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Biomedical subjects

A Lidbeck

Publications and source records attributed to A Lidbeck.

9 recordsLinked to original sources

Lactobacilli and the normal human anaerobic microflora.

The normal human microflora is a complex and usually stable ecosystem. The intestinal microflora is important to the host with regard to many metabolic functions and in resistance to bacterial infections. Administration of antimicrobial agents may disrupt the normal microflora, leading to a decrease in colonization resistance and alterations in metabolic activities of the intestinal bacteria. Antimicrobial therapy may also be accompanied by gastrointestinal disturbances and a reduction or elimination of lactobacilli in the intestinal microflora. Lactobacilli are part of the normal gram-positive anaerobic microflora. Through the production of lactic and acetic acids, hydrogen peroxide, and antimicrobial substances, these microorganisms possibly contribute to the maintenance of colonization resistance. Several studies have indicated a protective effect of lactobacilli against potential pathogens in the gastrointestinal tract. In view of these beneficial properties, it is considered important to maintain or increase the levels of lactobacilli in the intestinal microflora.

Animals

Lactobacilli, anticarcinogenic activities and human intestinal microflora.

Lactobacilli belong to the normal oropharyngeal and intestinal microflora in humans. These microorganisms contribute to the stabilization of the microflora and maintain the colonization resistance against pathogens. Lactobacilli have been used as dietary supplements in order to prevent gastrointestinal disturbances. Claims have been made that certain strains of lactobacilli possibly exert anticarcinogenic activities. The activity of bacterial enzymes, implicated in colon carcinogenesis may be elevated by a high meat, Western-type diet. Supplements of Lactobacillus acidophilus decreased these levels in both rats and humans. Colon cancer patients given L. acidophilus fermented milk showed a significant increase both in numbers of intestinal lactobacilli and dietary calcium intake, while decreasing trends in levels of both soluble faecal bile acids and faecal bacterial enzymes, two risk makers for colon cancer, were observed. In vitro studies have revealed that lactobacilli and other lactic acid bacteria have the ability to absorb cooked food mutagens. Recent studies in humans have shown that intake of L. acidophilus significantly reduced the mutagen excretion after consumption of fried meat. Several mechanisms by which lactobacilli might exert anticarcinogenic effects are discussed. Thus, certain strains of lactobacilli might lower the colon cancer risk in humans.

Bacterial Physiological Phenomena

Effect of lactic acid producing bacteria on the human intestinal microflora during ampicillin treatment.

20 healthy volunteers participated in a double blind study concerning the effect of lactic acid producing bacteria on the intestinal microflora during ampicillin treatment. 10 volunteers received 500 mg ampicillin tablets t.i.d. together with capsules containing lactic acid producing bacteria (Lactobacillus acidophilus and Bifidobacterium bifidum) for 7 days, and the other 10 volunteers were given 500 mg ampicillin tablets together with placebo capsules t.i.d. for 7 days. Both groups of volunteers continued the intake of the capsules t.i.d. for another 14 days after the ampicillin administration had been completed. The number of enterococci, streptococci and corynebacteria decreased during ampicillin administration but returned to normal levels after 14 days. Yeasts increased during the antibiotic treatment but returned to the same levels as before treatment within 14 days. Escherichia coli strains were suppressed in most volunteers during ampicillin administration. The numbers of anaerobic gram-positive cocci and rods decreased in most subjects during ampicillin treatment but were normalized within 2 weeks. Bacteroides strains were recovered in higher numbers in the lactic acid producing bacteria group compared to the placebo group. The volunteers receiving lactic acid producing bacteria were recolonized slightly faster than those having placebo. There were adverse effects observed in 3 subjects receiving ampicillin plus placebo. In the lactic acid producing bacteria group, one subject had diarrhoea on day 3 to on day 3 to day 7.

Adult

Lactobacilli in relation to human ecology and antimicrobial therapy.

