Sepsis and meningitis due to Listeria monocytogenes

Ribosomally synthesized bacteriocins of lactic acid bacteria: Simplicity yet having wide potentials - A review

Bacteriocins are ribosomally made bacterial peptides that have outstanding contributions in the field of food industry, as biopreservatives, and promising potentials in the medical field for improving human and animal health. Bacteriocins have many advantages over antibiotics such as being primary metabolites with relatively simpler biosynthetic mechanisms, which made their bioengineering for activity or specificity improving purposes much easier. Also, bacteriocins are degraded by proteolytic enzymes and do not stay in environment, which reduce chances of developing resistance. Bacteriocins can improve activity of some antibiotics, and some bacteriocins show potency against multidrug-resistant bacteria. Moreover, some potent bacteriocins have antiviral, antifungal, and antiprotozoal (antileishmanial) activities. On the other hand, bacteriocins have been introduced into the treatment of some ulcers and types of cancer. These potentials make bacteriocins attract extra attention as promising biotechnological tool. Hence, the history, characteristics, and classification of bacteriocins are described in this review. Furthermore, the main difference between bacteriocins and other antimicrobial peptides is clarified. Also, bacteriocins biosynthesis and identified modes of action are elucidated. Additionally, current and potential applications of bacteriocins in food and medical fields are highlighted. Finally, future perspectives concerning studying bacteriocins and their applications are discussed.

Human Listeriosis

Listeria monocytogenes is a Gram-positive facultative intracellular pathogen that can cause severe invasive infections upon ingestion with contaminated food. Clinically, listerial disease, or listeriosis, most often presents as bacteremia, meningitis or meningoencephalitis, and pregnancy-associated infections manifesting as miscarriage or neonatal sepsis. Invasive listeriosis is life-threatening and a main cause of foodborne illness leading to hospital admissions in Western countries. Sources of contamination can be identified through international surveillance systems for foodborne bacteria and strains' genetic data sharing. Large-scale whole genome studies have increased our knowledge on the diversity and evolution of L. monocytogenes, while recent pathophysiological investigations have improved our mechanistic understanding of listeriosis. In this article, we present an overview of human listeriosis with particular focus on relevant features of the causative bacterium, epidemiology, risk groups, pathogenesis, clinical manifestations, and treatment and prevention.

Virulent endocarditis due to Haemophilus parainfluenzae: A systematic review of the literature

BACKGROUND

Haemophilus parainfluenzae (HPI) belongs to the HACEK (Haemophilus spp., Aggregatibacter spp., Cardiobacterium spp., Eikenella spp., and Kingella spp.) group of organisms. The HACEK group of organisms are a part of the oropharyngeal flora and can cause invasive opportunistic infection such infective endocarditis (IE) in hosts with compromised immunological barriers.

AIM

To perform a 20-year systematic review of the literature characterizing the clinical presentation, epidemiology and prognosis of HPI IE.

METHODS

We performed a systematic review of Medline, Pubmed, Scopus and Embase from 2000 to 2022 to identify all cases of HPI IE.

RESULTS

Thirty-nine adult cases were identified. HPI IE was found to affect males slightly more than females and is common in patients with predisposing risk factors such as underlying valvular abnormalities. It mostly affected the mitral valve and had an indolent course; significantly sized vegetations (> 1 cm) developed in most cases. Central nervous system septic embolization was common. It had a favorable prognosis compared to staphylococcal and streptococcal IE.

CONCLUSION

Clinicians should be attentive to the indolent course of HPI IE and the presence of predisposing risk factors in order to allow for timely management.

