Gram-positive Bacterial Infections Research Articles

Contezolid: First Approval.

Contezolid 康替唑胺 (Youxitai 优喜泰®), an orally administered oxazolidinone antibacterial agent, is being developed by Shanghai MicuRx Pharmaceutical Co., Ltd. for the treatment of multidrug-resistant (MDR) Gram-positive bacterial infections, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci. In June 2021, it was approved by the National Medical Products Administration of China for the treatment of complicated skin and soft tissue infections (cSSTI), including, but not limited to, methicillin-susceptible S. aureus, MRSA, Streptococcus pyogenes and Streptococcus agalactiae. The recommended dosage of contezolid is 800 mg (i.e. two 400 mg tablets) every 12 h for 7–14 days. Contezolid is also undergoing clinical development for acute bacterial skin and skin structure infections (ABSSSI) in the USA, and for diabetic foot infections. This article summarizes the milestones in the development of contezolid leading to this first approval for the treatment of cSSTI.Supplementary InformationThe online version contains supplementary material available at 10.1007/s40265-021-01576-0.

The role of procalcitonin and presepsin in the septic febrile neutropenia in acute leukemia patients.

BackgroundThe source of bacterial infection in neutropenic acute leukemia patients is detected in about 20–30% of cases. Bacterial cultures may require a long incubation period and risk false-positive and false- negative results. Therefore, biomarkers distinguishing septic febrile neutropenia from other etiologies in acute leukemia patients play the important role in patient assessment and treatment planning. This study aims to determine the role of procalcitonin (PCT) and presepsin (PSPN) in infectious complication in comparison to C-reactive protein (CRP) on the first and third day at the onset of febrile neutropenia in patients with acute leukemia.MethodsBetween June 2018 and February 2019, 60 acute leukemia patients with febrile neutropenia receiving chemotherapy. The 41 acute myeloid leukemia patients and 19 acute lymphoblastic leukemia patients were recruited in this study. Their ages ranged from 14 to 65 years. PCT and PSPN were measured and were compared to CRP at the onset of febrile neutropenia and after 48 hours. 20 patients had a fever of unknown origin (FUO) and 40 patients had a bacterial infection.FindingsOur results showed that the values of these markers were higher in patients with infection than patients without. The area under the curve (AUC) of PCT were 0.931 and 0.813 on day one and three respectively, which was the best in determination of infection. The cut-off values of PCT were 1.27 and 1.23 ng/mL and the cut off values of PSPN were 1.75 and 2.9 μg/L in the successive days, their clinical sensitivities were high. PCT and PSPN were capable of distinguishing the cause of febrile neutropenia from the onset of infection and predicting its complications (p<0.05). The PSPN level couldn’t differentiate gram-positive or gram-negative bacterial infection. Significant differences were found between the mean values of the PSPN during the successive days in all patients and patients with bacteremia. This study illustrated a weak positive correlation between PCT and Sequential Organ Failure Assessment (SOFA) score, the negligible correlation between CRP and SOFA score and no significant correlation between PSPN and SOFA score.InterpretationPCT is an accurate biomarker in identifying infection in acute leukemia patients, its concentration is associated with the severity of bacterial sepsis. PSPN is superior to PCT for follow-up of patients.

Targeting SARS-CoV-2 main protease by teicoplanin: A mechanistic insight by docking, MM/GBSA and molecular dynamics simulation

First emerged in late December 2019, the outbreak of novel severe acute respiratory syndrome corona virus-2 (SARS-CoV-2) pandemic has instigated public-health emergency around the globe. Till date there is no specific therapeutic agent for this disease and hence, the world is craving to identify potential antiviral agents against SARS-CoV-2. The main protease (MPro) is considered as an attractive drug target for rational drug design against SARS-CoV-2 as it is known to play a crucial role in the viral replication and transcription. Teicoplanin is a glycopeptide class of antibiotic which is regularly used for treating Gram-positive bacterial infections, has shown potential therapeutic efficacy against SARS-CoV-2 in vitro. Therefore, in this study, a mechanistic insight of intermolecular interactions between teicoplanin and SARS-CoV-2 MPro has been scrutinized by molecular docking. Both monomeric and dimeric forms of MPro was used in docking involving blind as well as defined binding site based on the known inhibitor. Binding energies of teicoplanin-MPro complexes were estimated by Molecular Mechanics/Generalized Born Surface Area (MM/GBSA) computations from docking and simulated trajectories. The dynamic and thermodynamics constraints of docked drug in complex with target proteins under specific physiological conditions was ascertained by all-atom molecular dynamics simulation of 100 ns trajectory. Root mean square deviation and fluctuation of carbon α chain justified the stability of the bound complex in biological environments. The outcomes of current study are supposed to be fruitful in rational design of antiviral drugs against SARS-CoV-2.

