Local Bacterial Infection Research Articles

Acute Focal Bacterial Nephritis Associated With Reversible Splenial Corpus Callosum Lesion

Acute focal bacterial nephritis (AFBN) is a localized bacterial infection of the kidney, which presents as an inflammatory mass without formation of a frank abscess. Rare cases of AFBN are accompanied by neurological symptoms such as meningeal irritation, unconsciousness, and seizures. Clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) is characterized by transient high signal intensity splenial lesions on diffusion-weighted magnetic resonance imaging. MERS can be divided into two types: type 1 with an isolated splenium of the corpus callosum and type 2 with extensive white matter and/or entire callosal lesions. We experienced three rare cases of pediatric AFBN associated with neurological symptoms, including unconsciousness and reversible splenial corpus callosum lesion. The first case was an 8-year-old girl who had neurological symptoms, including unconsciousness, and AFBN was associated with MERS type 2. The second (5-year-old boy) and third (5-year-old girl) cases had neurological symptoms, including unconsciousness and AFBN with MERS type 1. Two of the three cases had AFBN caused by Escherichia coli . All three cases showed high levels of urinary beta 2 -microglobulin (B2MG). AFBN should be suspected in children with fever, rapid clinical deterioration, neurological symptoms including unconsciousness, and high urinary B2MG level. We recommend that abdominal enhanced computed tomography should be performed for the diagnosis of AFBN. Int J Clin Pediatr. 2020;9(3):82-86 doi: https://doi.org/10.14740/ijcp395

Elevated serum procalcitonin levels and their association with the prognosis of patients with liver cirrhosis.

Bacterial infection is a major complication in patients with liver cirrhosis. Procalcitonin is an early diagnostic marker of bacterial infection. This study aimed to investigate the association between the serum procalcitonin levels and the prognosis of patients with liver cirrhosis. We retrospectively analyzed the serum procalcitonin levels in 236 hospitalized patients with liver cirrhosis. The impact of the serum procalcitonin level on their prognoses was evaluated using multivariate Cox proportional hazards analyses and the Kaplan-Meier method. The serum procalcitonin level was higher (≥0.05 ng/mL) in 151 (64%) patients, and it was significantly higher in the patients with Child-Turcotte-Pugh class C than in those with Child-Turcotte-Pugh classes A/B. Patients with refractory ascites, hepatic encephalopathy, gastrointestinal bleeding, and bacterial infections had elevated serum procalcitonin levels. The multivariate analyses showed a serum procalcitonin level ≥0.05 ng/mL was an independent prognostic factor for liver cirrhosis (hazard ratio = 1.64; 95% confidence interval = 1.07-2.53; P = 0.024). During a median follow-up interval of 2.1 years, the three-year cumulative survival rates for the patients with normal and elevated serum procalcitonin levels were 72.9 and 56.0%, respectively (P < 0.001). The subgroup analyses that stratified the patients according to age, the Child-Turcotte-Pugh classification, and the presence of liver cancer showed the serum procalcitonin level was significantly associated with their prognoses. The patients with liver cirrhosis had higher serum procalcitonin levels, regardless of local bacterial infections, and higher procalcitonin levels were associated with poor prognoses.

Salivary Metabolomics Fingerprint of Chronic Apical Abscess with Sinus Tract: A Pilot Study.

Chronic apical abscess (CAA) is a lesion of apical periodontitis mostly characterized by areas of liquefactive necrosis with disintegrating polymorphonuclear neutrophils surrounded by macrophages. Its presence leads to local bacterial infection, systemic inflammatory response, pain, and swelling. The use of a novel approach for the study of CAA, such as metabolomics, seems to be important since it has proved to be a powerful tool for biomarkers discovery which could give novel molecular insight on CAA. So, the aim of this study was to verify the possibility to identify the metabolic fingerprint of CAA through the analysis of saliva samples. Nineteen patients were selected for this study: eleven patients affected by CAA with a sinus tract constituted the study group whereas eight patients without clinical and radiographic signs of CAA formed the healthy control group. Saliva samples were collected from each subject and immediately frozen at −80°C. Metabolomic profiles were obtained using a gas chromatography/mass spectrometry instrument. Subsequently, in order to compare the two groups, a multivariate statistical model was built that resulted to be statistically significant. The class of metabolites characterizing the CAA patients was closely related to the bacterial catabolism, tissue necrosis, and presence of a sinus tract. These preliminary results, for the first time, indicate that saliva samples analyzed by means of GC/MS metabolomics may be useful for identifying the presence of CAA, leading to new insights into this disease.

