Neisseria meningitidis is a commensal of human nasopharynx. In some circumstances, this bacteria can invade the bloodstream and, after crossing the blood brain barrier, the meninges. A filamentous ...phage, designated MDAΦ for Meningococcal Disease Associated, has been associated with invasive disease. In this work we show that the prophage is not associated with a higher virulence during the bloodstream phase of the disease. However, looking at the interaction of N. meningitidis with epithelial cells, a step essential for colonization of the nasopharynx, we demonstrate that the presence of the prophage, via the production of viruses, increases colonization of encapsulated meningococci onto monolayers of epithelial cells. The analysis of the biomass covering the epithelial cells revealed that meningococci are bound to the apical surface of host cells by few layers of heavily piliated bacteria, whereas, in the upper layers, bacteria are non-piliated but surrounded by phage particles which (i) form bundles of filaments, and/or (ii) are in some places associated with bacteria. The latter are likely to correspond to growing bacteriophages during their extrusion through the outer membrane. These data suggest that, as the biomass increases, the loss of piliation in the upper layers of the biomass does not allow type IV pilus bacterial aggregation, but is compensated by a large production of phage particles that promote bacterial aggregation via the formation of bundles of phage filaments linked to the bacterial cell walls. We propose that MDAΦ by increasing bacterial colonization in the mucosa at the site-of-entry, increase the occurrence of diseases.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Human breast milk (HBM) is a source of essential nutrients for infants and is particularly recommended for preterm neonates when their own mother's milk is not available. It provides protection ...against infections and decreases necrotizing enterocolitis and cardiovascular diseases. Nevertheless, HBM spoilage can occur due to contamination by pathogens, and the risk of a shortage of HBM is very often present.
is the most frequent ubiquitous bacteria responsible for HBM being discarded. It can contaminate HBM at all stages, from its collect point to the storage and delivery.
can induce severe infection in newborns with very low birth weight, with sometimes fatal outcomes. Although the source of contamination is rarely identified, in some cases, HBM was suspected as a potential source. Even if the risk is low, as infection due to
in preterm infants should not be overlooked, human milk banks follow strict procedures to avoid contamination, to accurately identify remaining bacteria following pasteurization and to discard non-compliant milk samples. In this review, we present a literature overview of
infections reported in neonates and the suspected sources of contamination. We highlight the procedures followed by the human milk banks from the collection of the milk to its microbiological characterization in Europe. We also present improved detection and decontamination methods that might help to decrease the risk and to preserve the public's confidence in this vital biological product for infants whose mothers cannot breastfeed.
Since the early 1980s, mass spectrometry has emerged as a particularly powerful tool for analysis and characterization of proteins in research. Recently, bacteriologists have focused their attention ...on the use of mass spectrometry (MS) for bacterial identification, especially Matrix Assisted Laser Desorption Ionization Time-Of-Flight (MALDI-TOF). Moreover, recent publications have evaluated MALDI-TOF in microbiology laboratory for routine use. MALDI-TOF-MS is a rapid, precise, and cost-effective method for identification of intact bacteria, compared to conventional phenotypic techniques or molecular biology. Furthermore, it allows identification of bacteria directly from clinical samples (blood cultures for example).
The goal of this review was to update recent data concerning routine identification of microorganisms by MALDI-TOF in the clinical microbiology laboratory.
Delays in the identification of microorganisms are a barrier to the establishment of adequate empirical antibiotic therapy of bacteremia. Matrix-assisted laser desorption ionization-time of flight ...mass spectrometry (MALDI-TOF-MS) allows the identification of microorganisms directly from colonies within minutes. In this study, we have adapted and tested this technology for use with blood culture broths, thus allowing identification in less than 30 min once the blood culture is detected as positive. Our method is based on the selective recovery of bacteria by adding a detergent that solubilizes blood cells but not microbial membranes. Microorganisms are then extracted by centrifugation and analyzed by MALDI-TOF-MS. This strategy was first tested by inoculating various bacterial and fungal species into negative blood culture bottles. We then tested positive patient blood or fluid samples grown in blood culture bottles, and the results obtained by MALDI-TOF-MS were compared with those obtained using conventional strategies. Three hundred twelve spiked bottles and 434 positive cultures from patients were analyzed. Among monomicrobial fluids, MALDI-TOF-MS allowed a reliable identification at the species, group, and genus/family level in 91%, 5%, and 2% of cases, respectively, in 20 min. In only 2% of these samples, MALDI-TOF MS did not yield any result. When blood cultures were multibacterial, identification was improved by using specific databases based on the Gram staining results. MALDI-TOF-MS is currently the fastest technique to accurately identify microorganisms grown in positive blood culture broths.
