Inhibition of experimental periodontitis by a monoclonal antibody against Porphyromonas gingivalis HA2

It is known that complexes of the multi-protein, gingipain, possess heme binding domains (hemagglutinin 2, HA2) that bind hemoglobin to provide heme and iron to the bacterium, Porphyromonas gingivalis. The DHYAVMISK peptide sequence was proposed to act as an inhibitor of hemin binding, and thus, it might be used to control or prevent periodontal disease. In this study, we created a monoclonal antibody (mAb) that targeted the DHYAVMISK peptide, aimed to determine whether it could inhibit the growth of P. gingivalis in vitro, and block its induction of experimental periodontitis and subsequent bone loss. Peptide DGFPG-DHYAVMISK conjugated to KLH (DK-KLH) was synthetic, and injected subcutaneously into BALB/c mice to generate specific mAbs with the hybridoma technique. We isolated mAb 1H11, which showed specific binding to DK. When we incubated these mAbs with P. gingivalis in vitro for 18 h, bacterial growth was significantly lower in cultures treated with mAb 1H11 compared to those treated with control (PBS; P < 0.05). Next, we induced experimental periodontitis in mouse models with a silk ligature and a P. gingivalis infection. When we injected the mAbs into the gingival sulcus, the group treated with mAb 1H11 displayed a reduction in bone loss compared to the other treatment groups. Thus, mAb 1H11 might provide protection against a P. gingivalis infection. Accordingly, this antibody could serve as a candidate therapy for periodontitis or other infections caused by P. gingivalis.

[Promotion of Porphyromonas gingivalis to viral disease]

Chronic periodontitis is one of the most common oral diseases in humans, the main recognized pathogenic bac-terium of which is the Porphyromonas gingivalis. Various types of viruses have been detected in periodontal disease in situ, and the joint action of viral and bacterial pathogens infection mechanism are complicated. Porphyromonas gingivalis has the characteristics resulting from the interaction with a variety of bacterium viruses, which may be the reason for chronic perio-dontitis being a protracted disease associated with a variety of systemic diseases. In this paper, we reviewed the relationship between Porphyromonas gingivalis and viral diseases to provide a new idea for the treatment of patients with periodontal disease and viral infections.

Retropharyngeal abscess complicated by Prevotella buccae sepsis during pregnancy. A case report

BACKGROUND

Retropharyngeal abscess is extremely uncommon in adults and rare in pregnancy. A MEDLINE search yielded only 1 reported case during pregnancy. Likewise, sepsis caused by prevotella buccae, a bacteria associated with more benign conditions such as bacterial vaginosis or dental infections, is also rare, with no reported cases during pregnancy.

CASE

We report a case of retropharyngeal abscess complicated by Prevotella buccae septicemia during pregnancy.

CONCLUSION

Retropharyngeal abscess should be suspected in a pregnant patient who presents with sore throat, dyspnea, and dysphagia, especially when preceded by dental treatment or symptoms. If confirmed, antibiotic treatment should cover the usual pathogens associated with retropharyngeal abscess, including Pre- votella species.

Interactions of adiponectin and lipopolysaccharide from Porphyromonas gingivalis on human oral epithelial cells

BACKGROUND

Periodontitis is an inflammatory disease caused by pathogenic microorganisms, such as Porphyromonas gingivalis, and characterized by the destruction of the periodontium. Obese individuals have an increased risk for periodontitis and show decreased serum levels of adiponectin. This in-vitro study was established to examine whether adiponectin modulates critical effects of lipopolysaccharide (LPS) from P. gingivalis on oral epithelial cells (OECs).

METHODOLOGY/PRINCIPAL FINDINGS

The presence of adiponectin and its receptors in human gingival tissue samples and OECs was analyzed by immunohistochemistry and PCR. Furthermore, OECs were treated with LPS and/or adiponectin for up to 72 h, and the gene expression and protein synthesis of pro- and anti-inflammatory mediators, matrix metalloproteinases (MMPs) and growth factors were analyzed by real-time PCR and ELISA. Additionally, cell proliferation, differentiation and in-vitro wound healing were studied. The nuclear translocation of NFκB was investigated by immunofluorescence. Gingival tissue sections showed a strong synthesis of adiponectin and its receptors in the epithelial layer. In cell cultures, LPS induced a significant up-regulation of interleukin (IL) 1β, IL6, IL8, MMP1 and MMP3. Adiponectin abrogated significantly the stimulatory effects of LPS on these molecules. Similarly, adiponectin inhibited significantly the LPS-induced decrease in cell viability and increase in cell proliferation and differentiation. Adiponectin led to a time-dependent induction of the anti-inflammatory mediators IL10 and heme oxygenase 1, and blocked the LPS-stimulated NFκB nuclear translocation.

