Perioperative synbiotic treatment to prevent postoperative infectious complications in biliary cancer surgery: a randomized controlled trial

SUMMARY BACKGROUND DATA

Use of synbiotics has been reported to benefit human health, but clinical value in surgical patients remains unclear.

OBJECTIVE

To investigate the effect of perioperative oral administration of synbiotics upon intestinal barrier function, immune responses, systemic inflammatory responses, microflora, and surgical outcome in patients undergoing high-risk hepatobiliary resection.

METHODS

Patients with biliary cancer involving the hepatic hilus (n = 101) were randomized before hepatectomy, into a group receiving postoperative enteral feeding with synbiotics (group A); or another receiving preoperative plus postoperative synbiotics (group B). Lactulose-mannitol (L/M) ratio, serum diamine oxidase (DAO) activity, natural killer (NK) cell activity, interleukin-6 (IL-6), fecal microflora, and fecal organic acid concentrations were determined before and after hepatectomy. Postoperative infectious complications were recorded.

RESULTS

Of 101 patients, 81 completed the trial. Preoperative and postoperative changes in L/M ratio and DAO activity were similar between groups. Preoperatively in group B, NK activity, and lymphocyte counts increased, while IL-6 decreased significantly (P < 0.05). Postoperative serum IL-6, white blood cell counts, and C-reactive protein in group B were significantly lower than in group A (P < 0.05). During the preoperative period, numbers of Bifidobacterium colonies cultured from and total organic acid concentrations measured in feces increased significantly in group B (P < 0.05). Postoperative concentrations of total organic acids and acetic acid in feces were significantly higher in group B than in group A (P < 0.05). Incidence of postoperative infectious complications was 30.0% (12 of 40) in group A and 12.1% (5 of 41) in group B (P < 0.05).

CONCLUSIONS

Preoperative oral administration of synbiotics can enhance immune responses, attenuate systemic postoperative inflammatory responses, and improve intestinal microbial environment. These beneficial effects likely reduce postoperative infectious complications after hepatobiliary resection for biliary tract cancer.

Survival of Lactobacillus casei in the human digestive tract after consumption of fermented milk

A human trial was carried out to assess the ileal and fecal survival of Lactobacillus casei DN-114 001 ingested in fermented milk. Survival rates were up to 51.2% in the ileum and 28.4% in the feces. The probiotic bacterium has the capacity to survive during its transit through the human gut.

Cariogenic Bacteria and Caries Risk in Elderly Japanese Aged 80 and Older with at Least 20 Teeth

OBJECTIVES

To assess caries risk and check the presence of four commonly found oral cariogenic bacteria in "8020" achievers.

DESIGN

Initial report based on Japan's newly implemented "8020" campaign, which aims to promote health and awareness in older people. Simply stated, the goal is, at 80 years, to maintain 20 teeth.

SETTING

Healthy community-dwelling elderly individuals of Okayama Prefecture, Japan.

PARTICIPANTS

One hundred sixty individuals aged 80 and older with 20 of their own natural teeth.

MEASUREMENTS

General and oral health conditions, caries risk assessment using the Cariostat method, and polymerase chain reaction (PCR) detection of four oral cariogenic bacteria.

RESULTS

The participants had an average of 24.7 teeth, of which 12.1 were sound, 12.2 were treated, and 0.4 were untreated. Based on Cariostat scores, 64.4% had low caries risk. Using PCR, Streptococcus mutans, S. sobrinus, Lactobacillus casei, and L. plantarum were detected in 51.3%, 23.1%, 40%, and 25% of the participants, respectively. S. mutans (P<.001), S. sobrinus (P=.002), L. casei (P<.001), and L. plantarum (P=.001) deoxyribonucleic acid band was detected more in participants with high caries risk scores.

CONCLUSION

Participants with low caries risk scores had low prevalence of cariogenic bacteria, 20 or more sound teeth, and fewer missing teeth. Incorporating caries risk assessment, using the Cariostat and PCR analysis, in the "8020" campaign in health systems worldwide will contribute to a better life for the aging society, initiate research interest regarding the program, and improve current health policies.

