Pregnancy-associated Listeriosis Research Articles

Invasive Listeriosis in the Foodborne Diseases Active Surveillance Network (FoodNet), 2004–2009: Further Targeted Prevention Needed for Higher-Risk Groups

Listeriosis can cause severe disease, especially in fetuses, neonates, older adults, and persons with certain immunocompromising and chronic conditions. We summarize US population-based surveillance data for invasive listeriosis from 2004 through 2009. We analyzed Foodborne Diseases Active Surveillance Network (FoodNet) data for patients with Listeria monocytogenes isolated from normally sterile sites. We describe the epidemiology of listeriosis, estimate overall and specific incidence rates, and compare pregnancy-associated and nonpregnancy-associated listeriosis by age and ethnicity. A total of 762 listeriosis cases were identified during the 6-year reporting period, including 126 pregnancy-associated cases (17%), 234 nonpregnancy-associated cases(31%) in patients aged <65 years, and 400 nonpregnancy-associated cases (53%) in patients aged ≥ 65 years. Eighteen percent of all cases were fatal. Meningitis was diagnosed in 44% of neonates. For 2004-2009, the overall annual incidence of listeriosis varied from 0.25 to 0.32 cases per 100,000 population. Among Hispanic women, the crude incidence of pregnancy-associated listeriosis increased from 5.09 to 12.37 cases per 100,000 for the periods of 2004-2006 and 2007-2009, respectively; among non-Hispanic women, pregnancy-associated listeriosis increased from 1.74 to 2.80 cases per 100,000 for the same periods. Incidence rates of nonpregnancy-associated listeriosis in patients aged ≥ 65 years were 4-5 times greater than overall rates annually. Overall listeriosis incidence did not change significantly from 2004 through 2009. Further targeted prevention is needed, including food safety education and messaging (eg, avoiding Mexican-style cheese during pregnancy). Effective prevention among pregnant women, especially Hispanics, and older adults would substantially affect overall rates.

Enterocin CRL35 InhibitsListeria monocytogenesin a Murine Model

Listeria monocytogenes is a foodborne pathogen causative of opportunistic infections. Listeriosis is associated with severe infections in pregnant women causing abortion or neonatal listeriosis. An alternative to antibiotics are safe novel bacteriocins peptides such as enterocin CRL35 with strong antilisterial activity produced by Enterococcus mundtii CRL35. In the present paper, our goal is to study the effectiveness of this peptide and the producer strain in a murine model of pregnancy-associated listeriosis. A single dose of 5×10(9) colony-forming unit of L. monocytogenes FBUNT (Faculty of Biochemistry-University of Tucumán) resulted in translocation of pathogen to liver and spleen of BALB/c pregnant mice. The maximum level of Listeria was observed on day 3 postinfection. Interestingly, the intragastric administration of enterocin CRL35 significantly reduced the translocation of the pathogen to vital organs. On the other hand, the preadministration of E. mundtii CRL35 slightly inhibited this translocation. Listeria infection caused a significant increase in polymorphonuclear leukocytes at day 3 postinfection compared to the noninfected group. This value was reduced after the administration of enterocin CRL35. No significant changes were observed in either white blood cells or lymphocytes counts. Based on the data presented in the present work enterocin CRL35 would be a promising alternative for the prevention of Listeria infections.

Pregnancy-associated listeriosis

Infection by Listeria monocytogenes in pregnant women may result in fetal loss or invasive disease in the newborn. We examined listeriosis cases reported through the U.S. Listeria Initiative during 2004-2007. Cases were classified as pregnancy-associated if illness occurred in a pregnant woman or an infant aged <28 days. Of 758 reported Listeria cases, 128 (16.9%) were pregnancy-associated. Maternal infection resulted in four neonatal deaths and 26 (20.3%) fetal losses. Invasive illnesses in newborns (n=85) were meningitis (32.9%) and sepsis (36.5%). Pregnant women with Listeria were more likely to report Hispanic ethnicity (52.8% vs. 25.6%, respectively; OR 3.3 95% CI 2.2-4.8) than mothers giving live birth in the USA during 2005 and were more likely to report consumption of Mexican-style cheese (OR 2.6, 95% CI 1.6-4.2) than were non-pregnant patients with Listeria infection. Pregnant woman comprised a considerable proportion of reported listeriosis cases. Further declines in pregnancy-associated listeriosis will require education about avoiding high-risk foods, and continued regulatory and industry efforts to decrease Listeria in foods.

Murine model of pregnancy-associated Listeria monocytogenes infection

Listeria monocytogenes has been recognized as a significant pathogen, occurring worldwide, capable of causing animal and human infections. In its most severe form, listeriosis is an invasive disease that affects immunocompromised patients. Additionally, pregnant women represent a high-risk group for L. monocytogenes infection. Abortion, stillbirth or severe neonatal infection can be the serious outcome of such an infection. In an experimental murine model of pregnancy-associated listeriosis we studied the impact of L. monocytogenes on the maternal immune response and pregnancy outcome. In comparison to virgin animals, pregnant mice mounted lower levels of protective cytokines and were inable to eliminate the pathogen. The impaired maternal immune response that has been found both on the systemic and local level, faciliated bacterial multiplication in the liver, placenta and ultimately in the fetal tissues. This resulted in severe necrotizing hemorrhagic hepatitis and Listeria-induced placental necrosis, increasing the incidence of postimplantation loss and poor pregnancy outcome.

Effects of pregnancy-associated Listeria monocytogenes infection: necrotizing hepatitis due to impaired maternal immune response and significantly increased abortion rate.

The impact of L. monocytogenes infection on maternal immune responses as well as on the outcome of pregnancy was studied in a murine model of pregnancy-associated listeriosis. Mice infected i.v. with L. monocytogenes at day 15 of pregnancy showed a significantly impaired bacterial elimination, which resulted in a severe necrotizing hemorrhagic hepatitis. The aggravated course of the infection could be attributed to a suppressed transcription and production of anti-listerial, pro-inflammatory cytokines and chemokines, namely interferon-gamma, tumor necrosis factor, interleukin-12p40, inducible nitric oxide synthase, murine monokine induced by interferon-gamma, and interferon-gamma-inducible protein-10. In addition, listeriosis significantly increased the abortion rate. Infection of the placenta and fetuses was characterized by placental and fetal necrosis with unrestricted bacterial multiplication. A weak transcription of anti-listerial cytokines in the placenta in the absence of a cellular immune response could not prevent the fatal outcome of pregnancy-associated listeriosis.