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PubMedDate not supplied

Acinetobacter calcoaceticus sepsis in children with malignancies.

The clinical and microbiologic characteristics of 29 episodes of sepsis caused by Acinetobacter calcoaceticus were reviewed in 25 children with underlying malignancies. Of the 29 episodes of sepsis with this organism 28 occurred from 1980 through 1984, compared with 1 episode from 1973 to 1979. Risk of infection was associated with the presence of intravascular cannulae, osteosarcoma and recent administration of antitumor chemotherapy. There was no association with neutropenia, malnutrition or focal infection. Of 28 organisms for which the biotypes were known, 14 (50%) were var. lwoffi and 14 (50%) were var. anitratus; 11 episodes (38%) were part of a polymicrobial bacteremia. All patients responded favorably to antimicrobial therapy.

Acinetobacter↗
PubMed2004

Acinetobacter baumanii meningitis: a rare complication of incidental durotomy.

Despite the frequency of dural tears in spinal surgery, meningitis is a rare complication reported to occur with a frequency of 0.18%. To the best of our knowledge, no case of Acinetobacter baumanii meningitis has been reported in the literature after a dural tear secondary to lumbar spine discectomy. This case highlights the importance of repairing all dural tears and commencing antibiotics that cover uncommon bacteria in those who develop symptoms of meningitis in this setting.

Acinetobacter Infections↗
PubMed2003

Clinical impact of pneumonia caused by Acinetobacter baumannii in intubated patients: a matched cohort study.

OBJECTIVE: To determine whether ventilator-associated pneumonia caused by Acinetobacter baumannii (VAPAB) is associated with increased mortality rate. DESIGN: A retrospective matched case-control study in which all intensive care unit adult patients with microbiologically documented VAPAB were defined as cases. SETTING: Four intensive care units from teaching hospitals. PATIENTS: Sixty patients were matched to sixty controls. MEASUREMENTS AND MAIN RESULTS: Controls were matched based on stay before pneumonia onset, disease severity (Acute Physiology and Chronic Health Evaluation II) at admission, and diagnostic category. Population characteristics and intensive care unit mortality rates of patients with VAPAB and their controls were compared. Attributable mortality was determined by subtracting the crude mortality rate of the controls from the crude mortality rate of the case patients. Twenty-four of the 60 case patients died, representing a crude mortality rate of 40%, whereas 17 of the 60 controls died, a crude mortality rate of 28.3% (p =.17). Crude intensive care unit mortality was the same (12 of 35, 34.2%) in patients with VAPAB caused by strains sensitive to imipenem and in their matched controls. It was 44% for the 25 patients with imipenem-resistant strains with an estimated attributable mortality rate of 20.0% (95% confidence interval, -5.6% to 45.7%). Mean intensive care unit stay of patients and controls was 35.3 and 36.6 days, respectively (p = nonsignificant). CONCLUSION: In intubated patients, pneumonia by A. baumannii is not significantly associated with attributable mortality rate or an increased length of intensive care unit stay.

Acinetobacter Infections↗
PubMed2005

Update on Pseudomonas aeruginosa and Acinetobacter baumannii infections in the healthcare setting.

PURPOSE OF REVIEW: Infections with Pseudomonas aeruginosa and Acinetobacter baumannii are of great concern for hospitalized patients, especially with multidrug-resistant strains. This review focuses on recent data that may help us to understand the emergence, spread, and persistence of antibiotic resistance, and summarizes the optional treatment feasible for these resistant bacteria. RECENT FINDINGS: Multidrug-resistant P. aeruginosa and A. baumannii are increasingly causing nosocomial infections; multidrug-resistant clones are spreading into new geographic areas, and susceptible strains are acquiring resistance genes. New extended-spectrum beta-lactamases and carbapenemases are emerging, leading to pan-resistant strains. Current studies focus on the effect of antibiotics on gene expression in P. aeruginosa biofilms and their contribution to resistance to therapy. Treatment options for multidrug-resistant P. aeruginosa and A. baumannii infections are limited in most cases to carbapenems. Sulbactam is a treatment option for pan-resistant A. baumannii, and or renewed use of an old drug, colistin, is being entertained for pan-resistant A. baumannii and P. aeruginosa. Immunotherapy is a promising new modality being explored. Prevention of emergence of resistance through combination therapy and pharmacokinetic strategies are studied. SUMMARY: The emergence and spread of multidrug-resistant P. aeruginosa and A. baumannii and their genetic potential to carry and transfer diverse antibiotic resistance determinants pose a major threat in hospitals. The complex interplay of clonal spread, persistence, transfer of resistance elements, and cell-cell interaction contribute to the difficulty in treating infections caused by these multidrug-resistant strains. In the absence of new antibiotic agents, new modalities of treatment should be developed.

