Search

ΔΕΝ ΔΙΑΤΙΘΕΤΑΙ ΠΕΡΙΛΗΨΗ, Antibiotic resistance undermines the possibility to effectively treat bacterial diseases in humans and animals and it is one of the major global threats for the future. Antimicrobial resistance among commensal Escherichia coli (E. coli) of swine is important because it may constitute a reservoir of antimicrobial resistance genes that could be transferred to pathogenic bacteria. This study aimed to estimate the prevalence of antimicrobial resistance among faecal E. coli from healthy weaning and growing pigs in Greek farms. From 14 farms that were enrolled to this study, 390 isolates of E. coli, 160 from growing pigs and 230 from weaning pigs had been derived. Isolates were tested for susceptibility to 19 antimicrobials belonging to 10 different classes, using disk diffusion method. Extremely high resistance rates were observed for streptomycin, tetracycline, doxycycline, trimethoprim-sulphomeathoxazole, and for the penicillins, ampicillin, ticarcillin and piperacillin. All isolates were susceptible in the combination of a penicillin and β-lactamase inhibitors, in aztreonam and extended-spectrum cephalosporins. The vast majority of the isolates (87%) were multi drug resistant (MDR) and the most common MDR patterns showed resistance in three to four antimicrobial classes. Twenty different antibiotic resistance profiles were observed, the most prevalent was chloramphenicol-trimethoprim/sulphomeathoxazole-tetracycline-doxycycline-streptomycin-ampicillin-ticarcillin-piperacillin (CHL-SXT-TET-DOX-SMN-AMP-TIC-PIP) accounting 44% of the isolates. In each farm one or two AMR profiles were predominating accounting 64-100%, while the antimicrobial resistance index (ARI) was estimated to 0.39 ranging from 0.13 to 0.48 among the studied farms. To analyse the differences observed between the farms, additional information about the antibiotic consumption and the level of biosecurity in the farms is necessary. These findings indicate that resistance to a broad range of antimicrobials was prevalent among faecal E. coli isolates of pigs on studied farms, and that this constitutes a potential reservoir for resistance genes that could spread to gut pathogens.

The increase of multidrug-resistant (MDR) bacteria has renewed interest in old antibiotics, such as minocycline, that can be active against various MDR Gram-negative pathogens. The elimination of minocycline by both kidneys and liver makes it suitable for impaired renal function patients. However, the drawback is the possible elimination of a high amount of drug in the intestines, with potential impact on the digestive microbiota during treatment. This study aimed to predict the potential activity of minocycline against Enterobacterales in the gut after parenteral administration, by combining in vivo and in vitro studies. Total minocycline concentrations were determined by UPLC-UV in the plasma and intestinal content of piglets following intravenous administration. In parallel, the in vitro activity of minocycline was assessed against two Escherichia coli strains in sterilized intestinal contents, and compared to activity in a standard broth. We found that minocycline concentrations were 6–39 times higher in intestinal contents than plasma. Furthermore, minocycline was 5- to 245-fold less active in large intestine content than in a standard broth. Using this PK-PD approach, we propose a preclinical pig model describing the link between systemic and gut exposure to minocycline, and exploring its activity against intestinal Enterobacterales by taking into account the impact of intestinal contents.

Actinomyces turicensis was first identified in 1995. To the best of our knowledge, pleural empyema caused by A. turicensis has never been reported. In the case reported herein, a patient with pleural empyema was treated surgically, and in the bacterial samples, A. turicensis was isolated.

Nucleotide-binding oligomerization domain 2 (NOD2) is an intracellular pattern recognition receptor that senses bacterial peptidoglycan (PGN)-conserved motifs in cytosol and stimulates host immune response. The association of NOD2 mutations with a number of inflammatory pathologies, including Crohn disease (CD), Graft-versus-host disease (GVHD), and Blau syndrome, highlights its pivotal role in host-pathogen interactions and inflammatory response. Stimulation of NOD2 by its ligand (muramyl dipeptide) activates pro- inflammatory pathways such as nuclear factor-kappa B (NF-kappa B), mitogen-activated protein kinases (MAPKs), and Caspase-1. A loss of NOD2 function may result in a failure in the control of microbial infection, thereby initiating systemic responses and aberrant inflammation. Because the ligand of Nod2 is conserved in both gram-positive and gram-negative bacteria, NOD2 detects a wide variety of microorganisms. Furthermore, current literature evidences that NOD2 is also able to control viruses' and parasites' infections. In this review, we present and discuss recent developments about the role of NOD2 in shaping the gut commensal microbiota and pathogens, including bacteria, viruses, and parasites, and the mechanisms by which Nod2 mutations participate in disease occurrence.

