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PubMed2000

Nosocomial bloodstream infections caused by Acinetobacter species in United States hospitals: clinical features, molecular epidemiology, and antimicrobial susceptibility.

We examined the clinical and epidemiological features of nosocomial bloodstream infections (BSIs) caused by Acinetobacter species and observed from 1 March 1995 through 28 February 1998 at 49 United States hospitals (SCOPE National Surveillance Program). Acinetobacter species were found in 24 hospitals (49%) and accounted for 1.5% of all nosocomial BSIs reported. One hundred twenty-nine isolates were identified either as A. baumannii (n=111) or other Acinetobacter species (n=18). Patients with A. baumannii BSI, compared with patients with nosocomial BSI caused by other gram-negative pathogens, were more frequently observed in the intensive care unit (69% vs. 47%, respectively; P<.001; odds ratio [OR] 2.4; 95% confidence interval [CI] 1.6-3.7) and were more frequently receiving mechanical ventilation (58% vs. 30%, respectively; P<.001; OR 3.2; 95% CI 2.1-4.8). Crude mortality in patients with A. baumannii BSI was 32%. Molecular relatedness of strains was studied by use of polymerase chain reaction-based fingerprinting. Clonal spread of a single strain occurred in 5 hospitals. Interhospital spread of epidemic A. baumannii strains was not observed. The most active antimicrobial agents against A. baumannii (90% minimum inhibitory concentration values) were imipenem (1 mg/L; 100% of isolates susceptible), amikacin (8 mg/L; 96%), tobramycin (4 mg/L; 92%), and doxycycline (4 mg/L; 91%). Thirty percent of isolates were resistant to > or =4 classes of antimicrobials and were considered to be multidrug resistant.

Acinetobacter↗
PubMed2004

Genotypic characterization of carbapenem-nonsusceptible Acinetobacter spp. isolated in Latin America.

The principal aim of this study was to evaluate the genomic diversity among the imipenem-nonsusceptible Acinetobacter spp. (INSA) collected from the Latin American medical centers within the SENTRY Antimicrobial Surveillance Program. The INSA isolates were collected from patients with bloodstream infections, who were hospitalized in seven Latin American countries between 1997 and 1999. For epidemiologic comparison, 20 carbapenem-susceptible Acinetobacter spp. (CSA) isolates were collected in the same period of time from the respective medical centers. A total of 23 Acinetobacter spp. isolates exhibiting imipenem MIC values of >/=8 microg/ml were typed by ribotyping, an automated molecular method. The isolates showing an identical ribogroup were also typed by pulsed-field gel electrophoresis (PFGE). The antimicrobial susceptibility to various antimicrobial agents was evaluated using a reference broth microdilution technique. Among the INSA isolates, 13 distinct ribogroups were observed, whereas 16 ribogroups were detected among the CSA. Nearly 57% of the INSA belonged to only four ribogroups. Identical ribogroups and PFGE patterns were observed among INSA and CSA isolates collected from medical centers located in different countries (Brazil and Argentina). Our results showed: (1) a higher genomic variability among the CSA; (2) presence of epidemic clones among INSA isolates encountered in Latin American medical centers; and (3) spread of INSA and CSA epidemic clones between Latin American countries.

Acinetobacter↗
PubMedDate not supplied

Community-acquired acinetobacter pneumonia in adults in Papua New Guinea.

Acinetobacter calcoaceticus, an aerobic gram-negative coccobacillus, is a rare cause of community-acquired pneumonia. It most commonly causes nosocomial infections, particularly in elderly debilitated patients who have undergone surgery, instrumentation, and antibiotic therapy. In a study of acute pneumonia in adults, five cases of community-acquired acinetobacter pneumonia were observed over an 11-month period. Other than chronic pulmonary disease (two patients), no serious underlying diseases existed in these patients. Lobar consolidation was the predominant radiologic pattern. The mortality rate was 40%, and mortality was directly related to therapy with inappropriate antibiotics. The reason for this relatively high prevalence of community-acquired acinetobacter pneumonia in the population studied is not known. Possible explanations include the high prevalence of chronic pulmonary disease, indiscriminate use of penicillin, and an unknown immunodeficiency state.

Acinetobacter Infections↗
PubMed1995

The comparative inhibitory and bactericidal activities of meropenem and imipenem against Acinetobacter spp. and Enterobacteriaceae resistant to second generation cephalosporins.