Acinetobacter Infections↗
PubMed2003

Thyroid abscess due to Acinetobacter calcoaceticus: case report and review of the causes of and current management strategies for thyroid abscesses.

Thyroid abscess was a common condition in the era before antibiotics. In the current medical environment, however, it is a clinical entity that is seldom encountered. We report the case of a unique cause of thyroid abscess, the environmental Gram-negative bacterium Acinetobacter calcoaceticus. Review of the published causes of thyroid abscess since 1980 demonstrated that although Gram-positive bacteria (Staphylococcus and Streptococcus species) remain the most common causes, there has been a marked decrease in the number of cases caused by mycobacteria, Salmonella species, and anaerobes when compared with the early part of the 20th century. Patients infected with the human immunodeficiency virus, however, still develop mycobacterial and fungal thyroid infections with some regularity. Reported modes of management of thyroid abscess vary, but drainage remains an integral component of therapy for resolution of the infection.

AIDS-Related Opportunistic Infections↗
PubMed2001

Acinetobacter baumannii has two genes encoding glutathione-dependent formaldehyde dehydrogenase: evidence for differential regulation in response to iron.

The adhC1 gene from Acinetobacter baumannii 8399, which encodes a glutathione-dependent formaldehyde dehydrogenase (GSH-FDH), was identified and cloned after mapping the insertion site of Tn3-HoHo1 in a recombinant cosmid isolated from a gene library. Sequence analysis showed that this gene encodes a protein exhibiting significant similarity to alcohol dehydrogenases in bacterial, yeast, plant and animal cells. The expression of the adhC1 gene was confirmed by the detection of GSH-FDH enzyme activity in A. baumannii and Escherichia coli cells that expressed the cloned gene. However, the construction and analysis of an A. baumannii 8399 adhC1::Tn3-HoHo1 isogenic derivative revealed the presence of adhC2, a second copy of the gene encoding GSH-FDH activity. Enzyme assays and immunoblot analysis showed that adhC2 encodes a 46.5 kDa protein that is produced in similar amounts under iron-rich and iron-limited conditions. In contrast, the expression of adhC1, which encodes a 45 kDa protein with GSH-FDH activity, is induced under iron limitation and repressed when the cells are cultured in the presence of free inorganic iron. The differential expression of adhC1 is controlled at the transcriptional level and mediated through the Fur iron-repressor protein, which has potential binding sites within the promoter region of this adhC copy. The expression of both adhC copies is significantly enhanced by the presence of sub-inhibitory concentrations of formaldehyde in the culture media. Examination of different A. baumannii isolates indicates that they can be divided into two groups based on the type of GSH-FDH they produce. One group contains only the constitutively expressed 46.5 kDa protein, whilst the other produces this GSH-FDH type in addition to the iron-regulated isoenzyme. Further analysis showed that the presence and expression of the two adhC genes does not confer resistance to exogenous formaldehyde, nor does it enable it to utilize methylated compounds as a sole carbon source when cultured under iron-rich as well as iron-deficient conditions.

Acinetobacter↗
PubMed1984

Fingerprinting Acinetobacter strains from clinical sources by numerical analysis of electrophoretic protein patterns.

A total of 57 strains of Acinetobacter calcoaceticus was fingerprinted by SDS-PAGE of cellular protein. All strains were also examined by conventional, API and N/F-Tek methods, and antibiotic sensitivity patterns were determined. In general, using the API 20E and N/F-Tek methods, it was possible to assign isolates of A. calcoaceticus to the two accepted "biotypes" or "varieties", A.c. anitratus and A.c. lwoffi, but these methods did not offer useful subdivision of the biotypes. Gel electrophoresis permitted subdivision of the strains into clusters in a manner which suggests that the technique may be valuable in typing strains isolated during outbreaks of infection in hospital.

