Laboratory identification and clinical characteristics of Streptococcus bovis/Streptococcus equinus complex bacteremia: a retrospective, multicenter study in Hiroshima, Japan

Background Bacteremia due to the Streptococcus bovis/Streptococcus equinus complex (SBSEC) is associated with specific diseases, such as colorectal cancer and infective endocarditis. This study aimed to evaluate the clinical characteristics of SBSEC bacteremia and the accuracy of identification of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and phenotypic identification systems for SBSEC isolates. Methods We analyzed patients with SBSEC bacteremia retrospectively between 2012 and 2019 at three hospitals in Japan. We re-identified each SBSEC isolate using sequencing superoxide dismutase (sodA) analysis, MALDI-TOF MS using the MALDI Biotyper, and phenotypic identification using the VITEK2. Results During the study period, 39 patients with SBSEC bacteremia were identified. S. gallolyticus subsp. pasteurianus (SGSP, n = 29), S. gallolyticus subsp. gallolyticus (SGSG, n = 5), S. lutetiensis (SL, n = 4), and S. infantarius subsp. infantarius (n = 1) were identified using sodA sequencing analysis. Primary bacteremia (36%) was the most common cause of bacteremia, followed by infective endocarditis (26%) and biliary tract infections (23%). Colorectal cancer was associated significantly with SGSG bacteremia, while the sources of bacteremia were similar in each SBSEC subspecies. The MALDI Biotyper was significantly more accurate in identifying the SBSEC isolates at the subspecies level compared to the VITEK2 (92% vs. 67%, P = 0.010). In contrast, there were no significant differences in the rates of correct identification of the SBSEC isolates at the species level between the MALDI Biotyper and the VITEK2 (100% vs. 87%, P = 0.055). Conclusions Bacteremia with SGSG was associated with colorectal cancer, and the sources of bacteremia were similar in each SBSEC subspecies. The MALDI-TOF MS was significantly more accurate in identifying SBSEC isolates at the subspecies level than the phenotypic identification systems. The accurate identification of SBSEC isolates using the MALDI-TOF MS and phenotypic identification systems was sufficient at the species level, but it was insufficient at the subspecies level. Therefore, it may be reasonable for clinicians to perform echocardiographies and colonoscopies in all patients with SBSEC bacteremia.

Genetic characteristics and ploidy trigger the high inducibility of double haploid (DH) inducer in Brassica napus

Background Our recently reported doubled haploid (DH) induction lines e.g., Y3380 and Y3560 are allo-octoploid (AAAACCCC, 2n = 8× ≈ 76), which can induce the maternal parent to produce DH individuals. Whether this induction process is related to the production of aneuploid gametes form male parent and genetic characteristics of the male parent has not been reported yet. Results Somatic chromosome counts of DH inducer parents, female wax-less parent (W1A) and their F1 hybrid individuals revealed the reliability of flow cytometry analysis. Y3560 has normal chromosome behavior in metaphase I and anaphase I, but chromosome division was not synchronized in the tetrad period. Individual phenotypic identification and flow cytometric fluorescence measurement of F1 individual and parents revealed that DH individuals can be distinguished on the basis of waxiness trait. The results of phenotypic identification and flow cytometry can identify the homozygotes or heterozygotes of F1 generation individuals. The data of SNP genotyping coupled with phenotypic waxiness trait revealed that the genetic distance between W1A and F1 homozygotes were smaller as compared to their heterozygotes. It was found that compared with allo-octoploids, aneuploidy from allo-octoploid segregation did not significantly increase the DH induction rate, but reduced male infiltration rate and heterozygous site rate of induced F1 generation. The ploidy, SNP genotyping and flow cytometry results cumulatively shows that DH induction is attributed to the key genes regulation from the parents of Y3560 and Y3380, which significantly increase the induction efficiency as compared to ploidy. Conclusion Based on our findings, we hypothesize that genetic characteristics and aneuploidy play an important role in the induction of DH individuals in Brassca napus, and the induction process has been explored. It provides an important insight for us to locate and clone the genes that regulate the inducibility in the later stage.