CONCLUSIONS/SIGNIFICANCE

Adiponectin may counteract critical actions of P. gingivalis on oral epithelial cells. Low levels of adiponectin, as observed in obese individuals, may increase the risk for periodontal inflammation and destruction.

Unique structure and stability of HmuY, a novel heme-binding protein of Porphyromonas gingivalis

Infection, survival, and proliferation of pathogenic bacteria in humans depend on their capacity to impair host responses and acquire nutrients in a hostile environment. Among such nutrients is heme, a co-factor for oxygen storage, electron transport, photosynthesis, and redox biochemistry, which is indispensable for life. Porphyromonas gingivalis is the major human bacterial pathogen responsible for severe periodontitis. It recruits heme through HmuY, which sequesters heme from host carriers and delivers it to its cognate outer-membrane transporter, the TonB-dependent receptor HmuR. Here we report that heme binding does not significantly affect the secondary structure of HmuY. The crystal structure of heme-bound HmuY reveals a new all-β fold mimicking a right hand. The thumb and fingers pinch heme iron through two apical histidine residues, giving rise to highly symmetric octahedral iron co-ordination. The tetrameric quaternary arrangement of the protein found in the crystal structure is consistent with experiments in solution. It shows that thumbs and fingertips, and, by extension, the bound heme groups, are shielded from competing heme-binding proteins from the host. This may also facilitate heme transport to HmuR for internalization. HmuY, both in its apo- and in its heme-bound forms, is resistant to proteolytic digestion by trypsin and the major secreted proteases of P. gingivalis, gingipains K and R. It is also stable against thermal and chemical denaturation. In conclusion, these studies reveal novel molecular properties of HmuY that are consistent with its role as a putative virulence factor during bacterial infection.

Pathogenic bacteria cause infection in humans as found in periodontitis, which is a chronic inflammation of the gums caused by Porphyromonas gingivalis. As part of the infective process, bacteria must acquire nutrients to survive and multiply at the infection site, and among such nutrients is heme. This is an iron-dependent co-factor of several indispensable enzymes and proteins. P. gingivalis liberates heme from host heme-binding proteins through the action of proteases and arranges its transport to the bacterial cell through two proteins, HmuY and HmuR. They grab free heme and transport it across the bacterial membrane into the cell, respectively. This function poses stringent conditions on these proteins regarding stability and resistance toward the host immune system. We report here that HmuY is very stable and that it displays a novel protein fold, which consists only of β-strands. It reminds us of a right hand, whose fingers trap heme. Once heme is bound, HmuY forms tetramers, which have the four heme-binding sites buried and thus protected from competing host heme-binding proteins. This feature also facilitates heme transport to HmuR and into the bacterial cell. All these data may help to develop new antibacterial agents at times in which resistance toward antibiotics, both at intensive healthcare stations and in the community, poses serious challenges to human health.

Cutting Edge: TLR2 is required for the innate response to Porphyromonas gingivalis: activation leads to bacterial persistence and TLR2 deficiency attenuates induced alveolar bone resorption

Periodontitis is a chronic inflammatory disease that leads to destruction of the attachment apparatus of the teeth. The presence of particular oral bacteria and the host inflammatory response contribute to disease progression. Porphyromonas gingivalis is a Gram-negative anaerobe considered to be a major periodontal pathogen. Isolated Ags from P. gingivalis activate innate immune cells through TLR2 or TLR4. We challenged TLR2- and TLR4-deficient mice with live P. gingivalis and studied the inflammatory response and bacterial survival. Wild-type and TLR4-deficient mice produced high levels of cytokines in response to P. gingivalis challenge, whereas cytokine levels were nearly absent or delayed in TLR2-deficient mice. Surprisingly, P. gingivalis was cleared far more rapidly in TLR2-deficient mice. In addition, TLR2-deficient mice resisted bone loss following oral infection with P. gingivalis.

Infection with a periodontal pathogen increases mononuclear cell adhesion to human aortic endothelial cells

BACKGROUND

As a link between periodontal infections and an increased risk for vascular disease has been demonstrated, we assessed the ability of the Gram-negative periodontal pathogen Porphyromonas gingivalis to modulate properties of endothelial cells linked to inflammation and proatherogenic pathways.

METHODS AND RESULTS

Primary human aortic endothelial cells (HAEC) were infected with either P. gingivalis strain 381 or its non-invasive fimbriae-deficient mutant, DPG3, and incubated with U-937 monocytes, or Jurkat T cells. P. gingivalis-infected HAEC demonstrated significantly increased adhesion of immune cells compared to non-infected cells or those infected with DPG3. Heat-killed bacteria had no effect on mononuclear cell adhesion and P. gingivalis LPS had only a minimal effect. P. gingivalis infection significantly increased HAEC expression of VCAM-1, ICAM-1 and E-selectin, and enhanced production of IL-6, IL-8 and MCP-1.

