Actinobacillus actinomycetemcomitans pneumonia with chest wall involvement and rib destruction

Aggregatibacter actinomycetemcomitans infection in a 15-year-old boy with pulmonary empyema: a case report and review of literature

BACKGROUND

Aggregatibacter actinomycetemcomitans (Aa), previously known as Actinobacillus actinomycetemcomitans, is a slow-growing Gram-negative coccobacillus, member of the HACEK group of bacteria colonizing oral flora. Besides causing infectious diseases in the oral cavity such as dental caries and periodontitis, it is responsible for severe extra-oral infections secondary to hematogenous spread or aspiration, such as endocarditis, soft tissue abscesses and osteomyelitis. The diagnosis depends on prolonged bacterial culture of biological material obtained through biopsy. Aa is susceptible to most antibiotics but complete eradication often requires a long term treatment.

CASE PRESENTATION

We report the case of a 15-year-old previously healthy boy diagnosed with both pulmonary empyema and subphrenic chest wall abscess caused by Aa. He was admitted to our Pediatric Emergency department for evaluation of a right mass associated with marked asthenia and dry cough. After radiological findings etiological diagnosis was made by culture of fluid drainage of pleural empyema. He started empirical antibiotic therapy with intravenous piperacillin/tazobactam, whose sensibility was confirmed by the antibiogram, then, for occurrance of hepatopathy it was switched to ciprofloxacin: the patient almost completely recovered after 6-month therapy.

CONCLUSIONS

Extra-oral infections caused by Aa are extremely rare, especially in children, and not well described yet. To our knowledge, there is only another similar case described in literature. However, the case described in our manuscript represents the only one presenting with pulmonary empyema without involvement of lung parenchyma in children. We also conducted a brief review of published cases of Aa infection in the pediatric population. This case report reminds us the importance of an accurate inspection of the oral cavity during the examination of pediatric patients.

Infective endocarditis by HACEK: a review

Infective endocarditis (IE) is a severe disease that is still associated with high mortality despite recent advances in diagnosis and treatment. HACEK organisms (Haemophilus spp., Aggregatibacter actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae) are gram-negative bacteria that are part of the normal flora of the mouth and upper respiratory tract in humans. These organisms cause a wide range of infections, of which IE is one of the most notable. In order to control and prevent endocarditis caused by HACEK, measures such as oral hygiene and the use of prophylactic drugs should be used for people at risk, including people with underlying heart disease and people with artificial valves. This review is a summary of the main aspects of IE focusing on HACEK organisms.

The role of oral microbiome in respiratory health and diseases

The oral cavity (mouth) has various microbial habitats, including, teeth, gingival sulcus, gingiva, tongue, inner cheek, hard palate, and soft palate. The human oral cavity houses the second most diverse microbiome in the body harboring over 700 bacterial species. The fine-tuned equilibrium of the oral microbiome ecosystem maintains oral health. Oral dysbiosis caused by food habits and poor oral hygiene leads to various oral diseases such as periodontitis, caries, gingivitis, and oral cancer. Recent advances in technology have revealed the correlation between the oral microbiome and systemic diseases such as pulmonary diseases, cardiovascular diseases, rheumatoid arthritis, Alzheimer's disease, and other metabolic diseases. Since the oral cavity directly connects with the upper respiratory tract, the oral microbiome has easier access to the respiratory system compared to other organ systems. Direct aspiration of oral microflora in the respiratory system and oral dysbiosis-induced host immune reaction and inflammation are mainly responsible for various pulmonary complications. Numbers of literature have reported the correlation between oral diseases and pulmonary diseases, suggesting the possible role of the oral microbiome in respiratory diseases such as chronic obstructive pulmonary diseases, pneumonia, lung cancer, etc. This paper reviews the current evidence in establishing a link between the oral microbiome and pulmonary diseases. We also discuss future research directions focusing on the oral microbiome to unravel novel therapeutic approaches that could prevent or treat the various pulmonary complications.

