Treatment Of Multidrug-resistant Bacteria Research Articles

A Chemo/photo-responsive immunomodulatory nanoplatform for treatment of multidrug-resistant bacterial sepsis

Multidrug resistant (MDR) bacterial infection has significantly disturbed human health, which may be even fatal in clinical practice. To deal with severe infection induced by MDR bacteria, we have proposed a multifunctional platform on basis of ultrasmall polyethyleneimine (PEI) etched SiC nanodots co-loading with L-arginine (L-Arg) and indocyanine green (ICG). The as-fabricated SiC@PEI-L-Arg/ICG (SPAI) can thoroughly kill MDR bacteria (>99 %) and almost eradicate biofilms through regulating related genetic pathways. This multi-strategy platform integrates potent chemotherapy and near-infrared light-driven NO enhanced auxiliary phototherapy at mild temperature to realize improved antibacterial property. SPAI shows outstanding effect in treatment of MDR bacteria caused skin trauma infection and organic infection (especially sepsis), with satisfactory bactericidal, anti-inflammatory, and immunomodulatory properties in vivo. Owing to excellent biocompatibility, this platform has opened a new avenue for effective treatment of bacterial infectious diseases.

Advances in Engineered Nano-Biosensors for Bacteria Diagnosis and Multidrug Resistance Inhibition.

Bacterial infections continue to pose a significant global health challenge, with the emergence of multidrug-resistant (MDR) bacteria and biofilms further complicating treatment options. The rise of pan-resistant bacteria, coupled with the slow development of new antibiotics, highlights the urgent need for new therapeutic strategies. Nanotechnology-based biosensors offer fast, specific, sensitive, and selective methods for detecting and treating bacteria; hence, it is a promising approach for the diagnosis and treatment of MDR bacteria. Through mechanisms, such as destructive bacterial cell membranes, suppression of efflux pumps, and generation of reactive oxygen species, nanotechnology effectively combats bacterial resistance and biofilms. Nano-biosensors and related technology have demonstrated their importance in bacteria diagnosis and treatment, providing innovative ideas for MDR inhibition. This review focuses on multiple nanotechnology approaches in targeting MDR bacteria and eliminating antimicrobial biofilms, highlighting nano-biosensors via photodynamics-based biosensors, eletrochemistry biosensors, acoustic-dynamics sensors, and so on. Furthermore, the major challenges, opportunities of multi-physical-field biometrics-based biosensors, and relevant nanotechnology in MDR bacterial theranostics are also discussed. Overall, this review provides insights and scientific references to harness the comprehensive and diverse capabilities of nano-biosensors for precise bacteria theranostics and MDR inhibition.

Diadenosine tetraphosphate modulated quorum sensing in bacteria treated with kanamycin

BackgroundThe dinucleotide alarmone diadenosine tetraphosphate (Ap4A), which is found in cells, has been shown to affect the survival of bacteria under stress.ResultsHere, we labeled Ap4A with biotin and incubated the labeled Ap4A with the total proteins extracted from kanamycin-treated Escherichia coli to identify the Ap4A binding protein in bacteria treated with kanamycin. Liquid chromatography‒mass spectrometry (LCMS) and bioinformatics were used to identify novel proteins that Ap4A interacts with that are involved in biofilm formation, quorum sensing, and lipopolysaccharide biosynthesis pathways. Then, we used the apaH knockout strain of E. coli K12-MG1655, which had increased intracellular Ap4A, to demonstrate that Ap4A affected the expression of genes in these three pathways. We also found that the swarming motility of the apaH mutant strain was reduced compared with that of the wild-type strain, and under kanamycin treatment, the biofilm formation of the mutant strain decreased.ConclusionsThese results showed that Ap4A can reduce the survival rate of bacteria treated with kanamycin by regulating quorum sensing (QS). These effects can expand the application of kanamycin combinations in the treatment of multidrug-resistant bacteria.

