Rapid identification of cutaneous infections by nontubercular mycobacteria by polymerase chain reaction-restriction analysis length polymorphism of the hsp65 gene.

BACKGROUND: Nontubercular mycobacteria (NTM) may cause cutaneous infections which are difficult to interpret due to the variability of the clinical manifestations. This study involved eight patients (four men and four women) with primary cutaneous infections caused by NTM; the skin lesions included dermo-hypodermal abscesses, suppurative granulomas, and papulonodules localized on the legs, arms, hands, and face. The general condition of the patients was relatively good and they were not immunosuppressed. METHODS: All samples were processed with standard methods and the isolates were identified by pattern restriction analysis after polymerase chain reaction (PCR-PCA) amplification of the heat shock protein of 65 kDa. RESULTS: In this way, we were able to identify three Mycobacterium chelonae strains, two Mycobacterium marinum, two Mycobacterium fortuitum, and one Mycobacterium avium. The lesions disappeared in 3 or 4 weeks after treatment with two or more antimicrobials. CONCLUSIONS: For a correct diagnosis of cutaneous infection by NTM, demonstrating the presence of mycobacteria is essential; routinely available techniques lack sensitivity and are extremely tedious; often mycobacteria are not seen after acid-fast stain. We used PCR-PCA to identify mycobacteria grown in liquid media; the time of identification of mycobacteria was shortened relative to conventional methods.

Statistical evaluation of the persistence of acquired hypersensitivity by standardized patch tests.

Numerous studies have focused attention on the influence of various biological and environmental factors on contact hypersensitivity. In order to evaluate the persistence and/or modification of allergic contact sensitivity to a number of common contact sensitizers, the same standardized patch tests were repeated on 174 subjects with contact sensitivity after a time lapse of 5 years (1987-1992). In 18.4% of the cases, 1 or more sensitivities were lost; 28.7% of the patients had a higher number of positive patch tests after 5 years, while the remaining 52.9% of the patients showed no change in the number of positive patch tests. In 88%, the positive allergens were unchanged, whereas in the remaining 12% of the subjects, they showed 1 or more variations. The association between the allergens most often positive was calculated for both the 1st and the 2nd patch test results. Moreover, to evaluate the frequency of an allergen's positivity, we studied the disappearance of old sensitivities and the appearance of new sensitivities by the McNemar test. Cobalt chloride was the only allergen with a significant frequency of new positivities over the period of observation (p < 0.01). Logistic regression analysis was performed to evaluate the possible influence of positive tests to other allergens, and of some clinical findings associated with contact dermatitis, on the sensitivity to cobalt chloride in 1987 and in 1992.