Pulmonary Aggregatibacter actinomycetemcomitans infection masquerades as malignancy in a patient with periodontitis

A 49-year-old man with a 37.5 pack-year smoking history presented with a suspected neoplasm of the right lung following the discovery of a metabolically active mass on positron emission tomography-CT imaging. The patient, who demonstrated poor oral hygiene, had a history of irregular problem-oriented dental visitation. Having excluded malignancy through histologic investigations, Aggregatibacter actinomycetemcomitans-a well-established periodontal pathogen-was subsequently cultured from his pulmonary aspirate. The patient was therefore managed with systemic antimicrobials and adjunctive dental extractions to eliminate the likely source of infection, whereafter the mass resolved without complication. This case corroborates previous reports of extraoral isolation of A. actinomycetemcomitans, which may mimic cancer clinically and radiographically. While a definitive causative link between untreated periodontitis and systemic infection remains to be elucidated, such cases present a compelling argument in favour of promoting oral health to prevent systemic disease.

Orale Immunkompetenz in der Corona-Pandemie vs. Systemrelevanz der Zahnmedizin

Die Covid-19-Pandemie hat das deutsche Gesundheitssystem im Jahr 2020 vor erhebliche Herausforderungen gestellt. In diesem Zusammenhang ist es bemerkenswert, dass für die Zahnmedizin kein sogenannter Rettungsschirm aufgespannt wurde. Dies bedeutet, dass nach Ansicht der Bundesregierung Zahnärzte als nicht systemrelevant eingestuft wurden und somit offiziell auch nicht zu den Ärzten gehören. Diese Annahme ist grundfalsch und gefährlich, wie im Folgenden anhand eines wichtigen Beispiels erörtert wird.

Das SARS-CoV-2-Virus führt bei infizierten Personen zu einem Beschwerdebild von leichten Erkältungszeichen bis hin zu lebensbedrohlichen beatmungsbedürftigen COVID-19-Pneumonien. Ein besonderes Risiko für schwere Verläufe haben Menschen höheren Alters sowie Patienten mit Diabetes, Bluthochdruck und anderen schweren Erkrankungen. Die Haupteintrittspforte für das SARS-CoV-2-Virus in den menschlichen Körper ist u. a. die orale Mukosa, denn die Viren reichern sich dort bevorzugt an und der ACE2-Rezeptor wird dort hochgradig exprimiert. Dieser Penetrationsweg erklärt die häufigeren schweren Verläufe bei älteren Diabetespatienten, deren Immunsystem bereits generell beeinträchtigt ist. Diabetes mellitus induziert eine chronische systemische Entzündung, die sich gerade im Mundbereich regelmäßig als Parodontitis manifestiert. Bei Diabetikern zwangsläufig oft auftretende Hyperglykämien schwächen die Mukosa-Barriere zusätzlich. Es ist daher dringend ratsam, bei Präventionsmaßnahmen für Diabetespatienten den Mund- und Rachenraum nicht zu ignorieren. Neben der parodontalprophylaktischen Betreuung ist gerade in Absenz von Zahnärzten die aktivierte Matrix-Metalloproteinase 8 (aMMP8) ein etablierter Biomarker. Die aktuellen Empfehlungen zur Prävention der SARS-CoV-2-assoziierten COVID-19-Erkrankung sollte daher um die Aspekte der Messung und Sanierung des Mund- und Rachenraums sowie einer regelmäßigen Desinfektion der oralen Mukosa erweitert werden.

Aggregatibacter actinomycetemcomitans Causing Empyema Necessitans and Pyomyositis in an Immunocompetent Patient

Empyema necessitans is a relatively rare clinical entity in which the empyema extends through the parietal pleura into the adjacent soft tissue and musculature of the chest wall. It usually occurs due to inadequate treatment of a primary lung infection. Aggregatibacter (formerly Actinobacillus) actinomycetemcomitans is a facultative anaerobic gram-negative coccobacillus that is part of the normal oral flora. Infections due to this organism usually result from aspiration in conjunction with dental disease or trauma to the oral mucosa resulting in pneumonia or empyema. It often coinfects with Actinomyces and is known to cause empyema necessitans. Cases of monomicrobial empyema necessitans due to Aggregatibacter actinomycetemcomitans in adults have rarely been reported with four such publications found on review of the literature. We present a patient with severe periodontitis who developed empyema necessitans due to Aggregatibacter actinomycetemcomitans likely from aspiration complicated by pyomyositis of the right triceps brachii and a left posterior thigh abscess.