The inhibitory and bactericidal activities of meropenem and imipenem were compared using Acinetobacter spp. and Enterobacteriaceae resistant to second generation cephalosporins. The inhibitory activity of both agents was similar for Acinetobacter spp. but meropenem was more active against the Enterobacteriaceae. Bactericidal activities were compared employing time-kill curves which indicated meropenem was more bactericidal than imipenem against Enterobacteriaceae at pharmacologically achievable concentrations while imipenem was more bactericidal than meropenem against Acinetobacter spp.

Acinetobacter↗
PubMed2006

The tetracycline resistance determinant Tet 39 and the sulphonamide resistance gene sulII are common among resistant Acinetobacter spp. isolated from integrated fish farms in Thailand.

OBJECTIVES: To determine the genetic basis for tetracycline and sulphonamide resistance and the prevalence of class I and II integrons in oxytetracycline-resistant Acinetobacter spp. from integrated fish farms in Thailand. METHODS: A total of 222 isolates were screened for tetracycline resistance genes [tet(A), tet(B), tet(H), tet(M) and tet(39)] and class II integrons by PCR. One hundred and thirty-four of these isolates were also sulphonamide resistant and these isolates were screened for sulphonamide resistance genes (sulII and sulIII) as well as class I integrons. Plasmid extraction and Southern blots with sulII and tet(39) probes were performed on selected isolates. RESULTS: The recently identified tetracycline resistance gene tet(39) was demonstrated in 75% (166/222) of oxytetracycline-resistant Acinetobacter spp. from integrated fish farms in Thailand. Isolates that were also sulfamethoxazole-resistant contained sulII (96%; 129/134) and/or sulI (14%; 19/134) (as part of class I integrons). sulII and tet(39) were located on plasmids differing in size in the isolates tested. CONCLUSIONS: The study shows tet(39) and sulII to be common resistance genes among clonally distinct Acinetobacter spp. from integrated fish farms and these bacteria may constitute reservoirs of resistance genes that may increase owing to a selective pressure caused by the use of antimicrobials in the overlaying animal production.

Acinetobacter↗
PubMed2003

Intergeneric transfer of chromosomal and conjugative plasmid genes between Ralstonia solanacearum and Acinetobacter sp. BD413.

Conjugative transfer of a broad-host range plasmid and transformation-mediated transfer of chromosomal genes were found to occur at significant frequencies between Ralstonia solanacearum and Acinetobacter sp. in planta. These intergeneric gene transfers are related to the conditions provided by the infected plant, including the extensive multiplication of these two bacteria in planta and the development of a competence state in Acinetobacter sp. Although interkingdom DNA transfer from nuclear transgenic plants to these bacteria was not detectable, plants infected by pathogens (e.g., Ralstonia solanacearum) and co-colonized by soil saprophyte bacteria (e.g., Acinetobacter sp.) can be considered as potential "hot spots" for gene transfer, even between phylogenetically remote organisms.

Acinetobacter↗
PubMed1994

Phylogenetic relationships between some members of the genera Neisseria, Acinetobacter, Moraxella, and Kingella based on partial 16S ribosomal DNA sequence analysis.

We obtained 16S ribosomal DNA (rDNA) sequence data for strains belonging to 11 species of Proteobacteria, including the type strains of Kingella kingae, Neisseria lactamica, Neisseria meningitidis, Moraxella lacunata subsp. lacunata, [Neisseria] ovis, Moraxella catarrhalis, Moraxella osloensis, [Moraxella] phenylpyruvica, and Acinetobacter lwoffii, as well as strains of Neisseria subflava and Acinetobacter calcoaceticus. The data in a distance matrix constructed by comparing the sequences supported the proposal that the genera Acinetobacter and Moraxella and [N.] ovis should be excluded from the family Neisseriaceae. Our results are consistent with hybridization data which suggest that these excluded taxa should be part of a new family, the Moraxellaceae. The strains that we studied can be divided into the following five groups: (i) M. lacunata subsp. lacunata, [N.] ovis, and M. catarrhalis; (ii) M. osloensis; (iii) [M.] phenylpyruvica; (iv) A. calcoaceticus and A. lwoffii; and (v) N. meningitidis, N. subflava, N. lactamica, and K. kingae. We agree with the previous proposal that [N.] ovis should be renamed Moraxella ovis, as this organism is closely related to Moraxella species and not to Neisseria species. The generically misnamed taxon [M.] phenylpyruvica belongs to the proposed family Moraxellaceae, but it is sufficiently different to warrant exclusion from the genus Moraxella. Further work needs to be done to investigate genetically similar species, such as Psychrobacter immobilis, before the true generic position of this organism can be determined. Automated 16S rDNA sequencing with the PCR allows workers to accurately determine phylogenetic relationships between groups of organisms.(ABSTRACT TRUNCATED AT 250 WORDS)

Acinetobacter↗
PubMed1997

Directed introduction of DNA cleavage sites to produce a high-resolution genetic and physical map of the Acinetobacter sp. strain ADP1 (BD413UE) chromosome.

