Biological Activity of Picrorhiza kurroa: A Source of Potential Antimicrobial Compounds against Yersinia enterocolitica.

Yersiniosis, caused by Yersinia enterocolitica, is the third most rampant zoonotic disease in Europe; the pathogen shows high antibiotic resistance. Herbs have multiple anti-microbial components that reduce microorganism resistance. Therefore, an extract of Picrorhiza kurroa (P. kurroa) was evaluated for potential antimicrobial activity. We report that the ethanolic extract of P. kurroa showed effective antimicrobial activity (zone of inhibition: 29.8 mm, Minimum inhibitory concentration (MIC): 2.45 mg/mL, minimum bactericidal concentration (MBC): 2.4 mg/mL) against Yersinia enterocolitica. Potential bioactive compounds from P. kurroa were identified using LC-MS, namely, cerberidol, annonidine A, benzyl formate, picroside-1, and furcatoside A. P. kurroa showed effective antimicrobial potential in skim milk at different pH, acidity, and water activity levels. P. kurroa affected the physiology of Yersinia enterocolitica and reduced the number of live cells. Yersinia enterocolitica, when incubated with P. kurroa extract, showed lower toxin production. Picroside-1 was isolated and showed higher antimicrobial potential in comparison to the standard antibiotic. Picroside-1 lysed the Yersinia enterocolitica cells, as observed under scanning electron microscopy. Docking revealed that picroside-1 (ligand) showed both hydrophilic and hydrophobic interactions with the dihydrofolate reductase (DHFR) protein of Yersinia enterocolitica and that DHFR is a possible drug target. The high activity and natural origin of Picroside-1 justify its potential as a possible drug candidate for Yersinia enterocolitica.

Biologically synthesized silver nanoparticles, mediated by Bothriochloa laguroides, inhibit biofilm formation and eradicate mature biofilm of Yersinia enterocolitica and Staphylococcus aureus.

AIMS: To phytosynthesize silver nanoparticles (AgNPs) and determine their antibacterial and antibiofilm capacity against gram-positive and gram-negative bacterial strains. METHODS AND RESULTS: AgNPs were synthesized using Bothriochloa laguroides aqueous extract as reducing and stabilizing agent. After characterization, a phytochemical screening to the extract and the AgNPs was performed. Antibacterial activity, inhibition and eradication of biofilms against Staphylococcus aureus and Yersinia enterocolitica strains were tested. Spherical AgNPs with an average size of 8 nm were obtained. Tannins, flavonoids, carbohydrates, proanthocyanidins, anthocyanins and saponins were identified in aqueous extract; meanwhile, only carbohydrates were identified in AgNPs. The MIC and MBC were determined at pmol L-1  levels for all tested strains. Furthermore, AgNPs inhibited more than 90% of biofilms formation and eradicated more than 80% of mature biofilms at concentrations higher than MIC. CONCLUSIONS: The AgNPs obtained in this study inhibited planktonic and sessile growth, and eradicated mature biofilms of pathogenic bacterial strains at very low concentrations. SIGNIFICANCE AND IMPACT OF STUDY: The current study showed the promising potential of AgNPs as antibiofilm agents opening the way for the future development of a new class of antibacterial products.

BtuB-Dependent Infection of the T5-like Yersinia Phage ϕR2-01.

