Listeria infection in women

A review of the literature of Listeria monocytogenes in Africa highlights breast milk as an overlooked human source

According to the latest WHO estimates (2015) of the global burden of foodborne diseases, Listeria monocytogenes is responsible for one of the most serious foodborne infections and commonly results in severe clinical outcomes. The 2013 French MONALISA prospective cohort identified that women born in Africa has a 3-fold increase in the risk of maternal neonatal listeriosis. One of the largest L. monocytogenes outbreaks occurred in South Africa in 2017-2018 with over 1,000 cases. Moreover, recent findings identified L. monocytogenes in human breast milk in Mali and Senegal with its relative abundance positively correlated with severe acute malnutrition. These observations suggest that the carriage of L. monocytogenes in Africa should be further explored, starting with the existing literature. For that purpose, we searched the peer-reviewed and grey literature published dating back to 1926 to date using six databases. Ultimately, 225 articles were included in this review. We highlighted that L. monocytogenes is detected in various sample types including environmental samples, food samples as well as animal and human samples. These studies were mostly conducted in five east African countries, four west African countries, four north African countries, and two Southern African countries. Moreover, only ≈ 0.2% of the Listeria monocytogenes genomes available on NCBI were obtained from African samples, contracted with its detection. The pangenome resulting from the African Listeria monocytogenes samples revealed three clusters including two from South-African strains as well as one consisting of the strains isolated from breast milk in Mali and Senegal and, a vaginal post-miscarriage sample. This suggests there was a clonal complex circulating in Mali and Senegal. As this clone has not been associated to infections, further studies should be conducted to confirm its circulation in the region and explore its association with foodborne infections. Moreover, it is apparent that more resources should be allocated to the detection of L. monocytogenes as only 15/54 countries have reported its detection in the literature. It seems paramount to map the presence and carriage of L. monocytogenes in all African countries to prevent listeriosis outbreaks and the related miscarriages and confirm its association with severe acute malnutrition.

A Whole Genome Sequencing-Based Epidemiological Investigation of a Pregnancy-Related Invasive Listeriosis Case in Central Italy

Listeriosis is currently the fifth most common foodborne disease in Europe. Most cases are sporadic; however, outbreaks have also been reported. Compared to other foodborne infections, listeriosis has a modest incidence but can cause life-threatening complications, especially in elderly or immunocompromised people and pregnant women. In the latter case, the pathology can be the cause of premature birth or spontaneous abortion, especially if the fetus is affected during the first months of gestation. The causative agent of listeriosis, Listeria monocytogenes, is characterized by the innate ability to survive in the environment and in food, even in adverse conditions and for long periods. Ready-to-eat food represents the category most at risk for contracting listeriosis. This study presents the result of an investigation carried out on a case of maternal-fetal transmission of listeriosis which occurred in 2020 in central Italy and which was linked, with a retrospective approach, to other cases residing in the same city of the pregnant woman. Thanks to the use of next-generation sequencing methodologies, it was possible to identify an outbreak of infection, linked to the consumption of ready-to-eat sliced products sold in a supermarket in the investigated city.

A vigilant observation to pregnancy associated listeriosis in Africa: Systematic review and meta-analysis

