Gijsbert J. Jansen

Effect of twelve antimicrobial drugs on the colonization resistance of the digestive tract of mice and on endogenous potentially pathogenic bacteria

Twelve antimicrobial drugs were studied for their effect on the endogenous aerobic potentially pathogenic bacteria (Enterobacteriaceae, Streptococcus faecalis) in the intestines and on the colonization resistance (CR) of the digestive tract. Three subclasses of antimicrobial drugs could be recognized: (1) those which suppress the CR following low oral doses (rifamycin, penicillin V, cloxacillin, fenethicillin); (2) those in which the CR is suppressed only following relatively high oral doses (amoxycillin); and (3) those in which no obvious suppression of the CR was noticed even following substantial oral doses (nalidixic acid, cinoxacin, co-trimoxazole, oral cephalosporins, piv-mecillinam and doxycyclin). Some of the drugs in the third category were found to suppress endogenous Enterobacteriaceae (nalidixic acid, co-trimoxazole, piv-mecillinam and doxycyclin) and S. faecalis (doxycyclin) at dose levels at which they did not decrease CR.

Computer processing of microscopic images of bacteria: morphometrY and fluorimetry

Several techniques that use computer analysis of microscopic images have been developed to study the complicated microbial flora in the human intestine, including measuring the shape and fluorescence intensity of bacteria. These techniques allow rapid assessment of changes in the intestinal flora and could apply equally to other complex microbial ecosystems.

Very Low Level Fluorescence Detection and Imaging Using a Long Exposure Charge Coupled Device System

A system to improve the sensitivity of an industrial charge coupled device (CCD) video camera by increasing the exposure time is presented. The system consists of an expansion board for the IBM-PC, and interface software. The gain in sensitivity is shown to be a linear function of exposure time. Exposures of up to 8.5 seconds have been tested and they show that a 256-fold increase in sensitivity is attainable.

Escherichia coli as a probiotic

SummaryThe influence of oral treatment with a suspension of non-pathogenicEscherichia coli cells (commercially available as: Symbioflor II®) on the morphological composition of the gut microflora and on the systemic humoral immune response (the IgG-, IgA-and IgM-isotype) against the bacterial cells in the Symbioflor II preparation was measured. After a pretreatment period of 21 days, ten healthy human volunteers ingested 1*108 cells ofE. coli daily for 14 days. Thereafter a follow-up period of 28 days completed the study. The results of this study indicated that no effect of the treatment on the composition of the gut microflora could be observed. However, the immune-fluorescence measurements revealed a significant increase in circulating amounts of IgG directed against the administeredE. coli cells. It is concluded that the treatment only resulted in a specific humoral immune response, while the gut microflora is not modulated.The influence of oral treatment with a suspension of non-pathogenicEscherichia coli cells (commercially available as: Symbioflor II®) on the morphological composition of the gut microflora and on the systemic humoral immune response (the IgG-, IgA-and IgM-isotype) against the bacterial cells in the Symbioflor II preparation was measured. After a pretreatment period of 21 days, ten healthy human volunteers ingested 1*108 cells ofE. coli daily for 14 days. Thereafter a follow-up period of 28 days completed the study. The results of this study indicated that no effect of the treatment on the composition of the gut microflora could be observed. However, the immune-fluorescence measurements revealed a significant increase in circulating amounts of IgG directed against the administeredE. coli cells. It is concluded that the treatment only resulted in a specific humoral immune response, while the gut microflora is not modulated.

Significant decrease of titres of circulating IgG after oral intake of a preparation of Enterococcus faecalis in a group of ten healthy volunteers.

The positive influence of orally ingested, live microorganisms, or probiotics [1] on the health status of the host organism has been recognized since 1907 [2] and is still a controversial subject. Beneficial properties, such as inhibition of potentially pathogenic microorganisms [3] and mutagen inactivation [4] are ascribed especially to Lactobacillus spp. Besides these gut microflora-associated effects, probiotics can exert a modulation of the immune system of the host [5]. The oral ingestion of an antigen may produce synthesis of IgA locally and/or at different secretory sites [6] or it may induce oral tolerance [7]. Despite the fact that in vertebrates other than humans e. g. pigs and ruminants the use of Lactobacillus spp. and Enterococcus spp. as probiotics has become generally adopted [8], little knowledge concerning the use of Enterococcus spp. in humans is available. The influence of Enterococcus species on the immune system of the host is of particular interest since Rusch et al. [9] observed in humans a significant decrease in infection risk associated with the oral intake of viable enterococci. In this letter the effect of daily, oral intake of 107 viable cells of Enterococcus faecalis (Symbioflor I ®, SymbioPharm, Herborn-Dill, Germany) during 3 weeks on the humoral IgG status of the host is presented. Ten healthy volunteers each donated two serum samples (A and B) with a 5-week interval. Immediately after this period each volunteer ingested 107 viable cells of E. faecalis daily, during 3 weeks. After this period a third serum sample (C) was taken from each volunteer. Finally, after a follow-up period of 3 weeks each volunteer delivered the fourth serum sample (D). In each individual serum sample the titre of circulating IgG against E. faecalis was assessed by means of a quantitative immunofluorescence method [10] using FITC-labeled goat-antihuman (Fab2) IgG as a conjugate.

