Antimicrobial resistance and resistance mechanisms of Enterobacteriaceae in ICU and non-ICU wards in Europe and North America: SMART 2011-2013.

Intensive care units (ICUs) are often described as hotbeds of antimicrobial resistance, with high rates of extended-spectrum ß-lactamase (ESBL)-producing and multidrug-resistant (MDR) Enterobacteriaceae. Data from the SMART study were used to examine differences between the susceptibility of Enterobacteriaceae from ICU and non-ICU wards in Europe and North America. In total, 21,470 Enterobacteriaceae isolates from intra-abdominal and urinary tract infections were collected at 90 sites in 20 European and North American countries in 2011-2013. Susceptibility and ESBL phenotypes were determined using the CLSI broth microdilution method and breakpoints. Susceptibility was lower and ESBL and MDR rates were higher in ICUs, with much greater ICU/non-ICU differences in Europe than North America. Susceptibility was lower and ESBL and MDR rates were higher in Europe than in North America in both patient locations. Resistance among Enterobacteriaceae in Europe was largely driven by Klebsiella pneumoniae, which had high rates of ESBLs (41.2% in ICUs; mostly CTX-M) and carbapenemases (13.2%; mostly KPC and OXA). For all Enterobacteriaceae combined, only ertapenem and amikacin inhibited >90% of isolates in ICUs in both regions. In North America, ertapenem, imipenem and amikacin inhibited >90% of K. pneumoniae from ICUs, whereas in Europe only amikacin did. ESBL and MDR rates varied considerably within Europe. Antimicrobial resistance was higher in Europe than North America, especially in ICUs. Further surveillance at the country, hospital and even patient ward level, and investigation of reasons for these findings, would be useful for the development of effective strategies to reduce antimicrobial resistance in ICUs.

The phage N4 virion RNA polymerase catalytic domain is related to single-subunit RNA polymerases.

In vitro, bacteriophage N4 virion RNA polymerase (vRNAP) recognizes in vivo sites of transcription initiation on single-stranded templates. N4 vRNAP promoters are comprised of a hairpin structure and conserved sequences. Here, we show that vRNAP consists of a single 3500 amino acid polypeptide, and we define and characterize a transcriptionally active 1106 amino acid domain (mini-vRNAP). Biochemical and genetic characterization of this domain indicates that, despite its peculiar promoter specificity and lack of extensive sequence similarity to other DNA-dependent RNA polymerases, mini-vRNAP is related to the family of T7-like RNA polymerases.

N4 RNA polymerase II, a heterodimeric RNA polymerase with homology to the single-subunit family of RNA polymerases.

Bacteriophage N4 middle genes are transcribed by a phage-coded, heterodimeric, rifampin-resistant RNA polymerase, N4 RNA polymerase II (N4 RNAPII). Sequencing and transcriptional analysis revealed that the genes encoding the two subunits comprising N4 RNAPII are translated from a common transcript initiating at the N4 early promoter Pe3. These genes code for proteins of 269 and 404 amino acid residues with sequence similarity to the single-subunit, phage-like RNA polymerases. The genes encoding the N4 RNAPII subunits, as well as a synthetic construct encoding a fusion polypeptide, have been cloned and expressed. Both the individually expressed subunits and the fusion polypeptide reconstitute functional enzymes in vivo and in vitro.