The natural transformability of the soil bacterium Acinetobacter sp. ADP1 (BD413UE), formerly classified as A. calcoaceticus, has facilitated previous physiological and biochemical investigations. In the present studies, the natural transformation system was exploited to generated a physical and genetic map of this strain's 3780 +/- 191 kbp circular chromosome. Previously isolated Acinetobacter genes were modified in vitro to incorporate a recognition sequence for the restriction endonuclease NotI. Following transformation of the wild-type strain by the modified DNA, homologous recombination placed each engineered NotI cleavage site at the chromosomal location of the corresponding gene. This allowed precise gene localization and orientation of more than 40 genes relative to a physical map which was constructed with transverse alternating field electrophoresis (TAFE) and Southern hybridization methods. The positions of NotI, AscI and I-CeuI recognition sites were determined, and the latter enzyme identified the presence of seven ribosomal RNA operons. Multiple chromosomal copies of insertion sequence IS1236 were indicated by hybridization. Several of these copies were concentrated in one region of the chromosome in which a spontaneous deletion of approximately 100 kbp occurred. Moreover, contrary to previous reports, ColE1-based plasmids appeared to replicate autonomously in Acinetobacter sp. ADP1.

Acinetobacter↗
PubMed1976

Acinetobacter and similar organisms in ear infections.

Fifty-seven strains of acinetobacter-like organisms were isolated over a period of 26 months from the ears of 55 patients with acute or chronic otitis media, or otitis externa, and one strain was isolated in a survey of 50 normal ears. After comparison with eight reference strains, 32 of the isolates were identified as Acinetobacter anitratus, 22 as Acinetobacter Iwoffii, three as Moraxella spp. and one as Achromobacter sp. Analysis of the clinical findings suggests that although most of these organisms played little part in the disease process, a few strains were probably pathogenic in this situation.

Acinetobacter↗
PubMed1992

Analysis of polar lipids from some representative enterobacteria, Plesiomonas and Acinetobacter by fast atom bombardment-mass spectrometry.

Fast atom bombardment-mass spectrometry (FAB-MS) was used to analyse lipid extracts of bacteria to assess its usefulness for analysing anionic phospholipids of potential chemotaxonomic value. The following micro-organisms were tested: Acinetobacter calcoaceticus, Acinetobacter sp., Citrobacter freundii, Enterobacter cloacae (2 strains), Escherichia coli (3 strains), Hafnia alvei, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Plesiomonas shigelloides, Proteus mirabilis (3 strains), Serratia liquefaciens and Serratia marcescens. Negative-ion spectra provide data for twenty-seven major carboxylate anions (m/z 209-325) and for thirty-seven major phospholipid anions (m/z 645-774). Generally, the largest carboxylate peaks were due to 16:1, 16:0, cyc17 and 18:1 while the largest phospholipid anion peaks were due to PE(32:1), PE(33:1), PE(34:1), PE(34:2), PG(30:2), PG(31:2), PG(32:2), PG(34:1) and PS(33:0). However, quantitative differences were observed. For example, Acinetobacter lacked PE (33:1) but had exceptionally high peaks at m/z 748, PS(33:0), and m/z 281, octadecanoate. Unknown 'carboxylate' peaks were detected at m/z 254, 256, 261, 268, 282 and 301. In some cases, unknown peaks appeared to constitute possible homologous series being separated by delta m/z of 14(identical to methylene). For chemotaxonomic purposes, the complexity of the data required numerical analysis. Using the Pearson coefficient of linear correlation, as a measure of association, it was possible to compare all strains analysed. Typical results for strain comparisons were as follows: Ent. cloacae vs Ent. cloacae, r = 0.90 (Ent. cloacae vs Ac. calcoaceticus, r = 0.46). Thus FAB-MS represents an excellent means of obtaining large quantities of data on polar lipids of a range of bacterial isolates, which may be suitable for chemotaxonomic purposes.

Acinetobacter↗
PubMed1976

The purification and properties of cyclohexanone oxygenase from Nocardia globerula CL1 and Acinetobacter NCIB 9871.

