Ulcers as a Sign of Skin Infection with Mycobacterium wolinskyi: Report of a Case and Review of the Literature.

Infection with Mycobacterium wolinskyi, if not detected, may cause severe skin and soft tissue infection with prolonged healing process and is therefore associated with high morbidity. Only about 20 cases of M. wolinskyi infections in humans have been described in the literature until now, none of them in Switzerland. We report a case of an infection in a 72-year-old male patient with recurrent subcutaneous abdominal wall abscesses and ulcer formation after insulin injection in the underbelly. A culture of skin biopsy tissue showed rapid growth of non-tuberculous mycobacteria (NTM), which were identified by 16S rRNA gene sequencing as M. wolinskyi. Surgical excision and primary closure of all abdominal ulcers in combination with antibiotic therapy, based on the antimicrobiotic susceptibility test results, were performed and resulted in complete resolution of the clinical symptoms and no recurrence of infection at a 6-month follow-up. The present case emphasizes the importance of accurate diagnosis and treatment of chronic infection with ulcer formation. In such cases, it is crucial to consider the presence of NTM, such as M. wolinskyi, in order to obtain rapid diagnosis, specific treatment and improved patient care.

Cell-wall deficient L. monocytogenes L-forms feature abrogated pathogenicity.

Stable L-forms are cell wall-deficient bacteria which are able to multiply and propagate indefinitely, despite the absence of a rigid peptidoglycan cell wall. We investigated whether L-forms of the intracellular pathogen L. monocytogenes possibly retain pathogenicity, and if they could trigger an innate immune response. While phagocytosis of L. monocytogenes L-forms by non-activated macrophages sometimes resulted in an unexpected persistence of the bacteria in the phagocytes, they were effectively eliminated by IFN-γ preactivated or bone marrow-derived macrophages (BMM). These findings were in line with the observed down-regulation of virulence factors in the cell-wall deficient L. monocytogenes. Absence of Interferon-ß (IFN-ß) triggering indicated inability of L-forms to escape from the phagosome into the cytosol. Moreover, abrogated cytokine response in MyD88-deficient dendritic cells (DC) challenged with L. monocytogenes L-forms suggested an exclusive TLR-dependent host response. Taken together, our data demonstrate a strong attenuation of Listeria monocytogenes L-form pathogenicity, due to diminished expression of virulence factors and innate immunity recognition, eventually resulting in elimination of L-form bacteria from phagocytes.

Listeria monocytogenes L-forms respond to cell wall deficiency by modifying gene expression and the mode of division.

Cell wall-deficient bacteria referred to as L-forms have lost the ability to maintain or build a rigid peptidoglycan envelope. We have generated stable, non-reverting L-form variants of the Gram-positive pathogen Listeria monocytogenes, and studied the cellular and molecular changes associated with this transition. Stable L-form cells can occur as small protoplast-like vesicles and as multinucleated, large bodies. They have lost the thick, multilayered murein sacculus and are surrounded by a cytoplasmic membrane only, although peptidoglycan precursors are still produced. While they lack murein-associated molecules including Internalin A, membrane-anchored proteins such as Internalin B are retained. Surprisingly, L-forms were found to be able to divide and propagate indefinitely without a wall. Time-lapse microscopy of fluorescently labelled L-forms indicated a switch to a novel form of cell division, where genome-containing membrane vesicles are first formed within enlarged L-forms, and subsequently released by collapse of the mother cell. Array-based transcriptomics of parent and L-form cells revealed manifold differences in expression of genes associated with morphological and physiological functions. The L-forms feature downregulated metabolic functions correlating with the dramatic shift in surface to volume ratio, whereas upregulation of stress genes reflects the difficulties in adapting to this unusual, cell wall-deficient lifestyle.

Biocatalytic racemization of aliphatic, arylaliphatic, and aromatic alpha-hydroxycarboxylic acids.

[reaction: see text] Biocatalytic racemization of a range of aliphatic, (aryl)aliphatic, and aromatic alpha-hydroxycarboxylic acids was accomplished by using whole resting cells of a range of Lactobacillus spp. The mild (physiological) reaction conditions ensured an essentially "clean" isomerization in the absence of side reactions, such as elimination or decomposition. Whereas straight-chain aliphatic 2-hydroxycarboxylic acids were racemized with excellent rates (up to 85% relative to lactate), steric hindrance was observed for branched-chain analogues. Good rates were observed for aryl-alkyl derivatives, such as 3-phenyllactic acid (up to 59%) and 4-phenyl-2-hydroxybutanoic acid (up to 47%). In addition, also mandelate and its o-chloro analogue were accepted at a fair rate (45%). This biocatalytic racemization represents an important tool for the deracemization of a number of pharmaceutically important building blocks.

Biocatalytic racemisation of alpha-hydroxycarboxylic acids at physiological conditions.

Biocatalytic racemisation of aliphatic, aryl-aliphatic and aromatic alpha-hydroxycarboxylic acids was accomplished using whole resting cells of Lactobacillus paracasei DSM 20207; the mild (physiological) reaction conditions ensured an essentially 'clean' isomerization in the absence of side reactions, such as elimination or decomposition.