A Bacteriophage Cocktail Significantly Reduces Listeria Monocytogenes without Deleterious Impact on the Commensal Gut Microbiota under Simulated Gastrointestinal Conditions

In this study, we examined the effect of a bacteriophage cocktail (tentatively designated as the Foodborne Outbreak Pill (FOP)) on the levels of Listeria monocytogenes in simulated small intestine, large intestine, and Caco-2 model systems. We found that FOP survival during simulated passage of the upper gastrointestinal was dependent on stomach pH, and that FOP robustly inhibited L. monocytogenes levels with effectiveness comparable to antibiotic treatment (ampicillin) under simulated ilium and colon conditions. The FOP did not inhibit the commensal bacteria, whereas ampicillin treatment led to dysbiosis-like conditions. The FOP was also more effective than an antibiotic in protecting Caco-2 cells from adhesion and invasion by L. monocytogenes (5-log reduction vs. 1-log reduction) while not triggering an inflammatory response. Our data suggested that the FOP may provide a robust protection against L. monocytogenes should the bacterium enter the human gastrointestinal tract (e.g., by consumption of contaminated food), without deleterious impact on the commensal bacteria.

[Abdominal pain in a man with an endovascular aortic prosthesis]

A 79-year-old man with an abdominal aorta aneurysm (AAA) with endovascular repair presented with abdominal pain and inflammation. Although the initial work-up was in favour of an idiopathic inflammatory AAA, FDG-PET imaging showed atypical irregular uptake. Per-operative assessment and culture of pus matter revealed infection by Listeria monocytogenes. Atypical findings on imaging of aortic wall inflammation should alarm the clinician of an infectious aetiology.

Internalin AB-expressing recombinant Lactobacillus casei protects Caco-2 cells from Listeria monocytogenes-induced damages under simulated intestinal conditions

Background

Listeria monocytogenes is an intracellular foodborne pathogen that employs a number of strategies to survive challenging gastrointestinal conditions. It proliferates in the gut and subsequently causes listeriosis in high-risk individuals. Therefore, inhibition of its adherence to the intestinal receptors is crucial in controlling its infection. In this study, the effect of our previously developed recombinant Lactobacillus casei strain expressing invasion protein, Internalin AB of L. monocytogenes (Lbc^InlAB) on epithelial infection processes of the latter under simulated intestinal conditions was investigated.

Materials and methods

The confluent Caco-2 cell monolayer was pre-exposed to different L. casei strains at a multiplicity of exposure (MOE) of 10 for various periods before infection with L. monocytogenes at a multiplicity of infection (MOI) of 10 under simulated intestinal conditions. Subsequently, L. monocytogenes adhesion, invasion, and translocation, cytotoxicity and impact on tight junction integrity of the Caco-2 cells were analyzed.

Results

Under the simulated gastrointestinal condition, Lbc^InlAB showed a significant increase (p<0.0001) in adherence to, invasion and translocation through the Caco-2 cells when compared with the wild type strain. Although Lbc^InlAB strain exhibited enhanced inhibition of L. monocytogenes, it was not able to displace L. monocytogenes cells already attached to the monolayer. Additionally, pre-exposure to Lbc^InlAB reduced L. monocytogenes-mediated cytotoxicity and protected the tight junction barrier function.

Conclusion

The recombinant L. casei expressing InlAB shows potential for use as a prophylactic intervention strategy for targeted control of L. monocytogenes during the intestinal phase of infection.

Trends in US Hospital Stays for Listeriosis in Infants

BACKGROUND AND OBJECTIVES

Although listeriosis is rare in infants, it is common for young infants with suspected serious bacterial infection to be treated empirically with agents selected, in part, for their activity against Listeria monocytogenes. Our objectives were to describe the recent epidemiology of hospital discharges for listeriosis among infants in the United States and to precisely estimate the incidence of listeriosis according to infant age and meningitis status.

METHODS

We generated national estimates for listeriosis discharges in each of the 6 years for which samples were available in the Kids' Inpatient Database during the period 1997-2012. We used random-effects models to pool descriptive information and population rates across study years.

RESULTS

The cumulative number of US hospital discharges for listeriosis in infants was 344 (95% confidence interval [CI]: 290-397) over the 6 study years. The pooled annual incidence rate in infants (per 100,000 births) was 1.41 (95% CI: 1.01-1.80) after accounting for marked fluctuation in annual rates (range: 0.66-1.86; I2=79.3%). Discharges for listeriosis without meningitis were particularly rare after the first week of life. Our models predicted only 2.7 (95% CI: 1.1-4.2) and 1.8 (95% CI: 0.0-3.6) such discharges per year in infants admitted at ages 7 to 28 days and 29 to 364 days, respectively.

CONCLUSIONS

From the perspective of providing coverage against listeriosis, the routine practice of including ampicillin in the empirical treatment of febrile infants should be reevaluated for those older than 1 week without clinical evidence of meningitis.

Listeria monocytogenes infection in ruminants: Is there a link to the environment, food and human health? A review

Listeria (L.) monocytogenes is widely distributed in the environment, but also has the ability to cause serious invasive disease in ruminants and humans. This review provides an overview of listeriosis in ruminants and discusses our insufficient understanding of reservoirs and possible cycling ofL. monocytogenes between animal and human hosts, food and the environment. It indicates gaps in our knowledge of the role of genetic subtypes in L. monocytogenes ecology and virulence as well as risk factors, in vivo diagnostics and pathogenesis of listeriosis in ruminants. Filling these gaps will contribute to improving the control of L. monocytogenes and enhancing disease prevention. As the prevalence of listeriosis in ruminants in Switzerland is likely to be underestimated, propositions concerning improvement options for surveillance of listeriosis in ruminants are provided.

