Species-specific oligonucleotide probes for the detection and identification of Lactobacillus isolated from mouse faeces

AIMS: To develop species-specific monitoring techniques for rapid detection and identification of Lactobacillus isolated from mouse faeces. METHODS AND RESULTS: The specificity of oligonucleotide probes was evaluated by dot blot hybridization to 16S rDNA and 23S rDNA amplified by PCR from 12 Lactobacillus type strains and 100 strains of Lactobacillus isolated from mouse faeces. Oligonucleotide probes specific for each Lactobacillus species hybridized only with targeted rDNA. The Lactobacillus strains isolated from mouse faeces were identified mainly as Lactobacillus intestinalis, L. johnsonii, L. murinus and L. reuteri using species-specific probes. 16S rDNA of eight unidentified isolates were sequenced and two new probes were designed. Four of eight strains of unhybridized Lactobacillus were identified as L. johnsonii/gasseri group, and the remaining four strains as L. vaginalis. CONCLUSIONS: The species-specific probe set of L. intestinalis, L. johnsonii, L. murinus, L. reuteri and L. vaginalis in this study was efficient for rapid identification of Lactobacillus isolated from mouse faeces. SIGNIFICANCE AND IMPACT OF THE STUDY: The oligonucleotide probe set for Lactobacillus species harboured in the mouse intestine, can be used for rapid identification of lactobacilli and monitoring of the faecal Lactobacillus community.     

Genomic diversity of cultivable Lactobacillus populations residing in the neonatal and adult gastrointestinal tract

The objective of this study was to investigate the cultivable Lactobacillus population in adult and infant faecal material to identify strains shared across a number of individuals. A range of lactobacilli isolated on Lactobacillus-selective agar from faeces of 16 infants and 11 adults were genetically fingerprinted and further characterized by 16S rRNA gene sequencing. The relatedness of all the Lactobacillus strains isolated to known species was also determined both genetically and phenotypically. This study revealed that the human intestine is initially colonized by only a few (1-2) different cultivable strains whereas in adults the pattern becomes more complex with a higher diversity of strains. The adult samples contained three genetically distinct Lactobacillus strains in some cases, while infant samples generally harboured only one dominant Lactobacillus strain. Moreover, the species in general appeared to differ with Lactobacillus rhamnosus and Lactobacillus casei/paracasei found mainly in adults, whereas Lactobacillus gasseri and Lactobacillus salivarius were more commonly isolated in infant samples. The data reaffirm the differences in Lactobacillus populations both between individual subjects and between the infant and adult, with an overall change in the diversity and complexity from early stages of life to adulthood.     

Monitoring and survival of Lactobacillus gasseri SBT2055 in the human intestinal tract

The monitoring and survival of Lactobacillus gasseri SBT2055 in the human intestinal tract was investigated with seven healthy subjects having a low number of fecal lactobacilli. An increase of fecal lactobacilli (10(3.2-5.2) CFU/g feces) was recognized after ingestion of yogurt with SBT2055 by the subjects. A high positive rate of L. gasseri in fecal lactobacilli detected from the subjects (over 70% at 2nd weeks of feeding) was also observed during the ingestion period using the species-specific PCR system. These findings indicate that the SBT2055 strain in yogurt survived in the human intestinal tract and was recovered from human feces.     

Comparison of agar plate and real-time PCR on enumeration of Lactobacillus, Clostridium perfringens and total anaerobic bacteria in dog faeces