Nanoparticle therapy for antibiotic-resistant bacteria: current methods and prospects

Emerging diseases due to antibiotic-resistant bacteria cause severe health concerns while increasing their negative effects on human health. The overuse or misuse of antimicrobial agents has contributed to the evolution of bacterial resistance to current medications. Bacteria can develop resistance by altering drugs, changing their target sites, forming biofilms and spending more time in the intracellular environment. Due to this, efforts are being made to create novel, alternative nanoantibiotics as a promising strategy to treat bacteria that cause disease and have developed resistance to a variety of drugs. Utilizing their biocidal properties, nanoparticles can be directed for medication delivery to particular tissues and employed as antibacterial agents against a range of illnesses. Targeted medication delivery-related toxicity problems may be solved with the aid of nanoencapsulation technology. This review paper generally provides a conceptual foundation for understanding the complexity of the problem of the development of antibiotic-resistant bacteria, particularly for brand-new synthetic antibiotics. This information will allow researchers to explore the use of nanoparticles in the treatment of multidrug-resistant bacteria.

Thiol-Based Modification of MarR Protein VnrR Regulates Resistance Toward Nitrofuran in Vibrio cholerae By Promoting the Expression of a Novel Nitroreductase VnrA and of NO-Detoxifying Enzyme HmpA.

Aims: Epidemiological investigations have indicated low resistance toward nitrofuran in clinical isolates, suggesting its potential application in the treatment of multidrug-resistant bacteria. Therefore, it is valuable to explore the mechanism of bacterial resistance to nitrofuran. Results: Through phenotypic screening of ten multiple antibiotic resistance regulator (MarR) proteins in Vibrio cholerae, we discovered that the regulator VnrR (VCA1058) plays a crucial role in defending against nitrofuran, specifically furazolidone (FZ). Our findings demonstrate that VnrR responds to FZ metabolites, such as hydroxylamine, methylglyoxal, hydrogen peroxide (H2O2), β-hydroxyethylhydrazine. Notably, VnrR exhibits reversible responses to the addition of H2O2 through three cysteine residues (Cys180, Cys223, Cys247), leading to the derepression of its upstream gene, vnrA (vca1057). Gene vnrA encodes a novel nitroreductase, which directly contributes to the degradation of FZ. Our study reveals that V. cholerae metabolizes FZ via the vnrR-vnrA system and achieves resistance to FZ with the assistance of the classical reactive oxygen/nitrogen species scavenging pathway. Innovation and Conclusion: This study represents a significant advancement in understanding the antibiotic resistance mechanisms of V. cholerae and other pathogens. Our findings demonstrate that the MarR family regulator, VnrR, responds to the FZ metabolite H2O2, facilitating the degradation and detoxification of this antibiotic in a thiol-dependent manner. These insights not only enrich our knowledge of antibiotic resistance but also provide new perspectives for the control and prevention of multidrug-resistant bacteria.

Antibiotic treatment of community-acquired and hospital-acquired pneumonia

Community-acquired and nosocomial bacterial pneumonia are among the most common infectious diseases in Germany. Knowledge of possible pathogens and therapeutic implications thereof are essential to be able to provide adequate, differentiated antimicrobial therapy with the appropriate drugs, form of application, dose, and duration. New diagnostics that include multiplex polymerase chain reaction, correct interpretation of the biomarker procalcitonin, and treatment of multidrug-resistant bacteria are becoming increasingly import.

Characterization, cytotoxicity, and antibacterial activity of paeoniflorin-loaded mesoporous silica oxide nanoparticles

Multidrug-resistant (MDR) pathogens are emerging as a major health and safety concern worldwide. Nanomaterials and phyto-compounds are become novel antibacterial agents to target MDR pathogens. To increase the efficacy of phyto-compound in the treatment of MDR bacteria, the present work aimed to develop and characterize the paeoniflorin (Pae) loaded silica oxide nanoparticles (Pae-SiO2 NPs). The loading of the Pae on SiO2 NPs and the crystallinity of Pae-SiO2 NPs were determined by FTIR and XRD analysis. The Pae-SiO2 NPs exhibited an average hydrodynamic size of 226 ± 7.79 d. nm and a zeta potential of 28.4 ± 4.59 mV. Furthermore, Pae-SiO2 NPs showed a strong antibacterial effect on Staphylococcus aureus and Bacillus cereus. In addition, Pae-SiO2 NPs showed lowest cytotoxicity and hemolysis in human embryonic kidney 293 cells (HEK 293) and red blood cells (RBC), respectively. Overall, the present results revealed that the Pae-SiO2 NPs exhibited a higher antibacterial activity with lesser toxicity to HEK 293 cells and RBC.