Listeria Monocytogenes: an uncommon pathogen of cervical necrotizing fasciitis

The aim of this paper is to present a unique case of neck-necrotizing fasciitis caused by Listeria Monocytogenes in a young woman, successfully treated by surgery and IV antibiotic therapy. Necrotizing fasciitis is a rare, rapidly progressing and potentially life-threatening infection that infrequently occurs in the head and neck region. Pathogens involved in necrotizing fasciitis are heterogeneous and include aerobic and anaerobic bacteria. To the best of our knowledge, this is the only case of neck necrotizing fasciitis caused by Listeria Monocytogenes studied in literature so far.

[A clinical analysis of 16 patients with maternal listeriosis]

OBJECTIVE

To summarize the clinical characteristics and outcome of maternal listeriosis so as to improve the understanding of disease and the level of diagnosis and treatment.

METHODS

Retrospectively, 16 cases of maternal listeriosis, who were treated at Peking Union Medical College Hospital between March 2007 and December 2014 were reviewed. Maternal listeriosis is defined when a pregnant woman presents with symptoms as listeriosis, meanwhile Listeria monocytogenes is isolated from sterile tissue or peripheral blood, or from a non-sterile site (uterus swab) or pathological evidence of chorioamnionitis. The neonatal listeriosis is diagnosed as acute listeria sepsis.

RESULTS

The mean age of these 16 patients was (30.0 ± 3.9) years old. There were 1, 8, 7 patients with listeriosis diagnosed in the first, second and third trimester of pregnancy, respectively. All had an acute onset of illness (≤ 2 weeks), the median time from onset to presentation was 2.5 days. Clinical manifestations included fever (93.8%, 15/16), leukocytosis (78.6%, 11/14), chorioamnionitis (77.8%, 7/9), gastrointestinal symptoms (37.5%, 6/16) and fetal movement decrease (31.3%, 5/16). Listeria monocytogenes were isolated from blood (6 cases), uterus swab (6 cases), blood plus uterus swab (1 case), and neonates (3 cases). All maternal cases recovered well after the termination of pregnancy, even none of them had received empiric antibiotics sensitive to listeria. A very high proportion of adverse pregnancy outcomes occurred (15/16, 93.8%). There were 8 fetal losses. Seven neonates were complicated with listeria sepsis and treated successfully.

CONCLUSIONS

The patients with maternal listeriosis commonly presented with acute fever and an extremely high incidence of adverse pregnancy outcomes, however empiric antibiotics can hardly cover this pathogenic bacterium. So both pregnant women and clinicians should maintain a high level of vigilance against listeriosis and pay more attention to dietetic hygiene.

[The issue of certain infectious diseases of pregnant women in everyday practice Part I. Bacterial and parasitic infections]

AIM OF STUDY

Authors in their text are bringing the latest published findings on the impact of some of the most common infectious diseases on the course and outcome of pregnancies.

TYPE OF STUDY

Review.

RESULTS

Proposals and recommendations for examination, treatment, and management of infected pregnant womans, especially from the view of a primary contact gynecologist.

Epstein Barr virus-induced 3 (EBI3) together with IL-12 negatively regulates T helper 17-mediated immunity to Listeria monocytogenes infection

Although the protective functions by T helper 17 (Th17) cytokines against extracellular bacterial and fungal infection have been well documented, their importance against intracellular bacterial infection remains unclear. Here, we investigated the contribution of Th17 responses to host defense against intracellular bacteria Listeria monocytogenes and found that Th17 cell generation was suppressed in this model. Unexpectedly, mice lacking both p35 and EBI3 cleared L. monocytogenes as efficiently as wild-type mice, whereas p35-deficient mice failed to do so. Furthermore, both innate cells and pathogen-specific T cells from double-deficient mice produced significantly higher IL-17 and IL-22 compared to wild-type mice. The bacterial burden in the liver of double-deficient mice treated with anti-IL-17 was significantly increased compared to those receiving a control Ab. Transfer of Th17 cells specific for listeriolysin O as well as administration of IL-17 and IL-22 significantly suppressed bacterial growth in p35-deficient mice, indicating the critical contribution of Th17 responses to host defense against the intracellular pathogen in the absence of IL-12 and proper Th1 responses. Our findings unveil a novel immune evasion mechanism whereby the intracellular bacteria exploit IL-27EBI3 to suppress Th17-mediated protective immunity.

[Brainstem encephalitis and myelitis due to Listeria monocytogenes: a case report and literature review]

Brainstem encephalitis caused by Listeria monocytogenes is an uncommon form of central nervous system listeriosis; however, it is the most common presentation in immunocompetent individuals. Here, we describe an even more rare combination of rhombencephalitis with severe myelitis caused by L. monocytogenes in an immunocompetent patient. We report the case of a 21-year-old immunocompetent patient who consumed unpasteurized dairy products and experienced headache and vomiting that progressed to an impaired general condition, altered consciousness and ultimately death. The patient had presented to the Neurological Institute of Colombia (INDEC in Spanish) for consultation and was diagnosed with brainstem encephalitis and myelitis caused by Listeria monocytogenes . The differences between this particular case and those reported in the literature will be discussed. It is advisable to initiate antibiotic treatment for Listeria monocytogenes if a patient shows signs of brainstem compromise of possible infectious origin and quickly intensify treatment if there is no or minimal response. It is also necessary to extend radiological assessment to include the spinal column to rule out spinal cord involvement.

