Molecular subtyping and antimicrobial susceptibilities of Campylobacter coli isolates from diarrheal patients and food-producing animals in China.

The aim of this study was to determine the molecular subtyping and antimicrobial susceptibility characteristics of Campylobacter coli isolates from different sources in China. One hundred thirteen C. coli isolates were subtyped by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and porA and flaA short variable region (SVR) nucleotide sequences. Cluster analysis was performed based on the PFGE and sequence types (ST). Eighty-four PFGE patterns (SmaI) were observed in 113 isolates. Fifty-four STs (28 novel) and three clonal complexes (CC), 86% of which were clustered to CC828, were observed, as well as 52 porA and 37 flaA-SVR sequence alleles. MLST, porA, and flaA-SVR analysis demonstrated that many isolates from diarrheal patients shared identical genotypes with chicken isolates. Minimum inhibitory concentration values of 10 antibiotics were analyzed for 109 isolates isolated in 2011 using the E-test method. The most frequently observed resistance agents were nalidixic acid (100%) and ciprofloxacin (100%), followed by levofloxacin (99%), tetracycline (94%), metronidazole (93%), erythromycin (61%), streptomycin (72%), gentamicin (59%), ampicillin (50%), and chloramphenicol (29%). Multidrug resistance was detected in 108 of 109 C. coli isolates (99%).

[Three quantitative methods to continuously monitor Legionella in spring water].

OBJECTIVE: To compare the detection effect of Legionella pollution in spring water by three methods, namely traditional plating method, fluorescent quantitation PCR method and ethidium monoazide (EMA) fluorescent quantitation PCR method. METHODS: Every month (except May), we collected 11 water samples from the 5 selected hot spring pools in one hot spring resort in Beijing in 2011. A total of 121 water samples were collected, and then were detected by the above three methods qualitatively and quantitatively. RESULTS: In our study, the Legionella pollution rate was separately 74.4% (90/121), 100.0% (121/121) and 100.0% (121/121) by the above three methods. The quantitative value of Legionella in the 121 water samples detected by the three methods were around 0.10-216.00 colony-forming units (CFU)/ml, 1.47-1557.75 gene units (GU)/ml and 0.20-301.69 GU/ml, respectively. The median (25th and 75th percentiles) was 75.30 (32.51-192.10) GU/ml, 36.46 (16.08-91.21) GU/ml and 5.30 (0.00-33.70) CFU/ml, respectively. The difference in the quantitative value of Legionella detected by the three methods showed statistical significance (χ(2) = 187.900, P < 0.01). The quantitative value of Legionella detected by fluorescent quantitation PCR method was the highest, followed by the value Legionella detected by EMA-fluorescent quantitation PCR method and traditional plating method. CONCLUSION: The sensitivity of the PCR methods was higher than traditional plating method, in detecting Legionella pollution in spring water, especially the EMA- fluorescent quantitation PCR method, which was more suitable for detecting Legionella in water.

High prevalence, genetic diversity and intracellular growth ability of Legionella in hot spring environments.

BACKGROUND: Legionella is the causative agent of Legionnaires' disease, and hot springs are a major source of outbreaks of this disease. It is important from a public health perspective to survey hot spring environments for the presence of Legionella. METHODS: Prospective surveillance of the extent of Legionella pollution was conducted at three hot spring recreational areas in Beijing, China in 2011. Pulsed-field gel electrophoresis (PFGE) and sequence-based typing (SBT) were used to describe the genetic polymorphism of isolates. The intracellular growth ability of the isolates was determined by interacting with J774 cells and plating the dilutions onto BCYE agar plates. RESULTS: Overall, 51.9% of spring water samples showed Legionella-positive, and their concentrations ranged from 1 CFU/liter to 2,218 CFU/liter. The positive rates of Legionella were significantly associated with a free chlorine concentration of ≥0.2 mg/L, urea concentration of ≥0.05 mg/L, total microbial counts of ≥400 CFU/ml and total coliform of ≥3 MPN/L (p<0.01). The Legionella concentrations were significantly associated with sample temperature, pH, total microbial counts and total coliform (p<0.01). Legionella pneumophila was the most frequently isolated species (98.9%), and the isolated serogroups included serogroups 3 (25.3%), 6 (23.4%), 5 (19.2%), 1 (18.5%), 2 (10.2%), 8 (0.4%), 10 (0.8%), 9 (1.9%) and 12 (0.4%). Two hundred and twenty-eight isolates were analyzed by PFGE and 62 different patterns were obtained. Fifty-seven L. pneumophila isolates were selected for SBT analysis and divided into 35 different sequence types with 5 main clonal groups. All the 57 isolates had high intracellular growth ability. CONCLUSIONS: Our results demonstrated high prevalence and genetic polymorphism of Legionella in springs in Beijing, China, and the SBT and intracellular growth assay results suggested that the Legionella isolates of hot spring environments were pathogenic. Improved control and prevention strategies are urgently needed.

[Study on the status of pollution by Legionella species in hot spring vacation center and the related factors].

OBJECTIVE: To study the pollution status of Legionella species in hot spring vacation center and the related factors. METHODS: 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. RESULTS: 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. CONCLUSION: 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.