Prepandemic viral community-acquired pneumonia: Diagnostic sensitivity and specificity of nasopharyngeal swabs and performance of clinical severity scores.

The objectives of this work were to assess the diagnostic sensitivity and specificity of nasopharyngeal (NP) swabs for viral community-acquired pneumonia (CAP) and the performance of pneumonia severity index (PSI) and CURB-65 severity scores in the viral CAP in adults. A prospective observational cohort study of consecutive 341 hospitalized adults with CAP was performed between January 2018 and March 2020. Demographics, comorbidities, symptoms/signs, analytical data, severity scores, antimicrobials, and outcomes were recorded. Blood, NP swabs, sputum, and urine samples were collected at admission and assayed by multiplex real time-PCR, bacterial cultures, and Streptococcus pneumoniae and Legionella pneumophila antigens detection, to determine the etiologies and quantify the viral load. The etiology was identified in 174 (51.0%) patients, and in 85 (24.9%) it was viral, the most frequent rhinovirus and influenza virus. The sensitivity of viral detection in sputum (50.7%) was higher than in NP swabs (20.9%). Compared with sputum, the positive predictive value and specificity of NP swabs for viral diagnosis were 95.8% and 96.9%, respectively. Performance of PSI and CURB-65 scores in all CAP with etiologic diagnosis were as expected, with mortality associated with higher values, but they were not associated with mortality in patients with viral pneumonia. NP swabs have lower sensitivity but high specificity for the diagnosis of viral CAP in adults compared with sputum, reinforcing the use NP swabs for the diagnostic etiology work-up. The PSI and CURB-65 scores did not predict mortality in the viral CAP, suggesting that they need to be updated scores based on the identification of the etiological agent.

Development and validation of a prediction model for 30-day mortality in hospitalised patients with COVID-19: the COVID-19 SEIMC score.

OBJECTIVE: To develop and validate a prediction model of mortality in patients with COVID-19 attending hospital emergency rooms. DESIGN: Multivariable prognostic prediction model. SETTING: 127 Spanish hospitals. PARTICIPANTS: Derivation (DC) and external validation (VC) cohorts were obtained from multicentre and single-centre databases, including 4035 and 2126 patients with confirmed COVID-19, respectively. INTERVENTIONS: Prognostic variables were identified using multivariable logistic regression. MAIN OUTCOME MEASURES: 30-day mortality. RESULTS: Patients' characteristics in the DC and VC were median age 70 and 61 years, male sex 61.0% and 47.9%, median time from onset of symptoms to admission 5 and 8 days, and 30-day mortality 26.6% and 15.5%, respectively. Age, low age-adjusted saturation of oxygen, neutrophil-to-lymphocyte ratio, estimated glomerular filtration rate by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, dyspnoea and sex were the strongest predictors of mortality. Calibration and discrimination were satisfactory with an area under the receiver operating characteristic curve with a 95% CI for prediction of 30-day mortality of 0.822 (0.806-0.837) in the DC and 0.845 (0.819-0.870) in the VC. A simplified score system ranging from 0 to 30 to predict 30-day mortality was also developed. The risk was considered to be low with 0-2 points (0%-2.1%), moderate with 3-5 (4.7%-6.3%), high with 6-8 (10.6%-19.5%) and very high with 9-30 (27.7%-100%). CONCLUSIONS: A simple prediction score, based on readily available clinical and laboratory data, provides a useful tool to predict 30-day mortality probability with a high degree of accuracy among hospitalised patients with COVID-19.

Design, synthesis and in vitro biological evaluation of a novel class of anti-adenovirus agents based on 3-amino-1,2-propanediol.

Nowadays there is not an effective drug for the treatment of infections caused by human adenovirus (HAdV) which supposes a clinical challenge, especially for paediatric and immunosuppressed patients. Here, we describe the design, synthesis and biological evaluation as anti-adenovirus agents of a new library (57 compounds) of diester, monoester and triazole derivatives based on 3-amino-1,2-propanediol skeleton. Seven compounds (17, 20, 26, 34, 44, 60 and 66) were selected based on their high anti-HAdV activity at low micromolar concentration (IC50 from 2.47 to 5.75 µM) and low cytotoxicity (CC50 from 28.70 to >200 µM). In addition, our mechanistic assays revealed that compounds 20 and 44 might be targeting specifically the HAdV DNA replication process, and compound 66 would be targeting HAdV E1A mRNA transcription. For compounds 17, 20, 34 and 60, the mechanism of action seems to be associated with later steps after HAdV DNA replication.

