Temperate phages in Salmonella enterica serovar Typhimurium: Implications for epidemiology

Mmolawa, Princess T.; Willmore, Rina; Thomas, Connor; Heuzenroeder, Michael W.

doi:10.1078/1438-4221-00178

Cited by 36 publications

(40 citation statements)

References 35 publications

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“…Southern hybridization studies have suggested that these bacteriophages are present in a number of serovar Typhimurium phage types as well as other S. enterica subsp. enterica serovars, including Enteritidis, Virchow, Heidelberg, and Hadar (13,31). Based on the widespread nature of these phages, we used this sequence data to design a number of primer sets to analyze sequence variations of prophage loci.…”

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confidence: 99%

Discrimination within Phenotypically Closely Related Definitive Types of Salmonella enterica Serovar Typhimurium by the Multiple Amplification of Phage Locus Typing Technique

Ross

Heuzenroeder

2005

J Clin Microbiol

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Multilocus sequence typing (MLST) is a relatively new high-resolution typing system employed for epidemiological studies of bacteria, including Salmonella. Discrimination based on MLST of housekeeping genes may be problematical, due to the high identity of gene sequences of closely related Salmonella species. The presence of genomic sequences derived from stable temperate phages in Salmonella offers an alternative for MLST of Salmonella. We have used MLST of prophage loci in Salmonella enterica serovar Typhimurium to discriminate closely related isolates of serovar Typhimurium. We have compared these results to MLST of five housekeeping genes, as well as pulsed-field gel electrophoresis (PFGE). The presence or absence of prophage loci in the 73 serovar Typhimurium isolates tested, as well as allelic variation as detected by sequencing, provided greater discrimination between isolates than either MLST of housekeeping genes or PFGE. Amplification of prophage loci alone separated serovar Typhimurium isolates into 27 groups comprising multiple isolates or individual strains. Sequencing of isolates found within the clusters separated isolates even further. By contrast, PFGE could only divide the 73 isolates into five distinct groups. MLST using housekeeping genes did not provide any significant separation of isolates in comparison to amplification or MLST of prophage loci. The results demonstrate that the amplification and sequencing of prophage loci provides a high-resolution, objective method for the discrimination of closely related isolates of serovar Typhimurium. It is proposed that multiple amplification of phage locus typing may provide sufficient discrimination for epidemiological purposes without recourse to MLST.

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confidence: 99%

Discrimination within Phenotypically Closely Related Definitive Types of Salmonella enterica Serovar Typhimurium by the Multiple Amplification of Phage Locus Typing Technique

Ross

Heuzenroeder

2005

J Clin Microbiol

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“…Evaluation of the SSH data in light of the newly discovered ST160 genome sequence suggested that DT160 harboured two prophages that were not present in the genome of LT2, ST160 and ST64B. Bacteriophage ST64B was initially isolated and characterized simultaneously with ST64T from S. Typhimurium DT64 [21]. ST64B and ST64T have a similar outward appearance and their genomes have a similar overall architecture, but individual gene sequences share no significant identity.…”

Section: Discussionmentioning

confidence: 99%

“…ST64T is capable of infecting a variety of different Salmonella serovars. It can mediate phage-type conversion in lysogenized strains and can undergo generalized transduction, packaging and transfer of Salmonella DNA between host strains [21]. Bacteriophage SE1 was originally purified from an S. Enteritidis strain isolated from a hospitalized patient in Spain [26].…”

Section: Discussionmentioning

confidence: 99%

The evolution and distribution of phage ST160 withinSalmonella entericaserotype Typhimurium

et al. 2010

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SUMMARYSalmonellosis is an internationally important disease of mammals and birds. Unique epidemics in New Zealand in the recent past include two Salmonella serovars : Salmonella enterica subsp. enterica serovar Typhimurium definitive type (DT) 160 (S. Typhimurium DT160) and S. Brandenburg. Although not a major threat internationally, in New Zealand S. Typhimurium DT160 has been the most common serovar isolated from humans, and continues to cause significant losses in wildlife. We have identified DNA differences between the first New Zealand isolate of S. Typhimurium DT160 and the genome-sequenced strain, S. Typhimurium LT2. All the differences could be accounted for in one cryptic phage ST64B, and one novel P22-like phage, ST160. The majority of the ST160 genome is almost identical to phage SE1 but has two regions not found in SE1 which are identical to the P22-like phage ST64T, suggesting that ST160 evolved from SE1 via two recombination events with ST64T. All of the New Zealand isolates of DT160 were identical indicating the clonal spread of this particular Salmonella. Some overseas isolates of S. Typhimurium DT160 differed from the New Zealand strain and contained SE1 phage rather than ST160. ST160 was also identified in New Zealand isolates of S. Typhimurium DT74 and S. Typhimurium RDNC-April06 and in S. Typhimurium DT160 isolates from the USA. The emergence of S. Typhimurium DT160 as a significant pathogen in New Zealand is postulated to have occurred due to the sensitivity of the Salmonella strains to the ST160 phage when S. Typhimurium DT160 first arrived.

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“…The predominance of one particular phage type within a serovar in a geographical and/or temporal region often reduces the effectiveness of this method in discriminating between outbreak strains and epidemiologically unrelated isolates. Furthermore, phage-type conversion due to acquisition of DNA such as plasmids or temperate phages complicates interpretation of typing results [1,[10][11][12][13]. Molecular methods have been introduced to enhance the discrimination of isolates in epidemiological studies ; these include plasmid profiling, chromosomal fingerprinting, Southern hybridization and restriction fragment length polymorphism (RFLP).…”

Section: Introductionmentioning

confidence: 99%

Use of AFLP and PFGE to discriminate between Salmonella enterica serovar Typhimurium DT126 isolates from separate food-related outbreaks in Australia

Ross

Heuzenroeder

2005

Epidemiol. Infect.

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SUMMARYIn 2001 Salmonella enterica serovar Typhimurium definitive phage-type (DT) 126 was isolated at higher frequency in Australia compared to other S. Typhimurium phage types and in comparison to previous years. Associated with this increase was the implication of this phage type in a number of food-related outbreaks. We compared fluorescent amplified fragment length polymorphism (FAFLP) to pulsed-field gel electrophoresis (PFGE), the current ' gold standard ' for molecular typing of Salmonella for the discrimination between outbreak-associated isolates and epidemiologically unrelated DT126 strains. FAFLP showed a greater ability to discriminate between isolates than PFGE, with 16 groups of clusters or individual isolates with <90 % similarity to each other compared to three groups as determined by PFGE. Both methods were able to discriminate between isolates from two separate outbreaks in South Australia and isolates associated with an outbreak at a restaurant in New South Wales. The resolving power of both methods was not sufficient to separate all epidemiologically unrelated DT126 isolates from the outbreak isolates. We conclude that amplified fragment length polymorphism is a useful tool to assist in the discrimination of S. Typhimurium DT126 isolates.

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Temperate phages in Salmonella enterica serovar Typhimurium: Implications for epidemiology

Cited by 36 publications

References 35 publications

Discrimination within Phenotypically Closely Related Definitive Types of Salmonella enterica Serovar Typhimurium by the Multiple Amplification of Phage Locus Typing Technique

Discrimination within Phenotypically Closely Related Definitive Types of Salmonella enterica Serovar Typhimurium by the Multiple Amplification of Phage Locus Typing Technique

The evolution and distribution of phage ST160 withinSalmonella entericaserotype Typhimurium

Use of AFLP and PFGE to discriminate between Salmonella enterica serovar Typhimurium DT126 isolates from separate food-related outbreaks in Australia

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