Agents Of Infections Research Articles

Evolution of mutations in the ftsI gene leading to amino acid substitutions in PBP3 in Haemophilus influenzae strains under the selective pressure of ampicillin and cefuroxime

BackgroundAminopenicillins are recommended agents for non-invasive Haemophilus influenzae infections. One of the mechanisms of resistance to β-lactams is the alteration of the transpeptidase region of penicillin binding protein 3 (PBP3) which is caused by mutations in the ftsI gene. It was shown that exposure to beta-lactams has a stimulating effect on increase of prevalence of H. influenzae strains with the non-enzymatic mechanism of resistance. ObjectivesThe aim of our study was to compare the mutational potential of ampicillin and cefuroxime in H. influenzae strains, determination of minimum inhibitory concentration and the evolution of mutations over time, focusing on amino acid substitutions in PBP3. Methods30 days of serial passaging of strains in liquid broth containing increasing concentrations of ampicillin or cefuroxime was followed by whole-genome sequencing. ResultsOn average, cefuroxime increased the minimum inhibitory concentration more than ampicillin. The minimum inhibitory concentration was increased by a maximum of 32 fold. Substitutions in the PBP3 started to appear after 15 days of passaging. In PBP3, cefuroxime caused different substitutions than ampicillin. ConclusionsOur experiment observed differences in mutation selection by ampicillin and cefuroxime. Selection pressure of antibiotics in vitro generated substitutions that do not occur in clinical strains in the Czech Republic.

Enhanced antibacterial activity of multi-walled carbon nanotubes loaded with hot-melt extruded Mulberry leaf silver nanoparticles

We suggest an antibacterial nanoplatform composed of multi-walled carbon nanotubes (MWCNTs) coated with mesoporous silica decorated with silver nanoparticles (AgNPs) via an N-[3-(trimethoxysilyl)propyl]ethylenediamine (TSD)-mediated method. In this system, the external mesoporous silica shell enhances the dispersion of MWCNTs to increase their contact area with bacterial cell walls. Meanwhile, the multiple mesoporous voids in the silica layer serve as a microreactor for on-site synthesis of small-sized and uniformly distributed AgNPs, thereby enhancing the antibacterial activity. Mulberry leaf (ML) extract was used to reduce Ag ions. In this process, hot melt extrusion (HME) was applied to increase the active ingredients of the ML extract. To prevent loss of ML components due to the heat and pressure applied during HME treatment, several excipients, including whey protein isolate, were mixed, and added. Compared with ML AgNPs and mesoporous silica-coated MWCNTs decorated with AgNPs (MWCNT-Ag), the MWCNT-Ag@ML (MWCNT-ML) exhibited stronger antibacterial against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and methicillin-resistant S. aureus (MRSA). Therefore, this nano platform is a potential antibacterial agent and therapeutic agent for drug-resistant infections.

In vivo efficacy of phage cocktails against carbapenem resistance Acinetobacter baumannii in the rat pneumonia model.

Acinetobacter baumannii, an opportunistic pathogen, poses a significant threat in intensive care units, leading to severe nosocomial infections. The rise of multi-drug-resistant strains, particularly carbapenem-resistant A. baumannii, has created formidable challenges for effective treatment. Given the prolonged development cycle and high costs associated with antibiotics, phages have garnered clinical attention as an alternative for combating infections caused by drug-resistant bacteria. However, the utilization of phage therapy encounters notable challenges, including the narrow host spectrum, where each phage targets a limited subset of bacteria, increasing the risk of phage resistance development. Additionally, uncertainties in immune system dynamics during treatment hinder tailoring symptomatic interventions based on patient-specific states. In this study, we isolated two A. baumannii phages from wastewater and conducted a comprehensive assessment of their potential applications. This evaluation included sequencing analysis, genome classification, pH and temperature stability assessments, and in vitro bacterial inhibition assays. Further investigations involved analyzing histological and cytokine alterations in rats undergoing phage cocktail treatment for pneumonia. The therapeutic efficacy of the phages was validated, and transcriptomic studies of rat lung tissue during phage treatment revealed crucial changes in the immune system. The findings from our study underscore the potential of phages for future development as a treatment strategy and offer compelling evidence regarding immune system dynamics throughout the treatment process.IMPORTANCEDue to the growing problem of multi-drug-resistant bacteria, the use of phages is being considered as an alternative to antibiotics, and the genetic safety and application stability of phages determine the potential of phage application. The absence of drug resistance genes and virulence genes in the phage genome can ensure the safety of phage application, and the fact that phage can remain active in a wide range of temperatures and pH is also necessary for application. In addition, the effect evaluation of preclinical studies is especially important for clinical application. By simulating the immune response situation during the treatment process through mammalian models, the changes in animal immunity can be observed, and the effect of phage therapy can be further evaluated. Our study provides compelling evidence that phages hold promise for further development as therapeutic agents for Acinetobacter baumannii infections.