Discovery of a Small Molecule Inhibitor of Human Adenovirus Capable of Preventing Escape from the Endosome.

Human adenoviruses (HAdVs) display a wide range of tissue tropism and can cause an array of symptoms from mild respiratory illnesses to disseminated and life-threatening infections in immunocompromised individuals. However, no antiviral drug has been approved specifically for the treatment of HAdV infections. Herein, we report our continued efforts to optimize salicylamide derivatives and discover compound 16 (JMX0493) as a potent inhibitor of HAdV infection. Compound 16 displays submicromolar IC50 values, a higher selectivity index (SI > 100) and 2.5-fold virus yield reduction compared to our hit compound niclosamide. Moreover, unlike niclosamide, our mechanistic studies suggest that the antiviral activity of compound 16 against HAdV is achieved through the inhibition of viral particle escape from the endosome, which bars subsequent uncoating and the presentation of lytic protein VI.

Role of PstS in the Pathogenesis of Acinetobacter baumannii Under Microaerobiosis and Normoxia.

Acinetobacter baumannii is a successful pathogen responsible for infections with high mortality rate. During the course of infection it can be found in microaerobic environments, which influences virulence factor expression. From a previous transcriptomic analysis of A. baumannii ATCC 17978 under microaerobiosis, we know the gene pstS is overexpressed under microaerobiosis. Here, we studied its role in A. baumannii virulence. pstS loss significantly decreased bacterial adherence and invasion into A549 cells and increased A549 cell viability. pstS loss also reduced motility and biofilm-forming ability of A. baumannii. In a peritoneal sepsis murine model, the minimum lethal dose required by A. baumannii ATCC 17978 ΔpstS was lower compared to the wild type (4.3 vs 3.2 log colony forming units/mL, respectively), and the bacterial burden in tissues and fluids was lower. Thus, the loss of the phosphate sensor PstS produced a decrease in A. baumannii pathogenesis, supporting its role as a virulence factor.

Repositioning rafoxanide to treat Gram-negative bacilli infections.

OBJECTIVES: Repurposing drugs provides a new approach to the fight against MDR Gram-negative bacilli (MDR-GNB). Rafoxanide, a veterinary antihelminthic drug, has shown antibacterial activity in vitro against Gram-positive bacteria. We aimed to analyse the in vitro and in vivo efficacy of rafoxanide in combination with colistin against colistin-susceptible (Col-S) and colistin-resistant (Col-R) GNB. METHODS: A collection of Col-S and Col-R Acinetobacter baumannii, Pseudomonas aeruginosa and Klebsiella pneumoniae were used. Chequerboard and time-kill curve analyses were performed to determine the synergy between rafoxanide and colistin. Changes in membrane structure and permeability were analysed using transmission electron microscopy and fluorescence assays. A murine peritoneal sepsis model using Col-R strains of these pathogens was performed to study the efficacy of rafoxanide (10 mg/kg/24 h, IV), colistimethate sodium (CMS) (20 mg/kg/8 h, intraperitoneally) and rafoxanide (10 mg/kg/24 h, IV) plus CMS (20 mg/kg/8 h, intraperitoneally) for 72 h. RESULTS: Rafoxanide showed MICs ≥256 mg/L for all Col-S and Col-R strains. Chequerboard and time-kill curve analyses showed that rafoxanide (1 mg/L) is more synergistic with colistin against Col-R than Col-S strains. Col-R, but not Col-S, strains treated with rafoxanide demonstrated higher membrane permeabilization. Transmission electron microscopy visualization confirmed that Col-R strains suffer morphological changes. In the murine peritoneal sepsis model with Col-R strains, rafoxanide plus CMS, compared with CMS alone, increased mouse survival to 53.8% and 73.3%, and reduced bacterial loads in tissues and blood between 2.34 and 4.99 log10 cfu/g or mL, respectively. CONCLUSIONS: Rafoxanide repurposing, as monotherapy and in combination with CMS, may address the urgent need for new treatments for infections caused by MDR-GNB.