The human intestinal microbiota plays a major beneficial role in immune development and resistance to pathogens. The use of antibiotics, however, can cause the spread of antibiotic resistance genes within the resident intestinal microbiota. Important vectors for this are integrons. This review therefore focuses on the integrons in non-pathogenic bacteria as a potential source for the development and persistence of multidrug resistance. Integrons are a group of genetic elements which are assembly platforms that can capture specific gene cassettes and express them. Integrons in pathogenic bacteria have been extensively investigated, while integrons in the intestinal microbiota have not yet gained much attention. Knowledge of the integrons residing in the microbiota, however, can potentially aid in controlling the spread of antibiotic resistance genes to pathogens.

Nasal exposure to the mixture of microbial extracts (MME) after ablactation enhanced airway resistance of newborn mice to Streptococcus pneumoniae (J Physiol Lung Cell Mol Physiol 298: L67, 2010). The present study was addressed to elucidate effective factors responsible for the enhanced innate resistance in the airway of MME-exposed newborn mice. MME exposure significantly increased the amount of pulmonary surfactants (SP-A and SP-D) in the airway. Bronchoalveolar lavage fluid of the exposed mice exhibited greater levels of opsonic activity, thereby enhancing the phagocytic and intracellular killing activities of alveolar macrophages (MØ) against S. pneumoniae. The exposure itself did not increase a complement component C3 and mannan-binding lectin-A (MBL-A) in the airway, whereas intratracheal infection with S. pneumoniae increased the quantity of SP-A, SP-D, C3, and MBL-A in the exposed mice to a significant extent compared with control mice. The exposure enhanced the expression of the class A scavenger MØ receptor with collagenous structure on alveolar MØ and also increased the frequency of major histocompatibility complex II+ CD11c+ cells in the lung; the cells were able to produce IL-10 and transforming growth factor-β in vitro. These results suggest that microbial exposure early in life increases the amounts of SP-A and SP-D and the number of scavenger MØ and also promotes maturation of CD11c+ cells in the airway of newborn mice, which may be involved in airway resistance to S. pneumoniae., 博士（医学）・乙1323号・平成26年3月17日, 発行元の規定により、本文の登録不可。本文は以下のURLを参照 "http://dx.doi.org/10.1152/ajplung.00031.2012"

Healthy individuals possess an immune system comprising physical barriers, innate and acquired immunity as well as the indigenous microflora that populate the body surfaces. The immune system maintains constant vigilance over the body at the cellular level as well as at the interface between the host integument and the resident microflora. However, neoplastic diseases and their treatment often lead to impaired immunity resulting in an increased risk of infections due to viruses, bacteria, fungi, and protozoa. This chapter explores the various aspects of host impairment focusing on the components of immunity and the interplay between them to explain why it is that these patients succumb to infections per se. In so doing, we hope that the reader will be better equipped to understand the risks patients face so as to anticipate potential infectious complications and implement appropriate measures to help attain successful remission of the neoplastic diseases and maintain the best quality of life for the patient.

Commensal microflora engages in a symbiotic relationship with their host, and plays an important role in the development of colorectal cancer (CRC). Pathogenic bacteria promote chronic intestinal inflammation and accelerate tumorigenesis. In sporadic CRC, loss of an effective epithelial barrier occurs at early stage of CRC development. As a result, non-pathogenic bacteria and/or their products infiltrate tumor stroma, drive "tumor-elicited inflammation" and promote CRC progression by activating tumor-associated myeloid and immune cells that produce IL-23 and IL-17. In this article we will summarize the recent advances in understanding the relationship between gut flora and CRC.

The MAM domain‐containing 4 (MAMDC4) protein is associated with the unique endocytotic mechanism observed in the intestine of mammals during the immediate postnatal period. Transcriptional expression of MAMDC4 was substantially upregulated at birth in both the piglet jejunum and ileum and its expression decreases after birth. The protein was found localized specifically to the apical region of the luminal epithelium, however, MAMDC4 protein expression was lost at day 10 and 15 in the jejunum and ileum, respectively, and was not associated with “fetal” enterocyte replacement. Although spatial variation in the subcellular localization of Claudin 1 (CLDN1) was noted at day 3, the loss of MAMDC4 at later stages of development did not appear to have any effect on the tight junction structure. Germ‐free (GF) piglets and piglets whose gastrointestinal flora consists exclusively of Escherichia coli (EC) or Lactobacillus fermentum (LF) maintained MAMDC4 protein expression to 14 days of age in distal regions of the small intestine whereas those with conventionalized intestinal flora (CV) showed no MAMDC4 protein at this age. MAMDC4 protein expression was most pronounced in the LF and GF colonized piglets which showed staining in the epithelial cells at 75% and 95% of the length of the small intestine, respectively, which matched that of the newborn. In contrast, EC animals showed only a low abundance at these regions as well as a discontinuous staining pattern. Collectively these results suggest that maturation of MAMDC4 expression in the porcine epithelium occurs more rapidly than what is reported in previously studied rodent species. Furthermore, intestinal bacterial colonization is a major regulator of MAMDC4 in a manner specific to bacterial species and independent of enterocyte turnover.