Yersinia enterocolitica is a food-borne Gram-negative pathogen responsible for several gastrointestinal disorders. Host-specific lytic bacteriophages have been increasingly used recently as an alternative or complementary treatment to combat bacterial infections, especially when antibiotics fail. Here, we describe the proteogenomic characterization and host receptor identification of the siphovirus vB_YenS_ϕR2-01 (in short, ϕR2-01) that infects strains of several Yersinia enterocolitica serotypes. The ϕR2-01 genome contains 154 predicted genes, 117 of which encode products that are homologous to those of Escherichia bacteriophage T5. The ϕR2-01 and T5 genomes are largely syntenic, with the major differences residing in areas encoding hypothetical ϕR2-01 proteins. Label-free mass-spectrometry-based proteomics confirmed the expression of 90 of the ϕR2-01 genes, with 88 of these being either phage particle structural or phage-particle-associated proteins. In vitro transposon-based host mutagenesis and ϕR2-01 adsorption experiments identified the outer membrane vitamin B12 receptor BtuB as the host receptor. This study provides a proteogenomic characterization of a T5-type bacteriophage and identifies specific Y. enterocolitica strains sensitive to infection with possible future applications of ϕR2-01 as a food biocontrol or phage therapy agent.

Properties of Two Broad Host Range Phages of Yersinia enterocolitica Isolated from Wild Animals.

Yersinia (Y.) enterocolitica and Y. pseudotuberculosis are important zoonotic agents which can infect both humans and animals. To combat these pathogens, the application of strictly lytic phages may be a promising tool. Since only few Yersinia phages have been described yet, some of which demonstrated a high specificity for certain serotypes, we isolated two phages from game animals and characterized them in terms of their morphology, host specificity, lytic activity on two bio-/serotypes and genome composition. The T7-related podovirus vB_YenP_Rambo and the myovirus vB_YenM_P281, which is very similar to a previously described phage PY100, showed a broad host range. Together, they lysed all the 62 tested pathogenic Y. enterocolitica strains belonging to the most important bio-/serotypes in Europe. A cocktail containing these two phages strongly reduced cultures of a bio-/serotype B4/O:3 and a B2/O:9 strain, even at very low MOIs (multiplicity of infection) and different temperatures, though, lysis of bio-/serotype B2/O:9 by vB_YenM_P281 and also by the related phage PY100 only occurred at 37 °C. Both phages were additionally able to lyse various Y. pseudotuberculosis strains at 28 °C and 37 °C, but only when the growth medium was supplemented with calcium and magnesium cations.

Micro and nanoemulsions of Carissa spinarum fruit polyphenols, enhances anthocyanin stability and anti-quorum sensing activity: Comparison of degradation kinetics.

The low stability of anthocyanins is a constraint in the food industry. The present work has been carried out to overcome this low stability by encapsulating fruit concentrate of underutilized plant Carissa spinarum (CS) with polyphenols in microemulsions (CSME) and nanoemulsions (CSNE). Increasing the amount of CS reduced the particle size from 1154 to 70-300 nm whereas addition of Tween 80 reduced it optimally to 5-25 nm. Degradation of anthocyanins in control and ME/NE proceeded with zero- and first-order reaction rates, respectively, at 28 °C (half-life 6, 25 and 40 days, respectively). The degradation kinetics of phenolics-flavonoids were also studied. CSNE exhibited higher anti-quorum sensing (QS) activity than CSME against Chromobacterium violaceum (73.7%); it inhibited biofilm formation by 70.1 and 64.4% in Pseudomonas aeruginosa, and Yersinia enterocolitica, respectively. This is the first report of using the more stable ME/NE to study anti-QS activity, an alternative to conventional antibiotics.

Structure elucidation and antimicrobial activities of five compounds from Artemisia integrifolia L.

A new compound, integracid (1), together with four known compounds were isolated from the dichloromethane (CH2Cl2) extract from Artemisia integrifolia L. The structures of compounds (1-5) were elucidated by spectroscopic methods, including ultraviolet, infrared (IR), high resolution-electrospray ionization-mass spectrometry (HR-ESI-MS) and extensive one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) techniques, and by comparison with data reported in the references. Antibacterial activities of the compounds were evaluated against various bacteria.

Encapsulation of cinnamon oil in cyclodextrin nanosponges and their potential use for antimicrobial food packaging.

