Antibiotic Susceptibility of Lactobacillus and Bifidobacterium Species from the Human Gastrointestinal Tract

One hundred and twenty-two strains of Bifidobacterium and Lactobacillus species have been tested against 12 antibiotics and two antibiotic mixtures by a commercial system (Sensititre Anaero3; Treck Diagnostic Systems). The upper limits of some minimum inhibitory concentrations (MICs) were completed on MRS agar plates by the NCCLS procedure. All strains were sensitive to chloramphenicol and imipenem and most of the strains were resistant to metronidazole. Bifidobacteria isolates were susceptible to cefoxitin, whereas about half of the lactobacilli were resistant. Approximately 30% of the Bifidobacterium isolates were resistant to tetracycline, as well as five Lactobacillus strains belonging to four different species. None of the tested Bifidobacterium isolates was resistant to vancomycin, whereas a species-dependent resistance was found among the lactobacilli. Single strains of Bifidobacterium longum, Bifidobacterium pseudocatenulatum, Lactobacillus acidophilus, Lactobacillus rhamnosus, and Lactobacillus brevis were resistant to erythromycin and/or clindamycin. Most of the observed resistances seemed to be intrinsic, but some others could be compatible with transmissible determinants.     

Shotgun mass mapping of Lactobacillus species and subspecies from caries related isolates by MALDI‐MS

A taxonomical study of 90 isolates of lactobacilli isolated from soft and hard carious dentine of 70 deciduous molars is presented. The Lactobacillus strains were determined by shotgun mass mapping (SMM). This method based on MALDI‐MS analysis of Lactobacillus isolates treated with trypsin followed by database comparison against a library of mass spectra derived from 20 reference strains. The SMM method allowed to discriminate different Lactobacillus subspecies. The method was used to analyse Lactobacillus isolates of unknown identity derived from carious dentine. Application of the SMM method to isolates from hard carious dentine revealed a nearly similar distribution of L. paracasei ss paracasei (29%), L. paracasei ss tolerans (32%) and L. casei ss rhamnosus (23%) as dominant subspecies. On the other hand, samples derived from soft carious dentine showed a clear bias only to L. paracasei ss paracasei (60%), whereas L. paracasei ss tolerans (14%) and L. casei ss rhamnosus (12%) were clear minorities. Compared to existent methods, SMM has unique potential for the analysis of Lactobacillus strains on subspecies level.     

Genetic screening of wine‐related enzymes in Lactobacillus species isolated from South African wines

Aims: The objective of this study was to investigate the presence of genes coding for enzymes of oenological relevance in wine Lactobacillus strains isolated from South African grape and wine samples during the 2001 and 2002 harvest seasons. Methods and Results: A total of 120 wine lactobacilli isolates belonging to Lactobacillus plantarum, Lactobacillus hilgardii, Lactobacillus brevis, Lactobacillus pentosus, Lactobacillus paracasei, Lactobacillus sakei and Lactobacillus paraplantarum were genetically screened for enzyme‐encoding genes using PCR with primers specific for β‐glucosidase, protease, esterase, citrate lyase and phenolic acid decarboxylase. The results of PCR screening showed that the Lactobacillus strains possessed different combinations of enzymes and that some strains did not possess any of the enzymes tested. Confirmation analysis with gene sequencing also showed high similarity of genes with those available in GenBank database. Conclusion: In this study, we have demonstrated the existence of genes coding for wine‐related enzymes in wine lactobacilli that could potentially hydrolyse wine precursors to positively influence wine aroma. Significance and Impact of the Study: An expansion of knowledge on the genetic diversity of wine‐associated lactic acid bacteria will enable the selection of novel malolactic fermentation starter cultures with desired oenological traits for the improvement of the organoleptic quality of the wine, and hence wine aroma.     

