RESUMO
Multidrug-resistant organisms are increasing in healthcare settings, and there are few antimicrobials available to treat infections from these bacteria. Pseudomonas aeruginosa is an opportunistic pathogen in burn patients and individuals with cystic fibrosis (CF), and a leading cause of nosocomial infections. P. aeruginosa is inherently resistant to many antibiotics and can develop resistance to others, limiting treatment options. P. aeruginosa has multiple sigma factors to regulate transcription. The alternative sigma factor, RpoN (σ54), regulates many virulence genes and is linked to antibiotic resistance. Recently, we described a cis-acting peptide, RpoN*, which is a "molecular roadblock", binding consensus promoters at the -24 site, blocking transcription. RpoN* reduces virulence of P. aeruginosa laboratory strains, but its effects in clinical isolates was unknown. We investigated the effects of RpoN* on phenotypically varied P. aeruginosa strains isolated from CF patients. RpoN* expression reduced motility, biofilm formation, and pathogenesis in a P. aeruginosa-C. elegans infection model. Furthermore, we investigated RpoN* effects on antibiotic susceptibility in a laboratory strain. RpoN* expression increased susceptibility to several beta-lactam-based antibiotics in strain P. aeruginosa PA19660 Xen5. We show that using a cis-acting peptide to block RpoN consensus promoters has potential clinical implications in reducing virulence and improving antibiotic susceptibility.
Assuntos
Antibacterianos/farmacologia , Fibrose Cística/complicações , Farmacorresistência Bacteriana , Infecções por Pseudomonas/etiologia , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/metabolismo , RNA Polimerase Sigma 54/antagonistas & inibidores , Animais , Antibacterianos/uso terapêutico , Biofilmes/efeitos dos fármacos , Suscetibilidade a Doenças , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Infecções por Pseudomonas/diagnóstico , Infecções por Pseudomonas/tratamento farmacológico , Pseudomonas aeruginosa/isolamento & purificação , Pseudomonas aeruginosa/patogenicidade , RNA Polimerase Sigma 54/genética , VirulênciaRESUMO
Northern elephant seal (NES) serum concentrations of total immunoglobulin (Ig) G, an IgG sub-class, and an IgM-like protein were determined by capture immunoassay using three monoclonal antibodies with specificities for Ig of members of the Phocidae pinniped family. These assays were calibrated for use with NES sera using affinity column purified Ig. Concentrations of these Ig populations were estimated in adult female sera sampled at two time points during the lactation period, as well as sera from their pups collected during the first 5 weeks after birth. In pups, concentrations of the IgM-like protein was found to increase rapidly post-partum. In some individuals, values reached mean concentrations within 10-14 days. In addition, rapid increases in pup total IgG and IgG sub-class concentrations were also observed. Collectively, these findings suggest that the majority of post-partum increases in serum Ig can be accounted for by de-novo synthesis.