Study on molecular typing by pulsed-field gel electrophoresis of food Listeria monocytogenes isolates from eight province (municipalities) of China / 中华流行病学杂志

<p><b>OBJECTIVE</b>To analyse the molecular types of Listeria (L.) monocytogenes, and to construct the standard China L. monocytogenes pulsed-field gel electrophoresis (PFGE) subtyping database, using the international standardized L. monocytogenes-PFGE protocol.</p><p><b>METHODS</b>118 L. monocytogenes strains isolated from 8 provinces or municipalities of China were subtyped according to L. monocytogenes-PFGE protocol.</p><p><b>RESULTS</b>118 strains of L. monocytogenes were divided into 39 subtypes. In the 39 subtypes, 37 strains (31.36%) were GX6A160004 pattern, showing it was the predominant Lm subtype in China.</p><p><b>CONCLUSION</b>Data from molecular typing suggested that the predominant Lm strains were distributed in different regions of China. PulseNet China-Lm database was constructed which was valuable for the molecular subtyping-based surveillance of L. monocytogenes.</p>

Using direct enzyme linked immunosorbent assay for the detection of IgG antibody on Bartonella henselae among healthy people in Changping, Beijing / 中华流行病学杂志

<p><b>OBJECTIVE</b>To detect Bartonella henselae IgG antibody among healthy people in Changping, Beijing.</p><p><b>METHODS</b>Using indirect enzyme linked immunosorbent assay (ELISA) and immunofluorescence antibody assay (IFA) to detect IgG antibody of Bartonella henselae among human beings.</p><p><b>RESULTS</b>The sensitivity and specificity of ELISA were 70.6% and 91.6% respectively, with the positive predictive value of serological test as 82.2%, and the negative predictive value as 84.9%, based on results of IFA. The positive rate was 34.5% among 357 healthy people on indirect ELISA but was 35.6% among 239 people with IFA.</p><p><b>CONCLUSION</b>The results indicated that the indirect ELISA was a very quick, sensitive and available method for detecting Bartonella henselae in human beings, as well as a high positive percent age of Bartonella henselae among the healthy people of Changping Beijing.</p>

Study on the status of pollution by Legionella species in hot spring vacation center and the related factors / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the pollution status of Legionella species in hot spring vacation center and the related factors.</p><p><b>METHODS</b>Field surveys were performed in four big hot spring vacation centers of Changping district. Uniform questionnaires was used and colony count was made together with the isolation of Legionella species from hot spring water based on mip gene typing.</p><p><b>RESULTS</b>47 isolates of Legionella pneumophila (Lp) from 87 samples showed 4 serotypes as Lp1, Lp6, Lp12, Lp5 with percent of 57.45%, 21.28%, 14.89%, 6.38% respectively. The hot spring centers controlled the temperature of recycled water between 34-47 degrees C by hot water heating and filtrating system. All the isolates were cultured from the hot water with temperature between 34-44 degrees C: 56.75% (21/37) in high temperature (40-47 degrees C) and 61.90% (26/42) in low temperature (34-39.9 degrees C). There were no statistically significant difference between the high and the low temperature samples (P > 0.05). In the four hot spring vacation centers, the pH value was under control at 6.4-7.3 and the ambient temperature was under control between 26-28 degrees C. The humidity was controlled between 56% -69% relative humidity, which were the best growing conditions for the Legionella species. Disinfectors as chlorine deviratives was used in the four hot spring vacation centers. Though the concentration of chlorine in the water was 0.3-0.5 mg/L, 14.29%-48.00% of the samples were still positive of having Legionella species.</p><p><b>CONCLUSION</b>The pollution of Legionella species was considered to be quite serious in the four hot spring vacation centers and the predominant serotype was Lp1. The pH and temperature of the hot spring water, ambient temperature and humidity and the way of heating up the water were the best conditions for the growth of Legionella species in these centers. Because of the high temperature of the hot spring water, chlorine of the disinfector volatilized quickly, affecting the effect of disinfection. The result revealed that water temperature achieving 44 degrees C could have had the effect of prevention.</p>