Severe invasive listeriosis--case report

Listeriosis is a rare food borne infection which, in the invasive form, presents as bloodstream infection, central nervous system infection, materno-fetal infection, or focal infection. Certain immunosuppressive conditions have been identified as risk factors for severe invasive disease. The invasive forms of listeriosis are associated with a high case fatality rate. We present the case of a 62-year-old male with an unremarkable medical history admitted to the Iasi Infectious Diseases Hospital for fever. headache, ataxia, and diplopia. Physical examination revealed high temperature, confusion, relative bradycardia, and signs of meningeal irritation. Laboratory test showed leukocyt osis with neutrophilia. pathological CSF findings (high WBC count with predominance of neutrophils, low glucose and high protein levels), increased liver enzymes (ALAT, ASAT, AP, gammaGT), and important renal impairment (normal levels at presentation). No abnormalities at chest x-ray, cranial CT and abdominal ultrasound. CSF and blood cultures were positive for Listeria monocytogenes. Under antibiotics (ampicillin and ciprofloxacin), the course was marked by respiratory failure requiring mechanical ventilation, coma, hypotension, tachycardia. and death 12 days after admission. The particularity of this case consists in the association of the two classical forms of invasive listeriosis, meningitis and bacteriemia, with a focal infection. acute hepatitis, and a course marked by multiple organ dysfunction syndromes and exitus in a previously apparently healthy individual.

The roles of IL-12 and IL-23 in CD8+ T cell-mediated immunity against Listeria monocytogenes: Insights from a DC vaccination model

Listeria monocytogenes infection induces a strong inflammatory response characterized by the production of IL-12 and IFN-gamma and protective immunity against this pathogen is dependent on CD8+ T cells (CTL). Recent studies have suggested that these inflammatory cytokines affect the rate of memory CD8+ T cell generation as well as the number of short-lived effector cells generated. The role of the closely related cytokine, IL-23, in this response has not been examined. We hypothesized that IL-12 and IL-23 produced by dendritic cells collectively enhance the generation and function of memory cells. To test this hypothesis, we employed a DC vaccination approach. Mice lacking IL-12 and IL-23 were vaccinated with wild-type (WT), IL-12(-/-), or IL-12/23(-/-) DC and protection to Lm was monitored. Mice vaccinated with WT and IL-12(-/-) DC were resistant to lethal challenge with Lm. Surprisingly, mice vaccinated with IL-12/23(-/-) DC exhibited significantly reduced protection when challenged. Protection correlated with the relative size of the memory pools generated. In summary, these data indicate that IL-23 can partially compensate for the lack of IL-12 in the generation protective immunity against Lm.

Listeriosis in pregnancy: A case report

Listeria monocytogenes is an alimentary infection which can be extremely dangerous for pregnant women. A 34-year-old pregnant woman was hospitalized with fetal cardiac rate alterations and influenza-like symptoms. A caesarean section due to fetal distress was performed. A maternal-fetal listeriosis diagnosis was possible only after the birth through bacteriological and histological examination on both the placenta and the newborn.

High initial frequency of TCR-transgenic CD8 T cells alters inflammation and pathogen clearance without affecting memory T cell function

In adoptive transfer experiments, the initial frequency of naïve TCR-transgenic T cells impacts CD8 T cell phenotype after acute infections. The exact reasons for the observed changes, however, are unclear and it is unknown whether alterations in phenotype translate into impaired memory T cell function as well. Here we perform in vivo comparisons of effector and memory CD8 T cells generated from high or low numbers of naïve precursors. We show that high numbers of adoptively transferred T cells exhibit effector functions that alter systemic inflammation and pathogen abundance in the initial days after infection. While these altered environmental conditions resulted in profound changes in primary effector and memory CD8 T cell phenotype, memory T cells derived from both high and low numbers of naïve precursors protected equally well against re-infection and generated secondary effector and memory T cells that were similar in numbers and phenotype. Our results confirm the necessity to use low numbers of naïve precursors to mimic endogenous immune responses but show at the same time that memory CD8 T cell function in adoptive transfers is independent of input numbers.

[Listeria monocytogenes infection in pregnancy: experience of Pontificia Universidad Católica de Chile University Hospital]

Listeria monocytogenes is Gram-positive facultative intracellular pathogen often foodborne and found elsewhere. It is an uncommon cause of illness in the general population. However, it is an important cause of severe infection in neonates, pregnant women, elderly and immunosuppressed patients. Listeriosis has unique preference for pregnant women. Maternal listeriosis is a diagnostic challenge, and intrauterine infection can lead to severe complications such as amnionitis, preterm labor, spontaneous abortion, stillbirth and neonatal sepsis. From 2001 to 2005, 16 patients with L. monocytogenes were identified in this hospital; four (25%) were pregnant women. Clinical and laboratory findings are described. There were 3 preterm deliveries and 1 spontaneous second trimester abortion. Three women with listeriosis had no predisposing factors other than pregnancy. One patient was on immunosupressive drugs for ulcerative colitis. Fever was the most common symptom. Infected neonates were most commonly diagnosed with early-onset listeriosis (two cases) or fetal demise (one case). Pregnancy can be the only risk factor for listeriosis. Listeriosis should be considered during the evaluation of febrile syndrome in pregnancy as this condition can be the only risk factor. Blood and amniotic fluid cultures are useful diagnostic tests. Perinatal complications remains high.

[Listeriosis a review of current knowledge]

The study includes a recent review of the epidemiology, pathogenesis and clinical picture of listeriosis and new data concerning its treatment.

