Bacteroides gracilis, an important anaerobic bacterial pathogen

Management of a Large Cerebral Abscess in Children Caused by Campylobacter gracilis: A Case Report and Review of the Literature

Campylobacter gracilis inhabits the gingival sulcus and has been reported to cause various periodontal diseases; it has rarely been reported to cause bacteremia. We describe a case of a two-year-old boy who presented with a consciousness disorder and was transferred to our hospital for treatment of a brain abscess. Magnetic resonance imaging (MRI) showed a 6-cm brain abscess in the right frontal lobe. Urgent drainage and antibiotic administration resulted in a favorable clinical course, and the patient was discharged on the 34th day of hospitalization. Streptococcus anginosus and C. gracilis were identified in the pus. Brain abscesses caused by C. gracilis have rarely been reported, which makes this a valuable case.

Infant diarrheal disease in rhesus macaques impedes microbiome maturation and is linked to uncultured Campylobacter species

Diarrheal diseases remain one of the leading causes of death for children under 5 globally, disproportionately impacting those living in low- and middle-income countries (LMIC). Campylobacter spp., a zoonotic pathogen, is one of the leading causes of food-borne infection in humans. Yet to be cultured Campylobacter spp. contribute to the total burden in diarrheal disease in children living in LMIC thus hampering interventions. We performed microbiome profiling and metagenomic genome assembly on samples collected from over 100 infant rhesus macaques longitudinally and during cases of clinical diarrhea within the first year of life. Acute diarrhea was associated with long-lasting taxonomic and functional shifts of the infant gut microbiome indicative of microbiome immaturity. We constructed 36 Campylobacter metagenomic assembled genomes (MAGs), many of which fell within 4 yet to be cultured species. Finally, we compared the uncultured Campylobacter MAGs assembled from infant macaques with publicly available human metagenomes to show that these uncultured species are also found in human fecal samples from LMIC. These data highlight the importance of unculturable Campylobacter spp. as an important target for reducing disease burden in LMIC children.

Gut dysbiosis is associated with aortic aneurysm formation and progression in Takayasu arteritis

BACKGROUND

Takayasu arteritis (TAK) is an autoimmune large vessel vasculitis that affects the aorta and its major branches, eventually leading to the development of aortic aneurysm and vascular stenosis or occlusion. This retrospective and prospective study aimed to investigate whether the gut dysbiosis exists in patients with TAK and to identify specific gut microorganisms related to aortic aneurysm formation/progression in TAK.

METHODS

We analysed the faecal microbiome of 76 patients with TAK and 56 healthy controls (HCs) using 16S ribosomal RNA sequencing. We examined the relationship between the composition of the gut microbiota and clinical parameters.

RESULTS

The patients with TAK showed an altered gut microbiota with a higher abundance of oral-derived bacteria, such as Streptococcus and Campylobacter, regardless of the disease activity, than HCs. This increase was significantly associated with the administration of a proton pump inhibitor used for preventing gastric ulcers in patients treated with aspirin and glucocorticoids. Among patients taking a proton pump inhibitor, Campylobacter was more frequently detected in those who underwent vascular surgeries and endovascular therapy for aortic dilatation than in those who did not. Among the genus of Campylobacter, Campylobacter gracilis in the gut microbiome was significantly associated with clinical events related to aortic aneurysm formation/worsening in patients with TAK. In a prospective analysis, patients with a gut microbiome positive for Campylobacter were significantly more likely to require interventions for aortic dilatation than those who were negative for Campylobacter. Furthermore, patients with TAK who were positive for C. gracilis by polymerase chain reaction showed a tendency to have severe aortic aneurysms.

CONCLUSIONS

A specific increase in oral-derived Campylobacter in the gut may be a novel predictor of aortic aneurysm formation/progression in patients with TAK.

Pathogenomics of Emerging Campylobacter Species

Campylobacter is among the four main causes of gastroenteritis worldwide and has increased in both developed and developing countries over the last 10 years. The vast majority of reported Campylobacter infections are caused by Campylobacter jejuni and, to a lesser extent, C. coli; however, the increasing recognition of other emerging Campylobacter pathogens is urgently demanding a better understanding of how these underestimated species cause disease, transmit, and evolve. In parallel to the enhanced clinical awareness of campylobacteriosis due to improved diagnostic protocols, the application of high-throughput sequencing has increased the number of whole-genome sequences available to dozens of strains of many emerging campylobacters. This has allowed for comprehensive comparative pathogenomic analyses for several species, such as C. fetus and C. concisus These studies have started to reveal the evolutionary forces shaping their genomes and have brought to light many genomic features related to pathogenicity in these neglected species, promoting the development of new tools and approaches relevant for clinical microbiology. Despite the need for additional characterization of genomic diversity in emerging campylobacters, the increasing body of literature describing pathogenomic studies on these species deserves to be discussed from an integrative perspective. This review compiles the current knowledge and highlights future work toward deepening our understanding about genome dynamics and the mechanisms governing the evolution of pathogenicity in emerging Campylobacter species, which is urgently needed to develop strategies to prevent or control the spread of these pathogens.

