Broad host range of streptococcal macrolide resistance plasmids.

Four macrolide-lincosamide-streptogramin B resistance plasmids transferred into 13 recipients belonging to Streptococcus, Staphylococcus, and Listeria genera. The plasmids were stably maintained in all new hosts except Streptococcus sanguis, Streptococcus pneumoniae, Staphylococcus aureus, and Listeria innocua and were identical to those found in the corresponding donor strains.

Translocation of antibiotic resistance markers of a plasmid-free Streptococcus pyogenes (group A) strain into different streptococcal hemolysin plasmids.

Wild-type strain A454 (Streptococcus pyogenes) transferred en bloc its erythromycin (Em) and tetracycline (Tc) resistance markers into several plasmid-free streptococcal recipients. No plasmid DNA was detected in either the wild-type or the transconjugant strains. Crosses were performed between A454 and S.

[Antibiotic resistance genetic basis of human origin streptococci (author's transl)].

One hundred strains of group A, B, C, D (S faecalis, S. faecium, S. bovis) F, G, S.

High-level aminoglycoside resistance in group A, B, G, D (Streptococcus bovis), and viridans streptococci.

Of 20 clinical isolates of group A, B, G, D (Streptococcus bovis), and viridans streptococci, 5 transferred their antibiotic resistance markers into streptococcal recipients at a low frequency (10(-4) to 10(-8)) in the apparent absence of extrachromosomal elements. All strains carried genetic markers for high-level resistance to streptomycin, kanamycin, neomycin, lividomycin A, and ribostamycin, as well as resistance to macrolides and related drugs, tetracycline, and chloramphenicol.

Conjugative R plasmids in group C and G streptococci.

Two streptococcal isolates of groups C and G harbored conjugative R plasmids with molecular weights of 17 X 10(6) (pIP646) and 20 X 10(6) (pIP920). These plasmids carried genetic markers for resistance to macrolides and related drugs, as well as to chloramphenicol (pIP920), and have very similar HindIII restriction enzyme patterns.

High-level, plasmid-borne resistance to gentamicin in Streptococcus faecalis subsp. zymogenes.

Each of three isolates of Streptococcus faecalis subsp. zymogenes harbored three R plasmids and a hemolysin-bacteriocin plasmid. The plasmids carried by one of these strains were physically characterized after their conjugative transfer.

Physical studies of a Staphylococcus aureus plasmid mediating resistance to streptogramins, lincosamins and aminoglycosides.

Previous studies have demonstrated that resistance to three groups of drugs (streptogramins, lincosamins and aminoglycosides) was plasmid borne in a clinical isolate of Staphylococcus aureus. This plasmid, referred to as pIP524, was transferred in mixed culture or transduced into a plasmid-free host and analyzed for size, molecular weight and replication control. Plasmid pIP524 is a new member of the class of "large" plasmids (8.

R plasmids in Streptococcus agalactiae (group B).

Two plasmids determining resistance to tetracycline (RIP500) and to chloramphenicol, erythromycin, lincomycin, and pristinamycin I (RIP501) were isolated from a strain of Streptococcus agalactiae. The frequency-of-resistance loss is very low for RIP500 (<3 x 10(4)) but higher for RIP501 (the efficiency was dependent upon the curing agents and incubation temperature and varied between 0.5 and 96%).

[Identification of two plasmids isolated from a bacteriocinogenic strain of Clostridium perfringens].

Two plasmids were found and studied in the bacteriocinogenic strain N5 of Clostridium perfringens: one is a bacteriocinogenic factor (MW=5.7 X 10(6)) and the other a cryptic plasmid (MW 32.4 X 10(6)).

Physical studies of a plasmid mediating tetracycline resistance and hydrogen sulfide production in Escherichia coli.

Tetracycline resistance and hydrogen sulfide production have been previously found to be plasmid-mediated in a naturally-occurring strain of Escherichia coli; both functions are specified by a single conjugative plasmid called pIP231(Te-H2S); pIP231DNA was isolated as covalently closed molecules in dye-buoyant density gradients. The base ratio of the DNA was found to be 50% GC by density gradient analysis. Electron micrographs of plasmid molecules showed a contour length of 20 +/- 2 mum (40 +/- 4 X 10(6) daltons).

[Plasmids controlling the resistance to several antibiotics in C. perfringens type A, strain 659].

A strain of C. perfringens type A, isolated from a patient, was found to be resistant to four antibiotics: tetracycline (Tet), chloramphénicol (Chl), erythromycin (Ero) and clindamycin (Cli). Clones resistant to only two drugs (Tet-Chl or Ero-Cli), or sensitive to all drugs were found in cultures of the wild-type strain treated by acridine dyes or ethidium bromide.

Tetracycline resistance in Haemophilus influenzae is plasmid-linked.

A strain of Haemophilus influenzae resistant to tetracycline (MIC 16-32 mug/ml) was "cured" of tetracycline resistance by ethidium bromide. DNA centrifugation in cesium chloride + ethidium bromide density gradients showed the existence of a band of non-chromosomal DNA molecules in the original resistant strain. This band was not found in lysates of a strain "cured" of tetracycline resistance by ethidium bromide.