Prevalence of Hepatozoon canis infection in dogs from the area of Lublin Voivodship

Canine hepatozoonosis is a tick-borne protozoal disease. Two species of Hepatozoon may infect dogs: Hepatozoon americanum and H. canis. The aim of the paper was to attempt to detect the genetic material of H. canis in blood samples collected from dogs suspected to suffer from tick-borne diseases. 107 samples were tested with the use of the real-time PCR technique (Vcheck M Bionote analyser), of which 99 were collected from dogs which never left Polish territory (group 1) and 8 from dogs which spent the holidays with their owners in Turkey (group 2). DNA of H. canis was detected in 1 dog in group 1 (with Ixodes ricinus infestation), and in 2 dogs in group 2 (with Ripicephalus sanguineus infestation). The results obtained indicate that infections with H. canis should be taken into account and included in the differential diagnosis of vector-borne diseases in dogs in Poland, and the accurate identification of the infection agent is crucial for developing the correct treatment regimen and prognosis.

ER-mitochondria association negatively affects wound healing by regulating NLRP3 activation

Methicillin-resistant Staphylococcus aureus (MRSA) is the most common causative agent of acute bacterial skin and skin-structure infections (ABSSSI), one of the major challenges to the health system worldwide. Although the use of antibiotics as the first line of intervention for MRSA-infected wounds is recommended, important side effects could occur, including cytotoxicity or immune dysregulation, thus affecting the repair process. Here, we show that the oxazolidinone antibiotic linezolid (LZD) impairs wound healing by aberrantly increasing interleukin 1 β (IL-1β) production in keratinocytes. Mechanistically, LZD triggers a reactive oxygen species (ROS)-independent mitochondrial damage that culminates in increased tethering between the endoplasmic reticulum (ER) and mitochondria, which in turn activates the NLR family pyrin domain-containing 3 (NLRP3) inflammasome complex by promoting its assembly to the mitochondrial surface. Downregulation of ER-mitochondria contact formation is sufficient to inhibit the LZD-driven NLRP3 inflammasome activation and IL-1β production, restoring wound closure. These results identify the ER-mitochondria association as a key factor for NLRP3 activation and reveal a new mechanism in the regulation of the wound healing process that might be clinically relevant.

Characterization of bacteriophages infecting multidrug-resistant uropathogenic Escherichia coli strains

Uropathogenic Escherichia coli (UPEC) is the most common causative agent of urinary tract infections, and strains that are resistant to antibiotics are a major problem in treating these infections. Phage therapy is a promising alternative approach that can be used to treat infections caused by polyresistant bacterial strains. In the present study, 16 bacteriophages isolated from sewage and surface water were investigated. Phage host specificity was tested on a collection of 77 UPEC strains. The phages infected 2–44 strains, and 80% of the strains were infected by at least one phage. The susceptible E. coli strains belonged predominantly to the B2 phylogenetic group, including strains of two clones, CC131 and CC73, that have a worldwide distribution. All of the phages belonged to class Caudoviricetes and were identified as members of the families Straboviridae, Autographiviridae, and Drexlerviridae and the genera Kagunavirus, Justusliebigvirus, and Murrayvirus. A phage cocktail composed of six phages – four members of the family Straboviridae and two members of the family Autographiviridae – was prepared, and its antibacterial activity was tested in liquid medium. Complete suppression of bacterial growth was observed after 5–22 hours of cultivation, followed by partial regrowth. At 24 hours postinfection, the cocktail suppressed bacterial growth to 43–92% of control values. Similar results were obtained when testing the activity of the phage cocktail in LB and in artificial urine medium. The results indicate that our phage cocktail has potential to inhibit bacterial growth during infection, and they will therefore be preserved in the national phage bank, serving as valuable resources for therapeutic applications.

