Actinomycosis

Abstract

Actinomycosis is a chronic suppurative infection of the cervicofacial region caused by Actinomyces species, which are anaerobic, gram-positive filamentous bacteria. Although actinomycosis has a propensity for involving the oral cavity, rare cases of actinomycosis involving the temporal bone have been published. We report the case of a 14-year-old girl who presented with clinical, audiometric, and radiologic findings consistent with right chronic suppurative otitis media that persisted despite tympanomastoidectomy. Findings on histologic evaluation of a specimen obtained during revision surgery were consistent with a diagnosis of actinomycosis. Although actinomycosis of the temporal bone is rare, it should be considered in the differential diagnosis of chronic suppurative temporal bone infections that are resistant to standard therapy.

Introduction

Actinomycosis is a chronic suppurative infection caused by an anaerobic, gram-positive, nonacid-fast, filamentous bacterium. (1) Actinomyces israelii is the most common pathogenic species of this bacteria found in humans. (2) Although Actinomyces is part of the normal flora of the oral cavity, it has been known to cause chronic suppurative infections of the oral cavity region, usually after minor trauma resulting in mucosal breaks. (1,2) Patients with such an infection classically present with a chronically draining wound that has a "woody" consistency and purulent discharge draining from multiple sinus tracts.

The most common sites of Actinomyces infection are the cervicofacial region (~55% of cases), (3) the abdomen, and the thorax. (4) In rare cases, actinomycosis involves the temporal bone region. (4-10) In this article, we report a new case of actinomycosis of the temporal bone.

Case report

A 14-year-old girl presented with a long-standing history of right aural fullness, otalgia, hearing loss, and recurrent otorrhea that had been unresponsive to multiple courses of oral and topical antibiotics. Because cholesteatoma had been suspected during a previous evaluation, she had undergone a right intact canal wall tympanomastoidectomy; however, this procedure failed to alleviate her symptoms.

Physical examination of the right ear revealed the presence of a thick, foul-smelling, yellow drainage; the tympanic membrane was intact. Findings on examination of the left ear and the rest of her head and neck were unremarkable. Audiometry revealed that she had a 40-dB, flat, conductive hearing loss on the right side. Computed tomography (CT) demonstrated a complete opacification of the right middle ear and mastoid (figure 1).

[FIGURE 1 OMITTED]

The patient underwent a right revision intact canal wall tympanomastoidectomy and placement of a myringotomy tube. The tympanic membrane and ossicles were normal, but the middle ear and mastoid were filled with granulation tissue. Histopathologic evaluation demonstrated fragments of respiratory mucosa with marked acute and chronic inflammatory cells and sulfur granules, findings that are consistent with actinomycosis (figure 2). Postoperatively, the patient was placed on oral penicillin for 6 months, and she remained asymptomatic at the 2year follow-up.

[FIGURE 2 OMITTED]

Discussion

Actinomyces, a commensal organism of the oral cavity, is often found in the tonsillar crypts, where it exists asymptomatically. (4) Risk factors for the development of a cervicofacial infection include poor dental hygiene, dental manipulations, and maxillofacial trauma, which enable the organism to breach the mucosa. (2) Once in the submucosal tissues, the organism causes a chronic, suppurative infectious process that has a characteristic clinical course.

Clinically, actinomycosis presents as an insidious-on set, chronic suppurating wound that is characterized by multiple draining sinus tracts. Pain is often not a significant feature at presentation, but low-grade fever is documented in approximately 50% of cases. (2) Prolonged infection results in extensive fibrosis, which imparts a firm, woody consistency to the involved tissues. Spread of the infection occurs by direct extension, and it can progress to involve adjacent bone, resulting in osteomyelitis. (2)

A diagnosis of actinomycosis is often suggested by the presence of pale-yellow clusters of sulfur granules, which are made up of tangled filaments of Actinomyces organ isms, seen in discharge fluid or on microscopic evaluation of infected tissue. (1) Demonstration of the organism itself on histopathology can be facilitated by using special staining techniques. In light of the typical lack of preoperative suspicion and the fastidious nature of this organism, Actinomyces is difficult to culture. Cultures are negative in more than 70% of cases, even in patients whose clinical features meet other diagnostic criteria. (2) Whenever actinomycosis is suspected, acid-fast testing should be performed to differentiate between Actinomyces and Nocardia species. Nocardia species are acid-fast--staining, whereas Actinomyces are not. (2) Diagnostic aids, including CT, are nonspecific and useful only in defining the extent of the disease process in the involved region. (2)