The burden of human listeriosis, an emerging food-borne illness would be higher in Africa due to poor food processing practices. The severity of the disease and the high case fatality rate make human listeriosis an important public health problem. Besides, pregnant women and their fetuses are at higher risk of gaining human listeriosis. Thus, we planned to estimate the pooled prevalence of pregnancy-associated human listeriosis in Africa. Primary studies were exhaustively searched using PubMed, Cochrane, Web of Science, Google Scholar, and University of Gondar online research repository. Observational studies (cross-sectional) revealing the pregnancy-associated human listeriosis were incorporated. Eligible studies were selected and critically appraised for quality using the Joanna Briggs Institute (JBI) quality appraisal checklist. The required data were extracted and exported to Stata version 14 for meta-analysis. The pooled prevalence of pregnancy-associated human listeriosis in Africa was estimated using a weighted inverse random effect model. Sensitivity and sub-group analysis were conducted for evidence of heterogeneity. Among 639 reviewed articles, 5 articles were eligible with total study participants of 621. The pooled prevalence of pregnancy-associated listeriosis was found to be 5.17% (95% CI, 1.51, 8.82). The pooled level resistance of isolates was high. Cotrimoxazole and erythromycin were the relative choices of antibiotics for pregnancy-associated listeriosis in Africa. The burden of pregnancy-associated listeriosis in Africa was higher with an increased level of antibiotic resistance. Therefore, we recommend due attention to the deadly emerging disease in terms of health educations and the role of food hygiene particularly for risk groups, pregnant women. The antibiotics of choice should be after performing drug susceptibility test.

Characteristics and Outcomes of Neonates With Blood Stream Infection Due to Listeria monocytogenes

BACKGROUND

Infection due to Listeria monocytogenes (LM) is rare in neonates; thus, its clinical presentation and outcomes are not commonly reported, especially in low- and middle-income countries. In 2017, South Africa had an outbreak due to LM.

OBJECTIVE

To determine demographic characteristics, clinical and laboratory findings and outcomes of all neonates infected with LM during the outbreak period.

METHODS

This is a retrospective analytic study. Clinical and laboratory records of neonates admitted at Chris Hani Baragwanath Academic Hospital from January 2017 to May 2018 with positive blood and cerebrospinal fluid culture with LM were reviewed for demographic characteristics, clinical presentation, ancillary laboratory test results and outcomes at hospital discharge.

RESULTS

There were 42 neonates with positive cultures due to LM. Thirty-four (81%) were born preterm. Mode of delivery was vaginal in 78.6% and 31.0% were HIV exposed. All patients presented within the first 6 days of life as an early-onset disease. Common clinical presentation was respiratory depression (52.4%) and respiratory distress (38.1%) with 69% requiring invasive or noninvasive respiratory support. Common abnormal laboratory findings were high C-reactive protein (77.1%) followed by leukopenia (23.8%). Fourteen patients (40%) had features of meningitis based on blood and cerebrospinal fluid findings (4 culture proven). There were 11 deaths at hospital discharge, giving a mortality rate of 26.2%.

CONCLUSIONS

The majority of neonates infected with LM were born preterm, raising the possibility that LM itself may have been responsible for preterm labor. All presented in the first 6 days of life and most presented with respiratory distress or depression. A high proportion had meningitis, and there was a high-mortality overall.

Development of magnetosomes-based biosensor for the detection of Listeria monocytogenes from food sample

Listeriosis through contaminated food is one of the leading causes of premature deaths in pregnant women and new born babies. Here, the authors have developed a magnetosomes-based biosensor for the rapid, sensitive, specific and cost-effective detection of Listeria monocytogenes from food sample. Magnetosomes were extracted from Magnetospirillum sp. RJS1 and then directly bound to anti-Listeriolysin antibody (0.25-1 µg/ml), confirmed in spectroscopy. Listeriolysin (LLO) protein (0.01-7 µg/ml) was optimised in enzyme-linked immunosorbent assay. Magnetosomes was conjugated with LLO antibody (0.25 µg/ml) in optimum concentration to detect LLO protein (0.01 µg/ml). Magnetosomes-LLO antibody complex was 25% cost effective. The magnetosomes-LLO antibody complex was directly stabilised on screen printed electrode using external magnet. The significant increase in resistance (R_CT value) on the electrode surface with increase in concentration of LLO protein was confirmed in impedance spectroscopy. The L. monocytogenes contaminated milk and water sample were processed and extracted LLO protein was detected in the biosensor. The specificity of the biosensor was confirmed in cross-reactivity assay with other food pathogens. The detection limit of 10¹ Cfu/ml in both water and milk sample manifests the sensitive nature of the biosensor. The capture efficiency and field emission scanning electron microscopy confirmed positive interaction of Listeria cells with magnetosomes-antibody complex.

