Klebsiella pneumoniae Carbapenemase (KPC)-Producing K. pneumoniae at a Single Institution: Insights into Endemicity from Whole-Genome Sequencing

The global emergence of Klebsiella pneumoniae carbapenemase-producing K. pneumoniae (KPC-Kp) multilocus sequence type ST258 is widely recognized. Less is known about the molecular and epidemiological details of non-ST258 K. pneumoniae in the setting of an outbreak mediated by an endemic plasmid. We describe the interplay of bla_KPC plasmids and K. pneumoniae strains and their relationship to the location of acquisition in a U.S. health care institution. Whole-genome sequencing (WGS) analysis was applied to KPC-Kp clinical isolates collected from a single institution over 5 years following the introduction of bla_KPC in August 2007, as well as two plasmid transformants. KPC-Kp from 37 patients yielded 16 distinct sequence types (STs). Two novel conjugative bla_KPC plasmids (pKPC_UVA01 and pKPC_UVA02), carried by the hospital index case, accounted for the presence of bla_KPC in 21/37 (57%) subsequent cases. Thirteen (35%) isolates represented an emergent lineage, ST941, which contained pKPC_UVA01 in 5/13 (38%) and pKPC_UVA02 in 6/13 (46%) cases. Seven (19%) isolates were the epidemic KPC-Kp strain, ST258, mostly imported from elsewhere and not carrying pKPC_UVA01 or pKPC_UVA02. Using WGS-based analysis of clinical isolates and plasmid transformants, we demonstrate the unexpected dispersal of bla_KPC to many non-ST258 lineages in a hospital through spread of at least two novel bla_KPC plasmids. In contrast, ST258 KPC-Kp was imported into the institution on numerous occasions, with other bla_KPC plasmid vectors and without sustained transmission. Instead, a newly recognized KPC-Kp strain, ST941, became associated with both novel bla_KPC plasmids and spread locally, making it a future candidate for clinical persistence and dissemination.     

Reconstruction of Lateral Skull Base Defects with Radial Forearm Free Flaps: The Double-Layer Technique

Introduction The radial forearm flap has fallen out of favor in lateral skull base reconstruction in recent literature. However, especially when used in a double layer, a radial forearm may be able to provide the thickness of a large flap while taking advantage of the pliability for which the flap is renowned. Objective To report the results of the double-layer technique of radial forearm free flap reconstruction of lateral temporal bone defects. Design A retrospective chart review. Setting A tertiary care institution. Participants All consecutive patients who underwent lateral temporal bone resections and were reconstructed with free flaps from 2006 to 2012. Major Outcome Measures Flap success rate, complications, and rate of revision surgery. Results A total of 17 patients were identified with free flap reconstruction of the lateral skull base. Seven received reconstruction with a double-layer radial forearm flap. Reconstruction-related complications in this group included one case of facial cellulitis. The flap success rate was 100%. These results were comparable with patients who had other flaps. Conclusions The radial forearm free flap may be an effective reconstruction option for lateral temporal bone defects especially when used in the double-layer technique.     

Incidence and Survival Patterns of Sinonasal Undifferentiated Carcinoma in the United States

Objective To determine trends in sinonasal undifferentiated carcinoma (SNUC) survival patterns in the United States. Design Retrospective review of national database. Participants All cases of SNUC in the National Cancer Institute''s Surveillance Epidemiology and End Results program from 1973 to 2010 were examined. Main Outcome Measures Age-adjusted incidence and survival rates were calculated and stratified by demographic information and treatment modality. Cohort analysis was performed to analyze survival patterns over time. Results A total of 318 SNUC cases were identified. Age-adjusted incidence rate (IR) was 0.02 per 100,000. Incidence was greater in males (IR: 0.03) than females (IR: 0.01; p = 0.03). Overall 5- and 10-year relative survival rate was 34.9% and 31.3%, respectively. Overall median survival was 22.1 months. Median survival following surgery combined with radiation was 41.9 months. Five-year relative survival rate following surgery, radiation, or surgery combined with radiation was 38.7%, 36.0%, and 39.1%, respectively. Median survival from 1973–1986 and 1987–2010 was 14.5 and 23.5 months, respectively. Conclusions This study provides new data regarding survival patterns of SNUC in the United States, confirming survival benefit with surgery and radiation as well as identifying a trend toward improved survival in recent decades.     

Functional characterization of BRCA1 gene variants by mini-gene splicing assay

Mutational screening of the breast cancer susceptibility gene BRCA1 leads to the identification of numerous pathogenic variants such as frameshift and nonsense variants, as well as large genomic rearrangements. The screening moreover identifies a large number of variants, for example, missense, silent, and intron variants, which are classified as variants of unknown clinical significance owing to the lack of causal evidence. Variants of unknown clinical significance can potentially have an impact on splicing and therefore functional examinations are warranted to classify whether these variants are pathogenic or benign. Here we validate a mini-gene splicing assay by comparing the results of 24 variants with previously published data from RT-PCR analysis on RNA from blood samples/lymphoblastoid cell lines. The analysis showed an overall concordance of 100%. In addition, we investigated 13 BRCA1 variants of unknown clinical significance or putative variants affecting splicing by in silico analysis and mini-gene splicing assay. Both the in silico analysis and mini-gene splicing assay classified six BRCA1 variants as pathogenic (c.80+1G>A, c.132C>T (p.=), c.213−1G>A, c.670+1delG, c.4185+1G>A, and c.5075−1G>C), whereas six BRCA1 variants were classified as neutral (c.-19-22_-19-21dupAT, c.302−15C>G, c.547+14delG, c.4676−20A>G, c.4987−21G>T, and c.5278−14C>G) and one BRCA1 variant remained unclassified (c.670+16G>A). In conclusion, our study emphasizes that in silico analysis and mini-gene splicing assays are important for the classification of variants, especially if no RNA is available from the patient. This knowledge is crucial for proper genetic counseling of patients and their family members.     

Transcatheter Aortic Valve Implantation in the Elderly: Who to Refer?

In recent years, experience with transcatheter aortic valve implantation has led to improved outcomes in elderly patients with severe aortic stenosis (AS) who may not have previously been considered for intervention. These patients are often frail with significant comorbid conditions.