Scientific evidence of the duration of antibiotic treatment in intra-abdominal infections with surgical focus control.

A non-systematic review of the published scientific evidence has been carried out on the duration of empirical antibiotic treatment in surgical intra-abdominal infections (IIA) with effective focus control. Given the progressive increase in antibiotic resistance, it is urgent to have strategies to reduce the pressure on the microbiota. The American guidelines made by Mazuski et al. of 20171, as the central axis in the recommendations of the duration of empirical antibiotic treatment in intra-abdominal infections with control of the focus and a bibliographic search of all the articles that contained the keywords in Pubmed and Google Scholar is added. 21 articles referring to the duration of empirical antibiotic treatment in intra-abdominal infection with control of the focus are collected. With the American guidelines and these articles, a proposal is prepared for the duration of empirical antibiotic treatment in patients without risk factors between 24 and 72 h. And in those who present risk factors, it should be individualized with active monitoring every 24 h of fever, paralytic ileus and leukocytosis (FIL), before an early detection of complications or the need for changes in antibiotic treatment. Short treatments are just as effective as those of longer durations and are associated with fewer adverse effects, therefore, daily adjusting and reassessing the duration of empirical antibiotic treatment is essential for better practice.

Aminoglycoside or Polymyxin Monotherapy for Treating Complicated Urinary Tract Infections Caused by Extensively Drug-Resistant Pseudomonas aeruginosa: A Propensity Score-Adjusted and Matched Cohort Study.

INTRODUCTION: Extensively drug-resistant (XDR) Pseudomonas aeruginosa (PA) infections are difficult to treat. We aimed to compare aminoglycosides or polymyxin monotherapy versus other antibiotic regimens (carbapenems, aztreonam, ceftazidime, cefepime, ceftolozane-tazobactam, or ceftazidime-avibactam) in complicated urinary tract infections (cUTI) caused by XDR-PA. METHODS: Study performed at a tertiary-care hospital from 2010 to 2019. All consecutive adult patients with XDR-PA urine cultures and diagnosed with cUTI were retrospectively reviewed. XDR phenotype was defined according to Magiorakos et al. A propensity score was used as a covariate in multivariate analyses and for matching. Primary outcome was early clinical failure and at end of treatment (EOT). Main secondary outcomes were 30- and 90-day mortality, microbiological clearance, and antibiotic-related side effects. RESULTS: Of the 465 episodes screened, 101 were included, 48% were treated with aminoglycoside or colistin monotherapy. Most XDR-PA were susceptible to colistin (100%) and amikacin (43%). Patients treated with antibiotic regimens other than aminoglycosides or polymyxin monotherapy were more likely to have hematologic malignancy (p < 0.001), higher SOFA score (p = 0.048), and bacteremia (p = 0.003). In multivariate models adjusted by propensity score, aminoglycoside or colistin monotherapy was not associated with worse outcomes. After propensity score matching, 28 episodes in each treatment group were matched. Adjusted ORs (95% CI) for early clinical failure and at EOT with aminoglycosides or polymyxin monotherapy were 0.53 (0.18-1.58) and 1.29 (0.34-4.83), respectively. Aminoglycoside or colistin monotherapy was not associated with higher 30-day (HR 0.93, 95% CI 0.17-5.08) or 90-day mortality (HR 0.68, 95% CI 0.20-2.31), nor with absence of microbiological clearance (OR 0.72, 95% CI 0.33-1.58). No statistically significant differences were found in terms of nephrotoxicity. Clostridioides difficile infection was observed only in the "other antibiotic regimens" group (n = 6, 11.3%). CONCLUSIONS: Aminoglycosides or polymyxin monotherapy showed good efficacy and safety profile in treating cUTI caused by XDR-PA. These results may be useful for antibiotic stewardship activities.

Zinc Differentially Modulates the Assembly of Soluble and Polymerized Vimentin.