Acinetobacter↗
PubMed1987

Cell envelope protein profiles of Acinetobacter calcoaceticus strains isolated in hospitals.

The cell envelope protein patterns of 78 strains of Acinetobacter calcoaceticus, mainly isolated in hospitals, were analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The patterns were stable and reproducible. Comparison of the protein profiles made possible differentiation between two groups of strains. The patterns of the first group could be classified on the basis of concordance. Some profiles appeared to be associated with the epidemiological origin of the strains. The second group consisted of strains with unique patterns which could not be classified. Comparison of SDS-PAGE patterns appears to be a suitable method for the relative classification of A. calcoaceticus strains of nosocomial origin.

Acinetobacter↗
PubMed1991

Immune response to Acinetobacter calcoaceticus infection in man.

After growth in an iron-depleted chemically-defined medium Acinetobacter calcoaceticus expressed four high mol. wt outer-membrane proteins (OMPs) which were repressed under iron supplementation or in a complex laboratory medium. Immunoblotting with serum from a septicaemic patient infected with A. calcoaceticus revealed antibody binding to these iron-repressible OMPs, indicating that they were expressed in vivo, and also to the 42- and 18-Kda OMPs. Although the antibody response to the OMPs did not vary significantly during convalescence, the response to the O-polysaccharide component of lipopolysaccharide decreased significantly. However, antibodies in serum from patients with A. calcoaceticus wound infections reacted with the iron repressible OMPs and a 54-Kda antigen suggesting a difference in immune recognition between local and systemic infection.

Acinetobacter↗
PubMed1994

A comparative study of ribotyping and arbitrarily primed polymerase chain reaction for investigation of hospital outbreaks of Acinetobacter baumannii infection.

Arbitrarily primed polymerase chain reaction (AP-PCR) and ribotyping were compared in an investigation of an outbreak of Acinetobacter baumannii infections. Twenty-five clinical isolates shown previously by other criteria to belong to two different groups, and nine randomly selected A. baumannii clinical isolates from other hospitals were investigated. Among the strains analysed, nine different EcoRI rRNA gene restriction pattern fingerprints were observed. While similarity was detected between strains of the same group, these fingerprints differed clearly between the two A. baumannii groups defined in the outbreak. Two of the nine strains selected randomly had the same ribotype as those strains involved in the outbreak, whereas the remaining seven strains each had a different ribotype. When the strains were tested by AP-PCR with 0.25, 0.5 or 1 microM of M13 forward primer, 10 different profiles were obtained. However, 11 profiles were observed if two different primer concentrations (0.25 and 1 microM) were used. It was concluded that ribotyping and AP-PCR exhibited a similar discriminatory power, although AP-PCR had the additional advantages of speed and simplicity.

Acinetobacter↗
PubMed1995

Correlation of six methods for typing nosocomial isolates of Acinetobacter baumannii.

A comparative study of biotyping, antimicrobial susceptibility, whole-cell protein analysis, plasmid analysis, pulsed-field gel electrophoresis of chromosomal DNA and polymerase chain reaction with arbitrary primers of Acinetobacter baumannii isolates from three large hospitals was performed to determine the best markers for epidemiological purposes. Ninety-two isolates were included: 38 belonged to a previously described outbreak and 54 were randomly selected from sporadic cases of infection. Biotyping, whole-cell protein and plasmid analysis were the least discriminatory methods, whereas antimicrobial susceptibility and polymerase chain reaction with arbitrary primers showed moderate discriminatory power. Typing based on pulsed-field gel electrophoresis of chromosomal DNA appeared to be the best discriminatory method (discrimination index of 0.9623). The addition of polymerase chain reaction with arbitrary primers or antimicrobial susceptibility to pulsed-field gel electrophoresis of chromosomal DNA did not further increase the discriminatory power.

Acinetobacter↗
PubMed1995

Automated laser fluorescence analysis of randomly amplified polymorphic DNA: a rapid method for investigating nosocomial transmission of Acinetobacter baumannii.