CONCLUSION

These data demonstrate that live invasive P. gingivalis 381 elicits a pro-atherogenic response in HAEC.

[Colonization relationship between Porphyromonas gingivalis and Bacteroides forsythus in the infected root canals with chronic apical periodontitis]

PURPOSE

To detect the distribution of P. gingivalis and B. forsythus in the infected root canals from Chinese chronic apical periodontitis, and investigate the colonization relationship between them in the root canals.

METHODS

P. gingivalis and B. forsythus in the root canal samples of thirty-eight teeth with chronic apical periodontitis from 31 subjects who were referred to the Sichuan University West China Dental Hospital for dental treatment were studied with a 16S rDNA-directed polymerase chain reaction method. Fisher's exact tset was used to detect B. forsythus in the infected root canals with or without P. gingivalis. OR was used to analyse the relationship between them.

RESULTS

The prevalence in 38 teeth was 39.5% for P. gingivalis, and 26.3% for B. forsythus, respectively. Significant positive relationship was shown in the combination of P. gingivalis and B. forsythus (OR=12, P<0.05).

CONCLUSION

Both P. gingivalis and B. forsythus colonized in the root canals with chronic apical periodontitis and there was a positive relationship between P. gingivalis and B. forsythus in the infected root canal flora.

Sequence variations in rgpA and rgpB of Porphyromonas gingivalis in periodontitis

OBJECTIVE

The aim of the present study was to determine sequence variations in the active centre of the Arg-X-specific protease encoding genes rgpA and rgpB of clinical Porphyromonas gingivalis isolates and to analyse their prevalence in periodontitis patients before and 3 months after mechanical periodontal therapy.

BACKGROUND

Genetic diversity at nucleotides 281, 283, 286 and 331 has been shown to result in amino acid substitutions in the catalytic domain of RgpA and RgpB that affect the substrate specificity and thus may influence the efficacy of Arg-X-protease specific inhibitors.

METHODS

Sequence analysis of rgpA and rgpB genes in clinical P. gingivalis strains isolated from subgingival plaque samples of 82 periodontitis patients before and 3 months after mechanical supra- and subgingival debridement was performed.

RESULTS

No specific variation within the rgpA sequence was observed. However, the rgpB sequence in the region of the active centre showed five different rgpB genotypes, which were named NYPN, NSSN, NSSK, NYPK and DYPN according to the derived amino acid substitution. Porphyromonas gingivalis genotype NYPN was detected in 27 patients (32.9%) before and in 8 patients (9.8%) after therapy, NSSN in 26 (31.7%) and 10 (12.2%), NSSK in 22 (26.8%) and 2 (2.4%), NYPK in 5 (6.2%) and 1 (1.2%), and DYPN in 1 patient (1.2%) and 0 patients (0%), respectively. Only one patient (1.2%) harboured two P. gingivalis rgpB genotypes (NSSK/NYPN) before treatment; these were no longer detected after therapy.

CONCLUSION

The results indicate that five rgpB genotypes are maintained in natural populations of P. gingivalis. These data may be of importance with regard to the development of specific rgpB inhibitors.

Biological foundation for periodontitis as a potential risk factor for atherosclerosis

OBJECTIVES

Links between periodontal diseases and systemic diseases have been well documented by epidemiological studies. Recently, research has shifted to elucidating the biologic mechanism for a causal relationship. One focus of interest is atherosclerosis, the underlying event of cardiovascular diseases due to its serious health impact. However, it is still not clear whether periodontopathic pathogens are truly etiologic agents or ubiquitous bystanders. This article reviews the current understanding about the molecular biological interactions between periodontal disease and atherosclerosis and the biological plausibility of periodontitis as a potential risk factor for cardiovascular disease.

MATERIALS AND METHODS

The current literature regarding periodontal diseases and atherosclerosis and coronary vascular disease was searched using the Medline and PubMed databases.

RESULTS

In vitro experiments and animal models are appropriate tools to investigate the biological interactions between periodontal disease and atherosclerosis at the cell molecular level. The concepts linking both pathologies refer to inflammatory response, immune responses, and hemostasis. In particular, Porphyromonas gingivalis appears to have unique, versatile pathogenic properties. Whether or not these findings from isolated cells or animal models are applicable in humans with genetic and environmental variations is yet to be determined. Likewise, the benefit from periodontal therapy on the development of atherosclerosis is unclear. Approaches targeting inflammatory and immune responses of periodontitis and atherosclerosis simultaneously are very intriguing.

CONCLUSION

An emerging concept suggests that a pathogenic burden from different sources might overcome an individual threshold culminating in clinical sequela. P. gingivalis contributes directly and indirectly to atherosclerosis.

[A comparative study utilizing different methods for establishing an experimental periodontitis model in rats]

OBJECTIVE

To evaluate the experimental periodontitis in rats induced by ligature plus high sugar water with and without infection of periodontopathic bacteria.

