Elastase activity of anaerobes isolated from amniotic fluid with preterm premature rupture of membranes

Gardnerella vaginalis and Prevotella bivia Trigger Distinct and Overlapping Phenotypes in a Mouse Model of Bacterial Vaginosis

BACKGROUND

Bacterial vaginosis (BV) is a common imbalance of the vaginal microbiota characterized by overgrowth of diverse Actinobacteria, Firmicutes, and Gram-negative anaerobes. Women with BV are at increased risk of secondary reproductive tract infections and adverse pregnancy outcomes. However, which specific bacteria cause clinical features of BV is unclear.

METHODS

We previously demonstrated that Gardnerella vaginalis could elicit many BV features in mice. In this study, we established a BV model in which we coinfected mice with G. vaginalis and another species commonly found in women with BV: Prevotella bivia.

RESULTS

This coinfection model recapitulates several aspects of human BV, including vaginal sialidase activity (a diagnostic BV feature independently associated with adverse outcomes), epithelial exfoliation, and ascending infection. It is notable that G. vaginalis facilitated uterine infection by P. bivia.

CONCLUSIONS

Taken together, our model provides a framework for advancing our understanding of the role of individual or combinations of BV-associated bacteria in BV pathogenesis.

Persistent microbial dysbiosis in preterm premature rupture of membranes from onset until delivery

Background. Preterm Premature Rupture of Membranes (PPROM) is a major leading cause of preterm births. While the cause for PPROM remains unidentified, it is anticipated to be due to subclinical infection, since a large proportion of PPROM patients display signs of chorioamnionitis. Since subclinical infections can be facilitated by dysbiosis, our goal was to characterize the vaginal microbiome and amniotic fluid discharge upon PPROM, through latency antibiotic treatment, and until delivery, to detect the presence of pathogens, microbiota alteration, and microbial response to treatment. Methods. Enrolled subjects (15) underwent routine institutional antenatal care for PPROM, including the administration of latency antibiotics. Serial vaginal swabs were obtained from diagnosis of PPROM through delivery and the sequencing of the V3-V5 region of the 16S rRNA gene was performed for all collected samples. Results. The results show that Lactobacilli species were markedly decreased when compared to vaginal swabs collected from uncomplicated pregnancy subjects with a matched gestational time. Prevotella and Peptoniphilus were the most prevalent taxa in PPROM subjects at presentation. The vaginal microbiome of the PPROM subjects varied substantially intra- and inter-subjects. Several taxa were found to be significantly reduced during and after the antibiotic treatment: Weeksella, Lachnospira, Achromobacter, and Pediococcus. In contrast, Peptostreptococcus and Tissierellaceae ph2 displayed a significant increase after the antibiotic treatment. However, the relative abundance of Lactobacillus, Prevotella, and Peptoniphilus was not substantially impacted during the hospitalization of the PPROM subjects. The deficiency of Lactobacillus, and constancy of known pathogenic species, such as Prevotella and Peptoniphilus during and after antibiotics, highlights the persistent dysbiosis and warrants further investigation into mitigating approaches. Discussion. PPROM is responsible for one third of all preterm births. It is thought that subclinical infection is a crucial factor in the pathophysiology of PPROM because 25-40% of patients present signs of chorioamnionitis on amniocentesis. Here we sought to directly assess the bacterial content of the vagina and leaking amniotic fluid of subjects at presentation, throughout treatment and up until delivery, in order to search for common pathogens, microbiota changes, and microbial response to latency antibiotic treatment. We have found that the vaginal microbiome of PPROM subjects is highly variable and displays significant changes to treatment. However, the unchanging deficiency of Lactobacillus, and persistence of known pathogenic species, such as Prevotella and Peptoniphilus from presentation, through antibiotic treatment and up until delivery, highlights the persistent dysbiosis and warrants further investigation into mitigating approaches.

Gram-positive anaerobic cocci--commensals and opportunistic pathogens

Among the Gram-positive anaerobic bacteria associated with clinical infections, the Gram-positive anaerobic cocci (GPAC) are the most prominent and account for approximately 25-30% of all isolated anaerobic bacteria from clinical specimens. Still, routine culture and identification of these slowly growing anaerobes to the species level has been limited in the diagnostic laboratory, mainly due to the requirement of prolonged incubation times and time-consuming phenotypic identification. In addition, GPAC are mostly isolated from polymicrobial infections with known pathogens and therefore their relevance has often been overlooked. However, through improvements in diagnostic and in particular molecular techniques, the isolation and identification of individual genera and species of GPAC associated with specific infections have been enhanced. Furthermore, the taxonomy of GPAC has undergone considerable changes over the years, mainly due to the development of molecular identification methods. Existing species have been renamed and novel species have been added, resulting in changes of the nomenclature. As the abundance and significance of GPAC in clinical infections grow, knowledge of virulence factors and antibiotic resistance patterns of different species becomes more important. The present review describes recent advances of GPAC and what is known of the biology and pathogenic effects of Anaerococcus, Finegoldia, Parvimonas, Peptoniphilus and Peptostreptococcus, the most important GPAC genera isolated from human infections.