The intermediate filament protein vimentin constitutes a critical sensor for electrophilic and oxidative stress. We previously showed that vimentin interacts with zinc, which affects its assembly and redox sensing. Here, we used vimentin wt and C328S, an oxidation-resistant mutant showing improved NaCl-induced polymerization, to assess the impact of zinc on soluble and polymerized vimentin by light scattering and electron microscopy. Zinc acts as a switch, reversibly inducing the formation of vimentin oligomeric species. High zinc concentrations elicit optically-detectable vimentin structures with a characteristic morphology depending on the support. These effects also occur in vimentin C328S, but are not mimicked by magnesium. Treatment of vimentin with micromolar ZnCl2 induces fibril-like particles that do not assemble into filaments, but form aggregates upon subsequent addition of NaCl. In contrast, when added to NaCl-polymerized vimentin, zinc increases the diameter or induces lateral association of vimentin wt filaments. Remarkably, these effects are absent or attenuated in vimentin C328S filaments. Therefore, the zinc-vimentin interaction depends on the chemical environment and on the assembly state of the protein, leading to atypical polymerization of soluble vimentin, likely through electrostatic interactions, or to broadening and lateral association of preformed filaments through mechanisms requiring the cysteine residue. Thus, the impact of zinc on vimentin assembly and redox regulation is envisaged.

Acute Inflammatory Response of Patients with Pseudomonas aeruginosa Infections: A Prospective Study.

The severity of Pseudomonas aeruginosa (PA) infection may be determined by the interaction with the host immune system. We designed a prospective study to assess the relationship between the inflammatory response and the clinical presentation and outcome of PA infection. We also investigated whether there are differences in the inflammatory response depending on the resistance profile of PA. Interleukin-6 (IL-6), IL-10, procalcitonin (PCT), and C-reactive protein (CRP) were measured. Sixty-nine infection episodes were recorded; 40 caused by non-multidrug-resistant (non-MDR) strains [29 (73%) respiratory; 8 (20%) bacteremia], 12 by MDR non-extensively drug-resistant (MDR-non-XDR) [9 (75%) respiratory; 3 (25%) bacteremia], and 17 by XDR strains [9 (53%) respiratory; 7 (41%) bacteremia]. All inflammatory parameters were significantly higher in patients who developed acute organ dysfunction and bacteremia. PCT levels were higher in patients with early mortality [p = 0.050]. Inflammatory biomarkers were higher in patients with XDR than in those with non-MDR PA [IL-6 430 (67-951) vs. 77 (34-216), p = 0.02; IL-10 3.3 (1.5-16.3) vs. 1.3 (0-3.9), p = 0.02; and PCT 1.1 (0.6-5.2) vs. 0.3 (0.1-1.0), p = 0.008]. The intensity of inflammatory response was associated with the severity of PA infection, particularly if bacteremia occurred. Only PCT was documented useful to predict the outcome. XDR infections presented a higher inflammatory response; related in part to the larger number of bloodstream infections in this group.

Understanding the acute inflammatory response to Pseudomonas aeruginosa infection: differences between susceptible and multidrug-resistant strains in a mouse peritonitis model.

The increasing emergence of multidrug-resistant (MDR) Pseudomonas aeruginosa strains is associated with the spread of a few international epidemic clones called high-risk clones. The existence of a fitness cost associated with multidrug resistance remains unclear, and little is known about the host inflammatory response in acute P. aeruginosa infections. This study aimed to investigate how the inflammatory response occurs in the most relevant high-risk clones and to compare the process with that recorded in clinical susceptible isolates. Nine P. aeruginosa strains were studied, including the most relevant MDR high-risk clones (ST111, ST175 and ST235) circulating worldwide. The inflammatory response in terms of the release of interleukins in serum was investigated in a mouse peritonitis-sepsis model at three time points (4, 8 and 12 h). TNFα and interleukin-10 (IL-10) levels were significantly higher at all time points in mice inoculated with clinical susceptible strains compared with those inoculated with MDR strains. IL-6 levels were significantly higher in the clinical susceptible strain group at 8 h and 12 h (P = 0.036 and P = 0.007, respectively). Bacterial counts (log CFU/mL) in peritoneal fluid were higher in the clinical susceptible strain group compared with the MDR strain group at 8 h [6.00 (4.30-6.90) vs. 4.46 (3.30-5.34); P = 0.005] and 12 h [7.75 (4.00-7.97) vs. 4.04 (2.58-4.94); P = 0.003]. MDR P. aeruginosa strains elicited a weaker inflammatory response than susceptible strains in an experimental mouse model, suggesting the existence of a fitness cost associated with multidrug resistance.