Use of polymerase chain reaction techniques and sodium dodecyl sulfate-polyacrylamide gel electrophoresis for differentiation of oral Lactobacillus species

BACKGROUND/AIMS

The genus Lactobacillus has been associated with dental caries in humans, although it is seldom speciated due to lack of simple and nonlaborious identification methods. A considerable heterogeneity among Lactobacillus species has been demonstrated. The purpose of this study was to develop simple methods combining restriction fragment length polymorphism analysis of polymerase chain reaction (PCR)-amplified 16S rRNA (16S rRNA gene PCR-RFLP) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for the identification of 13 reference strains of Lactobacillus.

METHODS

The 16S rRNA gene sequences were amplified by PCR using universal primers and digestion of PCR products with the restriction endonucleases, HpaII and HaeIII. The 16S rRNA gene PCR-RFLP is reproducible and has been proved to be useful for differentiating Lactobacillus strains to species level. Seventy-seven Lactobacillus isolates from a Thai population were used to show the applicability of the identification test.

RESULTS

PCR-RFLP alone had limitations, because the RFLP patterns of Lactobacillus casei and Lactobacillus rhamnosus and of Lactobacillus acidophilus and Lactobacillus crispatus showed similar patterns; however, these could be differentiated by SDS-PAGE. Of the 77 isolates, 38 were identified as Lactobacillus fermentum, 25 as L. rhamnosus, 5 as Lactobacillus salivarius, 5 as L. casei, 3 as L. acidophilus and 1 as Lactobacillus plantarum.

CONCLUSION

16S rRNA gene PCR-RFLP, using HpaII and HaeIII, together with SDS-PAGE protein profiles could be an alternative method for the identification of oral Lactobacillus strains to species level, and may be applicable for large-scale studies on the association of Lactobacillus to dental caries.

Oral immunoadjuvant activity of Lactobacillus casei subsp. casei in dextran-fed layer chickens

We recently reported that synbiotic Lactobacillus casei subsp. casei together with specific substrate dextran elicited an enhancement in humoral immune response against bovine serum albumin (BSA) as a model antigen in BALB/c mice. The present study was designed to evaluate the oral immunoadjuvant effects of the synbiotic in layer chickens. Using a PCR assay, L. casei subsp. casei was detected specifically in the intestinal chyme of chickens (10 d of age, Julia strain) fed ad libitum on a diet supplemented with 75 mg dextran/kg (dextran-supplemented diet, DSD) and administered orally with 10(7) colony-forming units (CFU) L. casei subsp. casei in 0.1 ml PBS with the aid of an intubation needle at 1, 2 and 3 d of age. Furthermore, oral administration of 10(7) CFU L. casei subsp. casei at 1-3 d of age significantly enhanced the production of anti-BSA antibody in DSD-fed chickens (60 d of age) administered orally with 1 mg BSA at 32 and 33 d of age and subcutaneously with 5 microg BSA at 33 d of age. In addition, among bacterial numbers tested, 10(6) CFU L. casei subsp. casei together with dextran induced an effective increase in humoral immune response to mixed inactivated vaccines against Newcastle disease and avian infectious bronchitis, and the treatment may be advantageous in protecting against these infectious diseases in chickens in actual application. These results suggest that dietary supplementation of L. casei subsp. casei with dextran leads to immunomodulation of humoral immune responses.

Effects of orally administered Lactobacillus casei DN-114 001 on the composition or activities of the dominant faecal microbiota in healthy humans

The composition and activities of the faecal microbiota in twelve healthy subjects analysed in a single open study were monitored before (1-week baseline step), during (10 d supplementation step) and after (10 d follow-up step) the ingestion of a fermented milk containing Lactobacillus casei DN-114 001. Fluorescent in situ hybridisation with group-specific DNA probes, real-time PCR using L. paracasei group-specific primers and temporal temperature gradient gel electrophoresis (TTGE) using group-specific primers were carried out, together with bacterial enzyme activity and metabolite analyses to monitor the structure and activities of the faecal microbiota. L. casei DNA was detected in the faeces of all of the subjects by TTGE after 10 d supplementation. Its quantification by real-time PCR showed a 1000-fold increase during the test step compared with initial levels. No major modification in either the dominant members of the faecal microbiota or their activities was observed during the trial. In conclusion, the short-term consumption of a milk product containing L. casei DN-114 001 was accompanied by a high, transient increase in the quantity of this strain in the faeces of all of the subjects without markedly affecting biochemical or bacteriological factors.

