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PubMed1976

Protocatechuate 3, 4-dioxygenase from Acinetobacter calcoaceticus.

Protocatechuate 3,4-dioxygenase (PCD) from p-hydroxybenzoate-induced cells of Acinetobacter calcoaceticus was purified by heat and protamine sulfate treatment, ammonium sulfate fractionation, DEAE-cellulose, and Sephadex G-200 column chromatography. The enzyme appears to be homogeneous by ultracentrifugation and acrylamide gel electrophoresis. This is the first report of PCD purified from Acinetobacter. For comparison, crystalline Pseudomonas PCD was also obtained. The enzymes from Acinetobacter and Pseudomonas are quite similar in their molecular weight, molecular size, and iron content. The specific enzyme activity of PCD from Acinetobacter is about one-third of that from Pseudomonas, despite their similar iron content. Visible and circular dichroism spectra indicate some conformational differences between these two enzymes. Protocatechualdehyde, a competitive deadend inhibitor, binds Pseudomonas PCD more effectively than Acinetobacter PCD. p-Hydroxymercuribenzoate, specific for free-SH groups, inhibits only Acinetobacter PCD and shows no effect on Pseudomonas PCD. Amino acid analyses reveal very low proline and methionine content with higher lysine, glutamic acid, and isoleucine compositions for Acinetobacter PCD. Other properties, including active center conformation, were studied and discussed.

Acinetobacter↗
PubMed1998

Methicillin-resistant Staphylococcus aureus and Acinetobacter baumannii: an unexpected difference in epidemiologic behavior.

BACKGROUND: The Dutch guideline on hospital policy for the prevention of nosocomial spread of methicillin-resistant Staphylococcus aureus (MRSA) states that patients transferred from hospitals abroad must be placed in strict isolation immediately on admission to a hospital in the Netherlands. Three patients colonized with both MRSA and a multiresistant Acinetobacter were transferred from hospitals in Mediterranean countries to 3 different hospitals in the Netherlands. Despite isolation precautions, Acinetobacter spread in 2 of the 3 hospitals, whereas nosocomial spread of MRSA did not occur. METHODS: For outbreak analysis, the Acinetobacter isolates, identified as Acinetobacter baumannii by the use of amplified ribosomal DNA restriction analysis, were comparatively typed by 4 methods. Comparison of isolation measures in the hospitals was performed retrospectively. RESULTS: In the 2 hospitals in which nosocomial spread of Acinetobacter occurred, most of the epidemiologically related isolates were indistinguishable from the index strains. In these 2 hospitals, isolation measures were in concordance with those recommended for the prevention of contact transmission. The precautions of the hospital in which no outbreak occurred included the prevention of airborne transmission. CONCLUSIONS: Precautions recommended for multiresistant gram-negative organisms are insufficient for the prevention of nosocomial spread of multiresistant Acinetobacter. The airborne mode of spread of acinetobacters should be taken into account, and guidelines should be revised accordingly.

Acinetobacter Infections↗
PubMed2006

Dissemination of IMP-1 metallo- beta -lactamase-producing Acinetobacter species in a Brazilian teaching hospital.

OBJECTIVE: To evaluate the emergence and dissemination of metallo- beta -lactamase (MBL)-producing Acinetobacter species. DESIGN: All carbapenem-resistant Acinetobacter strains (1 strain per patient) collected during the period 1993-2001 were evaluated. SETTING: A Brazilian tertiary care teaching hospital (Hospital Sao Paulo, Sao Paulo). METHODS: Seventy-three strains of carbapenem-resistant Acinetobacter species were recovered from the organism bank of the hospital. All isolates were tested for antimicrobial susceptibility by broth microdilution methods, and the production of MBL was initially assessed by phenotypic tests (MBL Etest strip and a disk approximation test). The MBL enzymes were identified by polymerase chain reaction using primers for bla(IMP), bla(VIM), and bla(SPM), followed by gene sequencing. Genetic similarity among the carbapenem-resistant strains was evaluated by automated ribotyping. RESULTS: Only colistin and ampicillin-sulbactam showed reasonable in vitro activity against carbapenem-resistant isolates (97% and 74% of isolates susceptible, respectively). More than half of the isolates (55%) had a positive MBL phenotypic test result and a positive polymerase chain reaction result for bla(IMP-1). The proportion of IMP-1-producing Acinetobacter isolates among carbapenem-resistant strains increased from 0% in the 1993-1997 period to 29% in 1998 and 100% in the 1999-2001 period. No carbapenem-resistant Acinetobacter isolates that harbored bla(VIM) or bla(SPM) were detected. Molecular typing results revealed 20 ribogroups among carbapenem-resistant isolates. During the study period of 1994-2001, we identified 2 major ribogroups, 52-1 (MBL-negative and MBL-positive strains) and 60-7 (MBL-positive strains), that had a coefficient of similarity of 0.85 or higher. CONCLUSIONS: Our results indicate that IMP-1-producing strains of Acinetobacter emerged in our institution in 1998. Since then, production of this MBL was detected not only in the major ribogroups of carbapenem-resistant Acinetobacter species but also among isolates that belonged to 17 distinct ribogroups, indicating that this important mechanism of antimicrobial resistance was disseminated among distinct clones.

