Storage of <i>Escherichia coli</i> Strains Containing Plasmid DNA in Liquid Nitrogen

Breese, M. D.; Sharp, Richard

doi:10.1111/j.1365-2672.1980.tb05207.x

Cited by 7 publications

(3 citation statements)

References 8 publications

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“…It is known that antibiotic resistance may be lost in stored bacteria ( Breese and Sharp, 1980 ) and that the number of antibiotic resistances in E. coli can vary significantly between isolates from various farm animal species ( van den Bogaard et al, 2001 ). Additionally, own results revealed that the type of isolation medium affected the detection of phylogenetic groups.…”

Section: Discussionmentioning

confidence: 99%

Antimicrobial-Resistant Escherichia coli Survived in Dust Samples for More than 20 Years

et al. 2016

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In a retrospective study, 119 sedimentation dust samples stored between five and 35 years from various barns of intensive livestock farming were evaluated for the occurrence of cultivatable Escherichia coli. Growth of E. coli occurred in 54 samples. Successful cultivation was achieved in samples from as early as 1994. The frequency of detection increased from earlier to later time periods, but the concentrations, which ranged between 3.4 × 102 and 1.1 × 105 colony-forming units per gram, did not correlate with sample age (Spearman rank correlation; p > 0.05). We hypothesize that E. coli cells survived in dust samples without cell division because of the storage conditions. Dry material (dust) with low water activities (arithmetic mean < 0.6) and storage at 4°C in the dark likely facilitated long-term survival. E. coli were isolated on MacConkey agar with and without ciprofloxacin supplementation. For 110 isolates (79 from non-supplemented media and 31 from supplemented media), we determined the E. coli phylotype and antimicrobial resistance. Six phylogenetic groups were identified. Phylogroups A and B1 predominated. Compared to group A, phylogroup B1 was significantly associated with growth on ciprofloxacin-supplemented media (chi-square test, p = 0.003). Furthermore, the antibiotic resistance profiles determined by a microdilution method revealed that isolates were phenotypically resistant to at least one antimicrobial substance and that more than 50% were resistant to a minimum of five out of 10 antibiotics tested. A linear mixed model was used to identify factors associated with the number of phenotypic resistances of individual isolates. Younger isolates and isolates from fattening poultry barns tended to be resistant to significantly more antibiotics than older isolates and those from laying-hen houses (p = 0.01 and p = 0.02, respectively). Sample origin and storage conditions may have influenced the number of antimicrobial resistances. Overall, we found that under particular conditions, dust from farm animal houses can be reservoirs for antimicrobial-resistant E. coli for at least 20 years. The survival strategies that allow E. coli to survive such long periods in environmental samples are not fully understood and could be an interesting research topic for future studies.

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Section: Discussionmentioning

confidence: 99%

Antimicrobial-Resistant Escherichia coli Survived in Dust Samples for More than 20 Years

et al. 2016

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“…Historically, the preservation methods that have been used include storage on agar slants, lyophilization, cryopreservation, and desiccation. There have been several reports regarding the effect that a chosen preservation method can have on bacteria (1,3,9,12), but no study has focused specifically on both the viability and plasmid stability of bacteria after extended storage (Ͼ5 years) or have involved a large number of strains (Ͼ20 strains).…”

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Effects of Long-Term Storage on Plasmid Stability in Bacillus anthracis

Marston

Hoffmaster

Wilson

et al. 2005

Appl Environ Microbiol

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The plasmid profiles of 619 cultures of Bacillus anthracis which had been isolated and stored between 1954 and 1989 were analyzed using the Laboratory Response Network real-time PCR assay targeting a chromosomal marker and both virulence plasmids (pXO1 and pXO2). The cultures were stored at ambient temperature on tryptic soy agar slants overlaid with mineral oil. When data were stratified by decade, there was a decreasing linear trend in the proportion of strains containing both plasmids with increased storage time (P < 0.001). There was no significant difference in the proportion of strains containing only pXO1 or strains containing only pXO2 (P ‫؍‬ 0.25), but there was a statistical interdependence between the two plasmids (P ‫؍‬ 0.004). Loss of viability of B. anthracis cultures stored on agar slants is also discussed.Preservation of microorganisms is an important component of microbiological research. Maintenance of a well-defined collection of isolates is crucial for providing reproducible results and continuity in research, as well as for validating newly developed diagnostic and detection methods and treatment and postexposure prophylaxis protocols. While the ultimate objectives for preservation are maximum viability, genetic stability, and prevention of contamination, the preservation method is often chosen primarily based on ease of recovery and cost. Historically, the preservation methods that have been used include storage on agar slants, lyophilization, cryopreservation, and desiccation. There have been several reports regarding the effect that a chosen preservation method can have on bacteria (1, 3, 9, 12), but no study has focused specifically on both the viability and plasmid stability of bacteria after extended storage (Ͼ5 years) or have involved a large number of strains (Ͼ20 strains).Bacillus anthracis, the etiologic agent of anthrax, has two principal virulence factors, the toxin complex and the polypeptide capsule, which are encoded on separate plasmids, designated pXO1 and pXO2, respectively. Consequently, understanding plasmid stability during storage in a culture collection is especially important for B. anthracis. The plasmid profiles of a large collection of B. anthracis isolates that had been stored at the Centers for Disease Control and Prevention from the 1950s through the 1980s were studied to assess the effects of long-term storage on the stability of pXO1 and pXO2. MATERIALS AND METHODSIsolates. Of 1,150 storage slants, 769 were cultured successfully; the isolates on the remaining slants were no longer viable. All isolates had been stored at room temperature on tryptic soy agar slants overlaid with mineral oil in glass screw-cap tubes. The collection was stored in several different physical locations at the Centers for Disease Control and Prevention. For each slant, the mineral oil was removed from the tube, and 5 ml of heart infusion broth (Remel, Lenexa, KS) was added. The surface of the agar was scraped with a loop to suspend spores on the slant in the broth. The tube was then i...

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“…These include lyophilization (1), drying from the liquid state in vacuo (2), deep-frozen slopes (3), soil cultures (4), storage on agar slants overlaid with mineral oil (5,6), and preservation in liquid nitrogen (7). PELL and SNEATH (8) tested the survival of bacteria after freezing them in a medium containing l5° (v/v) glycerol and subsequent storage at temperatures of 4°C or 22°C.…”

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confidence: 99%