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Medicine Nov 2023Actinobacillus ureae (A. ureae) is an unusual commensal of human respiratory flora, rarely causing human infection. The predisposing factors, identification, clinical... (Review)
Review
RATIONALE
Actinobacillus ureae (A. ureae) is an unusual commensal of human respiratory flora, rarely causing human infection. The predisposing factors, identification, clinical features, and antibiotic therapy of A. ureae are seldomly reported. Herein, we present a case of 64-year-old man affected by A. ureae pneumonia after intracranial surgery.
PATIENT CONCERNS AND DIAGNOSES
A 64-year-old male was admitted with vomiting, drowsiness, and a severe disturbance of consciousness and was later diagnosed with cerebral hemorrhage by computed tomography images. After a craniocerebral surgery, the patient suffered from intractable pneumonia, experiencing treatment failure with multiple anti-bacterial agents. Sputum culture yield pure colonies of A. ureae, confirmed by matrix-assisted laser desorption/ionization time of flight and 16S rRNA gene sequencing.
INTERVENTIONS
Minocycline (100 mg p.o. per 12 hours) with a course of 15 days was administrated for this patient.
OUTCOMES
The respiratory symptoms, presenting as intermittent coughing with purulent and yellowish sputum, were gone. A 3-month follow-up examination showed a complete resolution of radiological findings.
LESSONS
Clinically, the actual incidence of A. ureae pneumonia may be higher than that we generally recognized, and clinicians should consider A. ureae as a possible etiologic agent in patients with predispositions. Currently, A. ureae may be susceptible to penicillin, ampicillin, and third-generation cephalosporins. Other antibacterial agents, such as tetracycline, amoxicillin/clavulanic acid, and aminoglycosides also respond well and can be a choice in the treatment of A. ureae infections.
Topics: Male; Humans; Middle Aged; RNA, Ribosomal, 16S; Actinobacillus; Actinobacillus Infections; Anti-Bacterial Agents; Pneumonia
PubMed: 37986302
DOI: 10.1097/MD.0000000000036087 -
New Microbes and New Infections Nov 2016A 62-year-old man with asthma sought care for intermittent fever, cough with expectoration, breathlessness and orthopnoea with grunting. Computed tomography revealed...
A 62-year-old man with asthma sought care for intermittent fever, cough with expectoration, breathlessness and orthopnoea with grunting. Computed tomography revealed clusters of centrilobular nodules on both sides with a tree-in-bud appearance and mild diffuse bronchial wall thickening. Sputum sample grew pure colonies of which was confirmed by MALDI-TOF and 16SrRNA gene sequencing. A. ureae may be an additional bacteriologic causative agent of the tree-in-bud pattern on computed tomographic scan.
PubMed: 27752324
DOI: 10.1016/j.nmni.2016.09.005 -
Biochemistry Apr 2019Class I ribonucleotide reductases (RNRs) share a common mechanism of nucleotide reduction in a catalytic α subunit. All RNRs initiate catalysis with a thiyl radical,...
Class I ribonucleotide reductases (RNRs) share a common mechanism of nucleotide reduction in a catalytic α subunit. All RNRs initiate catalysis with a thiyl radical, generated in class I enzymes by a metallocofactor in a separate β subunit. Class Id RNRs use a simple mechanism of cofactor activation involving oxidation of a Mn cluster by free superoxide to yield a metal-based MnMn oxidant. This simple cofactor assembly pathway suggests that class Id RNRs may be representative of the evolutionary precursors to more complex class Ia-c enzymes. X-ray crystal structures of two class Id α proteins from Flavobacterium johnsoniae ( Fj) and Actinobacillus ureae ( Au) reveal that this subunit is distinctly small. The enzyme completely lacks common N-terminal ATP-cone allosteric motifs that regulate overall activity, a process that normally occurs by dATP-induced formation of inhibitory quaternary structures to prevent productive β subunit association. Class Id RNR activity is insensitive to dATP in the Fj and Au enzymes evaluated here, as expected. However, the class Id α protein from Fj adopts higher-order structures, detected crystallographically and in solution. The Au enzyme does not exhibit these quaternary forms. Our study reveals structural similarity between bacterial class Id and eukaryotic class Ia α subunits in conservation of an internal auxiliary domain. Our findings with the Fj enzyme illustrate that nucleotide-independent higher-order quaternary structures can form in simple RNRs with truncated or missing allosteric motifs.
Topics: Actinobacillus; Adenosine Triphosphate; Allosteric Regulation; Amino Acid Sequence; Biocatalysis; Catalytic Domain; Crystallography, X-Ray; Deoxyribonucleotides; Flavobacterium; Models, Molecular; Phylogeny; Protein Conformation; Ribonucleotide Reductases; Scattering, Small Angle; Sequence Homology, Amino Acid; X-Ray Diffraction
PubMed: 30855138
DOI: 10.1021/acs.biochem.8b01252 -
Environment International Jun 2019The size nature of sludge flocs could affect the occurrence and distribution of bacterial pathogens in wastewater treatment plants (WWTPs). In this study, the floc-size...
The size nature of sludge flocs could affect the occurrence and distribution of bacterial pathogens in wastewater treatment plants (WWTPs). In this study, the floc-size dependence of bacterial pathogens in the activated sludge of a WWTP was investigated using high-throughput metagenomic sequencing approaches. The results showed that a total of 423 pathogenic species belonging to 123 genera were identified in the three size-fractionated flocs. Also, we found that all the pathogens on the WHO's global priority pathogens list were detected in the size-fractionated flocs, with relative abundance of 0.4%, 0.3% and 0.3% for large-size, medium-size and small-size flocs, respectively, indicating the severe human and environmental health risks of activated sludge. Importantly, our results revealed that the pathogenic species showed a clear floc-size dependent distribution manner, leading to significant differences (P < 0.05) of pathogenic communities among the size-fractionated flocs. Additionally, by partitioning pathogens based on the occurrence and significant difference in abundances, we suggested the following distribution features: 1) large flocs-associated pathogens, such as Borrelia recurrentis, Actinobacillus ureae and Campylobacter gracilis; 2) medium flocs-associated pathogens, such as Mycobacterium szulgai and Ureaplasma urealyticum; and 3) small flocs-associated pathogens, such as Rickettsia akari, Staphylococcus anginosus and Helicobacter cinaedi. Overall, this study provides a comprehensive understanding of pathogens in activated sludge, which is expected to aid in assessment and management of pathogen risks.
Topics: Bacteria; Bioreactors; Flocculation; Humans; Sewage
PubMed: 30991220
DOI: 10.1016/j.envint.2019.04.002