1. Cyclohexanone oxygenases from Norcardia globerula CL1 and Acinetobacter NCIB 9871 have been purified 12-fold and 35-fold respectively and each gives a single symmetrical sedimentation peak in the ultracentrifuge and a single protein band on 2.25 nm average pore radius polyacrylamide gels. 2. The enzyme from N. globerula has a molecular weight of 53000 while that from Acinetobacter has a molecular weight of about 59000. Each is a single polypeptide chain with one mole of bound FAD per mole of protein that does not dissociate during purification. Acidification of the Acinetobacter enzyme in the presence of (NH4)2SO4 releases the bound FAD and yields native apoenzyme from which the active holoenzyme can be reconstituted. The apparent dissociation constant for the FAD is 40 nM.

Acinetobacter↗
PubMed1998

Comparison of ARDRA and recA-RFLP analysis for genomic species identification of Acinetobacter spp.

The genus Acinetobacter is subdivided into genospecies on the basis of DNA relatedness of strains. Phenotypic tests are insufficient to identify the genospecies to which an isolate belongs. The effectiveness of two previously described PCR-based methods for genospeciating Acinetobacter spp. was compared using a group of 32 well-characterised strains representing six genospecies. Amplified ribosomal DNA restriction analysis (ARDRA) correctly identified all 32 strains. Using restriction fragment length polymorphism (RFLP) of recA PCR amplimers, only six of the 32 strains were correctly identified. Heterogeneity in the recA gene sequence was demonstrated within five of the genospecies. ARDRA proved to be a reliable method whereas analysis of recA RFLP profiles did not enable the genospecies of most of the isolates of Acinetobacter spp. to be determined.

Acinetobacter↗
PubMed1994

Detection of aac(6')-I genes in amikacin-resistant Acinetobacter spp. by PCR.

The distribution of aac(6')-I genes in 62 strains of Acinetobacter spp. resistant to amikacin, netilmicin, and tobramycin and susceptible to gentamicin, a phenotype compatible with synthesis of an AAC(6')-I enzyme, was studied by PCR and by DNA hybridization. Both methods gave similar results. Among the 51 Acinetobacter baumannii strains, aac(6')-Ib was found in 19 isolates and aac(6')-Ih was found in the remaining strains. The aac(6')-Ig gene was present in all 10 A. haemolyticus strains studied and was detected only in this species. A pair of degenerate oligonucleotides complementary to conserved regions of aac(6')-Ic, -Id, -If, -Ig, and -Ih enabled detection of these genes and also of aac(6')-Ij, recently recognized in Acinetobacter sp. strain 13.

Acinetobacter↗
PubMed1997

Loss of intrinsic aminoglycoside resistance in Acinetobacter haemolyticus as a result of three distinct types of alterations in the aac(6')-Ig gene, including insertion of IS17.

The distribution of the aac(6')-Ig gene, encoding aminoglycoside 6'-N-acetyltransferase-Ig [AAC(6')-Ig], was studied in 96 Acinetobacter haemolyticus strains and 12 proteolytic Acinetobacter strains, including Acinetobacter genomospecies 6, 13, and 14 and 3 unnamed species assigned to this genomic group by DNA-DNA hybridization. This gene was detected by DNA-DNA hybridization in all 96 A. haemolyticus strains and by PCR in 95 strains but was not detected in strains of other species, indicating that it may be used to identify A. haemolyticus. Three A. haemolyticus strains were susceptible to tobramycin and did not produce an aminoglycoside 6'-N-acetylating activity, although they contained aac(6')-Ig-related sequences. An analysis of three susceptible A. haemolyticus strains indicated that aminoglycoside resistance was abolished by the following three distinct mechanisms: (i) a point mutation in aac(6')-Ig that led to a Met56-->Arg substitution, which was shown by analysis of a revertant to be responsible for the loss of resistance; (ii) a polythymine insertion that altered the reading frame; and (iii) insertion of IS17, a new member of the IS903 family. These observations indicated that AAC(6')-Ig is not essential for the viability of A. haemolyticus, although the aac(6')-Ig gene was detected in all members of this species.

Acetyltransferases↗
PubMed2005

Novel acquired metallo-beta-lactamase gene, bla(SIM-1), in a class 1 integron from Acinetobacter baumannii clinical isolates from Korea.

