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None of 50 healthy individuals and only 2 of 50 hospitalized patients (with Acinetobacter anitratus elsewhere) yielded A. anitratus on enrichment from fecal samples.
We report the complete genome sequence of Acinetobacter sp. strain BZX-2, isolated from a hybrid sturgeon (Acipenser baerii ♀ × Acipenser schrenckii ♂). The genome consists of a 3,819,278-bp chromosome with 3,566 predicted protein-coding genes. The genomic characteristics and antibiotic resistance genes identified provide a basis for the prevention and control of sturgeon diseases.
A cluster of 4 cases of meningitis due to Acinetobacter calcoaceticus var anitratus occurred during a 5-day period in a neonatal intensive care unit. Three of the infants were preterm and all had a history of other medical problems. Initiation of intravenous therapy with carbenicillin was accompanied by clinical recovery and a bacteriological cure. Intensive bacteriological investigation failed to show a common source for the infections.
A 56-year-old man sustained an intraocular injury by a piece of steel followed by endophthalmitis, which resolved after lensectomy, vitrectomy, and intravitreal injections of gentamicin. Acinetobacter anitratus was the organism responsible for the endophthalmitis. It is a Gram-negative polymorphic organism that can resemble several other pathogens and possesses unpredictable antibiotic susceptibility. A. anitratus is an important cause of nosocomial infection but has not previously been reported as a cause of endophthalmitis following trauma.
A study was made of the flora of the skin in hospital inpatients and healthy people to demonstrate the presence of non-fermenting Gram-negative rods of the Acinetobacter and Moraxella group. These organisms were found to be present on the skin of 34.3% of inpatients and occurred even more commonly in those patients with kidney disease. It was also present on the skin of 20% of a group of healthy members of staff. This rather high rate of skin carriage is thought to account for the not infrequent occurrence of this organism in blood cultures.
Serotyping of Acinetobacter calcoaceticus by direct immunofluorescence and a capsule swelling reaction is described. One hundred isolates, including 12 from an outbreak in a neonatal department, were studied. Ninety five per cent of the isolates were typable by immunofluorescence and could be divided into 30 separate types, but 42.1% of typable strains, including 11 from the outbreak, were of one type. Typing results by the capsular swelling reaction generally followed those of immunofluorescence methods.
Six hundred and twenty one strains (555 Enterobacteriaceae, 46 Vibrionaceae, and 20 Acinetobacter) were examined in the Mast system. The results were consulted in the code book supplied by the manufacturer and those not listed were processed through the manufacturer's full database held on an Apricot microcomputer in our laboratory. The proportion of strains correctly identified was 88%, with 9% not identified, and 3% incorrectly identified.
Ventriculitis from infection with Acinetobacter calcoaceticus variant anitratus occurred in an infant two weeks after surgical repair of a lumbosacral meningomyelocele and ventriculoperitoneal shunting. Recovery took place on replacing the shunt with an extraventricular deviation device and giving gentamicin and ampicillin intravenously.
A facultatively psychrophilic bacterium isolated from river sediment was identified as an Acinetobacter species, similar to those previously characterized as A. lwoffi. The strain was extremely lipolytic and hemolytic. Some action on crude oil was also observed. The organism was able to utilize a wide variety of carbon and energy sources when tested at both 20 and 30 degrees C. A comparison is made with the previously proposed type strain of A. lwoffi. The bacteria had a Gram-negative cell wall containing an electron-dense intermediate layer. Cell division occurred with the formation of a septum and slight constriction.
A moderately halophilic Acinetobacter sp., capable of producing dextrinogenic amylase, was isolated from sea-sands. Maximum enzyme production was obtained when the bacterium was cultivated aerobically in media containing 1 to 2M NaCl or 1M KCl. Two kinds of amylase, amylases I and II were purified from the culture filtrate to an electrophoretically homogenous state by glycogen-complex formation, DEAE-Sephadex A-50 chromatography, and Sephadex G-200 gel filtration. Both enzymes had maximal activity at pH 7.0 in 0.2 to 0.6 M NaCl or KCl at 50 to 55 degrees C. The activities were lost by dialysis against distilled water. Molecular weights for amylases I and II were estimated to be 55 000 and 65 000 respectively by SDS-gel electrophoresis. The action pattern on amylose, soluble starch, and glycogen showed that the products were maltose and maltotriose.