Clinical safety of Lactobacillus casei shirota as a probiotic in critically ill children

OBJECTIVE

Diarrhea is frequently observed among critically ill children (CIC) admitted for intensive care. There is increasing evidence that probiotics decrease the incidence of acute infectious and nosocomial and antibiotic induced diarrhea amongst children hospitalized in nonintensive care settings. Despite theoretic advantages for the use of probiotics in CIC, safety has remained a concern in this vulnerable group. The objective of this study was to establish clinical safety (invasive infection/colonization) of Lactobacillus casei shirota (LCS) used as a probiotic in CIC.

METHODS

Prospective, descriptive pilot study on children admitted to a pediatric intensive care unit. Data regarding safety were collected on the initial recruits to a randomized controlled trial aimed to study the effects of LCS on stool frequency and consistency in CIC. Safety was assessed by bacteriologic surveillance for LCS in surface swabs and endotracheal aspirates (colonization) as well as blood, urine, and sterile body fluid cultures (invasive infection/bacteremia).

RESULTS

Safety data were available on 28 patients. LCS was cultured from the feces of five of the six study subjects who opened bowels during their stay on the pediatric intensive care unit. There was no evidence of either colonization or bacteremia with LCS in bacteriologic cultures obtained from study subjects. The preparation was well tolerated with no apparent side effects.

CONCLUSIONS

Our pilot safety study suggests that the use of LCS as a probiotic in enterally fed CIC is safe.

Lactic Acid Bacteria Production From Whey

The main purpose of this work was to isolate and characterize lactic acid bacteria (LAB) strains to be used for biomass production using a whey-based medium supplemented with an ammonium salt and with very low levels of yeast extract (0.25 g/L). Five strains of LAB were isolated from naturally soured milk after enrichment in whey-based medium. One bacterial isolate, designated MNM2, exhibited a remarkable capability to utilize whey lactose and give a high biomass yield on lactose. This strain was identified as Lactobacillus casei by its 16S rDNA sequence. A kinetic study of cell growth, lactose consumption, and titratable acidity production of this bacterial strain was performed in a bioreactor. The biomass yield on lactose, the percentage of lactose consumption, and the maximum increase in cell mass obtained in the bioreactor were 0.165 g of biomass/g of lactose, 100%, and 2.0 g/L, respectively, which were 1.44, 1.11, and 2.35 times higher than those found in flask cultures. The results suggest that it is possible to produce LAB biomass from a whey-based medium supplemented with minimal amounts of yeast extract.

Ribotyping of Lactobacillus casei group strains isolated from dairy products

A series of lactobacilli isolated from dairy products were characterized using biotyping and ribotyping with EcoRI and HindIII restriction enzymes. Biotyping assigned 14 strains as Lactobacillus casei, 6 strains as Lactobacillus paracasei subsp. paracasei and 12 as Lactobacillus rhamnosus. The obtained ribotype patterns separated all analyzed strains into two clearly distinguished groups corresponding to L. rhamnosus and L. casei/L. paracasei subsp. paracasei. The HindIII ribotypes of individual strains representing these two groups were visually very similar. In contrast, EcoRI ribotyping revealed high intraspecies variability. All ribotypes of L. casei and L. paracasei subsp. paracasei dairy strains were very close and some strains even shared identical ribotype profiles. The type strains L. casei CCM 7088T (= ATCC 393T) and Lactobacillus zeae CCM 7069T revealing similar ribopatterns formed a separate subcluster using both restriction enzymes. In contrast, the ribotype profile of L. casei CCM 7089 (= ATCC 334) was very close to ribopatterns obtained from the dairy strains. These results support synonymy of L. casei and L. paracasei species revealed by other studies as well as reclassification of the type strain L. casei CCM 7088T as L. zeae and designation of L. casei CCM 7089 as the neotype strain.