Toxoplasma gondii infection in two captive Patagonian maras

Toxoplasma gondii infection was diagnosed in 2 captive Patagonian maras (Dolichotis patagonum). One animal developed fatal systemic toxoplasmosis and had concurrent localized bacterial and fungal infections; its daughter remained clinically healthy. Microscopic findings included acute, coagulative necrosis, lymphohistiocytic inflammatory infiltrates, and extra- and intracellular parasites in the liver, myocardium, urinary bladder, and adrenal glands of the diseased animal. PCR and subsequent genotyping of parasites from fresh tissue from both cases revealed infection with T. gondii genotype II. Direct agglutination testing of blood from the healthy individual revealed high levels of T. gondii IgG antibodies. T. gondii is a potential cause of disease and lethality in captive and wild Patagonian maras, and toxoplasmosis should be considered when managing and providing veterinary care for this species.

Photodynamically Active Electrospun Fibers for Antibiotic-Free Infection Control.

Antimicrobial biomaterials are critical to aid in the regeneration of oral soft tissue and prevent or treat localized bacterial infections. With the rising trend in antibiotic resistance, there is a pressing clinical need for new antimicrobial chemistries and biomaterial design approaches enabling on-demand activation of antibiotic-free antimicrobial functionality following an infection that are environment-friendly, flexible and commercially viable. This study explores the feasibility of integrating a bioresorbable electrospun polymer scaffold with localized antimicrobial photodynamic therapy (aPDT) capability. To enable aPDT, we encapsulated a photosensitizer (PS) in polyester fibers in the PS inert state, so that the antibacterial function would be activated on-demand via a visible light source. Fibrous scaffolds were successfully electrospun from FDA-approved polyesters, either poly(ε-caprolactone (PCL) or poly[(rac-lactide)-co-glycolide] (PLGA), with encapsulated PS (either methylene blue (MB) or erythrosin B (ER)). These were prepared and characterized with regards to their loading efficiency (UV-vis spectroscopy), microarchitecture (SEM, porometry, and BET (Brunauer-Emmett-Teller) analysis), tensile properties, hydrolytic behavior (contact angle, dye release capability, degradability), and aPDT effect. The electrospun fibers achieved an ∼100 wt % loading efficiency of PS, which significantly increased their tensile modulus and reduced their average fiber diameter and pore size with respect to PS-free controls. In vitro, PS release varied between a burst release profile to limited release within 100 h, depending on the selected scaffold formulation, while PLGA scaffolds displayed significant macroscopic shrinkage and fiber merging, following incubation in phosphate buffered saline solution. Exposure of PS-encapsulated PCL fibers to visible light successfully led to at least a 1 log reduction in Escherichia coli viability after 60 min of light exposure, whereas PS-free electrospun controls did not inactive microbes. This study successfully demonstrates the significant potential of PS-encapsulated electrospun fibers as photodynamically active biomaterial for antibiotic-free infection control.

No Proof that Biofilm Bacteria are Causing Dermal Filler Granulomas

An estimated 1000 patients worldwide, who develop foreign body granulomas after the injection of all kinds of dermal fillers, are treated falsely with systemic antibiotics over several months – just because one pathologist claimed to have found the reason for granulomas in a local bacterial infection. The problem is the easiness today how authors can find, copy, and refer to articles, whose results they never questioned but cited, only. One copies the results from the other – and by the way of repeating a hypothesis several times, it becomes the truth for the majority of a whole community of dermatologists and aesthetic surgeons.

Treatment by untrained providers among sick infants in rural Odisha, India.

