PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Acinetobacter Infections”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 307 records · Page 17Linked to original sources
PubMed2006

Heteroresistance to colistin in multidrug-resistant Acinetobacter baumannii.

Multidrug-resistant Acinetobacter baumannii has emerged as a significant clinical problem worldwide and colistin is being used increasingly as "salvage" therapy. MICs of colistin against A. baumannii indicate its significant activity. However, resistance to colistin in A. baumannii has been reported recently. Clonotypes of 16 clinical A. baumannii isolates and ATCC 19606 were determined by pulsed-field gel electrophoresis (PFGE), and colistin MICs were measured. The time-kill kinetics of colistin against A. baumannii ATCC 19606 and clinical isolate 6 were investigated, and population analysis profiles (PAPs) were conducted. Resistance development was investigated by serial passaging with or without exposure to colistin. Five different PFGE banding patterns were found in the clinical isolates. MICs of colistin against all isolates were within 0.25 to 2 microg/ml. Colistin showed early concentration-dependent killing, but bacterial regrowth was observed at 24 h. PAPs revealed that heteroresistance to colistin occurred in 15 of the 16 clinical isolates. Subpopulations (<0.1% from inocula of 10(8) to 10(9) CFU/ml) of ATCC 19606, and most clinical isolates grew in the presence of colistin 3 to 10 microg/ml. Four successive passages of ATCC 19606 in broth containing colistin (up to 200 microg/ml) substantially increased the proportion of the resistant subpopulations able to grow in the presence of colistin at 10 microg/ml from 0.000023 to 100%; even after 16 passages in colistin-free broth, the proportion only decreased to 2.1%. This represents the first demonstration of heterogeneous colistin-resistant A. baumannii in "colistin-susceptible" clinical isolates. Our findings give a strong warning that colistin-resistant A. baumannii may be observed more frequently due to potential suboptimal dosage regimens recommended in the product information of some products of colistin methanesulfonate.

Acinetobacter Infections↗
PubMed2002

Molecular characterization of integrons in epidemiologically unrelated clinical isolates of Acinetobacter baumannii from Italian hospitals reveals a limited diversity of gene cassette arrays.

Integron carriage by 36 epidemiologically unrelated Acinetobacter baumannii isolates collected over an 11-year period from patients in six different Italian hospitals was investigated. Sixteen type 1 integron-positive isolates (44%) were found, 13 of which carried the same array of cassettes, i.e., aacC1, orfX, orfX', and aadA1a. As ribotype analysis of the isolates demonstrated a notable genetic diversity, horizontal transfer of the entire integron structure or ancient acquisition was hypothesized.

Acinetobacter Infections↗
PubMed2006

Occurrence of carbapenem-resistant Acinetobacter baumannii clones at multiple hospitals in London and Southeast England.

From late 2003 to the end of 2005, the Health Protection Agency's national reference laboratories received approximately 1,600 referrals of Acinetobacter spp., including 419 and 58 examples, respectively, of two carbapenem-resistant Acinetobacter baumannii lineages, designated OXA-23 clones 1 and 2. Representatives of these clones were obtained from 40 and 8 hospitals, respectively, in London or elsewhere in Southeast England. Both clones had blaOXA-23-like genes, as well as the intrinsic (but downregulated) blaOXA-51-like carbapenemase genes typical of A. baumannii. Both were highly multiresistant: only colistin and tigecycline remained active versus OXA-23 clone 1 isolates; OXA-23 clone 2 isolates were also susceptible to amikacin and minocycline. These lineages increase the burden created by the southeast (SE) clone, a previously reported A. baumannii lineage with variable carbapenem resistance contingent on upregulation of the blaOXA-51-like gene. Known since 2000, the SE clone had been referred from over 40 hospitals by the end of 2005, with 627 representatives received by the reference laboratories. The OXA-23 clone 2 is now in decline, but OXA-23 clone 1 continues to be referred from new sites, as does the SE clone. Their spread is forcing the use of unorthodox therapies, principally colistin and tigecycline, although the optimal regimens remain uncertain.

Acinetobacter Infections↗
PubMed2006

Horizontal gene transfer in a polyclonal outbreak of carbapenem-resistant Acinetobacter baumannii.

In the last few years, phenotypically carbapenem resistant Acinetobacter strains have been identified throughout the world, including in many of the hospitals and intensive care units (ICUs) of Australia. Genotyping of Australian ICU outbreak-associated isolates by pulsed-field gel electrophoresis of whole genomic DNA indicated that different strains were cocirculating within one hospital. The carbapenem-resistant phenotype of these and other Australian isolates was found to be due to carbapenem-hydrolyzing activity associated with the presence of the blaOXA-23 gene. In all resistant strains examined, the blaOXA-23 gene was adjacent to the insertion sequence ISAba1 in a structure that has been found in Acinetobacter baumannii strains of a similar phenotype from around the world; blaOXA-51-like genes were also found in all A. baumannii strains but were not consistently associated with ISAba1, which is believed to provide the promoter required for expression of linked antibiotic resistance genes. Most isolates were also found to contain additional antibiotic resistance genes within the cassette arrays of class 1 integrons. The same cassette arrays, in addition to the ISAba1-blaOXA-23 structure, were found within unrelated strains, but no common plasmid carrying these accessory genetic elements could be identified. It therefore appears that antibiotic resistance genes are readily exchanged between cocirculating strains in epidemics of phenotypically indistinguishable organisms. Epidemiological investigation of major outbreaks should include whole-genome typing as well as analysis of potentially transmissible resistance genes and their vehicles.

