Chronic prosthetic hip infection caused by a small-colony variant of Escherichia coli.
Andreas Roggenkamp,Andreas Sing,Mathias W. Hornef,Brunner U,Ingo B. Autenrieth,Jürgen Heesemann +5 more
TLDR
The first report of a Hem−E.Abstract:
From two different specimens of a chronic prosthetic hip infection taken at an interval of 2 months a slow-growing gram-negative bacterium was isolated in pure culture. The strain grew with the typical features of a small-colony variant (SCV). 16S rRNA sequencing identified the bacterium as Escherichia coli. Biochemical characterization demonstrated multiple phenotypic alterations of a mutant carrying a defect in the heme biosynthetic pathway (Hem−): (i) catalase and nitrate reductase reactions were both negative, (ii) a negative benzidine reaction demonstrated the lack of heme-containing cytochromes, and (iii) growth stimulation under anaerobic conditions as well as gentamicin resistance indicated defective aerobic respiration. PCR and Southern hybridization demonstrated that the mutation of the SCV of E. coli was localized in the hemB gene and was most likely due to a deletion of the hemB gene. On blood agar plates revertants were recognized growing as normal-sized colonies between the dominant small colonies of the strain. Feeding experiments indicated that the revertants but not the small colonies were permeable for hemin. A strong antibody response against the infecting SCV of E. coli was found. To our knowledge, this is the first report of a Hem− E. coli strain as the etiological agent of a chronic bacterial infection.read more
Citations
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Small colony variants: a pathogenic form of bacteria that facilitates persistent and recurrent infections
Richard A. Proctor,Christof von Eiff,Barbara C. Kahl,Karsten Becker,Peter J. McNamara,Mathias Herrmann,Georg Peters +6 more
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Healthcare-associated infections, medical devices and biofilms: risk, tolerance and control.
TL;DR: In order to increase the chances of detection and provide a more accurate diagnosis, a combination of microbiological culture techniques and molecular methods should be employed.
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Bacterial and Fungal Biofilm Infections
TL;DR: This review summarizes the existing data relating to the nature, prevalence, and treatment of biofilm-associated infections and highlights experimental approaches and therapies that are being pursued toward more effective treatments.
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Ribosomal DNA sequencing as a tool for identification of bacterial pathogens
TL;DR: A significant movement is now afoot to use molecular methods for the identification of clinical pathogens due to the relative objectivity of DNA sequence information and growing availability of sequence information databases.
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Small-Colony Variants of Pseudomonas aeruginosa in Cystic Fibrosis
TL;DR: Recovery of SCVs was correlated with parameters revealing poor lung function and was significantly associated with daily inhalation of tobramycin or colistin and MICs of a broad range of antipseudomonas agents for SCVs were two- to eightfold higher than values for revertants.
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