This study assessed the diagnosis, treatment and referral service provided by untrained providers for sick infants. In rural India, lack of trained providers causes inopportune treatment of sick infants and results in increase in child morbidity and mortality. The untrained providers deliver a significant proportion of health care for rural infants; however, there is a paucity of information on their treatment practice. A cross-sectional study was conducted in three rural blocks of Odisha. A total of 337 prescriptions recommended for sick infants were collected from the 15 untrained providers using pre-designed prescription form - designed as per the Integrated Management of Neonatal and Childhood Illness (IMNCI) guideline. The forms were collected through the periodic visit and regular follow-up to the providers. A total of 68% of infants were diagnosed with the possible serious bacterial infection, 56% fever, 10% feeding problems, 9% dysentery and 9% local bacterial infection. A total of 61% of sick infants prescribed antibiotics - cephalosporin was commonly prescribed (56%). Among severe persistent diarrhea-diagnosed infants, 76% prescribed oral rehydration salt (ORS), 48% zinc and 62% of them received various antibiotics. The untrained providers referred 23% of sick infants to trained providers/facilities. In rural settings, most of the sick infants sought care from untrained providers; however, none of them followed any standard treatment protocol. This study suggests there is a need for training on common disease algorithm and treatment using a standard guideline for untrained providers to reduce inopportuneness in the treatment of sick infants, promoting early diagnosis and referral services to public health systems.

Tissue Adaptations of Memory and Tissue-Resident Gamma Delta T Cells.

Epithelial and mucosal barriers are critical interfaces physically separating the body from the outside environment and are the tissues most exposed to microorganisms and potential inflammatory agents. The integrity of these tissues requires fine tuning of the local immune system to enable the efficient elimination of invasive pathogens while simultaneously preserving a beneficial relationship with commensal organisms and preventing autoimmunity. Although they only represent a small fraction of circulating and lymphoid T cells, γδ T cells form a substantial population at barrier sites and even outnumber conventional αβ T cells in some tissues. After their egress from the thymus, several γδ T cell subsets naturally establish residency in predetermined mucosal and epithelial locations, as exemplified by the restricted location of murine Vγ5+ and Vγ3Vδ1+ T cell subsets to the intestinal epithelium and epidermis, respectively. Because of their preferential location in barrier sites, γδ T cells are often directly or indirectly influenced by the microbiota or the pathogens that invade these sites. More recently, a growing body of studies have shown that γδ T cells form long-lived memory populations upon local inflammation or bacterial infection, some of which permanently populate the affected tissues after pathogen clearance or resolution of inflammation. Natural and induced resident γδ T cells have been implicated in many beneficial processes such as tissue homeostasis and pathogen control, but their presence may also exacerbate local inflammation under certain circumstances. Further understanding of the biology and role of these unconventional resident T cells in homeostasis and disease may shed light on potentially novel vaccines and therapies.

VIRULENCE AND ANTIBIOTIC RESISTANCE OF ISOLATES OF KLEBSIELLA PNEUMONIAE IN NEWBORNS WITH LOCALIZED AND GENERALIZED FORMS OF INFECTION

Objective.To study the effect of virulence and antibiotic sensitivity of K. pneumoniae on the course and outcome of localized and generalized forms of infection in newborns.The authors studied 25 samples of K. pneumoniae isolated from the blood (12 isolates) and feces (13 isolates) of the children with various forms of neonatal infection. Group 1 consisted of 12 children with bacteriologically proven neonatal sepsis, K. pneumoniae was isolated of their blood. Group 2 included 13 children with localized bacterial infection in the form of pneumonia, K. pneumoniae was isolated from their feces. The PCR method was used to determine the virulence factors of the isolates of K. pneumoniae-rmpA, aerobactin and colibactin. The sensitivity of K. pneumoniae to antibiotics was determined by the Kirby-Bauer method. The double disk method was used to determine the ability of K. pneumoniae to produce extended-spectrum β-lactamases (ESBL).Results.In Group 1 the isolates of K. pneumoniae produced ESBL in 8 children out of 12. The bacteria were sensitive to meropenem, amikacin and ciprofloxacin in 4 cases. One child demonstrated resistance to meropenem. The remaining 4 isolates were sensitive to the third-generation cephalosporins protected by aminopenicillins, amikacin, meropenem and ciprofloxacin. The rmpA gene was determined in the K. pneumoniae isolates in 6 children. The “string-test” of these colonies of K. pneumoniae in all cases gave a positive result. The genes of siderophores, aerobactin and colibactin were found in 3 isolates. Aerobactin and colibactin produced only rmpA-bearing strains. 3 isolates (23%) of K. pneumoniae produced ESBL in Group 2. In 8 out of 13 cases there was rmpA–gene and genes of aerobactin and colibactin in 11 and 7 cases accordingly. The “string-test” was positive in 8 cases, and there were only rmpA-positive bacteria. Siderophores were detected both in rmpA-positive and rmpA-negative isolates. The microbes produced BLBR and were rmpA-positive in 2 children. In one case, the isolates had neither the characteristic virulence factors, nor BLBR.Conclusion.The risk of developing localized and generalized forms of neonatal klebsiella infection is largely determined by microbiological features of the microorganism, its resistance and virulence. We observed clinical variants of the disease caused by K. pneumoniae, which simultaneously had two properties: high aggressiveness and resistance to antibiotic therapy.