Case report: whole genome sequencing based investigation of maternal-neonatal listeriosis in Sichuan, China

BACKGROUND

Neonatal listeriosis is a rare but severe disease manifesting as septicemia and central nervous system (CNS) infections with a high fatality rate of around 20 to 30%. Whole genome sequencing (WGS) is a promising technique for pathogen identification and infection source tracing with its high resolution.

CASE PRESENTATION

A case of neonatal sepsis with listeriosis was reported with positive blood culture for Listeria monocytogenes. The case was investigated to confirm the vertical transmission of the infection and identify the potential food source of the maternal L. monocytogenes infection using WGS. L. monocytogenes was isolated from the neonate's blood sample the day after caesarean delivery and from the mother's genital and pudenda swab samples 5 days and 13 days after caesarean delivery. WGS showed that the isolate from the neonate was identical to the genome type of the isolates from the mother, with only one of the 4 isolates from the mother differing by one single nucleotide polymorphism (SNP). By WGS, one L. monocytogenes isolate from a ready-to-eat (RTE) meat sample in the patients' community market shared the same sequence type but was ruled out as the cause of infection, with 57 SNP differences to the strain causing the maternal-neonatal infection. The food isolate also carried a novel plasmid pLM1686 that harbored heavy metal resistance genes. After caesarean section, the mother was treated with a third generation cephalosporin which L. monocytogenes is naturally resistant to, which may explain why genital and pudenda swabs were still culture-positive for L. monocytogenes 13 days after delivery.

CONCLUSIONS

Genital swab culture for L. monocytogenes had been informative in the diagnosis of maternal listeriosis in this case. The high resolution of WGS confirmed the maternal-neonatal transmission of L. monocytogenes infection and ruled out the L. monocytogenes contaminated RTE meat from the local market as the direct source of the mother's infection.

Synergistic activities of gaseous oregano and thyme thymol essential oils against Listeria monocytogenes on surfaces of a laboratory medium and radish sprouts

We investigated combinations of gaseous essential oils (EO gases) for their synergistic inhibitory activities against Listeria monocytogenes on a laboratory medium and radish sprouts. The minimum inhibitory concentrations and minimum lethal concentrations of oregano, thyme thymol, and cinnamon bark EO gases against L. monocytogenes were 0.0781 μL/mL on nutrient agar supplemented with glucose and bromocresol purple (NGBA). A checkerboard assay showed that combinations of oregano and thyme thymol EO gases and of oregano and cinnamon bark EO gases exert the strongest synergistic antilisterial activity (fractional inhibitory concentration index [FICI] = 0.3750). A combination of thyme thymol and cinnamon bark EO gases also had a synergistic effect (FICI = 0.5000) on L. monocytogenes on NGBA. Combinations of oregano and thyme thymol EO gases were tested for synergistic antimicrobial activity against L. monocytogenes on radish sprouts. A combination of these gases, each at 0.313 μL/mL, caused a significant (P ≤ 0.05) reduction in the number of L. monocytogenes on radish sprouts compared with reductions caused by treatment with oregano or thyme thymol EO gas alone at the same concentration. Our findings provide information that will be useful when developing antimicrobial applications using EO gases to control L. monocytogenes in the food industry.