Frontispiece: Recent advances in targeted antibacterial therapy basing on nanomaterials (EXP2 1/2023)

Nanomaterials can assist targeted bacterial depletion in either a passive or active way to enhance inhibitory activity and reduce side effects by increasing local concentration of antibacterial agents. In this review article, we summarize the recent development in the field, which will promote more innovative thinking particularly focusing on the treatment of multidrug resistant bacteria.

Recent advances in targeted antibacterial therapy basing on nanomaterials.

Bacterial infection has become one of the leading causes of death worldwide, particularly in low-income countries. Despite the fact that antibiotics have provided successful management in bacterial infections, the long-term overconsumption and abuse of antibiotics has contributed to the emergence of multidrug resistant bacteria. To address this challenge, nanomaterials with intrinsic antibacterial properties or that serve as drug carriers have been substantially developed as an alternative to fight against bacterial infection. Systematically and deeply understanding the antibacterial mechanisms of nanomaterials is extremely important for designing new therapeutics. Recently, nanomaterials-mediated targeted bacteria depletion in either a passive or active manner is one of the most promising approaches for antibacterial treatment by increasing local concentration around bacterial cells to enhance inhibitory activity and reduce side effects. Passive targeting approach is widely explored by searching nanomaterial-based alternatives to antibiotics, while active targeting strategy relies on biomimetic or biomolecular surface feature that can selectively recognize targeted bacteria. In this review article, we summarize the recent developments in the field of targeted antibacterial therapy based on nanomaterials, which will promote more innovative thinking focusing on the treatment of multidrug-resistant bacteria.

In-vitro anti-bacterial activity of medicinal plants against Urinary Tract Infection (UTI) causing bacteria along with their synergistic effects with commercially available antibiotics

BackgroundPlants contain a variety of bioactive compounds that provide them antimicrobial properties, which can be used to develop novel antibiotics. The current research evaluated the antibacterial activity of 6 medicinal plants Sphagneticola calendulacea (Chinese wedelia), Enydra fluctuans (Buffalo spinach), Chenopodium album (Goosefoot), Mentha arvensis (Wild mint), Mimosa diplotricha (Nila grass), and Averrhoa bilimbi (Cucumber tree) against Urinary Tract Infection (UTI)- causing pathogens (Staphylococcus spp., Proteus spp., Pseudmonas spp., Escherichia coli and Enterobacter spp.). MethodsThe bacterial contamination of these plants was evaluated by using their surface-washed water. The combined effects of commercially available antibiotics along with these medicinal plants were also tested. We used the solvent extraction method, conventional cell culture technique, minimum inhibitory concentration (MIC) assay, and disc diffusion method for our analysis. ResultsThe surface-washed water was contaminated with variable bacteria. The plants displayed notable antibacterial activity against most of the tested bacteria. Ethanol and hot water extract of plants exhibited minimum inhibitory effects, while the methanol extract of plants showed very potent antibacterial activity against most of the bacteria with inhibitory zone diameter up to 14 mm. In the case of combined effects, the zone diameter increased up to 26 mm, which is a significant improvement compared to the individual plant extracts. InterpretationThis data suggested that the combination of two antibacterial agents, one natural and the other synthetic, would be more efficient in the treatment of multidrug-resistant bacteria than a single monotherapy of either of the antibacterial agents.

Multidrug-resistant bacteria: a national challenge requiring urgent addressal

Background: Multidrug-resistant bacterial infections are a worldwide threat owing to their increased prevalence, and poor prognosis due to inadequate antibacterial drugs.Current Concepts: Until 2019, several new antibacterial agents, targeting gram-positive bacteria—including telavancin, oritavancin, dalbavancin, ceftaroline, lefamulin, and delafloxacin—had been approved for use in the United States and Europe. Newer antibiotics targeting gram-negative bacteria include ceftazidime-avibactam, imipenem-cilastatin-relebactam, meropenem-vaborbactam, cefiderocol, eravacycline, and plazomicin. The guidance on the treatment of multidrug-resistant bacteria by the Infectious Diseases Society of America, published in February 2022, recommend the use of new antibacterial agents recently approved. However these drugs have not yet been introduced in Korea, thus impeding their prescription by physicians. Multidrug-resistant bacterial infections demonstrably contribute to a high mortality rate and socioeconomic burden.Discussion and Conclusion: Considering the societal impact of antibiotic resistance, the government should monitor and encourage antimicrobial stewardship to reduce the prevalence of multidrug-resistant bacteria, and hasten the introduction of new antibacterial agents for treating multidrug-resistant bacterial infections in Korea.