Retrospective cohort study: a comparison of two different management strategies in patients with preterm premature rupture of membranes

PURPOSE

Perinatal outcomes were compared before and after changes in the treatment policy to improve the management for preterm PROM (pPROM).

METHODS

This is a retrospective analysis of 99 cases of pPROM diagnosed between 27 and 34 weeks of gestation, which were managed according to the following two different protocols. Group A (47 cases): tocolytic therapy was continued to prevent preterm delivery until clinical chorioamnionitis (CAM) was diagnosed between January 2000 and June 2004. Group B (52 cases): labor was induced or cesarean section performed when oligohydramnios was diagnosed and/or elevation elastase (EL) of amnion was detected by amniocentesis between July 2004 and July 2009. The outcomes of the cases in each group were compared with regard to the extension of pregnancy period, reasons for delivery, perinatal complications, stage of pathological CAM and funisitis (FUN), neonatal serum IgM concentration, mortality, and morbidity.

RESULTS

The incidences of pathological CAM and FUN were significantly lower in Group B than in Group A. The concentration of neonatal serum IgM was also significantly lower in Group B than in Group A.

CONCLUSIONS

The addition of oligohydramnios and elevation EL of amnion as indicative factors of intrauterine infection might lead to a reduction in the severity of fetal infection in cases of pPROM.

Bovine milk fermented with Lactobacillus rhamnosus L8020 decreases the oral carriage of mutans streptococci and the burden of periodontal pathogens

AIM

  The aim of this study was to find the oral isolate of lactobacilli, which has the potential to inhibit either periodontal, cariogenic, or fungal pathogens in vitro, and to examine the effects of bovine milk fermented with the isolate on the oral carriage of cariogenic and periodontal pathogens.

METHODS

  The inhibitory effects of the supernatant of Man-Rogosa-Sharpe broth, in which each of 42 oral isolates of lactobacilli grown, was examined. One isolate, Lactobacillus rhamnosus L8020, that showed the potential to inhibit either periodontal, cariogenic, or fungal pathogens in vitro, was used to examine the effects of fermented milk on the oral carriage of cariogenic and periodontal pathogens, which was examined by a placebo-controlled and cohort trial using 50 participants.

RESULTS

  Edible yogurt containing Lactobacillus rhamnosus L8020 significantly reduced the oral carriage of mutans streptococci (P < 0.01) and four periodontal pathogens examined: Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, and Fusobacterium spp. (P < 0.01), but the phenomenon were not observed with the placebo yogurt (P > 0.05).

CONCLUSION

  These results suggest that yogurt with Lactobacillus rhamnosus L8020 could reduce the risk of dental caries and periodontal disease.

Necrotizing fasciitis: a complication of percutaneous coronary revascularization

Percutaneous coronary revascularization is rarely complicated by infection. Necrotizing fasciitis (NF) is a severe, deep-seated, potentially life-threatening infection of fascia and subcutaneous tissues. We report herein 2 cases of NF in patients undergoing percutaneous transluminal coronary revascularization for treatment of acute coronary syndrome. These are the first 2 reported cases of NF associated with percutaneous coronary revascularization.

Genome sequence of Fusobacterium nucleatum subspecies polymorphum - a genetically tractable fusobacterium

Fusobacterium nucleatum is a prominent member of the oral microbiota and is a common cause of human infection. F. nucleatum includes five subspecies: polymorphum, nucleatum, vincentii, fusiforme, and animalis. F. nucleatum subsp. polymorphum ATCC 10953 has been well characterized phenotypically and, in contrast to previously sequenced strains, is amenable to gene transfer. We sequenced and annotated the 2,429,698 bp genome of F. nucleatum subsp. polymorphum ATCC 10953. Plasmid pFN3 from the strain was also sequenced and analyzed. When compared to the other two available fusobacterial genomes (F. nucleatum subsp. nucleatum, and F. nucleatum subsp. vincentii) 627 open reading frames unique to F. nucleatum subsp. polymorphum ATCC 10953 were identified. A large percentage of these mapped within one of 28 regions or islands containing five or more genes. Seventeen percent of the clustered proteins that demonstrated similarity were most similar to proteins from the clostridia, with others being most similar to proteins from other gram-positive organisms such as Bacillus and Streptococcus. A ten kilobase region homologous to the Salmonella typhimurium propanediol utilization locus was identified, as was a prophage and integrated conjugal plasmid. The genome contains five composite ribozyme/transposons, similar to the CdISt IStrons described in Clostridium difficile. IStrons are not present in the other fusobacterial genomes. These findings indicate that F. nucleatum subsp. polymorphum is proficient at horizontal gene transfer and that exchange with the Firmicutes, particularly the Clostridia, is common.