Orally administeredLactobacillus plantarumreduces pro-inflammatory interleukin secretion in sera fromListeria monocytogenesinfected mice

Lactic acid bacteria have traditionally been thought to have immunomodulating effects. To verify this property,Lactobacillus plantarumwas orally administered to mice (5 × 107colony forming units (c.f.u.)), prior to infection withListeria monocytogenesin order to evaluate the host resistance against an infectious micro-organism and to better define the influence ofL. plantarumon such responses. Balb/c mice were treated daily withL. plantarumor received PBS (sham-treated mice as controls) for 4 weeks. Subsequently, mice were intravenously infected with a clinical isolate ofL. monocytogenes. Our study revealed that the administration ofL. plantarumdid not significantly increase the survival (P = 0·13) of mice (fifteen in each group) afterL. monocytogenesinfection (106 c.f.u./ml), whereas a sub-lethal dose ofL. monocytogenes(105 c.f.u./ml) was eliminated from liver and spleen 5 d after the challenge in bothL. plantarum- and sham-treated mice (n5). Nevertheless, the levels of IL-1β and IL-6 from sera of orally administeredL. plantarumwere drastically reduced at 0, 4 (P < 0·01) and 6 d afterL. monocytogenesinfection, whereas TNF-α production was unaltered. In conclusion, administration ofL. plantarumreduced pro-inflammatory IL production after challenge withL. monocytogenes, although it did not significantly impact the survival of mice. We speculate thatL. plantarumcould exert anti-inflammatory effects, which may represent an important model to reduce inflammatory disorders. Therefore, further studies in human subjects should determine the role ofL. plantarumas an immunomodulatory micro-organism and its relationship in the host protection to pathogens.

Clinical features of liver involvement in adult patients with listeriosis. Review of the literature

Clinical features of liver involvement due to Listeria monocytogenes infection in adults are rarely reported in literature. This is surprising, regarding the current opinion that the portal system is extensively involved in the first stages of pathogenesis in invasive L. monocytogenes disease. A literature search in the PubMed and Embase database revealed 34 cases with clinical features of hepatic involvement due to listeriosis. We systematically analyzed all case reports with respect to clinical manifestations, treatment and outcome. In addition, we added clinical information on a patient diagnosed with a solitary liver abscess due to L. monocytogenes, who was seen at our institution. This review describes the different presentations of liver-involvement reported in listeriosis; solitary liver abscess, multiple liver abscesses and diffuse or granulomatous hepatitis. Distinction between these different forms of liver involvement is clinically relevant as they have a different outcome. We delve into the different pathogenic events leading to different forms of liver involvement. In addition, diagnostic modalities and possible treatments are reviewed.

Inhibition of the RAGE products increases survival in experimental models of severe sepsis and systemic infection

INTRODUCTION

The receptor for advanced glycation end products (RAGE), a multi-ligand member of the immunoglobulin superfamily, contributes to acute and chronic disease processes, including sepsis.

METHODS

We studied the possible therapeutic role of RAGE inhibition in the cecal ligation and puncture (CLP) model of polymicrobial sepsis and a model of systemic listeriosis using mice genetically deficient in RAGE expression or mice injected with a rat anti-murine RAGE monoclonal antibody.

RESULTS

The 7-day survival rates after CLP were 80% for RAGE-/- mice (n = 15) (P < 0.01 versus wild-type), 69% for RAGE+/- mice (n = 23), and 37% for wild-type mice (n = 27). Survival benefits were evident in BALB/c mice given anti-RAGE antibody (n = 15 per group) over serum-treated control animals (P < 0.05). Moreover, delayed treatment with anti-RAGE antibody up to 24 hours after CLP resulted in a significant survival benefit compared with control mice. There was no significant increase in tissue colony counts from enteric Gram-negative or Gram-positive bacteria in animals treated with anti-RAGE antibody. RAGE-/-, RAGE+/-, and anti-RAGE antibody-treated animals were resistant to lethality from Listeria monocytogenes by almost two orders of magnitude compared with wild-type mice.

CONCLUSION

Further studies are warranted to determine the clinical utility of anti-RAGE antibody as a novel treatment for sepsis.

Listeria pleuritis 1 week after lung transplantation

Listeria monocytogenes is an important bacterial pathogen in immunocompromised patients, the elderly, pregnant women and transplant patients, but until now it has not been reported in lung transplants. We report the first case of listeriosis in a lung transplant recipient who presented with a pleural effusion 8 days after transplantation. After the introduction of a thorax drain and the administration of intravenous antibiotics during 3 weeks, the patient recovered completely. This case highlights the increased risk for uncommon respiratory infections in lung transplant patients and examines the specific management of listeria pleuritis.

Artritis séptica por Listeria monocytogenes sobre rodilla protésica en una paciente con artritis reumatoide y macroglobulinemia de Waldenström

Listeria are gram-positive bacilli that can be isolated from soil and in the normal fecal flora of many mammals. It is a uncommon pathogen in the general population, but immunocompromised individuals can develop several focal infections, most notably meningoencephalitis and sepsis. Nevertheless, infectious arthritis caused by Listeria monocytogenes is a exceptional event. We report a new case of prosthetic knee arthritis due to Listeria in a woman with seropositive rheumatoid arthritis and Waldenström s macroglobulinemia receiving prednisone and methotrexate. In addition, we review the literature on listeria joint infections.

Gliotoxin-mediated suppression of innate and adaptive immune functions directed againstListeria monocytogenes

Gliotoxin is an immunosuppressive apoptogenic mycotoxin produced by a number of fungi including important human pathogens as Aspergillus fumigatus. In order to elucidate the potential role of gliotoxin as immunoevasive fungal virulence factor we studied the effects of gliotoxin on the innate and adaptive T cell-mediated immune response against the facultatively intracellular bacterium Listeria monocytogenes. Gliotoxin induced apoptosis of bone marrow-derived macrophages, dendritic cells and CD8 T cells in a dose- and cell type-dependent manner. In vitro the apoptogenic effect of gliotoxin correlated with a strong reduction of TNF-alpha and interleukin (IL)-12 production by dendritic cells and bone marrow-derived macrophages infected with L. monocytogenes and in the case of infected macrophages also in reduced NO-production and recognition by L. monocytogenes-specific CD8 T cells. Further gliotoxin pre-treatment of CD8 T cells reduced target cell lysis. In vivo, treatment of mice with gliotoxin increased the bacterial burden during the innate and the adaptive phase of primary L. monocytogenes infection. Taken together, these results demonstrate the suppressive effects of gliotoxin on the innate and also on the adaptive T cell-mediated antilisterial immunity.