Endothelial Dysfunction and Impaired Neurovascular Coupling Responses Precede Cognitive Impairment in a Mouse Model of Geriatric Sepsis

Sepsis is a life-threatening condition, the incidence of which is significantly increased in elderly patients. One of the long-lasting effects of sepsis is cognitive impairment defined as a new deficit or exacerbation of preexisting deficits in global cognition or executive function. Normal brain function is dependent on moment-to-moment adjustment of cerebral blood flow to match the increased demands of active brain regions. This homeostatic mechanism, termed neurovascular coupling (NVC, also known as functional hyperemia), is critically dependent on the production of vasodilator NO by microvascular endothelial cells in response to mediators released from activated astrocytes. The goal of this study was to test the hypothesis that sepsis in aging leads to impairment of NVC responses early after treatment and that this neurovascular dysfunction associates with impairments in cognitive performance and vascular endothelial dysfunction. To test this hypothesis, we used a commonly studied bacterial pathogen, Listeria monocytogenes, to induce sepsis in experimental animals (males, 24 months of age) and subjected experimental animals to a standard clinical protocol of 3 doses of ampicillin i.p. and 14 days of amoxicillin added to the drinking water. NVC responses, endothelial function and cognitive performance were measured in septic and age-matched control groups within 14 days after the final antibiotic treatment. Our data demonstrate that sepsis in aging significantly impairs NVC responses measured in somatosensory cortex during whisker stimulation, significantly impairs endothelial function in isolated and pressure cannulated aorta rings in response to acetylcholine stimulation. No significant impairment of cognitive function in post-sepsis aged animals has been observed when measured using the PhenoTyper homecage based system. Our findings suggest that sepsis-associated endothelial dysfunction and impairment of NVC responses may contribute to long-term cognitive deficits in older sepsis survivors.

Susceptibility for Some Infectious Diseases in Patients With Diabetes: The Key Role of Glycemia

Uncontrolled diabetes results in several metabolic alterations including hyperglycemia. Indeed, several preclinical and clinical studies have suggested that this condition may induce susceptibility and the development of more aggressive infectious diseases, especially those caused by some bacteria (including Chlamydophila pneumoniae, Haemophilus influenzae, and Streptococcus pneumoniae, among others) and viruses [such as coronavirus 2 (CoV2), Influenza A virus, Hepatitis B, etc.]. Although the precise mechanisms that link glycemia to the exacerbated infections remain elusive, hyperglycemia is known to induce a wide array of changes in the immune system activity, including alterations in: (i) the microenvironment of immune cells (e.g., pH, blood viscosity and other biochemical parameters); (ii) the supply of energy to infectious bacteria; (iii) the inflammatory response; and (iv) oxidative stress as a result of bacterial proliferative metabolism. Consistent with this evidence, some bacterial infections are typical (and/or have a worse prognosis) in patients with hypercaloric diets and a stressful lifestyle (conditions that promote hyperglycemic episodes). On this basis, the present review is particularly focused on: (i) the role of diabetes in the development of some bacterial and viral infections by analyzing preclinical and clinical findings; (ii) discussing the possible mechanisms by which hyperglycemia may increase the susceptibility for developing infections; and (iii) further understanding the impact of hyperglycemia on the immune system.

Pathogenic Differences of Type 1 Restriction-Modification Allele Variants in Experimental Listeria monocytogenes Meningitis

Background: L. monocytogenes meningoencephalitis has a mortality rate of up to 50% and neurofunctional sequelae are common. Type I restriction-modification systems (RMS) are capable of adding methyl groups to the host genome. Some contain multiple sequence recognition (hsdS) genes that recombine, resulting in distinct DNA methylation patterns and patterns of gene expression. These phenotypic switches have been linked to virulence and have recently been discovered in multiple clonal complexes of L. monocytogenes. In the present study, we investigated the significant of RMS on L. monocytogenes virulence during the acute phase of experimental meningitis. Methods: L. monocytogenes strains containing RMS systems were identified, and purified clones enriched for single hsdS alleles were isolated. In vivo, 11-day old Wistar rats were infected with an inoculum containing (a) one of 4 single RMS allele variants (A, B, C, D) treated with amoxicillin (AMX 50 mg/kg/dosis, q8h), (b) a mixture of all 4 variants with or without AMX treatment, or (c) different mixtures of 2 RMS allele variants. At selected time points after infection, clinical and inflammatory parameters, bacterial titers and brain damage were determined. Changes in the relative frequency of the occurring RMS alleles in the inoculum and in CSF or cerebellum of infected animals were analyzed by capillary electrophoresis. Results: We have identified a phase variable RMS locus within L. monocytogenes CC4 and generated stocks that stably expressed each of the possible hsdS genes within that loci. Generation of these allele variants (A, B, C, D) allowed us to determine the methylation pattern associated with each hsdS through SMRT sequencing. In vivo infections with these single allele variants revealed differences in disease severity in that C induced the worst clinical outcome and more pronounced hippocampal apoptosis; D showed the most pronounced weight loss and the highest bacterial titer in the cerebellum. A caused the least severe disease. Conclusion: We identified that L. monocytogenes expressing hsdS (A) causes less damage than when other hsdS genes are expressed. While expression of hsdSC and D worsened the outcome in L. monocytogenes meningitis. We also demonstrate a competitive advantage of variants C and B over variant A in this model. Phenotypical switching may therefore represent a mechanism of virulence regulation during the acute phase of CNS infections with L. monocytogenes.