The etiopathogenesis of many autoimmune disorders has not been identified. The aim of this paper is to focus on the involvement of bacterial exposure, as an environmental factor, in the pathogenesis of autoimmune pancreatitis (AIP), which is broadly categorized as autoimmune disorders involving pancreatic lesions. Avirulent and/or commensal bacteria, which may have an important role(s) as initiating/progressing factors in the pathogenesis of autoimmune disorder AIP, will be emphasized.

A prospective cohort study of preschool healthy children (3–6 years old) from two distinct socio-economic settings in the Brussels area, Belgium, was conducted during the years 2006–2008. The objectives were to evaluate nasopharyngeal colonization by Streptococcus pneumoniae, Staphylococcus aureus, Moraxella catarrhalis and Haemophilus influenzae at the time of PCV7 vaccine introduction and to assess the socio-economic level impact on flora composition and antibiotic resistance. Three hundred and thirty-three children were included and a total of 830 nasopharyngeal samples were collected together with epidemiological data. Pneumococcal serotypes and antibiotic resistance profiles were determined. Risk factors for carriage and bacterial associations were analysed by multivariate logistic regression. Carriage rates were high for all pathogens. Fifty per cent of the children were colonized at least once with S. aureus, 69% with S. pneumoniae, 67% with M. catarrhalis and 83% with H. influenzae. PCV7 uptake was higher among children from a higher socioeconomic setting and S. pneumoniae serotypes varied accordingly. Children from lower socio-economic schools were more likely to carry M. catarrhalis, S. aureus and antibiotic-resistant S. pneumoniae, including a high proportion of non-typeable pneumococcal strains. Positive associations between S. pneumoniae and H. Influenza, between H. influenzae and M. catarrhalis and between H. influenzae and S. aureus were detected. Our study indicates that nasopharynx flora composition is influenced not only by age but also by socioeconomic settings. A child's nasopharynx might represent a unique dynamic environment modulated by intricate interactions between bacterial species, host immune system and PCV7 immunization.

Los síntomas compatibles con vaginitis y vaginosis, son la causa más frecuente de consulta al ginecólogo. La descarga vaginal abundante y el prurito, constituyen la primera sospecha de estas patologías. Sin embargo, debemos tener presente que el aumento significativo de lactobacilos, conocido como lactobacilosis, puede expresarse también con los mismos síntomas y signos de una vulvovaginitis micótica. Si esta condición se mantiene en el tiempo, puede provocar un grado de acidez anormal en la vagina, y puede llevar a una lisis de las células epiteliales que se conoce como vaginosis citolítica. Este diagnóstico, aunque es poco frecuente, debemos sospecharlo especialmente, en aquellas mujeres que relatan tener múltiples consultas por candidiasis vaginal, con escasa o nula respuesta frente a la terapia antimicótica. The symptoms consistent with vaginitis and vaginosis are the most common cause of the visit to the gynecologist. Heavy vaginal discharge and pruritus are the first suspicion of this pathology. However, the significant increase in lactobacilli, known as lactobacilosis can be expressed also with the same symptoms and signs of a fungal vulvovaginitis. If this condition is maintained overtime, can cause abnormal acidity in the vagina, and may lead to epithelial cell lysis, which is known as cytolytic vaginosis. This diagnosis, although rare, should be suspected especially in women who reported having multiple consultations for vaginal candidiasis, with little or no response to antifungal therapy.

