A simple disk pre-diffusion test to predict in vitro aztreonam/avibactam activity against NDM-producing Klebsiella pneumoniae complex.

Objectives: The aim of this study was to describe a simple test to predict in vitro efficacy of aztreonam/avibactam (ATM-AVI) combination based on a pre-diffusion assay involving routinely available ceftazidime/avibactam (CAZ-AVI) and aztreonam (ATM) disks.

Methods: A total of 113 non-repetitive NDM-producing Klebsiella had the species identified by multiplex PCR. Minimum inhibitory concentrations (MICs) for ATM and ATM-AVI were determined by broth microdilution.

Genotyping of paired KPC-producing Klebsiella pneumoniae isolates with and without divergent polymyxin B susceptibility profiles.

Polymyxins are still used mainly in treating infections caused by carbapenem-resistant Klebsiella pneumoniae worldwide. The most frequent mechanism of acquired resistance to polymyxins in Gram-negative bacilli is the occurrence of mutations in chromosomal genes regulating operons responsible for lipopolysaccharide modification. As we observed at Santa Casa de São Paulo hospital the occurrence of infections caused by isolates resistant to polymyxins in patients previously treated with this antimicrobial, and new infections caused by the same polymyxin-susceptible species, in this study, we aimed to determine the clonality of consecutive K.

Dissemination of bla is mediated by IncX plasmids and the Tn6435 transposon.

In Enterobacteriaceae, the bla genes have been identified on plasmids in different regions of the world. The OXA-370 is a plasmid-encoded OXA- enzyme reported in two distinct regions of Brazil. Recently, we demonstrate that the bla gene is disseminated among several Enterobacteriaceae species and clones, indicating a high potential for dissemination.

Frequency of Plasmid-Mediated AmpC β-Lactamases in Escherichia coli Isolates from Urine Samples in São Paulo, Brazil.

Plasmid-mediated AmpC β-lactamases (PMACBLs) in Enterobacteriaceae encode resistance to third-generation cephalosporins, and these can mediate carbapenem resistance when associated with porin loss. However, no standardized phenotypic method is available for detecting these enzymes in the clinical microbiology laboratory. Limited data are available concerning the frequency of PMACBLs in Enterobacteriaceae in Brazil.

fosI Is a New Integron-Associated Gene Cassette Encoding Reduced Susceptibility to Fosfomycin.

In this work, we demonstrate that the fosI gene encodes a predicted small protein with 134 amino acids and determines reduced susceptibility to fosfomycin. It raised the MIC from 0.125 to 6 μg/ml when the pBRA100 plasmid was introduced into Escherichia coli TOP10 and to 16 μg/ml when the gene was cloned into the pBC_SK(-) vector and expressed in E.