The synthesis of collagenase in Acinetobacter sp. was found to be inducible by denatured collagen and by its high molecular weight fragments. The presence in the inducer of part of the tertiary structure appear to be indispensable. On the other hand, an addition of Casamino acids, meat protein hydrolysate, or a mixture of amino acids with a similar composition to gelatin does not stimulate collagenase synthesis. Enzyme production was severely repressed in the early phase of growth by glucose, arabinose, and ribose, single amino acids, proline, hydroxyproline, alanine, glutamic acid or casein acid hydrolysate. A mechanism of repression similar to catabolite repression was involved in the phenomenon caused by carbohydrates. However, the fact that cyclic adenosine 3'5-monophosphate did not overcome the repression caused by amino acids or Casamino acids, in contrast to classical catabolite repression, suggests that these two forms of repression may be distinct.
Rhodanese (thiosulfate : cyanide sulfur transferase, EC 2,8,1,1) was found to be contitutively present as an intracellular enzyme in Acinetobacter calcoaceticus. The soluble enzyme was purified 40.9-fold by a procedure which included ultracentrifugation, ethanol precipitation, CM-Sephadex batchwise separation, QAE-50 ion exchange chromatography, and socrose density gradient ultracentrifugation. The enxyme had a molecular weight of approximately 35000 with a pH optimum of 8-8.5. Activity was substantially enhanced by supplements of 2-mercaptoethanol and to a lesser extent by cysteine-HCl or reduced gluthatione. No degradation of the enzyme into smaller subunits was observed when treated with 2-mercaptoethanol.
The sequence of 1895 base pairs of Acinetobacter anitratum genomic DNA, containing the structural gene for the allosteric citrate synthase of that Gram-negative bacterium, is presented. The sequence contains an open reading frame of 424 codons, the 5' end of which is the same as the N-terminal sequence of A. anitratum citrate synthase, less the initiator methionine. The inferred amino acid sequence of the enzyme is about 70% identical with that of citrate synthase from Escherichia coli, which like the A. anitratum enzyme is sensitive to allosteric inhibition by NADH. There is also a more distant homology with the nonallosteric citrate synthases of pig heart and yeast. The gene contains sequences that strongly resemble those found in E. coli promoters, an E. coli type of ribosomal binding site, and a hyphenated dyad sequence at the 3' end of the gene which resembles the rho-independent terminators found in some E. coli genes. The plasmid clone containing the A. anitratum citrate synthase gene pLJD1, originally isolated because it hybridized with the cloned E. coli citrate synthase gene under conditions of reduced stringency, produces large amounts of A. anitratum citrate synthase in an E. coli host which lacks citrate synthase. This work completes proof of the hypothesis that the three major kinds of citrate synthases are formed of similar subunits, although their functional properties are different.
The induction of proteins after a 25 to 5 degrees C cold shock in the psychrotrophic Acinetobacter HH1-l was examined using two-dimensional polyacrylamide gel electrophoresis. In addition, effects of various carbon sources (acetate, Tween 80, and olive oil) on protein synthesis after cold shock were assessed. HH1-1 responded to cold shock by synthesizing both cold shock proteins (csps) and cold acclimation proteins (caps). The synthesis of two csps (89 and 18) was increased 2 h after cold shock by the cells, regardless of the carbon source provided. An additional csp (csp 12), with an estimated molecular mass of 12 kDa, was observed in cells grown in olive oil only. Csp 12 was also synthesized when cells were incubated at 30 degrees C, suggesting that this protein may serve as a general stress protein. In addition to csps, caps were observed post cold shock at 72 h in acetate-grown cells and at 140 h in cells grown in Tween 80 and olive oil. Induction of cold-acclimated periplasmic proteins was observed for cells grown in olive oil only, suggesting cells grown in olive oil may be stressed by low temperatures to a greater extent than cells grown in either acetate or Tween 80.