Carbapenem resistance mediated by acquired carbapenemase genes has been increasingly reported, particularly for clinical isolates of Pseudomonas aeruginosa and Acinetobacter spp. Of 1,234 non-duplicate isolates of carbapenem-resistant Pseudomonas spp. and Acinetobacter spp. isolated at a tertiary-care hospital in Seoul, Korea, 211 (17%) were positive for metallo-beta-lactamase (MBL). Of these, 204 (96%) had either the bla(IMP-1) or bla(VIM-2) allele. In addition, seven Acinetobacter baumannii isolates were found to have a novel MBL gene, which was designated bla(SIM-1). The SIM-1 protein has a pI of 7.2, is a new member of subclass B1, and exhibits 64 to 69% identity with the IMP-type MBLs, which are its closest relatives. All SIM-1-producing isolates exhibited relatively low imipenem and meropenem MICs (8 to 16 microg/ml) and had a multidrug resistance phenotype. Expression of the cloned bla(SIM-1) gene in Escherichia coli revealed that the encoded enzyme is capable of hydrolyzing a broad array of beta-lactams, including penicillins, narrow- to expanded-spectrum cephalosporins, and carbapenems. The bla(SIM-1) gene was carried on a gene cassette inserted into a class 1 integron, which included three additional cassettes (arr-3, catB3, and aadA1). The strains were isolated from sputum and urine specimens from patients with pneumonia and urinary tract infections, respectively. All patients had various underlying diseases. Pulsed-field gel electrophoresis of SmaI-digested genomic DNAs showed that the strains belonged to two different clonal lineages, indicating that horizontal transfer of this gene had occurred and suggesting the possibility of further spread of resistance in the future.

Acinetobacter baumannii↗
PubMed2006

Occurrence of OXA-58-like carbapenemases in Acinetobacter spp. collected over 10 years in three continents.

OXA-58 is a recently described carbapenemase from Acinetobacter spp. in Europe. We examined earlier worldwide Acinetobacter collections and found bla(OXA-58) in 30 carbapenem-nonsusceptible isolates, including several isolates collected in Argentina and Kuwait in 1995 and 1996 and in a British outbreak strain from 2000. Most isolates (28 of 30) also had bla(OXA-51). We conclude that bla(OXA-58) is geographically widespread and has occurred in Acinetobacter spp. for over 10 years.

Acinetobacter↗
PubMed1980

Thermal inactivation and injury of Moraxella-Acinetobacter cells in ground beef.

The thermal inactivation and injury (sensitivity to 0.8% NaCl) of a radiation-resistant culture of Moraxella-Acinetobacter mixed in minced beef were determined. Survival curves for Moraxella-Acinetobacter cells in beef had an initial shoulder preceding a logarithmic decline when the cells were heated at 65, 70, and 75 degrees C, but not at 80 degrees C. In all cases, the experimental points not included in the shoulder were linearized by means of a least-squares straight line, and the latter was used to determine D values. Shoulder values of 12.2, 4.1, and 0.6 min at temperatures of 65, 70, and 75 degrees C were added to the respective D values of 35.4, 6.6, and 1.4 min to determine the time required to destroy one log cycle. The Z value was 7.3 degrees C. Moraxella-Acinetobacter cells in meat were more rapidly injured than inactivated, on initial exposure to heat. The number of cells injured by this initial exposure increased as the temperature was increased. At 65 degrees C the percentage of injured cells increased more rapidly with exposure time than did the inactivated cells. As the temperature was increased, the rates of inactivation and injury became more and more similar.

Acinetobacter↗
PubMed1986

Evolved aniline catabolism in Acinetobacter calcoaceticus during continuous culture of river water.

Adaptation of Acinetobacter calcoaceticus from river water to aniline depends on the dynamics of parent and mutant populations. The parent, Acinetobacter strain DON26 phenotype Ani0, was common in river water and assimilated aniline effectively at micromolar concentrations, but was inhibited at higher concentrations of aniline. The Ani0 phenotype was also characterized by a broad specificity for oxidation of chloroanilines by aniline-induced cells. The mutant Ani+ phenotype was represented by DON2, isolated from a population of less than 100 cells ml-1 in a mixed river water culture, and by DON261, isolated during continuous culture of DON26. Ani+ strains assimilated aniline at a greater maximum specific rate than the parent and were able to grow at concentrations of aniline greater than 16 mM. These strains cooxidized phenol after growth at high aniline concentrations, but showed reduced activity toward chloroanilines. These changes plus kinetic data, oxygen uptake data, and the results of auxanography indicate that the mutant has an increased activity and altered specificity of the initial enzyme in the aniline catabolic pathway. The parent strain, DON26, was at a selective advantage relative to the mutant at low concentrations of aniline, but was replaced by the mutant when aniline concentrations increased. Adaptation of the mixed river water community to aniline involved selection of both phenotypes. Reversion of the Ani+ to Ani0 phenotype occurred at a frequency of 10(-2) in the absence of aniline selection. Plasmid content was not altered during either acquisition or loss of the Ani+ phenotype. Adaptive changes in Acinetobacter spp. populations illustrate important differences in the catabolic activities of natural and pollutant selected strains.(ABSTRACT TRUNCATED AT 250 WORDS)

Acinetobacter↗