A rapid method for genotyping Acinetobacter baumannii based on PCR-fingerprinting with fluorescent primers was evaluated. Automated laser fluorescence analysis (ALFA) enabled on-line generation of high resolution DNA-fingerprints during polyacrylamide gel electrophoresis of randomly amplified polymorphic DNA (RAPD) products. The results were in concordance with macro-restriction fragment patterns produced by pulse-field gel electrophoresis (PFGE) of ApaI digests of chromosomal DNA. RAPD-ALFA was able to identify homologous strains suggestive of horizontal transmission in < 8 h after colonies were obtained on solid media, whereas PFGE analysis took c. 90 h. Speed and digitised data format renders RAPD-ALFA attractive for routine in-house epidemiological screening of isolates from intensive care and other hospital units.

Acinetobacter↗
PubMed1996

Comparison of rapid automated laser fluorescence analysis of DNA fingerprints with four other computer-assisted approaches for studying relationships between Acinetobacter baumannii isolates.

The relationships between isolates suggested by a novel DNA typing method (RAPD-ALFA) that combines randomly amplified polymorphic DNA with automated on-line laser fluorescence analysis of DNA fragments were compared with those suggested by four other computer-assisted typing strategies (biotyping, antibiogram typing, pulsed-field gel analysis of chromosomal fingerprints and arbitrarily-primed DNA amplification with three different primers) for 25 isolates of Acinetobacter baumannii obtained from 12 different hospitals in four countries over a period of 12 years. The results obtained by cluster analysis with two different software packages confirmed that the relationships suggested by RAPD-ALFA were robust and essentially similar to those suggested by the other more laborious computer-assisted typing methods. The technique of RAPD-ALFA appears to offer the possibility of routine on-line molecular identification and typing of isolates from particular hospital wards or units (e.g., intensive care units), and could, therefore, play a key role in the early recognition and prevention of outbreaks of infection.

Acinetobacter↗
PubMed1999

Some immunological properties of lipopolysaccharide from Acinetobacter baumannii.

Acinetobacter baumannii, mainly biotype 9, is an important nosocomial opportunist pathogen in Chile and other countries. The biological basis of its virulence and prevalence is still unknown. As lipopolysaccharide (LPS) is often associated with virulence, some biological properties of purified LPS from seven nosocomial isolates, comprising four isolates of A. baumannii biotype 9, two isolates of biotype 8 and one isolate of biotype 1, were investigated. LPS was extracted and purified from each isolate by the hot phenol-water method, and its ability to elicit a mitogenic response and to induce the synthesis of a tumour necrosis factor (TNF-alpha) in mouse spleen cells was determined. Activity was evaluated in vivo by determining the splenic index in comparison with LPS from Salmonella Typhimurium. All seven LPS samples were mitogenic on the basis of cellular proliferation experiments and six induced synthesis of TNF-alpha. Similar results were obtained in in-vivo experiments in which LPS induced spleen cell growth, as shown by determination of the splenic index. These results suggest that the LPS of A. baumannii might contribute to the pathogenic properties of this species.

Acinetobacter↗
PubMed2004

Long-term predominance of two pan-European clones among multi-resistant Acinetobacter baumannii strains in the Czech Republic.

In a recent study, a large proportion of multi-drug-resistant (MDR) Acinetobacter baumannii strains that were isolated from hospitalized patients in the Czech Republic was found to belong to two major groups (A and B). These groups appeared to be similar to epidemic clones I and II, respectively, which were identified previously among outbreak strains from north-western European hospitals. The aim of the present study was to assess in detail the genetic relatedness of Czech A. baumannii strains and those of epidemic clones I and II by using ribotyping with HindIII and HincII and by AFLP fingerprinting. The study collection included 70 MDR strains that were isolated in 30 Czech hospitals in 1991-2001, 15 susceptible Czech strains from 1991 to 1996 and 13 reference strains of clones I and II from 1982 to 1990. One major HindIII/HincIII ribotype (R1-1) was observed in 38 MDR Czech strains and eight reference strains of clone I, whereas another major ribotype (R2-2) was observed in 11 MDR Czech strains and in three reference strains of clone II. A selection of 59 Czech strains (representative of all ribotypes) and the 13 reference strains were investigated by AFLP fingerprinting. At a clustering level of 83%, two large clusters could be distinguished: cluster 1 included all reference strains of clone I and 25 MDR Czech strains, whilst cluster 2 contained all reference strains of clone II and 11 MDR Czech strains. There was a clear correlation between the groupings by AFLP analysis and by ribotyping, as all strains with ribotype R1-1 and four strains with slightly different ribotypes were found in AFLP cluster 1, whereas all strains with ribotype R2-2 and seven strains with similar ribotypes were in AFLP cluster 2. Thus, 41 and 21 MDR Czech strains could be classified as belonging to clones I and II, respectively. The remaining eight MDR and 15 susceptible strains were highly heterogeneous and were distinct from clones I and II by both AFLP fingerprinting and ribotyping. These results indicate that the two predominant groups observed among MDR Czech A. baumannii strains from the 1990s are genetically congruent with the north-western European epidemic clones that were found in the 1980s. Recognition of these clinically relevant, widespread clones is important in infection prevention and control; they are also interesting subjects to study genetic mechanisms that give rise to their antibiotic resistance and epidemic behaviour.