Clinical Manifestations and Prognostic Factors of Fungal Keratitis: Analysis in Patients Over a 20-year Period

Purpose: To describe the clinical manifestations, causative organisms, treatment, and prognostic factors of fungal keratitis based on analysis of patients over the past 20 years. Methods: A total of 177 patients (177 eyes) with fungal keratitis, who were diagnosed by smears and cultures, were reviewed retrospectively. Sex, age, predisposing factors, causative organisms, clinical manifestations, treatment, and prognosis were evaluated. The patients were divided into three groups: only potassium hydroxide (KOH)-positive, only culture-positive, and KOH- and culture-positive. Logistic regression was performed to identify the factors associated with a poor clinical outcome. Results: The mean age of the patients was 67.4 ± 11.3 years; 107 (60.5%) patients were men. The most common predisposing factor was ocular trauma (57.6%), especially by plants (29.4%). The most prevalent filamentous fungi were Fusarium species (31.6%, 49 isolates), and the most prevalent yeasts were Candida species (11.0%, 17 isolates). In cases of bacterial and fungal keratitis, filamentous fungus with Gram-positive bacterial infection (70.7%, 29/41) was the most common presentation. Visual improvement after treatment was common in the KOH-positive group (79.2%, 19/24), while visual deterioration after treatment was common in the culture-positive group (40.4%, 36/89). Previous ocular disease (odds ratio [OR]: 3.744, p = 0.010), hypopyon (OR: 2.941, p = 0.030), and surgical treatment (OR: 24.482, p &lt; 0.001) were risk factors for a poor clinical outcome in the multivariate logistic regression model. Conclusions: Clinical prognosis was good in the KOH-positive only group, but poor in the culture-positive group. If fungal keratitis is suspected, diagnostic KOH staining and culture tests should be performed initially. Early intensive antifungal medical treatments are necessary for patients with risk factors for poor clinical outcomes.

Is Neutrophil-Lymphocyte Count Ratio a Better Indicator of Sepsis with Gram-positive Bacterial Infection?

BackgroundSepsis is the main cause of death in infectious diseases that can be caused by gram-negative or gram-positive bacteria. Definitive therapy for sepsis is antibiotics, depending on blood culture results even though it takes time for bacterial growth. Neutrophil–lymphocyte count ratio (NLCR) is a laboratory parameter that can predict bacterial infection in sepsis patients. NLCR is time-and-cost-effective and easy-to-use in daily practice, in sepsis patients infected with gram-negative, gram-positive, and no bacterial growth based on blood culture results.Materials and methodsThis was a comparative study of NLCR and the result of blood culture from sepsis patients. Subjects were obtained from the medical records of patients admitted to our hospital from January 2019 to May 2019. Patients aged over 18 years who were diagnosed with sepsis and had blood culture information were included. Patients with hematological disorder and malignancy were excluded. Sepsis data consisted of gender, age, source of infection, comorbidity, NLCR, and blood culture results.ResultsNinety-four sepsis subjects met the inclusion criteria, and fifty-one subjects (54.25%)—33 subjects (35.10%) with gram-negative bacterial infection and 18 subjects (19.15%) with gram-positive bacterial infection—were included in the analysis due to the completeness of the data. The median NLCR (IQR) was 17.8 (14.3–30.7) in gram-negative, 31.5 (26.3–95.0) in gram-positive, and 22.8 (15.67–22.75) in no bacterial growth (p = 0.001).ConclusionNLCR can distinguish gram-negative and gram-positive bacterial infections. It also can predict the possibility of pathogenic bacteria that cause sepsis.How to cite this articleSumardi U, Prihardianti DR, Sudjana P. Is Neutrophil–Lymphocyte Count Ratio a Better Indicator of Sepsis with Gram-positive Bacterial Infection? Indian J Crit Care Med 2021;25(7):795–799.

Alkyl-Aryl-Vancomycins: Multimodal Glycopeptides with Weak Dependence on the Bacterial Metabolic State.

