Inducible  -lactamase in Enterobacter

Abstract

S U M M A R YProduction of P-lactamase by nine strains of the genus Enterobacter (eight Enterobacter cloacae, one E. aerogenes) was studied to determine its inducibility. Induction was observed with benzylpenicillin (500 ,ag./ml.) in all except one strain. Cultures were examined to locate the enzyme; it was found that in exponential growth the enzyme was cell-bound, and in stationary phase cultures much of it was in the culture medium. Maximum enzyme activity was only demonstrated after cell-breakage. Substrate profiles of crude enzyme preparations were examined and it was observed that the enzymes were 20-80 times more active against cephalosporins than against benzylpenicillin. Evidence is presented which suggests that one strain of E. cloacae produced two /?-lactamases, an inducible cephalosporinase and a constitutive penicilli nase.

Drug Resistance of Enteric Bacteria

“…As to $-lactamases used in this experiment, penicillinase is a constitutive enzyme while cephalosporinase is generally inducible. It was also reported that cephalosporinases produced by strans of Pseudomonas [12,18] and Enterobacter [10] are inducible enzymes.…”

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).…”

Pseudomonas Aeruginosa AmpR Transcriptional Regulatory Network

“…The genes ampR and ampC have been found in many organisms (93)(94)(95)(96)(97). In systems with inducible ampC, the ampR gene is always present adjacent to ampC but is divergently transcribed (98)(99)(100).…”

“…The amp genes were first discovered in Enterobacter cloacae to confer resistance to β-lactams (93) and later in other members of Enterobacteriaceae (94)(95)(96)(97). The products of amp genes in E. cloacae and other organisms include the AmpC β-lactamase, the AmpG permease, a putative AmpE permease, the AmpD cytoplasmic amidase, and the transcriptional regulator AmpR (93)(94)(95)(96)(97).…”

“…The products of amp genes in E. cloacae and other organisms include the AmpC β-lactamase, the AmpG permease, a putative AmpE permease, the AmpD cytoplasmic amidase, and the transcriptional regulator AmpR (93)(94)(95)(96)(97). Recent studies have identified another permease, AmpP that is required for β-lactamase induction in P. aeruginosa (406).…”