Development Of Bacterial Infections Research Articles

The Balance between Protealysin and Its Substrate, the Outer Membrane Protein OmpX, Regulates Serratia proteamaculans Invasion.

Serratia are opportunistic bacteria, causing infections in plants, insects, animals and humans under certain conditions. The development of bacterial infection in the human body involves several stages of host-pathogen interaction, including entry into non-phagocytic cells to evade host immune cells. The facultative pathogen Serratia proteamaculans is capable of penetrating eukaryotic cells. These bacteria synthesize an actin-specific metalloprotease named protealysin. After transformation with a plasmid carrying the protealysin gene, noninvasive E. coli penetrate eukaryotic cells. This suggests that protealysin may play a key role in S. proteamaculans invasion. This review addresses the mechanisms underlying protealysin's involvement in bacterial invasion, highlighting the main findings as follows. Protealysin can be delivered into the eukaryotic cell by the type VI secretion system and/or by bacterial outer membrane vesicles. By cleaving actin in the host cell, protealysin can mediate the reversible actin rearrangements required for bacterial invasion. However, inactivation of the protealysin gene leads to an increase, rather than decrease, in the intensity of S. proteamaculans invasion. This indicates the presence of virulence factors among bacterial protealysin substrates. Indeed, protealysin cleaves the virulence factors, including the bacterial surface protein OmpX. OmpX increases the expression of the EGFR and β1 integrin, which are involved in S. proteamaculans invasion. It has been shown that an increase in the invasion of genetically modified S. proteamaculans may be the result of the accumulation of full-length OmpX on the bacterial surface, which is not cleaved by protealysin. Thus, the intensity of the S. proteamaculans invasion is determined by the balance between the active protealysin and its substrate OmpX.

Dysbiosis by Eradication of Helicobacter pylori Infection Associated with Follicular Gastropathy and Pangastropathy.

Dysbiosis plays an important role in the development of bacterial infections in the gastric mucosa, particularly Helicobacter pylori. The international guidelines for the treatment of H. pylori infections suggest standard triple therapy (STT). Nevertheless, because of the increasing resistance rates to clarithromycin, metronidazole has been widely considered in several countries. Unfortunately, the non-justified administration of antibiotics induces dysbiosis in the target organ. We characterized the gastric microbiota of patients diagnosed with follicular gastropathy and pangastropathy attributed to H. pylori infection, before and after the administration of STT with metronidazole. Dominant relative abundances of Cutibacterium were observed in pre-treatment patients, whereas H. pylori was observed at <11%, suggesting the multifactor property of the disease. The correlation of Cutibacterium acnes and H. pylori with gastric infectious diseases was also evaluated using quantitative real-time polymerase chain reaction. The dominance of C. acnes over H. pylori was observed in gastritis, gastropathies, and non-significant histological alterations. None of the microorganisms were detected in the intestinal metaplasia. Post-treatment alterations revealed an increase in the relative abundances of Staphylococcus, Pseudomonas, and Klebsiella. Non-H. pylori gastrointestinal bacteria can be associated with the initiation and development of gastric diseases, such as pathobiont C. acnes.

Extracellular Prdx1 mediates bacterial infection and inflammatory bone diseases

AimWe aimed to determine the role of extracellular peroxiredoxin 1 (Prdx1) in the pathogenesis of bacterial infections and inflammatory bone disease. Materials and methodsWe first investigated the role of Prdx1 using knockout mice. Next, we determined the role of extracellular Prdx1 in bacterial infections by using a neutralizing antibody against Prdx1. We finally investigated whether blockade of extracellular Prdx1 affected high- or low-grade inflammatory bone diseases using calvarial osteolysis, collagen-induced arthritis (CIA), and microgravity-induced bone loss in mouse models. Key findingsThe lack of Prdx1 increased susceptibility to infections by Listeria monocytogenes or Escherichia coli. Prdx1 is released into the serum upon E. coli infection, and blockade of extracellular Prdx1 confers significant protection against bacterial infections. Our data suggested that circulating Prdx1 is increased by the development of osteolytic disease, and that blockade of extracellular Prdx1 exerts therapeutic effects against high- and low-grade inflammatory bone loss. In addition, the release of Prdx1 under inflammatory osteolytic conditions partly depends on non-canonical TIR-domain-containing adapter-inducing interferon-β (TRIF)-caspase-11-gasdemin D (GSDMD) inflammasome pathways. SignificanceExtracellular Prdx1 is involved in the development of bacterial infections and inflammatory bone disease. Thus, extracellular Prdx1 may represent a novel therapeutic target for bacterial infections or inflammatory osteolytic diseases.