The Clinical Importance of Campylobacter concisus and Other Human Hosted Campylobacter Species

Historically, Campylobacteriosis has been considered to be zoonotic; the Campylobacter species that cause human acute intestinal disease such as Campylobacter jejuni and Campylobacter coli originate from animals. Over the past decade, studies on human hosted Campylobacter species strongly suggest that Campylobacter concisus plays a role in the development of inflammatory bowel disease (IBD). C. concisus primarily colonizes the human oral cavity and some strains can be translocated to the intestinal tract. Genome analysis of C. concisus strains isolated from saliva samples has identified a bacterial marker that is associated with active Crohn's disease (one major form of IBD). In addition to C. concisus, humans are also colonized by a number of other Campylobacter species, most of which are in the oral cavity. Here we review the most recent advancements on C. concisus and other human hosted Campylobacter species including their clinical relevance, transmission, virulence factors, disease associated genes, interactions with the human immune system and pathogenic mechanisms.

Complete Genome Sequence of Campylobacter gracilis ATCC 33236T

The human oral pathogen Campylobacter gracilis has been isolated from periodontal and endodontal infections, and also from nonoral head, neck, or lung infections. This study describes the whole-genome sequence of the human periodontal isolate ATCC 33236^T (=FDC 1084), which is the first closed genome for C. gracilis.

Global Epidemiology of Campylobacter Infection

Campylobacter jejuni infection is one of the most widespread infectious diseases of the last century. The incidence and prevalence of campylobacteriosis have increased in both developed and developing countries over the last 10 years. The dramatic increase in North America, Europe, and Australia is alarming, and data from parts of Africa, Asia, and the Middle East indicate that campylobacteriosis is endemic in these areas, especially in children. In addition to C. jejuni, there is increasing recognition of the clinical importance of emerging Campylobacter species, including Campylobacter concisus and Campylobacter ureolyticus. Poultry is a major reservoir and source of transmission of campylobacteriosis to humans. Other risk factors include consumption of animal products and water, contact with animals, and international travel. Strategic implementation of multifaceted biocontrol measures to reduce the transmission of this group of pathogens is paramount for public health. Overall, campylobacteriosis is still one of the most important infectious diseases that is likely to challenge global health in the years to come. This review provides a comprehensive overview of the global epidemiology, transmission, and clinical relevance of Campylobacter infection.

Massive parallel sequencing provides new perspectives on bacterial brain abscesses

Rapid development within the field of massive parallel sequencing (MPS) is about to bring this technology within reach for diagnostic microbiology laboratories. We wanted to explore its potential for improving diagnosis and understanding of polymicrobial infections, using bacterial brain abscesses as an example. We conducted a prospective nationwide study on bacterial brain abscesses. Fifty-two surgical samples were included over a 2-year period. The samples were categorized as either spontaneous intracerebral, spontaneous subdural, or postoperative. Bacterial 16S rRNA genes were amplified directly from the specimens and sequenced using Ion Torrent technology, with an average of 500,000 reads per sample. The results were compared to those from culture- and Sanger sequencing-based diagnostics. Compared to culture, MPS allowed for triple the number of bacterial identifications. Aggregatibacter aphrophilus, Fusobacterium nucleatum, and Streptococcus intermedius or combinations of them were found in all spontaneous polymicrobial abscesses. F. nucleatum was systematically detected in samples with anaerobic flora. The increased detection rate for Actinomyces spp. and facultative Gram-negative rods further revealed several species associations. We suggest that A. aphrophilus, F. nucleatum, and S. intermedius are key pathogens for the establishment of spontaneous polymicrobial brain abscesses. In addition, F. nucleatum seems to be important for the development of anaerobic flora. MPS can accurately describe polymicrobial specimens when a sufficient number of reads is used to compensate for unequal species concentrations and principles are defined to discard contaminant bacterial DNA in the subsequent data analysis. This will contribute to our understanding of how different types of polymicrobial infections develop.

Diversity in the protein N-glycosylation pathways within the Campylobacter genus

The foodborne bacterial pathogen, Campylobacter jejuni, possesses an N-linked protein glycosylation (pgl) pathway involved in adding conserved heptasaccharides to asparagine-containing motifs of >60 proteins, and releasing the same glycan into its periplasm as free oligosaccharides. In this study, comparative genomics of all 30 fully sequenced Campylobacter taxa revealed conserved pgl gene clusters in all but one species. Structural, phylogenetic and immunological studies showed that the N-glycosylation systems can be divided into two major groups. Group I includes all thermotolerant taxa, capable of growth at the higher body temperatures of birds, and produce the C. jejuni-like glycans. Within group I, the niche-adapted C. lari subgroup contain the smallest genomes among the epsilonproteobacteria, and are unable to glucosylate their pgl pathway glycans potentially reminiscent of the glucosyltransferase regression observed in the O-glycosylation system of Neisseria species. The nonthermotolerant Campylobacters, which inhabit a variety of hosts and niches, comprise group II and produce an unexpected diversity of N-glycan structures varying in length and composition. This includes the human gut commensal, C. hominis, which produces at least four different N-glycan structures, akin to the surface carbohydrate diversity observed in the well-studied commensal, Bacteroides. Both group I and II glycans are immunogenic and cell surface exposed, making these structures attractive targets for vaccine design and diagnostics.