Relationship between periodontal disease and lung cancer: A systematic review and meta-analysis

Periodontal disease (PD), as a chronic bacterial infection, might cause cardiovascular and some other systemic diseases, with recent studies reporting that it exhibits some connection with lung cancer. While studies have shown that poor oral health might increase the risk of lung cancer, the veracity of these reports is questionable. Therefore, this meta-analysis was undertaken to investigate the association between PD and the risk of lung cancer. A search was run in PubMed, EMBASE, MEDLINE, CENTRAL, and ClinicalTrials.gov databases up to January 1, 2020. Cohort and case-control studies investigating the correlation between PD and lung cancer were included. Eligibility assessment and data extraction were conducted independently, and a meta-analysis was performed to synthesize the data. The association between PD, edentulism, and lung cancer was measured by the adjusted hazard ratios (HRs) or odds ratios (ORs) and their 95% confidence intervals (CIs) provided in articles. We employed appropriate effect model in terms of I² (a fixed-effect model for PD and a random-effect model for edentulism) to obtain summary effect estimates. Statistical heterogeneity was investigated by chi-square test and I² statistics. Newcastle-Ottawa Scale (NOS) was used to assess the quality of their method. Six cohort studies (eight references) and two case-control studies, assessed as high-quality, involving 167 256 participants, were included in the review. The summary estimates based on adjusted data showed an association between PD and a significant risk of lung cancer both in cohort studies (HR = 1.40, 95% CI = 1.25-1.58; I²  = 8.7%) and case-control studies (OR = 1.51, 95% CI = 1.16-1.98; I²  = 36.5%). Similar features were found in the sensitivity analysis and subgroups for six cohort studies, of male only (HR = 1.36, 95% CI = 1.15-2.60), setting the lung cancer incidence as endpoint (HR = 1.39, 95% CI = 1.24-1.57; I²  = 23.9%), and adjusting alcohol for multifactorial HR (HR = 1.38, 95% CI = 1.21-1.57; I²  = 39.9%). The summary HR for edentulism was 1.93 (95% CI = 1.05-3.57; I²  = 55.3%). No obvious publication bias was detected. This systematic review and meta-analysis demonstrated a significant association between PD and the incidence of lung cancer. Further observational studies are required by using standardized measurements to assess the periodontal status and by eliminating confounding factors, such as alcohol and diabetes, to verify such a relationship.

Diaphragmatic mass caused by Aggregatibacter actinomycetemcomitams

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actinomycetemcomitans causes periodontitis, endocarditis and soft tissue abscess.

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First case of A. actinomycetemcomitans diaphragmatic infection without lung injury.

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Hematogenous spread of A. actinomycetemcomitans from oral mucosa to thorax.

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Color is not necessary for the figure.

A 52-year-old man was evaluated in our outpatient facility because of a thoracic mass for one month. A needle biopsy of the chest mass was performed and microbiological culture showed growth of Aggregatibacter actinomycetemcomitans. Three months after starting antimicrobial therapy, acute phase reactants normalized, and chest CT showed a progressive reduction in the size of the phlegmon. To our knowledge, we report the first case of A. actinomycetemcomitans diaphragmatic and chest wall infection without pulmonary involvement. This supports the theory of hematogenous spread of the germ from oral mucosa to produce thoracic lesions.

Mixed Actinomyces israelii and Aggregatibacter actinomycetemcomitans infection causing empyema necessitatis and multiple skin abscesses in an immunocompetent patient

A 45-year-old- man presented with left chest wall pain, swelling and cough. Over a 2-month period he developed abscesses in the right foot, right anterior thigh, left buttock and left chest. Incision and drainage of the soft tissue abscesses and video-assisted thoracoscopic surgery to drain the loculated empyema contiguous with the chest wall abscess were performed as surgical management. Gram stain showed beaded Gram-positive rods and the culture initially grew Aggregatibacter actinomycetemcomitans and Eikenella corrodens Pathological evaluation of the pleura showed sulfur granules and organisms consistent with Actinomyces spp. on Gomori methenamine silver stain; Actinomyces israelii was recovered in culture with extended incubation. The patient was treated for 3 weeks with ceftriaxone and oral metronidazole, followed by oral amoxicillin. Culture of A. actinomycetemcomitans with other findings consistent with actinomycosis warrants 6-12 months of antibiotic therapy.

