Expression of the hemolysin trait in a proteolytic transconjugant of Streptococcus faecalis.

Streptococcus faecalis 31H-1 is a proteolytic transconjugant of strain 31B, that harbors the 38.5 Mdal plasmid which codes for hemolysin in strain X14. It fails to express the hemolytic character in broth due to its proteolytic character. Hemolytic activity can be demonstrated when the proteolytic activity is inhibited by 10(-4) M EDTA. The effect of erythromycin (on the donor cells) and of proteinase K during conjugation suggests that the conjugation system involving the 38.5 Mdal plasmid of S. faecalis strain X14 is sex-pherormone mediated.

Bacteriotherapy with Lactobacillus reuteri in rotavirus gastroenteritis.

BACKGROUND: Certain lactic acid bacteria may accelerate recovery from acute diarrhea. Lactobacillus reuteri is a commonly occurring Lactobacillus species with therapeutic potential in diarrhea. DESIGN: Prospective, randomized, placebo-controlled trial in two hospitals. METHODS: Children between 6 and 36 months of age admitted for rotavirus-associated diarrhea were randomized into three groups to receive either 10(10) or 10(7) colony-forming units (cfu) of L. reuteri or a matching placebo once a day for up to 5 days. RESULTS: The main effect of L. reuteri was on the duration of watery diarrhea. The mean (+/-SD) duration of watery diarrhea after initiation of treatment was 2.5 (1.5) days in the placebo group (n = 25) vs. 1.9 (0.9) days in the small dosage (n = 20) and 1.5 (1.1) days in the large dosage (n = 21) L. reuteri recipients (P = 0.01). By the second day of treatment watery diarrhea persisted in 80% of the placebo, 70% of the small dosage and 48% of the large dosage L. reuteri recipients (P = 0.04, large dosage vs. placebo). Stool cultures for lactobacilli confirmed that administration of L. reuteri resulted in good colonization of the GI tract. The mean (+/-SD) of total Lactobacillus count 2 days after treatment initiation was 2.8 (1.6) log 10 cfu/g in the placebo group, 4.5 (2.0) log 10 cfu/g in the small dosage L. reuteri group and 6.1 (1.2) log 10 cfu/g in the large dosage L. reuteri group (P = 0.0004). CONCLUSIONS: L. reuteri effectively colonized the gastrointestinal tract after administration and significantly shortened the duration of watery diarrhea associated with rotavirus. There was a correlation between the dosage of L. reuteri and the clinical effect.

Rapid amplified ribosomal DNA restriction analysis (ARDRA) identification of Lactobacillus spp. isolated from fecal and vaginal samples.

Amplified ribosomal DNA restriction analysis (ARDRA) was used to identify different species of Lactobacillus isolated from human faeces and vagina. PCR-ARDRA was performed using a set of four restriction enzymes, able to differentiate fourteen species of Lactobacillus. The PCR-ARDRA procedure described in this paper was shown to be a reliable and rapid method for identifying Lactobacillus species from intestinal and vaginal microflora at species and subspecies level.

Principles of ex ovo competitive exclusion and in ovo administration of Lactobacillus reuteri.

The data that have been presented indicate that the in ovo use of competitive exclusion (CE) agents is feasible for both chickens and turkeys. However, there are many pitfalls that await the use of in ovo application of CE agents, including the use of nonspecies-specific intestinal microbes and the use of harmful proteolytic, gas-producing and toxin-producing intestinal microbes. Of the potential CE agents that have posthatch application, only Lactobacillus reuteri has been shown to be safe and effective in terms of not affecting hatchability and in having a prolonged effect in the hatched chick or poult. Lactobacillus reuteri administration in ovo increases its rate of intestinal colonization and decreases the colonization of Salmonella and Escherichia coli in both chicks and poults. Additionally, mortality due to in-hatcher exposure to E. coli or Salmonella is reduced with in ovo L. reuteri. Use of antibiotics in ovo may preclude the use of co-administered CE agents, but Gentamicin and L. reuteri are a compatible mixture when administered in ovo in separate compartments. Nevertheless, the intestinal morphology can be affected by both the CE agent and by antibiotics. Lactobacillus reuteri both in ovo and ex ovo will increase villus height and crypt depth, and Gentamicin in ovo causes a shortening and blunting of the villus. Both Gentamicin and L. reuteri in ovo suppress potentially pathogenic enteric microbes, but with diminished antibiotic effects shortening and blunting of the intestinal villi does not correct itself. Goblet cell numbers increase significantly on the ileum villus of chicks treated with Gentamicin in ovo, and this is presumably due to the increase in potentially pathogenic bacteria in the intestinal tract. Diminishing antibiotic effects posthatch would then negatively affect the absorption of nutrients and reduce growth at least in a transitory manner. Thus, L reuteri administration in ovo singly or in combination with Gentamicin followed by L reuteri via drinking water or feed appears to have potential to control many enteric pathogens in poultry. Additional work in the use of in ovo CE cultures is mandated because there is a world-wide movement to reduce antibiotic use in poultry due to increased microbial resistance to antibiotics. Use of naturally occurring intestinal bacterial cultures, either in mixed culture or as single well-defined cultures, has potential for immediate use in the poultry industry.

