Neonatal Listeriosis and The Importance of Body Surface Cultures

Introduction

Listeria monocytogenes (Lm) is a gram-positive bacillus which causes neonatal listeriosis (NL). NL is caused by vertical transmission (transplacental, ascending or birth canal related) or less frequently by nosocomial infection. In healthy people, Lm infections may be asymptomatic or cause unspecific flu-like or gastrointestinal symptoms. However, in immunocompromised patients including elderly people, pregnant women or neonates, Lm may cause fatal infections. Mortality can be high (up to 45%), as can be the rate of neurologic complications (Siegman-Igra Y et al., Emerg. Infect. Dis. 2002; 8: 305–310).

In 2014, the European Centre for Disease Prevention and Control (ECDC) reported 2.194 listeriosis cases (case rate 0.6/100.000 population) with highest rates in infants below one year of age (case rate 2.8/100.000 population) observing rising tendency. In that year, 161 of the cases (all age groups) were declared in Spain (case rate 1.2/100.000 population) (Annual Epidemiological Report - Listeria, ECDC 2016). On the other hand, spontaneous abortions and stillbirths wrongly not related with Lm may underestimate real prevalence. In neonates, Lm can cause 2 different patterns of disease. First, an early-onset disease due to vertical infection (serotypes 1a, 1b 4b) associated with premature birth, meconium staining of amniotic fluid (MSAF) and sepsis. Second, a late-onset disease due to vertical or nosocomial infection (serotypes 4b) and most common in term babies causing meningitis.

Microbiological detection can be challenging as the poor specificity of blood cultures and Cerebral Spinal Fluid (CSF) cultures. Clinical guidelines for neonatal early-onset sepsis (EOS) evaluation do not recommend or pay little attention to body surface cultures (BSC) (Centers for Disease Control and Prevention. MMWR 2010; 59: 1–23), (Polin R et al., Pediatrics 2012; 129: 1006–1015). In cases of suspected EOS we perform BSC routinely in our neonatal tertiary care unit. In this report we evaluate NL biological testing with focus on BSC.