July - September 2007: 
Volume 20, Issue 3

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Pulmonary Actinomycosis
Summary. The case is reported of pulmonary actinomycosis in a middle-aged woman, a smoker, who had clinical and radiological findings of a tumour-like lesion. The diagnosis was made by CTguided fine needle aspiration biopsy, which revealed tissue rich in actinomycetes. Treatment with a course of penicillin was effective, with complete resolution of the pulmonary lesions and with no relapse four years after the completion of treatment. Pneumon 2007; 20(3):249-252.
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Actinomycosis is caused by Actinomyces, a gram-positive, suppurative, filamentous, anaerobic, or microaerophilic, slow-growing bacterium. It is an immotile bacterium, non-acid-fast, non-sporeforming, and it does not produce indole or katalase.

The species most commonly found is Actinomyces israelii and A. naeslundii, A. odontolyticus, A. viscosus, A. meyeri and Arachnia propionica are less commonly encountered.

Actinomyces belong to the same family as Nocardia asteroides. They are saprophytic organisms of the oral cavity, found within the gingival crevices, in decayed teeth and in dental tartar and tonsillar crypts, or as a commensal of the gastrointestinal tract and the vagina.1-3

Actinomycosis occurs in several forms: cervicofacial (55%), abdominopelvic (20%), thoracic (15%) and the mixed organ form (10%). In the latter form, skin, brain, pericardium and limbs are involved, due to haematogenous dissemination. Chest wall invasion occurs in 12% of cases of the thoracic form.4

Pulmonary actinomycosis is rare and usually chronic. It most commonly affects men, usually aged 30-50 years, and the reported male-to-female ratio is 3:1.1,4 Actinomycosis is usually related to poor dental hygiene and is most commonly found among immunocompromised patients.3,5,6 It is found less often in the younger age group because of better control of dental decay, and less common periodontal disease in younger people.7 This disease mimics other conditions such as lung cancer, tuberculosis or lung abscess. The interest of the reported case lies in its resemblance to lung cancer.

Case presentation

The patient was a 47 year-old woman, a housewife, a smoker of 30 pack-years. She presented with a dental abscess, with spontaneous drainage, in June 2002, and was found to have decayed teeth and periodontal disease. Symptoms that followed were fatigue, joint pains and a weight loss of 3 kg in one month. On 23-6-02 she appeared with a cough and chills and a fever of up to 37.8oC, while on 26-6-02 she developed strong right-sided pleuritic chest pain. On physical examination on 29-6-02 she was found to have friction rub over the right chest and her decayed teeth with periodontal disease were noted. She had BP 130/80mmHg, pulse rate 76/min, no lymph nodes were palpable, and there were no abnormal findings in the hypochondria.

Blood tests revealed mild anaemia, with Ht 34.8%, Hb 11.2gr/dl, MCV 85.6, MCH 27.7pg, MCHC 32.3%, WBC 7,200 with 71% neutrophils and 24% lymphocytes, platelets 250.000/μL, serum Fe 19mg%, ESR 85mm in the first hour, blood urea 24mg/Dl, SGOT 15U/L. Urine tests, Wright-Widal reactions, Ra test, CPR and antiechinococcal antibodies were negative.

Postero-anterior chest X-ray and chest computed tomography (CT) revealed two round uniform masses with clear borders, measuring 2x3cm, located in the right upper and middle lobes of the lung, frontally and peripherally, with enlarged mediastinal lymph nodes (Fig. 1).

Figure 1. Chest X-ray (1a) and chest CT (1b and 1c) showing two similar masses in the right middle and upper lung fields and mediastinal lymph node enlargement.

Brain and upper and lower abdominal CT, isotope scanning of the bones and mammography showed no abnormal findings.

On 2-7-02, the patient underwent CT guided fine needle aspiration biopsy (FNA) of the lesion in the right upper lobe of the lung. The aspirated material was smeared on cytology glass slides, and examined in the cytopathology laboratory after staining with Giemsa and Papanikolaou stains. Microscopic examination revealed numerous polymorphonuclear leucocytes, erythrocytes and great number of microorganisms morphologically consistent with Actinomyces spp.