Post-Transcriptional Inflammatory Response to Intracellular Bacterial c-di-AMP

Cyclic-di-AMP (c-di-AMP) is a bacterial second messenger that is produced by intracellular bacterial pathogens in mammalian host macrophages. Previous reports have shown that c-di-AMP is recognized by intracellular pattern recognition receptors of the innate immune system and stimulate type I interferon response. Here we report that the response to c-di-AMP includes a post-transcriptional component that is involved in the induction of additional inflammatory cytokines including IL-6, CXCL2, CCL3, and CCL4. Their mRNAs contain AU-rich elements (AREs) in their 3' UTR that promote decay and repress translation. We show that c-di-AMP leads to the phosphorylation of p38 MAPK as well as the induction of the ARE-binding protein TTP, both of which are components of a signaling pathway that modulate the expression of ARE-containing mRNAs at the post-transcriptional level. Pharmacological inhibition of p38 reduces the c-di-AMP-dependent release of induced cytokines, while TTP knockdown increases their release and mRNA stability. C-di-AMP can specifically increase the expression of a nano-Luciferase reporter that contains AREs. We propose a non-canonical intracellular mode of activation of the p38 MAPK pathway with the subsequent enhancement in the expression of inflammatory cytokines. C-di-AMP is widely distributed in bacteria, including infectious intracellular pathogens; hence, understanding of its post-transcriptional gene regulatory effect on the host response may provide novel approaches for therapy.

Etiology, clinical presentation, outcome and the effect of initial management in immunocompromised patients with community acquired bacterial meningitis

OBJECTIVES

The aim was to analyze differences in clinical presentation, etiology, management, and outcome between immunocompromised and immunocompetent patients with acute bacterial meningitis (ABM).

METHODS

Data were extracted from 1056 adult ABM patients prospectively registered in the national Swedish quality register for ABM during 2008-2017. Primary endpoint was 30-day mortality and secondary endpoints 90-day mortality and unfavorable outcome.

RESULTS

An immunocompromised state was observed in 352 (33%) of the 1056 patients. Streptococcus pneumoniae dominated in both immunocompromised and immunocompetent patients (53% in both groups), whereas L monocytogenes occurred in 11% and 2%, respectively. The unadjusted odds ratio (OR) for 30-day mortality in immunocompromised compared to immunocompetent patients was 1.68 (95% confidence interval (CI): 1.07-2.63). Adjusted for age, sex, and mental status on admission the OR was 1.34 (CI: 0.82-2.21). Adjusted also for time to antibiotic treatment and corticosteroids the OR was 1.10 (CI: 0.59-2.05), and in patients without Listeria meningitis 0.98 (CI: 0.50-1.90). Although, the ORs were higher for 90-day mortality and unfavorable outcome the effects of adjustments were similar.

CONCLUSION

Mortality in immunocompromised patients with ABM is only moderately increased unless caused by Listeria. This difference is further reduced in patients given early antibiotic treatment and adjunctive corticosteroids.

FUNDING

This work was supported by Stockholm County Council.

