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The aim of this study is to determine the frequency of virulence genes in high biofilm formation bla KPC-2 producing Klebsiella pneumoniae strains collected over a period of two years. A total of 43 non-repetitive high biofilm bla KPC-2 producing isolates were screened from 429 strains. The MIC of carbapenems (imipenem and meropenem) ranged from 4 to 32 μg/ml. The OD595 value of the biofilm ranged from 0.56 to 2.56. The K1, K2, K5, K20, K54, K57 genotypes, MLST and virulence factors, including entB, ybtS, mrkD, fimH, rmpA, allS, iutA, kfu, wcaG, aerobaction, fecIRA, shiF, magA and pagO gene, were determined by PCR. The results showed that, among the 43 isolates, 5 of 43 were K1 type, 25 of 43 were K2 type, 4 strains and 2 strains were K5 and K57 respectively. The MLST results showed that 23/43 strains were ST11, followed by ST433(4/43), ST107(4/43), ST690(4/43), ST304(2/43), ST2058(1/43), ST1(1/43), ST146(1/43), ST914(1/43), ST2636(1/43), ST2637(1/43). As to the virulence factors, all 43 strains carried entB, ybtS and mrkD gene, followed by fimH (38/43), rmpA (14/43), allS (34/43), iutA (27/43), kfu (25/43), wcaG (21/43), aerobaction (16/43), fecIRA (15/43), shiF (10/43), magA (5/43) and pagO (5/43). This study demonstrated that high frequency of virulence factors emerging in high biofim bla KPC-2 producing strains. It also suggested that we should continue to focus on the toxicity variation and it's high time to enhance clinical awareness to the infections causing by Klebsiella pneumoniae . [ABSTRACT FROM AUTHOR]

Abstract: Mutations in PKHD1 (polycystic kidney and hepatic disease gene 1) gene cause the autosomal recessive polycystic kidney disease (ARPKD). Fibrocystin/polyductin (FPC), encoded by PKHD1, is a membrane-associated receptor-like protein. Although it is widely accepted that cystogenesis is mostly due to aberrant cell proliferation and apoptosis, it is still unclear how apoptosis is regulated. The aim of this study is to analyze the relationship among apoptosis, phosphatidylinositol 3-kinase (PI3K)/Akt and nuclear factor κB (NF-κB) in FPC knockdown kidney cells. We show that PKHD1-silenced HEK293 cells demonstrate a higher PI3K/Akt activity. Selective inhibition of PI3K/Akt using LY294002 or wortmannin in these cells increases serum starvation-induced HEK293 cell apoptosis with a concomitant decrease in cell proliferation and higher caspase-3 activity. PI3K/Akt inhibition also leads to increased NF-κB activity in these cells. We conclude that the PI3K/Akt pathway is involved in apoptotic function in PKHD1-silenced cells, and PI3K/Akt inhibition correlates with upregulation of NF-κB activity. These observations provide a potential platform for determining FPC function and therapeutic investigation of ARPKD. [Copyright &y& Elsevier]

Abstract: Mutations in PKHD1 (polycystic kidney and hepatic disease gene 1) gene cause the autosomal recessive polycystic kidney disease (ARPKD). It is widely accepted that cystogenesis is owing to aberrant cell proliferation and apoptosis, increased fluid secretion, and extracellular matrix abnormality. Fibrocystin/polyductin (FPC), the encoded protein product by PKHD1, is a single transmembrane protein and believed to be a novel receptor-like molecule. FPC has been located mainly on the plasma membrane and cilium/basal body. However, its biological functions remain poorly understood. To investigate the roles of FPC in the pathogenesis of ARPKD, we searched for FPC-interacting proteins by yeast two-hybrid assay, and found a novel partner, prosaposin. Prosaposin is a glycoprotein with multiple functions. With GST pull-down assay and co-immunoprecipitation, we confirmed the interaction between FPC and prosaposin. In order to study the effects of FPC–prosaposin interaction on cell proliferation and apoptosis, we have made stable cell lines in which FPC was overexpressed or knocked down alone or in combination with prosaposin overexpression. By MTT assay, we found that FPC knockdown and prosaposin overexpression increased cell proliferation, respectively, while overexpression of FPC C-tail did the opposite. With apoptosis assay, we found that overexpression of FPC C-tail promoted cell apoptosis. However, overexpression of prosaposin significantly enhanced cell survival in FPC knockdown cells. All these findings indicated that FPC and prosaposin may play significant roles in regulation of cell proliferation and apoptosis. Taken together, we have disclosed a novel signaling pathway of FPC, which may be important for the pathogenesis of ARPKD. [ABSTRACT FROM AUTHOR]