On 8-7-02, treatment was started, with 20 million units of Penicillin-G per day I.V., divided into 4 doses, for a month, followed by tablets of Penicillin-V, 6 million units/per day, divided into 4 doses P.O., for a total of six months. Three days after the start of treatment, the fever and cough disappeared, and the fatigue subsided and weight was regained over the next three weeks, while the ESR fell to 20-25mm and Ht increased to 37.2%. Radiological examination showed gradual diminution in size of the lesions, with complete resdution three months after the onset of treatment (Fig. 2).

Figure 2. Postero-anterior chest X-ray, three months after the start of treatment, with complete resolution of pulmonary shadows, except for minimal residual fibrotic lesions in the right lung.

The treatment was well tolerated, without any clinical side effects or abnormal laboratory findings. Since then, the patient has remained asymptomatic with no abnormal laboratory or radiological findings, except of some minimal residual fibrotic changes on chest X-ray.


Actinomyces spp., although misclassified as fungi, belong to the bacteria, since they have a cell wall and are sensitive to antibacterial agents and resistant to antifungal agents.3,7 The organism invades the pulmonary system through the bronchial tree, either after aspiration of oropharyngeal secretions or after influx of gastric material into the respiratory tract or inhalation of material contaminated with Actinomyces. Poor oral hygiene, oral trauma, dental procedures, status epilepticus or a large diaphragmatic hernia usually precede the development of a pulmonary lesion. Other routes of dissemination to respiratory tract may be through a tracheo-oesophageal fistula or by direct spread of cervicofacial or abdominalpulmonary forms of the disease. It can also occur under conditions of immunosupression, alcoholism or malnutrition. 2,3,6 Pulmonary actinomycosis can extend to pleura as pleural effusion, to the pericardium or to the chest wall as a fistula.

In neglected cases, haematogenous dissemination can take place.4,7 In the case described above, the disease was probably related to the earlier dental abscess.

Cough, low-grade fever, chest pain and haemoptysis are the commonest presenting symptoms of the disease. In chronic forms of the disease, sinuses and fistulae, localized chest wall swelling, empyema, hypertrophic osteoarthropathy and amyloidosis can occur.3,4

Single or multiple pulmonary masses, usually with bronchogram and lessening of the shadow in the centre of the lesion, are the usual radiological findings. The «open bronchus» sign is helpful for the differential diagnosis from lung cancer, in which bronchi are obstructed or compressed, with the exception of bronchiolo-alveolar carcinoma in which the bronchi may remain open.1,4,8 The mediastinal lymph nodes are usually enlarged, sometimes with calcifications or compression effects, such as the supra-vena-cava syndrome.1,4 In the reported case, there were two well defined masses, with no diminishing of the central shadow and no bronchogram, but with enlarged mediastinal lymph nodes, and a friction rub on auscultation, findings suggesting the diagnosis of lung cancer (fig. 1).

The diagnosis of actinomycosis is confirmed by finding actinomycetes in examined material, when there has been no possibility of colonization. Bacterial culture confirmation is usually obtained in only 50% of cases. This high percentage of false-negative culture results is due to difficulties in culturing of Actinomyces, coexisting bacterial overgrowth, easier growth of anaerobic bacteria in the specific culture media, or to previous antibiotic therapy.4,5 Conversely, culture of sputum or bronchial secretions may give false positive results in over 1/3 of cases, because Actinomyces is a bacterium of the normal flora of saliva.

Transbronchial or FNA biopsy can lead to diagnosis, either by culture or by the morphological findings of Actinomyces as in this case. The possibility of coexistence of actinomycosis and neoplastic disease must be considered, and further examination towards excluding this must not be overruled.2,3

Long-term use of Penicillin in high doses, for at least six months, is the treatment of choice. In the case described there was an immediate and complete response. Other antibiotics that can be used are ampicillin, amoxicillin, clindamycin and roxithromycin.1,3 In persistent cases or in the event of life threatening haemoptysis, surgical treatment may be needed.5,8

In conclusion, pulmonary actinomycosis is an infection with an excellent prognosis, which can be totally cured when recognized early and when appropriate antibiotic treatment is administered. This presupposes correct and timely diagnosis, by confirmation of the existence of actinomycetes in biological material with no possibility of colonization. While pulmonary actinomycosis can mimic other pulmonary diseases, especially lung cancer, the disease must be considered in the differential diagnosis of pulmonary lesions, and when confirmed, an unnecessary surgical procedure can be avoided. In some cases, when the diagnosis of actinomycosis is not confirmed by biopsy, or when there is a serious complication, a diagnostic or therapeutic surgical procedure may be necessary.


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