Listeria monocytogenes is a model organism for cellular microbiology and host-pathogen interaction studies and an important food-borne pathogen widespread in the environment, thus representing an ...attractive model to study the evolution of virulence. The phylogenetic structure of L. monocytogenes was determined by sequencing internal portions of seven housekeeping genes (3,288 nucleotides) in 360 representative isolates. Fifty-eight of the 126 disclosed sequence types were grouped into seven well-demarcated clonal complexes (clones) that comprised almost 75% of clinical isolates. Each clone had a unique or dominant serotype (4b for clones 1, 2 and 4, 1/2b for clones 3 and 5, 1/2a for clone 7, and 1/2c for clone 9), with no association of clones with clinical forms of human listeriosis. Homologous recombination was extremely limited (r/m<1 for nucleotides), implying long-term genetic stability of multilocus genotypes over time. Bayesian analysis based on 438 SNPs recovered the three previously defined lineages, plus one unclassified isolate of mixed ancestry. The phylogenetic distribution of serotypes indicated that serotype 4b evolved once from 1/2b, the likely ancestral serotype of lineage I. Serotype 1/2c derived once from 1/2a, with reference strain EGDe (1/2a) likely representing an intermediate evolutionary state. In contrast to housekeeping genes, the virulence factor internalin (InlA) evolved by localized recombination resulting in a mosaic pattern, with convergent evolution indicative of natural selection towards a truncation of InlA protein. This work provides a reference evolutionary framework for future studies on L. monocytogenes epidemiology, ecology, and virulence.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The ability to cross host barriers is an essential virulence determinant of invasive microbial pathogens. Listeria monocytogenes is a model microorganism that crosses human intestinal and placental ...barriers, and causes severe maternofetal infections by an unknown mechanism. Several studies have helped to characterize the bacterial invasion proteins InlA and InlB. However, their respective species specificity has complicated investigations on their in vivo role. Here we describe two novel and complementary animal models for human listeriosis: the gerbil, a natural host for L. monocytogenes, and a knock-in mouse line ubiquitously expressing humanized E-cadherin. Using these two models, we uncover the essential and interdependent roles of InlA and InlB in fetoplacental listeriosis, and thereby decipher the molecular mechanism underlying the ability of a microbe to target and cross the placental barrier.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Two species of Listeria are pathogenic; L. monocytogenes infects humans and animals, and L. ivanovii has been considered to infect ruminants only. We report L. ivanovii-associated gastroenteritis and ...bacteremia in a man. This isolate was indistinguishable from prototypic ruminant strains. L. ivanovii is thus an enteric opportunistic human pathogen.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Pharmacological and clinical data regarding cefoxitin for the treatment of ESBL-producing
Enterobacteriaceae
-related infections are limited. We performed a multicentric prospective cohort study to ...evaluate continuous/prolonged, or intermittent infusion of cefoxitin. We assessed the plasma concentration as a function of the duration of infusion and then performed a simulation of the percentage of patients who would reach the PK/PD targets, set at 100% ƒT
> MIC
or 100% ƒT
>4 MIC
. Eighty-one patients were included. All patients were treated with 6 gr./day. MICs to cefoxitin ranged from 0.5 to 64 mg/L. Sixteen (19.7%) patients were infected with strains with cefoxitin MICs ≥ 8 mg/L. In all patients infected with strains with MICs ≤ 6 mg/L, PK/PD objectives (100% ƒT
> MIC
) were achieved with prolonged or continuous infusion. In contrast, when MICs were 8 mg/L only, continuous infusion was sufficient to achieve the PK/PD objectives (100% ƒT
> MIC
). Extended infusion of cefoxitin is necessary for the treatment of non-UTI ESBL-related infections.
Microbiological diagnosis of central nervous system (CNS) infections is challenging due to limited access to CNS samples, overlap between meningitis and encephalitis, and the multiplicity of ...pathogens potentially involved. We aimed to estimate the impact of a commercial multiplex PCR assay (FilmArray® meningitis/encephalitis) on the management of patients with suspicion of meningitis or encephalitis, in terms of time to diagnosis, antimicrobial agents use, duration of hospitalization, and costs. This prospective observational study was conducted at Saint Joseph Hospital (Paris, France) from December 2016 to December 2017. All CSF samples sent to the microbiology laboratory for suspicion of meningitis and/or encephalitis, with CSF cells count > 5 cells/μL, were tested by meningitis/encephalitis multiplex PCR assay. One hundred thirty patients were included. The multiplex PCR assay was positive in 33 patients (25%). Main pathogens found were Enterovirus (
n
= 12), Varicella-Zoster virus (
n
= 7), Herpes simplex virus-2 (
n
= 6), and
Listeria monocytogenes
(
n
= 3) as main pathogens. The multiplex PCR assay reduced time to microbiological diagnosis by 3.3 ± 1.6 days and allowed an earlier discontinuation of empirical anti-infective drugs in 42 patients (32%) and an earlier hospital discharge in 23 patients (18%), with an estimated saving of 82 hospital days overall, and a management cost reduction of 26,242 € (201 €/patient). The systematic use of the FilmArray® meningitis/encephalitis multiplex PCR assay may allow earlier diagnosis, earlier discontinuation of empirical treatment, reduced duration of stay, and costs reduction.
