Some Properties of the Beta-Lactamase Genes in Staphylococcus epidermidis

Abstract

Eighty-three per cent of 200 different freshly isolated cultures of Staphylococcus epidermidis produced beta lactamase. Growth in the presence of acridine orange or ethidium bromide or growth at 44 C resulted in a high frequency of loss of the beta lactamase genes in some strains of S. epidermidis . The relationship between beta-lactamase production and resistance to mercuric, cadmium and arsenate ions differed from that observed in Staphylococcus aureus . It is postulated that the genes for beta lactamase in certain strains of S. epidermidis are on a plasmid.

Curing of Citrobacter spp. Strains Antibiotic Resistance Harboring Plasmids Using Novel Physical, Chemical and Natural Substances

“…Therefore, curing experiments using plant extracts, chemical compounds, or physical agents may remove only one plasmid, two, or all of them, or they may not remove or affect their plasmid content. Therefore, the resistance pattern of pathogenic bacteria may or may not change [26].…”

العلاقة بين مقاومة المعادن الثقيلة وإنتاج إنزيم بيتا لاكتاماز في بعض أنواع البكتيريا المسببة للأمراض

“…Small inocula of β-lactamase positive strains for each bacterial isolates were inculate in nutrient broth containing 12.5 µg/ml of acridin orange for 24 hr at 37 ċ (8).…”

“…The results illustrated that most of isolates were resistant to all heavy metals, because the bacteria have evolved several types of resistance mechanisms. These mechanisms were included the efflux of metal ions outside the cell, accumulation and complexation of the metal ions inside the cell and reduction of the heavy metal ions to a less toxic state (8,9).…”

Curing the Drug Resistance Plasmid in E. Coli O157:h7

“…This curing was carried out according to (Baldwin and Strickland, 1969). Ten ml of LB broth inoculated with single colony of E. coli isolate, after inoculation for 24 h at 37 °C, 10 ml LB broth culture inoculated with 0.2 ml of bacterial culture, incubated with shaking (100 rpm at 46 °C for 24 h), serial dilutions were prepared up to 10 -7 , then 0.1 ml from last three dilutions spread on nutrient agar plates and incubated at 37 °C for 24 h. After incubation time, fifty colonies were transferred to nutrient agar plate and incubated over night at 37 randomly chosen, picked up and transferred to Muller Hinton agar plates and tested for antibiotic sensitivity pattern incubated at 37 °C for 24 h. After overnight incubation the percentages of curing colonies for antibiotic sensitivity pattern were calculated.…”