The adjuvant activity of CpG DNA requires T-bet expression in dendritic cells

Treatment with synthetic oligodeoxynucleotides containing CpG motifs (CpG ODNs) is remarkably protective against otherwise lethal infection. Here, we describe an essential role for the transcription factor T-bet in mediating the protective function of CpG ODNs. Loss of T-bet in conventional CD11c(hi) dendritic cells (DCs) and in plasmacytoid DCs impaired production of IFNs. Strikingly, in contrast to Rag2-/- mice, Rag2-/- mice that also lacked T-bet (DKO) could not be rescued from lethal Listeria monocytogenes infection by prior treatment with CpG ODN. Rescue was achieved by adoptive transfer of CD11c(hi) DCs from WT, but not T-bet-/-, CpG ODN-treated donor mice. We conclude that T-bet in DCs is required for the adjuvant activity of CpG ODN in infection, revealing its vital role in innate immunity.

Listeria monocytogenes-induced monomicrobial non-neutrocytic bacterascites

Spontaneous bacterial peritonitis (SBP) is a common complication in patients with cirrhosis of the liver. The organisms most commonly involved in this infection are gram-negative bacteria like Escherichia coli and Klebsiella pneumoniae, and gram-positive bacteria like Streptococcus pneumoniae and Staphylococcus aureus. Listeria monocytogenes is an uncommon gram-positive bacillus implicated in infections in neonates, pregnant females, the elderly, and immunocompromised patients. Listeria monocytogene-induced SBP is rare, with less than 40 cases reported in the medical literature. Monobacterial non-neutrocytic bacterascites (MNB) is a variant of SBP, where the ascitic fluid culture is positive but the ascitic neutrophil count is less than 250/mm3. Forty percent of these patients will subsequently have SBP. Only 2 cases of MNB from L monocytogenes have previously been reported. We report a case of MNB in a patient with cirrhosis whose ascitic neutrophil count was 164/mm', but Gram stain and microbiologic culture showed the growth of L monocytogenes.

Cerebellar abscess due to Listeria monocytogenes

Brain abscess due to listeria monocytogenes mainly involves the cerebral hemispheres. Cerebellar abscess is an infrequent event, which could lead to rapid neurological deterioration if unrecognized. We present a case of multiple brain stem and cerebellar abscesses in a previously healthy individual exposed to unpasteurized milk. This is the 2nd case of cerebellar abscess due to listeria monocytogenes reported in the English literature. The diagnosis of listeria monocytogenes was made in the surgical specimen. Our case illustrates the difficulty of early diagnosis of cerebellar listeria monocytogenes abscesses and the importance of prompt neurosurgical intervention.

Listeriosis: an emerging food-borne disease

Listeriosis is a serious disease acquired by ingestion of foods contaminated with Listeria monocytogenes. Special populations at risk are individuals who are immunocompromised to some extent. The most common clinical findings include meningitis, septicemia, encephalitis, and intrauterine/cervical infections. Food related listeriosis is an unusual occurrence but it is now being thought of as a new, and emergent illness. Numerous types of food products have been implicated in listeriosis infections, but of particular concern are ready to eat products such as lunchmeats, hotdogs, ham/chicken salad, sausages, and roast beef. However, to ensure food safety, there are several methods employed to detect L. monocytogenes in food products and the severity of listeriosis warrants stringent guidelines in food processing facilities. Nevertheless, proper food preparation and handling must be emphasized and individuals who are at an increased risk for the disease must be apprised on how to prevent the occurrence of infection.

Memory phenotype CD8(+) T cells in IL-15 transgenic mice are involved in early protection against a primary infection with Listeria monocytogenes

We recently constructed IL-15 transgenic (Tg) mice using cDNA encoding a secretable isoform of the IL-15 precursor protein under the control of an MHC class I promoter. The IL-15 Tg mice exhibited resistance against a primary infection with Listeria monocytogenes. The numbers of memory CD8(+) T cells were markedly increased in the IL-15 Tg mice following Listeria infection accompanied by sustained IL-15 production. The increased CD44(+)CD8(+) T cells in the infected IL-15 Tg mice were not specialized to recognize Listeria-specific antigen but produced a large amount of IFN-gamma in response to bystander stimulation exogenous IL-15 in combination with IL-12. Furthermore, Listeria-specific Th1 response by CD4(+) T cells was significantly augmented in the IL-15 Tg mice compared with control mice following Listeria infection. In vivo depletion of the CD8(+) T cells by anti-CD8 monoclonal antibody and adoptive transfer of the T cells from naive IL-15 Tg mice indicated that the CD8(+) T cells functioned not only to eliminate bacteria at the early stage of infection but also to promote Th1 response to L. monocytogenes. Overexpression of IL-15 shed light on a novel role of memory CD8(+) T cells in early protection and promotion of Th1 response against a primary infection with L. monocytogenes.

Listeria monocytogenes causing solitary liver abscess. Case report and review of the literature

The authors report on a case of a solitary liver abscess due to Listeria monocytogenes in a 53-year-old diabetic white male and review all published cases of solitary listerial abscesses of the liver. L. monocytogenes is a rare cause of solitary liver abscess which occurs in elderly patients with diabetes mellitus. The clinical signs are variable and often mimic malignancy, with epigastric pain, night sweats and weight loss. Prevalent features are poor control of glycemia, temperature up to 38.5 degrees C and elevated alkaline phosphatase. Optimal treatment includes percutaneous drainage of the hepatic abscess and antibiotic therapy with an aminopenicillin or trimethoprim/sulfamethoxazole. Outcome of the reviewed patients was favourable with no mortality and no relapse of the disease.