Effect of subinhibitory doses of rifaximin on in vitro Pseudomonas aeruginosa adherence and biofilm formation to biotic and abiotic surface models.

The adhesion of Pseudomonas aeruginosa to biotic and abiotic surfaces is responsible for the persistence and development of bacterial infection. To fill the gap in the knowledge regarding the relationship between rifaximin susceptibility and biofilm formation, and to investigate the effect of subinhibitory doses of rifaximin on the adhesion and biofilm formation. A total of 10 isolates of P. aeruginosa were obtained from 110 urine samples of urinary tract infection (UTI) patients. Biofilm formation on polystyrene microtiter plates, minimum inhibitory concentrations (MICs) of rifaximin against the 10 isolates of P. aeruginosa (Pa1-Pa10), the effect of sub-MICs of rifaximin (0.5 × MIC, 0.25 × MIC, 0.125 × MIC, and 0.06 × MIC) on biofilm formation by the Pa4 isolate to polystyrene microtiter plates, and the adhesion to human epithelial cells (HECs) in vitro were evaluated. The MICs of rifaximin against 10 isolates ranged from 62.5 μg/mL to 1000 μg/mL. The Pa4 isolate produced the highest level of biofilm formation, while the MIC of Pa4 was 125 μg/mL. There was no correlation between bacterial susceptibility to rifaximin and biofilm formation (r: -0.016; p > 0.05). Sub-MIC doses of rifaximin significantly reduced the biofilm formation on abiotic surfaces, while only 0.5 × MIC, 0.25 × MIC and 0.12 × MIC of rifaximin reduced the adhesion to HECs significantly (p < 0.05) in a dose-dependent manner. This pioneering study demonstrated the negative effect of sub-MIC doses of rifaximin on biofilm formation and adhesion to abiotic and biotic surfaces in vitro.

Angiogenic Modification of Microfibrous Polycaprolactone by pCMV-VEGF165 Plasmid Promotes Local Vascular Growth after Implantation in Rats.

Insufficient vascular growth in the area of artificial-material implantation contributes to ischemia, fibrosis, the development of bacterial infections, and tissue necrosis around the graft. The purpose of this study was to evaluate angiogenesis after implantation of polycaprolactone microfiber scaffolds modified by a pCMV-VEGF165-plasmid in rats. Influence of vascularization on scaffold degradation was also examined. We investigated flat microfibrous scaffolds obtained by electrospinning polycaprolactone with incorporation of the pCMV-VEGF-165 plasmid into the microfibers at concentrations of 0.005 ng of plasmid per 1 mg of polycaprolactone (0.005 ng/mg) (LCGroup) and 0.05 ng/mg (HCGroup). The samples were subcutaneously implanted in the interscapular area of rats. On days 7, 16, 33, 46, and 64, the scaffolds were removed, and a histological study with a morphometric evaluation of the density and diameter of the vessels and microfiber diameter was performed. The number of vessels was increased in all groups, as well as the resorption of the scaffold. On day 33, the vascular density in the HCGroup was 42% higher compared to the control group (p = 0.0344). The dose-dependent effect of the pCMV-VEGF165-plasmid was confirmed by enhanced angiogenesis in the HCGroup compared to the LCGroup on day 33 (p-value = 0.0259). We did not find a statistically significant correlation between scaffold degradation rate and vessel growth (the Pearson correlation coefficient was ρ = 0.20, p-value = 0.6134). Functionalization of polycaprolactone by incorporation of the pCMV-VEGF165 plasmid provided improved vascularization within 33 days after implantation, however, vessel growth did not seem to correlate with scaffold degradation rate.

