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At least 19 recordsLinked to original sources
PubMed1994

Characterization of the chromosomal aac(6')-Ij gene of Acinetobacter sp. 13 and the aac(6')-Ih plasmid gene of Acinetobacter baumannii.

The amikacin resistance genes aac(6')-Ih of Acinetobacter baumannii BM2686 and aac(6')-Ij of Acinetobacter sp. 13 BM2689 encoding aminoglycoside 6'-N-acetyltransferases were characterized. The 441-bp coding sequences predict proteins with calculated masses of 16,698 and 16,677 Da, respectively. Analysis of the deduced amino acid sequences indicated that the proteins belonged to a subfamily of 6'-aminoglycoside acetyltransferase type I enzymes from gram-negative bacteria. The aac(6')-Ih gene of BM2686 was located on a 13.7-kb nonconjugative plasmid. The aac(6')-Ij gene from BM2689 was not transferable either by conjugation to Escherichia coli or A. baumannii or by transformation to Acinetobacter calcoaceticus. Plasmid DNA from BM2689 did not hybridize with an intragenic aac(6')-Ij probe. These results suggest a chromosomal location for this gene. The aac(6')-Ij gene was detected by DNA hybridization in all 28 strains of Acinetobacter sp. 13 tested but not in other Acinetobacter strains, including A. baumannii, proteolytic genospecies 4, 6, 14, 15, 16, and 17, and ungrouped strains. The aac(6')-Ih and -Ij probes did not hybridize in dot blot assays with DNA from members of the families Enterobacteriaceae and Pseudomonadaceae that produced 6'-N-acetyltransferases. These data suggest that the genes are confined to the Acinetobacter genus and that the aac(6')-Ij gene is species specific and may be used to identify Acinetobacter sp. 13.

Acetyltransferases↗
PubMed1994

Description of Leeds Acinetobacter Medium, a new selective and differential medium for isolation of clinically important Acinetobacter spp., and comparison with Herellea agar and Holton's agar.

Acinetobacter spp. are responsible for an increasing number of opportunistic, nosocomial infections. They have been isolated from diverse inanimate objects in the hospital environment and are resistant to most of the commonly used antibiotics. Existing media for the isolation of Acinetobacter spp. are either nonselective, allowing the growth of unwanted bacteria, or too inhibitory, inhibiting the growth of many Acinetobacter strains. For the rapid isolation and effective control of Acinetobacter infection, a new selective and differential medium, Leeds Acinetobacter Medium (LAM), has been developed to isolate Acinetobacter spp. from clinical and environmental sources. The concentration of antibiotics and other ingredients in this medium have been determined according to the results of MIC and viable counts performed for these ingredients. LAM was compared with other selective and differential media for the isolation of Acinetobacter spp. from a local hospital environment and proved to be better in terms of recovery and selectivity.

Acinetobacter↗
PubMedDate not supplied

Bacteremia due to Acinetobacter species other than Acinetobacter baumannii.

The objective of this study was to describe the clinical features, possible predisposing factors and treatment outcomes associated with bacteremia du to Acinetobacter species other than Acinetobacter baumannii. A review of laboratory and medical charts over a period of 18 months revealed 61 cases of bacteremia due to Acinetobacter species other than A. baumannii occurring in 59 patients. Six of these were considered not significant. Fifty cases represented catheter-related bacteremia, one case was associated with meningitis following brain surgery, and four cases could not be classified. Clinical courses wre usually benign: all but four patients were cured, but death was not related to Acinetobacter bacteremia in any case. Therapy included catheter removal alone (32.8%), appropriate antimicrobials alone (12.7%), or both (49.1%). Plasmid analysis showed distinct patterns in all strains isolated from different patients and did not reveal any epidemiological relationship among cases. Acinetobacter species other than A. baumannii are clinically significant organisms with limited pathogenic potential. They are almost exclusively involved in devise-related bacteremia. Clinical and epidemiological features of infections due to these organisms are clearly distinct from infections due to A. baumannii.

Acinetobacter↗
PubMed1990

[Spontaneous transformation in mixed cultures of various types of Acinetobacter and during joint growth of Acinetobacter calcoaceticus with Escherichia coli and Pseudomonas aeruginosa].

