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Clinical Infectious Diseases : An... May 2023Acinetobacter baumannii-calcoaceticus complex is the most commonly identified species in the genus Acinetobacter and it accounts for a large percentage of nosocomial...
Acinetobacter baumannii-calcoaceticus complex is the most commonly identified species in the genus Acinetobacter and it accounts for a large percentage of nosocomial infections, including bacteremia, pneumonia, and infections of the skin and urinary tract. A few key clones of A. baumannii-calcoaceticus are currently responsible for the dissemination of these organisms worldwide. Unfortunately, multidrug resistance is a common trait among these clones due to their unrivalled adaptive nature. A. baumannii-calcoaceticus isolates can accumulate resistance traits by a plethora of mechanisms, including horizontal gene transfer, natural transformation, acquisition of mutations, and mobilization of genetic elements that modulate expression of intrinsic and acquired genes.
Topics: Humans; Acinetobacter baumannii; Anti-Bacterial Agents; Acinetobacter calcoaceticus; Acinetobacter Infections; Acinetobacter; Bacteremia; Drug Resistance, Multiple, Bacterial
PubMed: 37125466
DOI: 10.1093/cid/ciad109 -
Ocular Immunology and Inflammation Sep 2023- complex is emerging as one of the most common causes of hospital-acquired infection globally. We present a case of orbital cellulitis caused by the complex. A... (Review)
Review
- complex is emerging as one of the most common causes of hospital-acquired infection globally. We present a case of orbital cellulitis caused by the complex. A 73-year-old Chinese woman with a history of rheumatoid arthritis presented with subacute onset of right upper eyelid swelling for 1 week. Computer tomography revealed a post-septal soft tissue lesion located at the right superior orbit that was enhanced with contrast, compressing on the superior aspect of the globe. Anterior orbitotomy with incisional biopsy of the right superior orbital lesion was performed, and histopathological examination was consistent with nonspecific inflammatory mass. The microbiological culture of the specimen yielded and complex, which was sensitive to ciprofloxacin, ampicillin, and gentamicin. The infection resolved after a 1-week course of intravenous augmentin. Ophthalmologists should be alert to the possibility of patients having and in periorbital cellulitis.
Topics: Female; Humans; Aged; Acinetobacter baumannii; Acinetobacter calcoaceticus; Orbital Cellulitis; Acinetobacter Infections; Orbit
PubMed: 36074653
DOI: 10.1080/09273948.2022.2103715 -
The Journal of Antimicrobial... Feb 2021This study analysed the novel carbapenem-hydrolysing class D β-lactamase OXA-822 identified in the clinical Acinetobacter calcoaceticus isolate AC_2117.
OBJECTIVES
This study analysed the novel carbapenem-hydrolysing class D β-lactamase OXA-822 identified in the clinical Acinetobacter calcoaceticus isolate AC_2117.
METHODS
WGS was employed for identification of β-lactamases. Micro-broth dilution was used for evaluation of antibiotic susceptibility of AC_2117 and transformants containing blaOXA-822. After heterologous purification of OXA-822, OXA-359 and OXA-213, enzyme kinetics were determined using spectrometry. The effect of OXA-822 upon meropenem treatment was analysed in the Galleria mellonella in vivo infection model.
RESULTS
OXA-822 is a member of the intrinsic OXA-213-like family found in A. calcoaceticus and Acinetobacter pittii. Amino acid sequence similarity to the nearest related OXA-359 was 97%. Production of OXA-822, OXA-359 and OXA-213 in Acinetobacter baumannii ATCC® 19606T resulted in elevated MICs for carbapenems (up to 16-fold). Penicillinase activity of the purified OXA-822 revealed high KM values, in the millimolar range, combined with high turnover numbers. OXA-822 showed the highest affinity to carbapenems, but affinity to imipenem was ∼10-fold lower compared with other carbapenems. Molecular modelling revealed that imipenem does not interact with a negatively charged side chain of OXA-822, as doripenem does, leading to the lower affinity. Presence of OXA-822 decreased survival of infected Galleria mellonella larvae after treatment with meropenem. Only 52.7% ± 7.7% of the larvae survived after 24 h compared with 90.9% ± 3.7% survival in the control group.