Quantitative risk assessment for Listeria monocytogenes in smoked or gravad salmon and rainbow trout in Sweden

The objective of the present work was to develop a quantitative risk assessment model in which the exposure and risk of acquiring listeriosis from consumption of packaged smoked or gravad salmon and rainbow trout were estimated. An Excel spreadsheet model was constructed in which variables were represented by distributions based on surveys of L. monocytogenes in these food products, and on demographic and consumption data. Growth or inactivation was not included in the model. The model was run through Monte Carlo simulations using the @Risk software (Palisade Corporation). The probability of illness per serving was calculated using two dose-response models from the literature. The first was an exponential model in which the species specific constant R, that helps define the dose-response curve, previously has been estimated to be 1.18 x 10(-10) based on German data (GR). In this study, R was estimated to 5.6 x 10(-10) based on Swedish data. The second model was a flexible Weibull-Gamma model (WG), with different coefficients for high- and low-risk groups. The exponential model (GR), although conservative and generally overestimating the risk, still predicted a lower probability of illness than the WG-model. The estimated mean risk per serving was 2.8 x 10(-5) (GR, high-risk group), 2.0 x 10(-3) (WG, low-risk group) and 0.016 (WG, high-risk group), respectively. The average number of reported listeriosis cases in Sweden is 37 per year. In comparison, the mean number of annual cases predicted by the risk assessment model was 168 (range 47 to 2800, GR, high-risk group), and 95 000 (range 34 000 to 1.6 x 10(6), WG high-risk group), respectively. If 1 to 10% (uniform distribution) of strains, instead of all, were considered virulent, the mean number of predicted cases would decrease to nine (GR) and 5200 (WG), respectively. The mean annual cumulative individual risk in the high-risk group based on a monthly exposure was estimated to be 4.0 x 10(-4) (range 8.0 x 10(-8) to 5.4 x 10(-3), GR). This risk increased to 1.5 x 10(-3) (range 1.7 x 10(-5) to 9.2 x 10(-3), GR) based on a weekly exposure. The risk assessment model was most sensitive to the input distribution describing the level of contamination and to a lesser degree on the prevalence of L. monocytogenes, the proportion of virulent strains, and serving sizes. A lack of data on the prevalence and concentration of L. monocytogenes in these products, dose-response data and quantitative information on the proportion of virulent strains were identified.

Unusual food-borne pathogens. Listeria monocytogenes, Aeromonas, Plesiomonas, and Edwardsiella species

Although these four groups of organisms are perceived as infrequent food-borne pathogens or of dubious significance, increasing epidemiologic data indicate that L. monocytogenes is an emerging cause of infections, particularly gastroenteritis. Furthermore, if data are ever generated that prove that most fecal isolates of Aeromonas are involved in bacterial diarrhea, then aeromonads will become recognized as important food-borne pathogens. For Plesiomonas and Edwardsiella, recognition of possible involvement in food-borne disease requires detailed medical histories, including foreign travel, contact with pets or animals, and food consumption histories.

[Bacterial zoonoses: listeria infection of the mother in the 3rd trimester of pregnancy]

Listeria species are Gram-positive bacilli, present in food and in the environment (soil, water). Most of them are fortunately low-virulent, so there is no risk for healthy people. However, in special circumstances, they can be pathogenic, in immunocompromised individuals. Septicaemia in pregnancy is not dangerous for women, but for the foetus, so delayed diagnosis will lead to spontaneous abortion, intrauterine death or eventually to premature labour. We report in our paper case of Listeria septicaemia in a pregnant woman in the third trimester of the pregnancy. Thanks to early diagnosis and subsequent causal antibiotic treatment, we were able to prevent the development of congenital infection and a healthy baby was born.

Cutting edge: anti-CD1 monoclonal antibody treatment reverses the production patterns of TGF-beta 2 and Th1 cytokines and ameliorates listeriosis in mice

Protection against intracellular bacteria by T cells is regulated by Ag-presenting molecules, which comprise classical MHC class I molecules, MHC class II molecules, and nonclassical MHC class Ib molecules. The role of CD1 molecules, which are structurally similar to classical MHC class I gene products, but less polymorphic, is not understood so far. We show that CD1 surface expression increased on APC in Listeria-infected mice. The in vivo treatment with anti-CD1 mAb reduced TGF-beta 2 levels and concomitantly increased secretion of the proinflammatory cytokine TNF, the Th1 cell promoting cytokine IL-12, and the Th1 cell cytokine IFN-gamma at the onset of listerial infection. These findings point to a regulatory role of CD1-reactive cells in the immune response against listeriosis.

Listeriosis: recognizing it, treating it, preventing it

Listeria monocytogenes has become a major pathogen in foodborne illness. It most often affects patients who are pregnant, at the extremes of life, or immunocompromised in some way. A variety of clinical manifestations are possible, but bacteremia and meningitis are most common. This article reviews the epidemiology, microbiology, populations at risk, clinical manifestations, treatment, and prevention of listeriosis.

Central nervous system infection with Listeria monocytogenes. 33 years' experience at a general hospital and review of 776 episodes from the literature

We reviewed 776 previously reported and 44 new cases of CNS listeriosis outside of pregnancy and the neonatal period, and evaluated the epidemiologic, diagnostic, and therapeutic characteristics of this infection. Among patients with Listeria meningitis/meningoencephalitis, hematologic malignancy and kidney transplantation were the leading predisposing factors, but 36% of patients had no underlying diseases recognized. The infection occurred throughout life, with a higher incidence before the age of 3 and after the age of 45-50 years. Fever, altered sensorium, and headache were the most common symptoms, but 42% of patients had no meningeal signs on admission. Compared with patients with acute meningitis due to other bacterial pathogens, patients with Listeria infection had a significantly lower incidence of meningeal signs, and the CSF profile was significantly less likely to have a high WBC count or a high protein concentration. Gram stain of CSF was negative in two-thirds of cases of CNS listeriosis. One-third of patients had focal neurologic findings, and approximately one-fourth developed seizures over their course. Mortality was 26% overall, and was higher among patients with seizures and those older than 65 years of age. Relapse occurred in 7% of episodes. Ampicillin for a minimum of 15-21 days (with an aminoglycoside for at least the first 7-10 days) remains the treatment of choice. Cerebritis/abscess due to L. monocytogenes, without meningeal involvement, is less common but may be diagnosed by blood cultures and CNS imaging, or by stereotactic biopsy. Longer antibiotic therapy (at least 5-6 weeks) is needed in the presence of localized CNS involvement.