The transfer of chromosomal and plasmid genes was studied via spontaneous transformation is mixed cultures of Acinetobacter spp. It turned out that any Acinetobacter strain, irrespective of its species specificity, serves as chromosomal DNA donor in case the mixed culture contains competent cells of the recipient strain. No transfer took place when non-related bacteria were used as donors. We also studied the transfer into Ac. calcoaceticus competent strain cells of small non-conjugative plasmids having broad host range (RSF1010, pAK1). In these cases, DNA donors could be not only acinetobacters of other species, but bacteria belonging to other systematic groups (families)--E. coli and P. aeruginosa. The transfer of plasmids from cells of unrelated bacteria took place with a frequency of about 10(-5)-10(-6). The possible role of spontaneous transformation in horizontal gene transfer is discussed.

Acinetobacter↗
PubMed1992

Ribotyping of the Acinetobacter calcoaceticus-Acinetobacter baumannii complex.

The Acinetobacter calcoaceticus-Acinetobacter baumannii complex consists of four genotypically distinct but phenotypically very similar bacterial species or DNA groups: A. calcoaceticus (DNA group 1), A. baumannii (DNA group 2), unnamed DNA group 3 (P. J. M. Bouvet and P. A. D. Grimont, Int. J. Syst. Bacteriol. 36:228-240, 1986), and unnamed DNA group 13 (I. Tjernberg and J. Ursing, APMIS 97:595-605, 1989). Because strains in this complex cause nosocomial outbreaks, it is important to be able to identify them as completely as possible. Ribotyping could provide such identification. Therefore, ribotyping was done on 70 strains in the A. calcoaceticus-A. baumannii complex with known DNA group affiliations by use of restriction enzymes EcoRI, ClaI, and SalI. A nonradioactive digoxigenin-11-dUTP-labeled Escherichia coli rRNA-derived probe was used. With any of the three restriction enzymes, banding patterns that were specific for each DNA group were seen. All 70 strains showed banding patterns that could identify them to the correct DNA group by use of any two of the three enzymes. In addition, banding patterns that could separate strains within any one DNA group were present. The discriminatory index of P. Hunter and M. Gaston (J. Clin. Microbiol. 26:2465-2466, 1988), applied to all strains with the combined results obtained with all three enzymes, revealed a value of 0.99. For strains in each DNA group, the value varied from 0.93 to 0.98. These results indicate the high discriminatory power of the system when used for epidemiological typing.

Acinetobacter↗
PubMed1992

Susceptibility of isolates of Acinetobacter anitratus and Acinetobacter lwoffii to the bactericidal activity of normal human serum.

The bactericidal activity of normal human serum against the Gram-negative coccobacilli Acinetobacter anitratus and Acinetobacter lwoffii was studied; 12% and 84%, respectively, of the tested strains appeared to be sensitive. Thus, serum resistance may be an important factor contributing to the pathogenic potential of A. anitratus strains. Three types of bactericidal action were shown. In the first, the strains were killed when the alternative complement pathway was activated. In the second, some strains required both the classical and alternative pathways. In the third variant, the strains needed either the alternative or classical activation pathway.

Acinetobacter↗
PubMed1978

Metabolism of bile acids by strains of Acinetobacter anitratum and Acinetobacter lwoffii.

The activity of two species of bacteria: Acinetobacter anitratum and Acinetobacter lwoffii, isolated from jejunum of patients with achlorhydria and Reichel-Polya resection towards bile salts was investigated. These species were not previously tested from this view point. All strains tested hydrolyzed bile salts; conjugates of deoxycholic acid were hydrolyzed more readily than those of cholic acid. This feature may be used as a bacteriological taxonomic criterion.

Acinetobacter↗
PubMed1972

Interspecies transformation of Acinetobacter: genetic evidence for a ubiquitous genus.