CONCLUSIONS
The novel OXA-822 from a clinical A. calcoaceticus isolate displayed penicillinase and carbapenemase activity in vitro, elevated MICs in different species and decreased carbapenem susceptibility in A. baumannii in vivo.
Topics: Acinetobacter; Acinetobacter calcoaceticus; Anti-Bacterial Agents; Bacterial Proteins; Carbapenems; Microbial Sensitivity Tests; beta-Lactamases
PubMed: 33201995
DOI: 10.1093/jac/dkaa488 -
New Biotechnology Mar 2022Rhamnolipids are predominantly produced from the opportunistic pathogen Pseudomonas aeruginosa, which restricts their scaled-up production and biomedical applications....
Rhamnolipids are predominantly produced from the opportunistic pathogen Pseudomonas aeruginosa, which restricts their scaled-up production and biomedical applications. Moreover, the wound healing property of rhamnolipids is mainly focused on either mono- or di-rhamnolipid congeners, which are obtained after extensive and costly purification procedures. Here, crude rhamnolipids from non-pathogenic Acinetobacter calcoaceticus BU-03 have been prepared and characterized and their wound healing potency evaluated in vitro and in vivo. Rhamnolipid extract was produced in a bioreactor by batch fermentation at a concentration of 12.7 ± 1.4 g/L. Characterization of the extract by Fourier Transform Infrared spectroscopy and mass spectrometry revealed characteristic rhamnolipid peaks. Rha-C10-C10 and Rha-Rha-C10-C10 appeared as the predominant congeners along with minor quantities of six more congeners. The rhamnolipid extract obtained from A. calcoaceticus had no toxicity against mouse fibroblast L929 cells and accelerated their migration. Transforming growth factor beta 1 (TGF-β1) has been shown to promote fibroblast migration by activating Smad3. It was found that the rhamnolipid extract enhanced Smad3 phosphorylation in L929 cells. In vivo studies showed that it promoted wound healing in mice with excisional wounds. The protein levels of TGF-β1 and alpha smooth muscle actin (α-SMA), a highly contractile protein, were significantly increased by 2.56- and 1.51-fold, respectively, in extract-treated compared with vehicle control-treated wounds, indicating that the activation of TGF-β1 signaling is possibly involved in the wound healing effect. These results suggest that a rhamnolipid extract obtained from A. calcoaceticus has potential as a wound healing material for topical application in cutaneous wound treatment.
Topics: Acinetobacter calcoaceticus; Animals; Bioreactors; Glycolipids; Mice; Pseudomonas aeruginosa; Wound Healing
PubMed: 34890838
DOI: 10.1016/j.nbt.2021.12.001 -
New Microbes and New Infections May 2021We herein describe the case of a 38-year-old patient with congenital agammaglobulinemia who presented with community-acquired pneumonia; acute respiratory failure with...
We herein describe the case of a 38-year-old patient with congenital agammaglobulinemia who presented with community-acquired pneumonia; acute respiratory failure with sepsis ensued requiring ICU admission, mechanical ventilation and vasopressors administration. The causative organism was identified as , sensitive to multiple agents. Stewardship was effectively applied; clinical, biologic and radiologic improvement resulted, and the patient was later discharged on ciprofloxacin therapy; improvement being maintained thereafter. This is the first reported case of community-acquired pneumonia in our region.
PubMed: 33898044
DOI: 10.1016/j.nmni.2021.100870 -
Journal of Basic Microbiology Mar 2021A bacterium designated as strain STP14 was isolated from a sewage treatment plant and identified as Acinetobacter calcoaceticus based on 16S ribosomal RNA gene...