The clinical importance of emerging Campylobacter species

A growing number of Campylobacter species other than C. jejuni and C. coli have been recognized as emerging human and animal pathogens. Although C. jejuni continues to be the leading cause of bacterial gastroenteritis in humans worldwide, advances in molecular biology and development of innovative culture methodologies have led to the detection and isolation of a range of under-recognized and nutritionally fastidious Campylobacter spp., including C. concisus, C. upsaliensis and C. ureolyticus. These emerging Campylobacter spp. have been associated with a range of gastrointestinal diseases, particularly gastroenteritis, IBD and periodontitis. In some instances, infection of the gastrointestinal tract by these bacteria can progress to life-threatening extragastrointestinal diseases. Studies have shown that several emerging Campylobacter spp. have the ability to attach to and invade human intestinal epithelial cells and macrophages, damage intestinal barrier integrity, secrete toxins and strategically evade host immune responses. Members of the Campylobacter genus naturally colonize a wide range of hosts (including pets, farm animals and wild animals) and are frequently found in contaminated food products, which indicates that these bacteria are at risk of zoonotic transmission to humans. This Review presents the latest information on the role and clinical importance of emerging Campylobacter spp. in gastrointestinal health and disease.

Characterization of polybacterial clinical samples using a set of group-specific broad-range primers targeting the 16S rRNA gene followed by DNA sequencing and RipSeq analysis

The standard use of a single universal broad-range PCR in direct 16S rDNA sequencing from polybacterial samples leaves the minor constituents at risk of remaining undetected because all bacterial DNA will be competing for the same reagents. In this article we introduce a set of three broad-range group-specific 16S rDNA PCRs that together cover the clinically relevant bacteria and apply them in the investigation of 25 polybacterial clinical samples. Mixed DNA chromatograms from samples containing more than one species per primer group were analysed using RipSeq Mixed (iSentio, Norway), a web-based application for the interpretation of chromatograms containing up to three different species. The group-specific PCRs reduced complexity in the resulting DNA chromatograms and made the assay more sensitive in situations with unequal species concentrations. Together this allowed for identification of a significantly higher number of bacterial species than did standard direct sequencing with a single universal primer pair and RipSeq analysis (95 vs 51). The method could improve microbiological diagnostics for important groups of patients and can be established in any laboratory with experience in direct 16S rDNA sequencing.

Are dropped osteoarticular bone fragments safely reimplantable in vivo?

BACKGROUND

There are limited data detailing the appropriate management of nondisposable autologous osteoarticular fragments that have been contaminated by the operating room floor. The goal of the present study was to perform a comprehensive, three-phase investigation to establish an appropriate intraoperative algorithm for the management of the acutely contaminated, but nondisposable, autologous osteoarticular bone fragment.

METHODS

Phase I of the study was performed to quantify the rate of contamination and microbial profile of human osteoarticular fragments that were dropped onto the operating room floor (n = 162). Phase II was performed to assess the feasibility and optimal means of decontaminating 340 similar fragments that underwent controlled contamination with bacteria that were identified in Phase I; decontamination was performed with use of cleansing agents that are routinely available in an operating room. Phase III was performed to assess the effect of each decontamination process on fragment chondrocyte viability through histologic evaluation.

RESULTS

The contamination rate in Phase I was 70%. Coagulase-negative Staphylococcus was the most commonly cultured organism. In Phase II, varying exposure time to the chemical agents did not make a significant difference in decontamination rates. Mechanical scrubbing was superior to mechanical saline solution lavage (zero of fifty-six cultures compared with twenty of fifty-six cultures were positive for coagulase-negative Staphylococcus; p < 0.001). As a whole, bactericidal agents were found to be more effective decontaminating agents than normal saline solution. Povidone-iodine and 4% chlorhexidine gluconate were the most effective decontaminating agents, with none of the twenty-eight specimens that were decontaminated with each agent demonstrating positive growth on culture. Phase III demonstrated that the groups that were treated with normal saline solution and povidone-iodine retained the greatest number of live cells and the least number of dead cells. Mechanical scrubbing significantly decreased chondrocyte viability as compared with a normal saline solution wash (p < 0.05).

CONCLUSIONS

The majority of osteochondral fragments that contact the operating room floor produce positive bacterial cultures. Five minutes of cleansing with a 10% povidone-iodine solution followed by a normal saline solution rinse appears to provide the optimal balance between effective decontamination and cellular toxicity for dropped autologous bone in the operative setting.

Subgingival microbial profiles of smokers with periodontitis

The subgingival microbiome is largely uncultivated, and therefore, cultivation-based and targeted molecular approaches have limited value in examining the effect of smoking on this community. We tested the hypothesis that the subgingival biofilm is compositionally different in current and never-smokers by using an open-ended molecular approach for bacterial identification. Subgingival plaque from deep sites of current and never-smokers matched for disease was analyzed by 16S sequencing. Smokers demonstrated greater abundance of Parvimonas, Fusobacterium, Campylobacter, Bacteroides, and Treponema and lower levels of Veillonella, Neisseria, and Streptococcus. Several uncultivated Peptostreptococci, Parvimonas micra, Campylobacter gracilis, Treponema socranskii, Dialister pneumosintes, and Tannerella forsythia were elevated in this group, while Veillonella sp. oral clone B2, Neisseria sp. oral clone 2.24, Streptococcus sanguinis, and Capnocytophaga sp. clone AH015 were at lower levels. The microbial profile of smoking-associated periodontitis is distinct from that of non-smokers, with significant differences in the prevalence and abundance of disease-associated and health-compatible organisms.