METHODS

Forty SD rats (5 weeks of age) were randomly divided into a control group (N) and three experimental groups (P1, P2 and P3). All experimental groups were given silk ligatures around the cervix of the second maxillary molars and were provided with drinking water containing 10% glucose. Group P2 was inoculated with P. gingivalis, three times; group P3 was inoculated with P. gingivalis and F. nucleatum, three times. At weeks 0, 2 and 4, microbiological and histological examinations were made; alveolar bone loss was stereoscopically measured as the distance from the cement-enamel junction to the alveolar crest.

RESULTS

Microbiological examination indicated that the bacteria inoculated in groups P2 and P3 were successfully colonized and both of P. gingivalis and F. nucleatum were predominant among the bacterial colonies of the examined sites. At week 2, histological examination showed gingival erosion and alveolar bone loss in all experimental groups and periodontal pockets in groups P2 and P3. The most serious lesions were observed in group P3. At week 4, the periodontal destruction in all experimental groups became more severe.

CONCLUSION

Ligature, high sugar water combined with mixed infection of periodontopathic bacteria can successfully induce experimental periodontitis in rats.

Treponema socranskii, Treponema denticola, and Porphyromonas gingivalis are associated with severity of periodontal tissue destruction

BACKGROUND

The aim of the present study was to identify Treponema socranskii in addition to Treponema denticola and Porphyromonas gingivalis by polymerase chain reaction (PCR), and to clarify the relationship between the presence of these microorganisms and the severity of clinical periodontal parameters.

METHODS

Saliva and subgingival plaque collected from 123 subjects (38 aggressive periodontitis patients, 65 chronic periodontitis patients, 20 healthy patients) were subjected to PCR to detect the aforementioned 3 microorganisms.

RESULTS

Detection frequencies of T. socranskii, T. denticola, and P. gingivalis in plaque samples from aggressive periodontitis patients (71.1%, 73.7%, 84.2%, respectively) and chronic periodontitis patients (89.2%, 93.8%, 95.3%) were much higher than those from healthy subjects (30%, 5.0%, 10.0%). In aggressive and chronic periodontitis patients, these 3 species of bacteria were detected frequently at sites that showed deep periodontal pockets and severe attachment loss. The percentage of these bacteria-positive sites increased as the gingival index score of chronic periodontitis patients increased. T. socranskii was frequently detected together with T. denticola or P. gingivalis at the same sites, and coexistence of these microorganisms was frequently observed in deep periodontal pockets of aggressive periodontitis patients.

CONCLUSIONS

T. socranskii, T. denticola, and P. gingivalis were frequently detected in periodontitis patients by PCR. The prevalence of these 3 microorganisms was correlated with various clinical parameters. Taken together, our findings suggest that T. socranskii, T. denticola, and P. gingivalis are associated with the severity of periodontal tissue destruction.

Activation of protease-activated receptors by gingipains from Porphyromonas gingivalis leads to platelet aggregation: a new trait in microbial pathogenicity

The bacterium Porphyromonas gingivalis is a major etiologic agent in the pathogenesis of adult periodontitis in humans. Cysteine proteinases produced by this pathogen, termed gingipains, are considered to be important virulence factors. Among many other potentially deleterious activities, arginine-specific gingipains-R (RgpB and HRgpA) efficiently activate coagulation factors. To further expand knowledge of the interaction between gingipains and the clotting cascade, this study examined their effects on cellular components of the coagulation system. The enzymes induced an increase in intracellular calcium in human platelets at nanomolar concentrations and caused platelet aggregation with efficiency comparable to thrombin. Both effects were dependent on the proteolytic activity of the enzymes. Based on desensitization studies carried out with thrombin and peptide receptor agonists, and immunoinhibition experiments, gingipains-R appeared to be activating the protease-activated receptors, (PAR)-1 and -4, expressed on the surface of platelets. This was confirmed by the finding that HRgpA and RgpB potently activated PAR-1 and PAR-4 in transfected cells stably expressing these receptors. Cumulatively, the results indicate the existence of a novel pathway of host cell activation by bacterial proteinases through PAR cleavage. This mechanism not only represents a new trait in bacterial pathogenicity, but may also explain an emerging link between periodontitis and cardiovascular disease. (Blood. 2001;97:3790-3797)

Soluble antagonists to interleukin-1 (IL-1) and tumor necrosis factor (TNF) inhibits loss of tissue attachment in experimental periodontitis

BACKGROUND, AIMS

Periodontal disease is a significant cause of tooth loss among adults and is characterized by the alteration and permanent destruction of the deeper periodontal tissues. Although the presence of pathologic microbes is required to trigger this process, the amplification and progression of the diseased state is believed to rely heavily on the production of host mediators in response to bacteria or their metabolic products. The inflammatory response is effective in preventing large-scale colonization of the gingival tissues by bacteria that lie in close proximity to the tooth surface or within the gingival sulcus. It has been postulated that the host-response in some individuals may lead to an over-reaction to invading oral pathogens resulting in the destruction of periodontal tissues.