Extended-spectrum resistance to ß-lactams/ß-lactamase inhibitors (ESRI) evolved from low-level resistant Escherichia coli.

OBJECTIVES: Escherichia coli is characterized by three resistance patterns to ß-lactams/ß-lactamase inhibitors (BLs/BLIs): (i) resistance to ampicillin/sulbactam and susceptibility to amoxicillin/clavulanic acid and piperacillin/tazobactam (RSS); (ii) resistance to ampicillin/sulbactam and amoxicillin/clavulanic acid, and susceptibility to piperacillin/tazobactam (RRS); and (iii) resistance to ampicillin/sulbactam, amoxicillin/clavulanic acid and piperacillin/tazobactam (RRR). These resistance patterns are acquired consecutively, indicating a potential risk of developing resistance to piperacillin/tazobactam, but the precise mechanism of this process is not completely understood. METHODS: Clinical isolates incrementally pressured by piperacillin/tazobactam selection in vitro and in vivo were used. We determined the MIC of piperacillin/tazobactam in the presence and absence of piperacillin/tazobactam pressure. We deciphered the role of the blaTEM genes in the new concept of extended-spectrum resistance to BLs/BLIs (ESRI) using genomic analysis. The activity of ß-lactamase was quantified in these isolates. RESULTS: We show that piperacillin/tazobactam resistance is induced in E. coli carrying blaTEM genes. This resistance is due to the increase in copy numbers and transcription levels of the blaTEM gene, thus increasing ß-lactamase activity and consequently increasing piperacillin/tazobactam MICs. Genome sequencing of two blaTEM-carrying representative isolates showed that piperacillin/tazobactam treatment produced two types of duplications of blaTEM (8 and 60 copies, respectively). In the clinical setting, piperacillin/tazobactam treatment of patients infected by E. coli carrying blaTEM is associated with a risk of therapeutic failure. CONCLUSIONS: This study describes for the first time the ESRI in E. coli. This new concept is very important in the understanding of the mechanism involved in the acquisition of resistance to BLs/BLIs.

Exploration of piperazine-derived thioureas as antibacterial and anti-inflammatory agents. In vitro evaluation against clinical isolates of colistin-resistant Acinetobacter baumannii.

A. baumannii is one of the most important multidrug-resistant microorganisms in hospital units. It is resistant to many classes of antibiotics and the development of new therapeutic strategies is necessary. The aim of this study was to evaluate the antibacterial activity of a set of piperazine-derived thioureas against 13 clinical strains of colistin-resistant A. baumannii. Six derivatives were identified to inhibit bacterial growth of 46% of the A. baumannii strains at low micromolar concentrations (Minimum Inhibitory Concentration from 1.56 to 6.25 µM). A common structural feature in most active compounds was the presence of a 3,5-bis-trifluoromethyl phenyl ring at the thiourea function. In addition, the ability of the compounds to inhibit production of nitric oxide (NO) was examined in RAW 264.7 murine macrophages, highlighting the potential of piperazine-derived thioureas as promising scaffolds for the design of new combined anti-bacterial/anti-inflammatory agents.

Prevalence and clinical impact of Streptococcus pneumoniae nasopharyngeal carriage in solid organ transplant recipients.