Acinetobacter Infections↗
PubMed2005

Repetitive-DNA-element PCR fingerprinting and antibiotic resistance of pan-European multi-resistant Acinetobacter baumannii clone III strains.

In the present study, it was shown that repetitive-DNA-element PCR fingerprinting using the (GTG)5 primer [(GTG)5-PCR] is a rapid and reliable tool to genotypically differentiate members of the recently described pan-European multi-resistant Acinetobacter baumannii (MAB) clone III from the known MAB clones I and II. The identification of four new representatives of the MAB clone III dating from 1991 to 1993 by (GTG)5-PCR indicates that this clone has persisted in European hospitals since the beginning of the 1990s. Tetracycline (TET) resistance was found to be common among clone III strains, including one strain that also displayed resistance to minocycline. The TET-resistance phenotype in this MAB clone appeared to be strongly associated with the presence of the efflux-type gene tet(A), but the fact that some members lack this gene or have acquired an additional tet gene [i.e. tet(M)] suggests that the tet gene carriage in the pan-European clone III population may have diversified in time and space. In contrast, all clone III strains shared the previously described aminoglycoside resistotype encoded by the aminoglycoside-modifying genes aphA6 and the class 1 integron-associated aadB, which may point to the fact that these genes probably are more stably inherited in MAB clone III compared to tet genes.

Acinetobacter Infections↗
PubMed1986

Pathogenic significance of Acinetobacter calcoaceticus: analysis of experimental infection in mice.

The phenomenon that mixed infection with certain species of bacteria and Acinetobacter calcoaceticus is more virulent than single infection was analyzed experimentally. In mixed infections with A. calcoaceticus paired with either Escherichia coli, Serratia marcescens, or Pseudomonas aeruginosa, the virulence of the latter three organisms was markedly increased over that of single infections only by slime-producing strains of A. calcoaceticus. Of the 100 strains of A. calcoaceticus tested, 14 had slime-producing ability. There was scarcely any difference in the chemical components of the slimes of the two strains tested, but the components of the slime of P. aeruginosa were different from those of these strains. The slime of these two strains exhibited lethal activity in mice, but no correlation was found between the amount of slime produced and the virulence. The slime enhanced the virulence of E. coli, S. marcescens, and P. aeruginosa when it was inoculated along with their viable cells. Furthermore, the slime exhibited potent cell-impairing activity against mouse neutrophils both in vitro and in vivo. This activity was considered to be mainly responsible for the enhancement of virulence in mixed infections.

Acinetobacter↗
PubMed2005

Acinetobacter baumanii folliculitis in a patient with AIDS.

Gram-negative folliculitis usually involves the face and develops in patients with acne or rosacea during long-term antibiotic therapy. Numerous pathogens have been found, but not, until now, Acinetobacter baumanii which has previously been recognized as an important cause of nosocomial infections and hospital outbreaks. We report here a case of A. baumanii folliculitis of the face, neck, arms and upper part of trunk in a patient with AIDS responding to intravenous treatment with ticarcillin-clavulanic acid. The bacterium was not found on healthy skin and the source of the infection remained unknown.

AIDS-Related Opportunistic Infections↗