Screening for lactobacilli with probiotic properties in the infant gut microbiota

Lactobacilli are believed to be beneficial for the human hosts and are currently being evaluated as potentially probiotic bacteria. In this study, Lactobacillus strains were isolated from infant faeces and were examined in vitro for potential probiotic properties. Faecal specimens from 63 healthy, full-term infants were collected at 4, 30 and 90 days after delivery. Seventy-four Lactobacillus strains were isolated and one or more different phenotypes from each infant (n = 44) were selected for further testing. The bacterial isolates were identified mainly as L. gasseri, L. crispatus, Lactobacillus paracasei, L. salivarius, L. fermentum after amplification and sequencing of 16s rRNA gene. The strains were examined for acid and bile tolerance, adhesion to Caco-2 cells, antibiotic susceptibility and antimicrobial activity against selected enteric pathogens. The great majority of the isolated lactobacilli were susceptible to ampicillin, amoxicillin/clavulanic acid, tetracycline, erythromycin, cephalothin, chloramphenicol and rifampicin. Resistance to vancomycin or bacitracin was detected to 34% of the strains. Twenty strains out of forty-four exhibited significant tolerance to bile salts. Those strains were subsequently tested for resistance to low pH conditions (pH 2 and 3). Interestingly, 85% (17 strains) of the tested lactobacilli remained unaffected at pH 3 after 3 h of incubation, 6 strains were found resistant at pH 2 after 1.5 h and only 2 strains found resistant after 3 h of incubation. Two of the strains were able to adhere to Caco-2 cells. In conclusion, two isolates fulfilled the in vitro probiotic criteria and are good candidates for further in vivo evaluation.     

Phenotypic and Genotypic Characterization of Non-Starter Lactic Acid Bacteria in Mature Cheddar Cheese

Non-starter lactic acid bacteria were isolated from 14 premium-quality and 3 sensorially defective mature Irish Cheddar cheeses, obtained from six manufacturers. From countable plates of Lactobacillus-selective agar, 20 single isolated colonies were randomly picked per cheese. All 331 viable isolates were biochemically characterized as mesophilic (i.e., group II) Lactobacillus spp. Phenotypically, the isolates comprised 96.4% L. paracasei, 2.1% L. plantarum, 0.3% L. curvatus, 0.3% L. brevis, and 0.9% unidentified species. Randomly amplified polymorphic DNA (RAPD) analysis was used to rapidly identify the dominant strain groups in nine cheeses from three of the factories, and through clustering by the unweighted pair group method with arithmetic averages, an average of seven strains were found per cheese. In general, strains isolated from cheese produced at the same factory clustered together. The majority of isolates associated with premium-quality cheese grouped together and apart from clusters of strains from defective-quality cheese. No correlation was found between the isomer of lactate produced and RAPD profiles, although isolates which did not ferment ribose clustered together. The phenotypic and genotypic methods employed were validated with a selection of 31 type and reference strains of mesophilic Lactobacillus spp. commonly found in Cheddar cheese. RAPD analysis was found to be a useful and rapid method for identifying isolates to the species level. The low homology exhibited between RAPD banding profiles for cheese isolates and collection strains demonstrated the heterogeneity of the L. paracasei complex.     

Characterization of dominant lactic acid bacteria isolated from São Jorge cheese, using biochemical and ribotyping methods

Aims: To identify, using phenotypic and genotypic methods, the dominant lactic acid bacteria (LAB) present in São Jorge cheese – one of the 11 Portuguese cheeses currently bearing an Appéllation d’Origine Protegée status. Methods and Results: A total of 225 isolates from milk, curd and cheeses throughout ripening were identified to the genus level, 108 to the species level and ten to the strain level. Phenotypic methods indicated that lactobacilli, followed by enterococci, were the dominant bacteria. The most frequently isolated species were Lactobacillus paracasei, Lactobacillus rhamnosus, Enterococcus faecalis and Enterococcus faecium. Ribotyping differentiated three L. paracasei, two E. faecalis and one Lactobacillus plantarum types. Enterococcus spp. exhibited the highest esterase and β-galactosidase activities among all isolates. Conclusions: The dominant LAB in São Jorge cheese are L. paracasei, L. rhamnosus, E. faecalis and E. faecium. Enterococcus likely plays a leading role upon acidification and aroma development in said cheese. Significance and Impact of the Study:  Our results support that a combination of conventional biochemical methods with genotypic methods allows for a thorough characterization and identification of isolates. Despite the limited number of isolates subject to molecular subtyping, a few specific Enterococcus and Lactobacillus strains were found that are promising ones for development of a starter culture. Hence, L. paracasei and E. faecalis are good candidates for a tentative starter culture, designed for manufacturing of São Jorge cheese at large – which takes advantage of actual isolates, in attempts to eventually standardize the quality of said cheese variety.     