AIMS: To compare agar plate and real-time PCR methods on enumeration of total anaerobic bacteria, Lactobacillus and Clostridium perfringens in dog faeces. METHODS AND RESULTS: Thirty-two faecal specimens from Labrador retriever dogs were used to compare agar plate and real-time PCR enumeration methods for Lactobacillus, C. perfringens and total anaerobic bacteria. Total anaerobic bacteria, C. perfringens and Lactobacillus of faeces were counted (as CFU g(-1) faeces) for 48-h incubation at 37 degrees C in an anaerobic gas chamber on genus-selective media. Total genomic DNA from samples was extracted by the QIAamp DNA stool mini kit. The quantification of DNA (as DNA copy per gram faeces) by real-time PCR was performed with a LightCycler system with the QuantiTect SYBR green PCR kit for PCR amplification. The results indicated that there was a significant correlation between CFU and DNA copy of Lactobacillus (R2 = 0.78, P < 0.01) and total anaerobic bacteria (R2 = 0.21, P < 0.05); but no correlation was found between CFU and DNA copy of C. perfringens. The regression equations for Lactobacillus and total anaerobic bacteria were log(DNA copy) = 0.83 x log(CFU) + 1.43 and log(DNA copy) = 1.62 x log(CFU) - 6.32 respectively. CONCLUSIONS: The real-time PCR method could be used to enumerate Lactobacillus within 2 days when compared with plating method which requires 5-6 days. SIGNIFICANCE AND IMPACT OF THE STUDY: The real-time PCR method and the primer set for Lactobacillus spp. harboured in the dog intestine can be used for rapid enumeration of lactobacilli and monitoring of the faecal Lactobacillus community.     

Dominant cultivable Lactobacillus species from the feces of healthy adults in northern Spain.

The aim of this study was to identify numerically dominant cultivable lactobacilli species in the feces of healthy adults. Ten individuals from Asturias, northern Spain, were chosen. Bacterial colonies grown under anoxic conditions on MRS with cysteine were microscopically examined for lactobacilli. Isolates were subsequently grouped based on the analysis of their carbohydrate fermentation profiles and then identified by partial amplification, sequencing, and comparison of their 16S rRNA gene sequences. Lactobacilli varied from undetectable levels in three subjects (10(5) CFU/g feces) to around 10(9) CFU/g feces. Among the 71 isolates obtained from seven individuals, 12 Lactobacillus species were identified. High interindividual variation was observed in terms of total numbers, number of species, and dominant species. Lactobacillus paracasei was found in four of the seven individuals; L. gasseri, L. delbrueckii, and L. plantarum in three. Phenotyping showed that only one strain per species was in the majority in each individual.     

Characterization of dominant cultivable lactobacilli and their antibiotic resistance profiles from faecal samples of weaning piglets

AIMS: To examine the lactic acid bacteria flora of weaning piglets, to define the distribution of different lactobacilli species in piglet faecal samples, and to determine the susceptibility phenotype to 11 antibiotic of different families. METHODS AND RESULTS: The faecal samples were taken from piglets with good herd status at 11 and 28 days after weaning. The Lactobacillus isolates (n = 129) from 78 animals housed in pairs in 39 pens were preliminarily identified by their morphology and biochemical characteristics. Partial 16S ribosomal DNA (16S rDNA) was used to identify the isolates to the species level, and RAPD (randomly amplified polymorphism DNA) profiles to differentiate Lactobacillus isolates to the strain level. Based on these studies, 67 strains were selected for antibiotic resistant tests. The most numerous Lactobacillus species found in the piglets was Lactobacillus reuteri (n = 43). Other lactobacilli were L. salivarius (n = 15), L. agilis (n = 4), L. johnsonii (n = 2), L. vaginalis (n = 1), L. mucosae (n = 1) and L. gallinarum (n = 1). All the strains were susceptible to chloramphenicol, ampicillin and gentamicin. Two L. salivarius isolates and two L. reuteri isolates were found to be multiresistant. CONCLUSIONS: This study indicates that the faecal Lactobacillus flora in piglets consists mainly of L. reuteri, L. salivarius and L. acidophilus group lactobacilli, and the distribution of lactobacilli is similar between individuals of the same age and with the same diet. Most of the Lactobacillus isolates tested were sensitive to the antibiotics used in this study. SIGNIFICANCE AND IMPACT OF THE STUDY: Valuable information on Lactobacillus species distribution and their antibiotic resistance profiles in piglets is obtained.     

