Katsukiyo Yazawa

Nocardial infections in Japan from 1992 to 2001, including the first report of infection by Nocardia transvalensis

In the period from 1992 to 2001, 303 cases of nocardioses were diagnosed in Japan, with the corresponding etiological agents isolated and characterized. Taxonomic analyses of these 303 strains showed that most nocardial infections were caused by members of the Nocardia asteroides group (72.3%). Speciation showed that 72 strains were N. asteroides, 31 strains were N. cyriacigeorgica, 2 strains were N. beijingensis, 81 strains were N. farcinica, and 33 strains were N. nova. Sixty-six strains of N. brasiliensis were the next most prevalent species of the total Nocardia isolates, followed by 14 strains of N. otitidiscaviarum. Infections by N. transvalensis(3 strains) and N. pseudobrasiliensis(1 strain) were also confirmed. The infections due to N. transvalensis, N. cyriacigeorgica, and N. beijingensis were the first reported in Japan. The most common factor that predisposed individuals to nocardial infection in Japan was therapy by immunosuppressive agents (22.4%), including SLE therapy (3.6%), followed by cancer (6.6%), diabetes (3.6%) and AIDS (2.0%). Nocardial infections occurred more commonly in the elderly, with most of the patients between the ages of 61 and 80 years of age. No significant difference regarding infectivity levels between the sexes was observed.

Molecular Characterization of New Clinical Isolates of Candida albicans and C. dubliniensis in Japan: Analysis Reveals a New Genotype of C. albicans with Group I Intron

ABSTRACT The genetic diversity of recent clinical isolates of Candida albicans in Japan was studied on the basis of amplified DNA band lengths determined with a specific PCR primer reported to have been designed to span a transposable intron region in the 25S rRNA gene. Our analyses of 301 clinical isolates of C. albicans showed that they could be classified into five genotypes: genotype A (172 isolates), genotype B (66 isolates), genotype C (56 isolates), genotype D (C. dubliniensis; 5 isolates), and a new genotype (designated genotype E; 2 isolates). The new genotype E was characterized to have a group I intron-like sequence, which is longer than hitherto reported ones and which has a nucleotide sequence length of 962 bp. Our analysis of the 962-bp sequence indicated that it is composed of an intron similar to that ofC. dubliniensis of 621 bp with a 341-bp insertion. Analysis of the sequence of the internal transcribed spacer (ITS) region of the genotype E strain showed that its sequence is identical to those of strains of other genotypes, with only a few base substitution differences. Throughout the study, the possible horizontal transfer of the group I intron between C. dubliniensis and C. albicans was suggested. A high degree of correlation between the presence of a group I intron inC. albicans genotype E and susceptibility to the antifungal agent flucytosine was observed. The five isolates ofC. dubliniensis examined in the present study showed genetic diversity when they were compared by randomly amplified polymorphic DNA fingerprinting pattern analysis, and this diversity was also confirmed by the analysis of ITS region sequences.

Ribosylation by mycobacterial strains as a new mechanism of rifampin inactivation.

Several fast-growing Mycobacterium strains were found to inactivate rifampin. Two inactivated compounds (RIP-Ma and RIP-Mb) produced by these organisms were different from previously reported derivatives, i.e., phosphorylated or glucosylated derivatives, of the antibiotic. The structures of RIP-Ma and RIP-Mb were determined to be those of 3-formyl-23-[O-(alpha-D-ribofuranosyl)]rifamycin SV and 23-[O-(alpha-D-ribofuranosyl)]rifampin, respectively. To our knowledge, this is the first known example of ribosylation as a mechanism of antibiotic inactivation.

Serotyping of Cryptococcus neoformans strains isolated from clinical specimens in Thailand and their susceptibility to various antifungal agents

One hundred and thirty-nine strains of Cryptococcus neoformans were isolated in Thailand from clinical specimens including 97 AIDS patients: 67 from Northern, 48 from Central, 17 from Northeastern and 7 from Southern regional hospitals. Six out of the 139 strains were serotype B and the remaining 133 were A. There was no correlation between serotypes and regional distribution. To our knowledge, this is the first report of serotyping studies on C. neoformans in Thailand. Studies on random amplified polymorphic DNA (RAPD) analysis showed that this method is useful for the differentiation of C. neoformans var. gattii (serotypes B and C) and C. neoformans var. neoformans (serotypes A and D). They also indicated that Thai isolates of C. neoformans var. gattii (serotype B) were a homogeneous group on the basis of their genotypes. Antifungal susceptibility tests using 5 antifungal agents including amphotericin B, fluconazole, flucytosine, itraconazole and micronazole against 50 selected strains of C. neoformans showed that they were sensitive to all of the antifungal agents tested except for one strain that was resistant to flucytosine.

Inactivation of rifampin by Nocardia brasiliensis.