Oral lactobacilli in chronic periodontitis and periodontal health: species composition and antimicrobial activity

BACKGROUND/AIMS

Lactobacilli are known to play an important role in the maintenance of health by stimulating natural immunity and contributing to the balance of microflora. However, their role in chronic periodontitis is unclear. We aimed to identify oral lactobacilli in chronic periodontitis and periodontally healthy subjects, and to determine their antimicrobial activity against putative oral pathogens.

METHODS

A total of 238 Lactobacillus isolates from the saliva and subgingival sites of 20 chronic periodontitis and 15 healthy subjects were collected. In all, 115 strains were identified using rapid amplified ribosomal DNA restriction analysis. Antimicrobial activity against Streptococcus mutans, Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia was assessed.

RESULTS

Lactobacilli belonging to 10 species were identified. The most prevalent strains in healthy persons were Lactobacillus gasseri and Lactobacillus fermentum and in chronic periodontitis patients, Lactobacillus plantarum. Obligately homofermentatives, particularly L. gasseri, were less prevalent in chronic periodontitis patients compared with healthy subjects (8% vs. 64% for L. gasseri, P < 0.01). Sixty-nine percent of tested lactobacilli inhibited S. mutans, 88% A. actinomycetemcomitans, 82% P. gingivalis and 65% P. intermedia. The strongest antimicrobial activity was associated with Lactobacillus paracasei, L. plantarum, Lactobacillus rhamnosus, and Lactobacillus salivarius. The strains from periodontally healthy patients showed a lower antimicrobial activity against S. mutans than the strains from chronic periodontitis patients.

CONCLUSION

The composition of oral lactoflora in chronic periodontitis and healthy subjects differs, with a higher prevalence of homofermentative lactobacilli, particularly L. gasseri, in the latter group. Both homo- and heterofermentative oral lactobacilli suppress the growth of periodontal pathogens, but the antimicrobial properties are strain, species and origin specific.

In situ and non-invasive detection of specific bacterial species in oral biofilms using fluorescently labeled monoclonal antibodies

Noninvasive in situ detection of suspected cariogenic bacterial species within dental biofilms could facilitate monitoring of the dynamic change of oral microbial flora and assist in the assessment of the treatment efficacy of therapeutic agents. In this study, we explore the possibility to use three well-characterized monoclonal antibodies (MAbs) against Streptococcus mutans, Actinomyces naeslundii, and Lactobacillus casei to identify these three important members of the oral microbial community in the complex environment of oral biofilms. These MAbs, which were conjugated to different fluorescent labels and visualized with confocal laser scanning microscopy (CLSM), proved to be an useful tool to identify the three species of interest (S. mutans, A. naeslundii, and L. casei) under various experimental conditions including in vitro and in vivo derived oral biofilms. Manifold addition of the MAbs on consecutive days did not alter the biofilm structure thus allowing monitoring of the same biofilm over extended time periods. Using this MAb-based method the effect of sucrose challenge on the biofilm composition and the distribution of S. mutans, A. naeslundii, and L. casei were examined. S. mutans was found to be the predominant species under the various biofilm conditions tested. These studies indicate that MAbs based bacterial detection with CLSM is a versatile tool which permits new insights into the ecology of oral biofilm development.

Lactobacillus casei improves resistance to pneumococcal respiratory infection in malnourished mice

We studied the effect of Lactobacillus casei CRL 431 used as a supplement in a repletion diet on the resistance to Streptococcus pneumoniae respiratory infection in malnourished mice. Weaned mice were malnourished after they consumed a protein-free diet (PFD) for 21 d. Malnourished mice were fed a balanced conventional diet (BCD) with or without supplemental L. casei for 7, 14, or 21 consecutive days, or BCD for 7 d with L. casei supplementation on d 6 and 7 (7dBCD+2dLc). The malnourished control (MNC) group was fed only the PFD, whereas well-nourished control (WNC) mice consumed the BCD ad libitum. Mice were challenged with S. pneumoniae at the end of each dietary treatment. Lung colonization and bacteremia were significantly greater in MNC than in WNC. Normalization of the immune response occurred in malnourished mice fed the BCD for 21 d. L. casei supplementation reduced the time required for a normal response from 21 to 7 d. Mice administered the 7dBCD+2dLc repletion treatment had a more effective pathogen clearance from blood and significantly lower lung damage than MNC. This treatment improved both the number of leukocytes and neutrophils in blood and bronchoalveolar lavages (BAL) and the bactericidal function of phagocytic cells to levels that did not differ from those of WNC. In the 7dBCD+2dLc mice, antipneumococcal IgA in BAL was higher than in WNC, whereas antipneumococcal IgG in serum and BAL did not differ. This study suggests that the addition of L. casei to the repletion diet has a beneficial effect because it accelerates the recovery of the innate immune response and improves the specific immune mechanisms against an S. pneumoniae respiratory infection in malnourished mice.