Isolation of lactobacilli with probiotic properties from the human stomach

Aims: Recent evidence suggests that the human gastric microbiota is much more diverse than previously thought. The aim of this study was to assess the potential for isolating lactobacilli from the human stomach. Methods and Results: Lactobacilli were selectively cultured from gastric biopsies from 12 patients undergoing routine endoscopy. Lactobacilli were present in four of 12 biopsies. We isolated, in total 10 different strains representing five species (Lactobacillus gasseri, L. fermentum, L. vaginalis, L. reuteri and L. salivarius). The 10 isolates varied greatly in their ability to inhibit the growth of two Gram‐positive bacteria and two Gram‐negative bacteria. Furthermore, the acid and bile resistance profiles of the 10 isolates spanned a wide range. Conclusions: Five different Lactobacillus species were cultured from human gastric biopsies for the first time. Significance and Impact of the Study: Diverse Lactobacillus species are more prevalent in the human stomach than previously recognized, representing an untapped source of bacteria with beneficial probiotic and/or biotechnological properties.     

Detection of Caries-Inducing Microorganisms in Hyposalivated Rats without Infection of Mutans Streptococci

Rampant dental caries was induced in hyposalivated rats fed a high sucrose diet without infection of mutans streptococci, in which increased numbers of lactobacilli and S. aureus were demonstrated in the oral flora. Administration of either penicillin or piperacillin, effective against all isolates of lactobacilli, markedly inhibited the caries induction in these rats, while severe dental caries was induced in hyposalivated rats given vancomycin that is inhibitory against S. aureus. These results suggested that certain lactobacilli might induce dental caries in hyposalivated rats fed a sucrose diet. Three strains of Lactobacillus species isolated from the hyposalivated rats were made resistant to erythromycin. The caries-inducing activity of these erythromycin-resistant lactobacilli was studied in hyposalivated rats giving erythromycin in the drinking water at a concentration of 500 μg/ml. After a 61-day experimental period, severe dental caries was induced in hyposalivated rats infected with L. fermentum TY1R. On the other hand, low caries incidence was found in hyposalivated rats infected with either L. acidophilus TY7R or L. plantarum TY3R. These results indicate that L. fermentum may be one of causative agents of dental caries in hyposalivated rats fed a sucrose diet.     

Use of Conserved Randomly Amplified Polymorphic DNA (RAPD) Fragments and RAPD Pattern for Characterization of Lactobacillus fermentum in Ghanaian Fermented Maize Dough

The present work describes the use of randomly amplified polymorphic DNA (RAPD) for the characterization of 172 dominant Lactobacillus isolates from present and previous studies of Ghanaian maize fermentation. Heterofermentative lactobacilli dominate the fermentation flora, since approximately 85% of the isolates belong to this group. Cluster analysis of the RAPD profiles obtained showed the presence of two main clusters. Cluster 1 included Lactobacillus fermentum, whereas cluster 2 comprised the remaining Lactobacillus spp. The two distinct clusters emerged at the similarity level of <50%. All isolates in cluster 1 showed similarity in their RAPD profile to the reference strains of L. fermentum included in the study. These isolates, yielding two distinct bands of approximately 695 and 773 bp with the primers used, were divided into four subclusters, indicating that several strains are involved in the fermentation and remain dominant throughout the process. The two distinct RAPD fragments were cloned, sequenced, and used as probes in Southern hybridization experiments. With one exception, Lactobacillus reuteri LMG 13045, the probes hybridized only to fragments of different sizes in EcoRI-digested chromosomal DNA of L. fermentum strains, thus indicating the specificity of the probes and variation within the L. fermentum isolates.     

<Emphasis Type="Italic">Lactobacillus</Emphasis> spp. associated with early childhood caries

A group of 69 lactobacilli was isolated from caries lesions and root canals of early childhood caries (ECC) affected children treated in the Department of Pedodontics (Children’s Teaching Hospital, Brno, Czech Republic). Biochemical and physiological properties of all strains were characterized by API 50 CH kit and conventional tube tests. The rep-PCR fingerprinting with the (GTG)₅ primer was used for genotypic grouping of the isolates. The (GTG)₅-PCR fingerprinting grouped all analyzed strains into a few clusters in nearly full agreement with phenotype identification results and clarified the taxonomic position of 13 biochemically unidentified strains. In total, 20 strains of Lactobacillus fermentum, 17 L. rhamnosus, 14 L. casei/paracasei, 7 L. gasseri, 7 L. salivarius and 4 L. plantarum were identified. Mixtures of two or even three Lactobacillus spp. were isolated from a few root canal content samples. Results obtained by biotyping and (GTG)₅-PCR were generally comparable except for L. gasseri strains that were not biochemically identified. The (GTG)₅-PCR fingerprinting was shown to be quicker, easier to perform and more reliable than biotyping. Our results imply this molecular method as a good tool for screening and identification of Lactobacillus spp. inhabiting dental plaque.     