The main goal of this work is the encapsulation of cinnamon essential oil in cyclodextrin nanosponges and the assessment of their antimicrobial activity against foodborne pathogens. After nanosponge synthesis, a headspace-solid phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME-GC-MS) method was validated to quantify essential oil major compounds. Results showed that essential oil was successfully encapsulated in cyclodextrin nanosponges with α-NS and ß-NS being able to encapsulate higher essential oil amounts. Cinnamon essential oil, alone and encapsulated in nanosponges, proved to have antimicrobial activity against foodborne bacteria. Time-kill assays proved that the essential oil, alone or encapsulated, had a bacteriostatic effect against all bacteria tested, with the exception of Y. enterocolitica where a bactericidal action was observed. Furthermore, the controlled release achieved by its encapsulation, allowed cinnamon essential oil to be effective at a much lower concentration in culture medium than when solely dissolved in culture medium. Thus, the results described herein encourage the use of cyclodextrin nanosponges as encapsulating agents for active food packaging applications.

A surrogate structural platform informed by ancestral reconstruction and resurrection of a putative carbohydrate binding module hybrid illuminates the neofunctionalization of a pectate lyase.

Yersinia enterocolitica is a pectinolytic zoonotic foodborne pathogen, the genome of which contains pectin-binding proteins and several different classes of pectinases, including polysaccharide lyases (PLs) and an exopolygalacturonase. These proteins operate within a coordinated pathway to completely saccharify homogalacturonan (HG). Polysaccharide lyase family 2 (PL2) is divided into two major subfamilies that are broadly-associated with contrasting 'endolytic' (PL2A) or 'exolytic' (PL2B) activities on HG. In the Y. enterocolitica genome, the PL2A gene is adjacent to an independent carbohydrate binding module from family 32 (YeCBM32), which possesses a N-terminal secretion tag and is known to specifically bind HG. Independent CBMs are rare in nature and, most commonly, are fused to enzymes in order to potentiate catalysis. The unconventional gene architecture of YePL2A and YeCBM32, therefore, may represent an ancestral relic of a fission event that decoupled PL2A from its cognate CBM. To provide further insight into the evolution of this pectinolytic locus and the molecular basis of HG depolymerisation within Y. enterocolitica, we have resurrected a YePL2A-YeCBM32 chimera and demonstrated that the extant PL2A digests HG more efficiently. In addition, we have engineered a tryptophan from the active site of the exolytic YePL2B into YePL2A (YePL2A-K291W) and demonstrated, using X-ray crystallography of substrate complexes, that it is a structural determinant of exo-activity within the PL2 family. In this manner, surrogate structural platforms may assist in the study of phylogenetic relationships informed by extant and resurrected sequences, and can be used to overcome challenging structural problems within carbohydrate active enzyme families.

Effectiveness of aqueous and hydroalcoholic extracts of Acanthospermum australe (Loefl) Kuntze against diarrhea-inducing bacteria / Eficácia de extratos aquosos e hidroalcoólicos de Acanthospermum australe (Loefl) Kuntze contra bactérias indutoras de diarreia

Abstract Leaves and roots of Acanthospermum australe (Asteraceae) have been used in Brazilian folk medicine for the treatment of various ailments including diarrhea, skin diseases, blennorrhagia, dyspepsia, parasitic worms and malaria. The aim of study was to characterize the chemical profiles of the aqueous and hydroalcoholic extracts of leaves and roots of A. australe, and to evaluate their antimicrobial activities against diarrhea-inducing bacteria (Enterococcus faecalis, Shigella dysenteriae and Yersinia enterocolitica), as well as their cytotoxic properties. Aqueous leaf extracts were obtained by infusion, while aqueous root extracts were obtained by decoction. The hydroalcoholic leaf and root extracts were prepared by maceration in 90% ethanol for 3 days. Antimicrobial activity was assessed using standard techniques and cytotoxicity was evaluated using Chinese hamster ovary cells CHO-K1. Chemical analysis revealed the presence of tannins, flavonoids, saponins and phenolic compounds in the extracts. Although root extracts were not effective against E. faecalis, leaf extracts at concentrations of 20 mg/mL exhibited bactericidal activities against this microorganism. The hydroalcoholic root extract was unique in presenting a bactericidal effect against S. dysenteriae. None of the extracts showed bacteriostatic or bactericidal activities against Y. enterocolitica. The results presented herein demonstrate that the Gram-positive E. faecalis and the Gram-negative S. dysenteriae were susceptible to A. australe extracts, although bacteriostatic/bactericidal activities were only observed at concentrations considered too high for clinical application. Our results support the ethnopharmacological use of A. australe in the treatment of gastrointestinal disorders, particularly diarrhea caused by infectious bacteria, although further studies are required to determine the anti-diarrhea effects and the toxicities of the extracts in vivo.