Resistance to last-resort antibiotics such as vancomycin for Gram-positive bacterial infections necessitates the development of new therapeutics. Furthermore, the ability of bacteria to survive antibiotic therapy through formation of biofilms and persister cells complicates treatment. Toward this, we report alkyl-aryl-vancomycins (AAVs), with high potency against vancomycin-resistant enterococci and staphylococci. Unlike vancomycin, the lead compound AAV-qC10 was bactericidal and weakly dependent on bacterial metabolism. This resulted in complete eradication of non-growing cells of MRSA and disruption of its biofilms. In addition to inhibiting cell wall biosynthesis like vancomycin, AAV-qC10 also depolarizes and permeabilizes the membrane. More importantly, the compound delocalized the cell division protein MinD, thereby impairing bacterial growth through multiple pathways. The potential of AAV-qC10 is exemplified by its superior efficacy against MRSA in a murine thigh infection model as compared to vancomycin. This work paves the way for structural optimization and drug development for combating drug-resistant bacterial infections.

Value of procalcitonin and critical illness score in etiological diagnosis and prognosis of sepsis caused by intra-abdominal infections

To compare the early and late predictive values of critical illness score (CIS) and procalcitonin (PCT) in septic patients with blood stream infection (BSI) induced by intra-abdominal infection (IAI), and to identify the value of PCT in etiological diagnosis. The clinical data of patients with at least one positive blood culture within 24 hours admission to the emergency department of China-Japan Friendship Hospital from January 2014 to December 2019 and with final diagnosis of IAI induced sepsis were enrolled. Sequential organ failure assessment (SOFA), mortality in emergency department sepsis (MEDS), Logistic organ dysfunction system (LODS), and acute physiology and chronic health evaluation II (APACHE II) scores were calculated based on the parameters on the day of admission. Differences in various indicators among different Gram-stained bacterial infections and among patients with different prognosis at 28 days or 60 days were compared. Receiver operator characteristic curve (ROC curve) was used to analyze the value of PCT in differential etiological diagnosis of IAI induced sepsis caused by single bacterial infection, and the predictive value of CIS and PCT on 28-day and 60-day death of septic patients with BSI induced by IAI. A total of 221 septic patients with IAI caused by single bacterial infection were enrolled. The 28-day mortality was 19.9% (44/221), and the 60-day mortality was 25.8% (57/221). Mortality caused by Gram-positive (G+) bacterial infection of patients was significantly higher than that caused by Gram-negative (G-) bacterial infection (28 days: 34.6% vs. 11.4%, 60 days: 42.0% vs. 16.4%, both P < 0.01). Compared with patients with G+ bacterial infection, the PCT value of patients with G- bacterial infection was higher [μg/L: 4.31 (0.71, 25.71) vs. 1.29 (0.32, 10.83), P < 0.05]. Compared with survival group, the values of CIS and PCT in death group were higher, either in 28 days or in 60 days [death group vs. survival group in 28 days: SOFA score was 6.0 (4.0, 10.0) vs. 3.0 (2.0, 5.0), MEDS score: 11 (9, 14) vs. 6 (6, 9), LODS score: 4.0 (2.0, 6.0) vs. 1.0 (0, 2.0), APACHE II score: 17.0 (15.0, 24.0) vs. 12.0 (8.0, 15.0), PCT (μg/L): 3.48 (1.01, 26.70) vs. 2.45 (0.32, 15.65); death group vs. survival group in 60 days: SOFA score: 6.0 (4.0, 10.0) vs. 3.0 (2.0, 5.0), MEDS score: 9 (6, 14) vs. 6 (6, 9), LODS score: 4.0 (1.0, 5.0) vs. 1.0 (0, 2.0), APACHE II score: 16.5 (12.0, 20.0) vs. 12.0 (8.0, 15.0), PCT (μg/L): 2.67 (0.98, 17.73) vs. 2.22 (0.31, 16.75); all P < 0.05]. ROC curve showed that: (1) the area under ROC curve (AUC) of PCT in the diagnosis of IAI induced sepsis with single bacterial infection was 0.740 [95% confidence interval (95%CI) was 0.648-0.833]. When the optimal cut-off value of PCT was 1.82 μg/L, the sensitivity of diagnosis of G- bacterial infection was 74.0%, and the specificity was 68.2%. When PCT value was higher than 10.92 μg/L, the specificity of diagnosis of G- bacterial infection could reach 81.8%. (2) In the prediction of 28-day and 60-day mortality for septic patients with BSI induced by IAI, the APACHE II score achieved the highest AUC [28 days: 0.791 (95%CI was 0.680-0.902), 60 days: 0.748 (95%CI was 0.645-0.851)]. APACHE II score higher than 14.5 could help to predict 28-day and 60-day mortality for IAI patients with negative predictive values of 94.9% and 88.5%. However, the predictive value of PCT for septic patients with BSI induced by IAI was relatively lower [28-day AUC: 0.610 (95%CI was 0.495-0.725), 60-day AUC: 0.558 (95%CI was 0.450-0.667)]. PCT is more reliable in the identification of pathogen type among IAI induced sepsis with BSI, while APACHE II score may perform better in predicting early and late mortality.