1773. Evaluation of Fluoroquinolone Prophylaxis in Preventing Bacterial Infection in Neutropenic Afebrile Patients Without Leukemias or HSCT: A Systematic Review

Abstract Background Per 2010 Infectious Diseases Society of America (IDSA) Clinical Practice Guideline for the Use of Antimicrobial Agents in Neutropenic Patients with Cancer, routine use of fluoroquinolone (FQ) chemoprophylaxis in low-risk populations (defined as those with solid tumors or lymphoma undergoing chemotherapy) is not recommended to prevent febrile neutropenic episodes as it was not found to impact all-cause mortality. Since these guidelines were published, there have been additional randomized trials (RCTs) of FQ chemoprophylaxis in patients with cancer. Our objective was to assess the efficacy of FQ vs placebo in preventing probable or confirmed bacterial infection in patients with cancer who did not have leukemias or hematopoietic stem cell transplant (HSCT). Secondary outcomes of interest included febrile episodes, mortality, and adverse effects of antibiotic use. Methods Medline via PubMed, The Cochrane Central Register of Controlled Trials, and SCOPUS from inception through 2/17/2022 were searched. We included RCTs in English comparing FQ to placebo in preventing neutropenic fever and bacterial infections in patients with cancer who did not have leukemias or HSCT. Results We included 5 RCTs (N= 3158). The rates of probable or confirmed bacterial infection in patients with cancer revealed 541/1562 (34.6%) infections in the FQ group and 679/1560 (43.5%) in the placebo group (OR: 0.68, 95% CI:0.59,0.79, I2 = 57%, p=0.002). In evaluating development of febrile episodes, 300/1566 (19.2%) events were noted in the FQ group and 407/1555 (26.2%) in the placebo group (OR: 0.58, 95% CI:0.41,0.83, I2 = 0%, p&amp;lt; 0.001). Mortality events in the FQ group were 113/1597(7.1%) and 124/1508 (8.2%) in the placebo group (OR: 0.76, 95% CI:0.53,1.1, I2 = 7%, p=0.15). Adverse events associated with antibiotic use in the studies were more frequent in the FQ group. Figure 1Forest Plot of Mortality in included studiesFigure 2Results on Development of Fevers in included studies.Figure 3Forest plot of Probable or Proven Infection in included studies. Conclusion Although evidence does not show that FQ prophylaxis provides mortality benefit, it did show a decrease in development of bacterial infections and febrile episodes. This suggests that treatment may still provide clinical benefit to this population of patients, but must be weighed against risks and consequences of long-term antibiotic use, which were not reported by the included studies. Disclosures All Authors: No reported disclosures.

Global hemostatic profiling in patients with decompensated cirrhosis and bacterial infections