Multifunctional magnetic ZnFe2O4-hydroxyapatite nanocomposite particles for local anti-cancer drug delivery and bacterial infection inhibition: An in vitro study

Abstract In this study, a co-precipitation method was applied to synthesize the ZnFe2O4 and ZnFe2O4 Hydrxoapatite (HAp) nanostructures. The microstructure and morphological characteristics of the nanoparticles were studied and well discussed. A dose-dependent biological evaluation comprising of their minimum inhibitory concentration (MIC) antibacterial features as well as their magnetic characteristics were analyzed. The results of vibrating-sample magnetometer (VSM) showed nanoscaled ZnFe2O4 HAp had lower saturation magnetization as well as higher coercive field than ZnFe2O4, which enables the ZnFe2O4 HAp nanoparticles to stimulate cell proliferation, differentiation and adhesion. A remarkable inhibitory effect of the nanoscaled ZnFe2O4 HAp was recognized on bacterial proliferation and growth in the optimal dose, 0.078 mg/L. Besides, a dose-dependent cytocompatibility tests of the nanoparticles on the HEK normal cell and G292 cancer cell was assessed by 3-(4,5-Dimethylthiazol-2-Yl)-2,5-Diphenyltetrazolium Bromide assay (MTT). All nanoparticles were cytocompatible and no cytotoxicity effect on normal and cancer cells was observed in the dose-dependent test. In addition, an in vitro test of the drug release from drug-loaded ZnFe2O4-HAp nanocarrier were investigated and well described. The Inhibitory effect of the drug-loaded ZnFe2O4-HAp nanoparticles was investigated in-vitro so that the nanoparticle possessed the ability for inhibiting cancer cell proliferation and growth. By the increment of the nanoparticles concentrations, G292 cancer cell proliferation was inhibited, while, HEK normal cell proliferation was stimulated. Conclusively for the first time, a robust composite based nanostructure as a promising material was developed for multiple applications of bone filler, drug delivery and cancer treatment.

Tonicity inversely modulates lipocalin-2 (Lcn2/24p3/NGAL) receptor (SLC22A17) and Lcn2 expression via Wnt/\u03b2-catenin signaling in renal inner medullary collecting duct cells: implications for cell fate and bacterial infection

BackgroundWe have previously evidenced apical expression of the 24p3/NGAL/lipocalin-2 receptor (Lcn2-R; SLC22A17) in inner medullary collecting duct (IMCD) cells, which are present in vivo in a hyperosmotic/-tonic environment that activates canonical Wnt/β-catenin signaling. The localization of Lcn2-R in the inner medulla is intriguing considering local bacterial infections trigger toll-like receptor-4 (TLR-4)-mediated secretion of the bacteriostatic Fe3+-free (apo-)Lcn2.AimTo determine the effects of osmolarity/tonicity changes, Wnt/β-catenin and TLR-4 activation on Lcn2-R and Lcn2 expression and cell viability in rat primary IMCD and mouse (m)IMCD3 cells.MethodsNormosmolarity/-tonicity was 300 mosmol/l whereas hyperosmolarity/-tonicity was induced by adding 100 mmol/l NaCl + 100 mmol/l urea (600 mosmol/l, 1-7 days). Lcn2-R and Lcn2 expression were determined by qPCR, immunoblotting, flow cytometry and immunofluorescence microscopy. β-catenin was silenced by RNAi. Cell viability/death was determined with MTT and LDH release assays. TLR-4 was activated by bacterial lipopolysaccharides (LPS).ResultsHyperosmotic/-tonic media upregulated Lcn2-R by ~4-fold and decreased Lcn2 expression/secretion, along with Wnt/β-catenin activation, in IMCD cells. These effects of hyperosmotic/-tonic media on Lcn2-R/Lcn2 expression were reverted by normosmolarity/-tonicity, β-catenin silencing and/or LPS. Exposure of cells with endogenous or stably overexpressing Lcn2-R to apo-Lcn2 or LPS decreased cell viability.ConclusionsLcn2-R upregulation and Lcn2 downregulation via Wnt/β-catenin may promote adaptive osmotolerant survival of IMCD cells in response to hyperosmolarity/-tonicity whereas Lcn2 upregulation and Lcn2-R downregulation via TLR-4 and/or normosmolarity/-tonicity may protect IMCD cells against bacterial infections and prevent autocrine death induction by Lcn2.