Campylobacter concisus and other Campylobacter species in children with newly diagnosed Crohn's disease

BACKGROUND

Campylobacter concisus and other members of the Campylobacter genus have recently been suggested as possible etiological agents of Crohn's disease (CD). To further investigate this issue we determined the prevalence of these organisms in pediatric patients newly diagnosed with CD.

METHODS

DNA was extracted from fecal specimens collected from 54 children with CD, 27 noninflammatory bowel disease (non-IBD), and 33 healthy controls and subjected to polymerase chain reaction (PCR) sequencing.

RESULTS

Detection of C. concisus DNA using a newly developed PCR assay targeting the 16S rRNA gene of C. concisus showed that 65% (35/54) of fecal samples from CD children were positive, a prevalence significantly higher than that in the healthy (33%, 11/33, P = 0.008) and non-IBD controls (37%, 10/27, P = 0.03). The prevalence of all Campylobacter DNA using genus-specific primers in children with CD was 72% (39/54), which was significantly higher than the 30% (10/33, P = 0.0002) and 30% (8/27, P = 0.0003) observed in healthy and non-IBD controls, respectively.

CONCLUSIONS

Given the strengthening evidence for a significantly higher prevalence of C. concisus and other non-jejuni Campylobacter species in pediatric CD, investigation into the role of these non-jejuni Campylobacter species in the initiation of human IBD is clearly a priority.

Direct 16S rRNA gene sequencing from clinical specimens, with special focus on polybacterial samples and interpretation of mixed DNA chromatograms

RipSeq (iSentio, Bergen, Norway) is a web-based application for the analysis of mixed DNA chromatograms. It opens the possibility to analyze chromatograms obtained by direct 16S rRNA gene sequencing from polybacterial human clinical samples. In this study, we used direct 16S rRNA gene sequencing to investigate 264 samples from a wide range of suspected human bacterial infections. The sequence-based identification was compared with the results from routine culture-based identification. A total of 151 samples were positive by the first PCR, producing 85 pure and 66 mixed DNA chromatograms. All mixed chromatograms were analyzed by RipSeq, although seven were so complex that only the dominant bacterial sequences could be identified. In general, sequence-based identification detected a larger number of species than did culture for samples from patients who had received antibiotics prior to sample collection and for samples containing anaerobic bacteria. RipSeq made it possible to apply this supplementary diagnostic tool to typical polybacterial specimens, such as internal abscesses, pleural fluids, and bile.

Campylobacter species isolated from extra-oro-intestinal abscesses: a report of four cases and literature review

Campylobacter species are frequently isolated from fecal specimens of patients with diarrheal illness. Several Campylobacter species are commonly isolated from the oral cavity. In contrast, Campylobacter species are rarely isolated from extra-oro-intestinal abscesses. Reported here are four cases of extra-oro-intestinal abscesses due to polymicrobial flora, including Campylobacter species. The first case is a 35-year-old woman who was diagnosed with a brain abscess caused by C. gracilis, Streptococcus constellatus, and anaerobic Gram-positive cocci. The second case is a 65-year-old man with a history of maxillary sinus carcinoma who developed a brain abscess due to polymicrobial flora, including C. concisus. The third case is a 24-year-old male who was diagnosed with a vertebral abscess caused by C. rectus, Eubacterium brachy, and Actinomyces species. The fourth case is a 74-year-old woman who presented with an intraorbital abscess due to C. showae and Micromonas (previously Peptostreptococcus) micros. The first two patients died from a cause directly related to their abscesses. All Campylobacter species involved in the four cases were isolated anaerobically. The isolation of oral Campylobacter species, e.g., C. rectus and C. showae, from abscesses suggests an oral source. A survey of the English literature was undertaken to identify reports of Campylobacter species isolated from extra-oro-intestinal abscesses.

Bacteroides: the good, the bad, and the nitty-gritty

SUMMARY

Bacteroides species are significant clinical pathogens and are found in most anaerobic infections, with an associated mortality of more than 19%. The bacteria maintain a complex and generally beneficial relationship with the host when retained in the gut, but when they escape this environment they can cause significant pathology, including bacteremia and abscess formation in multiple body sites. Genomic and proteomic analyses have vastly added to our understanding of the manner in which Bacteroides species adapt to, and thrive in, the human gut. A few examples are (i) complex systems to sense and adapt to nutrient availability, (ii) multiple pump systems to expel toxic substances, and (iii) the ability to influence the host immune system so that it controls other (competing) pathogens. B. fragilis, which accounts for only 0.5% of the human colonic flora, is the most commonly isolated anaerobic pathogen due, in part, to its potent virulence factors. Species of the genus Bacteroides have the most antibiotic resistance mechanisms and the highest resistance rates of all anaerobic pathogens. Clinically, Bacteroides species have exhibited increasing resistance to many antibiotics, including cefoxitin, clindamycin, metronidazole, carbapenems, and fluoroquinolones (e.g., gatifloxacin, levofloxacin, and moxifloxacin).