Initiation of protein synthesis by a labeled derivative of the Lactobacillus casei DN-114 001 strain during transit from the stomach to the cecum in mice harboring human microbiota

Although studies on the survival of bacteria in the digestive tract have been reported in the literature, little data are available on the physiological adaptation of probiotics to the digestive environment. In previous work, a transcriptional fusion system (i.e., luciferase genes under the control of a deregulated promoter) was used to demonstrate that a derivative of the Lactobacillus casei DN-114 001 strain, ingested in a fermented milk and thus exhibiting initially a very weak metabolic activity, synthesized proteins de novo after its transit in the digestive tract of mice harboring human microbiota (known as human-microbiota-associated mice). With the same genetic system and animal model, we here investigate for the first time the ability of L. casei to reinitiate synthesis in the different digestive tract compartments. In this study, most ingested L. casei cells transited from the stomach to the duodenum-jejunum within 1 h postingestion. No luciferase activity was observed in these digestive tract compartments after the first hour. At later times, the bulk of bacteria had transited to the ileum and the cecum. Luciferase synthesis was detected between 1.5 and 2.0 h postingestion at the ileal level and from 1.5 h to at least 6.0 h postingestion in the cecum, where the activity remained at a maximum level. These results demonstrate that ingested L. casei (derivative of the DN-114 001 strain) administered via a fermented milk has already reinitiated protein synthesis when it reaches the ileal and cecal compartments.

Isolation and characterization of lactobacilli from some traditional fermented foods and evaluation of the bacteriocins

Lactic acid bacteria (LAB) commonly used in food as starter cultures are known to produce antimicrobial substances such as bacteriocins and have great potential as food biopreservatives. LAB isolated from traditional fermented foods (appam batter and pickles) were screened for bacteriocin production. Two lactobacilli, LABB and LABP (one from each source) producing bacteriocins were characterized. Both the bacilli were homo-fermentative, catalase negative and micro-aerophilic in nature. LABB was found to be a thermobacterium growing at 45 degrees C while LABP was a streptobacterium growing at 15 degrees C. Both were able to grow at pH 4.5-8.6 but were intolerant to high salt concentration. They failed to produce gas from glucose as well as ammonia from arginine. Among the sugars examined they could not ferment arabinose, raffinose, rhamnose or xylose. Additionally, LABB could not ferment esculin, gluconate or mannose. LABB is identified as Lactobacillus acidophilus while LABP as Lb. casei. Their bacteriocins showed a broad inhibitory spectrum against the indicator organisms tested. They were active below pH 8.0 and after autoclaving as well. There was a complete loss of activity when treated with proteolytic enzymes such as trypsin indicating the proteinaceous nature of the active molecules. SDS-PAGE of partially purified bacteriocins indicated the molecular mass of the bacteriocin as 3.8 and 4.5 kDa for LABB and LABP respectively.

Transition of the probiotic bacteria, Lactobacillus casei strain Shirota, in the gastrointestinal tract of a pig

The transition of probiotic bacteria Lactobacillus in the gastrointestinal tract was investigated in pigs that received commercially available fermented milk prepared with Lactobacillus casei strain Shirota (LCS). Three female pigs fistulated at the cecum were fed 130 ml of fermented milk that contained over 10(10) (cfu) LCS with their daily meal for 8 days. Cecal contents were sampled through a fistula every 2 h for 24 h after marker dosing. The viable cell number (log cfu/g) of LCS and the concentrations of transit markers in each sample were determined. The viable number of LCS cells ranged from 3.56 to 6.58. The number of LCS in the cecum was not stable in pigs and varied with the flow of the cecal content. The viable number of LCS cells was significantly correlated with the relative concentration of the marker. These results indicated that most LCS moved with the liquid component. The level of LCS reached the maximum (6.38) 6 h after dosing. Four doses every 6 h may be required to maintain the maximum level of LCS at the cecum.

