Culture Collections

NCTC strains in modern research

  NCTC in modern research - HOMEPAGE

 

Microorganisms and cell lines available from Public Health England’s Culture Collections are used regularly as characterised controls and are also used in research settings. The example below demonstrates how the research community used bacterial strains curated and provided by the National Collection of Type Cultures (NCTC) to address questions surrounding the origin and development of antimicrobial resistance in the UK1.

Vancomycin-resistant Enterococcus faecalis (VREfs) are among the most common pathogens that cause hospital acquired infection in Europe and North America2,3. Vancomycin has been in use since the late 1950s, and is prescribed to patients infected with penicillin or methicillin resistant infection. A letter to Nature Microbiology describes a study led by scientists at the University of Cambridge, which used whole genome sequencing and bioinformatics analysis to characterise isolates from UK hospitals1, 3. The study evaluates the strains in a global context using publicly available genome sequences and organisms available through NCTC and other microbial collections.

The study found that 90% of the hospital associated VREfs examined could be placed in three distinct groups, or lineages, that are active in the UK, two of which are distributed nationally and one confined to two hospitals. The two nationally distributed lineages were associated with previously described high-risk lineages (derived from hospital isolates in Europe) which had undergone multiple instances of antibiotic resistance gene loss and acquisition. In addition each of the three lineages contained a mixture of sensitive and resistant organisms4. A previously undescribed mutation rate for the core genome of Enterococcus faecalis was also defined, providing invaluable context for real time investigations of clinical outbreaks and further academic studies.

The majority of the NCTC strains used were isolated across the 20th century with all other strains used in the study having been sourced in 2001 or later.  NCTC 12201, a strain isolated in 1986 from one of the first reported vancomycin resistant enterococci infections in the UK, may represent the origin of one of the VREfs currently circulating in hospitals nationally3. The more recently isolated NCTC 13379 is the only organism in the study with a vanB gene, a related vancomycin resistance gene to vanA, which is more commonly found in clinical settings in the United States rather than Europe. Seven of the NCTC organisms included were isolated before 1951 and two from before 1921. The oldest isolate in each lineage was used as a reference when performing genomic analysis, offering insights as to how Enterococcus faecalis evolves over time.

It’s clear that the use of whole genome sequencing and powerful bioinfomatic processes allow clinicians and scientists to study pathogens in greater detail than previously possible. By using these high resolution investigative techniques and authenticated organisms from a selection of bio-resources such as NCTC this study has revealed much about the current status and history of vancomycin resistant Enterococcus faecalis disease in the UK.

 

Follow the NCTC 3000 whole genome sequencing project on Twitter @NCTC_3000

 

References

1. Kathy E. Raven, Sandra Reuter, Theodore Gouliouris, Rosy Reynolds, Julie E. Russell, Nicholas M. Brown, M. Estée Török, Julian Parkhill & Sharon J. Peacock. Genome-based characterization of hospital-adapted Enterococcus faecalis lineages. Nature Microbiology 1, Article number: 15033 (2016). doi:10.1038/nmicrobiol.2015.33

2. European Centre for Disease Prevention and Control. Point prevalence survey of healthcare-associated infections and antimicrobial use in the European acute care hospitals. ECDC doi 10.2900/86011 (2013).

3. Sievert, D. M. et al. Antimicrobial-resistant pathogens associated with healthcare-associated infections: summary of data reported to the National Healthcare Safety Network at the Centers for Disease Control and Prevention, 2009-2010. Infect. Control Hosp. Epidemiol. 34, 1–14 (2013).

4. Kuch, A. et al. Insight into antimicrobial susceptibility and population structure of contemporary human Enterococcus faecalis isolates from Europe. J. Antimicrob. Chemother.67, 551–8 (2012)

5. Uttley, A. H. C., Collins, C.H., Naidoo, J. & George, R. C. Vancomycin-resistant enterococci. Lancet 2, 57–58 (1988).

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