Resumo Folhas e raízes de Acanthospermum australe (Asteraceae) têm sido usadas na medicina popular brasileira para o tratamento de várias doenças, incluindo diarreia, doenças de pele, blenorragia, dispepsia, vermes parasitas e malária. O objetivo deste estudo foi caracterizar os perfis químicos dos extratos aquosos e hidroalcoólicos das raízes e folhas de A. australe, e avaliar as suas atividades antimicrobianas contra as bactérias indutoras de diarreia (Enterococcus faecalis, Shigella dysenteriae e Yersinia enterocolitica), bem como sua citotoxicidade. Os extratos aquosos de folhas foram obtidos por infusão, enquanto que os extratos aquosos de raízes foram obtidos por decocção. Os extratos hidroalcoólicos de folhas e raízes foram preparados por maceração em etanol a 90% durante 3 dias. A atividade antimicrobiana foi avaliada utilizando técnicas padrão e a citotoxicidade foi avaliada utilizando células de ovário de hamster chinês CHO-K1. A análise química revelou a presença de taninos, flavonóides, saponinas e compostos fenólicos nos extratos. Apesar de extratos de raiz não foram eficazes contra E. faecalis, extratos de folhas em concentrações de 20 mg/mL apresentaram atividades bactericidas contra este microrganismo. O extrato hidroalcoólico de raiz foi o único a apresentar um efeito bactericida contra S. dysenteriae. Nenhum dos extratos apresentaram atividades bacteriostáticas ou bactericidas contra Y. enterocolitica. Os resultados apresentados demonstram que a bactéria Gram-positiva E. faecalis e a Gram-negativa S. dysenteriae foram suscetíveis aos extratos de A. australe, embora as atividades bacteriostáticos/bactericidas tenham sido apenas observados em concentrações consideradas elevadas para aplicação clínica. Os nossos resultados apoiam a utilização de etnofarmacológica de A. australe no tratamento de perturbações gastrointestinais, especialmente diarreia causadas por bactérias infecciosas, embora sejam necessários mais estudos para determinar os efeitos anti-diarreia e as toxicidades dos extratos in vivo.

Sequential Elution of Essential Oil Constituents during Steam Distillation of Hops (Humulus lupulus L.) and Influence on Oil Yield and Antimicrobial Activity.