Case of aortic endocarditis caused by Lactobacillus casei

A case of Lactobacillus aortic valve endocarditis in a 53-year-old immunocompetent patient with past history of rheumatic fever is reported. Clinical symptoms began after a dental extraction and the patient's diet included several yogurts per day. Blood, bone marrow cultures and the replaced aortic valve were positive for Lactobacillus: The clinical isolate was identified as Lactobacillus casei by 16S rDNA sequencing.

Lactobacillus casei, dominant species in naturally fermented Sicilian green olives

This study investigated the phenotypic and genotypic characteristics of lactic acid bacteria in naturally fermented green olives, collected from different areas of Sicily. Both classical biochemical tests and PCR/Restriction Fragments Length Polymorphism (RFLP) of 16S rDNA were used to characterize the isolates. The identity of the isolates was obtained by the partial sequencing analysis of the 16S rDNA. The BioMerieux software assigned the 13 heterofermentative strains to the Lactobacillus brevis species; 24 homofermentative strains were classified as Lactobacillus casei and the remaining 11 homofermentative lactobacilli were identified as Lactobacillus plantarum. The rapid ID 32 STREP test identified coccal-shaped strains as Enterococcus faecium species. The PCR/RFLP analysis showed a remarkable bacterial heterogeneity within the isolates. The 16S rDNA partial sequencing did not confirm biochemical identification, revealing a strong dominance of isolates belonging to the L. casei species. It is noteworthy that this species has never been reported as dominant species in fermented vegetables.A combination of molecular and biochemical analysis allowed the identification of species involved in natural food fermentations.

Use of Group-Specific and RAPD-PCR Analyses for Rapid Differentiation of Lactobacillus Strains from Probiotic Yogurts

The increasing interest in probiotic lactobacilli implicates the requirement of techniques that allow a rapid and reliable identification of these organisms. In this study, group-specific PCR and RAPD-PCR analyses were used to identify strains of the Lactobacillus casei and Lactobacillus acidophilus groups most commonly used in probiotic yogurts. Group-specific PCR with primers for the L. casei and L. acidophilus groups, as well as L. gasseri/johnsonii, could differentiate between 20 Lactobacillus strains isolated from probiotic yogurts and assign these into the corresponding groups. For identification of these strains to species or strain level, RAPD profiles of the 20 Lactobacillus strains were compared with 11 reference strains of the L. acidophilus and L. casei group. All except one strain could be attributed unambigously to the species L. acidophilus, L. johnsonii, L. crispatus, L. casei, and L. paracasei. DNA reassociation analysis confirmed the classification resulting from the RAPD-PCR.

Influence of Adjunct Use and Cheese Microenvironment on Nonstarter Bacteria in Reduced-Fat Cheddar-Type Cheese

This study investigated population dynamics of starter, adjunct, and nonstarter lactic acid bacteria (NSLAB) in reduced-fat Cheddar and Colby cheese made with or without a Lactobacillus casei adjunct. Duplicate vats of cheese were manufactured and ripened at 7 degrees C. Bacterial populations were monitored periodically by plate counts and by DNA fingerprinting of cheese isolates with the random amplified polymorphic DNA technique. Isolates that displayed a unique DNA fingerprint were identified to the species level by partial nucleotide sequence analysis of the 16S rRNA gene. Nonstarter biota in both cheese types changed over time, but populations in the Colby cheese showed a greater degree of species heterogeneity. The addition of the L. casei adjunct to cheese milk at 10(4) cfu/ml did not completely suppress "wild" NSLAB populations, but it did appear to reduce nonstarter species and strain diversity in Colby and young Cheddar cheese. Nonetheless, nonstarter populations in all 6-mo-old cheeses were dominated by wild L. casei. Interestingly, the dominant strains of L. casei in each 6-mo-old cheese appeared to be affected more by adjunct treatment and not cheese variety.