Aggregatibacter actinomycetemcomitans pneumonia with chest and abdominal wall involvement

A 54-year-old man presented with a productive cough, chest pain, fever and weight loss. Initial analysis revealed a palpable chest wall mass and consolidation in the left lower lobe and pleural abnormalities on imaging. At that point no infectious cause or malignancy was identified. Microbiological analysis of a needle biopsy from a newly developed abdominal wall mass revealed growth of Aggregatibacter actinomycetemcomitans The patient was successfully treated with antibiotic therapy for 1 year. Aggregatibacter actinomycetemcomitans is a Gram-negative coccobacillus and is part of the normal oral flora. It is capable of causing infections in humans including periodontitis, soft tissue abscesses and systemic invasive infections, most commonly endocarditis.

From focal sepsis to periodontal medicine: a century of exploring the role of the oral microbiome in systemic disease

The oral microbiome is established within a few minutes after birth and consists of stable multi-species communities that engage in a dynamic equilibrium with the host immune system. Dental caries, endodontic infections and periodontal diseases are bacterially driven diseases that are caused by dysbiotic microbiomes. Over a century ago, the focal infection theory implicated these infections in the aetiology of several systemic diseases, ranging from arthritis to neurodegenerative diseases. However, a lack of concrete evidence, combined with the urgency with which clinicians embraced this approach without regard for appropriate case selection, led to its demise within 30 years. In the last decade of the 20th century, the concept of periodontal medicine was introduced to explain the correlations that were being observed between periodontitis and cardiovascular disease, rheumatoid arthritis, Alzheimer's disease, pulmonary disease, pre-term delivery of low birth weight infants and metabolic disease. It was proposed that periodontal pathobionts played a causal role in the initiating or exacerbating certain diseases either by direct invasion or by stimulating a florid immune-inflammatory response that extended into the systemic circulation. This review will examine the strength of current evidence in establishing a causal link between oral pathobionts and systemic disease.

Linkages between oral commensal bacteria and atherosclerotic plaques in coronary artery disease patients

Coronary artery disease is an inflammatory disorder characterized by narrowing of coronary arteries due to atherosclerotic plaque formation. To date, the accumulated epidemiological evidence supports an association between oral bacterial diseases and coronary artery disease, but has failed to prove a causal link between the two. Due to the recent surge in microbial identification and analyses techniques, a number of bacteria have been independently found in atherosclerotic plaque samples from coronary artery disease patients. In this study, we present meta-analysis from published studies that have independently investigated the presence of bacteria within atherosclerotic plaque samples in coronary artery disease patients. Data were collated from 63 studies covering 1791 patients spread over a decade. Our analysis confirms the presence of 23 oral commensal bacteria, either individually or in co-existence, within atherosclerotic plaques in patients undergoing carotid endarterectomy, catheter-based atherectomy, or similar procedures. Of these 23 bacteria, 5 (Campylobacter rectus, Porphyromonas gingivalis, Porphyromonas endodontalis, Prevotella intermedia, Prevotella nigrescens) are unique to coronary plaques, while the other 18 are additionally present in non-cardiac organs, and associate with over 30 non-cardiac disorders. We have cataloged the wide spectrum of proteins secreted by above atherosclerotic plaque-associated bacteria, and discuss their possible roles during microbial migration via the bloodstream. We also highlight the prevalence of specific poly-microbial communities within atherosclerotic plaques. This work provides a resource whose immediate implication is the necessity to systematically catalog landscapes of atherosclerotic plaque-associated oral commensal bacteria in human patient populations.