The profile and bioactivity of hops (Humulus lupulus L.) essential oil, a complex natural product extracted from cones via steam distillation, depends on genetic and environmental factors, and may also depend on extraction process. We hypothesized that compound mixtures eluted sequentially and captured at different timeframes during the steam distillation process of whole hop cones would have differential chemical and bioactivity profiles. The essential oil was collected sequentially at 8 distillation time (DT) intervals: 0-2, 2-5, 5-10, 10-30, 30-60, 60-120, 120-180, and 180-240 min. The control was a 4-h non-interrupted distillation. Nonlinear regression models described the DT and essential oil compounds relationship. Fractions yielded 0.035 to 0.313% essential oil, while control yielded 1.47%. The oil eluted during the first hour was 83.2%, 9.6% during the second hour, and only 7.2% during the second half of the distillation. Essential oil (EO) fractions had different chemical profile. Monoterpenes were eluted early, while sequiterpenes were eluted late. Myrcene and linalool were the highest in 0-2 min fraction, ß-caryophyllene, ß-copaene, ß-farnesene, and α-humulene were highest in fractions from middle of distillation, whereas α- bergamotene, γ-muurolene, ß- and α-selinene, γ- and δ-cadinene, caryophyllene oxide, humulne epoxide II, τ-cadinol, and 6-pentadecen-2-one were highest in 120-180 or 180-240 min fractions. The Gram-negative Escherichia coli was strongly inhibited by essential oil fractions from 2-5 min and 10-30 min, followed by oil fraction from 0-2 min. The strongest inhibition activity against Gram-negative Yersinia enterocolitica, and Gram-positive Clostridium perfringens, Enterococcus faecalis, and Staphylococcus aureus subs. aureus was observed with the control essential oil. This is the first study to describe significant activity of hops essential oils against Trypanosoma brucei, a parasitic protozoan that causes African trypanosomiasis (sleeping sickness in humans and nagana in other animals). Hops essential oil fractions or whole oil may be used as antimicrobial agents or for the development of new drugs.

Effectiveness of aqueous and hydroalcoholic extracts of Acanthospermum australe (Loefl.) Kuntze against diarrhea-inducing bacteria.

Leaves and roots of Acanthospermum australe (Asteraceae) have been used in Brazilian folk medicine for the treatment of various ailments including diarrhea, skin diseases, blennorrhagia, dyspepsia, parasitic worms and malaria. The aim of study was to characterize the chemical profiles of the aqueous and hydroalcoholic extracts of leaves and roots of A. australe, and to evaluate their antimicrobial activities against diarrhea-inducing bacteria (Enterococcus faecalis, Shigella dysenteriae and Yersinia enterocolitica), as well as their cytotoxic properties. Aqueous leaf extracts were obtained by infusion, while aqueous root extracts were obtained by decoction. The hydroalcoholic leaf and root extracts were prepared by maceration in 90% ethanol for 3 days. Antimicrobial activity was assessed using standard techniques and cytotoxicity was evaluated using Chinese hamster ovary cells CHO-K1. Chemical analysis revealed the presence of tannins, flavonoids, saponins and phenolic compounds in the extracts. Although root extracts were not effective against E. faecalis, leaf extracts at concentrations of 20 mg/mL exhibited bactericidal activities against this microorganism. The hydroalcoholic root extract was unique in presenting a bactericidal effect against S. dysenteriae. None of the extracts showed bacteriostatic or bactericidal activities against Y. enterocolitica. The results presented herein demonstrate that the Gram-positive E. faecalis and the Gram-negative S. dysenteriae were susceptible to A. australe extracts, although bacteriostatic/bactericidal activities were only observed at concentrations considered too high for clinical application. Our results support the ethnopharmacological use of A. australe in the treatment of gastrointestinal disorders, particularly diarrhea caused by infectious bacteria, although further studies are required to determine the anti-diarrhea effects and the toxicities of the extracts in vivo.

Secondary focal form of yersinia enterocolitica infection with prolonged polyarthritis in young caucasian male: a case report.

Current issue deals with an interesting clinical case of a rare infectious disease in a Caucasian young male patient, caused by Yersinia enterocоlitica. Infection proceeded in the development of secondary focal form, which was accompanied by prolonged polyarthritis. We described a clinical case of secondary focal form with prolonged polyarthritis caused by Y. enterocolitica O:3 serogroup in young patient with the purpose of focusing on the early clinical and laboratory diagnosistics of Yersiniosis that would minimize the role of medical errors in diagnostics made by general practitioners. This case deserves the attention of internal medicine specialists, physicians of the specialty ≪general practitioners≫, rheumatologists, infectious disease specialists taking into consideration the clinics and immunopathogenesis, as well as a high evidence of a prolonged clinical course and chronicity of this disease. It has accented on the feasibility of early serological diagnostics and etiotropic antibiotic therapy of the disease.

