LEGO-Lipophosphonoxins: A Novel Approach in Designing Membrane Targeting Antimicrobials.

The alarming rise of bacterial antibiotic resistance requires the development of new compounds. Such compounds, lipophosphonoxins (LPPOs), were previously reported to be active against numerous bacterial species, but serum albumins abolished their activity. Here we describe the synthesis and evaluation of novel antibacterial compounds termed LEGO-LPPOs, loosely based on LPPOs, consisting of a central linker module with two attached connector modules on either side. The connector modules are then decorated with polar and hydrophobic modules. We performed an extensive structure-activity relationship study by varying the length of the linker and hydrophobic modules. The best compounds were active against both Gram-negative and Gram-positive species including multiresistant strains and persisters. LEGO-LPPOs act by first depleting the membrane potential and then creating pores in the cytoplasmic membrane. Importantly, their efficacy is not affected by the presence of serum albumins. Low cytotoxicity and low propensity for resistance development demonstrate their potential for therapeutic use.

Antibiotic treatment issues in patients with COVID-19.

The COVID-19 pandemic may increase the current threat of antimicrobial resistance and exacerbate another, rather silent, pandemic posed by the increasing frequency of multidrug-resistant bacterial pathogens and the associated potential for loss of effective antibiotics. Antibiotic treatment has often been used in patients hospitalized for COVID-19 due to concerns about possible bacterial co-infection, as confirmed by previous experience with viral respiratory infections such as H1N1 influenza, SARS and MERS. Concerns or unknowns related to the COVID-19 pandemic have also affected physicians behavior, including the use of antibiotics. However, the high rate of antibiotic use in patients, especially those with mild to moderate COVID-19 disease, is inconsistent with the actual incidence of bacterial co-infections and/or secondary respiratory infections. Thus, it is clear that a careful assessment of the role of antibiotic treatment in patients hospitalized for COVID-19 is required. According to the current WHO recommendation, the application of antibiotics is especially suitable for patients with severe/critical degree of respiratory insufficiency requiring intensive oxygen therapy, artificial lung ventilation or support by extracorporeal membrane oxygenation.

Detection of Prosthetic Joint Infection Based on Magnetically Assisted Surface Enhanced Raman Spectroscopy.

Accurate and rapid diagnosis of prosthetic joint infection (PJI) is vital for rational and effective therapeutic management of this condition. Several diagnostic strategies have been developed for discriminating between infected and noninfected cases. However, none of them can reliably diagnose the whole spectrum of clinical presentations of PJI. Here, we report a new method for PJI detection based on magnetically assisted surface enhanced Raman spectroscopy (MA-SERS) using streptavidin-modified magnetic nanoparticles (MNP@Strep) whose surface is functionalized with suitable biotinylated antibodies and then coated with silver nanoparticles by self-assembly. The high efficiency of this approach is demonstrated by the diagnosis of infections caused by two bacterial species commonly associated with PJI, namely, Staphylococcus aureus and Streptococcus pyogenes. The method's performance was verified with model samples of bacterial lysates and with four real-matrix samples of knee joint fluid spiked with live pathogenic bacterial cells. This procedure is operationally simple, versatile, inexpensive, and quick to perform, making it a potentially attractive alternative to established diagnostic techniques based on Koch's culturing or colony counting methods.

Occurrence of bacteria producing broad-spectrum beta-lactamases and qnr genes in hospital and urban wastewater samples.

The aims were to investigate the level of antibiotic-resistant bacteria in hospital and urban wastewater and to determine the similarity of isolates obtained from wastewater and hospitalized patients. Wastewater samples were collected in September 2013 and 2014. After identification using MALDI-TOF MS, beta-lactamase production was determined by relevant phenotypic tests. Genes responsible for the production of single beta-lactamase groups and Qnr proteins were established. The epidemiological relationship of the isolates from wastewater and hospitalized patients was determined by PFGE. A total of 51 isolates of enterobacteria were obtained. Overall, 45.1% of them produced broad-spectrum beta-lactamases. Genes encoding TEM, SHV, CTX-M, CIT, DHA and EBC types of enzymes and Qnr proteins were detected. No broad-spectrum beta-lactamase production was confirmed in the urban wastewater treatment plant. The most important finding was the detection of two identical isolates of K. pneumoniae in 2013, one from a patient's urinary catheter and the other from a wastewater sample.

Antibiotic consumption and its influence on the resistance in Enterobacteriaceae.