Atypical Escherichia coli strains and their association with poult enteritis and mortality syndrome.

To date, no definitive etiology has been described for Poult Enteritis and Mortality Syndrome (PEMS). However, two atypical Escherichia coli colony types are isolated consistently from moribund and dead poults afflicted with PEMS. To test the infectivity of these E. coli strains, poults were placed into floor pens in three isolation treatment rooms: 1) CONTROL: no bacterial challenge, 2) E. coli colony Types 1 or 2 posthatch oral challenge: 10(8) cfu/per poult at 1 d, and 3) E. coli colony Types 1 or 2 posthatch oral challenge: 10(8) cfu/per poult at 6 d. Daily intramuscular injections of cyclophosphamide (100 micrograms per poult) from 1 to 5 d posthatch were given to half of the poults in each treatment. Atypical E. coli challenge caused BW depression, and cyclophosphamide treatment exacerbated the response. All E. coli-challenged poults developed diarrhea similar to PEMS. Mortality was increased by both atypical E. coli colony types, but at 21 d E. coli colony Type 2 caused greater mortality than colony Type 1. With cyclophosphamide treatment, mortality was exacerbated with both colony types, but colony Type 2 at 1 d caused the greatest mortality. Ultrastructural damage to ileum epithelium cell microvilli and subcellular organelles indicated that part of the BW depression could be attributed to malabsorption of nutrients. It was concluded that the atypical E. coli colony Types 1 and 2 play a significant role in the PEMS disease.

Characterization of two Escherichia coli isolates associated with poult enteritis and mortality syndrome.

Two colonial types (1 and 2) of Escherichia coli are represented predominantly in cultures isolated from turkey poults with poult enteritis and mortality syndrome (PEMS). Biotype codes determined using two systems (BBL: 36570 and 34560 for colony types 1 and 2, respectively; API-20E: 5144572 and 5144512 for colony types 1 and 2, respectively) clearly establish these organisms as E. coli. These isolates were not clearly divergent from the general profile for E. coli, but colony type 2 differs from colony type 1 with regard to its negative reactions for ornithine decarboxylase and the fermentation of dulcitol, rhamnose, sucrose, and melibiose, suggesting that it is atypical. Colony type 1 is nonserotypable and nonmotile, whereas colony type 2 is serotyped as O136: motile because it has H antigens associated with flagella. Capsular antigens were not found, but thin capsules were seen on cells from both colony types in stained preparations. Cultural morphology was different with colony type 1 having a circular, mucoid, raised morphology and colony type 2 having an irregular, flat, rough morphology. Colony type 1 has a doubling time at 37 C of about 20 min, whereas colony type 2 doubles in 30 min. Furthermore, colony type 1 is a potent colicin producer, but colony type 2 is not a colicin producer. Both E. coli isolates have resistance profiles for multiple antibiotics. Each strain responds to third generation fluoroquinolone antibiotics by changing their biotypes and become resistant after culturing once in their presence. These E. coli are proposed as possible etiological links in the complex series of events that take place in poults susceptible to PEMS.

Dependence of protease secretion by Streptococcus faecalis var. liquefaciens on arginine and its possible relation to site of synthesis.

Washed cells of Streptococcus faecalis var. liquefaciens, when harvested from media that supported protease biosynthesis, continued to release this extracellular enzyme in phosphate buffer. The addition of ethylenediaminetetraacetic acid (EDTA) halted the secretion. If zinc ions were added to the EDTA-treated cells before 45 to 60 min had elapsed, a fraction of the anticipated enzyme activity was observed. After 60 min, arginine and phosphate, in addition to zinc, were necessary for the demonstration of proteolytic activity. The enzyme that was released was newly formed, because chloramphenicol, puromycin, or actinomycin D prevented its appearance. Energy for this synthetic reaction was obtained, apparently, from arginine; lactose could not be substituted for arginine. This last point is interpreted to mean that extracellular protease biosynthesis occurs in a localized area or cellular compartment into which the adenosine triphosphate derived from the fermentation of lactose cannot diffuse. No evidence was found for a protease zymogen, although this possibility is not completely precluded.

