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Listeriosis in Pregnancy. Max Brinsmead PhD FRANZCOG December 2010. Listeriosis. Caused by Listeria monocytogenes A motile Gram-positive bacterium Relatively ubiquitous in the environment Found in 1 – 15% of human faeces Infection in animals is common Human infection is rare except:
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Listeriosis in Pregnancy Max Brinsmead PhD FRANZCOG December 2010
Listeriosis • Caused by Listeriamonocytogenes • A motile Gram-positive bacterium • Relatively ubiquitous in the environment • Found in 1 – 15% of human faeces • Infection in animals is common • Human infection is rare except: • When immunocompromised • Pregnant • Elderly • Newborn • In 2004 - 05 there were 3 cases per million population in the US • But 30% of these were in pregnant women
Listeriosis Infection • Begins with ingestion of contaminated food • Will be phagocytosed by GI tract cells • And thereafter continues a “hidden” life within cells • Spread by direct cell-to-cell transfer • Not exposed to humoral antibodies • Controlled only by cell-mediated immunity • Which is reduced in pregnancy • So pregnant women have a 20-fold increased susceptibility to this infection • Risk is further enhanced by... • Splenectomy • HIV infection • Steroids or immunosupressant drugs • Diabetes
Listeriosis in Pregnancy • Fewer than 10 per 100,000 women • Infection may be asymptomatic • But the following symptoms also occur: • Fever (38.2 to 41.20 C and mean of 38.9) • Malaise • Flu-like symptoms such as headache and myalgia • Rarely CNS infection with meningitis or abscess • Transmission risk to the fetus about 50% • Untreated the risk of fetal death is 20 – 30% • Pathognemonic finding is widespread abscesses & granulomas in the fetus (rare)
Diagnosis • Clinical diagnosis requires a high index of suspicion • Culture from blood, amniotic fluid or CSF is required • Gram stain useful in only 33% of cases because the organism is intracellular and can resemble pneumococci, diptheroids and Haemophilus • WCC may be raised but often within the normal range for pregnancy
Treatment • Use Ampicillin 2G every 6 – 8 hrs • This high dose is recommended in order to cross to the amniotic fluid and membranes in sufficiently high concentrations • Gentamicin is said to be synergistic but not recommended in pregnancy (nephrooto toxic) • For penicillin allergy use Bactrim/Septrim • Sometimes Vancomycin • Maybe Erythromycin but placental passage is poor
Prevention • Aims to reduce a pregnant woman’s exposure to possible contaminated food sources • Authorities recommend dietary advice to ALL pregnant women • But this has never been tested by RCT • Most cases are sporadic and the source is rarely identified • Food sources have been identified either by outbreaks or microbiological examination
Typical Pregnancy Advice “Listeria is a very rare infection that is mild in a mother but can be fatal to the baby in utero. You should NOT eat the following: • Unpasteurised milk products esp. Soft cheeses, included feta, Brie, Camembert and ethnic-style cheeses. (Hard cheeses, pasteurised, cottage & cheese spreads are okay) • Raw seafood • Uncooked meats and vegetables • Cold-stored cooked meats and pates, • Milk products stored at >40 C • Beware of cross contamination from these sources • Wash all fruit and vegetables • Cook foods at recommended temperatures”