A review of bacterial populations in the mouth and in diseased arteries will help research into the role of bacteria in heart disease. Amit Sharma and colleagues at the International Centre for Genetic Engineering and Biotechnology, with co-workers at the All India Institute of Medical Sciences, both in New Delhi, India, analyzed 63 studies covering 1791 patients spread over a decade. They summarize evidence of 23 types of oral bacteria that are also found in atherosclerotic plaques in artery walls. The review also cataloged the proteins secreted by the bacteria and discussed possible involvement of these proteins in the migration of bacteria through the bloodstream. Full genetic details are available for 19 of the 23 bacterial species, which should greatly assist further investigations into the significance of bacteria in the onset of heart disease.

Oral microbiota and systemic disease

It is well known that bacteria are the primary cause of infectious diseases, however, evidence is emerging that these organisms are also indirectly responsible for several diseases including cancer and rheumatoid arthritis. The oral cavity is home to several million bacteria that can cause two major diseases-periodontitis and caries. The relationship between periodontopathic bacteria and systemic diseases has been explored for several years. The concept of the oral cavity as a source of distant infection has been debated for at least a century. This review will discuss the historic aspects of the development of the focal infection theory, the reasons for its demise, its re-emergence and current status.

Probing bacterial metabolism during infection using high-resolution transcriptomics

A fundamental aspect of most infectious diseases is the need for the invading microbe to proliferate in the host. However, little is known about the metabolic pathways required for pathogenic microbes to colonize and persist in their hosts. In this study, we used RNA sequencing (RNA-seq) to generate a high-resolution transcriptome of the opportunistic pathogen Aggregatibacter actinomycetemcomitans in vivo. We identified 691 A. actinomycetemcomitans transcriptional start sites and 210 noncoding RNAs during growth in vivo and as a biofilm in vitro. Compared to in vitro biofilm growth on a defined medium, ∼14% of the A. actinomycetemcomitans genes were differentially regulated in vivo. A disproportionate number of genes coding for proteins involved in metabolic pathways were differentially regulated in vivo, suggesting that A. actinomycetemcomitans in vivo metabolism is distinct from in vitro growth. Mutational analyses of differentially regulated genes revealed that formate dehydrogenase H and fumarate reductase are important A. actinomycetemcomitans fitness determinants in vivo. These results not only provide a high-resolution genomic analysis of a bacterial pathogen during in vivo growth but also provide new insight into metabolic pathways required for A. actinomycetemcomitans in vivo fitness.

A comparison of Aggregatibacter actinomycetemcomitans (Aa) virulence traits in a rat model for periodontal disease

Our aim was to explore the effects of Cytolethal Distending toxin (Cdt) in a well established rat model of periodontal disease where leukotoxin (LtxA) was thought to have no known effect. In vitro studies, were used to assess CdtB activity using Aa Leukotoxin as a negative control. These studies showed that both CdtB and LtxA (unexpectedly) exerted significant effects on CD4⁺ T cells. As a result we decided to compare the effects of these two prominent Aa virulence factors on bone loss using our rat model of Aa-induced periodontitis. In this model, Aa strains, mutant in cdtB and ltxA, were compared to their parent non-mutant strains and evaluated for colonization, antibody response to Aa, bone loss and disease. We found that bone loss/disease caused by the ltxA mutant strain, in which cdtB was expressed, was significantly less (p<0.05) than that due to the wild type strain. On the other hand, the disease caused by cdtB mutant strain, in which ltxA was expressed, was not significantly different from the wild type strain. This data indicates that Aa LtxA exerts a greater effect on bone loss than Cdt in this rat model of periodontal disease and supports the utility of this model to dissect specific virulence factors as they relate to immunopathology in studies of Aa-induced disease.

Brain abscess associated with Aggregatibacter actinomycetemcomitans: case report and review of literature

INTRODUCTION

Aggregatibacter actinomycetemcomitans is considered a major pathogen in localized and generalized aggressive periodontitis. A. actinomycetemcomitans has been found in various extra oral infections and most frequently in endocarditis. We report a patient with multiple brain abscesses due to infection with A. actinomycetemcomitans and review the English language literature related to this subject.

