Dataset Information

Mechanism of intrinsic resistance to vancomycin in Clostridium innocuum NCIB 10674.

ABSTRACT: We have studied the basis for intrinsic resistance to low levels of vancomycin in Clostridium innocuum NCIB 10674 (MIC = 8 microg/ml). Analysis by high-pressure liquid chromatography (HPLC) and mass spectrometry of peptidoglycan nucleotide precursors pools revealed the presence of two types of UDP-MurNac-pentapeptide precursors constitutively produced, an UDP-MurNAc-pentapeptide with a serine at the C terminus which represented 93% of the pool and an UDP-MurNAc-pentapeptide with an alanine at the C terminus which represented the rest of the pool. C. innocuum cell wall muropeptides containing pentapeptide[Ser], either dialanine substituted on the epsilon amino group of lysine or not, were identified and represented about 10% of the monomers while only 1% of pentapeptide[D-Ala] monomers were found. The sequence of a 2,465-bp chromosomal fragment from C. innocuum was determined and revealed the presence of ddl(c. innocuum) and C. innocuum racemase genes putatively encoding homologues of D-Ala:D-X ligases and amino acid racemases, respectively. Analysis of the pool of precursors of Enterococcus faecalis JH2-2, containing cloned ddl(c. innocuum) and C. innocuum racemase genes showed in addition to the UDP-MurNAc-pentapeptide[D-Ala], the presence of an UDP-MurNAc-pentapeptide[D-Ser] precursor. However, the expression of low-level resistance to vancomycin was observed only when both genes were cloned in E. faecalis JH2-2 together with the vanXYc gene from Enterococcus gallinarum BM4174 which encodes a d,d-peptidase which eliminates preferentially the high affinity vancomycin UDP-MurNAc-pentapeptide [D-Ala] precursors produced by the host. We conclude that resistance to vancomycin in C. innocuum NCIB 10674 was related to the presence of the two chromosomal ddl(c. innocuum) and C. innocuum racemase genes allowing the synthesis of a peptidoglycan precursor terminating in serine with low affinity for vancomycin.

SUBMITTER: David V

PROVIDER: S-EPMC415764 | biostudies-literature | 2004 Jun

REPOSITORIES: biostudies-literature

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Mechanism of intrinsic resistance to vancomycin in Clostridium innocuum NCIB 10674.

David Véronique V Bozdogan Bülent B Mainardi Jean-Luc JL Legrand Raymond R Gutmann Laurent L Leclercq Roland R

Journal of bacteriology 20040601 11

We have studied the basis for intrinsic resistance to low levels of vancomycin in Clostridium innocuum NCIB 10674 (MIC = 8 microg/ml). Analysis by high-pressure liquid chromatography (HPLC) and mass spectrometry of peptidoglycan nucleotide precursors pools revealed the presence of two types of UDP-MurNac-pentapeptide precursors constitutively produced, an UDP-MurNAc-pentapeptide with a serine at the C terminus which represented 93% of the pool and an UDP-MurNAc-pentapeptide with an alanine at th ...[more]

PMID: 15150227

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Project description:Clostridia are a polyphyletic group of Gram-positive, spore-forming anaerobes in the Firmicutes phylum that significantly impact metabolism and functioning of the human gastrointestinal tract. Recently, Clostridia were divided into two separate classes, Clostridia and Erysipelotrichia, based on phenotypic and 16S rRNA gene-based differences. While Clostridia include many well-known pathogenic bacteria, Erysipelotrichia remain relatively uncharacterized, particularly regarding their role as a pathogen versus commensal. Despite wide recognition as a commensal, the erysipelotrichial species Clostridium innocuum has recently been associated with various disease states. To further understand the ecological and potential virulent role of C. innocuum, we conducted a genomic comparison across 38 C. innocuum isolates and 194 publicly available genomes. Based on colony morphology, we isolated multiple C. innocuum cultivars from the feces of healthy human volunteers (n = 5). Comparison of the 16S rRNA gene of our isolates against publicly available microbiota data sets in healthy individuals suggests a high prevalence of C. innocuum across the human population (>80%). Analysis of single nucleotide polymorphisms (SNPs) across core genes and average nucleotide identify (ANI) revealed the presence of four clades among all available genomes (n = 232 total). Investigation of carbohydrate and protein utilization pathways, including comparison against the carbohydrate-activating enzyme (CAZyme) database, demonstrated inter- and intraclade differences that were further substantiated in vitro. Collectively, these data indicate genetic variance within the C. innocuum species that may help clarify its role in human disease and health. IMPORTANCE Clostridia are a group of medically important anaerobes as both commensals and pathogens. Recently, a new class of Erysipelotrichia containing a number of reassigned clostridial species has emerged, including Clostridium innocuum. Recent studies have implicated C. innocuum as a potential causative agent of diarrhea in patients from whom Clostridioides difficile could not be isolated. Using genomic and in vitro comparison, this study sought to characterize C. innocuum in the healthy human gut. Our analyses suggest that C. innocuum is a highly prevalent and diverse species, demonstrating clade-specific differences in metabolism and potential virulence. Collectively, this study is the first investigation into a broader description of C. innocuum as a human gut inhabitant.

Dataset Information

Mechanism of intrinsic resistance to vancomycin in Clostridium innocuum NCIB 10674.

Publications

Mechanism of intrinsic resistance to vancomycin in Clostridium innocuum NCIB 10674.

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