Role of Procalcitonin in Management of Infection in Solid Organ Transplantation Recipients: Review

Infections are a common cause of morbidity and mortality in solid organ transplantation (SOT) recipients. Procalcitonin (PCT) has garnered attention as an inflammatory marker that has been shown to be a valuable marker for early identification of systemic bacterial infection. However, interpretation of PCTs value in the different types of infections, transplanted organs, and post-operative courses can be challenging. We review the role of PCT in the management of infections in SOT recipients. First, the PCT level can be elevated immediately after transplant surgery, but those levels decline over one week and do not rise significantly unless an individual develops a systemic bacterial infection. Second, PCT is elevated in systemic bacterial infection, but not in localized bacterial infections or viral infection. Third, procalcitonin does not rise significantly during episodes of acute rejection, but it can be elevated with the use of antithymoglobulin for induction or rejection treatment. While issues remain with the use of PCT as a predictive, it may provide an important piece of information that guides clinical decision-making.

On The Stability Analysis of The General Mathematical Modeling of Bacterial Infection

In this study, a mathematical model examined the dynamics among populations of sensitive bacteria and resistant bacteria to antibiotic, antibiotic concentration and hosts immune system cells in an individual (or host), received antibiotic therapy in the case of a local bacterial infection, was proposed. Stability analysis of this model have been also performed. In addition that, results of the analysis have supported by numerical simulations.

Twice-daily red and blue light treatment for Candida albicans biofilm matrix development control.

Phototherapy has been proposed as a direct means of affecting local bacterial infections. However, the use of phototherapy to prevent fungal biofilm development has received comparatively less attention. This study aimed to determine the effects of red light treatment and blue light treatment, without a photosensitizer, on the development of Candida albicans biofilm. During the development of 48-h biofilms of C. albicans SN 425 (n = 10), the biofilms were exposed twice-daily to noncoherent blue and red light (LumaCare; 420nm and 635nm). The energy density applied was 72Jcm-2 for blue light and 43.8Jcm2, 87.6Jcm2, and 175.5Jcm2 for red light. Positive control (PC) and negative control (NC) groups were treated twice-daily for 1min with 0.12% chlorhexidine (CHX) and 0.89% NaCl respectively. Biofilms were analyzed for colony forming units (CFU), dry-weight, and exopolysaccharides (EPS-soluble and EPS-insoluble). Data was analyzed by one-way ANOVA and Tukey post hoc test (α = 0.05). Dry-weight was lower than NC (p < 0.001) and approached PC levels with both red and blue light treatments. CFU were also lower in groups exposed to blue light and higher durations of red light (p < 0.05). EPS-soluble and EPS-insoluble measures were variably reduced by these light exposures. In conclusion, twice-daily exposure to both blue and red lights affect the biofilm development and physiology of polysaccharide production and are potential mechanisms for the control of C. albicans biofilm matrix development.

