ABSTRACT
ABSTRACT Enterobacter cloacae and E. aerogenes have been increasingly reported as important opportunistic pathogens. In this study, a high prevalence of multi-drug resistant isolates from Brazil, harboring several β-lactamase encoding genes was found. Several virulence genes were observed in E. aerogenes, contrasting with the E. cloacae isolates which presented none.
Subject(s)
Humans , Male , Female , Adult , Middle Aged , Bacterial Proteins/metabolism , beta-Lactamases/metabolism , Enterobacter cloacae/isolation & purification , Enterobacter aerogenes/isolation & purification , Virulence Factors/metabolism , Enterobacteriaceae Infections/microbiology , Phylogeny , Bacterial Proteins/genetics , Virulence , beta-Lactamases/genetics , Brazil , Microbial Sensitivity Tests , Enterobacter cloacae/classification , Enterobacter cloacae/enzymology , Enterobacter cloacae/genetics , Enterobacter aerogenes/classification , Enterobacter aerogenes/enzymology , Enterobacter aerogenes/genetics , Virulence Factors/genetics , Middle Aged , Anti-Bacterial Agents/pharmacologyABSTRACT
The selection of new microorganisms able to produce antimicrobial compounds is hoped for to reduce their production costs and the side effects caused by synthetic drugs. Clavulanic acid is a β-lactam antibiotic produced by submerged culture, which is widely used in medicine as a powerful inhibitor of β-lactamases, enzymes produced by bacteria resistant to antibiotics such penicillin and cephalosporin. The purpose of this work was to select the best clavulanic acid producer among strains of Streptomyces belonging to the Microorganism Collection of the Department of Antibiotics of the Federal University of Pernambuco (DAUFPE). Initially, the strains were studied for their capacity to inhibit the action of β-lactamases produced by Klebsiella aerogenes ATCC 15380. From these results, five strains were selected to investigate the batch kinetics of growth and clavulanic acid production in submerged culture carried out in flasks. The results were compared with the ones obtained by Streptomyces clavuligerus ATCC 27064 selected as a control strain. The best clavulanic acid producer was Streptomyces DAUFPE 3060, molecularly identified as Streptomyces variabilis, which increased the clavulanic acid production by 28% compared to the control strain. This work contributes to the enlargement of knowledge on new Streptomyces wild strains able to produce clavulanic acid by submerged culture.
Subject(s)
Clavulanic Acid/metabolism , Enzyme Inhibitors/metabolism , Streptomyces/isolation & purification , Streptomyces/metabolism , Enterobacter aerogenes/enzymology , Mass Screening , Streptomyces/growth & development , beta-Lactamases/metabolismABSTRACT
Enterobacter spp. es un patógeno intrahospitalario que presenta múltiples mecanismos de resistencia a los antibióticos b-lactámicos. Se caracterizaron fenotípica y genotípicamente las diferentes b-lactamasas presentes en 27 aislamientos consecutivos e ininterrumpidos de Enterobacter spp. (25 Enterobacter cloacae y 2 Enterobacter aerogenes). También se evaluó la habilidad de diferentes métodos fenotípicos para detectar b-lactamasas de espectro extendido (BLEE) en estos microorganismos. En 15/27 aislamientos (63%) se observó resistencia a las cefalosporinas de tercera generación. En 12 de los aislamientos resistentes se detectó un alto nivel de producción de cefalosporinasa cromosómica, siendo 6 de ellos también productores de PER-2. Dicha resistencia en los 3 aislamientos restantes se debió exclusivamente a la presencia de BLEE, PER-2 en 2 de ellos y CTX-M-2 en un caso. Sólo CTX-M-2 se detectó con todas las cefalosporinas probadas en los ensayos de sinergia, utilizando el método de difusión, mientras que cefepima mejoró la detección de PER-2 en 7/8 aislamientos productores de esta BLEE, 4/8 utilizando la prueba de doble disco y 7/8 comparando discos de cefepima con y sin el agregado de ácido clavulánico. El método de dilución empleado solo detectó 1/9 BLEE al comparar las cefalosporinas con y sin el agregado de inhibidor.
Enterobacter spp. are becoming increasingly frequent nosocomial pathogens with multiple resistance mechanism to b-lactam antibiotics. We carried out the phenotypic and genotypic characterization of beta-lactamases in 27 Enterobacter spp. (25 Enterobacter cloacae y 2 Enterobacter aerogenes), as well as the ability of different extended spectrum b-lactamase (ESBL) screening methods. Resistance to third generation cephalosporins was observed in 15/27 (63%) isolates. Twelve resistant isolates produced high level chromosomal encoded AmpC b-lactamase; 6 of them were also producers of PER-2. Resistance to third generation cephalosporins in the remaining 3 isolates was due to the presence of ESBLs, PER-2 in 2 cases, and CTX-M-2 in the other. Only CTX-M-2 production was detected with all tested cephalosporins using difusion synergy tests, while cefepime improved ESBLs detection in 7/8 PER-2 producers, 4/8 in the inhibitor aproximation test and 7/8 with double disk test using cefepime containing disk with and without clavulanic acid. Dilution method, including cephalosporins with and without the inhibitor detected 1/9 ESBLs producers.