Oral Lactobacillus species in type 2 diabetic patients living in southern Thailand

Although lactobacilli are part of normal oral, gastrointestinal and genitourinary flora, they are an uncommon cause of infections in human. Lactobacillus-associated infections have generally occurred in patients with serious underlying conditions e.g. diabetes and cancer that might favour certain microorganisms. The aim of this study was to characterize species and genotypes of lactobacilli isolated from diabetic patients and non-diabetic subjects. One hundred and five type 2 diabetic patients and 103 non-diabetic subjects were recruited in this study. A total of 170 isolates of Lactobacillus were identified using 16S rRNA gene PCR-RFLP and genotyping were performed using AP-PCR by ERIC primers. It was found that type 2 diabetic patients had a significantly higher prevalence (p = 0.008) and level of lactobacilli than non-diabetic controls (p = 0.030). The most frequently isolated Lactobacillus spp. were L. casei/paracasei and L. fermentum in both the diabetic and non-diabetic groups. Strains of L. casei/paracasei and L. fermentum from between and within individuals were genotyped, and the genotyping of Lactobacillus strains showed diversity between individuals. One up to three genotypes of these two species could be found in the same subject. Interestingly, fewer genotypes were found in the diabetic patients than in the non-diabetic subjects.     

Systematics of theLactobacillus population on rat intestinal mucosa with special reference toLactobacillus reuteri

The systematics of theLactobacillus population of the intestines of 88 different rats was studied; 80 rats had been fed on fermented oat-meal soup (Molin et al. 1992). One-hundred-twenty-twoLactobacillus strains from the intestinal mucosa were phenotypically classified together with twenty-eight reference strains ofLactobacillus andLeuconostoc, using 49 unit characters. Data were examined using Jaccard coefficient, and unweighted pair group algorithm with arithmetic averages. Two major and eleven minor clusters were defined at the 76% S_J-similarity level: Cluster 1 included thirty isolates which could not be identified further, but had resemblance to the type strains ofL. jensenii, L. gasseri, L. crispatus, and to some extent toL. acidophilus. Cluster 12 including fifty-four intestinal isolates was identified asL. reuteri; and so was cluster 13 (five isolates). Isolates of the major clusters were found in all parts of the intestines. The genomic homogeneity of theL. reuteri isolates was scrutinized by endonuclease restriction analysis of the chromosomal DNA, and the isolates could be divided into six genomic strains.     

Antifungal activity of clinical Lactobacillus strains against Candida albicans biofilms: identification of potential probiotic candidates to prevent oral candidiasis

This study isolated Lactobacillus strains from caries-free subjects and evaluated the inhibitory effects directly on three strains of C. albicans, two clinical strains and one reference strain. Thirty Lactobacillus strains were isolated and evaluated for antimicrobial activity against in vitro C. albicans biofilms. L. paracasei 28.4, L. rhamnosus 5.2 and L. fermentum 20.4 isolates exhibited the most significant inhibitory activity against C. albicans. Co-incubation between these microorganisms resulted in deterrence of biofilm development and retardation of hyphal formation. The hindrance of biofilm development was characterized by the downregulated expression of C. albicans biofilm-specific genes (ALS3, HWP1, EFG1 and CPH1). L. paracasei 28.4, L. rhamnosus 5.2 and L. fermentum 20.4 demonstrated the ability to exert antifungal activity through the inhibition of C. albicans biofilms.     

In vitro inhibitory activity of probiotic spore-forming bacilli against genotoxins