Ophthalmic Complications, Diagnosis, and Treatment of Congenital Human Cytomegalovirus Infection.

Background: Human cytomegalovirus (hCMV) is the most common etiological agent of congenital infections seen in newborns. Among the most commonly observed complications in children with congenital human cytomegalovirus infection are those affecting the visual system. Ocular complications of congenital CMV (cCMV) are a topic rarely addressed in the literature, which prompted the authors to update the available knowledge with the latest data. Methodology: English-language literature published between April 2000 and November 2023 (PubMed, NIH, Google Scholar) was analyzed for ocular complications of cCMV. The data obtained were categorized according to the ocular area involved and the incidence. A compilation of criteria for the symptomatic form of cCMV was also created. Results: The cCMV complications described in the literature affect all parts of the visual system: the anterior segment, the posterior segment, the posterior visual pathways, and the visual cortex. The most commonly described ocular complication of cCMV is choroidal and retinal scarring. Conclusions: Ophthalmic complications of cCMV can cause severe visual disturbances. Ophthalmic diagnosis in newborns should include hCMV PCR testing, which has the highest sensitivity and specificity. In the symptomatic form of cCMV, treatment should be instituted according to recommendations. A consensus should be established for screening of primary hCMV infection in pregnant women, the way in which to define the symptomatic form of cCMV, and the appropriateness and standards of treatment for primary hCMV infection in pregnant women.

A 14-amino acid cationic peptide Bolespleenin334-347 from the marine fish mudskipper Boleophthalmus pectinirostris exhibiting potent antimicrobial activity and therapeutic potential

Antimicrobial peptides (AMPs) are an important component of innate immunity in both vertebrates and invertebrates, and some of the unique characteristics of AMPs are usually associated with their living environment. The marine fish, mudskipper Boleophthalmus pectinirostris, usually live amphibiously in intertidal environments that are quite different from other fish species, which would be an exceptional source of new AMPs. In the study, an AMP named Bolespleenin334-347 was identified, which was a truncated peptide derived from a new functional gene found in B. pectinirostris, that was up-regulated in response to bacterial challenge. Bolespleenin334-347 had only 14 amino acid residues, including five consecutive arginine residues. It was found that the peptide had broad-spectrum antibacterial activity, good thermal stability and sodium ion tolerance. Bolespleenin334-347 killed Acinetobacter baumannii and Staphylococcus aureus by disrupting the structural integrity of the bacterial membrane, leading to leakage of the cellular contents, and inducing accumulation of bacterial endogenous reactive oxygen species (ROS). In addition, Bolespleenin334-347 effectively inhibited biofilm formation of A. baumannii and S. aureus and long-term treatment did not lead to the development of resistance. Importantly, Bolespleenin334-347 maintained stable activity against clinically multi-drug resistant bacterial strains. In addition, it was noteworthy that Bolespleenin334-347 showed superior efficacy to LL-37 and vancomycin in a constructed mouse model of MRSA-induced superficial skin infections, as evidenced by a significant reduction in bacterial load and more favorable wound healing. This study provides an effective antimicrobial agent for topical skin infections with potential therapeutic efficacy for infections with drug-resistant bacteria, including MRSA.