Antimicrobial Use for and Resistance of Zoonotic Bacteria Recovered from Nonhuman Primates.

As a growing threat to human and animal health, antimicrobial resistance (AMR) has become a central public-health topic. Largescale surveillance systems, such as the National Antimicrobial Resistance Monitoring System (NARMS), are now established to monitor and provide guidance regarding AMR, but comprehensive literature on AMR among NHP is sparse. This study provides data regarding current antimicrobial use strategies and the prevalence of AMR in zoonotic bacteria recovered from NHP within biomedical research institutions. We focused on 4 enteric bacteria: Shigella flexneri, Yersinia enterocolitica, Y. pseudotuberculosis, and Campylobacter jejuni. Fifteen veterinarians, 7 biomedical research institutions, and 4 diagnostic laboratories participated, providing susceptibility test results from January 2012 through April 2015. Veterinarians primarily treated cases caused by S. flexneri, Y. enterocolitica, and Y. pseudotuberculosis with enrofloxacin but treated C. jejuni cases with azithromycin and tylosin. All isolates were susceptible to the associated primary antimicrobial but often showed resistance to others. Specifically, S. flexneri isolates frequently were resistant to erythromycin (87.5%), doxycycline (73.7%), and tetracycline (38.3%); Y. enterocolitica isolates to ampicillin (100%) and cefazolin (93.6%); and C. jejuni isolates to methicillin (99.5%) and cephalothin (97.5%). None of the 58 Y. pseudotuber-culosis isolates was resistant to any tested antimicrobial. Notably, resistance patterns were not shared between this study's NHP isolates and human isolates presented by NARMS. Our findings indicate that zoonotic bacteria from NHP diagnostic samples are broadly susceptible to the antimicrobials used to treat the clinical infections. These results can help veterinarians ensure effective antimicrobial therapy and protect staff by minimizing occupational risk.

Identifying components required for OMP biogenesis as novel targets for antiinfective drugs.

The emergence of multiresistant Gram-negative bacteria requires new therapies for combating bacterial infections. Targeting the biogenesis of virulence factors could be an alternative strategy instead of killing bacteria with antibiotics. The outer membrane (OM) of Gram-negative bacteria acts as a physical barrier. At the same time it facilitates the exchange of molecules and harbors a multitude of proteins associated with virulence. In order to insert proteins into the OM, an essential oligomeric membrane-associated protein complex, the ß-barrel assembly machinery (BAM) is required. Being essential for the biogenesis of outer membrane proteins (OMPs) the BAM and also periplasmic chaperones may serve as attractive targets to develop novel antiinfective agents. Herein, we aimed to elucidate which proteins belonging to the OMP biogenesis machinery have the most important function in granting bacterial fitness, OM barrier function, facilitating biogenesis of dedicated virulence factors and determination of overall virulence. To this end we used the enteropathogen Yersinia enterocolitica as a model system. We individually knocked out all non-essential components of the BAM (BamB, C and E) as well as the periplasmic chaperones DegP, SurA and Skp. In summary, we found that the most profound phenotypes were produced by the loss of BamB or SurA with both knockouts resulting in significant attenuation or even avirulence of Ye in a mouse infection model. Thus, we assume that both BamB and SurA are promising targets for the development of new antiinfective drugs in the future.

KdgF, the missing link in the microbial metabolism of uronate sugars from pectin and alginate.