Antimicrobial Susceptibility and Antibacterial Mechanism of Limonene against Listeria monocytogenes

Limonene is a monoterpenoid compound, which is founded in a lot of plants’ essential oils with good antibacterial activity against food-borne pathogens, but it has an ambiguous antimicrobial susceptibility and mechanism against Listeria monocytogenes (L. monocytogenes). In this study, the antimicrobial susceptibility of Limonene to L. monocytogenes was studied, and some new sights regarding its antibacterial mechanism were further explored. Scanning electron microscopy (SEM) verified that limonene caused the destruction of the cell integrity and wall structure of L. monocytogenes. The increase in conductivity and the leakage of intracellular biomacromolecules (nucleic acids and proteins) confirmed that limonene had an obvious effect on cell membrane permeability. The results of Propidium Iodide (PI) fluorescence staining were consistent with the results of the conductivity measurements. This indicated that limonene treatment caused damage to the L. monocytogenes cell membrane. Furthermore, the decrease in ATP content, ATPase (Na⁺K⁺-ATPase, Ca²⁺-ATPase) activity and respiratory chain complex activity indicated that limonene could hinder ATP synthesis by inhibiting the activity of the respiratory complex and ATPase. Finally, differential expression of proteins in the respiratory chain confirmed that limonene affected respiration and energy metabolism by inhibiting the function of the respiratory chain complex.

Comparative Analysis of Listeria monocytogenes Plasmids and Expression Levels of Plasmid-Encoded Genes during Growth under Salt and Acid Stress Conditions

Listeria monocytogenes strains are known to harbour plasmids that confer resistance to sanitizers, heavy metals, and antibiotics; however, very little research has been conducted into how plasmids may influence L. monocytogenes’ ability to tolerate food-related stresses. To investigate this, a library (n = 93) of L. monocytogenes plasmid sequences were compared. Plasmid sequences were divided into two groups (G1 and G2) based on a repA phylogeny. Twenty-six unique plasmid types were observed, with 13 belonging to each of the two repA-based groups. G1 plasmids were significantly (p < 0.05) smaller than G2 plasmids but contained a larger diversity of genes. The most prevalent G1 plasmid (57,083 bp) was observed in 26 strains from both Switzerland and Canada and a variety of serotypes. Quantitative PCR (qPCR) revealed a >2-fold induction of plasmid-contained genes encoding an NADH peroxidase, cadmium ATPase, multicopper oxidase, and a ClpL chaperone protein during growth under salt (6% NaCl) and acid conditions (pH 5) and ProW, an osmolyte transporter, under salt stress conditions. No differences in salt and acid tolerance were observed between plasmid-cured and wildtype strains. This work highlights the abundance of specific plasmid types among food-related L. monocytogenes strains, the unique characteristics of G1 and G2 plasmids, and the possible contributions of plasmids to L. monocytogenes tolerance to food-related stresses.

Bacterial Meningitis in Patients using Immunosuppressive Medication: a Population-based Prospective Nationwide Study

We studied occurrence, presentation, disease course, effect of adjunctive dexamethasone, and prognosis of bacterial meningitis in patients using immunosuppressive medication. Patients were selected from our nationwide, prospective cohort on community-acquired bacterial meningitis performed from March 1, 2006 through October 31, 2014. Eighty-seven of 1447 episodes (6 %) of bacterial meningitis occurred in patients using immunosuppressive medication, and consisted of corticosteroids in 82 %. Patients with bacterial meningitis using immunosuppressive medication were less likely to present with headache (P = 0.02) or neck stiffness (P = 0.005), as compared those not on immunosuppressive medication. In 46 % of episodes CSF leukocyte count was below 1000/mm3. CSF cultures revealed S. pneumoniae in 41 % and L. monocytogenes in 40 % of episodes. Outcome was unfavorable in 39 of 87 episodes (45 %) and death occurred in 22 of 87 episodes (25 %). Adjunctive dexamethasone was administered in 52 of 87 (60 %) episodes, and mortality tended to be lower in those on adjunctive dexamethasone therapy as compared to those without dexamethasone therapy (10 of 52 [19 %] vs 12 of 35 [34 %], P = 0.14). We conclude that bacterial meningitis in patients using immunosuppressive medication is likely to present with atypical clinical and laboratory features, and is often caused by atypical bacteria, mainly L. monocytogenes. Adjunctive dexamethasone is widely prescribed in these patients and was not associated with harm in this study.