Contribution of proteases and plasmin-acquired activity in migration of Peptostreptococcus micros through a reconstituted basement membrane

BACKGROUND/AIMS

Peptostreptococcus micros is a gram-positive bacterium that has been associated with chronic periodontitis and endodontic infections. The aims of this study were to investigate the production of proteases and the acquisition of plasmin activity by rough and smooth morphotypes of P. micros. The contribution of these properties in the migration of bacteria through a reconstituted basement membrane was also evaluated.

METHODS

Protease activities were determined using chromogenic and fluorogenic substrates as well as by zymography. Plasminogen binding activity was studied using an enzyme-linked immunosorbent assay. The role of proteases and plasmin-acquired activity in tissue penetration was investigated using Matrigel.

RESULTS

The rough morphotype strains of P. micros, but not the smooth morphotype strains, were found to possess chymotrypsin-like and gelatinase activities, both of which were inhibited by a serine protease inhibitor. By zymography, three gelatinase bands (165, 129, and 115 kDa) were identified. Both morphotypes of P. micros can bind human plasminogen on their cell surface. Once bound to P. micros, plasminogen activators of bacterial (streptokinase) and human (urokinase) origins were found to activate plasminogen into plasmin. Our results also showed that plasmin activity can be acquired by P. micros following co-incubation with human brain microvascular endothelial cells in culture. When non-coated cells were used, the rough morphotype strain (HG1262), which possesses chymotrypsin-like and gelatinase activities, showed a better capacity to penetrate a reconstituted basement membrane (Matrigel) than the smooth morphotype strain (HG1251). Penetration of the Matrigel by P. micros HG1262 was inhibited by the presence of a serine protease inhibitor. In addition, cells of P. micros with plasmin activity showed a significantly greater tissue penetration capacity.

CONCLUSION

Our study suggests that endogenous proteolytic activities of P. micros as well as plasmin-acquired activity, may facilitate dissemination of bacterial cells to surrounding periodontal tissues and blood vessels.

Characterization of the novel Fusobacterium nucleatum plasmid pKH9 and evidence of an addiction system

Fusobacterium nucleatum is an important oral anaerobic pathogen involved in periodontal and systemic infections. Studies of the molecular mechanisms involved in fusobacterial virulence and adhesion have been limited by lack of systems for efficient genetic manipulation. Plasmids were isolated from eight strains of F. nucleatum. The smallest plasmid, pKH9 (4,975 bp), was characterized and used to create new vectors for fusobacterial genetic manipulation. DNA sequence analysis of pKH9 revealed an open reading frame (ORF) encoding a putative autonomous rolling circle replication protein (Rep), an ORF predicted to encode a protein homologous to members of the FtsK/SpoIIIE cell division-DNA segregation protein family, and an operon encoding a putative toxin-antitoxin plasmid addiction system (txf-axf). Deletion analysis localized the pKH9 replication region in a 0.96-kbp fragment. The pKH9 rep gene is not present in this fragment, suggesting that pKH9 can replicate in fusobacteria independently of the Rep protein. A pKH9-based, compact Escherichia coli-F. nucleatum shuttle plasmid was constructed and found to be compatible with a previously described pFN1-based fusobacterial shuttle plasmid. Deletion of the pKH9 putative addiction system (txf-axf) reduced plasmid stability in fusobacteria, indicating its addiction properties and suggesting it to be the first plasmid addiction system described for fusobacteria. pKH9, its genetic elements, and its shuttle plasmid derivatives can serve as useful tools for investigating fusobacterial properties important in biofilm ecology and pathogenesis.

Bacterial vaginosis - a microbiological and immunological enigma. Review article

The development of bacterial vaginosis (BV) among women of childbearing age and the resulting quantitative and qualitative shift from normally occurring lactobacilli in the vagina to a mixture of mainly anaerobic bacteria is a microbiological and immunological enigma that so far has precluded the formulation of a unifying generally accepted theory on the aetiology and clinical course of BV. This critical review highlights some of the more important aspects of BV research that could help in formulating new basic ideas respecting the biology of BV, not least the importance of the interleukin mediators of local inflammatory responses and the bacterial shift from the normally occurring lactobacilli species: L. crispatus, L. gasseri, L. jensenii, and L. iners to a mixed flora dominated by anaerobic bacteria.

Native plasmids of Fusobacterium nucleatum: characterization and use in development of genetic systems

Three native plasmids of Fusobacterium nucleatum were characterized, including DNA sequence analysis of one plasmid, pFN1. A shuttle plasmid, pHS17, capable of transforming Escherichia coli and F. nucleatum ATCC 10953 was constructed with pFN1. pHS17 was stably maintained in the F. nucleatum transformants, and differences in the transformation efficiencies suggested the presence of a restriction-modification system in F. nucleatum.

Destructive knee joint infection caused by Peptostreptococcus micros: importance of early microbiological diagnosis

Peptostreptococcus micros is a commensal of the oral cavity and the genitourinary tract that rarely causes serious infections. A case of a destructive knee joint infection with rapid progress caused by P. micros is presented. The significance of the microbiological findings was initially not acknowledged, which contributed to a nonsuccessful clinical outcome.