BACKGROUND: S. pneumoniae is the leading cause of community-acquired pneumonia in the solid organ transplant recipient (SOTR); nevertheless, the prevalence of colonization and of the colonizing/infecting serotypes has not been studied in this population. In this context, the aim of the present study was to describe the rate, characteristics, and clinical impact of S. pneumoniae nasopharyngeal carriage. METHODS: A prospective observational cohort of Solid Organ Transplant recipients (SOTR) was held at the University Hospital Virgen del Rocío, Seville, Spain with the aim to evaluate the S. pneumoniae colonization and the serotype prevalence in SOTR. Two different pharyngeal swabs samples from 500 patients were included in two different seasonal periods winter and spring/summer. Optochin and bile solubility tests were performed for the isolation of thew strains. Antimicrobial susceptibility studies (MICs, mg/l) of levofloxacin, trimethoprim-sulfamethoxazole, penicillin, amoxicillin, cefotaxime, ceftriaxone, erythromycin, azithromycin and vancomycin for each isolate were determined by E-test strips. Capsular typing was done by sequential multiplex PCR reactions. A multivariate logistic regression analysis of factors potentially associated with pneumococcal nasopharyngeal carriage and disease was performed. RESULTS: Twenty-six (5.6%) and fifteen (3.2%) patients were colonized in winter and spring/summer periods, respectively. Colonized SOT recipients compared to non-colonized patients were more frequently men (79.5% vs. 63.1%, P < 0.05) and cohabitated regularly with children (59% vs. 32.2%, P < 0.001). The most prevalent serotype in both studied periods was 35B. Forty-five percent of total isolates were included in the pneumococcal vaccine PPV23. Trimethoprim-sulfamethoxazole and macrolides were the less active antibiotics. Three patients had non-bacteremic pneumococcal pneumonia, and two of them died. CONCLUSIONS: Pneumococcal colonization in SOTR is low with the most colonizing serotypes not included in the pneumococcal vaccines.

Pathogenic Acinetobacter species have a functional type I secretion system and contact-dependent inhibition systems.

Pathogenic Acinetobacter species, including Acinetobacter baumannii and Acinetobacter nosocomialis, are opportunistic human pathogens of increasing relevance worldwide. Although their mechanisms of drug resistance are well studied, the virulence factors that govern Acinetobacter pathogenesis are incompletely characterized. Here we define the complete secretome of A. nosocomialis strain M2 in minimal medium and demonstrate that pathogenic Acinetobacter species produce both a functional type I secretion system (T1SS) and a contact-dependent inhibition (CDI) system. Using bioinformatics, quantitative proteomics, and mutational analyses, we show that Acinetobacter uses its T1SS for exporting two putative T1SS effectors, an Repeats-in-Toxin (RTX)-serralysin-like toxin, and the biofilm-associated protein (Bap). Moreover, we found that mutation of any component of the T1SS system abrogated type VI secretion activity under nutrient-limited conditions, indicating a previously unrecognized cross-talk between these two systems. We also demonstrate that the Acinetobacter T1SS is required for biofilm formation. Last, we show that both A. nosocomialis and A. baumannii produce functioning CDI systems that mediate growth inhibition of sister cells lacking the cognate immunity protein. The Acinetobacter CDI systems are widely distributed across pathogenic Acinetobacter species, with many A. baumannii isolates harboring two distinct CDI systems. Collectively, these data demonstrate the power of differential, quantitative proteomics approaches to study secreted proteins, define the role of previously uncharacterized protein export systems, and observe cross-talk between secretion systems in the pathobiology of medically relevant Acinetobacter species.

Effect of Hypoxia on the Pathogenesis of Acinetobacter baumannii and Pseudomonas aeruginosa In Vitro and in Murine Experimental Models of Infection.

Hypoxia modulates bacterial virulence and the inflammation response through hypoxia-inducible factor 1α (HIF-1α). Here we study the influence of hypoxia on Acinetobacter baumannii and Pseudomonas aeruginosa infections. In vitro, hypoxia increases the bactericidal activities of epithelial cells against A. baumannii and P. aeruginosa, reducing extracellular bacterial concentrations to 50.5% ± 7.5% and 90.8% ± 13.9%, respectively, at 2 h postinfection. The same phenomenon occurs in macrophages (67.6% ± 18.2% for A. baumannii at 2 h and 50.3% ± 10.9% for P. aeruginosa at 24 h). Hypoxia decreases the adherence of A. baumannii to epithelial cells (42.87% ± 8.16% at 2 h) and macrophages (52.0% ± 18.7% at 24 h), as well as that of P. aeruginosa (24.9% ± 4.5% in epithelial cells and 65.7% ± 5.5% in macrophages at 2 h). Moreover, hypoxia decreases the invasion of epithelial cells (48.6% ± 3.8%) and macrophages (8.7% ± 6.9%) by A. baumannii at 24 h postinfection and by P. aeruginosa at 2 h postinfection (75.0% ± 16.3% and 63.4% ± 5.4%, respectively). In vivo, hypoxia diminishes bacterial loads in fluids and tissues in animal models of infection by both pathogens. In contrast, mouse survival time was shorter under hypoxia (23.92 versus 36.42 h) with A. baumannii infection. No differences in the production of cytokines or HIF-1α were found between hypoxia and normoxia in vitro or in vivo We conclude that hypoxia increases the bactericidal activities of host cells against both pathogens and reduces the interaction of pathogens with host cells. Moreover, hypoxia accelerates the rate at which animals die despite the lower bacterial concentrations in vivo.