A 16S rDNA-based nested PCR protocol to detect Campylobacter gracilis in oral infections

The aim of this study was to describe a 16S rDNA-based nested polymerase chain reaction (nPCR) assay to investigate the occurrence of Campylobacter gracilis in oral infections. Samples were collected from ten infected root canals, ten cases of acute periradicular abscesses and eight cases of adult marginal periodontitis. DNA extracted from the samples was initially amplified using universal 16S rDNA primers. A second round of amplification used the first PCR products to detect C. gracilis using oligonucleotide primers designed from species-specific 16S rDNA signature sequences. The nPCR assay used in this study showed a detection limit of 10 C. gracilis cells and no cross-reactivity was observed with nontarget bacteria. C. gracilis was detected in the three types of oral infections investigated - 4/10 infected root canals; 2/10 acute periradicular abscesses; and 1/8 subgingival specimens from adult periodontitis. The method proposed in this study showed both high sensitivity and high specificity to directly detect C. gracilis in samples from root canal infections, abscesses, and subgingival plaque. Our findings confirmed that C. gracilis may be a member of the microbiota associated with distinct oral infections, and its specific role in such diseases requires further clarification.

Campylobacter gracilis and Campylobacter rectus in primary endodontic infections

AIM

A species-specific nested polymerase chain reaction (PCR) assay was used to investigate the occurrence of Campylobacter gracilis and C. rectus in primary root canal infections.

METHODOLOGY

Samples were collected from 57 single-rooted teeth with carious lesions, necrotic pulps and radiographic evidence of periradicular disease. Twenty-eight cases were diagnosed as chronic asymptomatic periradicular lesions, 12 cases as acute apical periodontitis, and 17 cases as acute periradicular abscess. DNA was extracted from the samples and initially amplified using universal 16S rDNA primers. A second round of amplification using the first PCR products was performed to specifically detect C. gracilis or C. rectus in the samples.

RESULTS

Campylobacter gracilis and C. rectus were, respectively, detected in 21.4 (6 of 28) and 30% (6 of 20) of the root canals associated with chronic asymptomatic periradicular lesions. Campylobacter gracilis was found in 16.7% (2 of 12) of the cases diagnosed as acute apical periodontitis, whilst C. rectus was found in 33.3% (two of six cases). In the abscessed cases, C. gracilis and C. rectus were detected in 23.5 (4 of 17) and 11.8% (2 of 17) of the cases, respectively. No association of these species with clinical symptoms was observed (P > 0.01) In general, species-specific nPCR allowed the detection of C. gracilis in 21.1% (12 of 57) and C. rectus in 23.3% (10 of 43)of the samples taken from primary endodontic infections.

CONCLUSIONS

Findings confirmed the assertion that both C. gracilis and C. rectus participate in infections of endodontic origin and suggest a pathogenetic role with regard to periradicular diseases.

Association of early onset periodontitis microbiota with aspartate aminotransferase activity in gingival crevicular fluid

OBJECTIVES

The objective of this study was to determine the relationship between the activity of the enzyme aspartate aminotransferase (AST) in gingival crevicular fluid (GCF) using the colorimetric PerioGard (PTM) test and the subgingival microflora in early onset periodontitis lesions.

MATERIAL AND METHODS

The study population consisted of 25 otherwise healthy individuals exhibiting early onset periodontitis (EOP). In each patient four experimental sites were identified comprising one deep periodontal pocket (PD >5 mm) randomly chosen in each quadrant. Bacterial samples were obtained from the experimental sites, consecutively cultured anaerobically and in 10% CO(2) using selective and nonselective media. Isolates were characterized to species level by conventional biochemical tests and various identification kits. Clinical measurements as well as AST activity, assessed either as positive or negative using the PTM, were recorded at the same sites.

RESULTS

Sixty-two sites exhibited AST positive and 38 AST negative activity. Analysis of bacterial counts using the ANOVA (Mann Whitney U-test) showed that Streptococcus intermedius, Peptostreptococcus micros, Campylobacter concisus, Bacteroides forsythus, Camplobacter gracilis, Campylobacter rectus and Selenomonas sputigena were significantly higher in sites with AST-positive activity. The odds ratio of having high prevalence of S. intermedius, P. micros, C. concisus, B. forsythus, C. gracilis, C. rectus and S. sputigena in the presence of a positive AST site was very high (range: 3.5-17.0). Streptococcus sanguis, Actinomyces naeslundii, Gemella morbillorum, Capnocytophaga gingivalis, Veillonella parvula, Fusobacterium varium, Eubacterium lentum and Prevotella oralis were detected in significantly higher proportions in sites with AST negative activity and manifested a negative odds ratio in the presence of AST positive sites. The logistic regression analysis revealed that smoking and bleeding upon probing showed a significant association with AST activity, while plaque and suppuration were not found to be significant predictors of AST activity. The co-infection of Porphyromonas gingivalis, B. forsythus and P. micros, or P. gingivalis, B. forsythus and C. rectus were found to be significantly associated with the AST activity (p<0.001). AST positive sites revealed significantly higher occurrence of co-infections by P. gingivalis, B. forsythus, S. sputigena or by P. gingivalis, B. forsythus, S. intermedius than AST negative sites (p<0.001). P. gingivalis, B. forsythus, A. naeslundii co-infection was found significantly higher in the AST negative sites (p<0.001).

CONCLUSIONS

The present study found a high level of agreement between the presence of putative periodontal pathogens and positive AST scores at periodontal sites that clinically were considered to be potentially disease active. Prospective studies should be performed to confirm the findings.

