Impact of Periodic Presumptive Treatment for Bacterial Vaginosis on the Vaginal Microbiome among Women Participating in the Preventing Vaginal Infections Trial.

Background: Evidence suggests that specific vaginal bacteria associated with bacterial vaginosis (BV) may increase the risk of adverse health outcomes in women. Among women participating in a randomized, double-blinded trial, we assessed the effect of periodic presumptive treatment (PPT) on detection of select vaginal bacteria. Methods: High-risk women from the United States and Kenya with a recent vaginal infection received intravaginal metronidazole 750 mg plus miconazole 200 mg or placebo for 5 consecutive nights each month for 12 months. Vaginal fluid specimens were collected via polyester/polyethylene terephthalate swabs every other month and tested for bacteria, using quantitative polymerase chain reaction (PCR) assays targeting the 16S ribosomal RNA gene. The effect of PPT on bacterium detection was assessed among all participants and stratified by country. Results: Of 234 women enrolled, 221 had specimens available for analysis. The proportion of follow-up visits with detectable quantities was lower in the PPT arm versus the placebo arm for the following bacteria: BVAB1, BVAB2, Atopobium vaginae, Leptotrichia/Sneathia, and Megasphaera. The magnitude of reductions was greater among Kenyan participants as compared to US participants. Conclusions: Use of monthly PPT for 1 year reduced colonization with several bacteria strongly associated with BV. The role of PPT to improve vaginal health should be considered, and efforts to improve the impact of PPT regimens are warranted.

Effects of a combination of hinokitiol (ß-thujaplicin) and an organic acid mixture on ruminal fermentation in heifers fed a high-grain diet.

This study evaluated the effects of hinokitiol (a natural antibacterial compound extracted from Thujopsis dolabrata var. hondai) and an organic acid mixture (citrate content 50%) on ruminal fermentation. Antibacterial properties were examined by measuring minimal inhibitory concentration. Hinokitiol at 1.56µg/mL or an organic acid mixture at 1600µg/mL inhibited Streptococcus bovis growth. The combination of 0.78µg/mL hinokitiol and 200µg/mL of an organic acid mixture also inhibited S. bovis growth. Both hinokitiol and the hinokitiol and an organic acid mixture combination showed strong antibacterial properties on Gram-positive bacteria such as S. bovis, but relatively weak antibacterial activities on Gram-negative bacteria such as Megasphaera elsdenii. Three ruminally cannulated heifers were fed a bloat-producing diet containing barley, pelleted alfalfa meal, soybean meal and salt without long-cut roughage to investigate the ruminal characteristics in vivo. Feeding to heifers a bloat-producing diet containing 7.8mg/kg hinokitiol and 0.2% of an organic acid mixture significantly decreased the increase in stable ingesta volume. Hinokitiol or an organic acid mixture did not affect ruminal volatile fatty acids, protozoa and bacteria. These results suggest that a combination of hinokitiol and an organic acid mixture might reduce frothy bloat in cattle fed high-grain diets.

Persistence of antibiotic resistance: evaluation of a probiotic approach using antibiotic-sensitive Megasphaera elsdenii strains to prevent colonization of swine by antibiotic-resistant strains.

Megasphaera elsdenii is a lactate-fermenting, obligately anaerobic bacterium commonly present in the gastrointestinal tracts of mammals, including humans. Swine M. elsdenii strains were previously shown to have high levels of tetracycline resistance (MIC=64 to >256 µg/ml) and to carry mosaic (recombinant) tetracycline resistance genes. Baby pigs inherit intestinal microbiota from the mother sow. In these investigations we addressed two questions. When do M. elsdenii strains from the sow colonize baby pigs? Can five antibiotic-sensitive M. elsdenii strains administered intragastrically to newborn pigs affect natural colonization of the piglets by antibiotic-resistant (AR) M. elsdenii strains from the mother? M. elsdenii natural colonization of newborn pigs was undetectable (<10(4) CFU/g [wet weight] of feces) prior to weaning (20 days after birth). After weaning, all pigs became colonized (4 × 10(5) to 2 × 10(8) CFU/g feces). In a separate study, 61% (76/125) of M. elsdenii isolates from a gravid sow never exposed to antibiotics were resistant to chlortetracycline, ampicillin, or tylosin. The inoculation of the sow's offspring with mixtures of M. elsdenii antibiotic-sensitive strains prevented colonization of the offspring by maternal AR strains until at least 11 days postweaning. At 25 and 53 days postweaning, however, AR strains predominated. Antibiotic susceptibility phenotypes and single nucleotide polymorphism (SNP)-based identities of M. elsdenii isolated from sow and offspring were unexpectedly diverse. These results suggest that dosing newborn piglets with M. elsdenii antibiotic-sensitive strains delays but does not prevent colonization by maternal resistant strains. M. elsdenii subspecies diversity offers an explanation for the persistence of resistant strains in the absence of antibiotic selection.

Influence of dipeptidyl peptidase inhibitors on growth, peptidase activity, and ammonia production by ruminal microorganisms.

The aim was to investigate known and potential new inhibitiors of dipeptidyl peptidases (DPP) for their effects on ruminal microorganisms. Gly-Phe diazomethylketone (GPD), Ala-Ala chloromethylketone (AAC), benserazide (DL-serine 2-(2,3,4- trihydroxybenzyl) hydrazide), and diprotin A (Ile-Pro-Ile) inhibited DPP activities of Prevotella albensis, P. ruminicola, P. bryantii, P. brevis, and mixed ruminal microorganisms, though incompletely and, except for diprotin A, without absolute specificity for any of the peptidases. Leucine aminopeptidase activity of Streptococcus bovis was also inhibited by GPD and benserazide. The inhibitors had no effect on the growth of the bacteria, except for GPD, which inhibited growth of P. albensis when only peptides were available for growth. Benserazide had some inhibitory effects on the growth of Megasphaera elsdenii and Prevotella spp., even in the absence of peptides. The predatory activity of ciliate protozoa on bacteria was unaffected by DPP inhibitors. Ammonia production from casein by mixed ruminal microorganisms was inhibited significantly (P < 0.05) by AAC (29% inhibition) and benserazide (33%). It was concluded that DPP inhibitors can influence the rate of NH3 production in the rumen and may form the basis for developing protein-sparing feed additives for ruminants.