title: Three Epidemics of Invasive Multidrug-Resistant Salmonella Bloodstream Infection in Blantyre, Malawi, 1998-2014.
abstract: BACKGROUND
  The Malawi Liverpool Wellcome Trust Clinical Research Programme (MLW) has routinely collected specimens for blood culture from febrile patients, and cerebrospinal fluid from patients with suspected meningitis, presenting to Queen Elizabeth Central Hospital (QECH), Blantyre, Malawi, since 1998.
  
  
  METHODS
  We present bloodstream infection (BSI) and meningitis surveillance data from 1998 to 2014. Automated blood culture, manual speciation, serotyping, and antimicrobial susceptibility testing were performed at MLW. Population data for minimum-incidence estimates in urban Blantyre were drawn from published estimates.
  
  
  RESULTS
  Between 1998 and 2014, 167,028 blood cultures were taken from adult and pediatric medical patients presenting to QECH; Salmonella Typhi was isolated on 2054 occasions (1.2%) and nontyphoidal Salmonella (NTS) serovars were isolated 10,139 times (6.1%), of which 8017 (79.1%) were Salmonella Typhimurium and 1608 (15.8%) were Salmonella Enteritidis. There were 392 cases of NTS meningitis and 9 cases of Salmonella Typhi meningitis. There have been 3 epidemics of Salmonella BSI in Blantyre; Salmonella Enteritidis from 1999 to 2002, Salmonella Typhimurium from 2002 to 2008, and Salmonella Typhi, which began in 2011 and was ongoing in 2014. Multidrug resistance has emerged in all 3 serovars and is seen in the overwhelming majority of isolates, while resistance to third-generation cephalosporins and fluoroquinolones is currently uncommon but has been identified.
  
  
  CONCLUSIONS
  Invasive Salmonella disease in Malawi is dynamic and not clearly attributable to a single risk factor, although all 3 epidemics were associated with multidrug resistance. To inform nonvaccine and vaccine interventions, reservoirs of disease and modes of transmission require further investigation.
authors.affiliation: Liverpool School of Tropical Medicine, United Kingdom Malawi Liverpool Wellcome Trust Clinical Research Programme.
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Feasey
authors.affiliation: Malawi Liverpool Wellcome Trust Clinical Research Programme.
authors.forename: Clemens
authors.initials: C
authors.lastname: Masesa
authors.affiliation: Malawi Liverpool Wellcome Trust Clinical Research Programme.
authors.forename: Chikondi
authors.initials: C
authors.lastname: Jassi
authors.affiliation: Liverpool School of Tropical Medicine, United Kingdom.
authors.forename: E Brian
authors.initials: EB
authors.lastname: Faragher
authors.affiliation: University of Malawi College of Medicine, Blantyre.
authors.forename: Jane
authors.initials: J
authors.lastname: Mallewa
authors.affiliation: University of Malawi College of Medicine, Blantyre.
authors.forename: Macpherson
authors.initials: M
authors.lastname: Mallewa
authors.affiliation: The Jenner Institute, Nuffield Department of Medicine, University of Oxford Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge.
authors.forename: Calman A
authors.initials: CA
authors.lastname: MacLennan
authors.affiliation: University of Malawi College of Medicine, Blantyre.
authors.forename: Chisomo
authors.initials: C
authors.lastname: Msefula
authors.affiliation: Malawi Liverpool Wellcome Trust Clinical Research Programme Division of Infection and Immunity, University College London.
authors.forename: Robert S
authors.initials: RS
authors.lastname: Heyderman
authors.affiliation: Malawi Liverpool Wellcome Trust Clinical Research Programme Institute for Infection and Global Health, University of Liverpool, United Kingdom.
authors.forename: Melita A
authors.initials: MA
authors.lastname: Gordon
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D016470:Bacteremia / Q000453:epidemiology* / Q000382:microbiology*; D002511:Cephalosporins / Q000494:pharmacology; D002648:Child; D002675:Child, Preschool; D024901:Drug Resistance, Multiple, Bacterial; D058872:Epidemics; D062665:Epidemiological Monitoring; D005260:Female; D024841:Fluoroquinolones / Q000494:pharmacology; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008295:Malawi / Q000453:epidemiology; D008297:Male; D016920:Meningitis, Bacterial / Q000453:epidemiology* / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D012307:Risk Factors; D012480:Salmonella Infections / Q000453:epidemiology* / Q000209:etiology / Q000382:microbiology*; D019779:Salmonella enterica / Q000145:classification / Q000187:drug effects / Q000302:isolation & purification*; D012477:Salmonella enteritidis / Q000187:drug effects / Q000302:isolation & purification; D012485:Salmonella typhi / Q000187:drug effects / Q000302:isolation & purification; D012486:Salmonella typhimurium / Q000187:drug effects / Q000302:isolation & purification; D012703:Serotyping; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D024841:Fluoroquinolones
keywords: Africa; Salmonella; bloodstream infection; multi-drug resistance