Background & AimsBacterial infections in cirrhosis are associated with increased bleeding risk. To assess the factors responsible for bleeding tendency in patients with bacterial infections, we conducted a prospective study comparing all 3 aspects of hemostasis (platelets, coagulation, and fibrinolysis) in hospitalized patients with decompensated cirrhosis with vs. without bacterial infections.MethodsPrimary hemostasis assessment included whole blood platelet aggregation and von Willebrand factor (VWF). Coagulation assessment included procoagulant factors (fibrinogen, factor II, V, VII, VIII, IX, X, XI, XII, XIII), natural anticoagulants (protein C, protein S, antithrombin) and thrombomodulin-modified thrombin generation test. Fibrinolysis assessment included fibrinolytic factors (plasminogen, t-PA, PAI-1, α2-AP, TAFIa/ai) and plasmin-antiplasmin complex (PAP).ResultsEighty patients with decompensated cirrhosis were included (40 with and 40 without bacterial infections). Severity of cirrhosis and platelet count were comparable between groups. At baseline, patients with cirrhosis and bacterial infections had significantly lower whole blood platelet aggregation, without significant differences in VWF. Regarding coagulation, bacterial infections were associated with reduced procoagulant factors VII and XII, and a significant reduction of all natural anticoagulants. However, thrombomodulin-modified thrombin generation was comparable between the study groups. Finally, although mixed potentially hypo-fibrinolytic (lower plasminogen) and hyper-fibrinolytic (higher t-PA) changes were present in bacterial infections, a comparable level of PAP was detected in both groups. Upon resolution of infection (n = 29/40), platelet aggregation further deteriorated whereas coagulation and fibrinolysis factors returned to levels observed in patients without bacterial infections.ConclusionIn hospitalized patients with decompensated cirrhosis, bacterial infections are associated with reduced whole blood platelet aggregation and a significant decrease of all natural anticoagulants, which may unbalance hemostasis and potentially increase the risk of both bleeding and thrombosis.Lay summaryBacterial infections are a common issue in hospitalized patients with decompensated cirrhosis (i.e. patients hospitalized due to severe complications of advanced chronic liver disease). Patients with decompensated cirrhosis who acquire infections may be at increased risk of bleeding complications following invasive procedures (that is a procedure in which the body is penetrated or entered, for instance by a needle or a tube). As bleeding complications in decompensated cirrhosis are associated with a high risk of further decompensation and death, there is an urgent need to understand the factors responsible for such increased bleeding tendency. Herein, we investigated the alterations of hemostasis (that is the physiological process responsible for clot formation and stability) in patients with decompensated cirrhosis and bacterial infections. We found that development of bacterial infections in these patients is associated with alterations of hemostasis (particularly of platelets and clotting cascade) that may increase the risk of both bleeding and thrombotic complications.

Patients With Acute-on-Chronic Liver Failure Have Greater Healthcare Resource Utilization After Liver Transplantation

Although liver transplantation (LT) has been demonstrated to provide survival benefit for patients with acute-on-chronic liver failure (ACLF), data are lacking regarding resource utilization for this population after LT. We retrospectively reviewed data from 10 centers in North America of patients transplanted between 2018 and 2019. ACLF was identified by using the European Association for the Study of the Liver-Chronic Liver Failure criteria. We studied 318 patients of whom 106 patients (33.3%) had no ACLF, 61 (19.1%) had ACLF-1, 74 (23.2%) had ACLF-2, and 77 (24.2%) had ACLF-3 at transplantation. Healthcare resource utilization after LT was greater among recipients with ACLF compared with patients without ACLF regarding median post-LT length of hospital stay (LOS) (P < .001), length of post-LT dialysis (P < .001), discharge to a rehabilitation center (P < .001), and 30-day readmission rates (P= .042). Multivariable negative binomial regression analysis demonstrated a significantly longer LOS for patients with ACLF-1 (1.9 days; 95% confidence interval [CI], 0.82-7.51), ACLF-2 (6.7 days; 95% CI, 2.5-24.3), and ACLF-3 (19.3 days; 95% CI, 1.2-39.7), compared with recipients without ACLF. Presence of ACLF-3 at LT was also associated with longer length of dialysis after LT (9.7 days; 95% CI, 4.6-48.8) relative to lower grades. Multivariable logistic regression analysis revealed greater likelihood of discharge to a rehabilitation center among recipients with ACLF-1 (odds ratio [OR], 1.79; 95% CI, 1.09-4.54), ACLF-2 (OR, 2.23; 95% CI, 1.12-5.01), and ACLF-3 (OR, 2.23; 95% CI, 1.40-5.73). Development of bacterial infection after LT also predicted LOS (20.9 days; 95% CI, 6.1-38.5) and 30-day readmissions (OR, 1.39; 95% CI, 1.17-2.25). Patients with ACLF at LT, particularly ACLF-3, have greater post-transplant healthcare resource utilization.

Multidrug-Resistant Infections and Outcome of Critically Ill Patients with Coronavirus Disease 2019: A Single Center Experience.