Pregnancy-related listeriosis

About one in seven cases of listeriosis occurs in pregnant women, and, although listeriosis is rare, it is the third leading cause of death from food-borne infections. Pregnancy-related listeriosis increases the risk for fetal and neonatal mortality by approximately 21%. During pregnancy, infections are more likely to occur in the third trimester (66%) than the first trimester (3%). However, fetal and neonatal adverse effects are less common as gestational age increases or with older gestational age at birth. Pregnant women seem highly susceptible in some listeriosis outbreaks making up a large percentage of cases, whereas others contain very few. Whether this results from differences in strains of L. monocytogenes, exposures, or other factors remains to be determined. Food and Agriculture Organization of United Nations/World Health Organization (FAO/WHO) estimates the human lethal dose for 50% (LD₅₀ ) for fetal/neonatal loss is 1.9 × 10⁶ colony forming units (CFUs) L. monocytogenes. Animal models have been developed for pregnancy-related listeriosis showing similar susceptibility and clinical outcomes as in humans. Nonhuman primate and guinea pig animal models have similar (LD₅₀ ) values to the estimated human LD₅₀ . Additional animal studies are needed to understand the pathways leading to fetal and neonatal listeriosis in humans. More information is needed to understand dose response, to model risk for listeriosis at lower concentrations, and to determine why some pregnant women may be more susceptible than others. To better treat listeriosis during pregnancy, biomarkers for early diagnosis of listeriosis are also needed. Last, pregnant women need to be educated about avoiding high-risk foods, like Mexican-style cheese and ready-to-eat meats. Birth Defects Research 109:324-335, 2017.© 2017 Wiley Periodicals, Inc.

Pediococcus pentosaceus SB83 as a potential probiotic incorporated in a liquid system for vaginal delivery

Pediococcus pentosaceus SB83 is a bacteriocinogenic culture having potential use as a vaginal probiotic. The objective of this study was to evaluate the behaviour of P. pentosaceus SB83 incorporated in a liquid system for eventually formulating a gel for vaginal delivery. The vaginal probiotic incorporated into glycerol was able to survive in simulated vaginal fluid at normal vaginal pH (4.2) and at pH of vaginal infections (5.5 and 6.5). The probiotic can be stored at 4 °C for a longer period of time than at room temperature, however, after 13 weeks of storage at low temperature, there was a total loss of viable cells. The probiotic strain incorporated into glycerol showed bacteriocinogenic activity in simulated vaginal fluid, although the antimicrobial activity against Listeria monocytogenes declined during storage. This study showed the behaviour of P. pentosaceus SB83 in glycerol and in simulated vaginal fluid. However, it is necessary to optimise the formulation to produce an actively probiotic vaginal gel.

A rapidly fatal sepsis caused by listeria monocytogenes type-4b in a patient with chronic renal failure

INTRODUCTION

Listeria monocytogenes is a significant zoonosis causing invasive infections in the susceptible persons. The current paper presented a patient who died due to a rapidly-progressing multiple organ failure (MOF) as a result of severe sepsis caused by L. monocytogenes.

CASE PRESENTATION

A 70-years-old patient with chronic renal failure was admitted to the infectious diseases clinic due to diarrhea for one day. He was hospitalized and the body fluid samples were collected for laboratory analyses. Within few hours, his vital findings worsened, and he developed respiratory arrest. Ceftriaxone and gentamycin were administrated. However, he died due to disseminated intravascular coagulation, septic shock and meningoencephalitis at the 22nd hour of admission. Causative agent was identified as L. monocytogenes serotype-4b in post-mortem period.

DISCUSSION

L. monocytogenes can cause progressive and rapidly fatal infections in the vulnerable persons, with multisystem involvement. Since this bacterium is not susceptible to cephalosporines, it will be better to consider effective antimicrobials in the treatment of the possible cases.

Listeriosis during Pregnancy: A Public Health Concern

Listeria was first described in 1926 by Murray, Webb, and Swann, who discovered it while investigating an epidemic infection among laboratory rabbits and guinea pigs. The role of Listeria monocytogenes as a foodborne pathogen was definitively recognized during the 1980s. This recognition was the consequence of a number of epidemic human outbreaks due to the consumption of contaminated foods, in Canada, in the USA and in Europe. Listeriosis is especially severe in immunocompromised individuals such as pregnant women. The disease has a low incidence of infection, although this is undeniably increasing, with a high fatality rate amongst those infected. In pregnant women listeriosis may cause abortion, fetal death, or neonatal morbidity in the form of septicemia and meningitis. Improved education concerning the disease, its transmission, and prevention measures for immunocompromised individuals and pregnant women has been identified as a pressing need.