The effect of interleukin-10 on meningeal inflammation in experimental bacterial meningitis

Interleukin-10 (IL-10) is a cytokine with antiinflammatory effects. In a rabbit model of meningitis, IL-10 was given intracisternally or intravenously to evaluate the impact on inflammation induced by lipooligosaccharide (LOS), Haemophilus influenzae type b (Hib), or Listeria monocytogenes. Intracisternal IL-10 in concentrations >1 microg significantly reduced tumor necrosis factor-alpha (TNF-alpha) and lactate values in cerebrospinal fluid (CSF). Intravenous IL-10 (1 mg/kg) in two doses after intracisternal LOS significantly reduced CSF TNF-alpha and lactate. When Hib was used, animals were treated with ceftriaxone and dexamethasone with or without IL-10 (1 mg/kg). TNF-alpha was significantly reduced in animals treated with IL-10, dexamethasone, or both compared with levels in rabbits receiving ceftriaxone alone. Comparable results were obtained when L. monocytogenes was inoculated and animals were treated with ampicillin with or without IL-10, dexamethasone, or nothing. In conclusion, IL-10 modulates CSF TNF-alpha concentrations in experimental LOS, Hib, or L. monocytogenes meningitis. The maximal inhibitory effect was seen when IL-10 and dexamethasone were combined.

[Cerebral listeriosis in cattle: literature review and retrospective analysis of individual cases]

Between 1990 and 1994, 89 cattle with signs of affection of the central nervous system were referred to the Clinic for Food Animals and Horses, University of Bern; in 17 cases of which, cerebral listeriosis was diagnosed. History, clinical, hematologic findings and cerebrospinal fluid analysis at admission were evaluated retrospectively. Four cattle were slaughtered after cerebral listeriosis had been diagnosed clinically because of economic reasons. Therapy, consisting of administration of penicillin (i.m./i.v.), intravenous fluids (including bicarbonate replacement), and oral fluids and rumen juice was initiated in the remaining 13 cases. Five of the 13 cattle were refractory to treatment and had to be euthanatized, one to two days after initiation of therapy. Clinical diagnosis of cerebral listeriosis was confirmed by histological examination of brain stem tissue in all nine cattle that were slaughtered or euthanatized; however, Listeria monocytogenes was isolated by standard culturing of brain stem tissue in two of these cases only. Eight to 62 months after discharge from the clinic, telephone interview with the owners of the surviving animals revealed that recovery had been uneventful and satisfactory in all of the eight cases.

IL-4 neutralization or TNF-alpha treatment ameliorate disease by an intracellular pathogen in IFN-gamma receptor-deficient mice

Successful control of infectious disease depends on aquisition of an appropriate protective immune response. IFN-gamma, first produced by NK cells and then by Th1 cells, is central to acquired resistance against intracellular bacteria, including Listeria monocytogenes. In contrast, IL-4 is not generated to a measurable degree. Here we show that IL-4 is produced during listeriosis by IFN-gamma receptor gene disruption (IFN-gammaR(-/-)) mutant mice. Production of TNF was diminished, whereas IL-12 production was virtually unchanged in these mutants. Neutralization of IL-4 with anti-IL-4 mAb, as well as TNF-alpha reconstitution with rTNF-alpha, ameliorated listeriosis. These findings demonstrate the detrimental effects of IL-4 in listeriosis independent of IFN-gamma down-regulation and document the far-reaching consequences of a single cytokine deficiency on other cytokines. In cases where the primary gene defect cannot be restored, precise identification of secondary effects will promote rational immunotherapy based on neutralization or reconstitution of secondary immune deviations.

[MRI and Listeria monocytogenes rhombencephalitis]

Rhombencephalitidis is a serious form of brainstem inflammation, difficult to diagnose on the basis of clinical and laboratory findings alone. We describe the MR appearance of 3 cases of Listeria monocytogenes rhombencephalitidis and correlate the findings with clinical information. MR imaging is crucial for early diagnosis of this illness: patchy signal hyperintensity throughout the medulla and cerebellar peduncles on T2 weighted images, always in association with a hypointense dot; numerous gadolinium-enhanced microabcesses in the rhombencephalon. MR imaging is very useful for follow-up examinations.

In vivo cytokine production in murine listeriosis. Evidence for immunoregulation by gamma delta+ T cells

Differential cytokine production by gamma delta+ T cells influences Th1 and Th2 responses. Here, we describe the in vivo kinetics of peritoneal and splenic gamma delta+, CD4+, and CD8+ T cell cytokine responses during primary and secondary Listeria infections. The data show differences in the kinetics of IFN-gamma-producing alpha beta+ splenocytes consistent with immunologic memory. Most noteworthy, however, was the elevated production of IL-10 by splenic gamma delta+ T cells in the red pulp and marginal zones that coincided with maximal IFN-gamma production and with a decrease in inflammation and tissue damage. This result implies a role for gamma delta+ T cells in the control of Th1 responses.

Joint infections due to Listeria monocytogenes: case report and review

Joint infections of bone are unusual manifestations of listerial infection. Fourteen cases of septic arthritis due to Listeria monocytogenes have been previously described in adults. We report the 15th case of septic arthritis due to Listeria in which bilateral prosthetic hips in a renal transplant patient were involved. In addition, we review the literature on listerial joint infections.