Background: The aim of this study was to assess the drivers of multidrug-resistant (MDR) bacterial infection development in coronavirus disease 2019 (COVID-19) and its impact on patient outcome. Methods: Retrospective analysis on data from 32 consecutive patients with COVID-19, admitted to our intensive care unit (ICU) from March to May 2020. Outcomes considered were MDR infection and ICU mortality. Results: Fifty percent of patients developed an MDR infection during ICU stay after a median time of 8 [4-11] days. Most common MDR pathogens were carbapenem-resistant Klebsiella pneumoniae and Acinetobacter baumannii, causing bloodstream infections and pneumonia. MDR infections were linked to a higher length of ICU stay (p = 0.002), steroid therapy (p = 0.011), and associated with a lower ICU mortality (odds ratio: 0.439, 95% confidence interval: 0.251-0.763; p < 0.001). Low-dose aspirin intake was associated with both MDR infection (p = 0.043) and survival (p = 0.015). Among MDR patients, mortality was related with piperacillin-tazobactam use (p = 0.035) and an earlier onset of MDR infection (p = 0.042). Conclusions: MDR infections were a common complication in critically ill COVID-19 patients at our center. MDR risk was higher among those dwelling longer in the ICU and receiving steroids. However, MDR infections were not associated with a worse outcome.

Experimental justification of the efficacy of Zn and Ag citrates in bird bacterioses

Experimental justification of the efficacy of Zn and Ag citrates in bird bacterioses

The Grafting of Multifunctional Antithrombogenic Chemical Networks on Polyurethane Intravascular Catheters.

Intravascular catheters (IVCs) and other medical tubing are commonly made of polymeric materials such as polyurethane (PU). Polymers tend to be fouled by surface absorption of proteins and platelets, often resulting in the development of bacterial infections and thrombosis during catheterization, which can lead to embolism and death. Existing solutions to fouling are based on coating the IVCs with hydrophilic, anti-thrombogenic, or antimicrobial materials. However, the delamination of the coatings themselves is associated with significant morbidity, as reported by the United States Food and Drug Administration (FDA). We developed a lubricious, antimicrobial, and antithrombogenic coating complex, which can be covalently attached to the surface of industrial PU catheters. The coating complex is pre-synthesized and comprises 2-methacryloyloxyethyl phosphorylcholine (MPC) as an antifouling agent, covalently attached to branched polyethyleneimine (bPEI) as a lubricating agent. The two-step coating procedure involves PU-amine surface activation using a diisocyanate, followed by chemical grafting of the bPEI-S-MPC complex. Compared with neat PU, the coating was found to reduce the coefficient of friction of the IVC surface by 30% and the hemolysis ratio by more than 50%. Moreover, the coating exhibited a significant antimicrobial activity under JIS Z2801:2000 standard compared with neat PU. Finally, in in-vivo acute rabbit model studies, the coating exhibited significant antithrombogenic properties, reducing the thrombogenic potential to a score of 1.3 on coated surfaces compared with 3.3 on uncoated surfaces. The materials and process developed could confer lubricious, antithrombogenic, and antimicrobial properties on pre-existing PU-based catheters.

БАКТЕРИАЛЬНАЯ ТРАНСЛОКАЦИЯ В ПАТОГЕНЕЗЕ ОСЛОЖНЕНИЙ ЦИРРОЗА ПЕЧЕНИ

Background. Understanding of intestinal bacteria-host interaction physiology as well as bacterial translocation characteristics at the initial stages and in advanced cirrhosis emphasizes the importance of approaches minimizing the migration of microorganisms and their components from the intestinal lumen. Objective – to provide a brief review of publications highlighting the problem of bacterial intestinal translocation as the main mechanism for the development of bacterial infections and pro-inflammatory status in patients with liver cirrhosis. Material and methods. We performed the study and analysis of English- and Russian-language articles over the past 30 years contained in the following databases: PubMed, Cochrane Collaboration, UpToDate. The key words were: «intestinal microflora translocation», «bacterial translocation», «translocation markers». Results. Contemporary views on changes of the intestinal barrier and those of innate and adaptive immunity systems in liver diseases are considered. Data on possibility and signifcance of detecting bacterial translocation are presented.Current methods used for gut microbiome analysis as well as some areas for future research are discussed. Conclusion. A validated marker/markers is required to study bacterial translocation in cirrhosis.