Genotypes Associated with Listeria monocytogenes Isolates Displaying Impaired or Enhanced Tolerances to Cold, Salt, Acid, or Desiccation Stress

The human pathogen Listeria monocytogenes is a large concern in the food industry where its continuous detection in food products has caused a string of recalls in North America and Europe. Most recognized for its ability to grow in foods during refrigerated storage, L. monocytogenes can also tolerate several other food-related stresses with some strains possessing higher levels of tolerances than others. The objective of this study was to use a combination of phenotypic analyses and whole genome sequencing to elucidate potential relationships between L. monocytogenes genotypes and food-related stress tolerance phenotypes. To accomplish this, 166 L. monocytogenes isolates were sequenced and evaluated for their ability to grow in cold (4°C), salt (6% NaCl, 25°C), and acid (pH 5, 25°C) stress conditions as well as survive desiccation (33% RH, 20°C). The results revealed that the stress tolerance of L. monocytogenes is associated with serotype, clonal complex (CC), full length inlA profiles, and the presence of a plasmid which was identified in 55% of isolates. Isolates with full length inlA exhibited significantly (p < 0.001) enhanced cold tolerance relative to those harboring a premature stop codon (PMSC) in this gene. Similarly, isolates possessing a plasmid demonstrated significantly (p = 0.013) enhanced acid tolerance. We also identified nine new L. monocytogenes sequence types, a new inlA PMSC, and several connections between CCs and the presence/absence or variations of specific genetic elements. A whole genome single-nucleotide-variants phylogeny revealed sporadic distribution of tolerant isolates and closely related sensitive and tolerant isolates, highlighting that minor genetic differences can influence the stress tolerance of L. monocytogenes. Specifically, a number of cold and desiccation sensitive isolates contained PMSCs in σB regulator genes (rsbS, rsbU, rsbV). Collectively, the results suggest that knowing the sequence type of an isolate in addition to screening for the presence of full-length inlA and a plasmid, could help food processors and food agency investigators determine why certain isolates might be persisting in a food processing environment. Additionally, increased sequencing of L. monocytogenes isolates in combination with stress tolerance profiling, will enhance the ability to identify genetic elements associated with higher risk strains.

Genes Associated with Desiccation and Osmotic Stress in Listeria monocytogenes as Revealed by Insertional Mutagenesis

Listeria monocytogenes is a foodborne pathogen whose survival in food processing environments may be associated with its tolerance to desiccation. To probe the molecular mechanisms used by this bacterium to adapt to desiccation stress, a transposon library of 11,700 L. monocytogenes mutants was screened, using a microplate assay, for strains displaying increased or decreased desiccation survival (43% relative humidity, 15°C) in tryptic soy broth (TSB). The desiccation phenotypes of selected mutants were subsequently assessed on food-grade stainless steel (SS) coupons in TSB plus 1% glucose (TSB-glu). Single transposon insertions in mutants exhibiting a change in desiccation survival of >0.5 log CFU/cm(2) relative to that of the wild type were determined by sequencing arbitrary PCR products. Strain morphology, motility, and osmotic stress survival (in TSB-glu plus 20% NaCl) were also analyzed. The initial screen selected 129 desiccation-sensitive (DS) and 61 desiccation-tolerant (DT) mutants, out of which secondary screening on SS confirmed 15 DT and 15 DS mutants. Among the DT mutants, seven immotile and flagellum-less strains contained transposons in genes involved in flagellum biosynthesis (fliP, flhB, flgD, flgL) and motor control (motB, fliM, fliY), while others harbored transposons in genes involved in membrane lipid biosynthesis, energy production, potassium uptake, and virulence. The genes that were interrupted in the 15 DS mutants included those involved in energy production, membrane transport, protein metabolism, lipid biosynthesis, oxidative damage control, and putative virulence. Five DT and 14 DS mutants also demonstrated similar significantly (P < 0.05) different survival relative to that of the wild type when exposed to osmotic stress, demonstrating that some genes likely have similar roles in allowing the organism to survive the two water stresses.