A bacterium designated as strain STP14 was isolated from a sewage treatment plant and identified as Acinetobacter calcoaceticus based on 16S ribosomal RNA gene sequencing. Strain STP14 exhibited resistance to several metals such as mercury, cobalt, copper, nickel, lead, and cadmium. Among these metals, the bacterium showed maximum resistance to cadmium in concentration up to 1200 mg/L. The antimicrobial susceptibility test of A. calcoaceticus strain STP14 showed coresistance to all tested antibiotics except tigecycline and chloramphenicol for which 16 ± 1- and 15 ± 1-mm zone of inhibition was observed, respectively. The protein pattern of the crude cellular extract revealed substantial differences in protein bands of untreated control and cadmium treated A. calcoaceticus strain STP14 suggesting variable protein expression under cadmium stress. Metals and antibiotic resistance are increasing phenomenon and universal concern of public health. This study improves our understanding regarding the bacterial coresistance against metals and antibiotics and the possible emergence of multidrug resistance due to selective pressure and coselection in the metal polluted sewage sludge.
Topics: Acinetobacter calcoaceticus; Anti-Bacterial Agents; Drug Resistance, Multiple, Bacterial; Metals, Heavy; Microbial Sensitivity Tests; Sewage; Water Purification
PubMed: 33491793
DOI: 10.1002/jobm.202000538 -
Bioscience Reports May 2024The soluble glucose dehydrogenase (sGDH) from Acinetobacter calcoaceticus has been widely studied and is used, in biosensors, to detect the presence of glucose, taking...
The soluble glucose dehydrogenase (sGDH) from Acinetobacter calcoaceticus has been widely studied and is used, in biosensors, to detect the presence of glucose, taking advantage of its high turnover and insensitivity to molecular oxygen. This approach, however, presents two drawbacks: the enzyme has broad substrate specificity (leading to imprecise blood glucose measurements) and shows instability over time (inferior to other oxidizing glucose enzymes). We report the characterization of two sGDH mutants: the single mutant Y343F and the double mutant D143E/Y343F. The mutants present enzyme selectivity and specificity of 1.2 (Y343F) and 5.7 (D143E/Y343F) times higher for glucose compared with that of the wild-type. Crystallographic experiments, designed to characterize these mutants, surprisingly revealed that the prosthetic group PQQ (pyrroloquinoline quinone), essential for the enzymatic activity, is in a cleaved form for both wild-type and mutant structures. We provide evidence suggesting that the sGDH produces H2O2, the level of production depending on the mutation. In addition, spectroscopic experiments allowed us to follow the self-degradation of the prosthetic group and the disappearance of sGDH's glucose oxidation activity. These studies suggest that the enzyme is sensitive to its self-production of H2O2. We show that the premature aging of sGDH can be slowed down by adding catalase to consume the H2O2 produced, allowing the design of a more stable biosensor over time. Our research opens questions about the mechanism of H2O2 production and the physiological role of this activity by sGDH.
Topics: Acinetobacter calcoaceticus; Hydrogen Peroxide; Glucose 1-Dehydrogenase; Bacterial Proteins; Mutation; Glucose; Substrate Specificity; PQQ Cofactor; Crystallography, X-Ray
PubMed: 38687614
DOI: 10.1042/BSR20240102 -
Epidemiology and Infection Mar 2012This study was performed to determine the prevalence, distribution of specimen sources, and antimicrobial susceptibility of the Acinetobacter calcoaceticus-Acinetobacter...
This study was performed to determine the prevalence, distribution of specimen sources, and antimicrobial susceptibility of the Acinetobacter calcoaceticus-Acinetobacter baumannii (Acb) species complex in Singapore. One hundred and ninety-three non-replicate Acb species complex clinical isolates were collected from six hospitals over a 1-month period in 2006. Of these, 152 (78·7%) were identified as A. baumannii, 18 (9·3%) as 'Acinetobacter pittii' [genomic species (gen. sp.) 3], and 23 (11·9%) as 'Acinetobacter nosocomialis' (gen. sp. 13TU). Carbapenem resistance was highest in A. baumannii (72·4%), followed by A. pittii (38·9%), and A. nosocomialis (34·8%). Most carbapenem-resistant A. baumannii and A. nosocomialis possessed the bla(OXA-23-like) gene whereas carbapenem-resistant A. pittii possessed the bla(OXA-58-like) gene. Two imipenem-resistant strains (A. baumannii and A. pittii) had the bla(IMP-like) gene. Representatives of carbapenem-resistant A. baumannii were related to European clones I and II.
