Use of portable enrichment unit in rapid characterization of infantile intestinal enterobacterial microbiota

Development of microbiological field methodology for water and food-chain hygiene analysis of Campylobacter spp. and Yersinia spp. in Burkina Faso, West Africa

Field-adaptable research methods for identifying Campylobacter sp., Yersinia sp. and other pathogenic and indicator bacteria were designed in Finland and tested in Burkina Faso. Several bacterial groups were also validated from artificially contaminated samples. Campylobacter strains were cultivated using an innovative gas generation system: The 'Portable Microbe Enrichment Unit' (PMEU) which provides microaerobic gas flow into the enrichment broth. This enhanced cultivation system produced rapid growth of several isolates of campylobacteria from water and chicken samples. The latter were obtained from local marketplace samples. No yersinias were found in the field studies, whereas they were readily recovered from the spiked samples, as well as Salmonella sp. and Escherichia coli strains. The PMEU method turned out to be reliable for monitoring of water and food hygiene in remote locations.

Composition and antimicrobial activity of the skin peptidome of Russian brown frog Rana temporaria

A nano-HPLC-ESI-OrbiTrap study involving HCD and ETD spectra has been carried out to clarify the composition of the skin peptidome of brown Russian frogs Rana temporaria. This approach allowed determinantion of 76 individual peptides, increasing 3-fold the identified portion of the peptidome in comparison to that obtained earlier with FTICR MS. A search for the new bradykinin related peptides (BRPs) was carried out by reconstructing mass chromatograms based on the ion current of characteristic b- and y-ions. Several peptides were reported in the secretion of R. temporaria for the first time. The overall antibacterial activity of the skin secretion in general and of one individual peptide (Brevinin 1Tb) was determined using PMEU Spectrion (Portable Microbe Enrichment Unit) technology. The inhibitory effects of these peptides on Staphylococcus aureus and Salmonella enterica Serovar typhimutium were equal in scale to that reported for some antibiotics.

Gaseous CO2 signal initiates growth of butyric-acid-producing Clostridium butyricum in both pure culture and mixed cultures with Lactobacillus brevis

Microbial strains produce numerous volatile substances in the anaerobic conditions of the human intestines. The availability of CO(2) is known to be a prerequisite for bacterial growth in general. In experiments with anaerobic Lactobacillus brevis and Clostridium butyricum bacteria in the Portable Microbial Enrichment Unit (PMEU) it was shown that these strains interact; this interaction being mediated by CO(2) emission. CO(2) promoted clostridial growth in pure cultures and mixed cultures with lactobacilli. The growth of C. butyricum in pure cultures was much delayed or did not start at all without CO(2) from outside. Conversely, the onset of growth was provoked by a short (15 min) CO(2) burst. In mixed cultures the presence of lactobacilli in equal numbers speeded up the onset of clostridial growth by 10 h. If C. butyricum cultures designated as PMEU 1, 2, and 3 in cultivation syringes were chained by connecting the gas flow thereby allowing the volatiles of the preceding syringe culture to bubble to the next one, the growth started in 20, 10, or 6 h, respectively. This effect of gaseous emissions from other cultures speeding up the bacterial growth initiation was abolished if the gas was passed through sodium hydroxide to remove the CO(2). The positive contribution of lactobacilli to the growth of butyric-acid-producing clostridia documented in this simulation experiment with PMEU has in vivo implications and indicates molecular communication between the species. CO(2) is a necessary signal for the growth of clostridia, and lactobacilli can promote clostridial growth in mixed cultures where both bacteria grow well with mutual benefit.

Enterobacterial microflora in infancy - a case study with enhanced enrichment

OBJECTIVE

To validate PMEU (Portable Microbe Enrichment Unit) method for monitoring the composition and development of infantile intestinal enterobacterial microflora.

METHODS

A case study of a boy with neonatal sepsis is presented. During the first 32 months, he was given 19 systemic antibiotic treatments representing seven different antibiotic classes. Seven fecal samples collected at ages from 3.4 to 31.6 months were studied for enterobacterial strains by a combination of enhanced enrichment culture in the PMEU and plate culture. The identification and phenotypic characterization of the isolates was performed by biochemical tests.

RESULTS

37/51 (73%) of the enterobacterial isolates were detected only after the PMEU enrichment. In most samples Escherichia coli strains were predominating, but also several Enterobacter, Klebsiella, Pantoea and Proteus strains could be isolated. It seemed that the antibiotic medications remarkably delayed the development of the intestinal microflora, because first enterobacterial strains were detected only after 6 months of age.

CONCLUSIONS

The enrichment step turned out to essentially improve the characterization and monitoring of the intestinal enterobacterial microbiota of infants. Compared to plate culture the amount of isolates was 2.6-fold by the PMEU enrichment. This study gives an idea on the development and succession of microbial communities in the gastrointestinal tract and on the variation of the strains due to the intestinal environmental factors.