Purpose: Serratia marcescens is a common pathogen in the hospital environment and colonizes patients. It is a serious cause of nosocomial outbreaks of invasive infections. There is limited experience using polymerase chain reaction (PCR)-based randomly amplified polymorphic DNA (RAPD) method for typing of S. marcescens isolates for timely investigation of an outbreak. We sought to evaluate the performance of PCR-RAPD method using different primer sets compared to a reference method in the context of a neonatal intensive care unit (NICU) outbreak of invasive S. marcescens. Methods & Materials: Stored isolates of S. marcescens and cluster-related patient isolates over 2 months, were sub-cultured and genomic DNA was extracted. Blinded PCR amplification of each isolate DNA was performed using 4 primer sets, 2 of which were previously published primers for fingerprinting S. marcescens and 2 RAPD primers which were tested for the first time (272 P. aeruginosa and 270 B. cepacia primer sets). The PCR products were run on agarose gels, and the band patterns were compared visually and with the aid of computer analysis. Then the results were compared to those obtained from the traditional typing methods of pulse field gel electrophoresis (PFGE). Results: Overall, 4 blood isolates, 4 non-invasive samples, a control S. marcescens and a control Pseudomonas aeruginosa were included. All the invasive outbreak isolates (4 blood cultures from 3 different patients) were found to harbor identical S. marcesens strains using PFGE and RAPD typing methods, and they clustered separately from non-invasive isolates. Of the 4 primer sets used, the 272 P. aeruginosa primer gave the highest discrimination and the most number of bands allowing for accurate clustering of for the S. marcesens isolates. Results for RAPD were available within 24 hours from testing initiation and were replicable. Conclusion: In a small invasive S. marcescens outbreak in the NICU, typing by PCR-RAPD using the 272 P. aeruginosa primer set performed well compared to the reference method.. A particular attraction of this method is that it is economic and provides rapid results to inform infection control measures in real time. The use of PCR-RAPD could be a reasonable option for outbreak investigations of S. marcescens.

During a measles outbreak in British Columbia in 2010, a patient with clinical measles, confirmed by a positive IgM on the same day, was admitted to the Children’s Hospital. The patient's room was later determined not to meet airborne isolation standards, leading to a series of patient and staff exposures over 24 hours.

To analyse the genetic variability of EG95 sequences and provide guidance for EG95 vaccine application against Echinococcus granulosus (E. granulosus).We analysed EG95 polymorphism by collecting total 97 different E. granulosus isolates from 12 different host species that originated from 10 different countries. Multiple sequence alignments and the homology were performed by Lasergene 1 (DNASTAR Inc., Madison, WI), and the phylogenetic analysis was performed by using MEGA5.1 (CEMI, Tempe, AZ, USA). In addition, linear and conformational epitopes were analysed, including secondary structure, NXT/S glycosylation, fibronectin type III (FnIII) domain and glycosylphosphatidylinositol anchor signal (GPI-anchor). The secondary structure was predicted by PSIPRED method.Our results indicated that most isolates overall shared 72.6–100% identity in EG95 gene sequence with the published standard EG95 sequence, X90928. However, EG95 gene indeed has polymorphism in different isolates. Phylogenetic analysis showed that different isolates could be divided into three subgroups. Subgroup 1 contained 87 isolates while Subgroup 2 and Subgroup 3 consisted of 3 and 7 isolates, respectively. Four sequences cloned from oncosphere shared a high identity with the parental sequence of the current vaccine, X90928, and they belonged to Subgroup 1. However, in comparison to X90928, several amino acid mutations occurred in most isolates besides oncosphere, which potentially altered the immunodominant linear epitopes, glycosylation sites and secondary structures in EG95 genes. All these variations might change their previous antigenicity and thereby affecting the efficacy of current EG95 vaccine.This study reveals the genetic variability of EG95 sequences in different E. granulosus isolates, and proposed that more vaccination trials would be needed to test the effectiveness of current EG95 vaccine against distinct isolates in different countries.