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PubMed1976

New plasmid-mediated nucleotidylation of aminoglycoside antibiotics in Staphlococcus aureus.

A wild-type strain of Staphylococcus aureus, which inactivates a wide variety of aminoglycosides (except the gentamicin components), has been found to harbor a plasmid (RAp01) that mediates the biosynthesis of a nucleotidyltransferase. This enzyme modifies the 4'-hydroxy function of these antibiotics. The plasmid has been studied, the enzyme responsible for this resistance pattern has been isolated by affinity chromatography, and its kinetics and physicochemistry have been characterized. The target of this enzyme has also been located by demonstrating the structure of one inactivated compound, 4'-(O)-adenylyltobramycin.

Aminoglycosides↗
PubMed1977

Drug resistance and R plasmids in Salmonella typhi isolated in Korea.

A total of 949 strains of Salmonella typhi isolated in Korea from 1968 to 1975 were tested for drug resistance and distribution of R plasmids. Resistance was mostly restricted to streptomycin (SM) and sulfisomidine (SA), singly or in combination, at a low degree. A small number of strains (1.5%) were resistant to four or more drugs: chloramphenicol (CM), tetracycline (TC), SM, SA, ampicillin (AP), and kanamycin (KM). No strain was resistant to nalidixic acid or to a 1:20 mixture of trimethoprim and sulfamethoxazole. Nor was there any strain singly resistant to CM, TC, AP, or KM. Transfer experiments of multiple-drug resistance to Escherichia coli ML1410 showed that all the strains resistant to four or more drugs carried R plasmids, whereas those weakly resistant to three or less drugs did not. The quadruply resistant strains carried one R plasmid determining CM, TC, SM, and SA resistance, and sextuply resistant ones carried two plasmids, one determining CM, TC, SM, and SA resistance and the other determining AP and KM resistance. One strain carrying a plasmid determining AP and KM resistance was also found. The transfer frequency of CM, TC, SM, and SA resistance was much higher than that of AP and KM resistance. The resistance of S. typhi was more efficiently transferred to E. coli at 25 degrees C than at 37 degrees C.

Conjugation, Genetic↗
PubMed1977

Changes in superhelical density of closed circular deoxyribonucleic acid by intercalation of anti-R-plasmid drugs and primaquine.

The following compounds, which possess anti-R-plasmid activity (Hahn and Ciak, 1976) in decreasing order, were shown by viscometric titration to change systematically the superhelical density of closed circular PM2 deoxyribonucleic acid in the manner of intercalators: ethidium bromide, quinacrine, acridine orange, quinine, chlorpromazine, chloroquine, and methylene blue. The same effect was caused by the antimalarial drug primaquine, which has not been tested for antiplasmid activity.

Acridines↗
PubMed1977

Transfer of a plasmid-specified beta-lactamase gene from Haemophilus influenzae.

A number of ampicillin-resistant strains of Haemophilus influenzae could donate a gene specifying the type IIIa (TEM) beta-lactamase to Haemophilus parainfluenzae, Escherichia coli, and Pseudomonas aeruginosa. Donor strains rapidly lost their ability to transfer ampicillin resistance on storage or subculture. Such strains also apparently contained a single species of covalently closed circular deoxyribonucleic acid of contour length 1.2 mum, equivalent to about 2.5 x 10(6) daltons. No species of plasmid deoxyribonucleic acid large enough to encode sex factor activity was detected. Despite this, transfer occurred to several bacterial genera in the presence of deoxyribonuclease, suggesting that transmissibility was by conjugation. The beta-lactamase gene was generally unstable after transfer and was lost in the absence of selection. Where stable transcipients were found, this was evidently by insertion of the beta-lactamase gene into the host chromosome. In P. aeruginosa insertion was always accompanied by induction of auxotrophy for adenine, suggesting insertion at a specific site. It is believed that insertion also occurred at one site on the chromosome of Escherichia coli. Crypticity measurements for beta-lactamase activity showed that there was little or no penetration barrier to beta-lactam drugs in Haemophilus. This may explain the long delay in the acquisition of ampicillin resistance by this organism.

Ampicillin↗
PubMed1977

Plasmid-mediated chloramphenicol resistance in Haemophilus influenzae.

A clinical isolate of Haemophilus influenzae HC234 was found to be resistant to chloramphenicol and tetracycline. It was shown that both resistance markers are tranferable as one unit to other Haemophilus influenzae strains and also to Escherichia coli. Data are presented which indicate that conjugation is the most likely mechanism of resistance transfer. HC234 was shown to carry a single plasmid species with a molecular weight of 38 x 10(6).

Chloramphenicol↗
PubMed1977

Changing patterns of plasmid-mediated drug resistance during tetracycline therapy.

