ABSTRACT
BACKGROUND: The prevalence of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae is increasing globally and is a major clinical concern. Between June 2008 and September 2009, 4% of patients in an intensive care unit (ICU) were found to be colonized or infected by strains of Klebsiella pneumoniae multiresistant to ceftazidime, ciprofloxacin, and tobramycin; an investigation was initiated and isolates were characterized by molecular typing and resistance patterns. METHODS: Antibiotic susceptibilities were determined by Vitek2®, Etest®, and agar dilution. Gene encoding beta-lactamases and plasmid-mediated quinolone resistance PMQR determinants (qnr, aac(6')-Ib) were characterized by PCR, sequencing, and transfer assays. DiversiLab® fingerprints were used to study the relatedness of isolates. RESULTS: Fourteen isolates co-expressing blaCTX-M15, qnrB1, and aac(6')-Ib-cr were identified. Genotypic analysis of these isolates identified 12 clonally related strains recovered from 10 patients. The increased prevalence of blaCTX-M15-qnrB1-aac(6')-Ib-cr-producing K. pneumoniae coincided with the presence in the ICU of a patient originally from Nigeria. This patient was infected by a strain not clonally related to the others but harbouring qnrB1 and aac(6')-Ib-cr genes, a finding not hitherto observed in France. We suspected transmission of resistance plasmids followed by rapid dissemination of the multiresistant K. pneumoniae clone by cross-transmission. CONCLUSION: This study highlights the importance of microbiological screening for multidrug-resistant strains in ICUs, particularly among patients from regions in which multidrug-resistant bacteria are known to exist.
ABSTRACT
BACKGROUND: Phosphoregulation of signal transduction pathways is a complex series of reactions that may modulate the cellular response to ischemia-reperfusion (I-R). The aim of this study was to evaluate the effect of normothermic liver I/R-induced apoptosis on phosphorylation and activation of signal proteins in tyrosine kinase pathways. MATERIALS AND METHODS: In rats, a segmental normothermic ischemia of the liver was induced for 120 min. Liver apoptosis was determined using terminal deoxynucleotide-transferase-mediated deoxyuridine triphosphate nick end labeling assay, and activity of caspases-3 and -7 was determined by fluorescence. Liver tyrosine phosphorylation of proteins was examined by Western blot analysis. RESULTS: Normothermic I-R resulted in increased in vivo caspases-3 and -7 activity and in liver apoptosis. Shc tyrosine phosphorylation and activation of ERK1/2 were increased after reperfusion, while tyrosine phosphorylation of IRS-1 and activation of PKB/Akt were decreased. CONCLUSIONS: Normothermic liver I-R leads to increased apoptosis and to modifications in protein tyrosine phosphorylation pathways.
Subject(s)
Apoptosis/physiology , Insulin Receptor Substrate Proteins/metabolism , Liver/blood supply , Phosphotyrosine/metabolism , Protein-Tyrosine Kinases/metabolism , Reperfusion Injury/physiopathology , Signal Transduction/physiology , Animals , Caspase 3/metabolism , Caspase 7/metabolism , In Situ Nick-End Labeling , Liver/pathology , Male , Phosphorylation , Rats , Rats, Inbred Lew , Receptor, Insulin/metabolismABSTRACT
BACKGROUND: The aim of this study was to evaluate the role of the pro-apoptotic molecule Fas Ligand (FasL) in 120 min normothermic ischemia-reperfusion (I-R) induced apoptosis in rat liver treated or not with Z-Asp-cmk caspase inhibitor. MATERIALS AND METHODS: Rats were divided into two groups: group 1, control, PBS administration; group 2, Z-Asp-cmk treatment. Z-Asp-cmk was injected intravenously, 2 min before induction of 120 min of normothermic liver ischemia. Immunohistochemical detection of apoptotic liver cells was carried out using the TUNEL method. Fas and FasL expression were measured by qualitative reverse transcription polymerase chain reaction (RT-PCR), Northern and western blot, and by immunofluorescence labeling, in ischemic and non-ischemic liver lobes at different times after reperfusion. RESULTS: FasL mRNA and protein expression were increased in ischemic liver, while Fas receptor mRNA levels remained unchanged. Pre-treatment of rats with Z-Asp-cmk caspase inhibitor reduced liver apoptosis, but did not modify FasL mRNA levels. CONCLUSIONS: These results suggest that the pro-apoptotic molecule FasL is involved in the induction of liver apoptosis following I-R.
