Effect of EDTA-TRIS on an Escherichia coli isolate containing R plasmids

Wooley, Richard E.; Dickerson, Harry W.; Simmons, Karen; Shotts, Emmett B.; Brown, Justin R.

doi:10.1016/0378-1135(86)90042-8

Cited by 13 publications

(5 citation statements)

References 16 publications

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“…There has been previous interest in exploring ways in which the development or spread of resistance to an antimicrobial agent might be blocked at the genetic level, e.g., by suppressing the emergence of point mutations with antimutagenic agents, disrupting horizontal DNA transfer (5, 25, 32, 33), or promoting the curing of plasmids by chemical agents (3,16,24,32,33). However, the possibility of inhibiting gene conversion events to suppress the emergence of resistance has not been explored.…”

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confidence: 99%

Delayed Development of Linezolid Resistance in Staphylococcus aureus following Exposure to Low Levels of Antimicrobial Agents

Miller

O’Neill

Wilcox

et al. 2008

Antimicrob Agents Chemother

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The development of resistance to linezolid (LZD) in gram-positive bacteria depends on the mutation of a single 23S rRNA gene, followed by homologous recombination and gene conversion of the other alleles. We sought to inhibit this process in Staphylococcus aureus using a range of antibacterial agents, including some that suppress recombination. A model for the rapid selection of LZD resistance was developed which allowed the selection of LZD-resistant mutants with G2576T mutations in all five copies of the 23S rRNA gene following only 5 days of subculture. The emergence of LZD-resistant isolates was delayed by exposing cultures to low concentrations of various classes of antibiotics. All antibiotic classes were effective in delaying the selection of LZD-resistant mutants and, with the exception of fusidic acid (FUS) and rifampin (RIF), prolonged the selection window from 5 to ϳ15 days. Inhibitors of DNA processing were no more effective than any other class of antibiotics at suppressing resistance development. However, the unrelated antimicrobials FUS and RIF were particularly effective at preventing the emergence of LZD resistance, prolonging the selection window from 5 to 25 days. The enhanced suppressive effect of FUS and RIF on the development of LZD resistance was lost in a recA-deficient host, suggesting that these drugs affect recA-dependent recombination. Furthermore, FUS and RIF were shown to be effective inhibitors of homologous recombination of a plasmid into the staphylococcal chromosome. We suggest that RIF or FUS in combination with LZD may have a role in preventing the emergence of LZD resistance.The development of resistance to linezolid (LZD) in clinical isolates of Staphylococcus aureus and enterococci involves the generation of mutations in one of the multiple 23S rRNA gene copies targeted by the drug, followed by homologous recombination between the remaining 23S rRNA gene copies, i.e., a process of gene conversion (15,18,30). In addition to LZD resistance, gene conversion has also been implicated in the emergence of resistance to penicillin in pneumococci (4, 23) and, possibly, also in the emergence of resistance to macrolides in staphylococci, which, like LZD resistance, appears to result from alterations to rRNA operons (26).There has been previous interest in exploring ways in which the development or spread of resistance to an antimicrobial agent might be blocked at the genetic level, e.g., by suppressing the emergence of point mutations with antimutagenic agents, disrupting horizontal DNA transfer (5, 25, 32, 33), or promoting the curing of plasmids by chemical agents (3,16,24,32,33). However, the possibility of inhibiting gene conversion events to suppress the emergence of resistance has not been explored. We have examined a variety of antimicrobial agents, including those that inhibit DNA processing, for their ability to interfere with the development of LZD resistance in S. aureus. Spiral plating techniques, which require successive serial transfers in the presence of LZD for many we...

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confidence: 99%

Delayed Development of Linezolid Resistance in Staphylococcus aureus following Exposure to Low Levels of Antimicrobial Agents

Miller

O’Neill

Wilcox

et al. 2008

Antimicrob Agents Chemother

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“…Isolates Bio027K, 5-90-156, and MSU originated from Mississippi; isolate 162 was from Virginia. Escherichia coli strain 1932 (Wooley et al 1986) was used as the intermediate R plasmid recipient. This strain contains no plasmids and is nalidixic acid-resistant, and colistin-and Rometsensitive.…”