Aims: To investigate the ability of bacilli of various species (Bacillus clausii, Bacillus subtilis, Bacillus lentus, Bacillus pumilus. Bacillus megaterium, Bacillus firmus, Bacillus sp.) and origins (probiotic and collection strains) to counteract the activity of some representative DNA‐reactive agents. Methods and Results: The inhibitory effect of 21 bacilli strains, previously characterized by tDNA‐PCR, on four genotoxins, was examined in vitro using the short‐term assay SOS‐Chromotest. All strains had a high inhibitory activity against 4‐nitroquinoline‐1‐oxide and N‐methyl‐N′‐nitro‐nitrosoguanidine (direct agents), whereas the inhibitory activity was high or moderate against 2‐amino‐3,4‐dimethylimidazo[4,5‐f]quinoline and aflatoxin B1 (indirect agents). Antigenotoxicity was observed in vegetative cells, but not heat‐treated cells or spore suspensions. The spectroscopic properties of compounds were modified after cell co‐incubation and all the strains maintained high viability after exposure to the genotoxins. Conclusions: No relevant differences in antigenotoxicity were evidenced among strains of the examined species or between probiotic and collection strains. Significance and Impact of the Study: Although derived from an in vitro model, the results suggest that Bacillus‐based probiotics could be useful for reducing the gastrointestinal risk originating from genotoxic agents.     

Taxonomic Lactobacillus Composition of Feces from Human Newborns during the First Few Days

Abstract Intestinal microbiota comprise a complex ecosystem whose equilibrium is crucial for the health of animal species. For humans, data exist on the microbiota composition in adult subjects, but few studies have addressed the microbiota composition in infants. In particular, data on the presence and species distribution of members of the genus Lactobacillus in newborns (less than one week old) are lacking. In the present work, the feces of healthy newborns were sampled to determine the taxonomic composition of Lactobacillus in the intestinal microbiota in a group of 16 neonates. In total, 1640 colony-forming units (CFU) were isolated, of which 420 grouped in the Lactobacillus genus by means of primary phenotypic characterization. The 420 isolates were further grouped into 125 strains on the basis of identical plasmid profiles. Of these 125 strains, 21 turned out to be permanent, i.e., they were identified in the feces of the same subject on several consecutive days. Sugar fermentation, DNA/DNA hybridization, and S-layer protein determination enabled us to classify 52 of the 125 strains as follows: L. paracasei (40 strains), L. delbrueckii sp. (1 strain), and L. acidophilus (sensu stricto) (11 strains). Based on the same criteria, the remaining 73 strains were tentatively allotted to the Johnson subgroup B, although hybridization experiments with probes specific for L. gasseri and L. johnsonii species were not performed. The presence of new species among these 73 strains cannot be excluded. Surprisingly, the obligately heterofermentative lactobacilli, L. reuteri in particular, were entirely absent from the feces of healthy newborns. Received: 26 March 1997; Accepted: 24 July 1997     

Antimutagenic activity of Lactobacillus plantarum KLAB21 isolated from kimchi Korean fermented vegetables

Antimutagenic activity of Lactobacillus plantarum KLAB21, isolated from Korean kimchi, was investigated against MNNG (N-methyl-N-nitro-N-nitrosoguanidine), NQO (4-nitroquinoline-1-oxide), NPD (4-nitro-O-phenylenediamine) and aflatoxin B1 using Salmonella typhimurium strains TA100 and TA98. Although all the cell fractions including the culture supernatant, dry cells and cell-free extract exhibited antimutagenic activity against MNNG and NQO, the culture supernatant possessed the highest activity. The antimutagenic ratio of the culture supernatant was 98.4% against MNNG on strain TA100 and 57.3% against NQO on strain TA98. Its antimutagenic activity was reconfirmed by a Bacillus subtilis spore-rec assay. Levels of the antimutagenic ratios of other lactic acid bacteria originating from fermented milk ranged between 26.8 to 53% against MNNG and 28.5 to 43.4% against NQO. The antimutagenic activities of the strain KLAB21 against NPD were 72.6% on TA100 and 62.8% on TA98, and those against aflatoxin B1 were 82.5% on TA100 and 78.2% on TA98.     

<Emphasis Type="Italic">In vitro</Emphasis> assessment of immunomodulating activity of the two <Emphasis Type="Italic">Lactobacillus</Emphasis> strains isolated from traditional fermented milk

The objective of this study was to evaluate the in vitro immunomodulating capacity of Lactobacillus coryniformis subsp torquens T3L (L. coryniformis T3L) isolated from traditional fermented yak’s milk in Tibet, China, and Lactobacillus paracasei supsp. paracasei M5L (L. paracasei M5L)isolated from kumiss in Sinkiang, China was used as control. The effects of live bacteria, cell wall and genomic DNA of the two Lactobacillus strains on human peripheral blood mononuclear cells (PBMCs) proliferation, production of interleukin-12 (IL-12 p70), interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α), and natural killer (NK) cell activity were assessed. The live bacteria, cell wall and genomic DNA of the two lactobacilli exerted proliferative effects on PBMCs. Live bacteria at 1 × 10⁶ c.f.u. ml⁻¹, cell wall at 20 μg protein ml⁻¹ and DNA at 50 μg DNA ml⁻¹ of the strainS induced the secretion of IL-12 (p70), IFN-γ and TNF-α by PBMCs. NK cell activities increased after cultivation of PBMCs with live bacteria, cell wall and DNA of the strains. Overall, these results demonstrate that the live bacteria, cell wall and genomic DNA of the two Lactobacillus strains exhibit immunomodulating activity.     