Cystic fibrosis (CF) is caused by defective Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein. Morbidity is mainly due to early airway infection. We hypothesized that S. aureus ...clearance during the first hours of infection was impaired in CF human Airway Surface Liquid (ASL) because of a lowered pH. The ASL pH of human bronchial epithelial cell lines and primary respiratory cells from healthy controls (WT) and patients with CF was measured with a pH microelectrode. The antimicrobial capacity of airway cells was studied after S. aureus apical infection by counting surviving bacteria. ASL was significantly more acidic in CF than in WT respiratory cells. This was consistent with a defect in bicarbonate secretion involving CFTR and SLC26A4 (pendrin) and a persistent proton secretion by ATP12A. ASL demonstrated a defect in S. aureus clearance which was improved by pH normalization. Pendrin inhibition in WT airways recapitulated the CF airway defect and increased S. aureus proliferation. ATP12A inhibition by ouabain decreased bacterial proliferation. Antimicrobial peptides LL-37 and hBD1 demonstrated a pH-dependent activity. Normalizing ASL pH might improve innate airway defense in newborns with CF during onset of S. aureus infection. Pendrin activation and ATP12A inhibition could represent novel therapeutic strategies to normalize pH in CF airways.
Purpose
We aimed to develop a meropenem population pharmacokinetic (PK) model in critically ill children and simulate dosing regimens in order to optimize patient exposure.
Methods
Meropenem plasma ...concentration was quantified by high-performance liquid chromatography. Meropenem PK was investigated using a non-linear mixed-effect modeling approach.
Results
Forty patients with an age of 16.8 (1.4–187.2) months, weight of 9.1 (3.8–59) kg, and estimated glomerular filtration rate (eGFR) of 151 (19–440) mL/min/1.73 m
2
were included. Eleven patients received continuous replacement renal therapy (CRRT). Concentration-time courses were best described by a two-compartment model with first-order elimination. Body weight (BW), eGFR, and CRRT were covariates explaining the between-subject variabilities on central/peripheral volume of distribution (V1/V2), inter-compartment clearance (
Q
), and clearance (CL): V1
i
= V1
pop
× (BW/70)
1
,
Q
i
=
Q
pop
× (BW/70)
0.75
, V2
i
= V2
pop
× (BW/70)
1
, CL
i
= (CL
pop
× (BW/70)
0.75
) × (eGFR/100)
0.378
) for patients without CRRT and CL
i
= (CL
pop
× (BW/70)
0.75
) × 0.9 for patients with CRRT, where CL
pop
, V1
pop
,
Q
pop
, and V2
pop
are 6.82 L/h, 40.6 L, 1 L/h, and 9.2 L respectively normalized to a 70-kg subject. Continuous infusion, 60 and 120 mg/kg per day, is the most adequate dosing regimen to attain the target of 50%
f
T >
MIC
and 100%
f
T >
MIC
for patients infected by bacteria with high minimum inhibitory concentration (MIC) value (> 4 mg/L) without risk of accumulation except in children with severe renal failure.
Conclusion
Continuous infusion allows reaching the
f
T >
MIC
targets safely in children with normal or increased renal clearance.
To what extent immune responses against the gut flora are compartmentalized within mucosal tissues in homeostatic conditions remains a much-debated issue. We describe here, based on an inducible AID ...fate-mapping mouse model, that systemic memory B cell subsets, including mainly IgM
B cells in spleen, together with IgA
plasma cells in spleen and bone marrow, are generated in mice in the absence of deliberate immunization. While the IgA component appears dependent on the gut flora, IgM memory B cells are still generated in germ-free mice, albeit to a reduced extent. Clonal relationships and renewal kinetics after anti-CD20 treatment reveal that this long-lasting splenic population is mainly sustained by output of B cell clones persisting in mucosal germinal centers. IgM-secreting hybridomas established from splenic IgM memory B cells showed reactivity against various bacterial isolates and endogenous retroviruses. Ongoing activation of B cells in gut-associated lymphoid tissues thus generates a diversified systemic compartment showing long-lasting clonal persistence and protective capacity against systemic bacterial infections.
