The vaginal bacterial microbiota of 19 premenopausal women was examined by PCR-denaturing gradient gel electrophoresis (DGGE) and sequencing of the V2-V3 region of the 16S rRNA gene. Ten of the women were studied further to investigate the effect and persistence of vaginally inserted capsules containing viable lactobacilli. PCR-DGGE indicated that most subjects had a microbiota represented by one to three dominant DNA fragments. Analysis of these fragments revealed that 79% of the women possessed sequences with high levels of similarity to Lactobacillus species sequences. Sequences homologous to Lactobacillus iners sequences were the most common and were detected in 42% of the women tested. Alteration of the vaginal microbiota could be detected by PCR-DGGE in several women after the instillation of lactobacilli. Additionally, randomly amplified polymorphic DNA analysis of lactobacilli isolated from selective media demonstrated that the exogenous strains could be detected for up to 21 days in some subjects. This study demonstrates that non-culture-based techniques, such as PCR-DGGE, are useful adjuncts for studies of the vaginal microbiota.The microbes that inhabit the vagina play a major role in illnesses of the host, including bacterial vaginosis, yeast vaginitis, cancer, and sexually transmitted diseases, such as human immunodeficiency virus infection, as well as in the maintenance of a healthy tract. Our understanding of the nature and functionality of these organisms has progressed in recent years, but it is still far from optimal. For some time the microbiota of so-called normal women of child-bearing age was believed to be dominated by Lactobacillus acidophilus and Lactobacillus fermentum, followed by Lactobacillus brevis, Lactobacillus jensenii, Lactobacillus casei, and other species (12). More recently, molecular methods have shown that Lactobacillus crispatus and Lactobacillus jensenii are the most common isolates (2, 12), and in one study a previously undescribed Lactobacillus species was found in 15% of women (2). The development of denaturing gradient gel electrophoresis (DGGE) has provided an exciting tool to analyze a given population of organisms within a host. To date, this method has been used successfully to examine the intestinal microbiotas of adults and children (5, 18).Continuous application of certain Lactobacillus strains vaginally and orally has been shown to alter the microbiota from a microbiota indicative of bacterial vaginosis to a microbiota that is dominated by lactobacilli and regarded as normal (10). Instillation of probiotic lactobacilli has the potential to make a significant impact on the health of women, and therefore, it is important to understand how the vaginal microbiota changes and adapts to the presence of these strains. Therefore, the first goal of the present study was to utilize PCR-DGGE and to sequence different 16S DNA fragments to determine which bacterial species were most common among the vaginal samples of premenopausal women. The second goal was to use DGGE to...

Staphylococcus aureus is a common cause of community and hospital-acquired infections. Moreover, the clinical impact of S. aureus is on the rise because of the global increase in the incidence of multidrug-resistant strains and its growing prevalence as a major cause of surgical infections. As a result, there is a pressing need to identify new antistaphylococcal agents and preventative strategies that will help in the management of these types of infections. This report describes the successful use of a probiotic, Lactobacillus fermentum RC-14, and its secreted biosurfactant to inhibit surgical implant infections caused by S. aureus. L. fermentum RC-14 and its secreted biosurfactant both significantly inhibited S. aureus infection and bacteria adherence to surgical implants.

Persister cells represent a multidrug-tolerant (MDT), physiologically distinct subpopulation of bacteria. The ability of these organisms to survive lethal antibiotic doses raises concern over their potential role in chronic disease, such as recurrent urinary tract infection (RUTI). Persistence is believed to be conveyed through global metabolic dormancy, which yields organisms unresponsive to external stimuli. However, recent studies have contested this stance. Here, various antibiotics that target different cellular processes were used to dissect the activity of transcription, translation, and peptidoglycan turnover in persister cells. Differential susceptibility patterns were found in type I and type II persisters, and responses differed between Staphylococcus saprophyticus and Escherichia coli uropathogens. Further, SOS-deficient strains were sensitized to ciprofloxacin, suggesting DNA gyrase activity in persisters and indicating the importance of active DNA repair systems for ciprofloxacin tolerance. These results indicate that global dormancy per se cannot sufficiently account for antibiotic tolerance. Rather, the activity of individual cellular processes dictates multidrug tolerance in an antibiotic-specific fashion. Furthermore, the susceptibility patterns of persisters depended on their mechanisms of onset, with subinhibitory antibiotic pretreatments selectively shutting down cognate targets and increasing the persister fraction against the same agent. Interestingly, antibiotics targeting transcription and translation enhanced persistence against multiple agents indirectly related to these processes. Conducting these assays with uropathogenic E. coli isolated from RUTI patients revealed an enriched persister fraction compared to organisms cleared with standard antibiotic therapy. This finding suggests that persister traits are either selected for during prolonged antibiotic treatment or initially contribute to therapy failure.

Streptococcus salivarius strains commonly produce bacteriocins as putative anti-competitor or signalling molecules. Here we report that bacteriocin production by the oral probiotic strain S. salivarius K12 is encoded by a large (ca. 190 kb) plasmid. Oral cavity transmission of the plasmid from strain K12 to a plasmid-negative variant of this bacterium was demonstrated in two subjects. Tests of additional S. salivarius strains showed large (up to ca. 220 kb) plasmids present in bacteriocin-producing isolates. Various combinations (up to 3 per plasmid) of loci encoding the known streptococcal lantibiotics salivaricin A, salivaricin B, streptin and SA-FF22 were localised to these plasmids. Since all bacteriocin-producing strains of S. salivarius tested to date appear to harbour plasmids, it appears that they may function as mobile repositories for bacteriocin loci, especially those of the lantibiotic class.