Acinetobacter↗
PubMed2000

Bactericidal and bacteriostatic activity of gemifloxacin against Acinetobacter spp. in vitro.

This study compared the in vitro bacteriostatic activity of gemifloxacin (SB-265805) and a panel of test antimicrobial agents against 100 clinical isolates of Acinetobacter spp. (47 Acinetobacter baumannii, 18 Acinetobacter anitratus, 18 Acinetobacter lwoffii, 13 Acinetobacter calcoaceticus and four other Acinetobacter spp.). Gemifloxacin (MIC(50/90) 0.06/16 mg/L) was more than eight-fold more potent than ciprofloxacin (0.5/>128 mg/L), two- to eight-fold more potent than grepafloxacin, moxifloxacin, levofloxacin, ofloxacin and gatifloxacin, and of similar potency to trovafloxacin and sparfloxacin. Cross-resistance was seen only within the quinolone group and did not extend to non-quinolone antimicrobials. The bactericidal activities of gemifloxacin and the six comparator quinolones were investigated by dose-response and time-kill studies against A. baumannii ATCC 19606 at their optimum bactericidal concentration (OBC) and at 4 x MIC. At the OBC there was no significant difference between the quinolones, but at 4 x MIC gemifloxacin showed superior activity, reducing the viable count by almost 2 log(10) in 30 min compared with a 1 log(10) reduction seen with the other drugs. This enhanced killing extended over 24 h, reducing cell numbers by >4 log(10). These data suggest that gemifloxacin has the potential to be of therapeutic value in the treatment of infection by Acinetobacter spp.

Acinetobacter↗
PubMed2004

Unique features revealed by the genome sequence of Acinetobacter sp. ADP1, a versatile and naturally transformation competent bacterium.

Acinetobacter sp. strain ADP1 is a nutritionally versatile soil bacterium closely related to representatives of the well-characterized Pseudomonas aeruginosa and Pseudomonas putida. Unlike these bacteria, the Acinetobacter ADP1 is highly competent for natural transformation which affords extraordinary convenience for genetic manipulation. The circular chromosome of the Acinetobacter ADP1, presented here, encodes 3325 predicted coding sequences, of which 60% have been classified based on sequence similarity to other documented proteins. The close evolutionary proximity of Acinetobacter and Pseudomonas species, as judged by the sequences of their 16S RNA genes and by the highest level of bidirectional best hits, contrasts with the extensive divergence in the GC content of their DNA (40 versus 62%). The chromosomes also differ significantly in size, with the Acinetobacter ADP1 chromosome <60% of the length of the Pseudomonas counterparts. Genome analysis of the Acinetobacter ADP1 revealed genes for metabolic pathways involved in utilization of a large variety of compounds. Almost all of these genes, with orthologs that are scattered in other species, are located in five major 'islands of catabolic diversity', now an apparent 'archipelago of catabolic diversity', within one-quarter of the overall genome. Acinetobacter ADP1 displays many features of other aerobic soil bacteria with metabolism oriented toward the degradation of organic compounds found in their natural habitat. A distinguishing feature of this genome is the absence of a gene corresponding to pyruvate kinase, the enzyme that generally catalyzes the terminal step in conversion of carbohydrates to pyruvate for respiration by the citric acid cycle. This finding supports the view that the cycle itself is centrally geared to the catabolic capabilities of this exceptionally versatile organism.