The incidence of campylobacteriosis has substantially increased over the past decade, notably in France. Secondary localizations complicating invasive infections are poorly described. We aimed to ...describe vascular infection or endocarditis caused by Campylobacter spp. We included 57 patients from a nationwide 5-year retrospective study on Campylobacter spp. bacteremia conducted in France; 44 patients had vascular infections, 12 had endocarditis, and 1 had both conditions. Campylobacter fetus was the most frequently involved species (83%). Antibiotic treatment involved a β-lactam monotherapy (54%) or was combined with a fluoroquinolone or an aminoglycoside (44%). The mortality rate was 25%. Relapse occurred in 8% of cases and was associated with delayed initiation of an efficient antimicrobial therapy after the first symptoms, diabetes, and coexistence of an osteoarticular location. Cardiovascular Campylobacter spp. infections are associated with a high mortality rate. Systematically searching for those localizations in cases of C. fetus bacteremia may be warranted.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Antimicrobial stewardship programs aim at reducing the overuse of broad-spectrum antibiotics such as carbapenems, but their impact remains unclear. We compared the use of carbapenems between ...paediatric and adult subjects admitted to a French tertiary hospital and described the intervention of an antibiotic stewardship team (AST). As part of AST routine activity, all adult and paediatric patients receiving carbapenems are identified in real time using a computer-generated alert system and reviewed by the AST. Data associated with carbapenem prescriptions were extracted for 2 years (2014–2015) and were compared between paediatric and adult wards. Prescription appropriateness (i.e. no clinically suitable narrower spectrum alternative to carbapenem for de-escalation) and AST intervention were analysed. In total, 775 carbapenem prescriptions for 291 children and 262 adults were included. Most patients (95%) had a comordity and 52% had known recent carriage of extended-spectrum beta-lactamase producing
Enterobacteriaceae
(ESBLE). Most carbapenem prescriptions came from intensive care units (
n
= 269, 35%) and were initiated for urinary tract (
n
= 200, 27%), sepsis (
n
= 181, 25%), and lung (
n
= 153, 21%) infections. Carbapenems were initiated empirically in 537 (70%) cases, and an organism was isolated in 523 (67%) cases. Among the isolated organisms, 47% (
n
= 246) were ESBLE and 90% (
n
= 468) were susceptible to carbapenems, but an alternative existed in 61% (
n
= 320) of cases according to antibiotic susceptibility testing. Among prescriptions reviewed by the AST, 39% (
n
= 255) were considered non-appropriate and led to either antibiotic discontinuation (
n
= 47, 7%) or de-escalation (
n
= 208, 32%). Non-appropriate prescriptions were more frequent in paediatric wards (
p
= 0.01) and in microbiologically documented infections (
p
= 0.013), and less observed in immunocompromised patients (
p
= 0.009) or with a known ESBLE carriage (
p
< 0.001). Tailored stewardship programs are essential to better control carbapenem use and subsequent antimicrobial resistance.
Septic critically ill children are at a high risk of inadequate antibiotic exposure, requiring them to undergo therapeutic drug monitoring (TDM). The aim of this study was to describe the use of TDM ...for antibiotics in critically ill children.
The authors conducted a single-center observational study between June and December 2019, with all children treated with antibiotics in a pediatric intensive care unit located in a French university hospital. Standard clinical and laboratory data were recorded. Blood samples were collected for routine laboratory tests, and plasma antibiotic levels were assayed using validated analytical methods.
A total of 209 children received antibiotics. TDM was performed in 58 patients (27.8%) who had a greater mean organ dysfunction (according to the International Pediatric Sepsis Consensus Conference) (3 versus 1 in the non-TDM group; P < 0.05) and were treated with antibiotics for longer. A total of 208 samples were analyzed. The median interquartile range assay turnaround time was 3 (1-5) days, and 48 (46.2%) of the 104 initial antibiotic concentration values were below the pharmacokinetic/pharmacodynamic targets. A total of 34 (46%) of the 74 off-target TDM measurements available before the end of the antibiotic treatment prompted dose adjustment. This dose adjustment increased the proportion of on-target TDM measurements (70% versus 20% without adjustment). Subsequent measurements of the minimum inhibitory concentration showed that the use of the European Committee on Antimicrobial Susceptibility Testing's epidemiological cutoff values led to underestimation of pharmacokinetic/pharmacodynamic target attainment in 10 cases (20%).
TDM seems to be an effective means of optimizing antibiotic exposure in critically ill children. This requires timely plasma antibiotic assays and minimum inhibitory concentration measurements. It is important to define which patients should undergo TDM and how this monitoring should be managed.
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