Growth and gaseous emissions of pure and mixed small intestinal bacterial cultures: Effects of bile and vancomycin.

Simultaneous cultivations in anaerobiosis, aerobiosis and with microaerobic gas mixture were used to clarify the bile (oxgall) effects on the pure and mixed cultures of enterobacterial strains in simulations in Portable Microbe Enrichment Unit (PMEU) linked with ChemPro100i((R)) gas detector. The effects of vancomycin were evaluated in aerobic cultures. Growth and metabolic activity of cultures were also followed by measuring sugar consumption, pH alterations, and colony counts on BD CHROMagar Orientation plates. Results showed that the two fermentatively different strains of facultative anaerobes, Escherichia coli E 17 and Klebsiella mobilis ATCC 13048 grew in balance regardless of oxygen level, bile acid concentration or other components of the mixed cultures, Bacillus cereus or Staphylococcus aureus. When the evaporations of the mixed cultures of E. coli, K. mobilis and S. aureus were compared with the emissions of the corresponding pure cultures by ChemPro100i((R)) gas sensing detector, the pure cultures of bile resistant E. coli and K. mobilis produced more gaseous components than the mixed culture indicating that these organisms cooperate and use the substrate more effectively together than separately. A survey of the aseptic bacterial isolations from the bile tract in a big University Hospital, (Salzburg, Austria) during 3 years, showed that these bacterial groups dominated. Only 13.24% of the 287 patient samples were sterile, and around 180 strains of both E. coli and Klebsiella/Enterobacter groups were found amongst 973 isolates from 249 patients (together 35.57%). Enterococcus sp. accounted for 246 isolates being the largest group of strains (24.25% of all the isolates). In anaerobiosis it was shown that Klebsiella neutralized the acids produced in the mixed acid fermentation of the E. coli. The ethanol produced from both groups evaporated in the gas stream of the PMEU culturing step and its formation also removes excess acidity from the cultures. The synergistic behaviour and symbiotic function between E. coli and Klebsiella/Enterobacter strains is suggested.

Fast detection of bacterial growth by using Portable Microbe Enrichment Unit (PMEU) and ChemPro100i((R)) gas sensor.

The combination of the Portable Microbe Enrichment Unit (PMEU) cultivation and ChemPro100i((R)) Chemical Detector helps the fast detection of hospital infections. The first alarm of the microbe metabolism and growth in the enrichment culture was achieved in 2-3h when pure cultures of strains isolated from neonatal patients were tested. For the detection of minor concentrations of the bacteria, Bacillus, Staphylococcus, Klebsiella and Escherichia strains were diluted to 0.5-600cells per ml. Their preliminary detection was achieved within 4-5h. The combination of enrichment culture (PMEU) and detection of bacterial products by ion mobility spectrometer is a rapid and sensitive method for diagnosis of bacterial growth. This finding warrants further studies with clinical samples.

Dualistic acidic and neutral glucose fermentation balance in small intestine: Simulation in vitro.

Intestinal microbes live in diminished or deprived oxygen conditions. Facultative anaerobic bacteria of the family Enterobacteriaceae ferment glucose in the gut using two main pathways: mixed acid and neutral fermentations. The aim of the present study was to clarify the roles of these fermentations in an in vitro model. Acid-producing Escherichia coli ATCC 25922 and neutral end-products producing Klebsiella mobilis ATCC 13048 were cultured in a Portable Microbe Enrichment Unit (PMEU) which permitted the selection of the gas phase in standardized conditions. In the butanediol production experiments also Klebsiella pneumoniae ssp. pneumoniae IIIa2 E111 strain was also used. Two isomers of 2,3-butanediol were observed in both aerobic and microaerobic Klebsiella cultures. During 7h cultures both E. coli and K. mobilis grew from densities of some million up to some billions per ml. The growth was almost equal in both aerobic and microaerobic conditions. In anaerobic conditions a balance prevailed in mixed E. coli and Klebsiella cultures between the species (final pH was 5.8-6.1), whereas in aerobic conditions the klebsiellas were favoured, and the pH rose up to about 8.5 (in 20h) as in pure Klebsiella cultures. In microaerobic Klebsiella cultures the final pH varied between 6.7 and 7.5. In mixed cultures the growth yields of both bacteria equalled those of the separate pure cultures indicating mutual benefits of the co-existence. Apparently E. coli produced a set of organic acids, which lowered pH. Klebsiellas increased the pH up to 2units probably due to acid conversion in anaerobic conditions to ethanol. We propose that the balance of acid and ethanol as well 2,3-butanediol fermentations contributes to the small bowel pH regulation, which also aids the host in the nutrient uptake in the small intestine.

Interfacing an aspiration ion mobility spectrometer to a triple quadrupole mass spectrometer.

This article presents the combination of an aspiration-type ion mobility spectrometer with a mass spectrometer. The interface between the aspiration ion mobility spectrometer and the mass spectrometer was designed to allow for quick mounting of the aspiration ion mobility spectrometer onto a Sciex API-300 triple quadrupole mass spectrometer. The developed instrumentation is used for gathering fundamental information on aspiration ion mobility spectrometry. Performance of the instrument is demonstrated using 2,6-di-tert-butyl pyridine and dimethyl methylphosphonate.