DISCUSSION

Actinomycosis is an extremely rare infectious disease in the membranes of the oral mucosa and its clinical presentation is usually characterized by suppurative granulomatous inflammation, with abscess and fistula [2,4,10]. The reported case demonstrates unusual features of the oral infectious manifestation by Actinomyces, with ulcerative lesions on the back of the tongue, buccal mucosa and lower vestibule fundus. However, other cases found in the literature also present a clinical manifestation that may evade the pattern [2].

Predisposing factors for the onset of this condition may be local or systemic, such as poor oral hygiene, trauma, surgical procedures, diabetes, long-term corticosteroid therapy and immunosuppression. The risk of developing the disease is also increased in smokers and alcoholics [1,3]. In the case reported, the patient presented a history of cigarette and alcohol consumption and also underwent medical treatment based on systemic corticosteroids.

Another predisposing factor presented by the patient is related to immunosuppression. Transplanted patients need to use several immunosuppressive agents throughout their post-transplant life and may present an increased risk for the development of opportunistic infections, whether of viral or bacterial origin [11]. The patient underwent liver transplantation in the year 2006 and since then makes daily use of Tracolimus, which is an immunosuppressive medication, usually used with the aim of reducing the risk of rejection of the transplanted organ. Then, faced with this immunosuppression, the patient became more susceptible to the development of infectious processes, such as actinomycosis.

Treatment with systemic antimicrobials is the therapy of choice for bacterial infections by Actinomyces [3,12]. However, in the literature, the number of studies that show antimicrobial photodynamic therapy as effective in the adjuvant treatment of infectious conditions has been increasing. The aPDT presents as promising, with several applications and numerous advantages, among them, the absence of side effects and the impossibility of resistance acquired by bacteria [6,7,13].

The use of methylene blue dye has been Communty-Europen (CE)-licensed for use in dental medicine and maxillofacial surgery in Europe since 2003 and has been used for the treatment of infected wounds. The authors have used the technique in clinical practice for medication-related osteonecrosis of the jaw lesions for at least 10 years for more than 200 patients in combination with systemic antimicrobial therapy with b-lactam antibiotics combined with b-lactamase inhibitors. They have found marked improvement especially in wounds with microbiologically proven colonization with Actinomyces species [13].

The first group to report the use of mouse wound infection models to investigate the effects of PDT in treating excisional wound infected with Escherichia coli and Pseudomonas aeruginosa were Hamblin et al. [14]. The experiment consisted in a single wound realized on the backs of healthy mice and infected with a suspension of bioluminescent bacteria transduced with a plasmid containing a lux gene operon, which permitted to monitor the infection in real time by a sensitive charge-coupled camera. In PDT-treated mice, the authors observed a light dose dependent loss of luminescence with a 99% reduction after the four light aliquots, which were not seen in the untreated wound.

Regarding the efficiency of bacterial inactivation by aPDT, it is known that Gram-positive bacteria are generally more susceptible to aPDT than Gram-negative species. These differences can be explained by structural differences in cell walls [15]. As the infectious disease in question is caused by Gram-positive bacteria, it is even more appropriate to perform the aPDT as a therapeutic modality associated with systemic antimicrobials.

The exact nature of the microbial killing caused by different types of lasers emitting light in the intermediate wavelength region has not yet been determined. The laser beam effect on bacterial cells depends on laser parameters (wavelength, power, time and mode of emission, beam profile and spot size) and the characteristics of each bacterium [16].

In the scientific databases, in vitro clinical studies and case reports demonstrating the use of the laser through aPDT in the microbial inactivation of several gram positive and negative bacteria can be found, for example in cases of Pseudomonas aeruginosa, Fusarium sp. and others [13,14,16]. However, the use of this therapy in actinomycosis disease with oral infections, being then a promising therapy, used in a rare oral manifestation, with few cases described in the literature.

Therefore, health professionals should be aware of the existence of infectious diseases in the mouth, which may even mimic malignant conditions. It is extremely important that the diagnosis is correctly established so that the treatment adopted is consistent with the condition exhibited by the patient [1].

CONCLUSION

Infections are the leading causes of morbidity and mortality in liver transplant patients. The clinical diagnosis associated with microbiological culture is fundamental for confirmation of the actinomycosis disease. Infectious oral lesions by actinomyces are rare and specific antibiotic therapy is the treatment of choice for these cases. Photodynamic antimicrobial therapy (aPDT) is an adjunctive therapeutic modality in the treatment of oral bacterial infectious manifestations, with satisfactory results.