Antibacterial activity of avocado extract (Persea americana Mill.) against aminoglycoside-resistant Klebsiella pneumoniae strains

Klebsiella pneumoniae is an important etiological agent of nosocomial infections. This study focuses on the antibacterial activity of Persea Americana extract against K. pneumoniae strains containing aminoglycoside genes. Broth microdilution technique was used to examine the antibacterial activity of P. americana extract on K. pneumoniae isolates. The phenolic components of its leaves were analysed by the HPLC-DAD system. The binding potential of the major phytochemical component of the extract, chlorogenic acid, to the KsgA was investigated by molecular docking. The stability of the resulting enzyme-ligand complexes was also assessed through molecular dynamics simulation. The result obtained showed that P. americana extract had antibacterial activity on aminoglycoside resistant strains. The binding potential of chlorogenic acid (main phenolic compound) to KsgA was found to be higher than the binding of gentamicin. Since chlorogenic acid had lower binding energy and formed higher number of H-bonding as well as other interactions in the docking analysis. The higher binding potential of the major component with the enzyme that was involved in resistance development against aminoglycoside indicated its possible role in overturning the condition. Moreover, the molecular dynamics simulation study revealed that chlorogenic acid formed a complex with relatively higher stability. The higher binding potential of the major component with higher stability implied that the computational results confirmed the experimental findings.

Deficiency in non-classical major histocompatibility class II-like molecule, H2-O confers protection against Staphylococcus aureus in mice.

Staphylococcus aureus is a human-adapted pathogen that replicates by asymptomatically colonizing its host. S. aureus is also the causative agent of purulent skin and soft tissue infections as well as bloodstream infections that result in the metastatic seeding of abscess lesions in all organ tissues. Prolonged colonization, infection, disease relapse, and recurrence point to the versatile capacity of S. aureus to bypass innate and adaptive immune defenses as well as the notion that some hosts fail to generate protective immune responses. Here, we find a genetic trait that provides protection against this pathogen. Mice lacking functional H2-O, the equivalent of human HLA-DO, inoculated with a mouse-adapted strain of S. aureus, efficiently decolonize the pathogen. Further, these decolonized animals resist subsequent bloodstream challenge with methicillin-resistant S. aureus. A genetic approach demonstrates that T-cell dependent B cell responses are required to control S. aureus colonization and infection in H2-O-deficient mice. Reduced bacterial burdens in these animals correlate with increased titers and enhanced phagocytic activity of S. aureus-specific antibodies. H2-O negatively regulates the loading of high affinity peptides on major histocompatibility class II (MHC-II) molecules. Thus, we hypothesize that immune responses against S. aureus are derepressed in mice lacking H2-O because more high affinity peptides are presented by MHC-II. We speculate that loss-of-function HLA-DO alleles may similarly control S. aureus replication in humans.

Rapid discrimination methods for clinical and environmental strains of Aeromonas hydrophila and A. veronii biovar sobria using the N-terminal sequence of the flaA gene and investigation of antimicrobial resistance.

Although the genus Aeromonas inhabits the natural environment, it has also been isolated from hospital patient specimens as a causative agent of Aeromonas infections. However, it is not known whether clinical strains live in the natural environment, and if these strains have acquired antimicrobial resistance. In this study, we performed the typing of flagellin A gene (flaA) of clinical and environmental strains of Aeromonas hydrophila and A. veronii biovar sobria using Polymerase Chain Reaction (PCR) assay with newly designed primers. Detection rates of the clinical and environmental flaA types of A. hydrophila were 66.7% and 88.2%, and the corresponding rates for A. veronii biovar sobria were 66.7% and 90.9%. The PCR assays could significantly discriminate between clinical and environmental strains of both species in approximately 4 h. Also, among the 63 clinical Aeromonas strains used, only one extended-spectrum β-lactamase-producing bacteria, no plasmid-mediated quinolone resistance bacteria, and only four multidrug-resistant bacteria were detected. Therefore, the PCR assays could be useful for the rapid diagnosis of these Aeromonas infections and the monitoring of clinical strain invasion into water-related facilities and environments. Also, the frequency of drug-resistant Aeromonas in clinical isolates from Okinawa Prefecture, Japan, appeared to be low.