Associations Between Patient Neighborhood Characteristics and Inappropriate Antimicrobial Use

Background: Antimicrobials are among the most commonly prescribed medications in US hospitals; an estimated 50% of hospitalized patients receive an antimicrobial. Research has shown that antimicrobial prescriptions to vary by patient- and hospital-level factors; however, disparities by patient neighborhood characteristics have not been examined. We evaluated associations between hospital and neighborhood indicators of socioeconomic status (SES) and antimicrobial use (AU) for gram-positive bacterial infections (GPBs), and broad-spectrum use for community-acquired infections (BSCAs) and hospital-onset infections (BSHOs). Methods: This analysis was conducted among 86 acute-care hospitals in California that submitted AU data via the NHSN in 2019. Hospital-level AU was measured as standardized antimicrobial administration ratios (SAARs) calculated by dividing observed antimicrobial use by risk-adjusted predicted antimicrobial use for GPB, BSCA, and BSHO antimicrobial groupings and categorized as binary (&gt;1 or &lt;1); SAARs &gt;1 indicate potential inappropriate prescribing. California Office of Statewide Health Planning and Development 2018 data were used to obtain hospital characteristics and patient age, race or ethnicity, insurance, and comorbidities (defined by Charlson comorbidity index) for hospitalizations where AU may have been indicated, based on International Classification of Diseases Tenth Revision (ICD-10) diagnosis codes. The California Healthy Places Index (HPI) was used to obtain composite neighborhood SES indicators for each patient at the ZIP code level, measured as tertiles. Covariates were aggregated to the hospital level. Poisson regressions were used to evaluate the association between hospital and neighborhood SES indicators and SAAR scores, controlling for potential hospital-level confounders. Results: Among 86 hospitals included in the analysis, the mean patient age for hospitalizations where AU may have been indicated was 66 years, the proportion of white patients was 55%, and the mean proportion of Medi-Cal users was 19%. After adjusting for confounders including age, race or ethnicity, insurance status, comorbidities, and number of hospital beds; higher median values of patient SES had a protective effect against hospitals having GP SAAR scores &gt; 1 (relative risk [RR], 0.68; 95% CI, 0.50–0.93) but was not significantly associated with hospitals having BSCA SAAR scores &gt;1 (RR, 0.79; 95% CI, 0.62–1.02) or BSHO SAAR scores &gt;1 (RR, 0.80; 95% CI, 0.61–1.04). Conclusions: Considering SES in addition to summary antimicrobial use scores such as SAARs may help identify populations potentially at risk for inappropriate AU; however, patient-level information is still necessary to evaluate appropriateness of antimicrobial prescribing.Funding: NoDisclosures: None

LncRNA-CR46018 positively regulates the Drosophila Toll immune response by interacting with Dif/Dorsal

The Toll signaling pathway is highly conserved from insects to mammals. Drosophila is a model species that is commonly used to study innate immunity. Although many studies have assessed protein-coding genes that regulate the Toll pathway, it is unclear whether long noncoding RNAs (lncRNAs) play regulatory roles in the Toll pathway. Here, we evaluated the expression of the lncRNA CR46018 in Drosophila. Our results showed that this lncRNA was significantly overexpressed after infection of Drosophila with Micrococcus luteus. A CR46018-overexpressing Drosophila strain was then constructed; we expected that CR46018 overexpression would enhance the expression of various antimicrobial peptides downstream of the Toll pathway, regardless of infection with M. luteus. RNA-seq analysis of CR46018-overexpressing Drosophila after infection with M. luteus showed that upregulated genes were mainly enriched in Toll and Imd signaling pathways. Moreover, bioinformatics predictions and RNA-immunoprecipitation experiments showed that CR46018 interacted with the transcription factors Dif and Dorsal to enhance the Toll pathway. During gram-positive bacterial infection, flies overexpressing CR46018 showed favorable survival compared with flies in the control group. Overall, our current work not only reveals a new immune regulatory factor, lncRNA-CR46018, and explores its potential regulatory model, but also provides a new perspective for the effect of immune disorders on the survival of Drosophila melanogaster.