Uronates are charged sugars that form the basis of two abundant sources of biomass-pectin and alginate-found in the cell walls of terrestrial plants and marine algae, respectively. These polysaccharides represent an important source of carbon to those organisms with the machinery to degrade them. The microbial pathways of pectin and alginate metabolism are well studied and essentially parallel; in both cases, unsaturated monouronates are produced and processed into the key metabolite 2-keto-3-deoxygluconate (KDG). The enzymes required to catalyze each step have been identified within pectinolytic and alginolytic microbes; yet the function of a small ORF, kdgF, which cooccurs with the genes for these enzymes, is unknown. Here we show that KdgF catalyzes the conversion of pectin- and alginate-derived 4,5-unsaturated monouronates to linear ketonized forms, a step in uronate metabolism that was previously thought to occur spontaneously. Using enzyme assays, NMR, mutagenesis, and deletion of kdgF, we show that KdgF proteins from both pectinolytic and alginolytic bacteria catalyze the ketonization of unsaturated monouronates and contribute to efficient production of KDG. We also report the X-ray crystal structures of two KdgF proteins and propose a mechanism for catalysis. The discovery of the function of KdgF fills a 50-y-old gap in the knowledge of uronate metabolism. Our findings have implications not only for the understanding of an important metabolic pathway, but also the role of pectinolysis in plant-pathogen virulence and the growing interest in the use of pectin and alginate as feedstocks for biofuel production.

Chicoric acid binds to two sites and decreases the activity of the YopH bacterial virulence factor.

Chicoric acid (CA) is a phenolic compound present in dietary supplements with a large spectrum of biological properties reported ranging from antioxidant, to antiviral, to immunostimulatory properties. Due to the fact that chicoric acid promotes phagocytic activity and was reported as an allosteric inhibitor of the PTP1B phosphatase, we examined the effect of CA on YopH phosphatase from pathogenic bacteria, which block phagocytic processes of a host cell. We performed computational studies of chicoric acid binding to YopH as well as validation experiments with recombinant enzymes. In addition, we performed similar studies for caffeic and chlorogenic acids to compare the results. Docking experiments demonstrated that, from the tested compounds, only CA binds to both catalytic and secondary binding sites of YopH. Our experimental results showed that CA reduces activity of recombinant YopH phosphatase from Yersinia enterocolitica and human CD45 phosphatase. The inhibition caused by CA was irreversible and did not induce oxidation of catalytic cysteine. We proposed that inactivation of YopH induced by CA is involved with allosteric inhibition by interacting with essential regions responsible for ligand binding.

Oral iron acutely elevates bacterial growth in human serum.

Iron deficiency is the most common nutrient deficiency worldwide and routine supplementation is standard policy for pregnant mothers and children in most low-income countries. However, iron lies at the center of host-pathogen competition for nutritional resources and recent trials of iron administration in African and Asian children have resulted in significant excesses of serious adverse events including hospitalizations and deaths. Increased rates of malaria, respiratory infections, severe diarrhea and febrile illnesses of unknown origin have all been reported, but the mechanisms are unclear. We here investigated the ex vivo growth characteristics of exemplar sentinel bacteria in adult sera collected before and 4 h after oral supplementation with 2 mg/kg iron as ferrous sulfate. Escherichia coli, Yersinia enterocolitica and Salmonella enterica serovar Typhimurium (all gram-negative bacteria) and Staphylococcus epidermidis (gram-positive) showed markedly elevated growth in serum collected after iron supplementation. Growth rates were very strongly correlated with transferrin saturation (p < 0.0001 in all cases). Growth of Staphylococcus aureus, which preferentially scavenges heme iron, was unaffected. These data suggest that even modest oral supplements with highly soluble (non-physiological) iron, as typically used in low-income settings, could promote bacteremia by accelerating early phase bacterial growth prior to the induction of immune defenses.

Detection, distribution and characterization of novel superoxide dismutases from Yersinia enterocolitica Biovar 1A.

