Nocardiosis at the Turn of the Century

Abstract

Nocardia species is an uncommon pathogen that affects both immunosuppressed and immunocompetent patients. The clinical and microbiologic spectrum of nocardiosis has changed recently due to the widespread use of cotrimoxazole prophylaxis, the emergence of new types of immunosuppressed patients, and the improved identification of isolates using molecular techniques. Nocardia asteroides was traditionally considered the predominant organism, and prophylaxis with cotrimoxazole was considered almost universally protective. We conducted the current study to determine the incidence of nocardiosis and its microbiologic and clinical characteristics in a general hospital over the last 12 years. We reviewed the clinical records of all patients in whom Nocardia species was isolated from clinical specimens between 1995 and 2006. Nocardia isolates were identified by standard procedures and by 5' end 16S rRNA gene polymerase chain reaction (PCR) and sequencing. Susceptibility to cotrimoxazole, minocycline, imipenem, linezolid, and amikacin was determined by the broth microdilution method following the guidelines of the Clinical and Laboratory Standards Institute.The incidence of Nocardia infections did not increase significantly during the study period (0.39/100,000 inhabitants in 1995-1998 and 0.55/100,000 inhabitants in 2003-2006). Nocardia was recovered from 43 patients. Six were considered to be colonized. The colonizing species were N. farcinica, N. nova, and N. asteroides. All colonized patients had severe underlying pulmonary conditions and were treated with antimicrobials (6 patients) or corticosteroids (4 patients). Invasive nocardiosis was diagnosed in 37 patients (86.5% were men, and their mean age was 55.8 +/- 17.3 yr). The most common underlying condition in our institution was human immunodeficiency virus (HIV) infection (10 patients; 27%), followed by chronic obstructive pulmonary disease (8 patients; 21.6%), autoimmune diseases (8 patients; 21.6%), solid organ transplantation (7 patients; 18.9%), and cancer (4 patients; 10.8%). The most important risk factor for nocardiosis was corticosteroid administration (23 patients; 62.2%). Nocardiosis affected the lungs in 26 cases (70.3%), the skin in 3 cases (8.1%), and the central nervous system in 2 cases (5.4%). It was disseminated in 5 cases (13.5%) and caused otomastoiditis in 1 (2.7%). The species identified were N. cyriacigeorgica (32.4%), N. farcinica (24.3%), N. otitidiscaviarum (10.8%), N. veterana (8.1%), N. nova (5.4%), N. abscessus (5.4%), N. asiatica (2.7%), N. beijingensis (2.7%), N. brasiliensis (2.7%), N. carnea (2.7%), and Nocardia species (2.7%).Linezolid and amikacin were uniformly active against all the isolates, whereas 29.7% of isolates showed intermediate susceptibility to minocycline (minimum inhibitory concentration = 2 mg/L), 10.8% were resistant to cotrimoxazole, and 5.4% were resistant to imipenem. Nocardiosis occurred while the patients were on cotrimoxazole prophylaxis in 8 cases (21.6%). The strains isolated from these patients were suscept...

Diversity and frequency of Nocardia spp. in the soil of Isfahan province, Iran

“…In our study, Nocardia prevalence in soil was 16.4%. The frequency of pathogenic Nocardia species acquired from soil samples in different regions of the world has been reported to be 5%-50% [27][28][29][30] .…”

“…Increase in the infections caused by these organisms, with different clinical forms of systemic and disseminated forms of nocardiosis in transplant recipients, tuberculosis, liver cirrhosis, cancer, diabetes, AIDS and patients under treatment with immunosuppressive drugs and broad spectrum antibiotics in the world, reveals more importance of isolation and identification of these agents [2,[11][12][13][14][15][16][17][18][19][20][21][22][23][24] . Various studies have shown that identification and isolation of these agents in soil of different areas help to diagnose nocardiosis [1] .…”

Molecular identification of clinical Nocardia isolates from India

“…of which many are finally identified as Actinomycetes other than Nocardia. The lung is the major organ primarily affected, accounting for 60-70 % of all human nocardiosis (Minero et al, 2009). Mortality due to nocardiosis ranges from 40 to 80 % depending on the immune status of the patient and intervention therapy (Knollmann et al, 2000;Martínez Tomás et al, 2007;Minero et al, 2009;Peleg et al, 2007;Zeidman et al, 1995).…”

HIV-Associated Bacterial Pneumonia

“…Nocardia is an aerobic actinomycete that can cause infections, including pneumonia, usually in association with immunosuppression, including HIV infection [67,68]. The clinical course is often chronic, although dissemination can occur and be associated with a high mortality [68].…”