Interplay Between Membrane Permeability and Enzymatic Barrier Leads to Antibiotic-Dependent Resistance in .

The interplay between membrane permeability alterations and the enzymatic barrier contributes to multidrug resistance. We assessed the specific effect of the efflux levels of the main efflux pumps (AcrAB and OqxAB), alone and associated with the loss of the main porins (OmpK35 and OMPK36), on the activity of various antibiotics by constructing a set of isogenic strains, including strains with plasmid-mediated β-lactamases (DHA-1, CTX-M-15, and OXA-48). The two pumps contributed to intrinsic chloramphenicol resistance and AcrAB to that of nalidixic acid and cefoxitin, whereas they had no impact on the activity of the other 11 antibiotics tested.

Differential contribution of AcrAB and OqxAB efflux pumps to multidrug resistance and virulence in Klebsiella pneumoniae.

Objectives: In Klebsiella pneumoniae, overexpression of the AcrAB efflux pump and the more recently described OqxAB efflux pump has been linked to an antibiotic cross-resistance phenotype, but the mechanisms of regulation are largely unknown. Moreover, while AcrAB has been shown to participate in K. pneumoniae virulence, the contribution of OqxAB has not yet been assessed.

Multilocus sequence typing and rtxA toxin gene sequencing analysis of Kingella kingae isolates demonstrates genetic diversity and international clones.

Background: Kingella kingae, a normal component of the upper respiratory flora, is being increasingly recognized as an important invasive pathogen in young children. Genetic diversity of this species has not been studied.

Methods: We analyzed 103 strains from different countries and clinical origins by a new multilocus sequence-typing (MLST) schema.

Cost and effectiveness of intrapartum group B streptococcus polymerase chain reaction screening for term deliveries.

Objective: To estimate the cost and consequences of intrapartum polymerase chain reaction (PCR) screening on early-onset group B streptococcal (GBS) disease compared with the antenatal lower vagina culture screening recommended in France.

Methods: This was a single-institution study comparing the intrapartum PCR screening strategy implemented in 2010 with antenatal culture strategy in place in 2009. Early-onset GBS disease in newborns was monitored exhaustively.