BACKGROUND: Superoxide dismutases (SODs) cause dismutation of superoxide radicals to hydrogen peroxide and oxygen. Besides protecting the cells against oxidative damage by endogenously generated oxygen radicals, SODs play an important role in intraphagocytic survival of pathogenic bacteria. The complete genome sequences of Yersinia enterocolitica strains show presence of three different sod genes. However, not much is known about the types of SODs present in Y. enterocolitica, their characteristics and role in virulence and intraphagocytic survival of this organism. METHODOLOGY/PRINCIPAL FINDINGS: This study reports detection and distribution of the three superoxide dismutase (sodA, sodB and sodC) genes in 59 strains of Y. enterocolitica and related species. The majority (94%) of the strains carried all three genes and constitutive expression of sodA and sodB was detected in 88% of the strains. Expression of sodC was not observed in any of the strains. The sodA, sodB and sodC genes of Y. enterocolitica were cloned in pET28a (+) vector. Recombinant SodA (82 kDa) and SodB (21 kDa) were expressed as homotetramer and monomer respectively, and showed activity over a broad range of pH (3.0-8.0) and temperature (4-70°C). SodA and SodB showed optimal activity at 4°C under acidic pH of 6.0 and 4.0 respectively. The secondary structures of recombinant SodA and SodB were studied using circular dichroism. Production of YeSodC was not observed even after cloning and expression in E. coli BL21(DE3) cells. A SodA(-) SodB(-) Escherichia coli strain which was unable to grow in medium supplemented with paraquat showed normal growth after complementation with Y. enterocolitica SodA or SodB. CONCLUSIONS/SIGNIFICANCE: This is the first report on the distribution and characterization of superoxide dismutases from Y. enterocolitica. The low pH optima of both SodA and SodB encoded by Y. enterocolitica seem to implicate their role in acidic environments such as the intraphagocytic vesicles.

Hunger for iron: the alternative siderophore iron scavenging systems in highly virulent Yersinia.

Low molecular weight siderophores are used by many living organisms to scavenge scarcely available ferric iron. Presence of at least a single siderophore-based iron acquisition system is usually acknowledged as a virulence-associated trait and a pre-requisite to become an efficient and successful pathogen. Currently, it is assumed that yersiniabactin (Ybt) is the solely functional endogenous siderophore iron uptake system in highly virulent Yersinia (Yersinia pestis, Y. pseudotuberculosis, and Y. enterocolitica biotype 1B). Genes responsible for biosynthesis, transport, and regulation of the yersiniabactin (ybt) production are clustered on a mobile genetic element, the High-Pathogenicity Island (HPI) that is responsible for broad dissemination of the ybt genes in Enterobacteriaceae. However, the ybt gene cluster is absent from nearly half of Y. pseudotuberculosis O3 isolates and epidemic Y. pseudotuberculosis O1 isolates responsible for the Far East Scarlet-like Fever. Several potential siderophore-mediated iron uptake gene clusters are documented in Yersinia genomes, however, neither of them have been proven to be functional. It has been suggested that at least two siderophores alternative to Ybt may operate in the highly virulent Yersinia pestis/Y. pseudotuberculosis group, and are referred to as pseudochelin (Pch) and yersiniachelin (Ych). Furthermore, most sporadic Y. pseudotuberculosis O1 strains possess gene clusters encoding all three iron scavenging systems. Thus, the Ybt system appears not to be the sole endogenous siderophore iron uptake system in the highly virulent yersiniae and may be efficiently substituted and/or supplemented by alternative iron siderophore scavenging systems.

Adult intussusception caused by Yersinia enterocolitica enterocolitis.

Yersinia enterocolitica (YE) infection is a rare cause of intestinal intussusception, especially in adults. We herein, report a case of adult intussusception due to YE enterocolitis. A 24-year-old woman was admitted because of severe abdominal pain. She was clinically diagnosed with ileocolic intussusception on the basis of the findings of computed tomography (CT) and a gastrografin enema. Manual surgical reduction was sufficient to alleviate the intussusception. A histological examination of the lymph nodes around the ileocecum excluded lymphoma. Serological testing revealed that the cause of the intussusception was a YE infection. The patient's postoperative course was good and no recurrence was seen during the follow-up.