Strain-dependent proliferation in response to human gastric mucin and adhesion properties of Helicobacter pylori are not affected by co-isolated Lactobacillus sp

Background: Helicobacter pylori colonize the mucus layer that covers the gastric epithelium and can cause gastritis, ulcers, and gastric cancer. Recently, Lactobacillus sp. have also been found to reside in this niche permanently. This study compares adhesive properties and proliferation of co‐isolated lactobacilli and H. pylori in the presence of mucins and investigates possibilities for lactobacilli‐mediated inhibition of H. pylori. Materials and methods: Binding and proliferation of four H. pylori and four Lactobacillus strains, simultaneously isolated after residing in the stomachs of four patients for >4 years, to human gastric mucins were investigated using microtiter‐based methods. Results: The H. pylori strains co‐isolated with lactobacilli exhibited the same mucin binding properties as demonstrated for H. pylori strains previously. In contrast, no binding to mucins was detected with the Lactobacillus strains. Proliferation of mucin‐binding H. pylori strains was stimulated by the presence of mucins, whereas proliferation of non‐binding H. pylori and Lactobacillus strains was unaffected. Associative cultures of co‐isolated H. pylori and Lactobacillus strains showed no inhibition of H. pylori proliferation because of the presence of whole bacteria or supernatant of lactobacilli. Conclusions: The presence of lactobacilli in the stomach did not select for different mucin binding properties of H. pylori, and Lactobacillus sp. did neither compete for binding sites nor inhibit the growth of co‐isolated H. pylori. The effects of human gastric mucins on H. pylori proliferation vary between strains, and the host–bacteria interaction in the mucus niche thus depends on both the H. pylori strain and the microenvironment provided by the host mucins.     

Plasmid profiles of bacteriocin-producingLactobacillus isolates from African fermented foods

Fourteen of 200Lactobacillus isolates from African fermented foods,viz. ‘wara’, ‘kenkey’, ‘ugba’, ‘ogi’, ‘kunuzarki’, ‘fufu’ and ‘iru’ were found to produce bacteriocins againstL. plantarum and only three bacteriocinogenic isolates inhibited some of the food pathogens. Plasmid analysis of the 14 bacteriocin-producing lactobacilli showed that only 5 isolates harbored plasmids ranging in size from 3.1 to 55.5 kb.     

Ability of <Emphasis Type="Italic">Lactobacillus</Emphasis> to inhibit enteric pathogenic bacteria adhesion on Caco-2 cells

The antagonistic effects of Lactobacillus against pathogenic bacteria were evaluated in vitro on cultured Caco-2 cells. Lactobacilli were added simultaneously with enteric pathogenic strains (enterotoxigenic Escherichia coli K88 or Salmonella typhimurium SARB21 and SL1344), before pathogenic strains and after pathogenic strains for competition, exclusion and displacement assays. The six lactobacilli significantly limited the adhesion and invasion of the pathogenic bacteria. In the simulating competition and exclusion assays, the adhesion of pathogenic strains was reduced by Lactobacillus strains significantly, whereas the inhibiting effect on pathogenic strains adhesion was a little weaker in the displacement assay. Furthermore, we found that the antagonistic effects of lactobacilli against K88, SARB21, and SL1344 were various. Strain R4 showed a strong inhibitory effect on the adhesion of K88 to Caco-2 cells. In the competition assay of R4, the number of viable cell-associated K88 (3.84 ± 0.10 log CFU/well) was much lower than the control group without Lactobacillus (5.98 ± 0.02 log CFU/well). Compared to the control group (6.07 ± 0.02 log CFU/well), the six Lactobacillus strains all performed strong antagonistic effects against SL1344, particularly D17 showed a higher inhibitory effect in the displacement assays (4.15 ± 0.04 log CFU/well). These results implied that several Lactobacillus strains might be useful for protecting against enteric pathogenic infection.