Comparison of two selective media for the detection and enumeration of Lactobacilli in human faeces

The enumeration of faecal bacteria is an important requirement for many studies of bowel health. One approach is the use of selective culture media for the culture and identification of genera or species from faeces. This study compares the culture of Lactobacilli from dilution series of faecal samples from six healthy human volunteers on two commonly used media, LAMVAB and Rogosa agar. Colonies were counted after a 72-h anaerobic incubation at 37 degrees C, and colony morphology recorded by a single observer. DNA was isolated from a representative number of colonies and genus-specific PCR, single-stranded conformation polymorphism (SSCP) and DNA sequencing performed. Total colony counts ranged from <3.00 to 7.48 log(10) cfu/g of faeces for LAMVAB and 5.09 to 7.66 log(10) cfu/g for Rogosa. For each subject, the total colony count was higher on Rogosa than that obtained with LAMVAB agar. SSCP analysis and DNA sequencing indicated that colony morphology was not an accurate predictor of genus identity. Growth of two species, Lactobacillus acidophilus and Lactobacillus gasseri, was not supported on LAMVAB medium. Rogosa agar was more likely to support growth of non-Lactobacillus species. Therefore, neither medium gave a fully accurate representation of the Lactobacilli species present in human faecal samples.     

Genetic diversity of vaginal lactobacilli from women in different countries based on 16S rRNA gene sequences

AIMS: Lactobacilli are widely distributed in food and the environment, and some colonize the human body as commensal bacteria. The aim of this study was to determine the species of lactobacilli that colonize the vagina and compare them with those found in food and the environment. METHODS AND RESULTS: Thirty-five Lactobacillus strains from women from seven countries were isolated, and sequences from 16S rRNA genes were determined and compared with existing data in GenBank. A phylogenetic tree was achieved using the Neighbour-Joining method based on the analysis of 1465 nucleotides. The results showed that most vaginal isolates were L. crispatus, L. jensenii and L. gasseri. Some were L. vaginalis, L. fermentum, L. mucosae, L. paracasei and L. rhamnosus. Two isolates from a native American woman displayed distinct branches, indicating novel phylotypes. Few vaginal isolates matched food or environmental Lactobacillus species. CONCLUSIONS: Most women worldwide were colonized by three common Lactobacillus species: L. crispatus, L. jensenii and L. gasseri. SIGNIFICANCE AND IMPACT OF THE STUDY: Knowledge of vaginal Lactobacillus species richness and distribution in women worldwide may lead to the design of better probiotic products as bacterial replacement therapy.     

Characterization and selection of vaginal Lactobacillus strains for the preparation of vaginal tablets

AIMS: To characterize and select Lactobacillus strains for properties that would make them a good alternative to the use of antibiotics to treat human vaginal infections. METHODS AND RESULTS: Ten Lactobacillus strains belonging to four different Lactobacillus species were analysed for properties relating to mucosal colonization or microbial antagonism (adhesion to human epithelial cells, hydrogen peroxide production, antimicrobial activity towards Gardnerella vaginalis and Candida albicans and coaggregation with pathogens). The involvement of electrostatic interactions and the influence of bacterial metabolic state in the binding of lactobacilli to the cell surface were also studied. Adherence to epithelial cells varied greatly among the Lactobacillus species and among different strains belonging to the same Lactobacillus species. The reduction in surface negative electric charge promoted the binding of several Lactobacillus strains to the cell membrane whereas lyophilization reduced the adhesion capacity of many isolates. The antimicrobial activity of lactobacilli culture supernatant fluids was not directly related to the production of H2O2. CONCLUSIONS: Three strains (Lactobacillus brevis CD2, Lact. salivarius FV2 and Lact. gasseri MB335) showed optimal properties and were, therefore, selected for the preparation of vaginal tablets. The selected strains adhered to epithelial cells displacing vaginal pathogens; they produced high levels of H2O2, coaggregated with pathogens and inhibited the growth of G. vaginalis. SIGNIFICANCE AND IMPACT OF THE STUDY: The dosage formulation developed in this study appears to be a good candidate for the probiotic prophylaxis and treatment of human vaginal infections.     