Management of Febrile Neutropenia in Children with Cancer

Febrile neutropenia (FN) is the most common complication of childhood cancer treatment with mortality rates of untreated patients up to 21%. The recognition and management of FN is fundamental to preserve the children health status and avoid life-threatening complications. Physical and laboratory assessments should be performed in every patient with FN to identify any potential site of infection to be promptly treated. Hence, an empiric antimicrobial therapy remains the gold standard for the management of these patients. Antimicrobial treatment should be based on local epidemiological data and antibiotic susceptibility; a combination of a fourth-generation antipseudomonal cephalosporin with an aminoglycoside is generally adopted. Empirical administration of glycopeptides, in absence of documented Gram-positive bacterial infection is not recommended for routine use. Despite the progress in the management of febrile neutropenia and its relatively low mortality, the emergence of resistant pathogens is increasing, and the development of new effective antimicrobials are needed. Established criteria for a risk adapted approach is still lacking and no definitive data supporting the duration of empiric treatment are present. De-escalation strategies should be implemented to reduce both antibiotic exposure and resistance as well as hospital stay.

Design, synthesis, and antibacterial evaluation of vancomycin-LPS binding peptide conjugates

Developing novel antibiotics is urgently needed with emergency of drug resistance. Vancomycin, the last resort for intractable Gram-positive bacterial infections, is ineffective against Gram-negative bacteria and vancomycin resistant bacteria. Herein, we report a series of novel vancomycin derivatives carrying LPS binding peptides, vancomycin-LPS binding peptide conjugates (VPCs). The LPS binding peptides were conjugated onto 4 sites of vancomycin via CuAAC or maleimide- sulfydryl addition, and the formed VPCs were screened against VISA/VRE and Gram-negative strains. VPCs exhibited enhanced activity against vancomycin resistant bacteria and obtained the activity against Gram-negative bacteria in vitro, providing a novel strategy for vancomycin modification and glycopeptide antibiotics synthesis.

CD137 Signaling Is Critical in Fungal Clearance during Systemic Candida albicans Infection.

Invasive fungal infections by Candida albicans frequently cause mortality in immunocompromised patients. Neutrophils are particularly important for fungal clearance during systemic C. albican infection, yet little has been known regarding which surface receptor controls neutrophils’ antifungal activities. CD137, which is encoded by Tnfrsf9, belongs to the tumor necrosis receptor superfamily and has been shown to regulate neutrophils in Gram-positive bacterial infection. Here, we used genetic and immunological tools to probe the involvement of neutrophil CD137 signaling in innate defense mechanisms against systemic C. albicans infection. We first found that Tnfrsf9−/− mice were susceptible to C. albicans infection, whereas injection of anti-CD137 agonistic antibody protected the host from infection, suggesting that CD137 signaling is indispensable for innate immunity against C. albicans infection. Priming of isolated neutrophils with anti-CD137 antibody promoted their phagocytic and fungicidal activities through phospholipase C. In addition, injection of anti-CD137 antibody significantly augmented restriction of fungal growth in Tnfrsf9−/− mice that received wild-type (WT) neutrophils. In conclusion, our results demonstrate that CD137 signaling contributes to defense mechanisms against systemic C. albicans infection by promoting rapid fungal clearance.

Impact of Donor-Derived Multi-drug–Resistant Organism Infections on Abdominal Solid Organ Transplantation Recipients in China

Infection with multi-drug-resistant organisms (MDROs) is a life-threatening disease among abdominal solid organ transplantation recipients. Reports of donor-derived (DD) MDRO infections were few, but adverse clinical outcomes were severe, such as death or graft loss. The medical records of 68 donation after citizens' death donors with MDRO infections and 20 recipients transmitted with infections between October 1, 2015, and September 1, 2020, were reviewed according to the Declaration of Helsinki and the Declaration of Istanbul. There were no grafts from prisoners, and no donors were not coerced or paid. Prevalence and mortality of DD-MDRO infection among abdominal solid organ transplantation recipients were 2.3% and 18.1%, respectively. The prevalence rate of DD-MDR gram-negative bacterial infection was higher than that of gram-positive bacterial infection (1.7% vs 0.6%). Negative culture of specimens occurred in 9 of 68 donors. Recipients with DD-MDR gram-negative bacterial infections had a significantly lower survival rate compared with DD-MDR gram-positive bacterial infections (P=.046). Donation after citizens' death donors and recipients had high MDRO infection rates, and gram-negative bacteria were the predominant pathogens. When a possible DD-MDRO infection occurs, there may be adverse outcomes with limited choice of antibiotics. A nationwide surveillance and communication network needs to be established in China.