The management of cervicofacial actinomycosis en tails surgical debridement and long-term antibiotic therapy. Prolonged courses of antibiotic therapy are necessary in order to minimize the risk of recurrence. Penicillin is the agent of choice; the route and duration of therapy depend on the severity of the infection. For minor infections, 2 months of oral penicillin V may be sufficient. (1) More severe infections should be treated with 4 to 6 weeks of parenteral penicillin G followed by 6 to 12 months of oral penicillin V. (1) Patients who are allergic to penicillin can be adequately treated with a number of other antibiotics, including tetracycline, erythromycin, clindamycin, and chloramphenicol. (1)

Fewer than 30 cases of actinomycosis involving the temporal bone have been reported in the literature. Temporal bone infection is believed to be caused by the spread of the organism from the pharynx to the middle ear via the eustachian tube. (8,10) Once present in the temporal bone region, the infection spreads through breaks in the mucosa, which allow it to travel between tissue planes. (9) Although actinomycosis involving the temporal bone is rare, it should be considered in the differential diagnosis of chronic suppurative temporal bone infections that are resistant to standard therapy.

The presentations of most patients with temporal bone actinomycosis have been similar to those of patients with chronic suppurative otitis media--that is, these infections were characterized by a prolonged, indolent course and were refractory to conservative treatment. (4-9) During the preantibiotic era, actinomycosis of the temporal bone was almost always fatal, usually as a result of intracranial spread of infection. (10) According to reports of these early cases, most patients died suddenly after being relatively symptom-free. The diagnosis in these cases was often made at autopsy.

During surgery, granulation tissue and a yellow, cheesy discharge are often seen in the middle ear and mastoid The diagnosis of temporal bone actinomycosis is usually based on histopathologic examination of biopsy specimens obtained during surgery. (5,7,9) Our patient presented with a history and physical examination typical of chronic suppurative otitis media; we based our diagnosis solely on the histopathologic findings.

Once the diagnosis of actinomycosis otomastoiditis has been made, the infection should be treated in the same way one would treat a typical cervicofacial Actinomyces infection, with surgical debridement and a prolonged course of a systemic antibiotic. Most authors report successful resolution of the infection with a combination of tympanomastoidectomy followed by a 3- to 6-month course of penicillin. (5,7) Shelton and Brackmann have also advocated aerating the infected site to create an aerobic environment in order to hinder Actinomyces survival. (5) Having been managed in this fashion, our patient remained free of disease at the 2-year follow-up.

References

(1.) Smego RA, Jr., Foglia G. Actinomycosis. Clin Infect Dis 1998; 26:1255-61.

(2.) Belmont MJ, Behar PM, Wax MK. Atypical presentations of actinomycosis. Head Neck 1999;21:264-8.

(3.) Bennhoff DF. Actinomycosis: Diagnostic and therapeutic considerations and a review of 32 cases. Laryngoscope 1984;94:11981217.

(4.) Ajal M, Turner J, Fagan P, Walker P. Actinomycosis oto-mastoiditis. J Laryngol Otol 1997;111:1069-71.

(5.) Shelton C, Brackmann DE. Actinomycosis otitis media. Arch Otolaryngol Head Neck Surg 1988;114:88-9.

(6.) Boor A, Jurkovic I, Friedmann I, et al. Actinomycosis of the middle ear. J Laryngol Otol 1998;112:800-1.

(7.) Olson TS, Seid AB, Pransky SM. Actinomycosis of the middle ear. Int J Pediatr Otorhinolaryngol 1989; 17:51-5.

(8.) Leek JH. Actinomycosis of the tympanomastoid. Laryngoscope 1974;84:290-301.

(9.) Tarabichi M, Schloss M. Actinomycosis otomastoiditis. Arch Otolaryngol Head Neck Surg 1993;119:561-2.

(10.) Risch OC. Actinomycosis of the ear. Arch Otolaryngol Head Neck Surg 1939;29:235-51.

From the Division of Otolaryngology, Department of Surgery, The Children's Hospital of Philadelphia, and the Department of Otorhinolaryngology--Head and Neck Surgery, University of Pennsylvania School of Medicine, Philadelphia.

Reprint requests: Ralph F. Wetmore, MD, Division of Otolaryngology, Department of Surgery, The Children's Hospital of Philadelphia, Richard D. Wood Center, 1st Floor, 34th and Civic Center Blvd., Philadelphia, PA 19104-4399. Phone:(215) 590-1582;fax:(215) 590-3986; e-mail: wetmore@email.chop.edu

Originally presented at the annual meeting of the Society for Ear, Nose, and Throat Advances in Children; Dec. 6, 2002; Atlanta.

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