Presence of drug resistance in intestinal lactobacilli of dairy and human origin in Turkey

The prevalence of different resistance genes was investigated in lactobacilli of human and dairy origin by PCR. The presence of erm, van, tet, and cat-TC genes were determined in 16 raw milk, 15 cream, 10 yogurt, 50 hand-made cheese, and 20 industrially produced white-cheese samples of dairy origin and 16 mouth, 32 fecal, and 36 vaginal samples from different subjects of human origin. Lactobacilli of dairy and human origin were found to carry only erm(B) and tet(M) genes. The majority of the isolates, Lactobacillus crispatus (61), Lactobacillus gasseri (49), Lactobacillus plantarum (80) studied were found to harbor either erm(B) or tet(M) gene or both. No resistant lactobacilli was found in raw-milk and cream samples. All the human fecal samples and the majority of vaginal (29 of 36) and mouth (10 of 14) samples were found to carry the resistance genes. While a third of the hand-made cheeses carried resistant lactobacilli only one industrially produced cheese was found to carry resistant lactobacilli. Furthermore, the genes were found in the non-starter species, Lactobacillus acidophilus and Lb. plantarum, indicating that industrially produced cheeses in this respect could be considered more favorable. These results indicate that drug resistance seems to be very common in Turkey. Even though the number of dairy samples harboring the resistance genes (17 of 111) is smaller in regards to human samples, 10% of them were still found to carry the resistance genes as well. The presence of the resistance genes in majority of the samples of human origin and in minority of the samples of dairy origin indicates that drug resistance may be acquired in the intestinal tract during passage and spread to dairy products by the hands of workers during production.     

Distribution of salivary Lactobacillus and Bifidobacterium species in periodontal health and disease

We surveyed the distribution of salivary Lactobacillus and Bifidobacterium species in periodontitis patients and healthy subjects. Approximately 700 lactobacilli and 300 bifidobacterial isolates were obtained from 16 young, orally healthy subjects (mean age +/- standard deviation: 21.0+/-2.0 y), 16 periodontitis patients (51.6+/-13.8 y), and 14 well-maintained former periodontitis patients (60.2+/-9.6 y). Among eleven Lactobacillus species detected in saliva, L. salivarius, L. gasseri, and L. fermentum were prevalent, but no species was specifically associated with periodontal health. In contrast, of four Bifidobacterium species, B. adolescentis was specifically (P<0.05) prevalent in young healthy subjects compared with the other two groups. Furthermore, the bifidobacterial count of the well-maintained subjects was the highest (P<0.05) among the groups. These results suggest that bifidobacterial count and species might be associated with periodontal health status and/or age.     

Exploring bacterial flora in oral squamous cell carcinoma: a microbiological study

The oral cavity contains a unique and diverse micro?ora. While most of these organisms exhibit commensalism, shifts in bacterial community dynamics cause pathological changes within the oral cavity and at distant sites. We assessed the microbial flora using cultured saliva and oral swabs from subjects with oral squamous cell carcinoma (OSCC) and healthy controls. Microbial samples were collected from the carcinoma site, contralateral healthy mucosa, and saliva of the study group and samples were collected from healthy mucosa and saliva of controls. Samples were stored on ice and transported to the laboratory for culture. The median number of colony forming units (CFU)/ml at carcinoma sites was significantly greater than at the contralateral healthy mucosa. Similarly,?in saliva of carcinoma subjects, the median number of CFU/ml was significantly greater than in saliva of control subjects.     