RAPID SCREENING OF PHYTOPATHOGENIC Erwinia sp. OF TWO POTATO VARIETIES (SPUNTA AND DESIREE) FROM ALGERIAN AGRICULTURAL FIELDS

Rapid screening of phytopathogenic Erwinia sp. of two potato varieties (Spunta and Desiree) from Algerian agricultural fileds. Isolation, phenotypic identification and in vitro phytopathogenicity screening of Erwinia sp. from agricultural field of two potato varieties (Spunta and Desiree) in Algeria. The current study aims to isolate, identify and screen phytopathogenic isolates of Erwinia sp. causing potato diseases. The techniques presented in this study for isolation and characterization of phytopathogenic Erwinia sp. are conventional methods that are used in this field of research. Seven phytopathogenic bacteria were recovered from potato tubers of two varieties (Spunta and Desiree). The phenotypic identification allowed characterizing typical colonies of Erwinia sp. on two semi-selective media: King’s B and TCC media. Erwinia sp. formed characteristic colonies on King’s B medium that were round, convex and representing creamy color. While, Erwinia sp. also developed specific colonies on TCC medium which were pale purple, circular, convex, even bulging; smooth and mucous. In vitro phytopathogenicity test on potato slices lead to screen the phytopathogenic isolate E5 characterized by highest rotten tissue zone of (2.33 ± 0.29 cm) and (2.33 ± 0.58 cm) toward Spunta and Desiree varieties, respectively. Followed, by isolate E4 characterized by rotten tissue zone of (1.83 ± 0.58 cm) and (2.17 ± 0.29 cm) toward Spunta and Desiree varieties, respectively; compared to their corresponding uninfected controls. The RTZ (Rotten tissue zone) evidently is proportional to the specific pathogenicity of Erwinia sp. isolates and the characteristic sensitivity of various varieties (Spunta and Desiree). Thus, make determining RTZ a rapid screening technique for the selection of the highest phytopathogenic isolates. This investigation provides valuable information for rapid screening (infected potato tuber) and characterization (isolation using semi-selective media) of pathogenic Erwinia sp. engendering potato disease compared to existing methods like infection of leaves or plants; and phytopathogenic Erwinia sp. identification through PCR amplification or in situ hybridation.

Candida duobushaemulonii: An Old But Unreported Pathogen

Candidiasis caused by species of the Candida haemulonii complex (Candida haemulonii and Candida duobushaemulonii) and closely related species, Candida auris and Candida pseudohaemulonii are increasing. These species often show reduced susceptibility to antifungal drugs, such as azoles and amphotericin B or, less frequently, echinocandins. However, conventional phenotypic identification methods are unable to accurately differentiate these species and, therefore, their prevalence may have been underestimated. In this study, 150 isolates that were probably misidentified were reanalyzed using two novel PCR approaches. We found that one isolate previously identified in 1996 as Candida intermedia was C. duobushaemulonii, being one of the oldest isolates of this species described to date. We also found that this isolate had reduced susceptibility to fluconazole, itraconazole, and amphotericin B.

Phenotypic Identification and Antifungal Susceptibility of Two Rhodotorula Species Isolated from Dandruff Samples

Rhodotorula are environmental yeasts originally considered non-pathogenic in nature. However, over the last three decades, different species of this yeast have established themselves as pathogens in humans, causing systemic infections among the immunocompromised population. In this study, Rhodotorula species were isolated from dandruff samples using selective media by observing colony morphology and color. The isolates were later identified via biochemical tests and microscopic examinations. In addition, the sensitivity of the isolates to the three antifungal agents, namely ketoconazole, nystatin and fluconazole were tested by using the disk diffusion technique. On completion of the tests, only two species of Rhodotorula were identified from 35 dandruff samples and designated as R1 and R3. Both isolates displayed sensitivity towards ketoconazole and nystatin. No antifungal sensitivity was documented against fluconazole. This study gave preliminary indication of the presence of Rhodotorula species in dandruff samples, and its sensitivity towards antifungal agents. Dhaka Univ. J. Pharm. Sci. 19(2): 185-190, 2020 (December)