CASE REPORT

A 42-year-old patient with no underlying medical conditions presented with multiple brain lesions initially thought to be metastatic lesions of a tumour of unknown origin. Findings during drainage and subsequent histopathological conclusions made infection more likely. Culture of drained material remained negative; however, 16S rDNA polymerase chain reaction and sequence analysis on direct material revealed A. actinomycetemcomitans as the causative agent of the infection. The most likely source of infection was the poor dentition of the patient. After repeated drainage of the lesions and antibiotic treatment the patient gradually improved, although cognitive impairment remained.

CONCLUSIONS

Our report illustrates that a poor dental condition, notably destructive periodontal disease, can be a risk for life-threatening extra oral disease, and thus contributes to the total inflammatory burden of the body.

Invasive infections of Aggregatibacter (Actinobacillus) actinomycetemcomitans

BACKGROUND/PURPOSE

Aggregatibacter (Actinobacillus) actinomycetemcomitans, part of the normal flora of the mouth, is frequently found in human periodontal cultures and is an important pathogen causing various invasive infections, particularly infective endocarditis. In this study, we describe the clinical course and outcome of patients with A. actinomycetemcomitans infection.

METHODS

All patients suffering invasive A. actinomycetemcomitans infections at the National Taiwan University Hospital from January 1985 to December 2004 were included in this study. Relevant data regarding clinical presentation, antimicrobial treatment and outcome of these patients were analyzed.

RESULTS

During the study period, there were 11 patients with invasive A. actinomycetemcomitans infections, including eight patients with infective endocarditis, one with osteonecrosis and two with pneumonia and chest wall lesions. Among the patients with infective endocarditis, four had prosthetic valve replacement, four suffered from rheumatic heart disease and one had undergone surgical repair of ventricular septal defect. Lesions in the oral cavity were the probable portals of entry of the microorganism, and included carious teeth, periodontitis or radiotherapy of the ear-nose-throat field, and were noted in nine patients. Transthoracic echocardiography and/or transesophageal echocardiography were performed on the patients with probable infective endocarditis but growth was demonstrated in only four of these patients. Blood culture yielded A. actinomycetemcomitans after prolonged incubation. Three isolates were resistant to penicillin and two of these were also resistant to ampicillin.

CONCLUSION

The diagnosis of invasive A. actinomycetemcomitans infection was delayed due to the indolent clinical course, non-specific presentation and slow growth of the organism. Antibiotic therapy using amoxicillin/clavulanic acid, ampicillin, ampicillin/sulbactam, ceftriaxone, clindamycin, cefotaxime, or levofloxacin was successful in all patients. None of the patients demonstrated recurrence of infection 2-36 months following treatment.

Aggregatibacter actinomycetemcomitans-induced bone loss and antibody response in three rat strains

BACKGROUND

The aim of this study is to compare the colonization, immunoglobulin (Ig) G response, and alveolar bone loss in Aggregatibacter actinomycetemcomitans (Aa)-inoculated Fawn Hooded Hypertensive (FHH), Dahl Salt-Sensitive (DSS), and Brown Norway (BN) rats.

METHODS

Each rat strain was divided into wild-type Aa-inoculated and non-inoculated control groups. Blood taken at 12 weeks after inoculation was assessed for Aa-specific IgG antibodies by an enzyme-linked immunosorbent assay. Colonization was assessed 12 weeks postinoculation. Bone loss was estimated by measuring the distance from the cemento-enamel junction (CEJ) to the alveolar bone crest (ABC) at 20 molar sites. Colonization and antibody levels were compared by using the Student t test. Diseased rats were defined as having two sites per quadrant with CEJ-ABC distances that were significantly greater than the control CEJ-ABC distances.

RESULTS

The Aa colonization of FHH rats was significantly higher than in other strains (P <0.05). The Aa-specific IgG levels in the DSS Aa-inoculated group were significantly higher than in its control group (P <0.05). Only FHH rats showed Aa disease-associated bone loss (P = 0.0021).

CONCLUSIONS

Aa colonized and caused more disease in FHH rats than in the other rat strains. The rat strains each responded differently to the same Aa strain.