The clinical and microbiological effects of systemic ornidazole in sites with and without subgingival debridement in early-onset periodontitis patients

BACKGROUND

The purpose of this study was to evaluate the clinical and microbiological effects of systemic ornidazole (ORN) in sites with or without subgingival debridement in early-onset periodontitis (EOP) patients.

METHODS

Two pooled bacterial samples consisting of 4 sites each (scaled and non-scaled sites) were obtained from 30 individuals exhibiting EOP. All patients received oral hygiene instruction (OHI), supragingival scaling and ORN. Subgingival scaling and root planing (SRP) was carried out only in scaled sites. Bacterial samples were taken at baseline (BL) and 1 week and 2, 6, and 12 months after systemic ornidazole administration (500 mg/bid for 7 days). One more sample was taken at scaled sites, one week after SRP.

RESULTS

One week following SRP (scaled sites) Gram-negative facultative and anaerobic rods were significantly reduced while Gram-positive facultative cocci were significantly increased. After ORN administration, P. gingivalis, P. denticola, P. intermedia, B. forsythus, C. rectus, and S. sputigena were no longer detectable in either scaled or non-scaled sites. A statistically significant long-term (2, 6, and 12 months) reduction of P. gingivalis, P. intermedia, P. loescheii, B. forsythus, and C. rectus and a pronounced increase of S. milleri, S. oralis, and S. sanguis counts in both scaled and non-scaled sites were detected in comparison to baseline. A sustained reduction of bleeding tendency and of probing depth was also observed in both scaled and non-scaled sites.

CONCLUSIONS

ORN combined with SRP effects beneficial shifts in the bacterial population associated with substantial clinical improvement, thereby indicating that ORN is effective adjunct in the treatment of EOP deep periodontal pockets where anaerobic bacteria are predominant.

Campylobacter species in health, gingivitis, and periodontitis

At least seven Campylobacter species have been identified from subgingival sites. Campylobacter rectus has been implicated as a periodontal pathogen; however, association with periodontal infections of other Campylobacter species, especially the newly described Campylobacter showae, is unclear. This study examined which Campylobacter species were associated with periodontal health and disease. Subgingival Campylobacter species from initial and established periodontitis were compared with species from periodontally healthy subjects, including subjects with gingivitis. Campylobacter species were isolated on selective media and identified by whole-cell protein profiles (SDS-PAGE). Except for C. rectus, Campylobacter levels were frequently below the detection limit (2-5% of the microbiota) of non-selective culture methods. C. rectus and C. showae, including Campylobacter X, were found more frequently and in higher levels from diseased than from healthy periodontal sites. C. gracilis was the dominant Campylobacter species found in relatively shallow pockets; however, its presence was unrelated to periodontal health or disease. C. concisus was isolated in higher proportions from relatively shallow and healthy sites, compared with deeper pockets. C. curvus was unrelated to periodontal health or disease. Analysis of the study data confirmed the relationship of C. rectus with diseased subgingival sites and indicated that C. showae may also be associated with periodontal disease.

Clinical and microbiological characteristics of smokers with early onset periodontitis

Cigarette smoking is a potential risk factor which has recently been associated with periodontal disease progression. The objective of this study was to compare the microbial profile of smokers and non-smokers in a group of patients with early onset periodontitis. The study population consisted of 60 healthy individuals, 40 males and 20 females aged 22 to 35 yr, exhibiting early onset periodontitis. Thirty patients were smokers (30.9 cigarettes/d) and 30 non-smokers. Smokers had a higher proportion of deep pockets (PD >5 mm), especially in the maxilla anterior and premolar regions (p < 0.001) and presented a significantly greater mean probing depth and attachment loss (p <0.05) in diseased sites and a significantly greater alveolar bone loss (p <0.01) compared to non-smokers. Two pooled bacterial samples were obtained from each patient. Samples were collected from the deepest periodontal pockets of each quadrant. The samples were cultured anaerobically and in 10% CO2 plus air for bacterial isolation using selective and non-selective media. Isolates were characterized to species level by conventional biochemical tests and various identification kits. Smokers harboured a greater number of bacteria in total. Analysis of bacterial counts using the ANOVA (Mann-Whitney U-test) showed that Staphylococcus aureus, Peptostreptococcus micros, Campylobacter concisus, Escherichia coli, Bacteroides forsythus, C. gracilis, C. rectus, Porphyromonas gingivalis, Selenomonas sputigena, Candida albicans and Aspergillus fumigatus were found in significantly higher numbers and more frequently in smokers while Streptococcus intermedius, A. naeslundii, A. israelii and Eubacterium lentum were detected more frequently and in significantly higher proportions in non-smokers. The isolation of bacteria belonging to the exogenous flora such as E. coli, C. albicans, A. fumigatus and S. aureus in smokers' microbiota underscores the importance of the host that is adversely affected by cigarette smoking.

Clinical relevance of antimicrobial susceptibility testing

In recent years, significant resistance to antimicrobial agents has been encountered among certain anaerobic bacteria. Susceptibility patterns vary from region to region, but even within a given region susceptibility is not always predictable. Initially, therapy of mixed anaerobic infections must be empirical, based on the nature of the infection, the usual flora of such infections, anticipated modification of this flora by pathophysiologic processes or prior antimicrobial therapy, and evaluation of Gram stains from appropriate specimens. If the infection does not respond well or the patient requires long-term therapy, antimicrobial susceptibility testing may be indicated in order to provide optimum therapy. Susceptibility testing is also indicated for determination of the usual patterns in a particular hospital, for monitoring geographical patterns, and to determine the activity of new antimicrobial agents.

