High-frequency intragenomic heterogeneity of the ribosomal DNA intergenic spacer region in Trichophyton violaceum.

The intergenic spacer (IGS) of the rRNA genes was analyzed from the dermatophyte Trichophyton violaceum isolated from cases of tinea capitis in Taiwan and Iran. T. violaceum strains were cultured from different colonies, from single conidial colonies derived by dilution plating, and from micromanipulation of single conidia from clinical samples. A ribosomal DNA probe hybridizing to multiple EcoRI fragments was used to compare restriction fragment length polymorphisms in different T. violaceum isolates. The arthroconidia of T. violaceum that form in vivo during infection were shown to contain a single nucleus by 4',6'-diamidino-2-phenylindole staining. IGS regions from an isolate cultured from a single conidium were amplified, cloned, and sequenced. The results identified that heterogeneity exists between IGS regions within a single T. violaceum genome due to different copy numbers of a 171-bp tandem repeat. This suggests that the IGS of T. violaceum is partially excluded from the concerted evolution of the rRNA gene locus. The heterogeneous character of the IGS regions in T. violaceum contrasts with the closely related dermatophyte Trichophyton rubrum, posing further questions on the phylogeny and the evolution of dermatophyte fungi.

Comparison of CPS ID 3 and CHROMagar Orientation chromogenic agars with standard biplate technique for culture of clinical urine samples.

BACKGROUND AND PURPOSE: Chromogenic agars have been developed to recognize frequently occurring microorganisms directly on primary cultures, thus reducing the daily workload in a clinical microbiology laboratory. We compare two chromogenic agars, CHROMagar Orientation (CO) and CPS ID 3 (CPS3), with routine media (biplate technique using trypticase soy blood agar and eosin methylene blue agar) for the isolation, enumeration and identification of organisms in urinary tract infection (UTI). METHODS: The clinical significance of the urine samples was categorized as probable UTI, possible UTI, no UTI (negative), or contaminated according to the culture result. Discrepancy analysis with the categories of minor error, major error and very major error was used to compare the culture media. RESULTS: Of 1386 urine specimens, the consistencies in clinical significance of CO and CPS3 to routine media were 90.7% and 89.8%, respectively. For the enumeration of microorganisms, 524, 514, and 521 clinically significant isolates were isolated on routine media, CO, and CPS3, respectively. Of the 524 significant isolates on routine media, results for 473 and 474 isolates agreed on CO and CPS3, respectively. Approximately 91.9% of Escherichia coli and 100.0% of Enterococcus spp. could be identified directly on CO media, while 97.5% of E. coli and 94.4% of Enterococcus spp. could be identified on CPS3 media. CONCLUSION: The use of CO and CPS3 as single media is promising for clinical urine culture.