Major articleTemporal changes in pulsed-field gel electrophoresis banding in vancomycin-resistant Enterococcus faecium and implications for outbreak investigations
Section snippets
Study design and population
Previously collected, frozen VREF clinical or surveillance isolates at Northwestern Memorial Hospital, an 897-bed academic medical center in Chicago, Illinois, were studied. Clinical isolates were collected at the discretion of the treating physician and were obtained from blood, cerebrospinal fluid, or urine. Rectal surveillance isolates were collected per the infection control and prevention departmental protocol. Rectal surveillance cultures are obtained on admission and weekly for patients
Results
Six patients with a total of 28 isolates met inclusion criteria (Table 1). The median number of isolates per patient was 4.5 (range 4-6 isolates) and the median time followed for each patient was 198 days (range 77-504 days). The longest length of time between any 2 consecutive isolates was 362 days and the shortest length of time was 5 days. The average percent difference for each single band difference was 3.7%. On average, there were 17.9 bands from the SmaI pattern. Isolates between
Discussion
Because isolates are currently considered closely related when they are within a 3-band difference, we wished to determine the time point at which >3-band difference was probable for a single isolate on the basis of temporal genetic variation.9 Our data provide empiric evidence that outbreak identification via PFGE for VREF should consider the time frame in which the isolates were obtained. Specifically, no strain differed >3 bands before 150 days, indicating that this might be a reasonable
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Pulsed-field gel electrophoresis (PFGE): A review of the “gold standard” for bacteria typing and current alternatives
2019, Infection, Genetics and EvolutionCitation Excerpt :PFGE was also used in a recent outbreak caused by consumption of Romaine Lettuce contaminated by the same bacteria in the USA (https://www.cdc.gov/ecoli/2018/o157h7-04-18/index.html). In outbreak investigations using PFGE, attention to collection dates of tested isolates is of importance, as banding patterns for bacteria such as vancomycin-resistant Enterococcus faecium might change in as short as 150 days, and obscure clonal assignment (McLaughlin et al., 2013). PFGE typing is used in the food industry to monitor potential bacteria contaminants of food produce.
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2017, Diagnostic Microbiology and Infectious DiseaseCitation Excerpt :This study was approved by the institutional review boards at Northwestern University and Midwestern University. VRE from clinical or surveillance cultures were collected as previously described (McLaughlin et al. 2013). Briefly, clinical isolates were obtained as clinically indicated from blood, cerebrospinal fluid, or urine.
Virulence of Vancomycin-resistant enterococcus faecium according to linezolid resistance and clinical outbreak status
2013, Antimicrobial Agents and Chemotherapy
This study was supported in part by a Midwestern University Chicago College of Pharmacy Faculty Research Stimulation Grant.
Conflicts of interest: None to report.