METHODS

Several host-derived mediators are believed to contribute to this response. Two agents considered to be essential in periodontal destruction are interleukin-1 (IL-1) and tumor necrosis factor (TNF). We investigated the role of IL-1 and TNF in the loss of connective tissue attachment in a Macaca fascicularis primate model of experimental periodontitis. Silk ligatures impregnated with the periodontal pathogen, Porphyromonas gingivalis were wrapped around the posterior teeth and the activity of IL-1 and TNF were inhibited by soluble receptors to these proinflammatory cytokines via local injection into interdental papillae.

RESULTS

Histomorphometric analysis indicates that IL-1 and TNF antagonists significantly reduced the loss of connective tissue attachment by approximately 51% and the loss of alveolar bone height by almost 91%, both of which were statistically significant.

CONCLUSION

This investigation demonstrates that the loss of connective tissue attachment and progression of periodontal disease can be retarded by antagonists to specific host mediators such as IL-1 and TNF and may provide a potential treatment modality to combat the disease process.

[A case of anterior mediastinal abscess with skin fistula resulting from descending necrotizing mediastinitis]

Descending necrotizing mediastinitis (DNM) is a serious, life-threatening infection. We present a case of anterior mediastinal abscess resulting from DNM. A 43-year-old woman, who had underwent cervical drainage for DNM 4 months ago, visited our hospital for cervical fistula. Chest CT revealed anterior mediastinal abscess. Mediastinal drainage through a subxiphoidal incision, debridement via the parasternal approach and resection of cervical fistula were performed without thoracotomy. A continuous mediastinal irrigation by acid water was performed postoperatively. The culture of the drain fluid became negative, and mediastinal abscess was disappeared. In conclusion, immediate and suitable drainage, debridement and postoperative-irrigation are important for DNM. On chronic stage, management to defend from extending infection is needed.

Occurrence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia in progressive adult periodontitis

BACKGROUND

Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia are the major periodontal bacteria species in most forms of progressive periodontitis in Scandinavia and the United States. The occurrence of periodontal pathogens appears to be different in subjects of different ethnic origin, and geographical factors may influence the distribution of these species.

METHODS

The occurrence of A. actinomycetemcomitans, P. gingivalis, and P. intermedia was determined using a DNA probe in progressive adult periodontitis in Chileans. Sixty patients (mean age 43.6 +/- 8 years) who had not previously received any type of periodontal therapy were selected. Bleeding on probing, probing depth, and clinical attachment level measurements were made with an automated probe. Patients were monitored at 2-month intervals until at least 2 sites exhibited > or =2 mm attachment loss. Two subgingival plaque samples from active sites were taken in 56 subjects and matched with 2 plaque samples from inactive sites in the same individuals.

RESULTS

P. gingivalis was found in 75% of active sites and in 59.7% of inactive sites in 96% of the patients (P = 0.022). P. gingivalis at high levels of detection was significantly more frequent in active sites (48.2%) than in inactive sites (31.2%) (P = 0.014). A. actinomycetemcomitans was detected in 6.25% of active sites and in 12.5% of inactive sites in 11.6% of patients. P. intermedia was found in 33% of patients and at a significantly higher proportion in active sites (49.1%) than in inactive sites (30.3%) (P = 0.006). There was a significantly higher proportion of inactive sites (34.8%) than active sites (19.6%) without any of the 3 pathogens (P = 0.016). Bleeding on probing was significantly more associated with active sites with high levels of P. gingivalis and with active sites with P. intermedia than with inactive sites.

CONCLUSIONS

A high prevalence of P. gingivalis and P. intermedia was found in adult periodontitis, and the occurrence of these bacteria appears to be higher in Chileans than in other populations. No apparent association exists between A. actinomycetemcomitans and progressive adult periodontitis in Chileans.

Human herpesviruses and Porphyromonas gingivalis are associated with juvenile periodontitis

BACKGROUND

Although herpesviruses have been associated with adult periodontitis, their relationship with juvenile periodontitis (JP) has not been established. This case-control study examined possible associations between JP and pathogenic bacteria, the human cytomegalovirus (HCMV), and the Epstein-Barr type 1 virus (EBV-1).

METHODS

Subjects were participants in a larger survey of schoolchildren in North-Central Jamaica. Subgingival plaque samples from 15 subjects with JP, 20 with incipient periodontitis (IP), and 65 randomly-selected healthy controls were assayed for Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans using a 16S rRNA polymerase chain reaction (PCR) identification method, and for HCMV and EBV-1 using nested PCR identification.

