Laboratory-acquired infections of Salmonella enterica serotype Typhi in South Africa: phenotypic and genotypic analysis of isolates

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dc.contributor.authorSmith, Anthony Marius
dc.contributor.authorSmouse, Shannon Lucrecia
dc.contributor.authorTau, Nomsa Pauline
dc.contributor.authorBamford, Colleen
dc.contributor.authorMoodley, Vineshree Mischka
dc.contributor.authorJacobs, Charlene
dc.contributor.authorMcCarthy, Kerrigan Mary
dc.contributor.authorLourens, Adré
dc.contributor.authorKeddy, Karen Helena
dc.contributor.authorGERMS-SA Surveillance Network
dc.date.accessioned2021-10-08T06:20:30Z
dc.date.available2021-10-08T06:20:30Z
dc.date.issued2017
dc.description.abstractBACKGROUND: Workers in clinical microbiology laboratories are exposed to a variety of pathogenic microorganisms. Salmonella species is among the most commonly reported bacterial causes of laboratory-acquired infections. We report on three cases of laboratory-acquired Salmonella enterica serotype Typhi (Salmonella Typhi) infection which occurred over the period 2012 to 2016 in South Africa. METHODS: Laboratory investigation included phenotypic and genotypic characterization of isolates. Phenotypic analysis included standard microbiological identification techniques, serotyping and antimicrobial susceptibility testing. Genotypic analysis included the molecular subtyping methodologies of pulsed-field gel electrophoresis analysis, multilocus sequence typing and whole-genome sequencing (WGS); with WGS data analysis including phylogenetic analysis based upon comparison of single nucleotide polymorphism profiles of isolates. RESULTS: All cases of laboratory-acquired infection were most likely the result of lapses in good laboratory practice and laboratory safety. The following critical issues were highlighted. There was misdiagnosis and misreporting of Salmonella Typhi as nontyphoidal Salmonella by a diagnostic laboratory, with associated public health implications. We highlight issues concerning the importance of accurate fluoroquinolone susceptibility testing and interpretation of results according to updated guidelines. We describe potential shortcomings of a single disk susceptibility screening test for fluoroquinolone susceptibility and suggest that confirmatory minimum inhibitory concentration testing should always be performed in cases of invasive Salmonella infections. These antimicrobial susceptibility testing issues resulted in inappropriate ciprofloxacin therapy which may have been responsible for failure in clearance of pathogen from patients. Salmonella Typhi capsular polysaccharide vaccine was not protective in one case, possibly secondarily to a faulty vaccine. CONCLUSIONS: Molecular subtyping of isolates proved effective to investigate the genetic relatedness of isolates. Molecular subtyping data interpreted together with epidemiological data allowed us to pinpoint the most likely sources for our cases of laboratory-acquired infection.
dc.identifier.apacitationSmith, A. M., Smouse, S. L., Tau, N. P., Bamford, C., Moodley, V. M., Jacobs, C., ... (2017). Laboratory-acquired infections of Salmonella enterica serotype Typhi in South Africa: phenotypic and genotypic analysis of isolates. <i>BMC Infectious Diseases</i>, 17(1), 174 - 177. http://hdl.handle.net/11427/34293en_ZA
dc.identifier.chicagocitationSmith, Anthony Marius, Shannon Lucrecia Smouse, Nomsa Pauline Tau, Colleen Bamford, Vineshree Mischka Moodley, Charlene Jacobs, Kerrigan Mary McCarthy, Adré Lourens, Karen Helena Keddy, and "Laboratory-acquired infections of Salmonella enterica serotype Typhi in South Africa: phenotypic and genotypic analysis of isolates." <i>BMC Infectious Diseases</i> 17, 1. (2017): 174 - 177. http://hdl.handle.net/11427/34293en_ZA
dc.identifier.citationSmith, A.M., Smouse, S.L., Tau, N.P., Bamford, C., Moodley, V.M., Jacobs, C., McCarthy, K.M. & Lourens, A. et al. 2017. Laboratory-acquired infections of Salmonella enterica serotype Typhi in South Africa: phenotypic and genotypic analysis of isolates. <i>BMC Infectious Diseases.</i> 17(1):174 - 177. http://hdl.handle.net/11427/34293en_ZA
dc.identifier.issn1471-2334