International audience; Objectives Soluble factors released by Bifidobacterium breve C50 (Bb) alleviate the secretion of pro-inflammatory cytokines by immune cells, but their effect on intestinal epithelium remains elusive. To decipher the mechanisms accounting for the cross-talk between bacteria/soluble factors and intestinal epithelium, we measured the capacity of the bacteria, its conditioned medium (Bb-CM) and other Gram(+) commensal bacteria to dampen inflammatory chemokine secretion. Methods TNFα-induced chemokine (CXCL8) secretion and alteration of NF-κB and AP-1 signalling pathways by Bb were studied by EMSA, confocal microscopy and western blotting. Anti-inflammatory capacity was also tested in vivo in a model of TNBS-induced colitis in mice. Results Bb and Bb-CM, but not other commensal bacteria, induced a time and dose-dependent inhibition of CXCL8 secretion by epithelial cells driven by both AP-1 and NF-κB transcription pathways and implying decreased phosphorylation of p38-MAPK and IκB-α molecules. In TNBS-induced colitis in mice, Bb-CM decreased the colitis score and inflammatory cytokine expression, an effect reproduced by dendritic cell conditioning with Bb-CM. Conclusions Bb and secreted soluble factors contribute positively to intestinal homeostasis by attenuating chemokine production. The results indicate that Bb down regulate inflammation at the epithelial level by inhibiting phosphorylations involved in inflammatory processes and by protective conditioning of dendritic cells.

Toll-like receptors (TLR) detect pathogen-associated molecular patterns (PAMP) and play a crucial role in triggering immunity. Due to their large surfaces in direct contact with the environment, mucosal tissues are the major sites of PAMP-TLR signalling. How innate and adaptive immunity are triggered through flagellin-TLR5 interaction is the main focus of the review. In view of recent reports on genetic polymorphism, we will summarize the impact of TLR5 on the susceptibility to mucosal infections and on various immuno-pathologies. Finally, the contribution of TLRs in the induction and maintenance of mucosal homeostasis and commensal discrimination is discussed., Facultad de Ciencias Exactas

Resistance to antimicrobials is an increasing problem in the world of today, and develops faster than man can counter. It is therefore of importance to study metabolic pathways in order to develop new antibiotics, but also to understand how resistance spreads and stabilizes in microbial populations. The commensal flora could be an important factor in the spread of antimicrobial resistance, as drugs aimed at other targets also hit the harmless commensal bacteria. If stable resistance develops in such a population, it could seriously impair a later treatment with the same drug. After a treatment with the macrolide clarithromycin, resistance to this antibiotic increased markedly in the untargeted throat flora, and resistance levels did not recede until at least one year later. Another example of stable resistance can also be seen in sulfonamide resistant Streptococcus pyogenes. Sequence determinations of the dihydropteroate synthase (dhps) gene conferring this resistance revealed a mosaic organisation implying that the it had been brought there by horizontal transfer. Molecular characterization of this gene showed that the sulfonamide resistance was due to mutations of structurally important amino acids in position 65 and 213. The folate synthesis pathway has potential for being exploited further as a drug target. One possible new drug target is hydroxymethyl-dihydropterin pyrophosphokinase (hppk). In the malaria parasite Plasmodium falciparum this enzyme is part of a polyfunctional entity, also encoding dhps. The HPPK part can be separated from DHPS, but that the opposite is not possible. The PfHPPK has two insertions: one also present in other plasmodia, and one apparently unique to P. falciparum. Both are crucial for enzyme activity. To further characterize HPPK, we developed a spectrophotometric activity assay and a method to measure substrate channelling of hydroxymethyl-dihydropterin diphosphate.