Rifampin was glycosylated by a pathogenic species of Nocardia, i.e., Nocardia brasiliensis. The structures of two glycosylated compounds (RIP-1 and RIP-2) isolated from the culture broth of the bacterium were determined to be 3-formyl-23-(O-[beta-D-glucopyranosyl])rifamycin SV and 23-(O-[beta-D-glucopyranosyl])rifampin, respectively. Both compounds lacked antimicrobial activity against other gram-positive bacteria as well as the Nocardia species.

Nocardia arthritidis sp. nov., a New Pathogen Isolated from a Patient with Rheumatoid Arthritis in Japan

ABSTRACT Two different bacterial strains with different drug susceptibilities were isolated from the sputum and an inflammatory discharge from a swelling in the left thigh of a patient with rheumatoid arthritis. Both bacterial strains were provisionally assigned to the genus Nocardia on the basis of their morphological and chemotaxonomic characteristics and were further studied in order to establish their taxonomic status. One strain (IFM 10034) was identified as Nocardia farcinica on the basis of its physiological characteristics. The other strain, which was designated Nocardia sp. strain IFM 10035T, revealed a unique pattern of phenotypic properties that distinguished it from other representatives of established Nocardia species. Comparative 16S rRNA gene sequence studies of Nocardia sp. strain IFM 10035T also showed that the bacterium was closely related to the species Nocardia beijingensis. Determination of DNA-DNA relatedness, however, indicated that Nocardia sp. strain IFM 10035T could be delineated from N. beijingensis. The genotypic and phenotypic data combined indicated that the bacterium merits description as a new Nocardia species. The name proposed for the new species is Nocardia arthritidis sp. nov., the type strain being IFM 10035T (NBRC 100137T, JCM 12120T, DSM44731T). The present study suggests that Nocardia infections can be caused by multiple species of the bacterium.

Pathogenic Nocardia isolated from clinical specimens including those of AIDS patients in Thailand.

Forty strains of nocardioform microorganisms were isolated as clinical specimens including several from AIDS patients in Thailand. Among them, 37 strains were found to belong to the genusNocardia. Our identification studies revealed that most of the strains(25 strains) belong to theN. asteroides group, i.e.,N. asteroides sensu stricto andN. farcinica. Three strains were identified asN. otitidiscaviarum and two strainsN. brasiliensis. In addition, 7 strains of rare pathogenicN. transvalensis were also isolated.

Different Rifampicin Inactivation Mechanisms in Nocardia and Related Taxa

Mycolic acid‐containing bacteria inactivate rifampicin in a variety of ways such as glucosylation, ribosylation, phosphorylation and decolorization. These inactivations were found to be a species‐specific phenomena in Nocardia and related taxa. Gordona, Tsukamurella and fast‐growing Mycobacterium modified rifampicin by ribosylation of the 23‐OH group of the antibiotic. Such ribosylation was not observed in Rhodococcus and Corynebacterium, but phosphorylation of the 21‐OH group of rifampicin was observed in one strain of Rhodococcus. Nocardia modified the antibiotic by glucosylation (23‐OH group) and phosphorylation, but ribosylation was not observed.

Directed biosynthesis of new saframycin derivatives with resting cells of Streptomyces lavendulae.

Saframycin A is an antitumor antibiotic produced by Streptomyces lavendulae 314 which falls into the category of the N-heterocyclic quinone group. Biosynthetically the quinone ring is derived from two tyrosine molecules which condense to generate the basic ring system of saframycin A. The side chain also has been found to derive from two amino acids, i.e., glycine and alanine. Supplementation by various amino acid analogs of the side chain produced three new saframycin derivatives with a replaced side chain. These three saframycins, designated Yd-1, Yd-2, and Y3, contained 2-amino-n-butyric acid, glycine, and alanine residues, respectively. in place of the normal N-terminal pyruvic acid in the side chain of saframycin A. Feeding experiments with 13C-labeled dipeptide indicated that the amino acids are probably incorporated in the side chain as a dipeptide unit. It was also found that saframycin A is produced from saframycin Y3 by an enzymatic deamination reaction. Based on these results, saframycin biosynthesis in S. lavendulae is discussed.

Characterization of clinical isolates of pathogenic Nocardia strains and related actinomycetes in Thailand from 1996 to 2003

In Thailand from 1996 to 2003, 171 strains of pathogenic aerobic actinomycetes from clinical specimens were isolated. Of those strains, 134 were mycolic acid containing actinomycetes, including 96 strains of Nocardia species. Others included 10 strains of Gordonia, 14 strains of Rhodococcus, and 22 strains of Mycobacterium. One strain each of the genera Tsukamurella and Corynebacterium were also isolated. Also identified were 27 strains of non-mycolic acid containing actinomycetes. Our identification studies of 96 strains of Nocardia species showed that significant pathogens in Thailand were N. beijingensis (18 strains), N. cyriacigeorgica (13 strains), and N. farcinica (34 strains); the most prevalent species was N. farcinica (35.4%). We also isolated four strains of N. asiatica, five strains of N. asteroides sensu stricto, four strains of N. nova, seven strains of N. otitidiscaviarum, eight strains of N. transvalensis, and two strains of N. pseudobrasiliensis.