Epidermal Electronic Systems for Measuring the Thermal Properties of Human Skin at Depths of up to Several Millimeters

AbstractMonitoring the composition, blood flow properties, and hydration status of human skin can be important in diagnosing disease and tracking overall health. Current methods are largely limited to clinical environments, and they primarily measure properties of superficial layers of the skin, such as the stratum corneum (10–40 µm). This work introduces soft, skin‐like thermal depth sensors (e‐TDS) in designs that seamlessly couple with human skin and measure its thermal properties with depth sensitivity that can extend up to 6 mm beneath the surface. Guidelines for tailoring devices to enable measurements through different effective depths follow from a systematic set of experiments, supported by theoretical modeling. On‐body testing validates the physiological relevance of measurements using the e‐TDS platform, with potential to aid the diagnosis of deep cutaneous and systemic diseases. Specific demonstrations include measurements that capture responses ranging from superficial changes in skin properties that result from application of a moisturizer, to changes in microvascular flow at intermediate depths induced by heating/cooling, to detection of inflammation in the deep dermis and subcutaneous fat in an incidence of a local bacterial infection, cellulitis.

Both localized and systemic bacterial infections are predicted by injection drug use: A prospective follow-up study in Swedish criminal justice clients.

BackgroundBoth skin and soft tissue infections (SSTI) and systemic bacterial infections are common in people who inject drugs (PWID), but data on incidence and risk factors are lacking. We compared registered diagnoses for such infections in Swedish criminal justice clients with regard to injecting drug use.MethodsBaseline interview data from the Swedish Prison and Probation Service on drug use in PWID and non-PWID with problematic alcohol use were linked to follow-up data from national Swedish registers on hospital diagnoses and/or death. Associations between drug use and later diagnosis of SSTI and systemic bacterial infection (septicemia or bacterial infection of the heart, bone/joints or central nervous system) were analyzed by Cox regression.ResultsIncidence rates of SSTI was 28.3 per 1,000 person-years for PWID (n = 2,444) and 10.0 for non-PWID with problematic alcohol use (n = 735). Incidence rates of systemic bacterial infection was 9.1 per 1,000 person-years for PWID and 2.7 per 1,000 person-years for non-PWID. Injection drug use was associated with a significantly increased risk of bacterial infections, for main drugs heroin (SSTI: Hazard ratio [HR] 2.45; systemic infection: HR 2.75), amphetamine (SSTI: HR 1.60; systemic infection: HR 2.19), and polysubstance use (SSTI: HR 1.92; systemic infection: HR 2.01). In relation to injection use of amphetamine and polysubstance use, PWID mainly using heroin had higher risk of SSTI.ConclusionsInjection drug use predicted both SSTI and systemic bacterial infection, with a particularly high risk of SSTI in PWID mainly using heroin. The results imply the need for increased attention to bacterial infections among PWID, in terms of clinical management, prevention and research.

Hepatocytes and neutrophils cooperatively suppress bacterial infection by differentially regulating lipocalin-2 and neutrophil extracellular traps.

Both hepatocytes and neutrophils combat bacterial infection through the production of LCN2; extracellular LCN2 secreted by hepatocytes limits systemic bacterial infection, whereas neutrophils carry LCN2 protein to the local site and against local bacterial infection through NETs. (Hepatology 2018).

Value of procalcitonin for diagnosing perioperative pneumonia, urinary infections and superficial surgical site infections in patients undergoing primary hip and knee arthroplasty.

