ABSTRACT
The polymerase chain reaction (PCR) and the conventional culture method of detecting thermophilic Campylobacter species in duck and chicken samples from two locations in the province of Laguna, Philippines, were compared. Three Campylobacter jejuni and five C. coli strains were isolated from a total of 135 duck and chicken samples from both methods. The PCR technique, however, was found to be more sensitive, accurate and rapid than the conventional culture method. The specificity of two sets of published primers, C442-C490 (specific for C. jejuni, C. coli and C. lari) and CL2-CR3 (specific for C. jejuni) were confirmed with reference and field strains. To improve detection, a lysate was prepared by boiling cells in Triton X-100, and then used as template for PCR to detect Campylobacter from spiked and naturally contaminated chicken rinse. For spiked chicken samples, a 17-h Meuller-Hinton Broth enrichment for the chicken rinse resulted in an improved sensitivity at 31.7 CFU/g using C442-C490. This enrichment-PCR tandem also detected thermophilic Campylobacter from 1 out of 21 native chicken samples from a wet market. To our knowledge, this is the first report of thermophilic Campylobacter isolation from poultry in the Philippines. The approaches described here could serve as a basis for future surveillance and/or epidemiological studies on this emerging foodborne pathogen.
Subject(s)
Campylobacter coli/isolation & purification , Campylobacter jejuni/isolation & purification , Chickens/microbiology , DNA, Bacterial/analysis , Ducks/microbiology , Animals , Campylobacter coli/genetics , Campylobacter jejuni/genetics , Colony Count, Microbial , Culture Media , Food Contamination , Food Microbiology , Philippines , Polymerase Chain Reaction/methods , Sensitivity and Specificity , Time FactorsABSTRACT
Molecular tools were used to analyze the genetic diversity and population structure of Xanthomonas oryzae pv. oryzicola, the bacterial leaf streak pathogen of rice in the Philippines. Representative pathogen strains were selected and used to assess resistance in rice germplasm. A partial genomic library of X. oryzae pv. oryzicola was constructed, and a 459-bp clone containing the repetitive DNA element R41 was selected as a probe for restriction fragment length polymorphism (RFLP) analysis and sequenced. R41 shared 44% sequence homology with the putative transposase gene of IS1112, an insertion element cloned from X. oryzae pv. oryzae. Using R41 as a probe for RFLP analysis, 26 band profiles were discerned in a collection of 123 strains of X. oryzae pv. oryzicola. Analysis of PstI digestion patterns of DNA from the same collection resolved 36 haplotypes. Several clusters of strains were detected after grouping of data based on either pR41 as a probe or Pst1 digestion patterns. However, based on bootstrap analysis, the clusters were not robust. Genetic diversity was high for the entire collection as well as within spatially and temporally defined subsets of strains. Even a set of strains collected from a single site at a single time was highly diverse. Strains representing the different DNA types were inoculated to a set of diverserice cultivars. Consistent rice varietal groupings were obtained from disease reaction data, but there was no correlation between pathogen isolate cluster and host reaction across inoculation trials. Isozyme group I of rice, representing tropical japonica and javanica germplasm, is a promising source of resistance to bacterial leaf streak.