From 1999 through 2005, the incidence of listeriosis in France declined from 4.5 to 3.5 cases/million persons. In 2006, it increased to 4.7 cases/million persons. Extensive epidemiologic ...investigations of clusters in France have ruled out the occurrence of large foodborne disease outbreaks. In addition, no increase has occurred in pregnancy-associated cases or among persons <60 years of age who have no underlying disease. Increases have occurred mainly among persons >or=60 years of age and appear to be most pronounced for persons >or=70 years of age. In 8 other European countries, the incidence of listeriosis has increased, or remained relatively high, since 2000. As in France, these increases cannot be attributed to foodborne outbreaks, and no increase has been observed in pregnancy-associated cases. European countries appear to be experiencing an increased incidence of listeriosis among persons >or=60 years of age. The cause of this selective increased incidence is unknown.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Antimicrobial resistance is a major concern. Epidemiological studies have demonstrated direct relationships between antibiotic consumption and emergence/dissemination of resistant strains. Within the ...last decade, authors confounded spectrum activity and ecological effects and did not take into account several other factors playing important roles, such as impact on anaerobic flora, biliary elimination and sub-inhibitory concentration. The ecological impact of antibiotics on the gut microbiota by direct or indirect mechanisms reflects the breaking of the resistance barrier to colonization. To limit the impact of antibiotic therapy on gut microbiota, consideration of the spectrum of activity and route of elimination must be integrated into the decision. Various strategies to prevent (antimicrobial stewardship, action on residual antibiotics at colonic level) or cure dysbiosis (prebiotic, probiotic and fecal microbiota transplantation) have been introduced or are currently being developed.
Patients with viral respiratory infections often present symptoms compatible with bloodstream infections. Consequently, the winter period commonly associated with epidemic respiratory illnesses shows ...an increase in the number of blood cultures (BC) and to occasional saturation of automated BC systems. Here, we explored the seasonal variations in BC samples and the potential impact of shortening the incubation time of BC when automated BC systems are close to saturation. A retrospective study was conducted during a 3-year period in 4 hospitals located in the Paris region, France. All aerobic and anaerobic bottles were included, except pediatric bottles and those sampled for suspicion of endocarditis. The number of BC bottles collected during the winter period was compared to the annual baseline. All bottles positive after a 4-day incubation were analyzed regarding clinical and microbiological findings. The number of BC bottles was significantly higher during the winter periods, compared to the annual baseline (up to 14%). A total of 292,349 BC bottles were analyzed with 23,363 (8.0%) positive, including 236 (1%) after a 4-day incubation. Of these 236 bottles, 76 (64.8%) were positive with a contaminant, 78 (33.1%) with a clinically significant microorganism identified for the same patient in the previous 4 days, and only 5 (2.1%) with a clinically significant microorganism not previously identified. Winter periods were associated with a significant increase in BC samples. Shortening the incubation time of BC bottles from 5 to 4 days seems a relevant option when automated BC systems are close to saturation.
Zoonotic species of
Capnocytophaga
genus belong to the oral microbiota of dogs and cats. They may be responsible for serious human infections, mainly after animal bites, with a high mortality rate. ...In France, only few cases have been reported and no multicenter study has been conducted. Our aim was to describe the French epidemiology of
Capnocytophaga
zoonosis. We conducted a multicenter (21 centers) retrospective non-interventional, observational study in France describing the epidemiology of
Capnocytophaga
zoonosis (
C. canimorsus
,
C. cynodegmi
,
C. canis
) over 10 years with regard to clinical and bacteriological data. From 2009 to 2018, 44 cases of
Capnocytophaga
zoonotic infections were described (
C. canimorsus
,
n
= 41;
C. cynodegmi
,
n
= 3). We observed an increase (2.5 times) in the number of cases over the study period (from the first to the last 5 years of the study). The most frequent clinical presentations were sepsis (
n
= 37), skin and soft tissue infections (
n
= 12), meningitis (
n
= 8), osteoarticular infections (
n
= 6), and endocarditis (
n
= 2). About one-third of patients with sepsis went into septic shock. Mortality rate was 11%. Mortality and meningitis rates were significantly higher for alcoholic patients (
p
= 0.044 and
p
= 0.006, respectively). Other comorbidities included smoking, splenectomy, diabetes mellitus, and immunosuppressive therapy are associated to zoonotic
Capnocytophaga
infection. Eighty-two percent of cases involved contact with dogs, mostly included bites (63%). Despite all isolates were susceptible to the amoxicillin-clavulanic acid combination, three of them were resistant to amoxicillin.
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