Extent of genetic lesions of the arginine and pyrimidine biosynthetic pathways in Lactobacillus plantarum, L. paraplantarum, L. pentosus, and L. casei: prevalence of CO(2)-dependent auxotrophs and characterization of deficient arg genes in L. plantarum

Lactic acid bacteria require rich media since, due to mutations in their biosynthetic genes, they are unable to synthesize numerous amino acids and nucleobases. Arginine biosynthesis and pyrimidine biosynthesis have a common intermediate, carbamoyl phosphate (CP), whose synthesis requires CO(2). We investigated the extent of genetic lesions in both the arginine biosynthesis and pyrimidine biosynthesis pathways in a collection of lactobacilli, including 150 strains of Lactobacillus plantarum, 32 strains of L. pentosus, 15 strains of L. paraplantarum, and 10 strains of L. casei. The distribution of prototroph and auxotroph phenotypes varied between species. All L. casei strains, no L. paraplantarum strains, two L. pentosus strains, and seven L. plantarum strains required arginine for growth. Arginine auxotrophs were more frequently found in L. plantarum isolated from milk products than in L. plantarum isolated from fermented plant products or humans; association with dairy products might favor arginine auxotrophy. In L. plantarum the argCJBDF genes were functional in most strains, and when they were inactive, only one gene was mutated in more than one-half of the arginine auxotrophs. Random mutation may have generated these auxotrophs since different arg genes were inactivated (there were single point mutations in three auxotrophs and nonrevertible genetic lesions in four auxotrophs). These data support the hypothesis that lactic acid bacteria evolve by progressively loosing unnecessary genes upon adaptation to specific habitats, with genome evolution towards cumulative DNA degeneration. Although auxotrophy for only uracil was found in one L. pentosus strain, a high CO(2) requirement (HCR) for arginine and pyrimidine was common; it was found in 74 of 207 Lactobacillus strains tested. These HCR auxotrophs may have had their CP cellular pool-related genes altered or deregulated.

Production and characterization of species-specific monoclonal antibodies against Actinomyces naeslundii and Lactobacillus casei

Dental caries is a disease induced by a few cariogenic bacterial species. Quantitative detection of these cariogenic bacteria could provide useful information for caries risk assessment. In this study, we developed highly species-specific monoclonal antibodies (MAbs) against the type strains of Actinomyces naeslundii ATCC 12104 and Lactobacillus casei ATCC 11578. Assayed with immunoprecipitation and immunofluorescent microscopy, these antibodies showed high sensitivities and specificities in detecting A. naeslundii and L. casei in saliva. Examining 100 saliva samples using these MAb-based techniques, we found that the number of A. naeslundii in saliva ranges from 0.5 x 10(4) to 4.8 x 10(5) and that the number of L. casei in saliva ranges from 1 x 10(4) to 1.2 x 10(6). With fluorescent imaging techniques and confocal laser scanning microscopy (CLSM), these antibodies were used to visualize A. naeslundii and L. casei within dental plaques derived from stimulated whole human saliva in vitro. The study demonstrated that these MAbs were also able to effectively detect A. naeslundii and L. casei in plaque.

Molecular diagnosis of endocarditis due to Lactobacillus casei subsp. rhamnosus

We report a case of endocarditis due to Lactobacillus casei subsp. rhamnosus. The bacterium isolated from blood cultures and from valve tissue specimens was identified using both phenotypical analysis and DNA sequence analysis, which revealed that the rod profiles of the pathogens recovered from blood cultures and valve tissue specimens were the same.

Lactobacillus casei subsp. rhamnosus sepsis in a patient with ulcerative colitis

Lactobacillus species are part of normal gastrointestinal flora and are an uncommon cause of bacteremia. Lactobacillus casei subsp. rhamnosus was repeatedly isolated in the blood cultures of a 43-year-old woman with ulcerative colitis. Lactobacillus spp. could be considered a potential opportunistic pathogen whenever there is disruption of the physiologic architecture of the intestinal mucosa, such as in abdominal surgery, endoscopic procedures, or enteric pathologies. Clinicians and clinical microbiologists need to be aware of this infective complication in patients with ulcerative colitis.