Acinetobacter Infections↗
PubMed2002

Endemic carbapenem resistance associated with OXA-40 carbapenemase among Acinetobacter baumannii isolates from a hospital in northern Spain.

Eighty-two carbapenem-resistant isolates of Acinetobacter baumannii from a single hospital in Bilbao were typed into two major clusters and several subclusters. Disk synergy tests and PCR indicated the production of a zinc-independent OXA-class carbapenemase. Sequencing identified this enzyme, OXA-40, as a variant of the OXA-24-OXA-25-OXA-26 cluster.

Acinetobacter Infections↗
PubMed2002

Loss of a 29-kilodalton outer membrane protein in Acinetobacter baumannii is associated with imipenem resistance.

We analyzed the possible causes of imipenem (IPM) resistance in multidrug-resistant isolates of Acinetobacter baumannii. Comparison of the outer membrane protein (OMP) profiles of two genomically related strains (Ab288 [IPM sensitive] and Ab242 [IPM resistant]) indicated the conspicuous loss of a 29-kDa polypeptide in the Ab242 strain. No carbapenemase activity was detected in any of these strains. The treatment of Ab288 with sodium salicylate resulted in IPM resistance and the loss of the 29-kDa OMP. In addition, IPM-resistant clones of Ab288 which were selected by repetitive culturing in increasing concentrations of this antibiotic also showed the absence of this 29-kDa OMP.

Acinetobacter Infections↗
PubMed2003

Outbreak of carbapenem-resistant Acinetobacter baumannii producing the OXA-23 enzyme in Curitiba, Brazil.

Carbapenem-resistant Acinetobacter baumannii isolates were obtained from eight patients in two hospitals in Curitiba, Brazil. The isolates were multiresistant, belonged to a single strain, and produced the OXA-23 carbapenemase. Treatment options were limited, although the isolates were susceptible to polymyxin B in vitro. The strain contributed to the deaths of five patients.

Acinetobacter Infections↗
PubMed2005

Sequence-based typing of ade B as a potential tool to identify intraspecific groups among clinical strains of multidrug-resistant Acinetobacter baumannii.

Sequence analysis of an 850-bp fragment internal to the aspecific drug efflux gene ade B revealed 11 sequence types (STs) among a collection of 50 multidrug-resistant Acinetobacter baumannii (MDRAB) strains, including members of pan-European clones I, II, and III. The delineation of STs conformed with the intraspecific grouping of these strains previously determined by different DNA fingerprinting methods. Larger strain collections need to be screened to further explore the potential of sequence-based ade B typing as a universal tool for the monitoring of MDRAB clones.

Acinetobacter Infections↗
PubMed2005

Reliability of the E-test method for detection of colistin resistance in clinical isolates of Acinetobacter baumannii.

We compared the E-test to the broth microdilution method for testing the susceptibility of 115 clinical isolates of Acinetobacter baumannii to colistin. Twenty-two (19.1%) strains were resistant to colistin and 93 (80.8%) strains were susceptible according to the reference broth microdilution method. A categorical agreement of 98.2% was found, with only two (1.7%) very major errors. Agreement within 1 twofold dilution between the E-test and the broth microdilution was 16.5%. Complete agreement was found for the strains for which MICs fell within the range of 0.25 to 1 microg of colistin/ml. However, there was poor concordance, particularly in extreme dilutions with higher MICs by the E-test method.

Acinetobacter Infections↗
PubMed2005

Detection and typing of integrons in epidemic strains of Acinetobacter baumannii found in the United Kingdom.

Integrons were sought in Acinetobacter isolates from hospitals in the United Kingdom by integrase gene PCR. Isolates were compared by pulsed-field gel electrophoresis, and most belonged to a small number of outbreak strains or clones of A. baumannii, which are highly successful in the United Kingdom. Class 1 integrons were found in all of the outbreak isolates but in none of the sporadic isolates. No class 2 integrons were found. Three integrons were identified among the main outbreak strains and clones. While a particular integron was usually associated with a strain or clone, some members carried a different integron. Some integrons were associated with more than one strain. The cassette arrays of two of the integrons were very similar, both containing gene aacC1, which confers resistance to gentamicin, two open reading frames coding for unknown products (orfX, orfX'), and gene aadA1a, which confers resistance to spectinomycin and streptomycin. The larger of these integrons had two copies of the first (orfX) of the gene cassettes coding for unknown products. The third integron, with a cassette array containing gene aacA4, which codes for amikacin, netilmicin, and tobramycin resistance; a chloramphenicol acetyltransferase, catB8; and gene aadA1, conferring resistance to spectinomycin and streptomycin, was associated with an OXA-23 carbapenemase-producing clone, which has spread rapidly in hospitals in the United Kingdom during 2003 and 2004. These integron cassette arrays have been found in other outbreak strains of A. baumannii from other countries. We conclude that integrons are useful markers for epidemic strains of A. baumannii and that integron typing provides valuable information for epidemiological studies.