High incidence of actinobacillus actinomycetemcomitans infection in acute coronary syndrome

Recent epidemiological studies suggest that periodontitis is an important risk factor for coronary heart disease (CHD). The aim of this study was to evaluate the association between periodontitis and CHD, particularly acute coronary syndrome (ACS), focusing on microbiological and immunological features. Twenty-eight CHD patients, 15 with ACS and 13 with chronic CHD, were included in this study. Coronary angiography, periodontal examination, and dental radiography were performed in all patients. Subgingival plaque, saliva, and blood samples were analyzed for the periodontopathogens Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythensis, Treponema denticola, and Prevotella intermedia using polymerase chain reaction. Specific serum antibody titers to the 5 periodontal pathogens were determined by enzyme-linked immunosorbent assay. It was found that 33% of the ACS patients (5/15) harbored A. actinomycetemcomitans in oral samples, whereas no A. actinomycetemcomitans (0/13) was found in the chronic CHD patients (P < 0.05). Furthermore, ACS patients showed significantly higher serum IgG titers to A. actinomycetemcomitans (P < 0.05) compared with chronic CHD. More tooth loss and alveolar bone loss were noted in ACS patients than in chronic CHD patients, although the differences were not statistically significant. Periodontal pathogens, particularly A. actinomycetemcomitans, may play a role in the development of ACS.

Detection of Actinobacillus actinomycetemcomitans but not bacteria of the red complex in aortic aneurysms by multiplex polymerase chain reaction

BACKGROUND

Aortic aneurysms affect an increasing number of elderly patients and cause considerable morbidity and mortality. The understanding of the mechanisms involved in the pathogenesis of aortic aneurysms is unclear and little is known about the role of microorganisms in the development of the condition. The aim of the present study was to examine aortic aneurysm samples for the presence of four putative periodontal pathogens: Actinobacillus actinomycetemcomitans, Treponema denticola, Tannerella forsythensis, and Porphyromonas gingivalis.

METHODS

Fifty-six samples from the aneurysm wall were obtained from patients undergoing aneurysm repair. DNA was extracted from tissue by conventional methods. Universal eubacterial primers for general detection of bacteria and species specific primers for detection of the periodontal pathogens were used to amplify part of the 16S rRNA gene by polymerase chain reaction (PCR).

RESULTS

Bacterial DNA was detected in 50 of the 56 aneurysm samples (89.2%). A. actinomycetemcomitans was found in four samples (7.1%). None of the samples was positive for T. denticola, T. forsythensis, or P. gingivalis.

CONCLUSION

Bacteria are commonly present in aortic aneurysms and may play a role in the development of the condition. Periodontal pathogens are also present.

[Relationship between periodontitis and lifestyle and health status]

The purpose of this study is to clarify the relationship between periodontitis and lifestyle and health status. The subjects were 349 male workers aged on 40s and 50s, who had been working on the development and manufacture of computers. Multiple logistic regression analysis showed that the existence of periodontitis was associated positively with age, the Brinkman index, systolic blood pressure, number of white blood cells, feeling of irritation, and negatively with the use of interdental cleaners. It is therefore important to practice more active oral health promotion in cooperation with the medical staff concerned, as a part of THP (Total Health Promotion) in the workplace.

Osteomyelitis of the ribs in the antibiotic era

A total of 106 cases of rib osteomyelitis were reviewed, including 2 cases described in detail. Mycobacterial and bacterial infections accounted for 47 cases each. Fungal rib osteomyelitis occurred in 11 cases and 1 case was caused by Entamoeba histolytica. Most cases occurred in children and young adults. The mean duration of symptoms before diagnosis was 16, 26 and 32 weeks for bacterial, mycobacterial and fungal rib osteomyelitis, respectively. Common clinical signs were fever (73%), soft tissue mass (64%) and chest pain (60%). Route of infection was defined in 85 cases: 62% from contiguous spread and 38% via haematogenous route of infection. Eighty-nine percent had a favourable outcome after antimicrobial therapy with or without surgery. In conclusion, rib osteomyelitis is a rare infection of various aetiologies. The majority of cases occur in children and young adults and its diagnosis is usually delayed for several weeks.