Polymorphonuclear neutrophil granulocytes (neutrophils) represent a fundamental component of the innate immune system, forming an efficient barrier against invading microbial pathogens. Neutropenia, a common unwanted side effect of chemotherapy, is associated with infectious complications. The human bone marrow produces an estimated number of 1011 neutrophils per day, and granulopoiesis physiologically takes up two-thirds of the hematopoietic marrow space. The regulation of neutrophil numbers in the steady state remains incompletely understood. More recent evidence, however, suggests that it depends on separate hematopoietic signaling pathways as compared with “emergency granulopoiesis,” elicited by injection of infectious agents into experimental mice.1 A “neutrostat” has been suggested to detect neutrophils released by the marrow (“turnstile” hypothesis) or, alternatively, to measure the number of apoptotic neutrophils phagocytosed by tissue macrophages.2 Indeed, adhesion molecule-deficient mice, whose neutrophils are unable to transmigrate, display pronounced neutrophilia. The underlying mechanism was elegantly shown to represent disinhibited macrophage-derived IL-23 secretion, which, in turn, stimulates TH17-derived IL-17 production. IL-17 boosts G-CSF secretion, which stimulates granulopoiesis.3 Further evidence derived from experiments in macrophage and dendritic cell-deficiency models confirm that phagocytes are able to generate a negative feedback signal for granulopoiesis (reviewed in ref. 2). However, marrow-derived macrophages, but not peritoneal macrophages, secrete G-CSF in a dose-dependent manner upon phagocytosis of apoptotic neutrophils.4 In summary, there is experimental data for both positive and negative regulatory effects of macrophages on steady-state granulopoiesis. A putative neutrostat should ideally sense functional shortages in total neutrophil mass rather than merely quantify ongoing production or consumption. Treatment of experimental mice with anti-neutrophil antibodies effectively depletes neutrophils. Feedback responses include phenomena indistinguishable from a status post application of G-CSF, namely increased neutrophil production and mobilization from the marrow. This robust feedback mechanism has recently been shown to be independent of lymphocytes or NK cells (NOD/SCIDcγ−/− mice), independent of the inflammasome (IL1R/IL1β), independent of the emergency granulopoiesis regulator CEBPβ, but dependent on G-CSF.5,6 G-CSF is the major cytokine regulating granulopoiesis, and G-CSF−/− or G-CSF-R−/− mice display reduced neutrophil numbers (20–30% of normal) in the steady state. However, emergency granulopoiesis can be induced even in G-CSF and GM-CSF doubly deficient mice. The fact that low-level granulopoiesis is preserved in animals with absent G-CSF signaling indicates redundant regulatory mechanisms not only in emergency situations, but also in the steady state. Candidate signaling pathways include receptors of pathogen-associated molecular patterns (PAMPs) provided by commensal flora, which modulates both innate and adaptive immunity. Indeed, functional maturation of granulocytes was demonstrated to be dependent on microbiota-derived ligands of the pattern recognition receptor (PRR) NOD1.7 Moreover, germ-free kept (GF) wild-type mice exhibit even more pronounced neutropenia than G-CSF-deficient animals. Further enhancement of neutropenia in GF mice by neutrophil depleting antibodies induces feedback granulopoiesis similar to control mice, including significantly increased G-CSF levels.5 In summary, study of germ-free mice reveals low-level granulopoiesis with intact feedback loops upon neutropenia. However, analyses of neutropenic TLR4−/− and TRIF−/− mice revealed a dysfunctional regulatory feedback loop including upregulation of G-CSF, while it was preserved in MyD88−/− and TLR2−/− animals. In summary, PRR signaling via TLR4 and its adaptor protein TRIF is indispensable in steady-state granulopoiesis. The TLR4-expressing sensor is sensitive to such an extent that even minute amounts of PAMPs ingested with autoclaved food may be sufficient to convey the neutropenia signal in GF mice. Alternatively, endogenous TLR4 agonists active upon neutrophil depletion may play a role in the GF model. In conclusion, the same highly conserved regulatory mechanisms are responsible for both steady-state and emergency granulopoiesis, and the prevailing apodictic separation has to be given up. Current evidence suggests that granulopoiesis represents a demand-driven process triggered along a continuum, likely by exposure to PAMPs and thereby reflecting the mutual relationship of microbiota and host immunity. Two major questions remain unanswered: (1) Which TLR4-positive cellular compartment represents the neutrostat? The putative neutrostat in the model of induced neutropenia is dependent on TLR4. In a model of LPS-induced emergency granulopoiesis, the sensing cellular elements were not transplantable with whole bone marrow transplantation.8 Deregulated bone marrow stromal cells deficient in RARγ or dicer are sufficient to induce hyperproliferation of myelopoiesis (reviewed in ref. 2), and mesenchymal stromal cells express large amounts G-CSF after TLR4-dependent LPS stimulation.5 However, candidates not only include non-hematopoietic (stromal) marrow components such as MSCs or endothelial cells, but also cellular compartments outside the marrow. (2) Which exogenous or endogenous TLR4 ligands are involved in steady-state granulopoiesis? LPS has been shown to directly signal into the marrow hematopoietic stem and progenitor cell (HSPC) niche and influence the divisional and differential fate of HSC. However, endogenous molecules also activate and/or coactivate TLRs. It is therefore conceivable that very low-level PAMPs may convey signals via endogenously sensitized or modulated TLR4. Further research answering these questions is necessary to completely unravel the phenomenon of steady-state granulopoiesis. A better understanding will help us to treat patients in neutropenia—both associated with chemotherapy and idiopathic. (Fig. 1) Figure 1. Schematic overview over steady-state granulopoiesis. PAMPs (pathogen-associated molecular patterns) may originate from the dense intestinal microflora and bind to PRRs (pattern recognition receptors) expressed by both hematopoietic and ...