Epidemiological trends, antifungal drug susceptibility and SQLE point mutations in etiologic species of human dermatophytosis in Al-Diwaneyah, Iraq

Dermatophytes show a wide geographic distribution and are the main causative agents of skin fungal infections in many regions of the world. Recently, their resistance to antifungal drugs has led to an obstacle to effective treatment. To address the lack of dermatophytosis data in Iraq, this study was designed to investigate the distribution and prevalence of dermatophytes in the human population and single point mutations in squalene epoxidase gene (SQLE) of terbinafine resistant isolates. The identification of 102 dermatophytes isolated from clinical human dermatophytosis was performed through morphological and microscopic characteristics followed by molecular analysis based on ITS and TEF-1α sequencing. Phylogeny was achieved through RAxML analysis. CLSI M38-A2 protocol was used to assess antifungal susceptibility of the isolates to four major antifungal drugs. Additionally, the presence of point mutations in SQLE gene, which are responsible for terbinafine resistance was investigated. Tinea corporis was the most prevalent clinical manifestation accounting for 37.24% of examined cases of dermatophytosis. Based on ITS, T. indotineae (50.98%), T. mentagrophytes (19.61%), and M. canis (29.41%) was identified as an etiologic species. T. indotineae and T. mentagrophytes strains were identified as T. interdigitale based on TEF-1α. Terbinafine showed the highest efficacy among the tested antifungal drugs. T. indotineae and T. mentagrophytes showed the highest resistance to antifungal drugs with MICs of 2–4 and 4 μg/mL, while M. canis was the most susceptible species. Three of T. indotineae isolates showed mutations in SQLE gene Phe397Leu substitution. A non-previously described point mutation, Phe311Leu was identified in T. indotineae and mutations Lys276Asn, Phe397Leu and Leu419Phe were diagnosed in T. mentagrophytes XVII. The results of mutation analysis showed that Phe397Leu was a destabilizing mutation; protein stability has decreased with variations in pH, and point mutations affected the interatomic interaction, resulting in bond disruption. These results could help to control the progression of disease effectively and make decisions regarding the selection of appropriate drugs for dermatophyte infections.

Antibiotic resistance pattern of waterborne causative agents of healthcare-associated infections: A call for biofilm control in hospital water systems

BackgroundIn recent years, the global spread of antimicrobial resistance has become a concerning issue, often referred to as a “silent pandemic”. Healthcare-associated infections (HAIs) caused by antibiotic-resistant bacteria (ARB) are a recurring problem, with some originating from waterborne route. The study aimed to investigate the presence of clinically relevant opportunistic bacteria and antibiotic resistance genes (ARGs) in hospital water distribution systems (WDSs). MethodsWater and biofilm samples (n = 192) were collected from nine hospitals in Isfahan and Kashan, located in central Iran, between May 2022 and June 2023. The samples were analyzed to determine the presence and quantities of opportunistic bacteria and ARGs using cultural and molecular methods. ResultsStaphylococcus spp. were highly detected in WDS samples (90 isolates), with 33 % of them harboring mecA gene. However, the occurrences of E. coli (1 isolate), Acinetobacter baumannii (3 isolates), and Pseudomonas aeruginosa (14 isolates) were low. Moreover, several Gram-negative bacteria containing ARGs were identified in the samples, mainly belonging to Stenotrophomonas, Sphingomonas and Brevundimonas genera. Various ARGs, as well as intI1, were found in hospital WDSs (ranging from 14 % to 60 %), with higher occurrences in the biofilm samples. ConclusionOur results underscore the importance of biofilms in water taps as hotspots for the dissemination of opportunistic bacteria and ARG within hospital environments. The identification of multiple opportunistic bacteria and ARGs raises concerns about the potential exposure and acquisition of HAIs, emphasizing the need for proactive measures, particularly in controlling biofilms, to mitigate infection risks in healthcare settings.

Serotype epidemiology and antibiotic resistance of pneumococcal isolates colonizing infants in Botswana (2016-2019).

