A case series and focused review of nocardiosis: clinical and microbiologic aspects

Nocardia species are ubiquitous soil organisms that often infect patients with underlying immune compromise, pulmonary disease, or a history of surgery or trauma. We report 5 cases of nocardiosis representing various aspects of this "great imitator": 1) pneumonia in the setting of underlying malignancy, 2) chronic pneumonia with drug-resistant organism, 3) bacteremia and empyema with chronic hematologic malignancy, 4) primary cutaneous disease, and 5) sternal wound infection. We present a summary of the English literature from 1966 to 2003 with a focus on the teaching points of each of our 5 cases as well as the background epidemiology and microbiology of the Nocardia genus. Isolation of the organism may be achieved with routine media but longer incubation times may be necessary, delaying diagnosis and appropriate therapy. Treatment with a sulfa-containing regimen is standard of care, but resistance testing is warranted given emerging drug resistance, high rates of discontinuation due to adverse reactions, and the potential for nephrotoxicity in transplant recipients on cyclosporine.

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.

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.

Nocardiosis. A literature review with selected case reports in two dogs

Two dogs with systemic nocardiosis are presented and the pathobiology, diagnosis, and treatment of nocardial infections are discussed. Both dogs had nonspecific respiratory signs and depression. The diagnosis was made by isolation of the organism only after surgical drainage was established and appropriate tissues were cultured. The response to surgical drainage and antimicrobial therapy was dramatic in both dogs, but one dog experienced a drug reaction to trimethoprim-potentiated sulfonamide. Although systemic nocardial infections traditionally have had a grave prognosis, through early diagnosis, surgical intervention, and the use of newer, safer and synergistically acting antimicrobials, the prognosis has improved. This article reviews current human and veterinary literature regarding the microbiology, pathogenesis, and treatment of nocardiosis and reports on the successful treatment of systemic nocardiosis in two dogs.

Infection with Nocardia species in Queensland. A review of 102 clinical isolates

OBJECTIVE

To review the species distribution, pathologic significance and disease associations of clinical isolates of Nocardia and related bacteria in Queensland, and to examine the characteristics, treatment and outcome of patients infected with these organisms.

DESIGN AND SETTING

A retrospective review of Queensland State Health Laboratory records provided microbiological data for Nocardia isolates referred from other laboratories during the period January 1983 to December 1988. Clinical information was extracted from hospital case notes, or obtained from detailed questionnaires completed by attending physicians. Nocardia isolates were classified as "significant" if specific treatment for nocardiosis was given, or on the basis of autopsy findings.

PATIENTS

One hundred and two patients had a Nocardia species or a related organism isolated from clinical specimens during the study period.

RESULTS

The 102 isolates included Nocardia asteroides (45), N, brasiliensis (35), N. caviae (5) and N. transvalensis (5). Clinical results were available for 93 patients, of whom 74 (80%) had a significant isolate recovered. Primary pulmonary or disseminated disease occurred in 35 patients, and was caused mainly by N. asteroides. Significant infections of skin and soft tissues, primarily due to N. brasiliensis, were found in 39 patients. Preexisting lung disease and treatment with steroids and immunosuppression were risk factors for pulmonary and disseminated nocardiosis. A history of inoculation in an outdoor setting was frequent in patients with cutaneous disease. Antibiotic regimens that included trimethoprim-sulfamethoxazole or another sulfonamide agent were used to treat the majority of patients with significant infection. Deaths were confined to those with pulmonary and disseminated disease, with a case fatality rate of 40% in that group.

CONCLUSION

Infection with Nocardia species appears to be more common than is generally appreciated. The local species distribution and disease spectrum are similar to those described elsewhere. A high index of suspicion for nocardiosis should be maintained in susceptible hosts with pulmonary infiltrates, particularly when there is evidence for metastatic infection, and in patients with superficial infections and a history of outdoor injury.