Transferability of a tetracycline resistance gene from probiotic <Emphasis Type="Italic">Lactobacillus reuteri</Emphasis> to bacteria in the gastrointestinal tract of humans

The potential of Lactobacillus reuteri as a donor of antibiotic resistance genes in the human gut was investigated by studying the transferability of the tetracycline resistance gene tet(W) to faecal enterococci, bifidobacteria and lactobacilli. In a double-blind clinical study, seven subjects consumed L. reuteri ATCC 55730 harbouring a plasmid-encoded tet(W) gene (tet(W)-reuteri) and an equal number of subjects consumed L. reuteri DSM 17938 derived from the ATCC 55730 strain by the removal of two plasmids, one of which contained the tet(W) gene. Faecal samples were collected before, during and after ingestion of 5 × 10⁸ CFU of L. reuteri per day for 14 days. Both L. reuteri strains were detectable at similar levels in faeces after 14 days of intake but neither was detected after a two-week wash-out period. After enrichment and isolation of tetracycline resistant enterococci, bifidobacteria and lactobacilli from each faecal sample, DNA was extracted and analysed for presence of tet(W)-reuteri using a real-time PCR allelic discrimination method developed in this study. No tet(W)-reuteri signal was produced from any of the DNA samples and thus gene transfer to enterococci, bifidobacteria and lactobacilli during intestinal passage of the probiotic strain was non-detectable under the conditions tested, although transfer at low frequencies or to the remaining faecal bacterial population cannot be excluded.     

16S ribosomal DNA analysis of the faecal lactobacilli composition of human subjects consuming a probiotic strain Lactobacillus acidophilus NCFM

AIMS: The aims of this study were to evaluate the ability of exogenous Lactobacillus acidophilus strain NCFM to survive through the human gastro-intestinal (GI) tract, and to evaluate the selectivity of Rogosa SL medium for faecal lactobacilli. METHODS AND RESULTS: The composition of the faecal lactobacilli of 10 healthy subjects was monitored for two weeks prior to, two weeks during and two weeks after the administration of the Lact. acidophilus strain NCFM consumed with skim milk (daily dose 10(10) viable cells). Fresh faecal samples were collected, processed and cultured on Rogosa SL selective medium for lactobacilli enumeration. Colonies demonstrating various morphologies were identified and purified for 16S ribosomal DNA sequence analysis for speciation of colonial genotype. The species composition of cultivable faecal lactobacilli changed considerably during consumption of the strain NCFM. CONCLUSIONS: The probiotic Lact. acidophilus strain NCFM can survive through the human GI tract, but cannot colonize itself during the two-week consumption. Rogosa SL medium is selective for faecal lactobacilli. However, genetic analysis is required for colony speciation. SIGNIFICANCE AND IMPACT OF THE STUDY: It is demonstrated that continuous consumption is necessary to maintain a high population of the probiotic strain, and that the Rogosa SL medium is reliable.     

Lactobacillus strains isolated from the vaginal microbiota of healthy women inhibit Prevotella bivia and Gardnerella vaginalis in coculture and cell culture

The purpose of this study was to investigate how human vaginal isolates of Lactobacillus acidophilus, Lactobacillus jensenii, Lactobacillus gasseri and Lactobacillus crispatus inhibit the vaginosis-associated pathogens Gardnerella vaginalis and Prevotella bivia. Results show that all the strains in coculture condition reduced the viability of G. vaginalis and P. bivia, but with differing degrees of efficacy. The treatment of G. vaginalis- and P. bivia-infected cultured human cervix epithelial HeLa cells with L. gasseri strain KS120.1 culture or cell-free culture supernatant (CFCS) results in the killing of the pathogens that are adhering to the cells. The mechanism of the killing activity is not attributable to low pH and the presence of lactic acid alone, but rather to the presence of hydrogen peroxide and proteolytic enzyme-resistant compound(s) present in the CFCSs. In addition, coculture of G. vaginalis or P. bivia with L. gasseri KS120.1 culture or KS120.1 bacteria results in inhibition of the adhesion of the pathogens onto HeLa cells.     