Peptidoglycan recycling contributes to intrinsic resistance to fosfomycin in Acinetobacter baumannii.

Background: Acinetobacter baumannii is intrinsically resistant to fosfomycin; however, the mechanisms underlying this resistance are poorly understood. Objectives: To identify and characterize genes that contribute to intrinsic fosfomycin resistance in A. baumannii. Methods: More than 9000 individual transposon mutants of the A. baumannii ATCC 17978 strain (fosfomycin MIC ≥1024 mg/L) were screened to identify mutations conferring increased susceptibility to fosfomycin. In-frame deletion mutants were constructed for the identified genes and their susceptibility to fosfomycin was characterized by MIC determination and growth in the presence of fosfomycin. The effects of these mutations on membrane permeability and peptidoglycan integrity were characterized. Susceptibilities to 21 antibiotics were determined for the mutant strains. Results: Screening of the transposon library identified mutants in the ampD and anmK genes, both encoding enzymes of the peptidoglycan recycling pathway, that demonstrated increased susceptibility to fosfomycin. MIC values for in-frame deletion mutants were ≥42-fold (ampD) and ≥8-fold (anmK) lower than those for the parental strain, and growth of the mutant strains in the presence of 32 mg/L fosfomycin was significantly reduced. Neither mutation resulted in increased cell permeability; however, the ampD mutant demonstrated decreased peptidoglycan integrity. Susceptibility to 21 antibiotics was minimally affected by mutations in ampD and anmK. Conclusions: This study demonstrates that AmpD and AnmK of the peptidoglycan recycling pathway contribute to intrinsic fosfomycin resistance in A. baumannii, indicating that inhibitors of these enzymes could be used in combination with fosfomycin as a novel treatment approach for MDR A. baumannii.

Synergistic activity of an OmpA inhibitor and colistin against colistin-resistant Acinetobacter baumannii: mechanistic analysis and in vivo efficacy.

Objectives: Preventing bacterial contact with host cells can provide an additional approach to tackling MDR Acinetobacter baumannii. Recently, we identified AOA-2 as a potential blocker of A. baumannii outer membrane protein A without presenting bactericidal activity. Here, we aimed to study whether AOA-2 can increase the activity of colistin against colistin-resistant A. baumannii in vitro and in vivo. Methods: Reference and clinical A. baumannii strains susceptible and resistant to colistin (CST-S and CST-R) were used. Microdilution and time-kill curve assays were performed to determine the synergy between AOA-2 and colistin. SDS-PAGE assays with CST-S and CST-R outer membrane proteins and MALDI-TOF-TOF (MS-MS/MS) analysis were performed to determine the AOA-2 and colistin synergy mechanism. In a murine peritoneal sepsis model, the therapeutic efficacy of AOA-2 (10 mg/kg/24 h) in combination with a sub-optimal dose of colistin (10 mg/kg/24 h) against CST-R was evaluated by determining the bacterial load in tissues and blood, and mouse survival. Results: We showed that AOA-2 increased the in vitro colistin susceptibility of reference and clinical CST-S and CST-R strains. This combination also enhanced their killing activity after 24 h of drug exposure. This synergy is mediated by the overexpression of Omp25. In vivo, the combination of AOA-2 with colistin significantly reduced the bacterial load in tissues and blood, and increased mouse survival, compared with colistin monotherapy. Conclusions: We identified a novel class of antimicrobial agents that has proven to be effective in combination with colistin in an experimental model of severe infection by CST-R A. baumannii.

