Nocardia infection in splenectomized patients: case reports and a review of the literature

A Case of Bilateral Nocardia francinia Adrenal Abscesses in an Intravenous Drug-Using Splenectomized Patient With Tricuspid Endocarditis

Adrenal abscesses due to disseminated nocardiosis are exceedingly rare in clinical practice, and to date only 8 cases have been reported in the literature, most of which were confined to a single adrenal gland. These infections often occur in patients with underlying immune deficiency. We report a rare case of bilateral nocardial adrenal abscesses in an intravenous drug–using splenectomized patient that presumably originated from direct inoculation using intravenous opana, as his admission chest radiograph was normal.

Differential Role of Rapamycin and Torin/KU63794 in Inflammatory Response of 264.7 RAW Macrophages Stimulated by CA-MRSA

Background. Rapamycin suppresses the RAW264.7 macrophage mediated inflammatory response but in lower doses induces it. In the present study, we tested the suppression of the inflammatory response in the presence of mTOR 1 and 2 inhibitors, Torin and KU63794. Methods. RAW264.7 cells were stimulated for 18 hrs with 10⁶ to 10⁷ CFU/mL inocula of community-acquired- (CA-) MRSA isolate, USA400 strain MW2, in the presence of Vancomycin. Then, in sequential experiments, we added Torin, KU63794, and Rapamycin alone and in various combinations. Supernatants were collected and assayed for TNF, IL-1, IL-6, INF, and NO. Results. Rapamycin induces 10–20% of the inflammatory cascade at dose of 0.1 ng/mL and suppresses it by 60% at dose of 10 ng/mL. The induction is abolished in the presence of Torin KU63794. Torin and KU63794 are consistently suppressing cytokine production 50–60%. Conclusions. There is a differential response between Rapamycin (mTOR-1 inhibitor) and Torin KU63794 (mTOR 1 and 2 inhibitors). Torin and KU63794 exhibit a dose related suppression. Rapamycin exhibits a significant induction-suppression biphasic response. Knowledge of such response may allow manipulation of the septic inflammatory cascade for clinical advantages.

Systemic Nocardiosis in a Splenectomized Patient with Systemic Lupus Erythematosus

A splenectomized patient with systemic lupus erythematosus, who had previously been treated with high doses of corticosteroids, presented with headaches and symptoms of a respiratory tract infection. A magnetic resonance imaging scan of the brain revealed a ring-enhancing lesion, and Nocardia asteroides was isolated from a stereotactic biopsy specimen. After adverse reactions to a number of antibiotics, infection control was finally achieved by the new oxazolidinone drug, linezolid. Nocardiosis should be considered as a differential diagnosis in all immunocompromised patients who develop an obscure infection; delay in diagnosis and subsequent initiation of appropriate treatment often results in a fatal outcome. Linezolid is a new option for the treatment of nocardiosis and is effective when given orally.

Nocardiosis in systemic lupus erythematosus

OBJECTIVES

This study was performed to study the clinical presentations, treatment, and outcome of six cases of nocardial infection in the systemic lupus erythematosus (SLE) population living in Hong Kong and compare these cases with those reported in the English literature.

METHODS

Records of 215 SLE patients who attended our lupus and rheumatology clinics were reviewed, and cases of nocardial infection were retrieved and studied in detail. A Medline search from 1966 to 1995 was performed to identify other reported cases. The microbiology, diagnosis, and treatment strategies of nocardiosis were assessed.

RESULTS

Six cases of nocardiosis were found in our lupus series, giving a prevalence of 2.8%. Another 26 cases of nocardial infection in SLE were reported in the literature. All except one were caused by Nocardia asteroides. The lung was the commonest site of involvement (81%), followed by the central nervous system (CNS) (13%). The mortality was high (35%), especially when the CNS was involved (75%). Sulphonamides were the mainstay of treatment, and adjunctive surgical procedures may be needed for suppurative complications.

CONCLUSIONS

Nocardiosis has been increasingly recognized in SLE. Although still uncommon, it is an important opportunistic infection because it is curable and mortality is usually caused by delay in diagnosis and treatment. A high index of suspicion, an aggressive approach to diagnosis, and early empirical therapy are essential principles of management.