Topics: Acinetobacter Infections; Acinetobacter baumannii; Acinetobacter calcoaceticus; Carbapenems; Cluster Analysis; Cross Infection; Hospitals; Humans; Molecular Typing; Prevalence; Singapore; beta-Lactam Resistance; beta-Lactamases
PubMed: 21733253
DOI: 10.1017/S0950268811001129 -
Gene Jun 1997In natural transformation, DNA in the form of macromolecular fragments can be translocated across the cell envelope of prokaryotic microorganisms. During the past two... (Review)
Review
In natural transformation, DNA in the form of macromolecular fragments can be translocated across the cell envelope of prokaryotic microorganisms. During the past two decades, several, largely mutually contradictory, hypotheses have been forwarded to explain the molecular mechanism and bioenergetics of this translocation process. Other biomacromolecules are translocated across the bacterial cell envelope as well, such as polysaccharides and proteins, the latter for instance in the process of the assembly of type-IV pili. This brings up the question whether or not common components are involved. Here, we review analyses of DNA translocation in Acinetobacter calcoaceticus, a Gram-negative eubacterium that is able to migrate through twitching motility, and also shows a high frequency of natural transformation. DNA uptake in this organism is an energy-dependent process. Upon entry into the cells, the DNA fragments are integrated into the resident chromosome when a sufficiently large region of mutual homology is available (200 to 400 bp). However, this process is rather inefficient, and on the average 500 bp of each incoming fragment is degraded through exonuclease activity. Upon covalent attachment of a bulky protein molecule to the transforming DNA, the DNA-translocation machinery becomes blocked in further translocation activity. Since A. calcoaceticus is not well suited for transposon mutagenesis, a random mutagenesis procedure has been developed, based on the ligation of an antibiotic-resistance marker to random fragments of chromosomal DNA. This method was used to generate several mutants impaired in the natural transformation process. Three of these have been characterized in detail. No components, common to the translocation of macromolecules through the cell envelope of Acinetobacter, have been detected in this screen.
Topics: Acinetobacter calcoaceticus; Cloning, Molecular; DNA, Bacterial; Energy Metabolism; Fimbriae, Bacterial; Genetic Markers; Models, Genetic; Mutagenesis, Insertional; Plasmids; Restriction Mapping; Transformation, Bacterial
PubMed: 9224889
DOI: 10.1016/s0378-1119(97)00042-5 -
Protein Expression and Purification Aug 2019Xanthine oxidase (EC 1.17.3.2) is a key enzyme of purine metabolism and has potential applications in food and pharmaceutical industries. In the present study, a new...
Xanthine oxidase (EC 1.17.3.2) is a key enzyme of purine metabolism and has potential applications in food and pharmaceutical industries. In the present study, a new bacterial source of xanthine oxidase i.e. Acinetobacter calcoaceticus RL2-M4 with high oxidase activity was isolated from soil. The culture conditions were optimized with one variable at a time (OVAT) and response surface methodology (RSM) approaches included: a minimal salt medium (MSM) of pH 7.0 supplemented with 0.8% yeast extract, 8.5 mM xanthine and incubation at 30 °C for 24 h. Under these culture conditions 11.57 fold increase in the production of this enzyme was achieved. The enzyme was purified from A. calcoaceticus RL2-M4 using anion exchange chromatography to 8.18 fold with 31% yield and specific activity of 4.58 U/mg protein. SDS-PAGE analysis of the purified enzyme revealed that it was homodimer of 95 kDa and its native molecular mass was estimated to be 190 kDa. This enzyme was found to be stable at 35 °C for 5 h. The purified xanthine oxidase of A. calcoaceticus RL2-M4 had K 0.3 mM and V 5.8 U/mg protein using xanthine as substrate. The activity and stability characteristic of xanthine oxidase of A. calcoaceticus RL2-M4 makes it a potentially good enzyme for industrial applications.
Topics: Acinetobacter calcoaceticus; Bacterial Proteins; Chromatography, Ion Exchange; Dimerization; Electrophoresis, Polyacrylamide Gel; Enzyme Stability; Hydrogen-Ion Concentration; Kinetics; Molecular Weight; Soil Microbiology; Temperature; Xanthine Oxidase
PubMed: 30926462
DOI: 10.1016/j.pep.2019.03.014