Listeria septicemia accompanied by central nervous system involvement in a patient with multiple myeloma and secondary diabetes

Patient: Female, 58

Final Diagnosis: Listeria septicemia

Symptoms: Nausea • vomitting • high fever • apathetic intelligence • repeated convulsion

Medication: Levofloxacin

Clinical Procedure: —

Specialty: Hematology

Objective: Rare disease

Listeria monocytogenes peritonitis: presentation, clinical features, treatment, and outcome

BACKGROUND

Spontaneous bacterial peritonitis (SBP) is a serious complication in cirrhotic patients. Gram (-) (E. coli, Klebsiella pneumoniae), and Gram (+) (Streptococci, Staphylococci) bacteria are most frequently cultured from patients'ascites. Listeria monocytogenes (Lm) is scarcely reported as a causative agent.

OBJECTIVE

Our objective is to describe Lm peritonitis as a clinical entity, including its presentation, clinical features, treatment, and the potential factors that might affect survival outcome.

DATA SOURCES

MEDLINE, Scholar.Google, Scopus databases, including English, Spanish, French, and German language papers published between 1966 and June 2011, and reference lists.

DATA EXTRACTION

investigators abstracted details about medical history, disease presentation, laboratory data, treatment and outcome.

DATA SYNTHESIS

One-hundred and twenty-eight cases with known survival outcome--eighty-six cirrhotics, seventeen individuals undergoing continuous ambulatory peritoneal dialysis and another twenty-five with other or no underline condition were reviewed. An additional number of twenty-five cases with unknown outcome were searched in Listeria studies published from 1990 to 2009 and were only used for calculating worldwide distribution.

CONCLUSION

Cirrhotics, mostly alcoholics, presented with fever and abdominal pain. Those who succumbed had significantly higher peripheral WBC count (15622 vs. 8155 cells/mm(3), p = 0.01) and (%) polymorphonuclear cells in differential count (83.3 vs. 71%, p = 0.001). Higher mortality was experienced in those with comorbidities, and those who presented with encephalopathy. Lower mortality was experienced in patients on continuous ambulatory peritoneal dialysis. Ascites was neutrocytic in 86% of the samples. In the sum of the cases mortality was 27.3%, with significantly highest rates in the elderly, in patients with bacteremia, immunosuppression, hematological malignancies, and lowest rates in those who presented with abdominal pain and in diabetics (type I or II). The latter observation was surprising and could be considered a single fortuitous fact. Initial appropriate treatment was associated with significantly better outcome (p = 0.002) than inappropriate; combination therapy with an aminoglycoside was superior to monotherapy (p = 0.038).

Meningoencephalitis due to Listeria monocytogenes in a pregnant rhesus macaque (Macaca mulatta)

We here report a spontaneous case of meningoencephalitis due to Listeria monocytogenes in an adult primiparous rhesus macaque (Macaca mulatta) during an outbreak of listeriosis in an outdoor enclosure. Clinical signs included tremors, abnormal posture, and altered mental status. Hematology and analyses of cerebrospinal fluid were consistent with bacterial infection. Pure cultures of L. monocytogenes were recovered from the placenta-abortus, cerebrospinal fluid, and brain tissue. The macaque did not respond to treatment and was euthanized. Histopathologic examination of the brain revealed acute meningoencephalitis. This case represents an unusual clinical and pathologic presentation of listeriosis in a nonhuman primate in which the dam and fetus both were affected.

Infections of the nervous system

Glycemic control is an important aspect of patient care in the surgical Infections of the nervous system are among the most difficult infections in terms of the morbidity and mortality posed to patients, and thereby require urgent and accurate diagnosis. Although viral meningitides are more common, it is the bacterial meningitides that have the potential to cause a rapidly deteriorating condition that the physician should be familiar with. Viral encephalitis frequently accompanies viral meningitis, and can produce focal neurologic findings and cognitive difficulties that can mimic other neurologic disorders. Brain abscesses also have the potential to mimic and present like other neurologic disorders, and cause more focal deficits. Finally, other infectious diseases of the central nervous system, such as prion disease and cavernous sinus thrombosis, are explored in this review.

Epidemiology and clinical characteristics of Listeria monocytogenes bacteremia in a Taiwanese medical center

BACKGROUND/PURPOSE

There have been many reported cases of Listeria monocytogenes bacteremia in Europe and the United States, but only a few from Taiwan. The present study was undertaken to analyze the clinical characteristics of patients with L. monocytogenes bacteremia in Taiwan.