Evidence That Bacteriophage λ Kil Peptide Inhibits Bacterial Cell Division by Disrupting FtsZ Protofilaments and Sequestering Protein Subunits.

The effects of Kil peptide from bacteriophage λ on the assembly of Escherichia coli FtsZ into one subunit thick protofilaments were studied using combined biophysical and biochemical methods. Kil peptide has recently been identified as the factor from bacteriophage λ responsible for the inhibition of bacterial cell division during lytic cycle, targeting FtsZ polymerization. Here, we show that this antagonist blocks FtsZ assembly into GTP-dependent protofilaments, producing a wide distribution of smaller oligomers compared with the average size of the intact protofilaments. The shortening of FtsZ protofilaments by Kil is detectable at concentrations of the peptide in the low micromolar range, the mid-point of the inhibition being close to its apparent affinity for GDP-bound FtsZ. This antagonist not only interferes with FtsZ assembly but also reverses the polymerization reaction. The negative regulation by Kil significantly reduces the GTPase activity of FtsZ protofilaments, and FtsZ polymers assembled in guanosine-5'-[(α,ß)-methyleno]triphosphate are considerably less sensitive to Kil. Our results suggest that, at high concentrations, Kil may use an inhibition mechanism involving the sequestration of FtsZ subunits, similar to that described for other inhibitors like the SOS response protein SulA or the moonlighting enzyme OpgH. This mechanism is different from those employed by the division site selection antagonists MinC and SlmA. This work provides new insight into the inhibition of FtsZ assembly by phages, considered potential tools against bacterial infection.

Levetiracetam-induced drug reaction with eosinophilia and systemic symptoms syndrome.

OBJECTIVE: To describe a case of levetiracetam-induced drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome. CASE SUMMARY: A 31-year-old white male with a low-grade astrocytoma presenting with tonic-clonic seizures was treated with levetiracetam 1 g twice daily and dexamethasone (initial dosage 12 mg/day, tapered down to 2 mg/day). On day 45 after levetiracetam initiation, dexamethasone was discontinued and levetiracetam continued. The patient developed fever and dyspnea on day 46 and was admitted to the hospital on day 49. A chest X-ray showed bilateral pulmonary interstitial infiltrates, and laboratory tests showed elevated lactate dehydrogenase (LDH; 288 U/L [reference range <204]), ferritin (223 ng/mL [13-178]), and C-reactive protein (CRP; 3.1 mg/dL [<0.5]). Neurologic fever was suspected and the reinitiation of dexamethasone at 6 mg/day was followed by improvement of all symptoms; the patient was discharged on day 55 with dexamethasone 4 mg/day for 2 more days. On day 59, 2 days after the withdrawal of dexamethasone for the second time, the patient presented with a pruritic erythematous maculopapular rash along with recurrence of fever and dyspnea, and was admitted to the hospital. A chest X-ray showed reappearance of the bilateral pulmonary interstitial infiltrates, and laboratory tests showed impaired liver function (alanine aminotransferase 60 U/L [reference range <56], aspartate aminotransferase 53 U/L [<30], LDH 516 U/L, ferritin 419 ng/mL, and CRP 2.6). A diagnosis of DRESS syndrome was suspected and levetiracetam was discontinued. Upon levetiracetam withdrawal, the patient's symptoms resolved by day 66, and radiological images showed resolution of the interstitial infiltrate by day 68. The patient was discharged on day 68. Low-grade fever persisted until day 71, with no other symptoms. During a 2-month follow-up period, liver function test results returned to normal. DISCUSSION: DRESS is a hypersensitivity reaction to several drugs, mainly antiepileptic drugs (AEDs), characterized by cutaneous, hematologic, and visceral involvement. Levetiracetam is structurally and pharmacologically unrelated to other AEDs. Previously, only one case of levetiracetam-induced DRESS syndrome had been reported, which required corticosteroids to control symptoms. We describe a case of levetiracetam-induced DRESS syndrome presenting with pneumonitis and hepatitis that resolved with levetiracetam withdrawal. Our patient was classified as a definitive DRESS case according to the RegiSCAR scoring system, which grades DRESS cases. According to the Naranjo probability scale, the adverse drug reaction was considered probable. CONCLUSIONS: Although levetiracetam is usually well tolerated, clinicians should be aware of the potential for it to cause DRESS syndrome.