Plasma Thrombomodulin Levels are Associated with Endothelial Injury in Patients with Bacterial Infections.

Endothelial injury is the key to the occurrence and development of bacterial infections. The aim of this study was to discuss the relationship between the molecular marker of endothelial damage, thrombomodulin (TM), and infectious disease severity, and prognosis. From January 2017 to April 2018, 296 patients with bacterial infections and 163 controls were recruited from our hospital. The concentrations of thrombomodulin and other routine coagulation and inflammatory factors were quantified. Plasma levels of thrombomodulin were obviously increased in infection group compared with control group (8.30 (7.23 - 9.68) vs. 15.83 (10.60 - 22.20) TU/mL, p < 0.001) and logistic regression analysis showed that the thrombomodulin was an independent risk factor for bacterial infection (OR, 1.189 (1.079 - 1.311)). In the infection group, patients with elevated thrombomodulin levels (> 75th percentile of its distribution, n = 71) experienced a higher level of coagulation factors (p < 0.05) and inflammatory factors (p < 0.05) than patients with levels below this cutoff. Multiple linear regression analysis showed that there was a positive correlation among the plasma thrombomodulin and D-dimer, white blood cells, and procalcitonin (β coefficient = 0.590, 0.220, and 0.208, p = 0.004, 0.027, and 0.025, respectively). With the increase of severity of disease, thrombomodulin levels gradually rose (13.58 ± 0.47 TU/mL vs. 25.07 ± 2.01 TU/mL vs. 31.34 ± 2.56 TU/mL, respectively, p < 0.001). Furthermore, there was an abnormal increase of plasma thrombomodulin in patients with bacterial infections and poor prognosis (p < 0.05). The area under curve of thrombomodulin as diagnosis for organ failure and non-survivor was 0.867 and 0.778, respectively. Plasmatic level of thrombomodulin could be considered as a diagnostic tool for bacterial infections. An increase in thrombomodulin plasmatic level was associated with poor outcome.

THE FUNCTIONAL ACTIVITY OF INNATE IMMUNITY CELLS IN BACTERIAL INFECTION ON BACKGROUND OF THERMAL STRESS

Maintenance of thermo homeostasis under the coordinating influence of the hypothalamus is ensured by integrative interaction of various systems organisme, including the immune system. Temperature stress in infectious diseases activates the reaction of heat shock, the biochemical consequence of which is the initiation of the organism’s defense against the pathogen. Cells of innate immunity (neutrophils and macrophages) are the first line of protection against pathogenic agents and play a primary role in the development of bacterial infections. Of particular interest is the study of the duration of the effect of hyperthermia to achieve a balance between the bioenergetic costs of these cells, as well as the study of the course of the pathological process in an organism previously exposed to hige temperature. The functional status of neutrophils and macrophages, including phagocytosis, the activity of enzymes of the oxygen-dependent system: lactate dehydrogenase, cytochrome oxidase, myeloperoxidase, cellular stimulation (intracellular AMPase content) and the content of nitrogen oxide metabolites have been studied in the model of animals exposed to low and high temperatures. It has been established that under hyperthermia conditions, the change in the functional activity of cells by enzyme level is more pronounced than when exposed to animals with low temperature, especially 4 h exposure. In animals pre-exposed to heat stress, manifestations of pseudotuberculosis infection were more severe with an increase in mortality rates by 2.6 times, compared to animals infected by bacteria. These animals had a high stimulation of effector cells of inflammation in the initial periods (at 7 days) their metabolism was enhanced, which was expressed of the activity of enzymes of the oxygen-dependent system, as well as in high nitroxide-producing activity. In target organs (lung, liver, spleen) of experienced animals the severe disturbance of blood circulation in combination with significant destructive changes typical for generalized infection were showed. At dead animals on the background of marked hemorrhagic component pathological process and weak cell inflammatory response observed depletion of the immune system (delimphatization), indicating a decrease in defense reactions and the development of immunodeficiency. Thus, under conditions of heat stress (+30°С), the intensity of the reaction of innate immunity cells in terms of enzyme’s functional activity was higher than when exposed to animals of low temperature (+4°C). Under these temperature conditions, a high level of cell priming was determined, which reduced their killing potential. These data indicate the adequacy of the model used to reproduce induced secondary immunodeficiency in a congenital defense system. Moreover, in the pathogenesis of pseudotuberculosis infection against the background of prolonged action high temperature, the effects of phagocytes oxidative stress in the structural changes of immunocompetent organs were detected.