An improved screening technique for isolation of Nocardia species from sputum specimens

Three selective isolation media and the paraffin baiting technique were compared with conventional culture (Sabouraud dextrose agar without antibiotic supplement) for the ability to grow and detect nocardiae from simulated sputum specimens. Modified Thayer-Martin medium, incorporating vancomycin, colistin, nystatin and trimethoprim as selective agents, produced the highest recovery rate and with the greatest suppression of normal respiratory tract flora. A clinical evaluation using a screening programme devised for a busy diagnostic microbiology laboratory was performed on 1600 sputum specimens. Inoculating sputum on modified Thayer-Martin medium and extending the initial incubation period of 3 days at 35 degrees C under 10% carbon dioxide to a further 3 weeks at room temperature in a candle jar, led to the diagnoses, which otherwise would have been missed, of pulmonary nocardiosis in 3 patients and pulmonary infections due to Neisseria meningitidis, Pseudomonas cepacia, and Serratia marcescens in a further 22 patients.

Nocardial brain abscess: diagnostic and therapeutic use of stereotactic aspiration

Three cases of nocardial brain abscess are presented. All three patients were receiving immunosuppressive therapy at the time of diagnosis. Two patients had cardiac transplantation and the third had periarteritis nodosa. The patients presented with generalized seizures or focal weakness. Accurate localization of the intracerebral mass lesion was obtained from computed tomography (CT) scans, but CT-guided stereotactic aspiration was required for diagnosis and treatment in every case. After Nocardia asteroides was seen on Gram's stain and subsequently identified by culture, appropriate antibiotic therapy was initiated. Both heart transplant patients survived in good neurological condition. We believe that stereotactic aspiration followed by prolonged antibiotic therapy may significantly improve the outcome of patients with nocardial brain abscess.

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

Opportunistic infections are increasingly becoming a problem in cancer patients amongst whom infection with Nocardia species is particularly difficult to detect due to the capricious natural history of the disease. Three cases of Nocardia infection in patients who had undergone splenectomy for haematological malignancy are presented. These cases illustrate the diverse mode of presentation, the natural history and the difficulties in early and accurate diagnosis of Nocardia infection. Despite the difficulties in arriving at the correct diagnosis, these cases highlight the importance of early institution of appropriate antibiotic therapy. Antibiotics should be given in adequate doses to control the initial infection and be maintained for a prolonged period to prevent relapses.

Cutaneous nocardiosis. Case reports and review

Two cases of cutaneous nocardial infection are reported. The Nocardia species are gram-positive, partially acid-fast bacteria. Cutaneous involvement may develop as one of four types: (1) mycetoma, (2) lymphocutaneous (sporotrichoid) infection, (3) superficial skin infection, or (4) systemic disease with cutaneous involvement. A review of each of these types of infection is included, as well as potential clues that may suggest the diagnosis of nocardiosis.

Parenteral trimethoprim/sulfamethoxazole for gram-negative bacillary meningitis

Three adults with gram-negative bacillary meningitis were treated with an intravenous preparation of trimethoprim and sulfamethoxazole. This therapy sterilized the cerebrospinal fluid in each case. The infections occurred as complications of neurosurgery, trauma and chronic otitis media. Serratia marcescens was the causative organism in two patients and Proteus vulgaris in the third. The infecting organism was eradicated within three to 17 days of beginning intravenous trimethoprim/sulfamethoxazole. Followup CSF cultures after completing therapy were sterile. These cases suggest intravenous trimethoprim/sulfamethoxazole may be effective treatment for some cases of gram negative bacillary meningitis.

Synergistic action of trimethoprim and sulfamethoxazole for Nocardia asteroides: efficacious therapy in five patients

Eighteen isolates of Nocardia asteroides were tested for in vitro susceptibility to trimethoprim (TMP) and sulfamethoxazole (SMZ) alone and in various combinations using disc and paper strip diffusion tests. TMP-SMZ showed synergistic action for two-thirds of teh nocardia isolates tested. Five patients with Nocardia pneumonia were treated with TMP-SMZ and all were cured. Four of the patients' isolates were tested and all showed synergistic patterns of inhibition with the spaced disc and paper strip methods. The agar diffusion disc and synergy tests of TMP-SMZ appear to correlate with clinical usefulness when the Nocardia are susceptible with large zones of inhibition around the combination TMP-SMZ disc.