Effects of ethidium bromide on growth and on loss of the penicillinase plasmid of Staphylococcus aureus.
نویسندگان
چکیده
Ethidium bromide (EB) was more efficient than ethyl violet or rifampin as a curing agent for the penicillinase plasmids of Staphylococcus aureus strains. The effects of EB on growth and on the loss of the penicillinase plasmid of PS 81 were studied in detail. The growth rates of PS 81 and an EB-cured derivative were identical in broth, but the cured derivative had a shorter lag in the presence of added 6 x 10(-6)m EB. The shortened lag was due to prior exposure to EB as the cured derivative and an EB-treated but uncured strain of PS 81 gave identical growth lag and growth rates in the presence of EB. The curing of PS 81 by EB occurs in three phases. After a 4 to 5 hr lag, there is a 100-fold increase in the number of penicillinase-negative cells, and the proportion of cured cells continues to rise until 10 to 12 hr. Thereafter, the population becomes refractory to further curing, and the proportion of penicillinase-negative cells remains constant at about 20% of the total. Penicillinase-positive survivors of EB treatment showed increased EB resistance and were cured at lower rates upon subsequent EB treatment. Isolated colonies of the parental strain PS 81 were heterogeneous in their EB sensitivity. Thus, EB does not competitively favor spontaneously cured penicillinase-negative cells but appears to act in a manner analogous to acridine orange on the plasmids of enteric bacteria.
منابع مشابه
Ethidium bromide resistance, a new marker on the staphylococcal penicillinase plasmid.
A strain of Staphylococcus aureus resistant to ethidium bromide is described. The genetic determinants for the resistance are present on the same plasmid as the penicillinase genes.
متن کاملLoss of the penicillinase plasmid after treatment of Staphylococcus aureus with sodium dodecyl sulfate.
Two strains of Staphylococcus aureus (PC1 and 196E), when grown in medium containing 0.002% sodium dodecyl sulfate (SDS), showed from 96.1 to 100% loss of the ability to produce penicillinase. Resistance to cadmium and zinc was lost concomitantly with the ability to produce penicillinase. A comparison of the rate of curing by SDS with the curing effects exerted by elevated temperature and ethid...
متن کاملNature of the genetic determinant controlling exfoliative toxin production in Staphylococcus aureus.
Phage group II Staphylococcus aureus has been identified as the etiological agent of the staphylococcal scaleded skin syndrome. The development of an animal model system permitted fulfillment of Koch's postulates and recognition of exfoliative toxin (ET) as being responsible for some of the clinical manifestations of this syndrome. Initial studies directed toward associating a lysogenic phage w...
متن کاملTransduction and elimination of resistance determinants in methicillin-resistant Staphylococcus aureus.
Elimination and transduction of drug resistance was examined in methicillin-resistant strains of Staphylococcus aureus. Irreversible spontaneous loss and "curing" by aging of cultures and by treatment with ethidium bromide indicated that the determinants for penicillinase production and chloramphenicol resistance, and probably also for neomycin resistance, were located extrachromosomally. On th...
متن کاملPattern of antibiotic and heavy-metal ion resistance in recent hospital isolates of Staphylococcus aureus BY M. R. MILLAR, N. GRIFFIN AND N. KEYWORTH Departments of Medical Microbiology and Pathology, Leeds General Infirmary
Two hundred and one strains of Staphylococcus aureus isolated from in-patients and out-patients were examined for sensitivity to antibiotics, heavy-metal ions and ethidium bromide and for phage-typing pattern. Heavy-metal ion resistance was less frequent than reported in previous studies and was as frequent in penicillinase non-producing as producing strains. 'Methicillin-resistant' strains wer...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Journal of bacteriology
دوره 108 3 شماره
صفحات -
تاریخ انتشار 1971