In 2012, Botswana introduced 13-valent pneumococcal conjugate vaccine (PCV-13) to its childhood immunization program in a 3+0 schedule, achieving coverage rates of above 90% by 2014. In other settings, PCV introduction has been followed by an increase in carriage or disease caused by non-vaccine serotypes, including some serotypes with a high prevalence of antibiotic resistance. We characterized the serotype epidemiology and antibiotic resistance of pneumococcal isolates cultured from nasopharyngeal samples collected from infants (≤12 months) in southeastern Botswana between 2016 and 2019. Capsular serotyping was performed using the Quellung reaction. E-tests were used to determine minimum inhibitory concentrations for common antibiotics. We cultured 264 pneumococcal isolates from samples collected from 150 infants. At the time of sample collection, 81% of infants had received at least one dose of PCV-13 and 53% had completed the three-dose series. PCV-13 serotypes accounted for 27% of isolates, with the most prevalent vaccine serotypes being 19F (n = 20, 8%), 19A (n = 16, 6%), and 6A (n = 10, 4%). The most frequently identified non-vaccine serotypes were 23B (n = 29, 11%), 21 (n = 12, 5%), and 16F (n = 11, 4%). Only three (1%) pneumococcal isolates were resistant to amoxicillin; however, we observed an increasing prevalence of penicillin resistance using the meningitis breakpoint (2016: 41%, 2019: 71%; Cochran-Armitage test for trend, p = 0.0003) and non-susceptibility to trimethoprim-sulfamethoxazole (2016: 55%, 2019: 79%; p = 0.04). Three (1%) isolates were multi-drug resistant. PCV-13 serotypes accounted for a substantial proportion of isolates colonizing infants in Botswana during a four-year period starting four years after vaccine introduction. A low prevalence of amoxicillin resistance supports its continued use as the first-line agent for non-meningeal pneumococcal infections. The observed increase in penicillin resistance at the meningitis breakpoint and the low prevalence of resistance to ceftriaxone supports use of third-generation cephalosporins for empirical treatment of suspected bacterial meningitis.

Bacteriophage cocktail shows no toxicity and improves the survival of Galleria mellonella infected with Klebsiella spp.

Klebsiella spp. are causative agents of healthcare-associated infections in patients who are immunocompromised and use medical devices. The antibiotic resistance crisis has led to an increase in infections caused by these bacteria, which can develop into potentially life-threatening illnesses if not treated swiftly and effectively. Thus, new treatment options for Klebsiella are urgently required. Phage therapy can offer an alternative to ineffective antibiotic treatments for antibiotic-resistant bacteria infections. The aim of the present study was to produce a safe and effective phage cocktail treatment against Klebsiella pneumoniae and Klebsiella oxytoca, both in liquid in vitro culture and an in vivo Galleria mellonella infection model. The phage cocktail was significantly more effective at killing K. pneumoniae and K. oxytoca strains compared with monophage treatments. Preliminary phage cocktail safety was demonstrated through application in the in vivo G. mellonella model: where the phage cocktail induced no toxic side effects in G. mellonella. In addition, the phage cocktail significantly improved the survival of G. mellonella when administered as a prophylactic treatment, compared with controls. In conclusion, our phage cocktail was demonstrated to be safe and effective against Klebsiella spp. in the G. mellonella infection model. This provides a strong case for future treatment for Klebsiella infections, either as an alternative or adjunct to antibiotics.IMPORTANCEKlebsiella infections are a concern in individuals who are immunocompromised and are becoming increasingly difficult to treat with antibiotics due to their drug-resistant properties. Bacteriophage is one potential alternative therapy that could be used to tackle these infections. The present study describes the design of a non-toxic phage cocktail that improved the survival of Galleria mellonella infected with Klebsiella. This phage cocktail demonstrates potential for the safe and effective treatment of Klebsiella infections, as an adjunct or alternative to antibiotics.