Enteral formula composition does not affect response to lethal infectious challenge in mice

The effects of enteral formulations on the response of mice to infectious challenge with Listeria monocytogenes, influenza A or Candida albicans were studied to test the efficacy of specialized ingredients. CF-1 outbred female mice (12-15 g) were fed nonpurified diet (Purina No. 5002) or commercially available liquid formulas: Osmolite HN, Perative or Impact. There were no differences between the groups fed the liquid formulas with regards to mean survival time or percentage of survivors in any of these models of infection. Examination of spleens from the groups challenged with L. monocytogenes, lungs from mice infected with Influenza A and kidneys from the groups challenged with C. albicans revealed no differences in cure rate of survivors. Pre-feeding periods of up to 8 d before infection produced similar results for mice fed enteral formulations compared to nonpurified diet. Contrary to previous reports, the use of Impact did not improve resistance to disease in mice challenged with lethal doses of L. monocytogenes, as compared with mice fed Osmolite HN. Additionally, mice fed Impact, Perative, or nonpurified diet responded similarly to challenge with L. monocytogenes, C. albicans or influenza A. The results indicate that these acute lethal animal models of infectious challenge may be of limited use to distinguish effects of modified nutrient composition of enteral formulas.

Recombinant interleukin-12 enhances resistance of mice to Listeria monocytogenes infection

The effect of recombinant murine IL-12 (rIL-12) or anti-IL-12 antibody administration on resistance to murine listeriosis was investigated. Mice given a single 0.5 micrograms dose of rIL-12 had 1.5 log10 fewer listeriae in their spleens and livers as compared with control infected mice 3 days after L. monocytogenes challenge. Conversely, administration of anti-IL-12 IgG caused an equivalent increase in the cfu of L. monocytogenes recovered from the spleens and livers as compared to control mice. This is the first report of such a protective effect from a single dose of rIL-12. Treatment of uninfected mice with rIL-12 induced IFN-gamma mRNA production in their livers. Infection of mice with L. monocytogenes caused a similar increase in IFN-gamma mRNA levels that was not increased further by concurrent treatment with rIL-12. Treatment of mice with an anti-IFN-gamma MAb eliminated the protective effect of IL-12 on Listeria infection. Expression of TNF-alpha, IL-10 and IL-12p40 mRNA in L. monocytogenes-infected mice were not significantly altered by administration of either anti-IL-12 IgG or rIL-12. rIL-12 administration was associated with increased serum AST levels, a measure of liver damage, 1 day after treatment in L. monocytogenes-infected mice. In addition, rIL-12 administration was associated with the increased presence of small inflammatory foci and necrotic hepatocytes in both infected and uninfected mice, suggesting a proinflammatory role for IL-12 in the liver.

Listeria monocytogenes and severe newborn respiratory failure supported with extracorporeal membrane oxygenation

OBJECTIVE

To determine the efficacy of extracorporeal membrane oxygenation (ECMO) in newborn infants with early-onset Listeria monocytogenes infection, necrotizing pneumonia, and severe respiratory failure.

DESIGN

Patient series.

SETTING

ECMO referral centers.

PARTICIPANTS

The Extracorporeal Life Support Organization Registry database of patients supported with ECMO between 1975 and 1991.

INTERVENTION

ECMO.

MEASUREMENTS AND RESULTS

Nine neonates were identified who were supported with ECMO for severe respiratory failure associated with L monocytogenes infection. Microbiologic studies demonstrated L monocytogenes organisms in the blood of all infants, and pneumonia was diagnosed by roentgenogram and/or isolation of L monocytogenes organisms in tracheobronchial secretions. All infants experienced progressive respiratory deterioration by age 36 hours and were placed on venoarterial bypass by 96 hours, having met institution-based criteria predictive of 80% to 90% mortality. The duration of ECMO for patients with Listeria infection (median, 210 hours; range, 137 to 454 hours) was prolonged compared with the duration of ECMO for neonates in all other registry diagnostic categories (median, 114 hours; range, 1 to 744 hours; N = 5146, P = .035). Six of the nine infants recovered completely.

CONCLUSIONS

These data suggest that ECMO is efficacious in patients with severe respiratory failure secondary to Listeria sepsis. Prolonged time on bypass should be expected when Listeria sepsis is associated with severe necrotizing pneumonia.

In vivo augmentation of IFN-gamma with a rIL-12 human/mouse chimera: pleiotropic effects against infectious agents in mice and rats

A heterodimer containing the mouse 35 kDa and human 40 kDa subunit of IL-12 was expressed in COS cells (cIL-12). Administration of 25-200 U of the cIL-12-COS supernatant to mice twice daily for 2 days augmented spleen cell IFN-gamma production in response to IL-2 and peritoneal macrophage activity (superoxide and nitrites) as compared to animals receiving mock transfected supernatants. cIL-12 also increased levels of IFN-gamma in serum but most dramatically following an LPS injection (50-fold over controls). Animals pretreated with cIL-12 suffered enhanced mortality following challenge with the Gram negative organism E. coli but enhanced survival or clearance following infection with the Gram positive organisms L. monocytogenes and S. aureus. Although daily treatment of mice with cIL-12 following an intranasal influenza A infection elevated levels of IFN-gamma in the bronchioalveolar lavage fluid three-fold over controls, neither prophylactic or therapeutic treatment with the same dose level decreased viral titres in the lung. In addition, no effect was observed in animals infected with encephalomyocarditis virus or respiratory syncytial virus. Therefore, cIL-12 is a potent in vivo augmentor of IFN-gamma production. It has differential effects on infectious disease depending on the invading organism and time of administration; being efficacious for intracellular bacteria but ineffective at the same dose levels against viral diseases.