dc.identifier.ris TY - Journal Article AU - Smith, Anthony Marius AU - Smouse, Shannon Lucrecia AU - Tau, Nomsa Pauline AU - Bamford, Colleen AU - Moodley, Vineshree Mischka AU - Jacobs, Charlene AU - McCarthy, Kerrigan Mary AU - Lourens, Adré AU - Keddy, Karen Helena AU - GERMS-SA Surveillance Network AB - BACKGROUND: Workers in clinical microbiology laboratories are exposed to a variety of pathogenic microorganisms. Salmonella species is among the most commonly reported bacterial causes of laboratory-acquired infections. We report on three cases of laboratory-acquired Salmonella enterica serotype Typhi (Salmonella Typhi) infection which occurred over the period 2012 to 2016 in South Africa. METHODS: Laboratory investigation included phenotypic and genotypic characterization of isolates. Phenotypic analysis included standard microbiological identification techniques, serotyping and antimicrobial susceptibility testing. Genotypic analysis included the molecular subtyping methodologies of pulsed-field gel electrophoresis analysis, multilocus sequence typing and whole-genome sequencing (WGS); with WGS data analysis including phylogenetic analysis based upon comparison of single nucleotide polymorphism profiles of isolates. RESULTS: All cases of laboratory-acquired infection were most likely the result of lapses in good laboratory practice and laboratory safety. The following critical issues were highlighted. There was misdiagnosis and misreporting of Salmonella Typhi as nontyphoidal Salmonella by a diagnostic laboratory, with associated public health implications. We highlight issues concerning the importance of accurate fluoroquinolone susceptibility testing and interpretation of results according to updated guidelines. We describe potential shortcomings of a single disk susceptibility screening test for fluoroquinolone susceptibility and suggest that confirmatory minimum inhibitory concentration testing should always be performed in cases of invasive Salmonella infections. These antimicrobial susceptibility testing issues resulted in inappropriate ciprofloxacin therapy which may have been responsible for failure in clearance of pathogen from patients. Salmonella Typhi capsular polysaccharide vaccine was not protective in one case, possibly secondarily to a faulty vaccine. CONCLUSIONS: Molecular subtyping of isolates proved effective to investigate the genetic relatedness of isolates. Molecular subtyping data interpreted together with epidemiological data allowed us to pinpoint the most likely sources for our cases of laboratory-acquired infection. DA - 2017 DB - OpenUCT DP - University of Cape Town IS - 1 J1 - BMC Infectious Diseases LK - https://open.uct.ac.za PY - 2017 SM - 1471-2334 T1 - Laboratory-acquired infections of Salmonella enterica serotype Typhi in South Africa: phenotypic and genotypic analysis of isolates TI - Laboratory-acquired infections of Salmonella enterica serotype Typhi in South Africa: phenotypic and genotypic analysis of isolates UR - http://hdl.handle.net/11427/34293 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/34293
dc.identifier.vancouvercitationSmith AM, Smouse SL, Tau NP, Bamford C, Moodley VM, Jacobs C, et al. Laboratory-acquired infections of Salmonella enterica serotype Typhi in South Africa: phenotypic and genotypic analysis of isolates. BMC Infectious Diseases. 2017;17(1):174 - 177. http://hdl.handle.net/11427/34293.en_ZA
dc.language.isoeng
dc.publisher.departmentDivision of Medical Microbiology
dc.publisher.facultyFaculty of Health Sciences
dc.sourceBMC Infectious Diseases
dc.source.journalissue1
dc.source.journalvolume17
dc.source.pagination174 - 177
dc.source.urihttps://dx.doi.org/10.1186/s12879-017-2757-2
dc.subject.otherTyphi
dc.subject.otherLaboratory-acquired infection
dc.subject.otherSouth Africa
dc.subject.otherGenotyping
dc.subject.otherMolecular subtyping
dc.subject.otherPFGE
dc.subject.otherMLST
dc.subject.otherWhole-genome sequencing
dc.subject.otherWGS
dc.titleLaboratory-acquired infections of Salmonella enterica serotype Typhi in South Africa: phenotypic and genotypic analysis of isolates
dc.typeJournal Article
uct.type.publicationResearch
uct.type.resourceJournal Article
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