Phylogeny based on elongation factor Tu reflects the phenotypic features of mycoplasmas better than that based on 16S rRNA.

A universal phylogenetic tree of organisms from all kingdoms was constructed by the use of elongation factor Tu (EF-Tu) as the marker molecule. As in the 16S ribosomal RNA (16S rRNA)-based phylogeny, the EF-Tu tree divides eukaryotes, archaebacteria, and prokaryotes into three main branches. Furthermore, the EF-Tu-based tree shows, in contrast to the 16S rRNA tree, some interesting evolutionary relationships between mycoplasmas, better reflecting phenotypic features of these organisms.

[Typing, resistance behavior and occurrence of methicillin-resistant Staphylococcus aureus strains in a surgical intensive care unit]. / Typisierung, Resistenzverhalten und Häufigkeit Methicillin-resistenter Staphylococcus aureus-Stämme einer chirurgischen Intensivstation.

Over a period of three years, the frequency of the appearance of methicillin-resistant S. aureus strains (MRSA) was observed on a surgical intensive care unit. During this above-mentioned period of investigation it came to a heaped occurrence of nosocomial infections on this ICU with altogether 332 S. aureus-stems being isolated from different patient specimen. 204 (61.5%) of these were resistant against methicillin and could be divided into 48 first- and 156 follow-up-isolates. The thereupon accomplished differentiation of the 48 MRSA-first isolates by means of lysotyping and the pioneered GenePath Strain Typing System for a standardized pulsed-field-gel-electrophoresis (PFGE) gave the proof of 7 different MRSA-types. Around 7 different, in part parallel chains of infection on this ICU were observed, which could be led back to different strains. In reference to all analyzed S. aureus, an especially high rate (90%) of MRSA on this ICU could be isolated in taken wound-swabs, followed by 83.3% MRSA at catheter tips and 71,9% in tracheal and bronchial secretion. A consideration of the antibiotic susceptibility yielded, that also gentamicin and the quinolones showed an in-vitro resistance against MRSA, while fosfomycin, fusidic acid, chloramphenicol and trimethoprim/sulfamethoxazole reached positive responding rates between 80 and 100%. On the other hand, presently still 100% of the explored MRSA-strains are susceptible for glycopeptides such as vancomycin and teicoplanin. Because of intensive hospital hygienic measures the number of newly isolated MRSA could be reduced clearly on this ward.

Species differentiation of mycoplasmas by EF-Tu specific monoclonal antibodies.

Ten mouse hybridoma cell lines producing IgG monoclonal antibodies to mycoplasmal elongation factor Tu (EF-Tu) were established. These mAbs showed different degrees of cross-reactivity between mollicutes and even other bacteria. This finding, indicating protein structure diversities of pan bacterial EF-Tu should permit species differentiation of mycoplasmas by epitope pattern analysis of a single protein. Epitope patterns of 23 mollicute type strains and of 40 M. hominis isolates were determined by ELISA. All M. hominis patterns were found to be closely related whereas intrageneric patterns differed in a species specific manner.

Sequence and expression in Escherichia coli of a Mycoplasma hominis gene encoding elongation factor Tu.

We describe the molecular cloning and the complete nucleotide (nt) sequence of a Mycoplasma hominis gene common to a broad range of Mycoplasma species, as defined by hybridization analysis with the cloned gene. Production of M. hominis protein in Escherichia coli was assayed by use of a monoclonal antibody. The nt sequence analysis revealed a 1194-bp open reading frame that could encode a 43 516-Da protein. Computer-aided sequence comparison indicated that the gene codes for elongation factor Tu.