Acinetobacter↗
PubMedDate not supplied

Acinetobacter infection is associated with acquired glucose intolerance in burn patients.

Infection with antibiotic-resistant Acinetobacter spp. is an increasing problem in critical care environments worldwide. Acinetobacter spp. are known to produce an insulin-cleaving protease. We hypothesized that infection with Acinetobacter spp. was associated with the acquisition of glucose intolerance in burn patients. Data were collected prospectively on all 473 patients admitted to the Burns Centre between January 2002 and March 2003. A total of 3.4% of patients acquired glucose intolerance during admission. Patients with Acinetobacter spp. infection were 9.8 times more likely to develop glucose intolerance than those without the infection (P < .0001). The association persisted after controlling for TBSA (P < .001). In patients with deep Acinetobacter spp. infection, 47% had glucose intolerance, compared with 12% in those with infection of the burn only (P = .03). In patients with pre-existing diabetes mellitus, 27% developed Acinetobacter spp. infection compared with only 8.5% of patients without diabetes (P = .04). This study demonstrates a clear association between Acinetobacter spp. infection and glucose intolerance in burns patients.

Acinetobacter Infections↗
PubMed1997

Discrimination of Acinetobacter genomic species by AFLP fingerprinting.

AFLP is a novel genomic fingerprinting method based on the selective PCR amplification of restriction fragments. The usability of this method for the differentiation of genomic species in the genus Acinetobacter was investigated. A total of 151 classified strains (representing 18 genomic species, including type, reference, and field strains) and 8 unclassified strains were analyzed. By using a single set of restriction enzymes (HindIII and TaqI) and one particular set of selective PCR primers, all strains could be allocated to the correct genomic species and all groups were properly separated, with minimal intraspecific similarity levels ranging from 29 to 74%. Strains belonging to genomic species 8 (Acinetobacter lwoffii sensu stricto) and 9 grouped together in one cluster. The closely related DNA groups 1 (Acinetobacter calcoaceticus), 2 (Acinetobacter baumannii), 3 and 13TU (sensu Tjernberg & Ursing 1989) were clearly distinguishable, with intraspecific linkage levels above 50%. Strains of the independently described genomic species 13BJ (sensu Bouvet & Jeanjean 1989) and 14TU linked together at a relatively low level (33%). Although a previous DNA-DNA hybridization study seemed to justify the unification of these genomic species, AFLP analysis actually divides the 13BJ-14TU group into three well-separated subgroups. Finally, four unclassified strains obtained from diverse sources and origins grouped convincingly together, with a similarity linkage level of approximately 50%. These strains showed no similarities in their AFLP patterns with any of the other 155 strains studied and may represent a thus-far-undescribed Acinetobacter species. Based on these results, AFLP should be regarded as an important auxiliary method for the delineation of genomic species. Furthermore, because AFLP provides a detailed insight into the infraspecific structure of Acinetobacter taxa, the method also represents a highly effective means for the confirmation of strain identity in the epidemiology of acinetobacters.

Acinetobacter↗
PubMed1998

Identification of acinetobacters on blood agar in presence of D-glucose by unique browning effect.

A positive phenotypic characteristic of glucose-oxidizing acinetobacters was demonstrated with blood agar containing D-glucose. Glucose-oxidizing Acinetobacter baumannii, Acinetobacter genospecies 3, Acinetobacter lwoffii, and Acinetobacter genospecies 13 sensu Tjernberg and Ursing caused a unique brown discoloration of media supplemented with 5% blood (of horse, sheep, or human origin) and an aldose sugar (0.22 M D-glucose, D-galactose, D-mannose, D-xylose, or lactose). The browning effect was not observed when a ketose sugar (D-fructose or sucrose) was substituted for the aldose sugar or under high osmolarity in the presence of mannitol, glycerol, or sodium chloride. Other gram-negative nonfermenters (non-glucose-oxidizing acinetobacters, Pseudomonas aeruginosa, other Pseudomonas spp., Stenotrophomonas maltophilia, Flavobacterium spp., and Moraxella spp.) did not cause similar discoloration. This novel browning effect may serve as an alternative trait for identifying glucose-oxidizing acinetobacters.