Human nocardiosis in northern Italy from 1982 to 1992. Northern Italy Collaborative Group on Nocardiosis

We conducted a retrospective survey of nocardiosis in 9 city hospitals in northern Italy from 1982 to 1992. The medical records of 30 patients with documented nocardiosis were reviewed. Microbiological data included morphology, biochemical characteristics, serology and in vitro susceptibility testing. The 29 isolates (1 case was diagnosed on the basis of serological results) were Nocardia asteroides (n = 25) and Nocardia farcinica (n = 4). Predisposing factors including immunosuppression for organ transplant rejection prophylaxis, lung disease (silicotuberculosis and pulmonary fibrosis), solid tumours and hematological malignancies, and AIDS. Three patients had no identified risk factors. 20 cases of pulmonary nocardiosis were observed. Sites of infection in patients without previous pulmonary involvement were: brain abscesses, soft tissues, pericardium, blood, and cerebrospinal fluid. Most strains tested were susceptible to amikacin and imipenem. Resistance to several antimicrobial agents was found, particularly erythromycin, fosfomycin, pefloxacin, sulphonamides and trimethoprim. Antimicrobial chemotherapy included sulphonamides, amikacin, ceftriaxone, imipenem and minocycline. 21 patients survived, although 2 relapsed transiently. Nocardiosis appears to be more common than generally realised by physicians in northern Italy. The local species distribution and disease spectrum are similar to those described elsewhere. Nocardiosis should be part of the differential diagnosis in patients with pulmonary infiltrates or brain abscess, particularly those with predisposing factors.

The medically important aerobic actinomycetes: epidemiology and microbiology

The aerobic actinomycetes are soil-inhabiting microorganisms that occur worldwide. In 1888, Nocard first recognized the pathogenic potential of this group of microorganisms. Since then, several aerobic actinomycetes have been a major source of interest for the commercial drug industry and have proved to be extremely useful microorganisms for producing novel antimicrobial agents. They have also been well known as potential veterinary pathogens affecting many different animal species. The medically important aerobic actinomycetes may cause significant morbidity and mortality, in particular in highly susceptible severely immunocompromised patients, including transplant recipients and patients infected with human immunodeficiency virus. However, the diagnosis of these infections may be difficult, and effective antimicrobial therapy may be complicated by antimicrobial resistance. The taxonomy of these microorganisms has been problematic. In recent revisions of their classification, new pathogenic species have been recognized. The development of additional and more reliable diagnostic tests and of a standardized method for antimicrobial susceptibility testing and the application of molecular techniques for the diagnosis and subtyping of these microorganisms are needed to better diagnose and treat infected patients and to identify effective control measures for these unusual pathogens. We review the epidemiology and microbiology of the major medically important aerobic actinomycetes.

Nocardia species: host-parasite relationships

The nocardiae are bacteria belonging to the aerobic actinomycetes. They are an important part of the normal soil microflora worldwide. The type species, Nocardia asteroides, and N. brasiliensis, N. farcinica, N. otitidiscaviarum, N. nova, and N. transvalensis cause a variety of diseases in both normal and immunocompromised humans and animals. The mechanisms of pathogenesis are complex, not fully understood, and include the capacity to evade or neutralize the myriad microbicidal activities of the host. The relative virulence of N. asteroides correlates with the ability to inhibit phagosome-lysosome fusion in phagocytes; to neutralize phagosomal acidification; to detoxify the microbicidal products of oxidative metabolism; to modify phagocyte function; to grow within phagocytic cells; and to attach to, penetrate, and grow within host cells. Both activated macrophages and immunologically specific T lymphocytes constitute the major mechanisms for host resistance to nocardial infection, whereas B lymphocytes and humoral immunity do not appear to be as important in protecting the host. Thus, the nocardiae are facultative intracellular pathogens that can persist within the host, probably in a cryptic form (L-form), for life. Silent invasion of brain cells by some Nocardia strains can induce neurodegeneration in experimental animals; however, the role of nocardiae in neurodegenerative diseases in humans needs to be investigated.

Nocardia species: host-parasite relationships

The nocardiae are bacteria belonging to the aerobic actinomycetes. They are an important part of the normal soil microflora worldwide. The type species, Nocardia asteroides, and N. brasiliensis, N. farcinica, N. otitidiscaviarum, N. nova, and N. transvalensis cause a variety of diseases in both normal and immunocompromised humans and animals. The mechanisms of pathogenesis are complex, not fully understood, and include the capacity to evade or neutralize the myriad microbicidal activities of the host. The relative virulence of N. asteroides correlates with the ability to inhibit phagosome-lysosome fusion in phagocytes; to neutralize phagosomal acidification; to detoxify the microbicidal products of oxidative metabolism; to modify phagocyte function; to grow within phagocytic cells; and to attach to, penetrate, and grow within host cells. Both activated macrophages and immunologically specific T lymphocytes constitute the major mechanisms for host resistance to nocardial infection, whereas B lymphocytes and humoral immunity do not appear to be as important in protecting the host. Thus, the nocardiae are facultative intracellular pathogens that can persist within the host, probably in a cryptic form (L-form), for life. Silent invasion of brain cells by some Nocardia strains can induce neurodegeneration in experimental animals; however, the role of nocardiae in neurodegenerative diseases in humans needs to be investigated.