Complete sequence of carbapenem-resistant Ralstonia mannitolilytica clinical isolate co-producing novel class D ß-lactamase OXA-1176 and OXA-1177 in Japan.

In 2020, the Ralstonia mannitolilytica strain JARB-RN-0044 was isolated from a midstream urine sample of an elderly hospitalized patient in Japan and was highly resistant to carbapenem (i.e., imipenem, meropenem, and doripenem). Whole-genome sequencing revealed that the complete genome consists of two replicons, a 3.5-Mb chromosome and a 1.5-Mb large non-chromosomal replicon which has not been reported in R. mannitolilytica, and referred to as the "megaplasmid" in this study based on Cluster of Orthologous Group of proteins functional analysis. The strain JARB-RN-0044 harbored two novel OXA-60 and OXA-22 family class D ß-lactamase genes blaOXA-1176 and blaOXA-1177 on the megaplasmid. Cloning experiments indicated that Escherichia coli recombinant clone expressing blaOXA-1176 gene showed increased minimum inhibitory concentrations (MICs) of imipenem, meropenem, and doripenem, indicating that blaOXA-1176 gene encodes carbapenemase. In contrast, E. coli recombinant clone expressing blaOXA-1177 gene showed increased MICs of piperacillin and cefazolin, but not of carbapenem. Interestingly, the 44.6 kb putative prophage region containing genes encoding phage integrase, terminase, head and tail protein was identified in the downstream region of blaOXA-1176 gene, and comparative analysis with some previously reported R. mannitolilytica isolates revealed that the prophage region was unique to strain JARB-RN-0044. The existence of a highly carbapenem-resistant R. mannitolilytica isolate may raise human health concerns in Japan, where the population is rapidly aging.IMPORTANCERalstonia mannitolilytica is an aerobic non-fermenting Gram-negative rod commonly found in aquatic environments and soil. The bacteria can occasionally cause severe hospital-acquired bloodstream infections in immunocompromised patients and it has been recently recognized as an emerging opportunistic human pathogen. Furthermore, some R. mannitolilytica isolates are resistant to various antimicrobial agents, including ß-lactams and aminoglycosides, making antimicrobial therapy challenging and clinically problematic. However, clinical awareness of this pathogen is limited. To our knowledge, in Japan, there has been only one report of a carbapenem-resistant R. mannitolilytica clinical isolate from urine by Suzuki et al. in 2015. In this study, whole-genome sequencing analysis revealed the presence and genetic context of novel blaOXA-1176 and blaOXA-1177 genes on the 1.5 Mb megaplasmid from highly carbapenem-resistant R. mannitolilytica isolate and characterized the overall distribution of functional genes in the chromosome and megaplasmid. Our findings highlight the importance of further attention to R. mannitolilytica isolate in clinical settings.

Constitutive activation of signal transducers and activators of transcription 3 correlates with cyclin D1 overexpression and may provide a novel prognostic marker in head and neck squamous cell carcinoma.

The precise mechanism responsible for the frequent overexpression of cyclinD1 in human head and neck squamous cell carcinoma (HNSCC) is not known. In view of the fact that signal transducers and activators of transcription 3 (Stat3) is often activated in HNSCC cells, we examined the effects of Stat3 on cyclin D1 expression and cell proliferation in the YCU-H891 HNSCC cell line that displays constitutive activation of Stat3. Expression of a dominant negative Stat3 construct in YCU-H891 cells inhibited proliferation, cyclin D1 promoter activity, and cellular levels of cyclin D1 mRNA and protein. The levels of the antiapoptotic Bcl-2 and Bcl-X(L) proteins were also inhibited. In 51 primary tumor samples from patients with squamous cell carcinoma of the p.o. tongue, there was a significant correlation between increased levels of the activated form of Stat3, phosphorylated-Stat3, and increased levels of cyclin D1 (P < 0.0001). Increased tumor levels of phosphorylated-Stat3 were also associated with lower survival rates (P < 0.01). This study provides the first evidence that in HNSCC, constitutive activation of Stat3 plays a causative role in overexpression of cyclin D1, and in clinical studies, Stat3 activation may provide a novel prognostic factor. Furthermore, agents that target Stat3 may be useful in the treatment of HNSCC.

Serum squamous cell carcinoma antigen is a useful biologic marker in patients with inverted papillomas of the sinonasal tract.

BACKGROUND: Inverted papilloma (IP) is a frequent benign sinonasal tumor that is characterized histologically by squamous metaplasia, epithelial acanthosis, and hyperplasia of the nasal epithelium. Because of its high recurrence rate and malignant transformation potential, careful long-term follow up is necessary. METHODS: The purpose of the current report was to study the expression of squamous cell carcinoma (SCC) antigen in sinonasal IPs and to evaluate the usefulness of SCC antigen as a biologic marker for the follow-up of patients with sinonasal IP. The expression of SCCA1 in three sinonasal IP cases, three sinonasal SCC cases, and cases of normal nasal epithelium were examined by Western blot analysis, and the SCCA1 expression pattern in 31 IP specimens and 4 carcinoma in IP specimens were evaluated immunohistochemically. The serum levels of SCC antigen in 11 patients with sinonasal IP also were analyzed. RESULTS: SCCA1 was overexpressed in all three sinonasal IP tissues compared with sinonasal SCC tissues or normal nasal epithelium. SCCA1 cytoplasmic immunoreactivity was detected in the suprabasal epidermal keratinocytes of all 31 sinonasal IP cases. In the four carcinoma in IP specimens, SCCA1 expression in the papillomatous lesion was more intense than in the cancerous lesion. The serum SCC antigen level was high in 10 of 11 patients with IP (91%) and significantly decreased after surgical resection of the tumors. CONCLUSIONS: The results of the current study indicate that SCCA1 frequently is overexpressed and may play a biologic role in the development of sinonasal IPs. Serum SCC antigen may be a useful biologic marker in patients with sinonasal IP.