Diagnosis of cutaneous tuberculosis in biopsy specimens by PCR and southern blotting.

Abstract

Aims-To evaluate the use of a gene amplification and hybridisation method for detecting mycobacterial nucleic acid as a possible diagnostic method for cutaneous tuberculosis infection. Methods-Biopsy specimens from 20 patients with various skin conditions of possible tuberculous aetiology were studied. Six patients had ulcerative nodules, seven lupiform lesions, two non-necrotic granulomas, one scrofulous lichen, one impetigo, one erythematosus lesions, one warty lesions, and one suspected tuberculous lipoma. Biopsy specimens were stained using Ziehl-Neelsen stain and cultured in Lowenstein-Jensen medium. DNA was extracted and then amplified by PCR using primers specific for the Mycobacterium tuberculosis complex. Specificity was confirmed by Southern blotting. Results-Of the specimens, 30% were positive for mycobacteria on staining with Ziehl-Neelsen stain, 60% were culture positive and 85% PCR positive. Only 35.2% of specimens were positive with all three techniques. A further 32.5% were both culture and PCR positive. All PCR negative samples were also negative when cultured or stained with Ziehl-Neelsen stain. Of the PCR positive specimens, 29.4% were negative when cultured or stained.Conclusions-PCR, using suitable primers, is an efficient and sensitive method for the diagnosis of cutaneous tuberculosis.

Incidence of various clinico-morphological variants of cutaneous tuberculosis and HIV concurrence: a study from the Indian subcontinent

“…They were confirmed by rapid tests. Viswanathan et al,15 reported a similar incidence of 13.7% in their study, which was similar to that reported by Quiros et al (20%) 16. While TB prevalence has remained stable, the incidence continues to rise, especially in developing countries.…”

Detection of mycobacterial DNA in papulonecrotic tuberculid lesions by polymerase chain reaction

“…Two sections from each biopsy specimen were treated and submitted for PCR amplification as previously described (12,13). Briefly, after xilene treatment and proteolitic digestion in 200 µl of buffer, 20 µl of samples were incubated in a PCR buffer (10 nmol (5′-TGG-TCC-GGT-TCA-TAC-TCG-GGC-TGG-3′) primers make up to 60 µl of total volume for 5 minutes at 95°C (denaturation) and subjected to PCR amplification for 40 cycles of 94°C and 70°C (1 minute at each temperature).…”

“…Briefly, samples were transferred to Hyband N + nylon fillers (Amersham, Little Chalfont, UK) incubated with 5 × SSC, 5 × Denhardt's solution, 0,5% of SDS, and 100 ngr/ml denatured salmon sperm DNA for one hr at 58°C, them hybridized for 18 hr at 58°C with a p32 5′-end labelled internal probe as previously described (14). All chemical reagents were purchased from Sigma Diagnostics (St. Louis, MO).…”

Scrofuloderma induced by surgical drainage in a joint tuberculosis

“…A study showed PCR to be more sensitive than Ziehl-Nielsen staining (85% vs 30%), and than culture ( 85% vs 60%). PCR showed also to be more specific since all PCR negative samples were also negative when culture or stained by Ziehl-Nielsen [12]. Therefore modern tests to detect tuberculosis, such as genetic detection by means of PCR, currently allow us to obtain an early and precise diagnosis and to ensure an early oriented medical treatment.…”