BACKGROUND: Increasing bacterial resistance to antibiotics is one of the most serious problems in current medicine. An important factor contributing to the growing prevalence of multiresistant bacteria is application of antibiotics. This study aimed at analyzing the development of resistance of Enterobacteriaceae to selected beta-lactam, fluoroquinolone and aminoglycoside antibiotics in the University Hospital Olomouc and assessing the effect of selection pressure of these antibiotics. METHODS: For the period between 1 January 2000 and 31 December 2011, resistance of Klebsiella pneumoniae, Escherichia coli, Enterobacter cloacae and Proteus mirabilis to third- and fourth-generation cephalosporins, meropenem, piperacillin/tazobactam, fluoroquinolones and aminoglycosides was retrospectively studied. For the assessment of selection pressure of antibiotics, a parameter of defined daily dose in absolute annual consumption (DDDatb) based on the ATC/DDD classification and in relative annual consumption (RDDDatb) as the number of defined daily doses per 100 bed-days was used. The relationship between frequency of strains resistant to a particular antibiotic and antibiotic consumption was assessed by linear regression analysis using Spearman's correlation. The level of statistical significance was set at p < 0.05. RESULTS: A total of 113,027 isolates from the Enterobacteriaceae family were analyzed. There was a significant effect of selection pressure of the primary antibiotic in the following cases: piperacillin/tazobactam in Klebsiella pneumoniae, gentamicin in Klebsiella pneumoniae and Escherichia coli and amikacin in Escherichia coli and Enterobacter cloacae. Also, there was significant correlation between resistance to ceftazidime and consumption of piperacillin/tazobactam in Klebsiella pneumoniae and Escherichia coli. No relationship was found between consumption of third- and fourth-generation cephalosporins and resistance to ceftazidime or between fluoroquinolone consumption and resistance to ciprofloxacin. CONCLUSION: The study showed the effects of both direct and indirect selection pressure on increasing resistance to gentamicin, amikacin, piperacillin/tazobactam and ceftazidime. Given the fact that no correlation was found between resistance to fluoroquinolones and consumption of either primary or secondary antibiotics, we assume that the increasing resistance to fluoroquinolones is probably due to circulation of resistance genes in the bacterial population and that this resistance was not affected by reduced use of these antibiotics.

Enterobacter cloacae with a novel variant of ACT AmpC beta-lactamase originating from glaucous gull (Larus hyperboreus) in Svalbard.

We aimed at Escherichia coli and Enterobacter cloacae isolates resistant to cephalosporins and fluoroquinolones and Salmonella isolates in wild birds in Arctic Svalbard, Norway. Cloacal swabs of little auks (Alle alle, n=215) and samples of faeces of glaucous gulls (Larus hyperboreus, n=15) were examined. Inducible production of AmpC enzyme was detected in E. cloacae KW218 isolate. Sequence analysis of the 1146 bp PCR product of the ampC gene from this isolate revealed 99% sequence homology with the blaACT-14 and blaACT-5 AmpC beta-lactamase genes. Four, respectively six of the identified single nucleotide polymorphisms generated amino acid substitutions in the amino acid chain. As the ampC sequence polymorphism in the investigated E. cloacae strain was identified as unique, we revealed a novel variant of the ampC beta-lactamase gene blaACT-23.

Hospital-acquired pneumonia in ICU patients.

BACKGROUND: This prospective study aimed at assessing the effect of initial antibiotic therapy on the mortality of patients with hospital-acquired pneumonia (HAP) by analyzing bacterial pathogens and their resistance to antimicrobial agents. METHODS: Included were patients hospitalized in the Department of Anesthesiology and Intensive Care Medicine, Faculty of Medicine and Dentistry, Palacký University Olomouc and University Hospital Olomouc in 2009 who developed HAP. Bacterial pathogens and their resistance to antibiotics were identified using standard microbiological methods. The patient's mortality with respect to their initial antibiotic therapy was statistically analyzed. RESULTS: The group comprised 51 patients with HAP. Early-onset HAP was identified in 7 (14%) patients and late-onset HAP in 44 (86%) patients. The most frequent bacterial pathogens were strains of Klebsiella pneumoniae, Pseudomonas aeruginosa, Burkholderia cepacia complex and Escherichia coli, together accounting for 72%. Eighteen patients died directly due to HAP, an overall mortality rate of 35%. If initial therapy effective against the bacterial pathogen was selected, 21 patients survived and 9 died. If the bacterial pathogens were resistant to the selected initial antibiotic therapy, 9 patients died and 12 survived. CONCLUSIONS: The mortality rates were 30% and 43% for adequate and inadequate antibiotic therapy, respectively. Given the small group of patients, the difference has low statistical significance. However, it does document the clinical impact of bacterial resistance on the survival or death of patients with HAP.