Selective binding of the fluorescent dye 1-anilinonaphthalene-8-sulfonic acid to peroxisome proliferator-activated receptor gamma allows ligand identification and characterization.

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a member of the nuclear receptor superfamily involved in insulin sensitization, atherosclerosis, inflammation, and carcinogenesis. PPARgamma transcriptional activity is modulated by specific ligands that promote conformational changes allowing interaction with coactivators. Here we show that the fluorophore 1-anilinonaphthalene-8-sulfonic acid (ANS) binds to PPARgamma-LBD (ligand binding domain), displaying negligible interaction with other nuclear receptors such as PPARalpha and retinoid X receptor alpha (RXRalpha). ANS binding is competed by PPARgamma agonists such as rosiglitazone, 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)), and 9,10-dihydro-15-deoxy-Delta(12,14)-prostaglandin J(2) (CAY10410). Moreover, the affinity of PPARgamma for these ligands, determined through ANS competition titrations, is within the range of that reported previously, thereby suggesting that ANS competition could be useful in the screening and characterization of novel PPARgamma agonists. In contrast, gel-based competition assays showed limited performance with noncovalently bound ligands. We applied the ANS binding assay to characterize a biotinylated analog of 15d-PGJ(2) that does not activate PPAR in cells. We found that although this compound bound to PPARgamma with low affinity, it failed to promote PPARgamma interaction with a fluorescent SRC-1 peptide, indicating a lack of receptor activation. Therefore, combined approaches using ANS and fluorescent coactivator peptides to monitor PPARgamma binding and interactions may provide valuable strategies to fully understand the role of PPARgamma ligands.

Investigating transcriptional regulation by fluorescence spectroscopy, from traditional methods to state-of-the-art single-molecule approaches.

Gene expression regulation, in particular at the level of transcription, has been demonstrated to play a key role in the development of human diseases, including cancer, and in bacteria it is crucial for proliferation as well as for pathogenicity. Transcriptional regulation is based on complex networks of interactions, including those of the regulatory proteins with the operator DNAs, which are further modulated by ligands. Thus, understanding transcriptional regulation mechanisms requires a thorough analysis of the physical parameters underlying the interactions involved. Among the panoply of methods available, fluorescence spectroscopy-based approaches have been widely used for the assessment of the thermodynamics and structural dynamics of biomolecular interactions. Here we will discuss the application of three fluorescence spectroscopy methods--fluorescence anisotropy and fluorescence correlation and cross-correlation spectroscopy--for the investigation of protein-DNA, protein-protein, and protein-ligand interactions. The weaknesses and the strengths of each method will be highlighted on the basis of our experience in the analysis of the interactions of bacterial repressors implicated in transcriptional regulation in bacilli.