Rapid Genotyping of Campylobacter coli Strains from Poultry Meat by PFGE, Sau-PCR, and fla-DGGE.

The genotyping of Campylobacter coli was done using three methods, pulsed-field gel electrophoresis (PFGE), Sau-polymerase chain reaction (Sau-PCR), and denaturing gradient gel electrophoresis assay of flagellin gene (fla-DGGE) and the characteristics of these assays were compared. The results showed that a total of 53 strains of C. coli were isolated from chicken and duck samples in three markets. All isolates were clustered into 31, 33, and 15 different patterns with Simpson's index of diversity (SID) values of 0.972, 0.974, and 0.919, respectively. Sau-PCR assay was simpler, more rapid, and had higher discriminatory power than PFGE assay. Fla-DGGE assay could detect and illustrate the number of contamination types of C. jejuni and C. coli without cultivation, which saved more time and cost than Sau-PCR and PFGE assays. Therefore, Sau-PCR and fla-DGGE assays are both rapid, economical, and easy to perform, which have the potential to be promising and accessible for primary laboratories in genotyping C. coli strains.

Intergenic region polymorphism analysis: a novel genotyping method for Klebsiella pneumoniae.

AIMS: The ability to distinguish between Klebsiella pneumoniae strains is critical for outbreak investigations. A new typing method, intergenic region polymorphism analysis (IRPA), was developed, validated, and the discriminatory power was determined by comparison with multiple-locus variable-number tandem repeat analysis (MLVA) in this study. METHODS AND RESULTS: This method is based on the idea that every IRPA locus (polymorphic fragment of intergenic regions present in one strain but not in other strains or different fragment sizes in other strains) could divide strains into different genotypes. A 9-loci IRPA scheme was designed to type 64 K. pneumoniae isolates. Five IRPA loci were identified that conferred the same level of discrimination as the 9-loci initially examined. Among these K. pneumoniae isolates, 7.81% (5/64), 6.25% (4/64), 4.96% (3/64), 9.38% (6/64), and 1.56% (1/64) were capsular serotypes K1, K2, K5, K20, and K54, respectively. The discriminatory power of the IRPA method was better than that of MLVA expressed in Simpson's index of diversity (SI) at 0.997 and 0.988, respectively. The congruent analysis of the IRPA method and MLVA showed moderate congruence between the two methods (AR = 0.378). The AW indicated that if IRPA data are availabl, one can accurately predict the MLVA cluster. CONCLUSION: The IRPA method was found to have higher discriminatory power than MLVA and allowed for simpler band profile interpretation. The IRPA method is a rapid, simple, and high-resolution technique for molecular typing of K. pneumoniae.

Comparison of pulsed-field gel electrophoresis and a novel amplified intergenic locus polymorphism method for molecular typing of Campylobacter jejuni.

Campylobacter is regarded as the leading cause of zoonotic diseases and Campylobacter jejuni (C. jejuni) is one of the predominant pathogenic species. To track C. jejuni infections, various genotyping methods have been used. In this study, amplified intergenic locus polymorphism (AILP) was used to type C. jejuni for the first time. To confirm its feasibility, pulsed-field gel electrophoresis (PFGE) was performed as a control, and the results obtained by the AILP and PFGE methods were compared. Fifty-one isolates were resolved into 34 and 29 different genotypes with Simpson's indices of 0.976 and 0.967 using the AILP and PFGE methods, respectively. The adjusted Rand coefficient of the two approaches was as high as 0.845. In summary, the data showed that the two genotyping methods were similar for discriminating isolates and were both appropriate methods to distinguish whether two isolates were indistinguishable, but the AILP was faster and less costly than PFGE. Therefore, the AILP is a reliable, rapid, and highly discriminative method to genotype C. jejuni collected from poultry meat, which is helpful to effectively monitor C. jejuni.

Subtyping of Campylobacter coli isolated from raw poultry meat in retail markets using amplified intergenic locus polymorphism - A novel rapid subtyping method.

In order to provide more phylogenetic information of Campylobacter coli in large-scale epidemiological investigation, this work was undertaken to develop a novel genotyping method based on amplified intergenic locus polymorphism (AILP), by using pulsed-field gel electrophoresis (PFGE; using SmaI enzymes) as control. Eleven pairs of primers were selected to type C. coli strains for this purpose. A total of 68 C. coli isolates recovered from 51 retail raw chicken and 37 retail raw duck were subtyped. The Simpson's index of diversity (SID) of AILP and PFGE, as well as the adjusted Rand index (AR) and the adjusted Wallace coefficient (AW) between AILP and PFGE, were calculated. The new AILP method differentiated 68 C. coli isolates into 55 different subtypes (SID = 0.993), compared with 46 different profiles obtained from PFGE (SID = 0.980). The SID value of the AILP method was improved with the increasing number of primers, and a combination of 7 loci was selected as the optimal combination. The congruent analysis of the AILP method and PFGE showed moderate congruence between the two methods (AR = 0.462). The AW indicated that if AILP data is the available one can confidently predict the PFGE cluster. The results of this study showed that the AILP method had higher discrimination than PFGE and also allowed for significant reduction in time and cost.

Nanocomplexation between thymol and soy protein isolate and its improvements on stability and antibacterial properties of thymol.

The complexation of thymol with soy protein isolate (SPI) at various mixing mass ratios, as well as some physicochemical characteristics, stability and antibacterial properties of the resultant complexes, was evaluated. The loading capacity of thymol in complexes formed at a mixing mass ratio of 2.5:12 was 10.36%, and the particles were spherical with a z-average diameter less than 110 nm. Fluorescence spectroscopy results indicated the SPI-thymol nanocomplexes were formed mainly through hydrophobic interactions. Upon nanocomplexation, the solubility, sustained release, thermal stability and antibacterial activity of thymol were greatly improved. Moreover, the encapsulation efficiency and solubility of thymol in complexes were improved with the increasing mixing mass ratio, while the stability and antibacterial activity of thymol were not significantly different among all the complexes. These findings suggest that SPI could be used as a nanocarrier for improving solubility and stability of thymol.