Aggregatibacter actinomycetemcomitans osteomyelitis in a 12 year old boy: case report emphasizing the importance of tissue culture, and review of literature

Aggregatibacter actinomycetemcomitans: From the Oral Cavity to the Heart Valves

Aggregatibacter actinomycetemcomitans (A. actinomycetecomitans) is a Gram-negative bacterial species that is an essential component of the oral microbiota. Due to its aggregative properties, it plays a role in the pathogenesis of human diseases. The presence of the surface proteins Fim, Briae, and microvesicles enables the bacterium to adhere to the epithelial surface and the tooth's surface. The presence of leukotoxin A (LtxA), which plays an important role in the pathogenicity of the bacterium, has been associated with both periodontitis and the etiology of rheumatoid arthritis (RA). A. actinomycetecomitans is also associated with several other systemic diseases and complications, such as endocarditis and different abscesses. In addition to leukotoxin A, A. actinomycetecomitans possesses several different virulence factors, including bacteriocins, chemotaxis inhibitory factors, cytotoxic factors, Fc-binding proteins, immunosuppressive factors, lipopolysaccharide collagenase, fibroblast inhibitory factors, antibiotic resistance determinants, adhesins, invasive factors and factors that inhibit the function of polymorphonuclear leukocytes. The ability of A. actinomycetemcomitans lipopolysaccharide to induce macrophages to secrete the interleukins IL-1, IL-1β, and tumor necrosis factor (TNF) is of considerable importance. The primary etiologic factor in the pathogenesis of periodontal disease is the oral biofilm colonized by anaerobic bacteria. Among these, A. actinomycetemcomitans occupies an important place as a facultative anaerobic bacterium. In addition, A. actinomycetemcomitans possesses many virulence factors that contribute to its potential to cause cancer. This article provides an overview of the virulence factors of A. actinomycetecomitans and its association with various systemic diseases, its oncogenic potential, and the treatment options for infections caused by A. actinomycetecomitans.

Aggregatibacter actinomycetemcomitans infection in children: two case reports and a review of the literature

Aggregatibacter actinomycetemcomitans (Aa), a Gram-negative coccobacillus commonly associated with endocarditis, poses a rare diagnostic challenge in pediatric cases. The presentation of two pediatric cases-myositis and chest mass-highlights novel aspects, including unusual symptom presentations in children which can be mistaken for malignancy. The limited sensitivity of standard blood tests complicates diagnosis, leading to delayed diagnosis and treatment. Representative samples must be taken, especially if blood cultures are negative. Despite advances in detection methods, diagnosing Aa infection remains difficult due to its rarity in children and variable clinical presentation. In conclusion, a comprehensive understanding of Aa infection in children is essential for early and effective diagnostic and therapeutic management.

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.

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.

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.

MALDI-TOF vs. VITEK 2 for identification of Aggregatibacter actinomycetemcomitans chest wall abscess

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A 56-year-old male patient has a chest wall abscess with intercostal muscle involvement.

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Aggregatibacter actinomycetemcomitans was misidentified as Pasturella canis or Pasturella multocida by the automated VITEK 2 system.

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The study re-enforces the importance of an accurate and rapid diagnosis to assist patient management.

Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) is a facultative anaerobic Gram-negative coccobacillus that is associated with a variety of diseases in humans. In the present study, the isolate finally identified as A. actinomycetemcomitans by MALDI-TOF was misidentified as Pasturella canis or Pasturella multocida by the automated VITEK 2 system. The findings re-enforce the importance of an accurate and rapid diagnosis to assist patient management.