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

Bacterial Infections

In Osier’s time, bacterial pneumonia was a dreaded event, so important that he borrowed John Bunyan’s characterization of tuberculosis and anointed the pneumococcus, as the prime pathogen, “Captain of the men of death.”1 One hundred years later much has changed, but much remains the same. Pneumonia is now the sixth most common cause of death and the most common lethal infection in the United States. Hospital-acquired pneumonia is now the second most common nosocomial infection.2 It was documented as a complication in 0.6% of patients in a national surveillance study,3 and has been reported in as many as 20% of patients in critical care units.4 Furthermore, it is the leading cause of death among nosocomial infections.5 Leu and colleagues6 were able to associate one third of the mortality in patients with nosocomial pneumonia to the infection itself. The increase in hospital stay, which averaged 7 days, was statistically significant. It has been estimated that nosocomial pneumonia produces costs in excess of $500 million each year in the United States, largely related to the increased length of hospital stay.

Two cases of multidrug-resistant Nocardia farcinica infection in immunosuppressed patients and implications for empiric therapy

Presented here are two cases of multidrug-resistant Nocardia farcinica infection that occurred in immunocompromised patients. One of the patients developed the infection despite being on trimethoprim/sulfamethoxazole prophylaxis for Pneumocystis jiroveci. These cases demonstrate the propensity of Nocardia spp. to cause disseminated disease and to develop resistance to multiple antimicrobial agents used in the initial treatment of serious Nocardia infection. These factors lead to the conclusion that empiric monotherapy with trimethoprim/sulfamethoxazole may not be sufficient. Treatment with a combination regimen of imipenem and amikacin may be a more promising initial therapy.

Case report: Nocardia osteomyelitis

Osteomyelitis is an unusual manifestation of infection with Nocardia spp, and most cases result from direct extension from a primary lung or cutaneous lesion. The authors report what they believe to be the first case of Nocardia vertebral osteomyelitis occurring postoperatively, and review the literature on the 19 previously reported cases of Nocardia osteomyelitis due to hematogenous dissemination or direct inoculation, excluding those occurring from direct extension of a mycetoma or primary lung infection.

A case of testicular nocardiosis and literature review

A case of epididymo-orchitis due to Nocardia asteroides in a liver transplant recipient is reported. Nocardiosis is an extremely rare cause of epididymo-orchitis. Four other cases published in the English language medical literature are reviewed. All patients were immunocompromised, and other organs were affected simultaneously. Clinically the infection presented as a painful enlargement of the testicle with few inflammatory signs. Mortality was high (3/5), and in the two survivors long-term sulfonamide therapy was combined with orchiectomy. Nocardiosis should be considered in the diagnosis of epididymo-orchitis in the immunocompromised host.

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.

Septic arthritis due to Nocardia caviae

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Nanocolloid scintigraphy for rheumatic diseases of the hands

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Trimethoprim-sulfamethoxazole and other sulfonamides

Trimethoprim-sulfamethoxazole continues to be a useful antibiotic for common outpatient problems such as urinary tract infections, prostatitis, acute exacerbations of chronic bronchitis, and acute otitis media as well as for serious infections of the hospitalized patient including Pneumocystis carinii pneumonia, acute pyelonephritis, and some forms of gram negative meningitis. The other sulfonamides have a limited role.