Acinetobacter↗
PubMed1999

[Antimicrobial resistance of different Acinetobacter baumannii biotypes isolated in the northern region of Chile].

BACKGROUND: Acinetobacter baumannii nosocomial outbreaks are common and the microorganism is frequently resistant to multiple antimicrobials. There is little information about Acinetobacter baumannii antimicrobial susceptibility in the northern region of Chile. AIM: To identify different Acinetobacter baumannii biotypes isolated from clinical samples and to determine their antimicrobial susceptibility. MATERIAL AND METHODS: One hundred twenty three Acinetobacter baumannii isolates were studied. The identification and typing of Acinetobacter baumannii was based on phenotypic characteristics. Antimicrobial susceptibility was investigated using agar dilution techniques. RESULTS: Most Acinetobacter baumannii strains were isolated from wounds, urinary and respiratory infections. Seven biotypes were isolated, being biotype 9 the most frequent. Imipenem was the antimicrobial with the higher activity against the microorganism. Amikacin, cefoperazonesulbactam, ampicillinsulbactam and ceftazidime had a moderate activity. There were high resistance levels to ampicillin and older cephalosporins. CONCLUSIONS: Acinetobacter baumannii is emerging as a significant nosocomial pathogen in Chile and shows high resistance rates to multiple antibiotics.

Acinetobacter↗
PubMed1992

[Occurrence of species from Acinetobacter genus in clinical material and other sources].

The analysis regarded 304 strains of Acinetobacter genus isolated from various diagnostic materials, objects from hospital environment and from non-hospital sources (soil, water, various animals). Applying API ZONE system, five species were isolated: Acinetobacter juni, (18.42%), Acinetobacter baumanii (70.39%), Acinetobacter haemolyticus (5.59%), Acinetobacter lwoffii (4.6%) and Acinetobacter johnsonii (0.99%). Most frequently isolated species were present in purulent materials and in samples from respiratory tract infections and urinary tract infections. Over 47% Acinetobacter species strains were present in clinical material as single aerobic bacteria.

Acinetobacter↗
PubMed2003

Antibodies to Acinetobacter bacteria and bovine brain peptides, measured in bovine spongiform encephalopathy (BSE) in an attempt to develop an ante-mortem test.

Bovine spongiform encephalopathy (BSE) is a neurological disease of cattle. Antibody responses to Acinetobacter radioresistens and six other bacteria, as well as to bovine myelin basic protein and bovine neurofilaments were measured in 128 BSE positive animals, 63 BSE negative animals and 64 healthy control animals. Animals positive for BSE had the highest levels of antibodies to Acinetobacter radioresistens (p < 0.0001) and also autoantibodies to bovine myelin basic protein (p < 0.0001) and bovine neurofilaments (p < 0.0001). In an endeavour to develop an antemortem test for BSE, 12 different strains of Acinetobacter were further tested in a MAN (myelin-Acinetobacter-neurofilament) assay involving 28 BSE positive and 18 BSE negative animals and defined bovine brain peptides. Five out of the 12 Acinetobacter bacteria tested [Acinetobacter (sp3), A. haemolyticus (sp4), A. johnsonii (sp7), A. lwoffii (sp8) and Acinetobacter (sp9)] gave 100% sensitivity and 100% specificity for detecting BSE. The highest anti-bacterial antibody level compared to controls was obtained with A. johnsonii. Further field studies are required to determine the validity of the MAN assay in detecting animals affected with BSE.

Acinetobacter↗
PubMed1991

[Sensitivity of bacteria of the genus Acinetobacter to antibiotics and ofloxacin].