METHODS

Patients with culture-confirmed L. monocytogenes bacteremia were identified at Chang Gung Memorial Hospital between January 2001 and December 2008. The clinical features and outcomes of the patients and the antimicrobial susceptibilities of the clinical isolates were analyzed.

RESULTS

Forty-three patients, including two newborn babies (4.7%) and 41 adults (95.3%), with at least one episode of Listeria bacteremia were identified. Forty-two (97.7%) of these patients had underlying diseases. Thirty-three patients (76.7%) had fever, 14 (32.6%) had experienced respiratory distress, and 11 (25.6%) had reported changes in consciousness. Twelve patients died within 14 days of infection, corresponding to a case-fatality rate of 27.9%. All the clinical isolates tested were susceptible to ampicillin, penicillin and vancomycin.

CONCLUSION

Most cases of L. monocytogenes infection occurred in adults with underlying diseases, especially malignancy, and only two cases of neonatal L. monocytogenes bacteremia were identified over the 8-year period. Penicillin, ampicillin and vancomycin could be used for the treatment of L. monocytogenes bacteremia, with the case-fatality rate lower for patients who received appropriate treatment.

Bacterial meningitis in cirrhotic patients: case series and description of the prognostic role of acute renal failure

AIM

To analyze the mortality risk factors in cirrhotic patients with bacterial meningitis (BM).

BACKGROUND

Cirrhotic patients are susceptible to infections. Despite its high mortality rate, BM has not been extensively studied in this group of patients.

STUDY

BM patients diagnosed with cirrhosis, between 1987 and 2008, were studied. BM was defined as the presence of signs or symptoms of meningitis and a cerebrospinal fluid (CSF) leukocyte count >100/mm3 or the presence of bacteria in CSF.

RESULTS

We identified 4955 infections among 7591 cirrhotic patients; 12 (0.2%) had BM. The mean age at diagnosis was 60±16 years. Abnormal mental status (83%), fever (67%), and neck stiffness (67%) were the most frequent clinical presentations. The sensitivity of CSF culture was 75% (Streptococcus pneumoniae, 2; Staphylococcus aureus, 2; Listeria monocytogenes, 1; Group B Streptococcus, 1; Streptococcus agalactiae, 1; Streptococcus bovis, 1; and Escherichia coli, 1), and its correlation with blood culture was 78%. Five patients died. On admission, the serum creatinine level was 1.63±0.93 mg/dL. A serum creatinine level ≥1.3 mg/dL was associated with increased mortality (P=0.028). The model for end-stage liver disease score, gastrointestinal bleeding, bilirubin level >3.5 mg/dL, hepatic encephalopathy, diabetes mellitus, and results of cytology and biochemistry tests of CSF were not associated with mortality.

CONCLUSIONS

BM in cirrhotic patients is associated with a high mortality rate. The clinical and microbiologic features of BM in cirrhotic patients differ from those in the general population. A serum creatinine level ≥1.3 mg/dL on admission is associated with a higher risk of mortality.

Community-acquired acute bacterial meningitis in the elderly in Turkey

This investigation aimed both to delineate the current status of community-acquired acute bacterial meningitis and to produce data on the interrelationships between clinical, laboratory and therapeutic parameters in the elderly. This retrospective cohort study was conducted in 28 Turkish institutions in 159 culture-positive patients over the age of 50 years. Streptococcus pneumoniae was the most common pathogen (69.2%), followed by Listeria monocytogenes (8.8%). For this reason, antilisterial antibiotics such as ampicillin or benzylpenicillin should be added to the therapeutic regimen. Pathogen-specific mortality did not vary between S. pneumoniae and L. monocytogenes. The overall mortality was 2.5% at the third day, 12.6% at the seventh day, 20.1% at the 14th day and 21.4% at the 21st day. The risk factors for fatality were increasing age, the presence of stupor, sepsis and inappropriate antibiotic administration. Cerebrospinal fluid (CSF) leukocyte counts and CSF/blood glucose ratios were lower in patients who died. Fever did not differ between survivors and fatal cases. The mean duration of antibiotic therapy in survivors was 16.3 +/- 6.4 days. One-fifth of the patients had complications, and in 5.7% of the patients sequelae persisted at follow-up.