Neonatal listeriosis during a countrywide epidemic in South Africa: A tertiary hospital's experience.

BACKGROUND: A countrywide epidemic of Listeria monocytogenes (LM) in South Africa began in the first quarter of 2017, rapidly becoming the world's largest LM outbreak to date.

METHODS: We describe the clinical course of neonates with culture-confirmed LM infection admitted to a tertiary neonatal unit at Tygerberg Hospital, Cape Town (1 January 2017 - 31 January 2018). Current epidemic LM cases were compared with a historical cohort of sporadic neonatal LM cases at our institution (2006 - 2016). The global literature on epidemic neonatal LM outbreaks (1 January 1978 - 31 December 2017) was reviewed.

RESULTS: Twelve neonates (median gestational age 35 weeks, median birth weight 2 020 g) were treated for confirmed LM bacteraemia in 2017/18, presenting at a median age of 0.5 days. In 5 cases, neurolisteriosis was suspected. Three neonates died (25.0%) v. 8/13 neonatal deaths (61.6%) in the sporadic listeriosis cohort (2006 - 2016) (p=0.075). The institution's neonatal LM infection incidence increased significantly in 2017 from a historical rate of 0.17/1 000 live births to 1.4/1 000 (p<0.001). During the current LM epidemic, the crude neonatal fatality rate exceeded the average calculated global epidemic neonatal LM mortality (3/12 (25.0%) v. 50/290 (17.2%); p=0.448). Possible factors contributing to the high mortality rate in this epidemic LM neonatal cohort may include more virulent disease associated with sequence type 6 and the predominance of early-onset disease.

CONCLUSIONS: Epidemic neonatal listeriosis at Tygerberg Hospital was associated with a predominance of bacteraemic, early-onset disease. Listeriosis-associated mortality rates were higher than previously published, but lower than the rate in a historical institutional cohort.