English

This study aimed to investigate the incidence of bacterial infection in chronic hepatitis C virus (HCV) patients with cirrhosis and association between toll-like receptor 4 D299G gene polymorphism and Gram-negative bacterial infections in the patients. 100 HCV cirrhotic patients with ascites and 20 age- and sex-matched healthy subjects as control were included. Conventional culture methods were used to identify the causative organism of infection. Toll-like receptor 4 D299G polymorphism was detected by PCR- RFLP (polymerase chain reaction &ndash; restriction fragment length polymorphism). Patients were divided into: Group I: 100 HCV cirrhotic patients with ascites. They were subdivided into: Group I (a): Patients with Toll-like receptor 4 D299G polymorphism, Group I (b): Patients without polymorphism. Group II (control): 20 healthy subjects. This study showed significant higher incidence of infections in cirrhotic patients with Toll-like receptor 4 D299G polymorphism which play a role in the development of bacterial infection in cirrhotic patients that makes down-regulation of TLR4 response one of the immune mechanisms predisposed to Gram negative bacterial infection in cirrhotic patients. &nbsp; Key words: TLR-4 gene polymorphism, cirrhosis, bacterial infection.&nbsp

PROTON PUMP INHIBITORS INCREASE THE OVERALL RISK OF DEVELOPING BACTERIAL INFECTIONS IN PATIENTS WITH CIRRHOSIS.

Acid suppression has been associated with adverse events; such as, enteric infections. Proton pump inhibitors (PPI) are frequently prescribed in patients with cirrhosis, but is unclear if PPI are associated with the development of bacterial infections in these patients. To assess the impact of PPI intake on the development of bacterial, viral and fungal infections in patients with cirrhosis. An observational, retrospective, historic cohort study. The exposed cohort included patients with cirrhosis with chronic use of PPI. The non-exposed cohort had not been using PPI. The follow-up period was 3 years, searching in the medical records for any events of bacterial infection confirmed by bacteriological culture. One hundred and thirteen patients met the selection criteria, 44 (39%) had chronic use of PPI; of them, 28 (63.6%) patients had not a clear clinical indication to justify the prescription of PPI. Twenty four (21.2%) patients developed bacterial infections during the follow-up period. In the univariate analysis, decompensated cirrhosis (Child B/C), presence of ascites, history of variceal bleeding, and chronic consumption of PPI were risk factors related to the development of infections. But, in the adjusted multivariate analysis only the chronic use of PPI was associated with development of infections (RR=3.6; 95% CI=1.1-12.3; P=0.04). There is an over-prescription of PPI without a justified clinical indication. The long-term consumption of PPI in patients with cirrhosis is associated with the development of bacterial infections; therefore these drugs must be carefully prescribed in this specific population.

Effect of prophylactic cefalexin treatment on the development of bacterial infection in acute radiation-induced dermatitis in dogs: a blinded randomized controlled prospective clinical trial.