Formation, regeneration, and transfection of Lactobacillus plantarum protoplasts.

Protoplasts of L. plantarum were produced by mutanolysin-lysozyme digestion at 50 degrees C and regenerated at a frequency of 1.6 to 3.8%. The addition of Tween 80 to the growth medium increased the length of time required for protoplast formation. When transfected with bacteriophage B2 DNA, transfection efficiencies ranged from 25 to 230 PFU/microgram of DNA and from 2.2 X 10(-5) to 4.7 X 10(-4) PFU per recovered protoplast. Total transfectant yield was 3.7 X 10(2) to 3.4 X 10(3) per treatment. Transformations with plasmid DNA were unsuccessful.

Exclusion of vanA, vanB and vanC type glycopeptide resistance in strains of Lactobacillus reuteri and Lactobacillus rhamnosus used as probiotics by polymerase chain reaction and hybridization methods.

Strains of Lactobacillus reuteri and Lact. rhamnosus are used as probiotics in man and animal. The aim of this study was to determine whether the glycopeptide resistance in these lactobacilli has a similar genetic basis as in enterococci. Five Lact. reuteri strains and one Lact. rhamnosus, as well as four Enterococcus control strains, were probed for the vanA gene cluster, the vanB gene and the vanC gene by PCR and Southern hybridization, and DNA/DNA hybridization. Their resistance and plasmid patterns were also investigated. All Lactobacillus strains were resistant to vancomycin but susceptible to a broad range of antibiotics. Four of the Lactobacillus strains (including the Lact. rhamnosus strain) did not harbour any plasmid and two of them contained five and 6 plasmid bands respectively. None of the Lactobacillus strains possessed the vanA, vanB or vanC gene. These findings indicate that the glycopeptide resistance of the Lactobacillus strains analysed is different from the enterococcal type. The study provides reassurance on the safety of the Lactobacillus strains used as probiotics with regard to their vancomycin resistance.

Lactobacillus reuteri as a therapeutic agent in acute diarrhea in young children.

BACKGROUND: Certain strains of lactobacilli may promote recovery from acute diarrhea. Lactobacillus reuteri is of human origin and is a natural colonizer of gastrointestinal tract. In this trial, exogenously administered L. reuteri was studied as a therapeutic agent in acute diarrhea. METHODS: Forty patients between 6 and 36 months of age hospitalized with acute diarrhea (75% rotavirus) were studied. After parental consent, the patients were randomized to one of two treatment groups to receive either 10(10) to 10(11) colony-forming units of L. reuteri or a matching placebo daily for the length of hospitalization or up to 5 days. The clinical outcome of diarrhea and colonization of L. reuteri were evaluated. RESULTS: The mean (SD) duration of watery diarrhea after treatment was 1.7 (1.6) days in the L. reuteri group and 2.9 (2.3) days in the placebo group (p = 0.07). On the second day of treatment only 26% of patients receiving L. reuteri had watery diarrhea, compared with 81% of those receiving placebo (p = 0.0005). Cultures of lactobacilli from stool samples demonstrated that administration of L. reuteri resulted in colonization of the gastrointestinal tract. Lactobacillus reuteri accounted for > 75% of the total lactobacilli found in children fed with this product. CONCLUSIONS: Lactobacillus reuteri is effective as a therapeutic agent in acute rotavirus diarrhea in children. Further studies are warranted to confirm the present finding and to explore the full therapeutic potential of L. reuteri in acute viral diarrhea.

Production and isolation of reuterin, a growth inhibitor produced by Lactobacillus reuteri.

Lactobacillus reuteri is a prominent member of the Lactobacillus population in the gastrointestinal ecosystem of humans, poultry, swine, and other animals. Reuterin is a newly discovered, broad-spectrum antimicrobial substance produced by this species during fermentation of glycerol. In this report, we describe procedures for (i) producing reuterin in sufficient amounts to isolate from a fermentation mixture and (ii) isolating this substance by high-performance liquid chromatography. By using uniformly labeled [14C]glycerol, reuterin was identified as a product of glycerol fermentation associated with the production of beta-hydroxypropionic acid and trimethylene glycol.