<i>Stenotrophomonas maltophilia</i> as a causative agent of implant-associated infection in trauma and orthopedic patients

Objective. To evaluate an etiologic significance of S. maltophilia in the development of orthopedic implant-associated infections. Materials and methods. The study involved a retrospective analysis of the frequency of excretion of S. maltophilia in patients with periprosthetic infection and osteomyelitis, using the Microbe-2 program in period of 2005–2020. Clinical isolates were excreted according to standard methods. Identification was performed via Microlatest panels using iEMS Reader MF. Antibiotic susceptibility was studied in accordance with EUCAST. Results. Over 16 years 69 strains of S. maltophilia have been identified, comprising 0.33% of all isolated pathogens (n=20631). 50% of isolates were excreted from tissue biopsies, 30% – from wound exudates. In 89% of cases, S. maltophilia was isolated in microbial associations, including 65% of cases together with Grampositive bacteria, 18% with other non-fermenting Gram-negative bacteria, and 6% with other pathogens. 63% appeared sensitive to trimethoprim/sulfamethoxazole and 25.5% of isolates were resistant. The proportion of cultures sensitive to this drug was found to increase from 63% in 2011–2014 to 81% in 2015–2019 (p = 0.08). Conclusion. S. maltophilia should be considered as a causative etiologic agent of severe chronic orthopedic infections.

The role of aztreonam in rational antibacterial therapy of resistant nosocomial gram-negative infections. The new life for a well-known β-lactam

Background. The situation regarding the prevalence of resistant pathogens, types of β-lactamase products, and, accordingly, the justification of rational approaches to antibacterial therapy in Ukraine remains insufficiently studied. Objective: based on the determination of the etiological structure of the causative agents of hospital infections in the Kharkiv region and the state of their resistance due to the production of β-lactamases, to propose rational approaches to antibacterial therapy and assess the feasibility of using aztreonam as a potentially effective mean of treating infections caused by resistant bacteria. Materials and methods. In 251 patients, samples of biomaterials were tested by the polymerase chain reaction for the presence of the following gram-negative pathogens: P.aeruginosa, Enterobacter, E.coli, K.pneumoniae, Proteus spp. and A.baumanii. A molecular genetic study was also conducted to identify certain types of β-lactamases. Results. In the structure of hospital pathogens, the absolute majority of gram-negative bacteria belong to the enterobacteria family. When determining the profile of β-lactamases, we found that in 59.38 % of cases, E.coli was able to produce metallo-β-lactamases, which makes the therapy with carbapenems or ceftazidime-avibactam impossible. An alternative in such cases is a combination of aztreonam and ceftazidime-avibactam. When the causative agent K.pneumoniae is detected, in some cases there may also be a need for combined therapy with the use of aztreonam. It was found that Enterobacter spp. in most cases is sensitive to carbapenems. A.baumanii is completely insensitive to carbapenems and requires alternative approaches to antibacterial therapy, including aztreonam, ceftazidime-avibactam, and polymyxins. P.aeruginosa was found only as part of polymicrobial associations, so it was impossible to analyze its β-lactamase production profile. Conclusions. The results of the conducted study demonstrate an extremely high detection of gram-negative antibiotic-resistant pathogens in patients of the intensive care units in the Kharkiv region. Microorganisms such as E.coli and A.baumanii have the most unfavorable profile of antibiotic resistance, which is due to the high frequency of production of serine carbapenemases and metallo-β-lactamases, whose presence makes the effective use of carbapenems impossible.

A membrane-targeting magnolol derivative for the treatment of methicillin-resistant Staphylococcus aureus infections.

Multidrug-resistant bacterial infections are a major global health challenge, especially the emergence and rapid spread of methicillin-resistant Staphylococcus aureus (MRSA) urgently require alternative treatment options. Our study has identified that a magnolol derivative 6i as a promising agent with significant antibacterial activity against S. aureus and clinical MRSA isolates (MIC = 2-8 μg/mL), showing high membrane selectivity. Unlike traditional antibiotics, 6i demonstrated rapid bactericidal efficiency and a lower propensity for inducing bacterial resistance. Compound 6i also could inhibit biofilm formation and eradicate bacteria within biofilms. Mechanistic studies further revealed that 6i could target bacterial cell membranes, disrupting the integrity of the cell membrane and leading to increased DNA leakage, resulting in potent antibacterial effects. Meanwhile, 6i also showed good plasma stability and excellent biosafety. Notably, 6i displayed good in vivo antibacterial activity in a mouse skin abscess model of MRSA-16 infection, which was comparable to the positive control vancomycin. These findings indicated that the magnolol derivative 6i possessed the potential to be a novel anti-MRSA infection agent.

