Ten Year Review of Pulmonary Nocardiosis: A Series of 55 Cases

Introduction

Nocardiosis is a rare opportunistic bacterial infection usually seen in immunosuppressed patients. It is caused by gram-positive, aerobic actinomycetes of the Nocardia genus. The most common site of infection is lungs; but it may affect other organs or even disseminate into blood.

Methods

In this a 10-year retrospective review, all diagnosed cases of Pulmonary Nocardiosis in a tertiary care hospital were included. The clinical and radiological characteristics, course of complications and lifesaving interventions, and disease outcome were evaluated.

Results

Among the 55 identified cases, most common risk factor was chronic steroid therapy (n=38; 69.1%). Among respiratory diseases, chronic obstructive pulmonary disease (n=13; 23.6%) and tuberculosis (n=12; 21.8%) were the most common. On chest radiograph, pleural effusion (n=23; 41.8%) and consolidation (n=22; 40.0%) were the common findings. Complications were observed in 32 (58.2%) patients with septicemia and respiratory failure being the most common (n=15; 46.8% in each). Dissemination occurred in 10 (31.2%) patients. The mortality rate of Nocardia is 34.5% (n=19).

Conclusion

The disease burden of Nocardia is underestimated by clinicians and researchers. Pulmonary Nocardia should always be a differential diagnosis of signs of lower respiratory tract infection and must be excluded in patients not responding to treatment of chronic obstructive pulmonary disease (COPD) and pulmonary tuberculosis. Early recognition and individualized management plan can ensure successful recovery.

Plasma level of histamine in aspirin-sensitive urticaria

Twelve patients with a history of aspirin-induced urticaria and/or angioedema were studied before and after the provocation of symptoms with aspirin. The resting plasma histamine levels in these patients (0.95 +/- 0.25 ng/mL) were significantly higher than in 30 control subjects (0.21 +/- 0.02 ng/mL) (P less than .0005) and nine patients with non-aspirin-sensitive urticaria (0.27 +/- 0.06 ng/mL) (P less than .01). The plasma histamine levels fell significantly at the time of adverse reactions to aspirin (P less than .01). The high resting histamine levels, like the high venous prostaglandin F2 alpha levels that we have previously reported in the same group of patients and the high plasma histamine levels we have found in aspirin-sensitive asthmatics suggest an abnormality of mediator release in aspirin-sensitive patients.

Plasma esterase activity in patients with aspirin-sensitive asthma or urticaria

Plasma aspirin esterase activity and cholinesterase activity were reduced in patients with aspirin sensitive asthma and aspirin sensitive urticaria compared to asthmatic and dermatological controls. Phenylacetate (non specific) esterase activities, were however unaltered in these patients. The reason for the lower activity is uncertain but it does not appear to be due to genetically determined lower cholinesterase or due to the avoidance of aspirin by sensitive patients. A low aspirin esterase activity may be a contributory factor in precipitating these aspirin sensitive reactions.

Clinical and biochemical aspects of "aspirin-sensitivity"

Progressively increasing doses of aspirin (acetylsalicylic acid--ASA) were tolerated by 14 out of 15 patients with confirmed aspirin-sensitive urticaria and in 7 out of 9 patients with aspirin-sensitive asthma. Blood levels of histamine and prostaglandin (PG) F2 alpha were significantly raised in these patients before ASA administration. PGF2 alpha levels fell to within the normal range after challenge doses of ASA which were sufficient to cause symptoms. Skin prick testing with histamine and codeine phosphate did not show evidence of abnormal tissue reactivity or mast cell reactivity. A wider spectrum of mediators will need to be considered if the mechanism of symptom production is to be understood.

Effect of aspirin in "aspirin sensitive" patients

Eighteen patients with a history of urticaria or asthma, or both, induced by aspirin were studied before and after provocation of symptoms with aspirin. The plasma prostaglandin F2 alpha concentration, which was characteristically raised before challenge, fell significantly at the time of adverse reactions. Repeated administration of aspirin up to a dose of 650 mg daily induced tolerance in most of the patients, and several developed bronchodilator responses to aspirin. Although median total IgE concentrations may be raised in patients with aspirin sensitivity, it appears likely that pharmacological rather than immunological mechanisms are chiefly responsible for the phenomena of aspirin sensitivity and desensitisation.

Specific desensitization in 'aspirin-sensitive' urticaria; plasma prostaglandin levels and clinical manifestations

Six out of eight patients with a history of aspirin-provoked urticaria/angioedema responded with adverse reactions, including urticaria and bronchospasm, to provoking doses of oral aspirin from 30-515 mg. The other two patients did not react to 1.2 g of aspirin on three occasions. Five of the six patients who had reacted became desensitized after their initial aspirin reaction, tolerating 650 mg on the second day. They then took 650 mg day-1 of aspirin for three weeks, during which time the ingestion of foods which had previously caused a variety of moderate or severe reactions caused no symptoms. The resting plasma PGF2 alpha in ten 'aspirin-sensitive' urticaria patients (24.89 +/- 2.79 pg m-1) was significantly higher than the levels in ten normal subjects (6.75 +/- 1.1 pg ml-1) (P less than 0.01). In the patient group the lowest levels of PGF2 alpha were found in the two patients who subsequently did not experience a positive reaction after aspirin provocation. The PGF2 alpha/PGE2 ratio in 'aspirin-sensitive' urticaria patients (1.83 +/- 0.026) was significantly higher than that in normal subjects (0.63 +/- 0.14) (P less than 0.01).