Understanding the Mechanism of YhdP in Modulation of the OM‐Permeability Barrier in Stationary Phase in Escherichia coli

Background The emergence of resistance among the most important bacterial pathogens is recognized as a major public threat worldwide. The impermeable outer membrane (OM) of gram-negative bacteria plays a significant role in withstanding antibiotic stresses as it is impervious to both large and hydrophobic molecules, very much limiting the access of different antibiotics to cells. Most of the antibiotics that are used to treat gram-positive bacterial infections are ineffective against gram-negative bacteria. To make these antibiotics effective against gram-negative bacteria, mechanism of the OM permeability barrier needs to be revisited. Many factors of outer surface are involved in maintaining of OM-integrity. One of those factor is ECA (Enterobacterial Common Antigen). It is a conserved molecule which presents only in the Enterobacterales’s order. Mitchel et al. (2018) have reported a novel function of the cyclic ECA molecule in maintaining the permeability barrier of the OM in a YhdP (inner-membrane protein) dependent manner in E. coli. Nevertheless, we do not know the mechanism through which YhdP and ECA affect OM-permeability. We are trying to find this mechanism by exploring a ∆yhdP∆fadR double mutant. Methods Knockout of ΔyhdPΔfadR and other E. coli strains were generated by P1 phase transduction method. Growth curve was done in 96-well plate at different temperatures (30°C, 37°C, and 42°C). Antibiotic sensitivity was done by disc diffusion and EOPs methods. Suppressor mutants were identified by transposon mutagenesis approach. Results We have found that the ∆yhdP ∆fadR double mutant is very sick at 30°C as compared to wild type, a phenotype which is specific to lower temperatures. In addition, we have screened various antibiotics against them and found that the double mutant is sensitive to benzalkonium chloride (cationic surfactant) and bacitracin (polypeptide). Deletion of fadR alone has slight effect on the growth of E. coli and it is sensitive to benzalkonium chloride. In silico database suggests that YhdP interacts with YdgH (a periplasmic protein of unknown function). To find the defect of this double mutant (∆yhdP ∆fadR), we have isolated suppressor mutants. These suppressor mutants were generated by plating the double mutant on LB plate, and allowing growth at 30°C overnight. The isolated suppressor mutants can grow at 30°C. The identified mutants are uspB::Tn10, pitA::Tn10, leuO::Tn10, and hycC::Tn10.We are currently exploring these suppressor mutants. Conclusion YhdP-FadR interaction is essential for survival at 30°C. Generation of suppressor mutants make the ∆yhdP∆fadR mutant to survive at low temperature. One of the identified suppressor mutants, leuO plays an important role in low temperature (Klauck et al., 1997; Repoila & Gottesman, 2003).This indicates that LeuO might be involved in of bacterial growth at 30°C. These studies will lead to better understanding of resistance mechanisms in gram-negative bacteria and help in target-based designing of antibiotics.

Activation of human skin mast cells by vancomycin via MrgX2: Comparison to the effects of brimonidine

Abstract Vancomycin (VCM) is a glycopeptide antibiotic that inhibits bacterial peptidoglycan biosynthesis and is used for the treatment of certain Gram-positive bacterial infections of the eyes. However, the use of VCM is associated with several potential adverse reactions. We examined the mechanism of activation of human mast cells by vancomycin (VCM) and compared to brimonidine, an alpha2-adrenergic receptor agonist used to treat in glaucoma. VCM induced degranulation and cytokine secretion by SMCs, which were suppressed by pertussis toxin (PTX) (similar to MrgX2 ligands). Brimonidine induced less degranulation than VCM that was partially inhibited by PTX. MrgX2 expression on the surface of SMCs was detected by FACS analysis. VCM enhanced FceRI-mediated degranulation and cytokine secretion in a dose-dependent manner, whereas brimonidine failed to induce cytokine production and suppressed FceRI-mediated cytokine secretion. VCM induced maximal ERK-phosphorylation by 5 min similar to compound 48/80, an MrgX2 ligand and inhibited by PTX. VCM- but not brimonidine-induced degranulation of MCs was significantly inhibited by QWF, an MrgX2 antagonist. This study indicates that VCM but not brimonidine activates human SMCs via MrgX2 and that MCs become more responsive to VCM when co-stimulated by aggregating FceRI, which may occur when sensitive patients exposed to aeroallergen and VCM.

