Typing of Salmonella Typhi strains isolated from Egypt by RAPD PCR

Random amplified polymorphic DNA-based molecular heterogeneity analysis of Salmonella enterica isolates from foods of animal origin

Aim:

This study aims to study the significance of random amplified polymorphic DNA (RAPD) typing in heterogeneity analysis of Salmonella serovars, isolated from foods of animal origin.

Materials and Methods:

Salmonella serovars isolated and identified from different foods of animal origin such as meat, milk, and egg by standard bacteriological methods. DNA isolated from all 10 isolates which are confirmed by biochemical and serotyping methods and then RAPD was performed using the primers OPB 10, primer 1290, NSC I, NSC II, and primer 3. Then, RAPD data were analyzed using the BioNumerics software, Belgium, Germany.

Results:

RAPD polymerase chain reaction (PCR) using five primers, namely OPB 10, primer 1290, NSC I, NSC II, and primer 3, classified the 10 isolates into 9, 10, 10, 7, and 10 RAPD-PCR types with discriminating powers of 0.1987, 0.423, 0.50889, 0.1842, and 0.2582, respectively. The phylogram constructed with NSC I profile classified isolates based on geographical origin. Primer 1290, NSC II, and primer 3 produced some uniform bands in all isolates indicating their binding ability in conserved genomic region. This study revealed that RAPD profile can be best used for finding out the heterogeneity at molecular level of Salmonella isolates in combination with other molecular and phenotypic typing techniques. Thus, our results support earlier observation of its significance by different workers on different Salmonella serotypes.

Conclusion:

Repeatability of RAPD-PCR is insufficient to distinguish genetic differences among Salmonella serovars.

The effective differentiation of Salmonella isolates using four PCR-based typing methods

AIMS

Discrimination of Salmonella strains below the species level is very important to trace the source of outbreaks. To this end molecular typing methods can be successfully applied to routine analysis in nonspecialized laboratories due to their simplicity and speed. Here, the discriminatory ability of four molecular typing methods was investigated in 74 Salmonella enterica isolates.

METHODS AND RESULTS

Salmonella strains isolated from human stool, blood, bone marrow, synovial fluid, ascites and urine sources in Iran during the years 2012 and 2013 were differentiated by random amplification of polymorphic DNA (RAPD), enterobacterial repetitive intergenic consensus (ERIC), repetitive extragenic palindromic (REP) and BOX repeat-based (BOXAIR) PCR methods. A total of 74 isolates were obtained, with 67 isolates belonging to eight serotypes/serogroups, while seven were nontypeable. The 74 strains produced 32 fingerprints with OPS-11 primers, 44 RAPD fingerprints using OPP-16 primers and 54 fingerprints with P1254 primers; their discriminatory index (DI) was 0·942, 0·978, and 0·984 respectively. BOXAIR fingerprinting produced 49 patterns (DI 0·985), while REP resulted in 55 patterns (DI 0·991) and ERIC in 48 fingerprints (DI 0·983). The discrimination of Salmonella isolates was improved when methods were combined. The combination of ERIC, REP and BOXAIR as well as the combination of BOXAIR with ERIC or REP could differentiate all 74 investigated Salmonella strains.

CONCLUSIONS

The combined use of RAPD and ERIC fingerprinting offers an excellent means of differentiating Salmonella strains.

SIGNIFICANCE AND IMPACT OF THE STUDY

The discrimination power of Salmonella molecular typing by combination of ERIC, REP and BOXAIR methods, or by combination of BOXAIR with ERIC or REP, is sufficient to determine genetic relationships for epidemiological purposes.

Genotyping of Salmonella strains isolated from ducks, their rearing and processing environments in Penang, Malaysia, using RAPD

Salmonella species are important foodborne pathogens that can cause illness and death in humans. The objective of this study was to determine the genetic relatedness of 115 Salmonella strains isolated from ducks and their environment using random amplified polymorphic deoxyribonucleic acid (RAPD). The analysis of Salmonella strains by RAPD produced DNA fingerprints of different sizes for differentiation purposes, and cluster analysis at a coefficient of 0.85 grouped the Salmonella strains into various clusters and singletons. S. Typhimurium were grouped into nine clusters and ten singletons, S. Hadar were grouped into seven clusters and nine singletons, S. Enteritidis were grouped into four clusters and five singletons, S. Braenderup were grouped into five clusters and four singletons, S. Albany were grouped into two clusters and seven singletons, and S. Derby were grouped into two clusters and four singletons at a coefficient of 0.85 with discriminatory index (D) ranging from 0.879 to 0.957. With the exception of S. Typhimurium strains which were grouped into three major groups (genotypes) by RAPD analysis, the rest were grouped into two major genotypes. RAPD was a useful genotyping tool for determining the genetic relatedness of the duck Salmonella strains. Comparison of the genetic relatedness among foodborne pathogens and their sources of isolation are important to trace their source and possibly the source of human infection.

Molecular techniques for detecting and typing of bacteria, advantages and application to foodborne pathogens isolated from ducks

In recent times, several foodborne pathogens have become important and a threat to public health. Surveillance studies have provided data and a better understanding into the existence and spread of foodborne pathogens. The application of molecular techniques for detecting and typing of foodborne pathogens in surveillance studies provide reliable epidemiological data for tracing the source of human infections. A wide range of molecular techniques (including pulsed field gel electrophoresis, multilocus sequence typing, random amplified polymorphism deoxyribonucleic acid, repetitive extragenic palindromic, deoxyribonucleic acid sequencing, multiplex polymerase chain reaction and many more) have been used for detecting, speciating, typing, classifying and/or characterizing foodborne pathogens of great significance to humans. Farm animals including chickens, cattle, sheep, goats and pigs, and others (such as domestic and wild animals) have been reported to be primary reservoirs for foodborne pathogens. The consumption of contaminated poultry meats or products has been considered to be the leading source of human foodborne infections. Ducks like other farm animals are important source of foodborne pathogens and have been implicated in some human foodborne illnesses and deaths. Nonetheless, few studies have been conducted to explore the potential of ducks in causing foodborne outbreaks, diseases and its consequences. This review highlights some common molecular techniques, their advantages and those that have been applied to pathogens isolated from ducks and their related sources.