Whole-genome analyses of APEC carrying mcr-1 in some coastal areas of China from 2019 to 2020

Polymyxin is considered as one of the 'last lines of defense' for the treatment of multidrug resistant bacteria. Increased use of polymyxin during recent years poses a risk to public health. The purpose of this study was to investigate the carrying situation of the mcr-1 drug-resistance gene in waterfowl in some coastal areas of China from 2019 to 2020. Fifty-seven isolated avian pathogenic Escherichia coli strains were selected from 493 APEC isolates for whole-genome sequencing. The 24 mcr-1-positive APEC strains were tested for conjugation and genome-wide analysis, including sequence type (ST) analysis, serotype analysis, and drug-resistance gene analysis. Numerous mcr-1-positive E. coli were downloaded from the National Center for Biotechnology Information (NCBI) for comparative genomic analysis. Antimicrobial susceptibility test results showed that 57 APEC isolates were highly resistant to gentamicin, cefotaxime, and ofloxacin, and 24 mcr-1-positive APEC isolates were resistant to polymyxin. Fourteen isolates of mcr-1-positive APEC plasmids were successfully conjugated to EC600. Both ST156 and ST10 were found in high proportions in human and avian sources through genome-wide analysis; it is worth noting that these two isolates of APEC were detected to contain the blaNDM-1 and blaNDM-4 genes, respectively. In this study, the epidemiological investigation of the mcr-1 gene was carried out on APEC in some coastal areas of China from 2019 to 2020, and our results have enriched the data on the transmission of APEC isolates carrying the mcr-1 gene in waterfowl.

Treatment of antibiotic-resistant bacteria by nanoparticles: Current approaches and prospects

Antibiotic-resistant bacteria are emerging pathogens whose resistance profiles generate a serious health crisis by holding their impact on human health. Misuse of antibiotics has directed the emergence of microbes immune to presently accessible drugs. Pathogenic bacteria become resistant by employing various mechanisms, such as; antibiotic modification, target site alteration, and biofilm formation, increasing the time they spend in the intracellular environment where antibiotics are unable to succeed at therapeutic levels. Due to this, attempts are being made to develop new alternative nanoantibiotics as a promising approach to treat multidrug resistance disease-causing bacteria. Accordingly, there is considerable contemporary attention to the use of nanoparticles (NPs) as antibacterial agents against different pathogens and as target drug delivery toward specific tissues therefore microbes are eliminated by the biocidal properties of nanoantibiotics. Additionally, the utilization of nanoencapsulation systems can help to beat the issues of, those with toxicity natures, and target drug delivery problems. This review encompasses the antibiotic resistance prevalence, mechanisms, and therefore the use of nanoparticles as antibacterial and drug delivery systems to overcome the antibiotic resistance challenges of bacteria. Overall, this review paper provides a conceptual framework for understanding the complexity of the matter of emergence of antibiotic resistance bacteria even for brand spanking new synthesized antibiotics. Therefore the availability of such knowledge will allow researchers to supply detailed studies about the applications of nanoparticles in the treatment of multidrug-resistant bacteria.

WLBU2 Antimicrobial Peptide as a Potential Therapeutic for Treatment of Resistant Bacterial

Antimicrobial resistance is considered a major health problem, worldwide. It is significantly associated with high morbidity and mortality rates. The current antibiotics have limited therapeutic efficacy in providing treatment for multidrug resistant bacteria. Accordingly, research in the antimicrobial field has been directed toward the discovery of new agents to overcome bacterial resistance. Antimicrobial peptides (AMP) have been extensively studied as potential antimicrobial agents with lower incidence of drug resistance compared to conventional antibiotics. WLBU2 is an engineered cationic AMP with promising antibacterial activity. It is composed of 24 amino acids including; 13 arginine, 8 valine and 3 tryptophan residues. Findings from in vitro and in vivo studies showed that WLBU2 is a potent peptide with a broad spectrum activity against Gram-positive, Gram-negative, multidrug resistant, and biofilm forming bacteria. Additionally, WLBU2 appears as a salt-resistant peptide with potential application for treatment of infections at conditions with disturbed normal salt homeostasis. Furthermore, WLBU2 was found as AMP with limited host toxicity. Recent investigations have shown that combination of WLBU2 with conventional antibiotics can result in synergism against resistant bacteria. In this review we highlight the evidence supporting the promising properties of WLBU2 as an antibacterial agent with potential applications for the treatment of infections caused by resistant bacteria.

