Corynebacterium afermentans lung abscess and empyema in a patient with human immunodeficiency virus infection.

Abstract: Necrotizing pleuropulmonary infection in a patient with acquired immunodeficiency syndrome developed due to Corynebacterium afermentans subspecies lipophilum. Long-term combination antibiotic therapy was successful in eradicating the infection without surgery.

Key Words: Corynebacterium, human immunodeficiency virus, lung abscess

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Corynebacterium species are unusual opportunistic pathogens in immunocompromised patients, including individuals with human immunodeficiency virus (HIV) infection. Although sometimes dismissed as contaminants, Corynebacterium species have been reported to cause significant and life-threatening infections, including bacteremia, device infections, endocarditis, and abscesses in immunocompromised patients. C afermentans subspecies lipophilum is difficult to recover and has not been reported to cause pleuropulmonary infection. We report a first documented case of a lung abscess with empyema due to C afermentans subspecies lipophilum in a patient with HIV infection.

Case Report

A 27-year-old Hispanic female with HIV infection presented to the hospital with fever, chills, pleuritic chest pain, and cough. The patient had HIV infection for 10 years. Her CD4 lymphocyte count was 34/m[m.sup.3], and her viral load was 31,000 copies/mL despite treatment with a highly active antiretroviral regimen. Her chest radiograph demonstrated right lower lobe infiltrate and effusion. She was treated with ceftriaxone and erythromycin for presumed community-acquired pneumonia. Diagnostic thoracentesis revealed that her protein was 4.7 g/dL, her lactate dehydrogenase was 1,442 U/dL, and her leukocyte count was 6,500/m[m.sup.3] (88% neutrophils). Chest tube placement was attempted unsuccessfully. Pleural fluid culture grew C afermentans subsp lipophilum. Blood cultures at that time were negative. The patient was discharged to home with clinical improvement after 2 weeks of therapy.

Three weeks later, she presented with similar symptoms; treatment with levofloxacin was initiated, but the pulmonary infection progressed to abscess formation. Chest computed tomographic scan demonstrated a right lower lobe 7.5 X 7-cm complex mass-like opacity with associated pleural effusion (Fig. 1). Blood and pleural fluid cultures grew C afermentans subsp lipophilum. Sensitivity testing revealed the organism to be susceptible to imipenem, vancomycin, and trimethoprim-sulfamethoxazole. Sputum cultures revealed normal respiratory flora.

The patient received outpatient therapy with imipenem, azithromycin, and rifampin. Her fever and respiratory symptoms resolved. A computed tomographic scan after 6 months of antibiotic therapy demonstrated complete resolution of the abscess and effusion. Surgical intervention was not required.

Discussion

Corynebacteria are Gram-positive, non-acid-fast, aerobic or facultatively anaerobic, asporogenous rods. A wide variety of colonial types are found within the genus. Among the reasons for the difficulty in speciating these organisms are that many require special growth media, most have highly variable biochemical characteristics, and most grow slowly. (1-4) The isolation of Corynebacterium may be overlooked as reflecting a skin contaminant. Increasingly, however, these saprophytic organisms are being recognized as pathogens. Many nondiphtheric corynebacteria have been isolated in the setting of respiratory tract infections in immunocompromised patients.

Rhodococcus equi, formerly C equi, has been recognized as an opportunistic pathogen, with 82% of patients presenting with pneumonia. (5) Cavitation is described in more than 50% of patients, and pleural effusion is reported in approximately 20% of patients. Blood cultures are positive in half of the patients. (5) Combination antibiotic therapy is usually sufficient to eradicate the infection (6,7); however, surgical resection may be required for large abscess formation. (8) C pseudodiphthericum has been described as a cause of alveolar infiltrates and lung abscess in HIV-positive patients. (9) Cavitation and pleural effusion have been present in approximately one third of affected individuals. Most patients have recovered with prolonged antibiotic therapy. C striatum has also been isolated as the etiologic agent of pleuropulmonary infections in patients with acquired immunodeficiency syndrome. (10) Corynebacteria group JK, C ulcerans, and C xerosis are reported to cause pulmonary infections in non-HIV immunocompromised patients. (11-13)

[FIGURE 1 OMITTED]

C afermentans subsp lipophilum was first isolated in 1993. (14) This was the new name for the Centers for Disease Control and Prevention coryneform group ANF-1 (absolute nonfermenter). The original strains were blood-culture isolates, and the three reported clinical cases included a central venous catheter infection, prosthetic valve endocarditis with perivalvular abscess formation, and brain and liver abscesses. (1,2) Lipophilic corynebacteria may require extended incubation to be recovered. (1) [beta]-Lactam susceptibility is variable. (1,2) Therapy is initiated with two antibiotics, one of which must provide macrophage penetration. Vancomycin or imipenemcilastatin would be adequate agents for this purpose. Some clinicians would also add an aminoglycoside to this regimen. Fluoroquinolone, macrolide, and rifampin can be used in conjunction, depending on the sensitivity. (15) Antibiotics are administered for at least 2 months; longer administration is guided by the clinical and radiographic response. Relapses are frequently seen with shorter courses.

Our patient presented with progressive, necrotizing, pleuropulmonary infection due to C afermentans, similar to that of R equi infection. C afermentans was isolated early from pleural fluid but was not appreciated as a pathogen. This delayed appropriate therapy, during which time the abscess progressed. In contrast to patients reported in the literature with large abscess formation, combination antibiotic therapy was successful and surgical intervention was not required. Our patient had severe CD4 lymphocyte depletion despite treatment with antiretroviral therapy. There are insufficient data from the literature to assume that acquisition of Corynebacterium infection is limited only to patients with extremely low CD4 lymphocyte counts.

Conclusion

Corynebacterium species are unusual but potentially significant pathogens leading to necrotizing pleuropulmonary infections in HIV-infected patients. Diagnosis is established by culture of pleural fluid, blood, and respiratory secretions. A prolonged course of combination antibiotic therapy may be successful in eradicating the infection; however, surgical intervention may be required.

Better by far that you should forget and smile than that you should
remember and be sad.
--Christina Rossetti

Accepted June 19, 2003.

Copyright [c] 2004 by The Southern Medical Association

0038-4348/04/9704-0395

References

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11. Wallet F, Marquette CH, Courcol RJ. Multiresistant Corynebacterium xerosis as a cause of pneumonia in a patient with acute leukemia. Clin Infect Dis 1994;18:845-846 (letter).

12. Guarino MJ, Qazi R, Woll JE, et al. Septicemia, rash, and pulmonary infiltrates secondary to Corynebacterium Group JK infection. Am J Med 1987;82:132-134.

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RELATED ARTICLE: Key Points

* Corynebacterium afermentans can cause lung abscess and empyema in an immunocompromised individual.

* Corynebacterium afermentans may require a long incubation period for isolation and is frequently disregarded as a contaminant.

* A prolonged combination antibiotic regimen is needed to eradicate this significant infection, and surgery may be needed in isolated cases.

Ruth Minkin, MD, and Janet M. Shapiro, MD

From the Division of Pulmonary and Critical Care Medicine, St. Luke's-Roosevelt Hospital Center, New York, NY.

Reprint requests to Ruth Minkin, MD, Division of Pulmonary and Critical Care Medicine, St. Luke's Hospital, MU 316, 1111 Amsterdam Avenue, New York, NY 10025. Email: [e-mail]