The patterns of drug resistance and the frequency of conjugative R plasmids in intestinal Escherichia coli from 88 patients treated for a skin disease (acne vulgaris) with low oral doses of tetracycline are reported. The proportion of patients with resistant bacteria was progressively greater in patients who received tetracycline for 1 week, 4 weeks, or longer (from 50 to 88%). No multiply drug-resistant bacteria were detected before treatment or after 1 week of treatment. After more than 4 weeks of treatment, multiply drug-resistant E. coli were isolated from about 50% of the patients. The origin and selection of R plasmid-determined multiple drug resistance are discussed.

Acne Vulgaris↗
PubMed1977

Resistance plasmid transfer by Serratia marcescens in urine.

Resistance plasmids were transferred in urine from a multi-drug-resistant Serratia marcescens to Escherichia coli. Transfer of resistance to kanamycin, tetracycline, chloramphenicol, streptomycin, ampicillin, and carbenicillin occurred readily after 4 h of incubation at room temperature (25 degrees C). The urinary catheter collection bag is postulated as a potential site for extraintestinal resistance plasmid transfer in the Enterobacteriaceae, especially for pathogens such as Serratia, which do not frequently colonize the intestinal tract.

Anti-Bacterial Agents↗
PubMed1977

Mobilization of morganocin 174 plasmid and kinetics of morganocin production in Proteus and Escherichia coli hosts.

Morganocin 174 is coded by a plasmid, Mor174. The plasmid is not self-transmissible but may be mobilized by resistance factor R772. Morganocin synthesis in all Proteus and Providencia strains carrying Mor174 was characterized by a longer lag period after induction and higher titers than in Escherichia coli B(Mor174). The low titers obtained in E. coli B(Mor174) are due to a heatstable inhibitor produced by this strain. Synthesis of morganocin is not constitutive and may be induced by ultraviolet irradiation or mitomycin C. Morganocin production is not influenced by the growth medium of the organism.

Bacteriocins↗
PubMed1977

Plasmid-mediated beta-lactamase production in Neisseria gonorrhoeae.

Several beta-lactamase-producing, penicillin-resistant strains of Neisseria gonorrhoeae were examined for R plasmids. Penicillin-resistant strains isolated from men returning from the Far East and their contacts contained a 4.4 x 10(6)-dalton plasmid in common. Transformation studies and the isolation of a spontaneous penicillin-susceptible segregant showed that the structural gene for beta-lactamase was part of the 4.4 x 10(6)-dalton plasmid. An additional penicillin-resistant gonococcal strain isolated in London was found to harbor a 3.2 x 10(6)-dalton R plasmid. Deoxyribonucleic acid (DNA)-DNA duplex studies revealed that the penicillin-resistant gonococcal isolates contained a significant portion (about 40%) of the transposable DNA sequence, TnA, which includes the beta-lactamase gene commonly found on R plasmids of the Enterobacteriaceae and Haemophilus influenzae.

DNA, Bacterial↗
PubMed1977

Pseudomonas aeruginosa strain isolated in France that carries a plasmid determining carbenicillin resistance.

A plasmid, R56Be, derived from a clinical strain of Pseudomonas aeruginosa isolated in France in 1973 has been studied. This plasmid confers resistance only to carbenicillin, and although freely transferable between unrelated strains of P. aeruginosa, its transfer from P. aeruginosa to Escherichia coli K-12 was undetectable. R56Be could not be isolated as covalently closed circular deoxyribonucleic acid, but the plasmid could be transduced intact by phage F116L. This suggests that its molecular weight does not exceed that of the phage genome (ca. 40 x 10(6)). In terms of its interaction with male and female sex-specific phages, its exclusion characteristics, and the main properties of beta-lactamase determined by them, R56Be is similar to the previously characterized plasmid RP1-1.

Carbenicillin↗
PubMed1977

Drug resistance in group D streptococci of clinical and nonclinical origin: prevalence, transferability, and plasmid properties.

Group D streptococci isolated from clinical specimens and from sewage were investigated with regard to resistance to tetracycline (Tc), erythromycin (Em), and chloramphenicol (Cm). The median values of the percentages of resistant strains from sewage were: for Tc, 14%; for Em, 2.8%; and for Cm, 0.1%. For the recent isolates of clinical origin, resistance percentages found were 58% for Tc, 12% for Em, and 14% for Cm, and, in comparison to clinical isolates from 1964, the incidence of drug resistance slightly increased. In strains of both sources, the drug resistance was often found to be transferable to another group D streptococcus, probably by conjugation. Two strains were able to transfer their Em resistance to a streptococcus strain of group B. No transfer of drug resistance to a group A streptococcus and Escherichia coli was observed. All beta-hemolytic streptococci were also bacteriocinogenic, and frequently these properties were found to be transferable. The function, size, and base composition of the plasmids of two drug-resistant Streptococcus faecalis strains were investigated; strain M439 harbors at least two conjugative plasmids: pRI401, molecular weight 30 x 10(6), coding for Tc resistance, and pRI402, molecular weight 41 x 10(6), coding for Em resistance. Strain M403 carries one single conjugative plasmid species, coding for Tc resistance. The molecular weight of this plasmid, pRI404, was 37 x 10(6). The guanine plus cytosine content of these plasmids was 35 to 36%.