The availability of a strain of Acinetobacter competent for transformation has made it possible to demonstrate the genetic relatedness of a large variety of gram-negative, oxidase-negative, nonmotile, and aerobic coccobacilli originally classified into eleven different genera. Deoxyribonucleic acid (DNA) species from 265 such strains are capable of transforming stable auxotrophs of the competent Acinetobacter to prototrophy. The compositions of these DNA species vary from 40 to 46.8% guanine plus cytosine. Strains with widely differing phenotypic properties are also included in this collection of acinetobacters. DNA species from all oxidase-positive strains of Moraxella and from a variety of common bacteria are unable to transform the competent Acinetobacter. Although acinetobacters are usually considered to be unable to reduce nitrate to nitrite, six strains known to carry out this reduction have been shown to be authentic acinetobacters since their DNA species readily transform the competent Acinetobacter auxotrophs to prototrophy. In contrast to previous findings that acinetobacters rarely grow with glucose as a sole carbon source, the results of the present study show that 17 of the 265 strains grow readily in a glucosemineral medium, and 48 other strains can mutate spontaneously to grow in such a medium. A second competent strain of Acinetobacter, originally unable to use glucose, d-xylose, or d-ribose as carbon sources, has been transformed for ability to dissimilate these compounds using DNA species from strains that normally grow on these sugars. Although most of the 265 Acinetobacter strains studied were originally grown on complex media when isolated from human sources, only nine of these strains require growth factors in order to grow in a mineral medium containing a single carbon and energy source. A simple transformation assay has been devised for rapid examination of large numbers of strains to determine whether or not they are acinetobacters. This assay, which is suitable for routine diagnostic work, includes a procedure for preparation of crude transforming DNA from a small quantity of bacterial paste. Samples of DNA prepared from Acinetobacter cultures that had died on slants and plates were still able to effect transformation of the competent auxotrophs to prototrophy.

Aerobiosis↗
PubMed1982

Progressive resistance in a single strain of Acinetobacter calcoaceticus recovered during a nosocomial outbreak.

A study was undertaken to investigate a nosocomial outbreak of acinetobacter calcoaceticus. The outbreak occurred in a shock-trauma intensive care unit (ICU) during a 6-month period and involved a total of 37 cases. Although no deaths were attributable to Acinetobacter, 60% of patients from whom Acinetobacter was isolated were determined to have a lower respiratory tract infection. A significant difference (p less than 0.05) was noted between the length to stay in the unit of patients who acquired Acinetobacter (mean 23.9 days) and of those who remained free of the organism (mean 2.58 days). The average day on which cultures first became positive was 14.85. During the last 3 months of the outbreak, the ICU Acinetobacter isolates developed an unusual pattern of aminoglycoside resistance that differed significantly (p less than 0.001) from the sensitivities of non-ICU Acinetobacter isolates. No plasmids could be detected in selected aminoglycoside-resistance Acinetobacter. Pseudomonas aeruginosa isolated concurrently from patients with Acinetobacter showed no abnormal variation in antimicrobial sensitivities. These findings were interpreted to mean that the outbreak was the result of the persistence of a single strain of A. calcoaceticus within the ICU. Termination of the outbreak was attributed to initiation of control measures.

Acinetobacter↗
PubMed1995

Clinical and epidemiological features of an outbreak of acinetobacter infection in an intensive therapy unit.

Sporadic examples of infection with multi-resistant Acinetobacter spp. have occurred in Nottingham hospitals since at least 1977, punctuated by more prolonged outbreaks involving larger numbers of patients, particularly those confined to the intensive therapy unit (ITU) with severe underlying disease. In the most recent outbreak, 11 patients were infected with multi-resistant Acinetobacter strains and 26 patients were colonised. Four of the infected patients died directly or indirectly from infection with multi-resistant Acinetobacter spp., either while in the ITU or after discharge to a general ward. The mean interval from admission to the first isolation of a multi-resistant Acinetobacter strain was 6.7 and 12.1 days in the infected and colonised groups, respectively. Multi-resistant Acinetobacter strains were isolated most frequently from the respiratory tract, and eight patients had probable or suspected pneumonia caused by a multi-resistant Acinetobacter sp. All infected patients were treated with imipenem, with or without an aminoglycoside, except one patient who died before a diagnosis of acinetobacter infection was confirmed. Multi-resistant Acinetobacter spp. were isolated from various environmental sites in the ITU, and patient and environmental isolates were found to be related closely by biotyping, antibiograms, pulsed-field gel electrophoresis of chromosomal fingerprints and ribotyping. The outbreak was controlled ultimately by transfer of infected or colonised patients to an isolation cubicle, cohort nursing, emphasis on the importance of hand washing before and after patient contact and when handling case notes, and the use of disposable aprons and gowns during patient contact.(ABSTRACT TRUNCATED AT 250 WORDS)

Acinetobacter↗