Survivability of a probiotic Lactobacillus casei in the gastrointestinal tract of healthy human volunteers and its impact on the faecal microflora

AIM: The aim of this study was to measure the gastrointestinal survival of Lactobacillus casei and its impact on the gut microflora in healthy human volunteers. METHODS AND RESULTS: Twenty healthy volunteers took part in a double-blind placebo-controlled probiotic feeding study (10 fed probiotic, 10 fed placebo). The probiotic was delivered in two 65 ml aliquots of fermented milk drink (FMD) daily for 21 days at a dose of 8.6 +/- 0.1 Log(10)Lact. casei CFU ml(-1) FMD. Faecal samples were collected before, during and after FMD or placebo consumption, and important groups of faecal bacteria enumerated by fluorescent in situ hybridization (FISH) using oligonucleotide probes targeting the 16S rRNA. The fed Lact. casei was enumerated using selective nutrient agar and colony identity confirmed by pulsed field gel electrophoresis. Seven days after ingestion of FMD, the Lact. casei was recovered from faecal samples taken from the active treatment group at 7.1 +/- 0.4 Log(10) CFU g(-1) faeces (mean +/- SD, n = 9) and numbers were maintained at this level until day 21. Lact. casei persisted in six volunteers until day 28 at 5.0 +/- 0.9 Log(10) CFU g(-1) faeces (mean +/- SD, n = 6). Numbers of faecal lactobacilli increased significantly upon FMD ingestion. In addition, the numbers of bifidobacteria were higher on days 7 and 21 than on days 0 and 28 in both FMD fed and placebo fed groups. Consumption of Lact. casei had little discernible effect on other bacterial groups enumerated. CONCLUSIONS: Daily consumption of FMD enabled a probiotic Lact. casei strain to be maintained in the gastrointestinal tract of volunteers at a stable relatively high population level during the probiotic feeding period. SIGNIFICANCE AND IMPACT OF THE STUDY: The study has confirmed that this probiotic version of Lact. casei survives well within the human gastrointestinal tract.     

Rapid identification of 11 human intestinal Lactobacillus species by multiplex PCR assays using group- and species-specific primers derived from the 16S-23S rRNA intergenic spacer region and its flanking 23S rRNA

Rapid and reliable two-step multiplex polymerase chain reaction (PCR) assays were established to identify human intestinal lactobacilli; a multiplex PCR was used for grouping of lactobacilli with a mixture of group-specific primers followed by four multiplex PCR assays with four sorts of species-specific primer mixtures for identification at the species level. Primers used were designed from nucleotide sequences of the 16S-23S rRNA intergenic spacer region and its flanking 23S rRNA gene of members of the genus Lactobacillus which are commonly isolated from human stool specimens: Lactobacillus acidophilus, Lactobacillus crispatus, Lactobacillus delbrueckii (ssp. bulgaricus and ssp. lactis), Lactobacillus fermentum, Lactobacillus gasseri, Lactobacillus jensenii, Lactobacillus paracasei (ssp. paracasei and ssp. tolerans), Lactobacillus plantarum, Lactobacillus reuteri, Lactobacillus rhamnosus and Lactobacillus salivarius (ssp. salicinius and ssp. salivarius). The established two-step multiplex PCR assays were applied to the identification of 84 Lactobacillus strains isolated from human stool specimens and the PCR results were consistent with the results from the DNA-DNA hybridization assay. These results suggest that the multiplex PCR system established in this study is a simple, rapid and reliable method for the identification of common Lactobacillus isolates from human stool samples.     