The early colonization of gram-negative anaerobic bacteria in edentulous infants

The occurrence of oral gram-negative anaerobes was examined in 30 edentulous infants (mean age 3 months, range 1-7 months). One pooled swab sample from mucosal surfaces (cheeks, palate, tongue) and one saliva sample was taken from each infant. The samples were cultured aerobically and anaerobically using non-selective and selective media. Prevotella (Bacteroides) melaninogenica was the most frequently isolated anaerobe, found in 70% of the infants. The other common anaerobes were Fusobacterium nucleatum, Veillonella spp. and nonpigmented Prevotella (Bacteroides) spp., found in 60%, 57% and 57% of the infants, respectively. Of corroding bacilli, Bacteroides gracilis was detected in 23% of the infants, Wolinella spp. and microaerophilic Eikenella corrodens in one infant (3% each). Leptotrichia spp., microaerophilic Capnocytophaga spp., Prevotella (Bacteroides) loescheii and Prevotella (Bacteroides) intermedia were found in 17%, 13%, 13% and 7% of the infants, respectively. In addition to these 30 infants, 21 edentulous infants were investigated for the presence of Actinobacillus actinomycetemcomitans only. A. actinomycetemcomitans was not detected in any of the 51 edentulous infants. The number of different anaerobic bacterial species in the same mouth varied from 0 to 7. No anaerobic bacteria were detected in 3 of 30 children (10%). These data suggest that various anaerobic bacterial species readily colonize the edentulous mouth in infants.

Comparative in vitro activity of cefpodoxime against anaerobes other than Bacteroides fragilis

To assess the in vitro activity of cefpodoxime against anaerobic respiratory tract and oropharyngeal pathogens 77 strains belonging to 18 gram-negative and 7 gram-positive species were studied by means of agar dilution tests. For comparison cefuroxime, amoxicillin, amoxicillin + clavulanic acid and clindamycin were also tested. Cefpodoxime was found to be active at concentrations of less than or equal to 0.125 mg/l against Prevotella oralis, Prevotella buccalis, Prevotella bivia, Porphyromonas asaccharolytica, Bacteroides corporis, Bacteroides gracilis, Fusobacterium necrophorum, Fusobacterium naviforme and Propionibacterium acnes. Prevotella oris, Prevotella buccae, Fusobacterium nucleatum, Peptostreptococcus asaccharolyticus, and Ruminococcus bromii were inhibited at concentrations of less than or equal to 1 mg/l and Prevotella denticola, Prevotella melaninogenica, Prevotella intermedia, Porphyromonas gingivalis, Bacteroides pneumosintes, and Peptostreptococcus micros at concentrations of less than or equal to 4 mg/l. Strains of Veillonella parvula were inhibited by cefpodoxime at 0.25-8 mg/l, and single strains of Peptostreptococcus anaerobius and Peptostreptococcus magnus showed MICs of 32 and 64 mg/l, respectively. The results obtained warrant the use of cefpodoxime in therapy of anaerobic and mixed aerobic-anaerobic infections of the upper and lower respiratory tract and similar infections not involving Bacteroides fragilis.

Atypical structure of the 23S ribosomal RNA molecule in certain oral bacteria

Ribosomal RNA (rRNA) isolated from Wolinella recta and seven related bacteria was examined by agarose gel electrophoresis. The 23S rRNA molecule could not be detected in W. recta, Wolinella curva, Bacteroides gracilis, or Bacteroides ureolyticus. In place of the 23S molecule, there were three smaller molecules of approximately 1700, 650, and 600 bases designated 23S alpha, 23S beta, and 23S delta, respectively. An intact 23S rRNA molecule could be isolated from Wolinella succinogenes, Campylobacter concisus, and Campylobacter sputorum. The cleavage sites of the W. recta 23S rRNA molecule were located by direct RNA sequence analysis and were found to be in similar locations, nucleotides 546 and 1180, as cleavage sites described in other prokaryotes. The presence or absence of the 23S rRNA molecule may be a useful marker for these micro-organisms.

Effect of beta-lactamase inhibitors on the activities of various beta-lactam agents against anaerobic bacteria

The in vitro activities of several new beta-lactam-beta-lactamase inhibitor combinations (piperacillin plus tazobactam, ceftizoxime and cefonicid with sulbactam and clavulanic acid, and ampicillin plus 8 micrograms of sulbactam per ml) were tested with anaerobic bacteria and compared with known beta-lactam-beta-lactamase inhibitor combinations and other potent antianaerobe agents. All the combinations tested (except for the cefonicid-inhibitor combinations) were active against almost all strains of the Bacteroides fragilis group. This report indicates that beta-lactamase inhibitors may improve the activity of beta-lactam agents with marginal activity against the B. fragilis group.