Suppression of breathing by Gram‐positive bacterial proteins in neonatal Sprague Dawley rat pups

Preterm infants regularly present with immature and unstable respiratory control networks at birth leading to oxygen dysregulation in the newborn (Hofstetter et al., 2007). Sequentially, the requirement for prolonged medical support and hospital stays increases the risk of late-onset infection. Hypoxic stress during early life can alter central networks that control the cardiorespiratory system with profound autonomic dysregulation. We hypothesised that chronic neonatal exposure to intermittent hypoxia and hyperoxia (cIHH) with subsequent Gram-positive bacterial infection alters respiratory control. On postnatal day (PND) three, Sprague Dawley litters were exposed for 10 days to either cIHH or room air gas exposure. On PND13, pups were studied using whole body plethysmography at 30◦C. After an initial acclimatisation period, a baseline normoxic measurement was taken. Following intraperitoneal administration of lipoteichoic acid and peptidoglycan (LTA+PGN) or pyro-free saline (n=10 per group), animals were monitored for 3 hours under normoxic conditions. Oxygen dysregulation in early life in and of itself, did not alter breathing frequency (P=0.37) or minute ventilation (P=0.07). Administration of LTA+PGN suppressed breathing as shown by a decrease in frequency and minute ventilation (both P<0.05). Furthermore, administration of LTA+PGN on PND13 increased cytokine expression in both sexes as well as corticosterone concentration in male pups compared to relevant controls. Administration of LTA+PGN did not significantly alter rectal temperature compared to controls. Neonatal infection remains a significant challenge, with a paucity of studies investigating the response to Gram-positive bacterial proteins despite its clinical relevance. We report that Gram-positive bacterial proteins can quickly suppress breathing frequency and elicit both an inflammatory and stress response. Further studies are necessary to elucidate the mechanisms underlying aberrant respiratory control. References Hofstetter AO, Legnevall L & Ericherleniuskise EH (2007). Cardiorespiratory development in extremely preterm infants: vulnerability to infection and persistence of events beyond term-equivalent age. 285–292.

Cranial Mandibular Fibrosis Syndrome in Adult Farmed Rainbow Trout Oncorhynchus mykiss.

An unusual condition affecting market size rainbow trout was investigated. This condition was prevalent for several years at low levels but affected a large proportion of stock during 2018 and 2019. Chronic fibrosis affecting cranial tissues and the jaw was observed in samples collected in 2018. A larger sampling was then conducted in 2019 to investigate the presence of an infectious agent(s). An extensive inflammatory response in the mandibular region was the main finding, however infectious agents in the lesions were not identified through classical virology and bacteriology analysis. Tetracapsuloides bryosalmonae infection, calcinosis, and a Gram-positive bacterial infection of a single fish cardiac tissue was observed, however, a correlation of these pathologies and the cranial mandibular fibrosis (CMF) syndrome was not established. The gene expression of a panel of 16 immune-related genes was studied. Among these, tgf-b, sIgM, il11, hspa, and the antimicrobial peptides lys and cath1 were up-regulated in jaw sections of CMF-affected fish, showing a strong positive correlation with the severity of the lesions. Idiopathic chronic fibrosis with the activation of the Tfg-B pathway and local hyper-immunoglobulaemia was therefore diagnosed. Initiating factors and causative agent(s) (biotic or abiotic) of CMF remain, at present, unclear.

Dalbavancin Efficacy and Impact on Hospital Length-of-Stay and Treatment Costs in Different Gram-Positive Bacterial Infections