Between 1989-1989 276 strains of Acinetobacter genus were isolated which contained: Acinetobacter calcoaceticus subsp. anitratus (n = 167), Acinetobacter calcoaceticus subsp. Iwoffi (n- = 83), Acinetobacter haemolyticus (n = 26). Their sensitivity to aminoglycoside antibiotics, beta-lactams, tetracyclines, chloramphenicol, colistin, and ofloxacin was tested. More than 90% of strains were sensitive to colistin and ofloxacin. The sensitivity to remaining antibiotics differentiated depending on species. Acinetobacter anitratus were highly resistant to Ist and IInd generation of cephalosporins, and moreover to penicillins, tetracyclines, and chloramphenicol. Cephalosporins of IIIrd generation were active against 70% of strains with exception of cefoperazone what was also the case for representatives of aminoglycosides as netilmicin and amikacin. Strains of Acinetobacter Iwoffi were in majority sensitive to all antibiotics with exception of cephalothin, cephradine and cefoperazone. More than 90% of Acinetobacter haemolyticus strains were sensitive to gentamicin, carbenicillin, azlocillin, ceftriaxone, cefotaxime and tetracyclines.

Acinetobacter↗
PubMed2003

Competitive growth of Gordonia and Acinetobacter in continuous flow aerobic and anaerobic/aerobic reactors.

Gordonia amarae and Acinetobacter calcoaceticus pure culture experiments were conducted in continuous flow chemostats fed with an acetate/mineral salts medium under aerobic and anaerobic-aerobic conditions. The growth parameters such as volatile suspended solids (VSS) suggest that Acinetobacter can successfully out-compete Gordonia under both aerobic and anaerobic-aerobic conditions when both are present in a dual culture. Gordonia was reduced to near detection limits (<10 mg VSS/1), while Acinetobacter successfully grew to about 300 mg VSS/1 when both were grown as a dual culture in a single-stage aerobic chemostat with an initial concentration of 200 mg VSS/1 each. In a two-stage anaerobic-aerobic chemostat with recycling, Gordonia was completely washed out in about 24 h, whereas, Acinetobacter successfully grew to over 170% of its initial concentration. In a single-stage aerobic chemostat, a mathematical model describing the competitive growth of the two species based on single culture kinetic parameters predicted Gordonia washout in <30, and the same was observed from experiments. The model predicted an Acinetobacter concentration of 200% of its initial concentration in about 30 h, while experimentally this value was about 150%. Under anaerobic-aerobic conditions, the two-stage model predicted Gordonia washout and an Acinetobacter concentration of about 170% of the initial concentration. The experimental results agreed with the prediction, but the decrease in the Gordonia and increase in the Acinetobacter concentrations were much more rapid than predicted by the model.

Journal Article↗
PubMed1994

High levels of multiple metal resistance and its correlation to antibiotic resistance in environmental isolates of Acinetobacter.

Forty strains of Acinetobacter were isolated from different environmental sources. All the strains were classified into four genospecies, i.e., A. baumannii (33 isolates), A. calcoaceticus (three isolates), A. junii (three isolates) and A. genospecies3 (one isolate). Susceptibility of these 40 strains to salts of 20 heavy metals and 18 antibiotics was tested by the agar dilution method. All environmental isolates of Acinetobacter were resistant to multiple metal ions (minimum 13 metal ions) while all but one of the strains were resistant to multiple antibiotics (minimum four antibiotics). The maximum number of strains were found to be sensitive to mercury (60% strains) while all strains were resistant to copper, lead, boron and tungsten even at 10 mM concentration. Salts of these four metal ions may be added to the growth medium to facilitate selective isolation of Acinetobacter. Rifampicin and nalidixic acid were the most toxic antibiotics, inhibiting 94.5 and 89.5% of the acinetobacters, respectively. A. genospecies3 was found to be the most resistant species, tolerating high concentrations of all the 20 metal ions and also to a greater number of antibiotics than any other species of Acinetobacter tested. An inhibitory concentration (10 mM) of Ni(2+) and Zn(2+) was observed to inhibit the growth of all of the clinical isolates but allowed the growth of the environmental isolates, facilitating the differentiation between pathogenic and non-pathogenic acinetobacters.

Acinetobacter↗
PubMed1988

Endemic Acinetobacter anitratus in a surgical intensive care unit: mechanical ventilators as reservoir.