Effects of processing and storage on Pediococcus pentosaceus SB83 in vaginal formulations: lyophilized powder and tablets

Vaginal probiotics have an important role in preventing the colonization of the vagina by pathogens. This study aimed to investigate different formulations with Pediococcus pentosaceus SB83 (lyophilized powder and tablets with and without retarding polymer) in order to verify its stability and antilisterial activity after manufacture and during storage. The bacteriocinogenic activity of P. pentosaceus SB83 against Listeria monocytogenes was evaluated in simulated vaginal fluid. Suspension of Pediococcus pentosaceus SB83 reduced the pathogen only after 2 h and the lyophilized bacteria after 24 h of contact, and, in the tablets, P. pentosaceus SB83 lost the antimicrobial activity. The pH of simulated vaginal fluid decreased for all the tested conditions. As lyophilized powder demonstrated better results concerning antimicrobial activity, this formulation was selected to evaluate the antilisterial activity during the 12 months of storage. During storage at room temperature, lyophilized bacteria totally inhibited the pathogen only until one month of storage. At 4°C, P. pentosaceus SB83 showed antimicrobial activity during all the time of storage investigated. Therefore, the better formulation of P. pentosaceus SB83 is the lyophilized powder stored at 4°C, which may be administered intravaginally as a washing solution.

Evaluation of characteristics of Pediococcus spp. to be used as a vaginal probiotic

AIMS

The aim of our research was to select, identify and characterize an isolate of lactic acid bacteria to be considered as a vaginal probiotic.

METHODS AND RESULTS

Thirty-five isolates of Pediococcus spp. showed bacteriocinogenic activity against Listeria monocytogenes and the ability to survive in simulated vaginal fluid (SVF) at pH 4.2. One isolate of Pediococcus spp. was selected and characterized to evaluate its safety before the use as vaginal probiotic. Pediococcus pentosaceus SB83 did not show the presence of virulence factors such as the production of gelatinase, lipase and DNase, haemolytic activity, nor the presence of virulence genes (genes esp, agg, gelE, efaAfm, efaAfs, cylA, cylB and cylM). Pediococcus pentosaceus SB83 was considered sensitive to chloramphenicol, gentamicin, streptomycin, kanamycin, erythromycin and ampicillin. This strain was considered resistant to tetracycline and vancomycin. Pediococcus pentosaceus SB83 was a biofilm producer at different pH values (4.2, 5.5 and 6.5) in SVF and in de Man, Rogosa and Sharpe medium.

CONCLUSIONS

The in vitro results provide a basis for the use of P. pentosaceus SB83 as a vaginal probiotic, to prevent colonization by L. monocytogenes in pregnant women.

SIGNIFICANCE AND IMPACT OF STUDY

The application of vaginal probiotics could have the potential for preventing vaginal infections and consequently reduce abortion and neonatal infections.

Recent developments in bio-molecular electronics techniques for food pathogens

Food borne illnesses contribute to the majority of infections caused by pathogenic microorganisms. Detection of these pathogens originating from different sources has led to increased interest of researchers. New bio-molecular techniques for food pathogen detection are being developed to improve the sensor characteristics such as sensitivity, reusability, simplicity and economic viability. Present article deals with the various methods of food pathogen detection with special emphasis on bio-molecular electronics techniques such as biosensors, microarrays, electronic nose, and nano-materials based methods.

Listeriosis: clinical presentation

Listeria monocytogenes is an uncommon cause of illness in the general population. However, this bacterium is an important cause of severe infections in neonates, pregnant women, the elderly, transplant recipients and other patients with impaired cell-mediated immunity. Various clinical syndromes due to L. monocytogenes have been described such as sepsis, central nervous system infections, endocarditis, gastroenteritis and localized infections. A review of the clinical presentation of listeriosis is given in this paper.