Acinetobacter calcoaceticus BD413 produces variable amounts of an exocellular lipase that becomes rapidly inactivated upon secretion. To achieve high yield and protect the enzyme, we assayed the addition of several inert compounds to cell-free supernatants, cell fractions, and whole cultures. Glass beads, poly(ethylene glycol) 600, Triton X-100, saccharose, gum arabic, and beta-cyclodextrin were among the compounds tested. beta-Cyclodextrin and gum arabic (and saccharose to a lesser extent) were effective enzyme stabilizers in cell-free supernatants, while gum arabic, glass beads, and Triton X-100 improved lipase secretion from cells, and, therefore, total lipase yield (30-50%, according to the additive). In whole cultures, beta-cyclodextrin was the most effective additive, particularly in combination with glass beads or gum arabic. Indeed, cultures containing beta-cyclodextrin plus gum arabic were able to maintain 95% (+/- 1.5%) of the initial lipase activity for more than 16 h, while control cultures with no additives maintained only 10% (+/- 4%) of the enzyme activity after the same period. In conclusion, the addition of inert compounds in cultures may be considered a useful approach for achieving increased yield and lipase stabilization, amenable for downstream processing.
A total of 96 crude oil-degrading bacterial strains were isolated from 5 geographically diverse sites in India that were contaminated with different types of petroleum hydrocarbons. The strains were identified by sequencing the genes that encode for 16S rRNA. Out of the 96 isolates, 25 strains were identified as Acinetobacter baumannii and selected for the study. All of the selected strains could degrade the total petroleum hydrocarbon fractions of crude oil. These 25 strains were biochemically profiled and grouped into 8 phenovars on the basis of multivariate analysis of their substrate utilization profiles. PCR-based DNA fingerprinting was performed using intergenic repetitive DNA sequences, which divided the selected 25 strains into 7 specific genomic clusters. tRNA intergenic spacer length polymorphism was performed to determine the intra-species relatedness among these 25 strains. It delineated the strains into 8 genomic groups. The present study detected specific variants among the A. baumannii strains with differential degradation capacities for different fractions of crude oil. This could play a significant role in in situ bioremediation. The study also revealed the impact of environmental factors that cause intra-species diversity within the selected strains of A. baumannii.
The genetic and physiological properties of Acinetobacter baylyi strain ADP1 make it an inviting subject for investigation of the properties underlying its nutritional versatility. The organism possesses a relatively small genome in which genes for most catabolic functions are clustered in several genetic islands that, unlike pathogenicity islands, give little evidence of horizontal transfer. Coupling mutagenic polymerase chain reaction to natural transformation provides insight into how structure influences function in transporters, transcriptional regulators, and enzymes. With appropriate selection, mutants in which such molecules have acquired novel function may be obtained. The extraordinary competence of A. baylyi for natural transformation and the ease with which it expresses heterologous genes make it a promising platform for construction of novel metabolic systems. Steps toward this goal should take into account the complexity of existing pathways in which transmembrane trafficking plays a significant role.
OBJECTIVE: To compare the antimicrobial resistance patterns of Acinetobacter baumannii isolates from Shanghai and Hong Kong. MATERIALS AND METHODS: A total of 212 A. baumannii strains of one isolate per patient were collected from Shanghai and Hong Kong from August 2002 to August 2003 that were tested against 15 commonly used antimicrobial agents by the agar dilution method according to the NCCLS guidelines. RESULTS: Most beta-lactams showed no significant increase in activity after adding beta-lactamase inhibitors. The resistance rates of the isolates against ticarcillin-clavulanate, piperacillin-tazobactam and ampicillin-sulbactam were for Shanghai 74.9, 70.9, 69.1% and Hong Kong 24.3, 18.9, 13.5%, respectively. Only cefoperazone-sulbactam showed a significant increase in activity against both Shanghai and Hong Kong strains, as the resistance rates dropped from 93.7 to 8.6% and 83.8 to 5.4%, respectively. The resistance rates of ceftazidime, cefepime, and gentamicin against Shanghai strains were 69.7, 72.0, 73.7% and Hong Kong strains 69.7, 29.7, 18.9%, respectively. About 65% of Shanghai strains were found to be amikacin-resistant, however, all Hong Kong strains were sensitive. Fluoroquinolones including ciprofloxacin and levofloxacin had resistance rates over 60% against Shanghai strains, but only 13.5% against Hong Kong strains. Shanghai strains had imipenem and meropenem resistance rate of 6.3%. Though 10.8% Hong Kong strains were resistant to meropenem, only 2.7% of them were resistant to imipenem. CONCLUSION: A. baumannii isolated from Shanghai were more resistant to all drugs except meropenem than Hong Kong isolates. The results indicate a need for measures to control the abuse of antibiotic usage in order to prevent the emergence of more multidrug-resistant isolates in both cities.