Genomic Characterization of Carbapenemase-Producing Enterobacter hormaechei, Serratia marcescens, Citrobacter freundii, Providencia stuartii, and Morganella morganii Clinical Isolates from Bulgaria.

Carbapenemase-producing Enterobacter spp. Serratia marcescens, Citrobacter freundii, Providencia spp., and Morganella morganii (CP-ESCPM) are increasingly identified as causative agents of nosocomial infections but are still not under systematic genomic surveillance. In this study, using a combination of whole-genome sequencing and conjugation experiments, we sought to elucidate the genomic characteristics and transferability of resistance genes in clinical CP-ESCPM isolates from Bulgaria. Among the 36 sequenced isolates, NDM-1 (12/36), VIM-4 (11/36), VIM-86 (8/36), and OXA-48 (7/36) carbapenemases were identified; two isolates carried both NDM-1 and VIM-86. The majority of carbapenemase genes were found on self-conjugative plasmids. IncL plasmids were responsible for the spread of OXA-48 among E. hormaechei, C. freundii, and S. marcescens. IncM2 plasmids were generally associated with the spread of NDM-1 in C. freundii and S. marcescens, and also of VIM-4 in C. freundii. IncC plasmids were involved in the spread of the recently described VIM-86 in P. stuartii isolates. IncC plasmids carrying blaNDM-1 and blaVIM-86 were observed too. blaNDM-1 was also detected on IncX3 in S. marcescens and on IncT plasmid in M. morganii. The significant resistance transfer rates we observed highlight the role of the ESCPM group as a reservoir of resistance determinants and stress the need for strengthening infection control measures.

Bacteriological Study of Post-Operative Wound Infection and its Antibiograms

INTRODUCTIONPostoperative wound infections are a significant complication of surgical procedures, which increases morbidity, mortality, prolonged hospital stay, and increased healthcare costs. The study was undertaken with an aim to investigate the etiological agents of postoperative wounds and their sensitivity to commonly used antibiotics. MATERIAL AND METHODSThis study was a descriptive cross-sectional prospective study, carried out at Universal College Of Medical Sciences-Teaching Hospital, Bhairahawa, Nepal, on 100 postoperatively wounded infected cases, during April 2023 – August 2023, Non Probability sampling method (Purposive sampling) was used, and specimens were collected by sterile cotton swabs and pus was aspirated with a sterile needle and syringe and processed using standard bacteriological techniques. Antibiotic sensitivity test was conducted by disc diffusion (Kirby-Bauer) method. RESULTSPostoperative wound infections caused by Gram negative bacilli were more frequent and predominant pathogens involved were Pseudomonas aeruginosa, followed by Klebsiella spp and Enterobacter aerogenes. Among Gram positive bacteria Staphylococcus aureus was predominant. Gram positive cocci were highly sensitive to Ampicillin, and Gram negative bacilli were highly sensitive to Ceftazidime, Gentamicin, and Amikacin. Coagulase negative staphylococci were resistant to all drugs tested. CONCLUSIONPseudomonas aeruginosa was the commonest etiological agent for postoperative wound infections. Gram positive cocci and E.coli were highly sensitive to Ampicillin and Gram negative bacilli were highly sensitive to Ceftazidime, Gentamicin, Amikacin. Staphylococcus aureus was resistant to vancomycin and Teicoplanin and coagulase staphylococci were resistant to all drugs tested. Gram negative bacilli were resistant to Polymyxin B and Tigecycline. Increasing resistance to commonly used antibiotics warrants the judicious use of antibiotics and establishment of antibiotic policy in the hospital.