) and ORF 1, which codes for a predicted replication protein. Subcloning and tri-parental mating experiments mapped mobilization functions to the product of ORF 11 and an adjacent predicted oriT. Three ORFs code for proteins that share similarity to hypothetical proteins encoded by plasmid genes found in other bacteria, while the predicted products of three others do not match any known sequence. The product of ORF 8 is similar to Ohr, a hydroperoxide reductase responsible for organic peroxide detoxification and resistance in bacteria. This ORF is immediately upstream of a coding region whose product is related to the MarR family of transcriptional regulators. Disk diffusion assays showed that A. baumannii 19606 is resistant to the organic peroxide-generating compounds cumene hydroperoxide (CHP) and tert-butyl hydroperoxide (t-BHP), although to levels lower than those detected in Pseudomonas aeruginosa PAO1. Cloning and introduction of the ohr and marR ORFs into Escherichia coli was associated with an increase in resistance to CHP and t-BHP. This appears to be the first case in which the genetic determinants involved in organic peroxide resistance are located in an extrachromosomal element, a situation that can facilitate the horizontal transfer of genetic elements coding for a function that protects bacterial cells from oxidative damage.

Acinetobacter baumannii↗
PubMed2003

Proteomic analysis of the benzoate degradation pathway in Acinetobacter sp. KS-1.

The purpose of this study was to perform proteome analysis of Acinetobacter sp. KS-1, a bacterium capable of degrading benzoate as a sole carbon source. In order to understand the benzoate degradation pathway used by strain KS-1, proteomes of benzoate-cultured and succinate-cultured KS-1 were comparatively analyzed by two dimensional gel electrophoresis (2-DE). Eighteen protein spots proteins were exclusively induced from the benzoate-cultured strain KS-1. Of these 18 spots, two benzoate-degrading enzymes (catechol 1,2-dioxygenase and beta-ketoadipate succinyl-CoA transferase) were identified by MS/MS analysis by MALDI-TOF/TOF mass spectrometry, which suggests that strain KS-1 degrades benzoate by the beta-ketoadipate pathway. DEAE-chromatography suggested that strain KS-1 induced only one type of catechol 1,2-dioxygenase during benzoate degradation. The catechol 1,2-dioxygenase was purified using three steps of ammonium sulfate precipitation, DEAE-sepharose, and Mono-Q chromatography. The purified catechol 1,2-dioxygenase of strain KS-1 had strong dioxygenase activity for 4-methylcatechol as well as catechol. Sequencing analysis using N-terminal and internal amino acid sequences showed that this catechol 1,2-dioxygenase is highly homologous with catechol 1,2-dioxygenase of Acinetobacter radioresistens. These results suggest that comparative proteomic analysis of biodegrading bacteria cultured under different conditions may be a useful initial step toward the elucidation of the aromatic compound degradation pathway.

Acinetobacter↗
PubMed2006

The beta-lactamase threat in Enterobacteriaceae, Pseudomonas and Acinetobacter.

Over the past 60 years, the use of successive generations of beta-lactam antibiotics has selected successive generations of beta-lactamase enzymes, each more potent than the last. Currently, rising problems include CTX-M extended-spectrum beta-lactamases (ESBLs), plasmid-mediated AmpC beta-lactamases and KPC carbapenemases in Enterobacteriaceae, while OXA- and metallo- carbapenemases are of growing importance in Acinetobacter spp. and (less so) in other non-fermenters. Escherichia coli isolates with CTX-M ESBLs are spreading multiresistance in the community and in hospitals, while carbapenemase-producing Acinetobacter spp., mostly from intensive care, are among the most multiresistant nosocomial bacteria known and are often susceptible only to polymyxins and, potentially, tigecycline. This review discusses the epidemiology and microbiology of these resistance problems, along with possible solutions.

Acinetobacter↗
PubMed1997

Purification, biochemical properties and substrate specificity of a catechol 1,2-dioxygenase from a phenol degrading Acinetobacter radioresistens.

A catechol 1,2-dioxygenase (C1,2O) has been purified to homogeneity from Acinetobacter radioresistens grown on phenol as the sole carbon and energy source. The C1,2O appears to be a homodimer, with a molecular mass of 78,000 Da. At relatively high ionic strengths (0.5 M Na2SO4) subunit dissociation occurs and the monomeric unit (38,700 Da) is shown to be active. This phenomenon has never been observed before in dioxygenases. The purified C1,2O contains 0.96 iron(III) ions per unit and spectroscopic measurements suggest the presence of one high-spin iron(III) ion in an environment characteristic of intradiol cleaving enzymes. The NH2-terminal amino acid sequence has been determined and compared to the primary structures of intradiol rings cleaving dioxygenases from other Acinetobacter strains revealing 45% homology with the benzoate-grown A. calcoaceticus ADP-1 and an identity of only one of the 20 amino acids sequenced for the phenol-grown A. calcoaceticus NCIB 8250.

