Cronobacter carriage in neonate and adult intestinal tracts.

A total of 7 Cronobacter strains were isolated from 703 fecal samples collected in Jinan from June 13 to December 30, 2011, with the positive rate of Cronobacter spp. being 1.0% (95% confidence interval 0.6%-1.4%). Three Cronobacter sakazakii stains were isolated from 157 fecal samples of healthy neonates (95% confidence interval 0.4%-5.5%). This number was slightly higher than that isolated from 273 fecal samples of healthy adults, in which 1 strain of C. sakazakii and 1 strain of Cronobacter malonaticus were isolated, and that from 173 fecal samples of adults with acute diarrhea, in which 1 strain of C. sakazakii and 1 strain of C. malonaticus were isolated, but the differences were not statistically significant (P>0.05). The Cronobacter isolates were all from different genetic sources. It should be noted that Cronobacter carriage may cause infection under certain conditions, especially in neonates.

Molecular characteristics of Neisseria meningitidis isolated during an outbreak in a jail: association with the spread and distribution of ST-4821 complex serogroup C clone in China.

OBJECTIVE: To characterize the meningococcal strains isolated from cases and close contacts with meningococcal disease associated with an outbreak in a jail in May 2010 by investigating the national distribution of hyperinvasive ST-4821 serogroup C clone associated with this outbreak. METHODS: The cases were described based on the clinical symptoms and laboratory results. Pharyngeal swabs were cultured for N. meningitidis from men in the jail. Meningococcal isolates were identified by serogrouping, pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST), respectively. Four hundred and sixteen serogroup C N. meningitidis strains were collected from 27 provinces between 2003 and 2010 for a nationwide survey and analyzed by PFGE and MLST. RESULTS: Three persons in a jail system were infected with invasive N. meningitidis serogroup C. All isolates tested had matching PFGE patterns and belonged to the multilocus sequence type (ST) 4821 clonal complex. All 47 N. meningitidis strains were identified from the pharyngeal swabs of 166 peoples in the jail, and 26 of them belonged to ST-4821 serogroup C clone, and 90.14% (375/416) serogroup C strains identified in the nationwide survey belonged to the ST-4821 complex. The ST-4821 serogroup C clone was spread nationwide, distributed in 24 provinces, especially in eastern provinces between 2003 and 2010. CONCLUSION: Endemic transmission and carriage rate of ST-4821 serogroup C clone are high in this jail system. The ST-4821 serogroup C clone is spreading in China and nationwide distributed despite the existence of some effective vaccines.

[Simulation of the depth profile of tritium based on X-ray spectrum measurement].

Tritium is very important fusion materials,it has been broad applied both in military area and in civil area. It is very important to study the depth profile and composition of tritium in materials. This thesis establishes the whole simulation method for tritium b-ray induced X-ray spectrometry technique and researches the algorithm of X-ray spectra simulation, and the X-ray spectrum and the depth and composition of tritium based on simulation has been investigated to expose their relationships. The results show that there is a corresponding relationship between depth profile and X-ray spectra, and the results lay a foundation for further research on inverse problem.