Heterogeneity of Actinobacillus actinomycetemcomitans strains in various human infections and relationships between serotype, genotype, and antimicrobial susceptibility

Actinobacillus actinomycetemcomitans, an oral pathogen, only occasionally causes nonoral infections. In this study 52 A. actinomycetemcomitans strains from 51 subjects with nonoral infections were serotyped and genotyped by arbitrarily primed PCR (AP-PCR) to determine whether a certain clone(s) is specifically associated with nonoral infections or particular in vitro antimicrobial susceptibility patterns. The promoter structure of leukotoxin genes was additionally investigated to find the deletion characteristic of highly leukotoxic A. actinomycetemcomitans strains. The nonoral A. actinomycetemcomitans strains included all five known serotypes and nonserotypeable strains, the most common serotypes being b (40%) and c (31%). AP-PCR distinguished 10 different genotypes. A. actinomycetemcomitans serotype b strains were more frequently found in blood samples of patients with bacteremia or endocarditis than in patients with focal infections. One AP-PCR genotype was significantly more frequently found among strains originating in focal infections than in blood samples. Resistance to benzylpenicillin was significantly more frequent among A. actinomycetemcomitans serotype b strains than among strains of other serotypes. No differences in the leukotoxin gene promoter region or benzylpenicillin resistance between nonoral and oral A. actinomycetemcomitans strains were observed. Nonoral A. actinomycetemcomitans strains showed great similarity to the oral strains, confirming that the oral cavity is the likely source of nonoral A. actinomycetemcomitans infections. The predominance of serotype b strains in endocarditis and bacteremia supports the hypothesis of a relationship between certain A. actinomycetemcomitans clones and some nonoral infections. The mechanisms behind the exceptionally high rate of occurrence of benzylpenicillin resistance among A. actinomycetemcomitans serotype b strains are to be elucidated in further studies.

Characterization of serologically nontypeable Actinobacillus actinomycetemcomitans isolates

Our previous studies have shown that Actinobacillus actinomycetemcomitans isolates of a given arbitrarily primed PCR (AP-PCR) genotype belong to the same serotype (of serotypes a through e). In the present study we investigated whether the AP-PCR genotypes of nonserotypeable A. actinomycetemcomitans isolates match those of the serotypeable isolates. The isolates were additionally characterized by restriction analysis of the apaH PCR amplification products. The material included 75 nonserotypeable and 18 serotypeable A. actinomycetemcomitans isolates from 34 epidemiologically unrelated subjects. The serotypeable isolates were obtained from subjects who also harbored nonserotypeable isolates. Eight AP-PCR genotypes were distinguished among the isolates; six genotypes matched those detected in our previous studies, whereas two genotypes were new. Intraindividually, the A. actinomycetemcomitans isolates produced identical AP-PCR banding patterns, regardless of whether they were serotypeable or nonserotypeable, in 22 of 23 subjects participating with multiple isolates. AP-PCR genotype 3, corresponding to serotype c, was by far the most common among the nonserotypeable isolates (62% of subjects). Results obtained with the apaH restriction analysis confirmed the results obtained with AP-PCR for 31 of the 34 subjects. The results suggest that nonserotypeable A. actinomycetemcomitans isolates originate from serotypeable isolates, especially from serotype c isolates, and the likelihood of the existence of additional serotypes is small.

Actinobacillus actinomycetemcomitans pneumonia with chest wall and subphrenic abscess

A 14-year-old girl had progressive dyspnea and right lower chest pain for about 1 1/2 months and a weight loss of 3 kg in 2 months. Chest X-ray revealed right pleural effusion and a round infiltration over the right lower chest, initially suspected to be malignant. Image study revealed consolidation in the right middle and lower lobes with abscess-like lesions around the right lower pleura and transdiaphrenic involvement to the subphrenic region. The lesion had also invaded the intercostal muscle. The pleural abscess was obtained by fiberoptic thoracoscopy, and culture of the pus grew typical colonies of Actinobacillus actinomycetemcomitans. After the causative microorganism had been identified, cefoxitin was given for 2 weeks followed by oral amoxicillin (250 mg/6 h) for a total period of 3 months. Follow-up chest X-ray revealed resolution of the lung lesions and the patient recovered gradually without any sequelae.