Bacteriophages as affordable solution for treatment of multidrug resistant bacteria, and their recent potential applications

The impact of bacteriophages as antibacterial agents was known after their first discovery in 1915, and they were then employed to treat the bacterial infections. However, the discovery of penicillin in 1928 quickly overshadowed bacteriophage therapy, and paved the way for its large-scale production in the 1940s to enter the era of antibiotics. In recent years, resistant bacteria have contributed to increasing the studies on bacteriophages. A remarkable difference between phages and antibiotics is the remarkable phage's specificity to infect certain types of bacteria, which makes them excellent alternatives for treatment of the bacterial infections. Moreover, bacteriophages have different life cycles; knowing the differences between each cycle is essential to exploit the benefits of phages to humans. This review aimed to highlight the history of discovering the bacteriophages and their characteristics; discusses the numerous phages applications including phage therapy, and the limitations of their use.

Isolation and molecular identification of extended spectrum beta-lactamase producing bacteria from urinary tract infection

BackgroundRecent years, the treatment of multi-drug resistant bacteria and their effect are very difficult due to the virulence factors modification. Based on the world wide thread, we have tried to identify the ESBLs producing bacteria from urinary tract infection patients. In result, the highly antibiotic resistant effect of Pseudomonas aeruginosa and Klebsiella pneumoniae were identified. MethodsInitially, Hexa disc diffusion method was performed to detect the multi-drug resistant bacteria using respective antibiotics of HX066, HX033 and HX077, HX012 discs. Consecutively, the ESBL producing ability of confirmed multi drug resistant bacteria was performed to detect their ESBL producing ability using specific extended spectrum beta lactamase (ESBLs) detection discs of Hexa G-minus 24. Furthermore, the ESBL producing ability of the bacteria was confirmed by ESBLs detection Ezy MIC™ E-test stripe method. Results and conclusionsIn result, 10, 5 and 4 mm and 10, 14 and 8 mm zone of inhibition against imipenem (IPM), Ticarcillin/Clavulanic acid (TCC), Cefoperazone (CPZ) and Ampicillin (AMP), Norfloxacin (NX), Nalidixic acid (NA) antibiotics for P. aeruginosa and 16, 22 and 10, 18 mm zone of inhibition against ceftazidime (CAZ), methicillin (MET), ampicillin amoxyclav (AMC), co-trimoxazole (COT) of the HX077 HX012 for K. pneumoniae were observed. Based on the Clinical & Laboratory Standards Institute (CLSI) guidelines, both the bacteria were more resistant to tested antibiotics and it could be developed more resistant against all the tested antibiotics. In addition, the phenotypic detection of ESBL production effect was also performed against both the selected uropathogens, and the results were shown ≥22 mm, ≥27 zone of inhibition against all the tested antibiotics. Further, the genetic identification of multi plux PCR result was shown TEM, SHV and CTX-m genes were present in both the selected uropathogens. Finally, our results were correlated each other and concluded that the selected uropathogens were multi drug resistant effect and also ESBLs producer.

Isolation and identification of specific bacteriophages against methicillin-resistant Staphylococcus aureus, extended-spectrum beta-lactamases-producing Escherichia coli, extended-spectrum beta-lactamases-producing Klebsiella pneumoniae, and multidrug-resistant Acinetobacter baumanniiin vitro.

Drug resistance of methicillin-resistant Staphylococcus aureus, extended-spectrum beta-lactamases-producing Escherichia coli and Klebsiella pneumoniae and multidrug-resistant Acinetobacter baumannii are also cited as one of the most important causes of community and hospital acquired infections. Phage therapy can be used as a therapeutic method for the treatment of infections caused by these bacteria. The aim of this study was to isolate bacteriophages from municipal wastewater and assess their effects against drug resistant bacterial strains. The single agar layer technique was used to investigate the bacteriolytic effect of bacteriophages. Then, the double agar layer technique was used to observe phage plaques and the transmission electron microscopy was used to study the morphology of the bacteriophages. Transparent plaque formation in a double agar layer test of methicillin-resistant S. aureus and extended-spectrum beta-lactamases-producing E. coli and K. pneumoniae indicated the lysis of bacterial cells by isolated bacteriophages. No bacteriophage against A. baumannii was isolated from municipal wastewater. The morphology of these bacteriophages was also identified by electron microscopy. The results of this study showed that bacteriophages act specifically and due to the increasing level of antibiotic resistance, phage therapy as a new treatment can open a new horizon for the treatment of multidrug resistant bacteria.

