Characterization of beta-lactamase induction in Enterobacter cloacae

Abstract

The induction of ,-lactamase was studied in a strain of Enterobacter cloacae. A wide variety of P-lactam compounds were found to induce ,-lactamase in this organism, and the degree of induction was directly related to the stability of the inducer to degradation by the enzyme. The kinetics of the induction process were consistent with a system normally under repressor control, suggesting a direct interaction of the P-lactam compound with a repressor protein in the E. cloacae cells. Although these characteristics are common to many inducible systems in gram-negative organisms, the induction of 1-lactamase in this strain was not subject to catabolite repression with glucose and remained unaffected by exogenous cyclic AMP in the culture medium. This suggests that the organization and function of the P-lactamase regulatory genes in E. cloacae are unlike those of other inducible gene systems, such as those composing the well-characterized lactose operon in Escherichia coli.

Treatment failures of cefotaxime and latamoxef in meningitis caused by Enterobacter and Serratia spp.

“…The amount of /Mactamase produced by a strain was given as the arithmetic mean of at least three completely independent determinations. /?-Lactamase induction was assessed using an adaptation of the method of Gootz & Sanders (1983), with cefoxitin, 10 mg/1 final concentration, as inducer. Controls, without cefoxitin, were run simultaneously.…”

Actividad inhibitoria de dihidroxifenilpropenona sobre β-lactamasa de Enterobacter cloacae: estudio preliminar en el desarrollo de fármacos para enfrentar la resistencia bacteriana

“…Se inició con un cultivo de 24 horas del aislamiento clínico de E. cloacae, el cual se ajustó a una población de microorganismo equivalente a 0,5 en la escala de McFarland, y se incubó a 37 °C durante dos horas. A continuación se adicionó penicilina G como inductor de la producción de enzima en tres concentraciones diferentes, 0,5; 1,0; 2,0 mg/ml, y se incubó durante cinco horas con agitación continua con el fin de estandarizar la concentración efectiva para la inducción (44,45). Para lograr este propósito se determinó el porcentaje de hidrólisis del nitrocefín de cada uno de los extractos crudos de betalactamasa durante diferentes tiempos de incubación, los ensayos espectrofotométricos se realizaron haciendo el seguimiento a la hidrólisis del nitrocefín (100 μM) a una longitud de onda de 486 nm durante 60 minutos y a una temperatura de 20 °C (46).…”

“…Los cultivos de E. cloacae previamente inducidos para la producción de betalactamasa se centrifugaron durante 30 minutos a 2.500 rpm; los agregados celulares se suspendieron en agua desionizada y se sometieron a ciclos de ultrasonido (4 °C durante dos minutos en cuatro intervalos de 30 segundos) para liberar la enzima del espacio periplasmático; luego se centrifugaron las muestras durante 10 minutos y el sobrenadante (extracto total de betalactamasas) se almacenó a -20 °C y antes del estudio de cinética enzimática (45), se realizó la cuantificación de proteínas mediante el método BCA utilizando ácido bicincónico (Pierce BCA protein Assay Kit ™ ) (Thermo Scientific, Meridian, USA). Los extractos proteicos obtenidos se liofilizaron antes de su purificación en un equipo Eyela, PFR-1000 ™ (Tokio, Japón).…”

Nonspecific Induction of -lactamase in Enterobacter cloacae

“…It is well established that most p-lactam antibiotics appear to be affected by these enzymes either by hydrolysis or by the non-hydrolytic barrier mechanism (Gootz & Sanders, 1983;. In some cases, these enzymes are produced constitutively; however, induction generally occurs (Gootz & Sanders, 1983). Large amounts of enzyme are often produced by strains belonging to the genera Enterobacter, Serratia or Citrobacter, thus leading to a high degree of resistance against a wide variety of p-lactam antibiotics.…”

“…It is well established that most p-lactam antibiotics appear to be affected by these enzymes either by hydrolysis or by the non-hydrolytic barrier mechanism (Gootz & Sanders, 1983;. In some cases, these enzymes are produced constitutively; however, induction generally occurs (Gootz & Sanders, 1983).…”