Acinetobacter↗
PubMed1999

Endocarditis due to Acinetobacter lwoffi on native mitral valve.

Endocarditis due to Acinetobacter is a rare pathology with high mortality, reported mainly in hospitalized patients with predisposing risk factors. This is the second case of endocarditis due to Acinetobacter reported in our country in the last 10 years.

Acinetobacter Infections↗
PubMed1989

Acinetobacter peritonitis during chronic peritoneal dialysis.

Among gram-negative bacilli isolated during peritonitis in chronic peritoneal dialysis (CPD), Pseudomonas species are most common but Acinetobacter species are nearly as frequent. A survey of more than 450 patient-years' experience with CPD revealed 23 episodes of Acinetobacter peritonitis (AP), making this the second most common form of gram-negative peritonitis. Concomitant break in sterile technique and exit-site/tunnel infection were infrequent. AP appeared as the first peritonitis episode in five cases and as the second in six cases, and the duration of CPD at the time of AP ranged from less than 1 to greater than 56 months. However, AP was noted to appear shortly after treatment of another peritonitis episode or shortly after CPD access placement, within 2 months in 11 cases (47%) and within 3 months in 14 cases (61%). Treatment with intraperitoneal antibiotics succeeded in 21 cases (91%) without CPD interruption or catheter removal, with tobramycin or gentamicin alone in 16 cases, and with combined aminoglycoside and penicillin or cephalosporin in six cases. In two cases intraperitoneal antibiotics alone were insufficient therapy: one case with concomitant tunnel infection and dialysate leak and one case with bacteremia while receiving corticosteroids. The time-dependent incidence of AP suggests opportunistic infection during a vulnerable period in the first 2 to 3 months following another peritonitis episode, but AP also appears amenable to intraperitoneal antibiotic therapy alone without interruption of the CPD routine in the majority of cases.

Acinetobacter Infections↗
PubMed1998

[Dehiscence of a composite aortic graft (Bono and Bentall technique) secondary to Acinetobacter endocarditis].

Acinetobacter sp. are gram-negative bacteria and usually resistant to multiple antibiotics. They are a customary cause of nosocomial infections, but are uncommon etiologic agents of endocarditis. We present a case of endocarditis caused by Acinetobacter iwoffi in a composite aortic graft with a St. Jude prosthetic valve, using the Bono and Bentall procedure, complicated with multiple graft dehiscenses causing first a peritube pseudoaneurysm and finally severe paraprosthetic valve regurgitation to the left ventricle which required emergency surgery.

Acinetobacter Infections↗
PubMed2003

Implications for Burns Unit design following outbreak of multi-resistant Acinetobacter infection in ICU and Burns Unit.

We reviewed the emergence of 13 cases of multi-resistant Acinetobacter infection in burns patients over a 12-month period. The outbreak was started in a non-burn patient in the intensive care unit (ICU) that spread to burns patients in ICU and then the Burns Unit. The importance of opportunistic infection, potential risk factors, treatment and clinical outcome of Acinetobacter infection in burns patients from this cluster of cases is described. This paper implicates the movement of burns patients and medical equipment between ICU and the Burns Unit in the spread of this infection. Future design of Burn Units should aim to incorporate features to allow the management of all burns cases in one location with all intensive care, burns and theatre facilities built in close proximity.

Acinetobacter Infections↗
PubMed1997

Uptake and processing of DNA by Acinetobacter calcoaceticus--a review.

In natural transformation, DNA in the form of macromolecular fragments can be translocated across the cell envelope of prokaryotic microorganisms. During the past two decades, several, largely mutually contradictory, hypotheses have been forwarded to explain the molecular mechanism and bioenergetics of this translocation process. Other biomacromolecules are translocated across the bacterial cell envelope as well, such as polysaccharides and proteins, the latter for instance in the process of the assembly of type-IV pili. This brings up the question whether or not common components are involved. Here, we review analyses of DNA translocation in Acinetobacter calcoaceticus, a Gram-negative eubacterium that is able to migrate through twitching motility, and also shows a high frequency of natural transformation. DNA uptake in this organism is an energy-dependent process. Upon entry into the cells, the DNA fragments are integrated into the resident chromosome when a sufficiently large region of mutual homology is available (200 to 400 bp). However, this process is rather inefficient, and on the average 500 bp of each incoming fragment is degraded through exonuclease activity. Upon covalent attachment of a bulky protein molecule to the transforming DNA, the DNA-translocation machinery becomes blocked in further translocation activity. Since A. calcoaceticus is not well suited for transposon mutagenesis, a random mutagenesis procedure has been developed, based on the ligation of an antibiotic-resistance marker to random fragments of chromosomal DNA. This method was used to generate several mutants impaired in the natural transformation process. Three of these have been characterized in detail. No components, common to the translocation of macromolecules through the cell envelope of Acinetobacter, have been detected in this screen.

Acinetobacter calcoaceticus↗