Chloramphenicol↗
PubMed1977

Transferable plasmids mediating multiple-antibiotic resistance in Streptococcus faecalis subsp. liquefaciens.

In strain HK187 (Streptococcus faecalis subsp. liquefaciens) four plasmids were isolated. The molecular weights, as analyzed in neutral sucrose gradients and by electron microscopy, were found to be about 36 x 10(6), 31 x 10(6), 26 x 10(6), and 4 x 10(6). Plasmid 3, also designated pFK14, with a molecular weight of 26 x 10(6), was found to be responsible for resistance to chloramphenicol and erythromycin and also for high-level resistance to streptomycin and lincomycin. In mixed cultures these four resistances could be transferred with high frequency to a plasmid-free recipient, S. faecalis strain JH2-2.

DNA, Bacterial↗
PubMed1977

Transfer of plasmid-borne beta-lactamase in Neisseria gonorrhoeae.

Neisseria gonorrhoeae strain GC82 contains a plasmid specifying a beta-lactamase (beta-Lam(+)). Mixed incubation of strain GC82 with a penicillin-susceptible (beta-Lam(-)), streptomycin-resistant mutant of strain GC9 results in the expression of beta-lactamase activity and streptomycin resistance in the transcipients. The frequency of transfer of the plasmid-specified resistance to penicillin seems to be proportional to the initial input ratio of the mating mixture of donor to recipient and to correlate positively with bacterial density. Cell-to-cell transmission of the deoxyribonucleic acid (DNA) appears to be by a conjugal mechanism or, alternatively, by an as yet undescribed transducing phage. Additionally, whole-cell DNA from a beta-lactamase-producing strain could be used to transform streptomycin-resistant recipients, resulting in the expression of both beta-lactamase activity and streptomycin resistance in the transformants, and purified gonococcal plasmid DNA transformed Escherichia coli but not the gonococcus. Circular DNA extracted from donor GC82 comprised three molecular species (approximately 2.7, 4.8, and 25 megadaltons [Mdal]), whereas the recipients GC9-S (Str(r)) contained only the 2.7-Mdal cryptic DNA species. DNA from the GC9-S82 (Str(r), beta-Lam(+)) transcipient contained a 4.8-Mdal species in addition to the cryptic molecular species (2.7 Mdal). The finding that the transcipient will not retransfer beta-lactamase is consistent with the hypothesis that the 25-Mdal plasmid promotes mobilization of the smaller 4.8-Mdal R plasmid.

DNA, Bacterial↗
PubMed1972

Phosphorylation of lividomycin by Escherichia coli carrying an R factor.

A lividomycin-phosphorylating enzyme from a lividomycin-resistant strain of Escherichia coli carrying an R factor was partially purified by fractionation with ammonium sulfate and Sephadex G-100 column chromatography. The enzyme inactivated, in the presence of adenosine triphosphate and Mg(2+), several antibiotics having a d-ribose moiety linked to 2-deoxystreptamine, i.e., lividomycin A and B, neomycin, paromomycin, and vistamycin, but did not inactivate the kanamycins, streptomycin, or the gentamicin C components. Chemical studies of the inactivated product suggested that the phosphorylated site of the inactivated lividomycin was the hydroxyl group of the d-ribose moiety.

Drug Resistance, Microbial↗
PubMed1973

Characterization of R factor beta-lactamases by the acidimetric method.

The properties and regulation of beta-lactamases produced by certain R factors derived from ampicillin-resistant strains of Escherichia coli and Klebsiella were characterized. beta-Lactamase activity was determined by the acidimetric method with phenol red as indicator. The sensitivity of this assay was increased by employing phosphate buffer at a final concentration of 0.4 mm; as little as 0.05 unit (1 unit equals the amount of beta-lactamase that hydrolyzes 1 mumole of benzyl penicillin per hr at pH 7.6 and 25 C) could be detected. This assay is rapid and convenient and appears to be superior to other methods currently employed to assay R factor beta-lactamases. Two classes of beta-lactamases were distinguished on the basis of substrate profile, heat inactivation, and K(m) values. The regulation of most of these R factor beta-lactamases, like certain other R factor enzymes, is subject to cyclic adenosine monophosphate-mediated catabolite repression.

Drug Resistance, Microbial↗