Statistical evaluation of an improved quantitative immunofluorescence method of measuring serum antibody levels directed against intestinal bacteria

Abstract The accuracy of an improved quantitative immunofluorescence method to measure the antibody binding capacity of intestinal bacteria was assessed. The improvements comprise: calibration on a non-fading fluorescence standard (uranyl glass), prolonged camera exposure time (over 4 s) and shading correction of the digitized image. This method can measure levels of IgG, IgM and IgA with variation coefficient of 6.1%, 6.4% and 9.8%, respectively. With this accuracy biological alterations in the antibody binding capacity of intestinal bacteria can be monitored at a statistically significant level.

THE INVITRO INACTIVATION OF 13 BETA-LACTAM ANTIBIOTICS BY OTHER MECHANISMS THAN ADSORPTION TO FECAL SUBSTANCE

SummaryWe have investigated the antibiotic inactivating capacity of intestinal contentsin vitro in faeces. In the presently reported study the influence of β-lactamase catalyzed hydrolysis on the antimicrobial activity of 13 commonly used β-lactam antibiotics was investigated, while the influence of non-specific adsorption of antibiotics to faecal compounds was also taken into account. The following antibiotics were tested: benzylpenicillin, amoxicillin, amoxicillin/clavulanate, cloxacillin, piperacillin, temocillin, cefuroxime, cefamandole, cephradine, cefotaxime, ceftazidime, aztreonam and imipenem. Faecal samples were obtained from 30 healthy volunteers. Six different concentrations of each antibiotic were added to 1 g of faeces. After 24 h of incubation at 37°C the remaining amount of active antibiotic was determined by means of a “growth inhibition assay”. The contribution to the test results of non-specific adsorption to macromolecules was calculated by means of a model and the inactivation data were subsequently corrected. The amount of antibiotic non-specifically bound to faecal macromolecules varied from 0% to 80% of the amount of antibiotic initially added to the faeces. A considerable difference was found in the degree of inactivation of several antibiotics. However, in contrast to earlier investigations, the results of this study show that in a normal population the influence of β-lactamase catalyzed hydrolysis on the activity of β-lactam antibiotics is apparently very small when compared to the influence of non-specific adsorption of β-lactam antibiotics to faecal compounds.ZusammenfassungDie Fähigkeit des Darminhaltes, Antibiotika zu inaktivieren, wurdein vitro untersucht. In der vorliegenden Studie wurde neben der unspezifischen Adsorption von Antibiotika an Stuhlbestandteile vor allem der Einfluß der β-Laktamase-vermittelten Hydrolyse auf die anti-mikrobielle Aktivität von 13 gebräuchlichen β-Laktamantibiotika untersucht (Benzylpenicillin, Amoxicillin, Amoxicillin/Clavulansäure, Cloxacillin, Piperacillin, Temocillin, Cefuroxim, Cefamandol, Cephradin, Cefotaxim, Ceftazidim, Aztreonam und Imipenem). Die Stuhlproben wurden von 30 gesunden Probanden gewonnen. Jedes Antibiotikum wurde in sechs verschiedenen Konzentrationen jeweils zu 1 g Faeces gegeben. Nach 24 h Inkubationszeit bei 37°C wurde mittels „Wachstumshemmtest“ die Restaktivität des Antibiotikums bestimmt. Die Ergebnisse wurden mit dem Faktor der unspezifischen Adsorption an Makromoleküle (Berechnung nach entsprechendem Modell) korrigiert. Von der ursprünglich zugegebenen Antibiotikamenge wurden 0 bis 80% unspezifisch an Makromoleküle der Faeces gebunden. Zwischen dem Inaktivierungsgrad der Antibiotika bestanden beträchtliche Unterschiede. Im Vergleich zur unspezifischen Adsorption an Stuhlbestandteile erwies sich in dieser Studie — im Gegensatz zu früheren Untersuchungen — der Einfluß der Hydrolyse durch β-Laktamasen auf die Antibiotikaaktivität bei gesunden Personen als sehr gering.

The non-enzymatic inactivation of thirteen β-lactam antibiotics in human faeces

SummaryIn order to obtain a method that could predict thein vitro inactivation of an antibiotic in the digestive tract, the non-enzymatic inactivation of 13 β-lactam antibiotics by human faeces was investigated. Benzylpenicillin, amoxicillin, amoxicillin/clavulanate, cloxacillin, piperacillin, temocillin, cefuroxime, cefamandole, cephradine, cefotaxime, ceftazidime, aztreonam and imipenem were mixed in six graded concentrations with faecal suspensions of 30 healthy volunteers. After incubation the remaining antimicrobial activity was measured by means of a serial dilution method. A relationship between the initial antibiotic concentration (Aia) and the remaining antimicrobial activity after incubation (Asd) was derived, namely:

Variations of Bacterial Populations in Human Feces Measured by Fluorescent In Situ Hybridization with Group-Specific 16S rRNA-Targeted Oligonucleotide Probes

Asd = {\raise0.5ex\hbox{