Multiple Multicomponent Reactions: Unexplored Substrates, Selective Processes, and Versatile Chemotypes in Biomedicine.

Multiple multicomponent reactions rapidly assemble complex structures. Despite being very productive, the lack of selectivity and the reduced number of viable transformations restrict their general application in synthesis. Hereby, we describe a rationale for a selective version of these processes based in the preferential generation of intermediates which are less reactive than the initial substrates. In this way, applying the Groebke-Blackburn-Bienaymé reaction on a range of α-polyamino-polyazines, we prepared a family compact heterocyclic scaffolds with relevant applications in medicinal and biological chemistry (live cell imaging probes, selective binders for DNA quadruplexes, and antiviral agents against human adenoviruses). The approach has general character and yields complex molecular targets in a selective, tunable and direct manner.

Overproduction of Outer Membrane Protein A by Acinetobacter baumannii as a Risk Factor for Nosocomial Pneumonia, Bacteremia, and Mortality Rate Increase.

Background: Outer membrane protein A (OmpA) is a porin involved in Acinetobacter baumannii pathogenesis. However, OmpA clinical implication in hospital-acquired infections remains unknown. We aimed to determine whether OmpA overproduction was a risk factor associated with pneumonia, bacteremia, and mortality. Methods: We analyzed demographic, microbiological, and clinical data from 100 patients included in a unicenter cohort and 246 included in a unicenter cohort and a multicenter cohort. Representative isolates were classified into 2 groups: (1) isolates from patients colonized by A. baumannii (16 from the unicenter and 20 from the multicenter cohort) and (2) isolates from bacteremic or nonbacteremic patients with pneumonia (PP) caused by A. baumannii (13 from the unicenter and 23 from the multicenter cohort) Expression of ompA was determined with quantitative reverse-transcription polymerase chain reaction. Results: Isolates from PP overexpressed more ompA than those from colonized patients from the unicenter (ratio, 1.76 vs 0.36; P < .001) and the multicenter (1.36 vs 0.91; P = .03) cohorts. Among isolates from PP, those from bacteremic patients overexpressed nonsignificantly more ompA than those from nonbacteremic patients in the unicenter (ratio, 2.37 vs 1.43; P = .06) and the multicenter (2.03 vs 0.91; P = .14) cohorts. Multivariate analysis in both cohorts together showed ompA overexpression as independent risk factor for pneumonia (P < .001), bacteremia (P = .005), and death (P = .049). Conclusions: These data suggest that ompA overexpression is an associated factor for pneumonia, bacteremia, and death due to A. baumannii.

Protective Effects of Human and Mouse Soluble Scavenger-Like CD6 Lymphocyte Receptor in a Lethal Model of Polymicrobial Sepsis.

Sepsis still constitutes an unmet clinical need, which could benefit from novel adjunctive strategies to conventional antibiotic therapy. The soluble form of the scavenger-like human CD6 lymphocyte receptor (shCD6) binds to key pathogenic components from Gram-positive and -negative bacteria and shows time- and dose-dependent efficacy in mouse models of monobacterial sepsis. The objective of the present work was to demonstrate the effectiveness of infusing mouse and human sCD6 by different systemic routes, either alone or as adjunctive therapy to gold standard antibiotics, in a lethal model of polymicrobial sepsis. To this end, C57BL/6 mice undergoing high-grade septic shock induced by cecal ligation and puncture (CLP; ≥90% lethality) were infused via the intraperitoneal (i.p.) or intravenous (i.v.) route with shCD6 at different doses and time points, either alone or in combination with imipenem/cilastatin (I/C) at a dose of 33 mg/kg of body weight every 8 h. Significantly reduced mortality and proinflammatory cytokine levels were observed by i.p. infusion of a single shCD6 dose (1.25 mg/kg) 1 h pre- or post-CLP. When using the i.v. route, mice survival was significantly extended by starting shCD6 infusion at later time points post-CLP (up to 6 h after CLP). Significant adjunctive effects on mouse survival were observed by i.p. or i.v. infusion of shCD6 in combination with i.p. I/C post-CLP. Similar results were obtained in mice expressing high sustained levels (5 to 10 µg/ml) of mouse sCD6 in serum by means of transduction with hepatotropic adeno-associated virus (AAV). Taken together, the data support the conserved antibacterial effects of human and mouse sCD6 and their use as adjunctive therapy in experimental models of complex and severe polymicrobial sepsis.