Multivariate analyses of cellular fatty acids in Bacteroides, Prevotella, Porphyromonas, Wolinella, and Campylobacter spp

The genera Bacteroides, Wolinella, and Campylobacter contain several similar species that require taxonomic revision. Fatty acid profiles of whole bacterial cells have proven useful for taxonomy. In this study, cellular fatty acids from Bacteroides, Prevotella, Porphyromonas, Wolinella, and Campylobacter spp. were identified and quantitated by gas chromatography and gas chromatography-mass spectrometry, and the data were subjected to principal component analyses. Bacteroides fragilis, the type species of the genus Bacteroides, was distinct from the other organisms. While Bacteroides gracilis, Wolinella succinogenes, Wolinella curva, Wolinella recta, and Campylobacter fetus subsp. venerealis were close to each other, Prevotella (Bacteroides) buccae, Prevotella oralis, Prevotella oris, Prevotella disiens, Prevotella veroralis, Prevotella heparinolyticus, Porphyromonas (Bacteroides) endodontalis, and Bacteroides ureolyticus could be distinguished. B. fragilis was characterized by the presence of C3OH-i-1-, Ca-15, and Ci-15 and the absence of C12:0 and unsaturated fatty acids. For comparison, B. gracilis, B. ureolyticus, W. succinogenes, W. curva, W. recta, and Campylobacter fetus subsp. venerealis contained C12:0, C16:1, C18:1, and C3-OH-14 acids but lacked branched hydroxy and branched nonhydroxy acids. B. gracilis and B. ureolyticus are not "true" bacteroides.

Selective medium for isolation of Bacteroides gracilis

A new medium selective for Bacteroides gracilis was developed. The medium is tryptic soy agar (Difco Laboratories, Detroit, Mich.) containing nalidixic acid, teicoplanin, sodium formate, sodium fumarate, and potassium nitrate. All 18 strains of B. gracilis tested grew with only minimal inhibition. Most of the other 214 organisms tested, including most Bacteroides species, other anaerobes, and a substantial number of facultative anaerobes, were significantly inhibited by the medium. In a diagnostic study of 49 clinical specimens (28 patients with intra-abdominal infection, mostly gangrenous or perforated appendicitis), four strains of B. gracilis were isolated (from 4 different patients) on B. gracilis selective agar but were not detected on standard media.

Newly delineated periodontal pathogens with special reference to selenomonas species

Many new species have been isolated from subgingival periodontal pockets, for example Wolinella recta and Bacteroides forsythus, reflecting better basic microbiological techniques. Other species were created from existing species as a result of better characterization methods, i.e. Bacteroides buccae and Bacteroides oris. We can recognize different types of periodontal disease and can find differences relating to the progressive compared to inactive lesions. Data illustrated in this presentation suggest that potential pathogens within new species include B. forsythus, W. recta and quite probably Selenomonas noxia. Methods that are rapid and sensitive for these new species include the use of protein profiles determined using SDS-PAGE, and DNA probes.

National Committee for Clinical Laboratory Standards agar dilution susceptibility testing of anaerobic gram-negative bacteria

One hundred nine recent clinical isolates of anaerobic gram-negative bacteria were tested in triplicate by the National Committee for Clinical Laboratory Standards agar dilution procedure for their susceptibility to 32 antimicrobial agents. All isolates were inhibited by imipenem, but there were significant numbers of strains resistant to other beta-lactam drugs, and therefore the in vitro response to these antimicrobial agents cannot be predicted. This was particularly true for the bile-resistant or Bacteroides fragilis group. beta-Lactamase production was detected in 82% of the bacteroides with the nitrocefin test. Clavulanic acid combined with amoxicillin and ticarcillin and sulbactam combined with ampicillin resulted in synergistic activity against all beta-lactamase-positive organisms. Ceftizoxime was the most active of the cephalosporins. Two percent of the isolates were resistant to chloramphenicol and metronidazole. Clindamycin resistance was detected in 38% of the B. fragilis group, which is a marked increase from the 4% detected 10 years ago at this institution.

In vitro activity of cefoperazone plus sulbactam compared with that of other antimicrobial agents against anaerobic bacteria

The activity of two cefoperazone-sulbactam combinations against anaerobic bacteria was tested and compared both with that of cefoperazone alone and with that of other commonly used antimicrobial agents. Imipenem was the most active of the tested agents, followed by chloramphenicol, metronidazole, and cefoperazone-sulbactam (90 to 100% of bacterial growth inhibited). Clindamycin and cefoxitin inhibited approximately 80%, cefoperazone inhibited 63%, and penicillin G inhibited 47% of the strains tested. The agents were variable in activity against the Bacteroides fragilis group, with percents susceptible as follows: cefoperazone-sulbactam, imipenem, metronidazole, and chloramphenicol, 99 to 100%; cefoxitin and clindamycin, approximately 80%; cefoperazone, 49%; and penicillin G, 15.5%.

Characterization of Wolinella spp., Campylobacter concisus, Bacteroides gracilis, and Eikenella corrodens by polyacrylamide gel electrophoresis

The small asaccharolytic, nonpigmenting gram-negative rods of the human oral cavity are difficult to differentiate from each other. Protein profiles of sonicated cells of Wolinella species, Campylobacter concisus, Bacteroides gracilis, and Eikenella corrodens were obtained by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and visualized with a silver stain. The gels were scanned with a laser densitometer, and the similarity of strains was computed by determining correlation coefficients of normalized densities along the gels. The strains were grouped by cluster analysis of the correlation coefficients. All species were distinct from each other. Several groups were found within E. corrodens. A colored silver stain was found to highlight species differences and appears to be useful in the rapid identification of fresh isolates.