Epidemiology and Molecular Typing of Pregnancy-Associated Listeriosis Cases in Lombardy, Italy, over a 10-Year Period (2005-2014)

Infect Dis Obstet Gynecol. 2017:2017:6479121. doi: 10.1155/2017/6479121. Epub 2017 Mar 19.

Abstract

In developed countries, pregnancy-related listeriosis accounts for 20-43% of total invasive listeriosis. This work describes the first pregnancy-related listeriosis survey in Italy based on two data sources, that is, mandatory notification system and regional laboratory-based network. Out of 610 listeriosis cases reported over a 10-year period, 40 were pregnancy-related (6.6%). Among these, 29 pregnancy-related isolates were available and have been analysed with serotyping, Pulsed-Field Gel Electrophoresis, and Multi-Virulence-Locus Sequence Typing. No maternal fatality was recorded, but 11 (29.7%) pregnancies resulted in a foetal death, a miscarriage, or a birth of a foetus dying immediately after birth. The average incidence of pregnancy-related listeriosis was 4.3 cases per 100000 births, and the proportion of pregnancy-associated listeriosis among ethnic minorities was significantly higher compared to the general population (30.0% versus 3.5%, P < 0.01). L. monocytogenes isolates belonged to serotypes 1/2a, 1/2b, and 4b, with the latter significantly more prevalent among pregnancy-related isolates. Twenty different pulsotypes were distinguished and 16 out of the 29 isolates were classified into seven clusters. A total of 16 virulence types (VTs) were identified. Five VTs accounted for 45% of the total cases and coincided with those of previously described Epidemic Clones (ECs) of L. monocytogenes.

MeSH terms

  • DNA, Bacterial / genetics
  • Disease Outbreaks
  • Electrophoresis, Gel, Pulsed-Field / methods
  • Female
  • Food Microbiology
  • Genotype
  • Humans
  • Incidence
  • Infant, Newborn
  • Italy / epidemiology
  • Listeria monocytogenes / genetics
  • Listeria monocytogenes / isolation & purification*
  • Listeria monocytogenes / pathogenicity
  • Listeriosis / epidemiology*
  • Listeriosis / genetics
  • Listeriosis / microbiology
  • Molecular Epidemiology
  • Molecular Typing / methods
  • Multilocus Sequence Typing
  • Pregnancy
  • Pregnancy Complications, Infectious / epidemiology*
  • Pregnancy Complications, Infectious / genetics
  • Pregnancy Complications, Infectious / microbiology
  • Virulence Factors / genetics

Substances

  • DNA, Bacterial
  • Virulence Factors