Acute radiation-induced dermatitis (ARID) is a common sequela of radiation therapy and carries the risk of secondary bacterial skin infection. No standard of care exists for managing canine ARID and evidence-based guidelines are lacking; however, prophylactic use of antibiotics is common. To evaluate the impact of prophylactic cefalexin on the prevalence and severity of bacterial infection in canine ARID. Seventeen dogs treated with definitive-intent radiotherapy. All dogs were treated with definitive-intent radiation therapy (48-57.5 gray) targeted to the skin surface. Dogs were randomized to receive either prophylactic cefalexin (22 mg/kg twice daily) beginning halfway through the prescribed radiotherapy course (cohort A) or to serve as controls (cohort B). Aerobic skin cultures and surface cytological evaluation were performed at first onset of moist desquamation and one week following completion of radiation therapy. Skin toxicity grading and owner quality of life (QoL) questionnaires were performed weekly. The rate of infection, multidrug resistance status, toxicity severity and QoL between cohorts were compared. Staphylococcus schleiferi and S. pseudintermedius were the most frequent bacterial agents isolated in both cohorts. There was no significant difference in prevalence of bacterial infection or overall QoL between cohorts at either time point; however, multidrug-resistant infections were significantly increased in cohort A versus cohort B. Clinician- and client-perceived severity of toxicity was significantly greater and median duration of moist desquamation was significantly longer in cohort A than cohort B. Prophylactic use of cefalexin for management of canine ARID is not recommended.

CLINICO-MORPHOLOGICAL SUBSTANTIATION OF CLASSIFICATION OF HORSES' ULCERATIVE KERATITIS

Ulcerative keratitis is common animal disease, which is reported from all over the world and has quite a wide spread in some regions. A number of typical symptoms of ulcerative keratitis of sick horses were investigated in current research. It was found that pathology of the eyes can be observed in animals of different age groups belonging to both genders. A group of 40 horses owned by private stables of Moscow and Moscow region was selected to conduct the study. Current research was a clinical and morphological investigation, which included both ophthalmic method and a set of cytological and bacteriological examinations. Ulcerative keratitis of horses can be either a result of a minor injury of the cornea caused by awn grasses, seed hulls, leaves, sawdust and further bacterial infection development, prolonged use of antibiotics/corticosteroids or when dystrophic cornea is infected due to the microcirculatory processes disorder.

Multiscale modeling of bacterial colonies: how pili mediate the dynamics of single cells and cellular aggregates

Neisseria gonorrhoeae is the causative agent of one of the most common sexually transmitted diseases, gonorrhea. Over the past two decades there has been an alarming increase of reported gonorrhea cases where the bacteria were resistant to the most commonly used antibiotics thus prompting for alternative antimicrobial treatment strategies. The crucial step in this and many other bacterial infections is the formation of microcolonies, agglomerates consisting of up to several thousands of cells. The attachment and motility of cells on solid substrates as well as the cell–cell interactions are primarily mediated by type IV pili, long polymeric filaments protruding from the surface of cells. While the crucial role of pili in the assembly of microcolonies has been well recognized, the exact mechanisms of how they govern the formation and dynamics of microcolonies are still poorly understood. Here, we present a computational model of individual cells with explicit pili dynamics, force generation and pili–pili interactions. We employ the model to study a wide range of biological processes, such as the motility of individual cells on a surface, the heterogeneous cell motility within the large cell aggregates, and the merging dynamics and the self-assembly of microcolonies. The results of numerical simulations highlight the central role of pili generated forces in the formation of bacterial colonies and are in agreement with the available experimental observations. The model can quantify the behavior of multicellular bacterial colonies on biologically relevant temporal and spatial scales and can be easily adjusted to include the geometry and pili characteristics of various bacterial species. Ultimately, the combination of the microbiological experimental approach with the in silico model of bacterial colonies might provide new qualitative and quantitative insights on the development of bacterial infections and thus pave the way to new antimicrobial treatments.

Derinin Sık Görülen Bakteriyel Enfeksiyonları

Skin is an organ which is continuously in contact with microorganisms. In spite of this intense exposure to microorganisms, bacterial infection development is not observed because of many protective factors. Infections findings emerge when there is a distortion condition in one of the protective mechanisms. The mostly observed factors are staphylococci and streptococci. Bacterial infections of the skin are on the top of mostly observed diseases among the patients who applied to dermatology policlinic. In this manuscript, impetigo, ecthyma, erysipelas, cellulitis, lymphangitis, perianal streptococcal dermatitis, folliculitis, sycosis barbae, furuncle, carbuncle and paronychia will be described.