Optimizing the Clinical Use of Vancomycin.

The increasing number of infections produced by beta-lactam-resistant Gram-positive bacteria and the morbidity secondary to these infections make it necessary to optimize the use of vancomycin. In 2009, the American Society of Health-System Pharmacists, the Infectious Diseases Society of America, and the Society of Infectious Disease Pharmacists published specific guidelines about vancomycin dosage and monitoring. However, these guidelines have not been updated in the past 6 years. This review analyzes the new available information about vancomycin published in recent years regarding pharmacokinetics and pharmacodynamics, serum concentration monitoring, and optimal vancomycin dosing in special situations (obese people, burn patients, renal replacement therapy, among others). Vancomycin efficacy is linked to a correct dosage which should aim to reach an area under the curve (AUC)/MIC ratio of ≥400; serum trough levels of 15 to 20 mg/liter are considered a surrogate marker of an AUC/MIC ratio of ≥400 for a MIC of ≤1 mg/liter. For Staphylococcus aureus strains presenting with a MIC >1 mg/liter, an alternative agent should be considered. Vancomycin doses must be adjusted according to body weight and the plasma trough levels of the drug. Nephrotoxicity has been associated with target vancomycin trough levels above 15 mg/liter. Continuous infusion is an option, especially for patients at high risk of renal impairment or unstable vancomycin clearance. In such cases, vancomycin plasma steady-state level and creatinine monitoring are strongly indicated.

Inhibition of LpxC Increases Antibiotic Susceptibility in Acinetobacter baumannii.

LpxC inhibitors have generally shown poor in vitro activity against Acinetobacter baumannii We show that the LpxC inhibitor PF-5081090 inhibits lipid A biosynthesis, as determined by silver staining and measurements of endotoxin levels, and significantly increases cell permeability. The presence of PF-5081090 at 32 mg/liter increased susceptibility to rifampin, vancomycin, azithromycin, imipenem, and amikacin but had no effect on susceptibility to ciprofloxacin and tigecycline. Potentiating existing antibiotics with LpxC inhibitors may represent an alternative treatment strategy for multidrug-resistant A. baumannii.

Therapeutic efficacy of lysophosphatidylcholine in severe infections caused by Acinetobacter baumannii.

Due to the significant increase in antimicrobial resistance of Acinetobacter baumannii, immune system stimulation to block infection progression may be a therapeutic adjuvant to antimicrobial treatment. Lysophosphatidylcholine (LPC), a major component of phospholipids in eukaryotic cells, is involved in immune cell recruitment and modulation. The aim of this study was to show if LPC could be useful for treating infections caused by A. baumannii. A. baumannii ATCC 17978 was used in this study. Levels of serum LPC and levels of the inflammatory cytokines tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), IL-1ß, and IL-10 were determined by spectrophotometric assay and enzyme-linked immunosorbent assay (ELISA), respectively, using a murine peritoneal sepsis model in which mice were inoculated with 5.3 log CFU/ml of A. baumannii. The therapeutic efficacy of LPC against A. baumannii in murine peritoneal sepsis and pneumonia models was assessed for 48 h after bacterial infection. At early time points in the murine model of peritoneal sepsis caused by A. baumannii, LPC was depleted and was associated with an increase of inflammatory cytokine release. Preemptive therapy with LPC in murine peritoneal sepsis and pneumonia models markedly enhanced spleen and lung bacterial clearance and reduced the numbers of positive blood cultures and the mouse mortality rates. Moreover, treatment with LPC reduced proinflammatory cytokine production. These data demonstrate that LPC is efficacious as a preemptive treatment in experimental models of peritoneal sepsis and pneumonia caused by A. baumannii.