Serum procalcitonin (PCT) levels may be helpful for the diagnosis of infections during the perioperative period of arthroplasty. However, there is much debate in the literature regarding the appropriate cut-off value for different types of surgery and local bacterial infection. The present study aimed to evaluate serum PCT levels in patients undergoing arthroplasty and to determine the cut-off value that may represent perioperative pneumonia, urinary infections and superficial surgical site infections. The present retrospective study included a total of 500 patients treated between July 2014 and August 2015. The case group contained 25 patients with perioperative infections (pneumonia, urinary and superficial surgical site infections), and the control group contained 25 patients without any post-surgical complications. Serum levels of PCT and white blood cells (WBC) were measured pre-operatively (D0) and at post-operative D4, D6 and D8, and the sensitivity, specificity and predictive value of these parameters were assessed. Regarding the comparison of the mean PCT levels between the case and the control group, a significant difference was seen at D8 (P=0.007), while no significant differences were observed at D0 (P=0.010), D4 (P=0.069) and D6 (P=0.093). No statistically significant differences in WBC levels between groups were observed for (P>0.01). In the control group, the PCT levels at D4 (0.062±0.020 ng/ml) were 2-fold of the mean baseline value, followed by a decrease until D6 (0.051±0.019 ng/ml) and a return close to the normal range by D8 (0.032±0.015 ng/ml). The PCT levels in the case group had rapidly increased on D4 (0.510±1.208 ng/ml). In contrast to the control group, they continuously increased on D6 (0.527±1.360 ng/ml) and D8 (0.686±1.117 ng/ml). From a clinical point of view, infection events were indicated in these patients during post-operative follow-up. For PCT, the area under the receiver operating characteristic curve (AUC) was 0.978 [95% confidence interval (CI), 0.933-1.022], and for WBC, the AUC was 0.562 (95% CI, 0.398-0.0.726). Based on the above data, the PCT value was a significant predictor of infection (AUC>0.9). For PCT, the cut-off point of 0.0995 ng/ml was associated with a sensitivity of 96% and a specificity of 100%. However, WBC were not a significant predictor of infection (0.5<AUC<0.7), and the cut-off value of 7.05×109/l was associated with a sensitivity of 64% and a specificity of 44%. In conclusion PCT was found to be a promising marker for diagnosing bacterial infections post-arthroplasty due to its high specificity. Based on the sensitivity and the specificity, detecting PCT may be more valuable than using WBC in the diagnosis of sepsis-associated pathological changes in the perioperative period.

A Nanocomposite Hydrogel with Potent and Broad-Spectrum Antibacterial Activity.

Local bacterial infection is a challenging task and still remains a serious threat to human health in clinics. Systemic administration of antibiotics has only short-term antibacterial activity and usually causes adverse effects and bacterial resistance. A bioadhesive hydrogel with broad-spectrum and on-demand antibiotic activity is highly desirable. Here, we designed a pH-responsive nanocomposite hydrogel via a Schiff base linkage between oxidized polysaccharides and cationic dendrimers encapsulated with silver nanoparticles. The antibacterial components, both the cationic dendrimers and silver species, could be released in response to the acidity generated by growing bacteria. The released cationic polymer and silver exhibited a synergistic effect in antibacterial activity, and thus, the nanocomposite hydrogel showed potent antibacterial activity against both Gram-negative ( Escherichia coli and Pseudomonas aeruginosa) and Gram-positive bacteria ( Staphylococcus epidermidis and Staphylococcus aureus). The gel showed superior in vivo antibacterial efficacy against S. aureus infection compared with a commercial silver hydrogel at the same silver concentration. In addition, no obvious hemolytic toxicity, cytotoxicity, and tissue and biochemical toxicity were observed for the antibacterial hydrogel after incubation with cells or implantation. This study provides a facile and promising strategy to develop smart hydrogels to treat local bacterial infections.

Investigations of Peptide-Based Biocompatible Injectable Shape-Memory Hydrogels: Differential Biological Effects on Bacterial and Human Blood Cells.

Here, we report the self-assembly of Amoc (9-anthracenemethoxycarbonyl)-capped dipeptides, which self-assemble to form injectable, self-healable, and shape-memory hydrogels with inherent antibacterial properties. Amoc-capped dipeptides self-assemble to form nanofibrillar networks, which are established by several spectroscopic and microscopic techniques. The inherent antibacterial properties of hydrogels are evaluated using two Gram-positive Staphylococcus aureus, Bacillus subtilis and three Gram-negative Escherichia coli, Pseudomonas aeruginosa, and Salmonella typhi bacteria. These hydrogels exhibit potent antibacterial efficacy against Gram-positive and Gram-negative bacteria. The minimum inhibitory concentrations (MIC50) for the hydrogels on Gram-positive bacteria are in the range of 10-200 μM hydrogelator concentrations. The biocompatibility and cytotoxicity of the hydrogels are evaluated using 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), hemolysis, and lipid peroxidation (LPO) assay on human blood cells. The hydrogels are hemocompatible and they decrease LPO values on human red blood cells probably via increased cellular stability against oxidative stress. Furthermore, MTT data show that the hydrogels are biocompatible and promote cell viability and proliferation on cultured human white blood cells. Taken together, these results may suggest that our designed injectable hydrogels could be useful to prevent localized bacterial infections.