The GH19 Engineering Database: Sequence diversity, substrate scope, and evolution in glycoside hydrolase family 19.

The glycoside hydrolase 19 (GH19) is a bifunctional family of chitinases and endolysins, which have been studied for the control of plant fungal pests, the recycle of chitin biomass, and the treatment of multi-drug resistant bacteria. The GH19 domain-containing sequences (22,461) were divided into a chitinase and an endolysin subfamily by analyzing sequence networks, guided by taxonomy and the substrate specificity of characterized enzymes. The chitinase subfamily was split into seventeen groups, thus extending the previous classification. The endolysin subfamily is more diverse and consists of thirty-four groups. Despite their sequence diversity, twenty-six residues are conserved in chitinases and endolysins, which can be distinguished by two specific sequence patterns at six and four positions, respectively. Their location outside the catalytic cleft suggests a possible mechanism for substrate specificity that goes beyond the direct interaction with the substrate. The evolution of the GH19 catalytic domain was investigated by large-scale phylogeny. The inferred evolutionary history and putative horizontal gene transfer events differ from previous works. While no clear patterns were detected in endolysins, chitinases varied in sequence length by up to four loop insertions, causing at least eight distinct presence/absence loop combinations. The annotated GH19 sequences and structures are accessible via the GH19 Engineering Database (GH19ED, https://gh19ed.biocatnet.de). The GH19ED has been developed to support the prediction of substrate specificity and the search for novel GH19 enzymes from neglected taxonomic groups or in regions of the sequence space where few sequences have been described yet.

Integration of multiplex PCR and CRISPR-Cas allows highly specific detection of multidrug-resistant Acinetobacter Baumannii

Abstract Bacterial identification and phenotypic antibiotic susceptibility test (p-AST) limit timely anti-infection treatment of patients in clinic to a large extent. Here, we develop a rapid platform integrated multiplex PCR with CRISPR-Cas array to detect multidrug-resistant Acinetobacter baumannii (MDRAB). The platform relies on multiplex PCR amplification strategy which can simultaneously amplify the house-keeping gene and 4 β-lactamase genes of Acinetobacter baumannii (A. baumannii), accompanying with the indiscriminate single-stranded DNase activity of LbaCas12a to generate a single fluorescent signal for multiplex PCR products. The genotypic antibiotic susceptibility test (g-AST) of A. baumannii was completed within 2 h, with a detection limit down to 50 CFU/mL. In addition, we also proved the specificity to differentiate primer dimers. These findings jointly demonstrate the ultimate potential of the CRISPR-Cas12a method for multiple genes detection with high throughput and high specificity. Given the versatility and universality of CRISPR-Cas12a platform, it is expected that this research will further promote its application in the diagnosis and treatment of multidrug-resistant bacteria.

Validation and Application of an HPLC-UV Method for Routine Therapeutic Drug Monitoring of Cefiderocol

Cefiderocol is a new siderophore cephalosporin approved for the treatment of multidrug resistant bacteria including activity against carbapenem-resistant Enterobacterales and Pseudomonas aeruginosa. As cephalosporins are known for their high pharmacokinetic variability in critically ill patients, cefiderocol therapeutic drug monitoring might become a valuable tool. Therefore, we aimed to develop and validate a simple, rapid, cost-effective high performance liquid chromatography (HPLC) method for the quantification of cefiderocol in serum. Samples were treated for protein precipitation followed by chromatographic separation on a reverse phase column (HPLC C-18) with gradient elution of the mobile phase. Cefiderocol was detected via UV absorption and quantification was performed with the internal standard (metronidazole) method. The calibration range showed linearity from 4 to 160 mg/L. The intra and interday precision was less than 10% with a recovery rate of 81%. The method was successfully used for the analysis of subsequent serum samples of critically ill patients and showed good performance in monitoring serum levels and optimizing antibiotic therapy.