The establishment of lactobacilli in the gastrointestinal tract is believed to contribute to the stabilization of the microflora of healthy subjects and to exert beneficial effects on the host. Because of these proposed healthful properties, several Lactobacillus species have been used especially to prevent gastrointestinal disturbances. Though there have been several studies of the possible beneficial effects of lactobacilli in humans, there is still no conclusive evidence for the therapeutic value of these microorganisms.

Anti-Bacterial Agents

Impact of Lactobacillus acidophilus on the normal intestinal microflora after administration of two antimicrobial agents.

Twenty healthy volunteers participated in a comparative study concerning the influence of Lactobacillus acidophilus supplements on the normal intestinal microflora after the administration of two antimicrobial agents, enoxacin and clindamycin, respectively. L. acidophilus NCFB 1748 was given as a fermented milk product containing 5 x 10(8)-2 x 10(9) CFU/ml to ten of the volunteers immediately after the administration of the antimicrobial agents. On the seventh day of enoxacin administration enterobacteria were eliminated in nine of ten subjects. Enterococci disappeared or decreased significantly in five subjects. During the L. acidophilus supplementation, there was a significant increase in the number of Escherichia coli in one subject, while enterococci returned to the same level as before enoxacin administration in all subjects.

Adult

Effect of enoxacin on colonic microflora of healthy volunteers.

Ten healthy volunteers received 400 mg enoxacin orally twice daily for seven days. Fecal specimens were collected at 0, 2, 4, 7, 9, 11, 16 and 21 days to study the effect of enoxacin on the normal colonic microflora. On the seventh day the fecal mean concentration of enoxacin was 348 mg/kg feces. Whereas enterobacteria were strongly suppressed during the administration of enoxacin, the gram-positive and anaerobic microflora was not significantly altered. Two weeks after enoxacin was discontinued, the colonic microflora had returned to normal.

Adult

Comparative effects of enoxacin and norfloxacin on human colonic microflora.

Ten healthy volunteers received 400 mg of enoxacin and another ten healthy volunteers received 200 mg of norfloxacin orally twice a day for 7 days. Fecal specimens were collected before, during, and after drug administration to study the impact of enoxacin and norfloxacin on the normal colonic microflora. On day 7, the mean concentrations of enoxacin and norfloxacin were 350 and 950 mg/kg of feces, respectively. Enoxacin and norfloxacin affected the colonic microflora in similar ways. The number of strains of the family Enterobacteriaceae was markedly suppressed during drug administration, whereas the gram-positive and anaerobic microfloras were not significantly altered. Two weeks after withdrawal of the drugs, the colonic microflora had returned to normal.

Adult

Impact of Lactobacillus acidophilus supplements on the human oropharyngeal and intestinal microflora.

The influence of Lactobacillus acidophilus supplements on the oropharyngeal and intestinal microflora was studied before, during and after L. acidophilus administration. 10 healthy volunteers participated in the study. L. acidophilus was given as a fermented milk product containing 5 X 10(8)-2 X 10(9) CFU/ml in a dose of 250 ml twice a day for 7 days. Only minor changes in the number of aerobic and anaerobic microorganisms in the oropharynx were observed, with no increase in the number of lactobacilli. In the aerobic intestinal microflora a decrease in the number of Escherichia coli was observed in 6/10 subjects. Concerning the anaerobic intestinal microflora there was a significant increase in the number of lactobacilli in 9/10 subjects within 7 days of L. acidophilus administration. The increase in the number of lactobacilli remained as long as the subjects were consuming the L. acidophilus preparation. Lactobacilli returned to the same level as before the study 9 days after the L. acidophilus administration was stopped. Anaerobic cocci showed a decrease in 4/10 subjects, while the number of other anaerobic bacteria remained relatively constant throughout the observation time. These studies suggest that L. acidophilus in this type of preparation should be taken continuously in order to maintain high levels of lactobacilli in the intestine.

Adult