title: The discrimination of d-tartrate positive and d-tartrate negative S. enterica subsp. enterica serovar Paratyphi B isolated in Malaysia by phenotypic and genotypic methods.
abstract: Serotyping is not sufficient to differentiate between Salmonella species that cause paratyphoid fever from the strains that cause milder gastroenteritis as these organisms share the same serotype Salmonella Paratyphi B (S. Paratyphi B). Strains causing paratyphoid fever do not ferment d-tartrate and this key feature was used in this study to determine the prevalence of these strains among the collection of S. Paratyphi B strains isolated from patients in Malaysia. A total of 105 isolates of S. Paratyphi B were discriminated into d-tartrate positive (dT+) and d-tartrate negative (dT) variants by two lead acetate test protocols and multiplex PCR. The lead acetate test protocol 1 differed from protocol 2 by a lower inoculum size and different incubation conditions while the multiplex PCR utilized 2 sets of primers targeting the ATG start codon of the gene STM3356. Lead acetate protocol 1 discriminated 97.1% of the isolates as S. Paratyphi B dT+ and 2.9% as dT while test protocol 2 discriminated all the isolates as S. Paratyphi B dT+. The multiplex PCR test identified all 105 isolates as S. Paratyphi B dT+ strains. The concordance of the lead acetate test relative to that of multiplex PCR was 97.7% and 100% for protocol 1 and 2 respectively. This study showed that S. Paratyphi B dT+ is a common causative agent of gastroenteritis in Malaysia while paratyphoid fever appears to be relatively uncommon. Multiplex PCR was shown to be a simpler, more rapid and reliable method to discriminate S. Paratyphi B than the phenotypic lead acetate test.
authors.affiliation: Bacteriology Unit, Institute for Medical Research, Kuala Lumpur. norazah@imr.gov.my
authors.forename: Norazah
authors.initials: N
authors.lastname: Ahmad
authors.forename: Shirley Tang Gee
authors.initials: ST
authors.lastname: Hoon
authors.forename: Mohamed Kamel Abd
authors.initials: MK
authors.lastname: Ghani
authors.forename: Koh Yin
authors.initials: KY
authors.lastname: Tee
mesh_terms: D004269:DNA, Bacterial / Q000032:analysis; D005243:Feces / Q000382:microbiology; D005285:Fermentation; D005838:Genotype; D006801:Humans; D008296:Malaysia; D009942:Organometallic Compounds; D010284:Paratyphoid Fever / Q000175:diagnosis / Q000382:microbiology*; D010641:Phenotype; D016133:Polymerase Chain Reaction / Q000379:methods; D012484:Salmonella paratyphi B / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D012703:Serotyping; D013644:Tartrates / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D009942:Organometallic Compounds; D013644:Tartrates; C008261:lead acetate; C029768:tartaric acid