Colonization and infection with an endemic multiresistant strain of Acinetobacter calcoaceticus variety anitratus had been observed in the surgical intensive care unit of a university hospital since 1982. An outbreak of infection with this endemic, multiresistant Acinetobacter anitratus strain occurred between January and September, 1984. After initial attempts at identification of environmental reservoirs had been unsuccessful, risk factors for the acquisition of Acinetobacter anitratus were investigated by comparing the epidemiological characteristics of patients who became colonized or infected with those of control patients without colonization. The results of this case-control study and of the ensuing specific cultures indicated that ventilators in use in the unit were the reservoirs of Acinetobacter anitratus, resulting in frequent nosocomial respiratory tract infections. After modification of the mechanical ventilators, colonization and infection rates with Acinetobacter anitratus decreased. Since January 1985, no new cases of colonization or infection with this endemic strain of Acinetobacter anitratus have been recorded.

Acinetobacter↗
PubMed1994

Acinetobacter spp., saprophytic organisms of increasing pathogenic importance.

Acinetobacter spp. are Gram-negative non-fermentative bacteria commonly present in soil and water as free-living saprophytes; they are isolated as commensals from skin, throat and various secretions of healthy people. There have been frequent changes in their taxonomy so that their pathogenic role in humans has been understood only recently: Acinetobacter has emerged as an important nosocomial pathogen involved in outbreaks of hospital infections. This ubiquitous organism can be recovered from the hospital environment, from colonized or infected patients or from staff (hand carriage). Acinetobacter as an opportunistic pathogen is involved in nosocomial urinary tract infections, bacteremia, wound and burn infections. Its predominant role is observed in nosocomial pneumonia, particularly in fan-associated pneumonia. Acinetobacters are responsible for difficult-to-treat infections due to their frequent multiple resistance to major antibiotics available for the treatment of nosocomial infections. Various mechanisms of resistance to beta-lactams and aminoglycosides have been recognized in these bacteria. Combination therapy is usually recommended for the treatment of nosocomial infections. The increasing pathogenic importance of Acinetobacter spp. and the increasing frequency of hospital outbreaks of acinetobacter infections has made the development of reliable typing methods imperative. Beside conventional "phenotypic" methods (serology, phage typing), genotypic systems (ribotyping, plasmid profiles, pulse-field gel electrophoresis) are currently advancing.

Acinetobacter↗
PubMed2002

Epidemiological typing and prevalence of integrons in multiresistant Acinetobacter strains.

Seventy-seven Acinetobacter isolates were recovered from patients in a Korean hospital during the period from November to December 1998. The isolates were genotyped using randomly amplified polymorphic DNA (RAPD) analysis for epidemiological relationship, and investigated for antibiotic susceptibility and presence of integrons. Sixty-nine Acinetobacter baumannii isolates were distributed into five groups by RAPD profiles, with 5, 1, 60, 2 and 1 in each group. The major RAPD group of 60 isolates was further divided into six subgroups by antibiograms. Eight isolates belonging to Acinetobacter DNA group 13TU were distributed among six RAPD groups. Seventy-three of the Acinetobacter isolates were resistant to eight or more of the antibiotics tested. Integrase genes were detected in 66 of the 69 A. baumannii (96%) and in 5 of the 8 Acinetobacter DNA group 13TU isolates (63%). The intI1 and intI2 genes were found in 63 and 8 isolates, respectively. The intI3 gene was not detected. All integron-carrying isolates were resistant to multiple antibiotics. All strains isolated from more than one patient carried integrons. According to the results, the presence of integrons was significantly (p<0.01) associated with multiple antibiotic resistance and nosocomial spread in Acinetobacter strains.

Acinetobacter↗
PubMed2002

Multiresistant Acinetobacter infections: a role for sulbactam combinations in overcoming an emerging worldwide problem.

Recent studies have highlighted the emergence of infections involving multiresistant Acinetobacter clinical isolates. Sulbactam offers direct antimicrobial activity against Acinetobacter species. Accordingly, co-administration of sulbactam with ampicillin or cefoperazone offers the potential of effective empirical therapy against Acinetobacter and other bacteria such as Enterobacteriaceae in institutions in which they are susceptible. Many in vitro studies have indicated that Acinetobacter remains fully susceptible to ampicillin-sulbactam or cefoperazone-sulbactam. Furthermore, ampicillin-sulbactam has proven clinically effective and well tolerated in the treatment of severe acinetobacter infections, including bacteremia. Therefore, ampicillin-sulbactam is a sensible option for the treatment of life-threatening acinetobacter infections.

Acinetobacter↗