Background and ObjectivesThe study aimed to evaluate the impact of dalbavancin therapy on both hospital length-of-stay (LOS) and treatment-related costs, as well as to describe the clinical outcome, in a retrospective cohort of patients with diverse Gram-positive bacterial infections, hospitalized in different specialty Units.MethodsFrom July 2017 to July 2019, clinical and sociodemographic data were collected for all hospitalized patients switched to dalbavancin for the treatment of Gram-positive infections. LOS and treatment-related costs were assessed and compared to a hypothetical scenario where the initial standard antimicrobial therapy would have been administered in hospital for the same duration as dalbavancin.ResultsA total of 50 patients were enrolled. The observed infections were: acute bacterial skin and skin structure infections (ABSSSIs, 12 patients), complicated ABSSSIs (eight patients), osteoarticular infections (18 patients), vascular graft or cardiovascular implantable electronic devices (CIED) infections (12 patients). After a median of 14 [interquartile range (IQR) 7–28] days, the in-hospital antimicrobial therapy was switched to dalbavancin 1500 mg. When appropriate, considering the site and the clinical course of the infection, 1500 mg doses were repeated every 14 days until recovery. Overall, 49/50 (98%) patients reported clinical success at the end of therapy. No relapses were observed in 37 patients for whom a median follow-up of 150 (IQR 30–180) days was available. By switching to dalbavancin, a median of €8,259 (IQR 5644–17,270) and 14 hospital days (IQR 22–47) per patient were saved.ConclusionsIn this experience, the use of dalbavancin contributed to shorten LOS and treatment-related costs, especially in difficult Gram-positive infections requiring prolonged therapy.

Modeling Approach to Optimizing Dose Regimen of Vancomycin for Chinese Pediatric Patients with Gram-Positive Bacterial Infections.

The aim of this study was to establish the population pharmacokinetics (PK) model of Vancomycin for Chinese pediatric patients which can extrapolate to whole age periods by bridging the published adult population PK model and the established pediatric population PK model. The final consolidated population PK model was used to explore the correlation of pharmacokinetics/pharmacodynamics (PK/PD) indices and efficacy of vancomycin and to provide evidence for the optimized regimen of vancomycin in Chinese pediatric patients with Gram-positive bacterial infection. 108 pediatric patients with Gram-positive infections from 2 pediatric hospitals in China in the first period of the prospective multi-center vancomycin clinical observational study were enrolled to establish the population PK model. A one-compartment population PK model was established and validated. The correlation between vancomycin PK/PD indices [trough concentration (Cmin), peak concentration (Cmax), 0–24 h area under the curve (AUC0–24) and the area under the curve to minimum inhibitory concentration ratio (AUC0–24/MIC)] and the overall clinical outcomes (clinical efficacy and microbiological efficacy) in Chinese pediatric patients were evaluated. There is no significant correlation between PK/PD indices and clinical efficacy or microbiological efficacy. Considering the high clinical effective rate (>90%) and median AUC0–24/MIC values of 200–300, Chinese pediatric patients with Gram-positive bacterial infection may be suitable for lower AUC0–24/MIC target value compared to the target value of 400–600 recommended by IDSA guideline. Different optimal dose regimen of vancomycin for Chinese pediatric patients should be considered. Further evaluation in more prospective studies will be needed.

The Pattern of Microorganisms and Drug Susceptibility in Pediatric Oncologic Patients with Febrile Neutropenia

Objective The study aimed to describe the pattern of causative microorganisms, drug susceptibility, risk factors of antibiotic-resistant bacterial infection, and clinical impact of these organisms on pediatric oncology patients with febrile neutropenia. Methods A retrospective descriptive study of oncologic patients aged less than 15 years who were diagnosed with febrile neutropenia in King Chulalongkorn Memorial Hospital was conducted between January 2013 to December 2017. Characteristics and clinical outcomes of febrile neutropenia episodes, causative pathogens, and their antibiotic susceptibilities were recorded. Result This study included 267 patients with 563 febrile neutropenia episodes. The median (range) age was 5.1 years (1 month–15 years). The most common underlying disease was acute lymphoblastic leukemia (42.7%). Of 563 febrile episodes, there were 192 (34.1%) with microbiologically documented infection. Among these 192 episodes of microbiologically documented infection, there were 214 causative pathogens: 154 bacteria (72%), 32 viruses (15%), 27 fungus (12.6%), and 1 Mycobacterium tuberculosis (0.4%). Gram-negative bacteria (48.6%) accounted for most of the causative pathogens. Twenty-three percent of them were multidrug resistant, and 18% were carbapenem resistant. Among Gram-positive bacterial infection which accounted for 23.4% of all specimens, the proportion of MRSA was 20%. The 2-week mortality rate was 3.7%. Drug-resistant Gram-negative bacterial infection caused significant adverse events and mortality compared to nonresistant bacterial infection (p < 0.05). Conclusion There is high rate of drug-resistant organism infection in pediatric oncology patients in a tertiary-care center in Thailand. Infection with drug-resistant Gram-negative bacterial infection was associated with significant morbidity and mortality. Continuous surveillance for the pattern of drug-resistant infections is crucial.