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

Abstract

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.

Nocardiosis in the Tropical Northern Territory of Australia, 1997–2014

“…Our study accords with previous reports of high mortality (31%–40%) and high rates of ICU admission in unrestricted studies of pulmonary and disseminated nocardiosis [10, 19, 26–28]. Severe disease was common, and fulminant presentations were seen in both immunocompetent and immunocompromised individuals.…”

“…In 13% of cases (8 of 61), hazardous alcohol use was the only reported predisposing factor for nocardiosis. These findings support previous studies that have suggested (1) an association between hazardous alcohol use and nocardiosis [19, 21–23], (2) that alcohol abuse may be a predisposing factor for dissemination of Nocardia to the CNS [21, 22, 24], and (3) that alcohol may be an important cofactor in predisposition to Nocardia infection due to its effect on macrophage function [25]. …”

“…Pulmonary nocardiosis is described as the most common clinical presentation of Nocardia infection [4], and 82% of our cohort had pulmonary involvement. Fifteen percent of patients in our series had disseminated disease, slightly higher than the 6%–13% seen in other unrestricted case series [7, 18, 19] but lower than the 20%–21% reported in highly immunosuppressed populations such as solid organ transplant patients [5, 20]. The overall proportion of immunocompromised hosts in our population (36%) was lower than that reported in a previous review of the Nocardia literature [2].…”

“…One third of those with pulmonary and disseminated nocardiosis were admitted to ICU, and 1-year mortality was 38%. It is worth noting that there was a wide range of clinical presentations among immunocompetent hosts, including disseminated disease, as has also been reported previously in Australia [19, 21, 22]. …”

Central nervous system nocardiosis in Queensland

“…[5,32–34] A previous study of nocardiosis in Queensland was published in 1992 and included 102 isolates from a range of clinical sites. [35] Of these, 45 isolates were classified as N asteroides . Given that this publication predates the routine use of molecular diagnostics, it is likely that a different range of species would be identified should the same isolates be tested today.…”