Recurrent outbreaks of Serratia marcescens among neonates and infants at a pediatric department: an outbreak analysis.

PURPOSE: Serratia marcescens is a known cause of bloodstream infections (BSIs) and outbreaks in neonates receiving intensive care. Our aim was to analyze clinical and epidemiological characteristics of two outbreaks detected in our unit to prevent and control further epidemic infections. METHODS: Two episodes of BSI outbreaks in neonates have been investigated in a 20-month period at a pediatric department of a medical university in Hungary. We collected all S. marcescens strains that were isolated in the study period, and two strains that were isolated before the outbreaks. Strains were analyzed by pulsed-field gel electrophoresis (PFGE). Clinical data were collected for the BSIs during and between the outbreaks (n = 14). RESULTS: Out of the 28 S. marcescens isolates investigated by PFGE, 16 were blood isolates. All isolates represented four PFGE types. Pathogenic strains that caused epidemic BSIs were related to a single PFGE type (SM009). Strains with the same pulsotype could be detected before, between, and after the outbreak periods from surveillance cultures of neonates, and a water tap in the infant care unit despite intensive infection control measures. Case fatality rate of BSIs was 29 %. Rate of complications in central nervous system was high: 3/14 neonates developed meningitis. CONCLUSIONS: Rapid spread and high mortality rate of S. marcescens infections necessitate a high suspicion when isolating this species in neonatal intensive care. Early identification of outbreaks is essential, that can be facilitated by determination of clonal relatedness using molecular methods, and with regular surveillance cultures of patients and environment

SSR analysis of the Medicago truncatula SARDI core collection reveals substantial diversity and unusual genotype dispersal throughout the Mediterranean basin

The world's oldest and largest Medicago truncatula collection is housed at the South Australian Research and Development Institute (SARDI). We used six simple sequence repeat (SSR) loci to analyse the genetic diversity and relationships between randomly selected individuals from 192 accessions in the core collection. M. truncatula is composed of three subspecies (ssp.): ssp. truncatula, ssp. longeaculeata, and ssp. tricycla. Analysis at the level of six SSR loci supports the concept of ssp. tricycla, all the samples of which showed unique alleles at two loci. Contingency Chi-squared tests were significant between ssp. tricycla and ssp. truncatula at four loci, suggesting a barrier to gene flow between these subspecies. In accessions defined as ssp. longeaculeata, no unique allelic distribution or diagnostic sizes were observed, suggesting this apparent ssp. is a morphological variant of ssp. truncatula. The data also suggest M. truncatula that exhibits unusually wide genotype dispersal throughout its native Mediterranean region, possibly due to animal and trade-related movements. Our results showed the collection to be highly diverse, exhibiting an average of 25 SSR alleles per locus, with over 90% of individuals showing discrete genotypes. The rich diversity of the SARDI collection provides an invaluable resource for studying natural allelic variation of M. truncatula. To efficiently exploit the variation in the SARDI collection, we have defined a subset of accessions (n = 61) that maximises the diversity