Section: Methodsmentioning

confidence: 99%

Plasmid-Mediated Romet Resistance ofEdwardsiella ictaluri

Starliper

Cooper

Shotts

et al. 1993

Journal of Aquatic Animal Health

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Romet®, a potentiated sulfa drug composed of five parts sulfadimethoxine and one part onnetoprim, is used to treat channel catfish Ictalurus punctatus infected with Edwardsiella ictaluri, the causal agent of enteric septicemia of catfish (ESQ. Recently, several Romet-resistant isolates of E. ictaluri were isolated from channel catfish that had died from ESC in Virginia and Mississippi. This antimicrobial resistance was determined to be plasmid-encoded, as shown by agarose gel electrophoresis of plasmid DNA, and by the fact that the plasmid and associated antimicrobial resistance could be transferred to a recipient by single-step conjugation. Size of the R plasmid was approximately 55 kilobase pairs. Plasmids also conferred resistance to tetracycline, oxytetracycline, streptomycin, trimethoprim, and SXT (another potentiated sulfonamide, composed of trimethoprim and sulfamethoxazole). Each Romet-resistant E. ictaluri isolate was mated with a plasmid recipient, the Romet-sensitive Escherichia coti isolate 1932. Transconjugates were selected by plating on Mueller-Hinton agar that contained antimicrobials, and the mean transfer frequency was 1.483 x 10~3 transconjugates per donor cell in the mating mixture. Each E. coli transconjugate was then mated with 20 Romet-sensitive isolates of E. ictaluri to assess the propensity of these E. ictaluri isolates to accept the R plasmid. The average transfer frequency when E. ictaluri isolates of channel catfish origin (N = 14) were used as recipients was 1.197 x 10~2 transconjugates per donor cell in the mating mixture; mean transfer frequency when E. ictaluri isolates not originating from channel catfish were used was 1.019 x 10~3 transconjugates per donor cell, which was significantly less (P = 0.0002).

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“… 1 Human isolate [ 52 ]; 2 chicken isolate [ 51 ], 3 pR100 (chloramphenicol resistance); pRSA (kanamycin resistance) plasmid; pSDb1–pSTm1 (tetracycline resistance) plasmids. 4 #transconjugants/#recipients.…”

Section: Figurementioning

confidence: 99%

Conditions Necessary for the Transfer of Antimicrobial Resistance in Poultry Litter

et al. 2023

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Animal manures contain a large and diverse reservoir of antimicrobial resistance (AMR) genes that could potentially spillover into the general population through transfer of AMR to antibiotic-susceptible pathogens. The ability of poultry litter microbiota to transmit AMR was examined in this study. Abundance of phenotypic AMR was assessed for litter microbiota to the antibiotics: ampicillin (Ap; 25 μg/mL), chloramphenicol (Cm; 25 μg/mL), streptomycin (Sm; 100 μg/mL), and tetracycline (Tc; 25 μg/mL). qPCR was used to estimate gene load of streptomycin-resistance and sulfonamide-resistance genes aadA1 and sul1, respectively, in the poultry litter community. AMR gene load was determined relative to total bacterial abundance using 16S rRNA qPCR. Poultry litter contained 108 CFU/g, with Gram-negative enterics representing a minor population (<104 CFU/g). There was high abundance of resistance to Sm (106 to 107 CFU/g) and Tc (106 to 107 CFU/g) and a sizeable antimicrobial-resistance gene load in regards to gene copies per bacterial genome (aadA1: 0.0001–0.0060 and sul1: 0.0355–0.2455). While plasmid transfer was observed from Escherichia coli R100, as an F-plasmid donor control, to the Salmonella recipient in vitro, no AMR Salmonella were detected in a poultry litter microcosm with the inclusion of E. coli R100. Confirmatory experiments showed that isolated poultry litter bacteria were not interfering with plasmid transfer in filter matings. As no R100 transfer was observed at 25 °C, conjugative plasmid pRSA was chosen for its high plasmid transfer frequency (10−4 to 10−5) at 25 °C. While E. coli strain background influenced the persistence of pRSA in poultry litter, no plasmid transfer to Salmonella was ever observed. Although poultry litter microbiota contains a significant AMR gene load, potential to transmit resistance is low under conditions commonly used to assess plasmid conjugation.

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Effect of EDTA-TRIS on an Escherichia coli isolate containing R plasmids

Cited by 13 publications

References 16 publications

Delayed Development of Linezolid Resistance in Staphylococcus aureus following Exposure to Low Levels of Antimicrobial Agents

Delayed Development of Linezolid Resistance in Staphylococcus aureus following Exposure to Low Levels of Antimicrobial Agents

Plasmid-Mediated Romet Resistance ofEdwardsiella ictaluri

Conditions Necessary for the Transfer of Antimicrobial Resistance in Poultry Litter

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