RESULTS

Strong bivariate associations were found between JP and P. gingivalis (odds ratio [OR] = 12.7; 95% CI = 2.6, 61.4), HCMV (OR = 10.0; 95% CI = 2.7, 36.3), and A. actinomycetemcomitans (OR = 8.0; 95% CI = 2.3, 27.5), but not EBV-1. In multivariate analyses, P. gingivalis remained a significant explanatory variable (OR = 7.8; 95% CI = 1.5, 40.9); however, the associations were marginal for HCMV (OR = 4.6; 95% CI = 0.9, 22.7), and non-significant for A. actinomycetemcomitans (OR = 2.0; 95% CI = 0.4, 9.7). The associations with JP and the extent of attachment loss were even stronger when both P. gingivalis and HCMV were detected together. P. gingivalis (OR = 3.9; 95% CI = 1.3, 12.0) and EBV-1 (OR = 3.3; 95% CI = 1.0, 10.3) were the only significant explanatory variables in the multivariate analysis of IP.

CONCLUSIONS

P. gingivalis is the strongest and most stable indicator of periodontitis in Jamaican adolescents. Co-infection with P. gingivalis and HCMV appears to be particularly deleterious to periodontal health.

Pyomyositis of the thigh due to Prevotella melaninogenica

Pyomyositis is an uncommon infection in temperate climates, however, it is being more frequently reported among patients with diabetes or malignancy, or those who are immunocompromised. It is predominantly caused by Staphylococcus aureus, and rarely by Bacteroides species. Pyomyositis due to Prevotella melaninogenica has not previously been reported. We describe an elderly patient with pyomyositis of the thigh due to P. melaninogenica which was successfully treated by surgical incision and drainage in combination with metronidazole therapy.

Periodontal status and subgingival microbiota of insulin-dependent juvenile diabetics: a 3-year longitudinal study

This study examined for 3 years the changes in periodontal status and the possible correlations with selected subgingival microbiota and diabetic conditions in a group of 16 insulin-dependent diabetes mellitus (IDDM, JD) patients as compared with their 16 healthy cohabiting siblings (HS). JD patients were monitored every 3 months for levels of glycosylated hemoglobin (HbA1C). Clinical and microbiological parameters were measured 6 weeks before drawing blood to determine levels of HbA1C. Periodontal parameters were measured at baseline (TO), year 2 (T2), year 3 (T3) and included: probing depth (PD), attachment level (AL), sulcus bleeding index (SBI), and plaque index (PI). Two sites in each patient were selected for microbial samples: a mesio-facial aspect of the maxillary right first molar (defined as constant site, CS) and a site with the greatest probing depth (defined as deepest site, DS). Microbial samples were analyzed by culture techniques. No significant differences in clinical parameters were found between diabetics and healthy siblings at any examination. The SBI in the non-diabetic group at T2 and at T3 was significantly lower than at baseline. PD and AL of constant sites in the diabetic group at T3 were significantly higher than baseline. There was a significant increase in Prevotella intermedia at T3 as compared with baseline for deepest sites in the diabetic group. Cluster analysis revealed, in a former study, two clusters (IV and V) at baseline which were significantly different from the overall mean regarding composition of Porphyromonas gingivalis and Capnocytophaga spp. They were not significantly different for periodontal parameters from TO to T3. These data would suggest no significant differences in clinical parameters between the diabetics and non-diabetic siblings throughout this 3-year longitudinal study.

The expression of collagen I and XII mRNAs in Porphyromonas gingivalis-induced periodontitis in rats: the effect of doxycycline and chemically modified tetracycline

Tissue remodeling is a dynamic state in which a balance is achieved between the proteolytic breakdown and synthesis of the extracellular matrix. Type I collagen is a major component of the gingival connective tissue (GCT) and the periodontal ligament (PDL) throughout development, while type XII collagen has been found in the mature forms of these tissues. The purpose of this study was to investigate the effects of periodontitis on the expression of type I and XII collagen and subsequently to investigate the effects of doxycycline (DOXY) and chemically modified non-antimicrobial tetracycline (CMT-1) on the expression of these molecules in this model. Adult barrier-raised male Sprague-Dawley rats were inoculated with Porphyromonas gingivalis obtained from humans to create the experimental periodontitis. The animals with the P. gingivalis-induced periodontitis were then split into the following groups: Group A served as infected untreated controls (PGI group); group B was treated with doxycycline (DOXY group); and group C was treated with chemically modified tetracycline-1 (CMT-1 group). Group D contained uninfected animals that served as uninfected controls (NIC group). The expression of type I and XII collagen mRNAs was examined by in situ hybridization in each group, with the co-expression of these molecules representing mature and functional gingival connective tissue. In the NIC group, cells hybridized with digoxygenine-labeled cDNA probes encoding rat alpha2(I) or alpha1(XII) collagens were found distributed uniformly throughout the periodontal connective tissue. The PGI group showed little hybridization in the areas of infection, while both the DOXY and CMT-1 groups showed co-expression of the alpha2(I) and alpha1(XII) probes in the GCT and coronal part of the PDL. This study demonstrates that doxycycline and CMT-1 moderate or reduce the inhibitory effects of periodontal infection on the expression of type I and type XII collagen mRNAs. These results suggest that doxycycline and a form of non-antimicrobial tetracycline, chemically modified tetracycline-1, can reduce periodontal destruction by reversing the inhibitory effect of periodontal infection on collagen synthesis.