Quantitative evaluation of adhesion of lactobacilli isolated from human intestinal tissues to human colonic mucin using surface plasmon resonance (BIACORE assay)

AIMS: To isolate lactobacilli from the mucus layer of the human intestine and evaluate their adhesion abilities using a BIACORE assay. METHODS AND RESULTS: Thirty strains of lactobacilli were isolated from the mucus layer of normal human intestinal tissues using conventional plate culture. The strains were identified using homology comparisons of the 16S rDNA sequence to databases as Lactobacillus salivarius (26%), Lactobacillus fermentum (13%), Lactobacillus gasseri (10%), Lactobacillus paracasei (7%), Lactobacillus casei (3%), Lactobacillus mucosae (3%) and Lactobacillus plantarum (3%). Lactobacillus plantarum LA 318 shows the highest adhesion to human colonic mucin (HCM) using the BIACORE assay at 115.30 +/- 12.37 resonance unit (RU). The adhesion of cell wall surface proteins from strain LA 318 was significantly higher to HCM than to bovine serum albumin (BSA; P < 0.05). CONCLUSIONS: We isolated 30 strains of lactobacilli. Lactobacillus salivarius was the predominant species of lactobacilli isolated in this study. The adhesion of strain LA 318 isolated from human transverse colon to its mucin was shown. The adhesion could be mediated by lectin-like components on the bacterial cell surface. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study where lactobacilli were isolated from human intestinal tissues and shown to adhere to HCM.     

Adherence of clinically isolated lactobacilli to human cervical cells in competition with Neisseria gonorrhoeae

Lactobacilli are normal inhabitants of our microbiota and are known to protect against pathogens. Neisseria gonorrhoeae is a human specific pathogenic bacterium that colonises the urogenital tract where it causes gonorrhoea. In this study we analysed early interactions between lactobacilli and gonococci and investigated how they compete for adherence to human epithelial cervical cells. We show that lactobacilli adhere at various levels and that the number of adherent bacteria does not correlate to the level of protection against gonococcal infection. Protection against gonococcal adhesion varied between Lactobacillus species. Lactobacillus crispatus, Lactobacillus gasseri and Lactobacillus reuteri were capable of reducing gonococcal adherence while Lactobacillus rhamnosus was not. Lactobacillus strains of vaginal origin had the best capacity to remain attached to the host cell during gonococcal adherence. Further, we show that gonococci and lactobacilli interact with each other with resultant lactobacilli incorporation into the gonococcal microcolony. Hence, gonococci bind to colonised lactobacilli and this complex frequently detaches from the epithelial cell surface, resulting in reduced bacterial colonisation. Also, purified gonococcal pili are capable of removing adherent lactobacilli from the cell surface. Taken together, we reveal novel data regarding gonococcal and lactobacilli competition for adherence that will benefit future gonococcal prevention and treatments.     

Diversity of the Lactobacillus group in breast milk and vagina of healthy women and potential role in the colonization of the infant gut

AIMS: To evaluate the diversity of the Lactobacillus group in breast milk and the vagina of healthy women and understand their potential role in the infant gut colonization using the 16S rRNA gene approaches. METHODS AND RESULTS: Samples of breast milk, vaginal swabs and infant faeces were aseptically collected from five mothers whose neonates were born by vaginal delivery and another five that had their babies by caesarean section. After polymerase chain reaction (PCR) amplification using Lactobacillus group-specific primers, amplicons were analysed by denaturing gradient gel electrophoresis (DGGE). Clone libraries were constructed to describe the Lactobacillus group diversity. DGGE fingerprints were not related to the delivery method. None of the species detected in vaginal samples were found in breast milk-derived libraries and only few were detected in infant faeces. CONCLUSIONS: The bacterial composition of breast milk and infant faeces is not related to the delivery method. SIGNIFICANCE AND IMPACT OF THE STUDY: It has been suggested that neonates acquire lactobacilli by oral contamination with vaginal strains during delivery; subsequently, newborns would transmit such bacteria to the breast during breastfeeding. However, our findings confirm, at the molecular level that in contrast to the maternal vagina, breast milk seems to constitute a good source of lactobacilli to the infant gut.