Acinetobacter Infections↗
PubMed2005

Standardization and interlaboratory reproducibility assessment of pulsed-field gel electrophoresis-generated fingerprints of Acinetobacter baumannii.

A standard procedure for pulsed-field gel electrophoresis (PFGE) of macrorestriction fragments of Acinetobacter baumannii was set up and validated for its interlaboratory reproducibility and its potential for use in the construction of an Internet-based database for international monitoring of epidemic strains. The PFGE fingerprints of strains were generated at three different laboratories with ApaI as the restriction enzyme and by a rigorously standardized procedure. The results were analyzed at the respective laboratories and also centrally at a national reference institute. In the first phase of the study, 20 A. baumannii strains, including 3 isolates each from three well-characterized hospital outbreaks and 11 sporadic strains, were distributed blindly to the participating laboratories. The local groupings of the isolates in each participating laboratory were identical and allowed the identification of the epidemiologically related isolates as belonging to three clusters and identified all unrelated strains as distinct. Central pattern analysis by using the band-based Dice coefficient and the unweighted pair group method with mathematical averaging as the clustering algorithm showed 95% matching of the outbreak strains processed at each local laboratory and 87% matching of the corresponding strains if they were processed at different laboratories. In the second phase of the study, 30 A. baumannii isolates representing 10 hospital outbreaks from different parts of Europe (3 isolates per outbreak) were blindly distributed to the three laboratories, so that each laboratory investigated 10 epidemiologically independent outbreak isolates. Central computer-assisted cluster analysis correctly identified the isolates according to their corresponding outbreak at an 87% clustering threshold. In conclusion, the standard procedure enabled us to generate PFGE fingerprints of epidemiologically related A. baumannii strains at different locations with sufficient interlaboratory reproducibility to set up an electronic database to monitor the geographic spread of epidemic strains.

Acinetobacter Infections↗
PubMed2005

Development of a multilocus sequence typing scheme for characterization of clinical isolates of Acinetobacter baumannii.

In this study a multilocus sequence typing (MLST) scheme for Acinetobacter baumannii was developed and evaluated by using 40 clinical A. baumannii isolates recovered from outbreaks in Spanish and German hospitals during the years 1990 to 2001, as well as isolates from other European hospitals and two DSMZ reference strains of A. baumannii. For comparison, two isolates of Acinetobacter species 13 (sensu Tjernberg and Ursing), two clinical isolates, and three DSMZ strains of A. calcoaceticus (both belonging to the A. calcoaceticus-A. baumannii complex) were also investigated. Primers were designed for conserved regions of housekeeping genes, and 305- to 513-bp internal fragments of seven such genes-gltA, gyrB, gdhB, recA, cpn60, gpi, and rpoD-were sequenced for all strains. The number of alleles at individual loci ranged from 6 to 12, and a total of 20 allelic profiles or sequence types were distinguished among the investigated A. baumannii strains. The MLST data were in high concordance with the epidemiologic typing results generated by pulsed-field gel electrophoresis and amplified fragment length polymorphism fingerprinting. The MLST scheme provides a high level of resolution and an excellent tool for studying the population structure and long-term epidemiology of A. baumannii.

Acinetobacter Infections↗
PubMed2005

Outbreak of carbapenem-resistant Acinetobacter baumannii producing the carbapenemase OXA-23 in a tertiary care hospital of Papeete, French Polynesia.

Carbapenem-resistant Acinetobacter baumannii isolates were obtained from 24 patients between March and May 2004 at the Centre Hospitalier de Polynésie Française, Tahiti, French Polynesia. The isolates were multidrug resistant, produced the carbapenemase OXA-23, and belonged to a single clone presenting several subtypes, suggesting an endemic situation. This study further illustrates the global spread of this kind of beta-lactamase-mediated resistance.

Acinetobacter Infections↗
PubMedDate not supplied

Cardiac catheterization complicated by iliacus abscess: a rare complication of transfemoral approach--a case report.

Iliacus abscess is an extremely rare complication of percutaneous transfemoral artery catheterization. This is a report of a case of iliacus abscess and Acinetobacter baumanii sepsis following percutaneous transfemoral artery catheterization. After a 43-day course of intravenous antibiotics treatment and repeated drainage, clinical recovery was achieved, though without complete radiologic resolution.

Abscess↗
PubMed2006

Post-neurosurgical meningitis due to multidrug-resistant Acinetobacter baumanii treated with intrathecal colistin: case report and review of the literature.

Intrathecal colistin (Polymxin E) is becoming an important option for the treatment of post-neurosurgical meningitis caused by multidrug resistant (MDR) Acinetobacter baumannii. We report a case of 28-year-old man who developed meningitis due to MDR A. baumannii associated with an external ventricular drain. The patient was cured using a 4-week course of intrathecal colistin 3.2 mg via external ventricular drain (EVD) daily without any serious side effects.

Acinetobacter Infections↗