Bacteraemia caused by periodontal probing

Bacteraemia of oral origin may result in infective endocarditis in susceptible individuals. The aim of this pilot study was to investigate the occurrence of bacteraemia due to periodontal probing. Thirty patients (15 male, 15 female; mean age 42.7 years) with untreated periodontitis were investigated. All were free of significant medical disorders and none had taken antibiotics in the previous month. Prior to and immediately following periodontal probing, 20 mL of venous blood were obtained from each patient and inoculated into aerobic and anaerobic blood culture bottles and incubated. Negative bottles were monitored continuously for three weeks before being discarded. Periodontal probing consisted of measuring pockets at six points around each tooth and recording the presence or absence of bleeding. A positive bacteraemia was recorded for three of the patients prior to probing. One patient exhibited Prevotella species whilst two exhibited skin commensals. Following probing, 13 patients (43 per cent) exhibited bacteraemia of oral origin. Viridans streptococci were the most common isolates (45 per cent). No significant correlations were found between bacteraemia and the severity of periodontitis or extent of bleeding on probing. The results indicate that periodontal probing can cause bacteraemia in patients with periodontitis. It would be advisable for patients considered at risk of developing infective endocarditis to receive antibiotic prophylaxis for periodontal probing if they have radiographic evidence of periodontitis.

[Intraabdominal polymicrobial infection due to antimicrobial resistant anaerobes]

Successful treatment of surgical infections includes both the implementation of careful operative technique and the choice of appropriate antimicrobial agent. Because of advances in the techniques used for anaerobic specimen collection and culture, anaerobic bacteria are now predominantly recovered from a variety of intra-abdominal and post-operative soft tissue infection. Furthermore, some anaerobes including Bacteroides and Prevotella, like some aerobic bacteria, have acquired resistance to the commonly used antimicrobial agent. The underestimation of resistant anaerobes other than Bacteroides in infective sites may lead to incorrect choices of antimicrobial agent for empirical therapy and thus to clinical failures of therapy. Surgeons should be more interested in the polymicrobial infecting flora to improve the clinical outcome of such infections.

Current view of risk factors for periodontal diseases

Peridontal diseases are infections, and many forms of the disease are associated with specific pathogenic bacteria which colonize the subgingival area. At least two of these microorganisms, Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans, also invade the periodontal tissue and are virulent organisms. Initiation and progression of periodontal infections are clearly modified by local and systemic conditions called risk factors. The local factors include pre-existing disease as evidenced by deep probing depths and plaque retention areas associated with defective restorations. Systemic risk factors recently have been identified by large epidemiologic studies using multifactorial statistical analyses to correct for confounding or associated co-risk factors. Risk factors which we know today as important include diabetes mellitus, especially in individuals in whom metabolic control is poor, and cigarette smoking. These two risk factors markedly affect the initiation and progression of periodontitis, and attempts to manage these factors are now an important component of prevention and treatment of adult periodontitis. Systemic conditions associated with reduced neutrophil numbers or function are also important risk factors in children, juveniles, and young adults. Diseases in which neutrophil dysfunction occurs include the lazy leukocyte syndrome associated with localized juvenile periodontitis, cyclic neutropenia, and congenital neutropenia. Recent studies also point to several potentially important periodontal risk indicators. These include stress and coping behaviors, and osteopenia associated with estrogen deficiency. There are also background determinants associated with periodontal disease including gender (with males having more disease), age (with more disease seen in the elderly), and hereditary factors. The study of risk in periodontal disease is a rapidly emerging field and much is yet to be learned. However, there are at least two significant risk factors-smoking and diabetes-which demand attention in current management of periodontal disease.

Cigarette smoking increases the risk for subgingival infection with periodontal pathogens

Cigarette smoking has been found to increase the risk for periodontitis. The present study examined the association between cigarette smoking and subgingival infection with periodontal pathogens to determine if smokers are more likely to be infected with certain periodontal pathogens than non-smokers. Self-reported data on 1,426 subjects, aged 25 to 74, from the Erie County Study were obtained including data on 798 subjects who were current or former smokers. Mean clinical attachment loss was used to estimate the severity of periodontal destruction. Subgingival infection with target periodontal pathogens was determined by indirect immunofluorescence microscopy. Smokers harbored significantly higher levels and were at significantly greater risk of infection with Bacteroides forsythus than non-smokers. Adjusting for disease severity, the risk of subgingival infection with B. forsythus in current smokers was 2.3 times that of former smokers or non-smokers. The relative risk of B. forsythus infection also increased 1.18 times for every category of smoking as the amount of smoking measured in packyears increased from very light to heavy. Adjusting for disease severity, Porphyromonas gingivalis was also more likely to subgingivally infect smokers than non-smokers; however, there was not a significantly higher relative risk for infection with this bacterium. The data from this study indicate that cigarette smoking increases the likelihood of subgingival infection with certain periodontal pathogens. This may partly explain the increased risk for periodontitis seen in smokers.

Aerobic and anaerobic microbiology of necrotizing fasciitis in children

Specimens obtained from eight children with necrotizing fasciitis (NF) were cultured for aerobic and anaerobic bacteria. A total of 21 isolates were recovered, 13 anaerobic and 8 aerobic or facultatives. The facultative organism Streptococcus pyogenes was present alone in two (25%) instances, and mixed aerobic and anaerobic bacteria were isolated in six (75%). The predominant isolates were Peptostreptococcus spp. (6 isolates, including 3 Peptostreptococcus magnus). S. pyogenes (4), Bacteroides fragilis group (3), Clostridium perfringens (2), Escherichia coli (2), and Prevotella spp. (2). Organisms similar to the ones isolated from the NF aspirates were recovered in the blood of all patients except one. These included S. pyogenes (3 isolates). B. fragilis group (2), E. coli (1), and P. magnus (1) and Clostridium perfringens (1). All patients underwent surgical fasciotomy, and four required skin grafting. Antimicrobials were administered to all children. Despite extensive resection and intense supportive therapy, three patients died from sepsis accompanied by shock acidosis and disseminated intravascular coagulation. These findings illustrate the polymicrobial aerobic-anaerobic flora of NF in children.

[Clinical analysis of bacterial vaginosis in 76 cases]

OBJECTIVE

To study the clinical manifestation and treatment of bacterial vaginosis (BV).

METHODS

The criteria used for diagnosis were the presence of clue cells by wet mount slide or gram stain, plus at least 2 of the following 3 signs and symptoms: (1) vaginal discharge with pH > 4.5; (2) an increased thin homogeneous vaginal discharge; (3) positive amine test. From 1994, 1 to 1995, 3, a total of 76 cases with BV who had good follow up were diagnosed and treated by Kejunning (a combination of chinese traditional herb medicine), Shuangzuotai (combined metronidazole vaginal suppository), metronidazole, etc.

RESULTS

For BV, the presence of clue cells is a prerequisite for diagnosis. Vaginal discharge with pH > 4.5 and positive amine test were present in all the cases. Increased white thin homogeneous vaginal fluid were found in 96.1% (73/76) of the cases. 79.0% of the patients complained of fishy odor vaginal discharge. Treatment with antibiotics or Shuangzuotai were effective. Kejunning had a cure rate of 70.0% one month after treatment.

CONCLUSIONS

The detection of clue cell is an important diagnostic criterion. Besides metronidazole, Kejunning had a good result for the treatment of BV as well.

The prevalence of A. actinomycetemcomitans, P. gingivalis and P. intermedia in selected subjects with periodontitis

The present study was carried out in a private periodontal practice. 8 clinical criteria were chosen to select patients for microbiological examination. These criteria characterize prominent features of disease which at the start, during, or in the maintenance phase of treatment suggest difficulties in the progress of the periodontal therapy. Based on these clinical characteristics, an inventory was made of the prevalence of the 3 putative periodontal pathogens: Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia. Out of 320 referred patients 91 patients did meet > or = 1 of the clinical criteria and consequently were selected for microbiological examination. Results showed that young patients (19-30 years) with periodontitis demonstrated the presence of A. actinomycetemcomitans more often (69%: p < 0.005) compared to older age cohorts. A. actinomycetemcomitans was found more often when localized breakdown (in particular in the 1st molar and incisor region) was observed and in patient who responded poorly to scaling and rootplaning. P. gingivalis and P. intermedia were most frequently recovered in patients showing primarily a bone loss pattern of angular defects of > or = 5 mm. Retrospectively, these patients were further categorized, based on full mouth radiographs, in (1) patients with primarily horizontal bone loss and (2) patients with primarily angular bony defects. Results showed that A. actinomycetemcomitans occurred less frequently in patients showing horizontal bone loss (p < 0.05).

Early evaluation of necrotizing fasciitis with use of CT

Gas bubbles are one of the important signs in the clinical diagnosis of necrotizing fasciitis, and radiographs are mandatory. An instance where gas bubbles not found on the plain radiographs were clearly shown by CT, which is a useful method for close monitoring and decompression of gas bubbles situated deeply in the spaces of the maxillo-facial and neck regions.