The Antimicrobial Effect of Lactoferrin on Gram-Negative and Gram-Positive Bacteria

The revival of fosfomycin

The aim of this study was to increase the antibacterial spectrum of modified hen egg white lysozyme (HEWL) with thermal and chemical treatments against Gram-negative bacteria. The antibacterial activity of heat-denatured HEWL and chemical denatured HEWL against Gram-negative and Gram-positive bacteria was evaluated in 15 h of incubation tests. HEWL was denatured by heating at pH 6.0 and pH 7.0 and chemical denaturing was carried out for 1.0, 1.5, 2.0, and 4.0 h with DL-Dithiothreitol (DTT). HEWL modified by thermal and chemical treatments was characterized using the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) electrophoresis method. Heat-denatured HEWL lytic activity against Micrococcus lysodeikticus lessened with increasing temperature and time of incubation with the chemical agent (DTT). The loss of lytic activity in modified HEWL suggests that the mechanism of action of the antibacterial activity is not dependent on the lytic activity. Thermal and chemical treatments of HEWL enabled the production of oligoforms and increased antibacterial activity over a wider spectrum. Heat-denatured HEWL at pH 6.0 and chemically-denatured HEWL increased the HEWL antibacterial spectrum against Gram-negative bacteria (Escherichia coli ATCC 25922). HEWL at 120 °C and pH 6.0 (1.0 mg/mL) inhibited 78.20% of the growth of E. coli. HEWL/DTT treatment for 4.0 h (1.0 mg/mL) inhibited 68.75% of the growth E. coli. Heat-denatured HEWL at pH 6.0 and pH 7.0 and chemically-denatured HEWL (1.0, 1.5, 2.0, and 4.0 h with DTT) were active against Gram-positive bacteria (Staphylococcus carnosus CECT 4491T). Heat-denatured and chemical-denatured HEWL caused the death of the bacteria with the destruction of the cell wall. LIVE/DEAD assays of fluorescent dye stain of the membrane cell showed membrane perturbation of bacteria after incubation with modified HEWL. The cell wall destruction was viewed using electron microscopy. The results obtained in this study suggest that heat-denatured HEWL at pH 6.0 and chemical-denatured HEWL treatments increase the HEWL antibacterial activity against Gram-negative bacteria.

Kalanchoe pinnata Pers. is one of the famous herbal in Indonesiathat has been used traditionally to treat diarrhea and dysentery. Akinsulire etal., (2007) proved the antibacterial effects of metanolic extract fromKalanchoe pinnata Pers. leaves, and its sensitive to Gram positive andnegative bacteria. Aims of this research are to find out antibacterialactivities of ethyl acetate fraction of methanolic extract from Kalanchoepinnata Pers. leaves to Gram positive bacteria (Staphylococcus aureus,Bacillus subtilis) and Gram negative bacteria (Pseudomonas aeruginosa,Escherichia coli, Salmonella typhi), to determine Minimum InhibitoryConcentration (MIC) of the fraction, and to find out the active chemicalsubstance of the fraction.Methanolic extract of Kalanchoe pinnata Pers. leaves was made byusing maceration method, then the extract was partitioned gradually byusing hexane, chloroform, diethyl ether and ethyl acetate. Ethyl acetatefraction was examinated in vitro according to turbidimetry methods.Concentrations of the fraction were 256, 192, 160, 128, 96, 64, 32 and 16mg/ml. The active chemical substance of the fraction was identified by ThinLayer Chromatography (TLC) method.The result of this research shows the antibacterial activities of ethylacetate fraction of methanolic extract from Kalanchoe pinnata Pers. leavesboth to Gram positive bacteria and Gram negative bacteria. MIC value ofthe fraction to Gram positive bacteria (Staphylococcus aureus, Bacillussubtilis) is 192 mg/ml, and Gram negative bacteria which are Escherichiacoli ATCC 25922 and Pseudomonas aeruginosa is 192 mg/ml, but the MICvalue to Salmonella typhi is 128 mg/ml. TLC identification show that thefraction contains flavonoid. Keywords : Ethyl acetate fraction of methanolic extract from Kalanchoepinnata Pers. leaves, Antibacterial activity, MinimumInhibitory Concentration (MIC), Flavonoid

The COVID-19 pandemic has led to a search for effective pharmaceuticals and vitamins to combat the virus. These therapies have antiviral capabilities and can affect both gram-negative and gram-positive bacteria. This study aims to assess the effectiveness of various medications and nutrients in treating bacterial infections linked to COVID-19. In vitro, tests will be conducted to evaluate these therapies' antibacterial efficacy against both gram-negative and gram-positive bacteria. In the current study, we test a group of antibiotics commonly used in treating Coronavirus on different types of Gram-positive and Gram-negative bacteria. They found that Azithromycin was highly effective against both positive and negative bacteria, but its effectiveness decreased when combined with vitamin D. Levofloxacin was the most effective antibiotic, and its efficacy was not affected by the addition of zinc or vitamin D. Acyclovir had a slight effect on bacteria when used alone, but its efficacy improved with zinc. Zinc and Vitamin D had a high degree of effectiveness, but Vitamin D had relatively low efficacy, except against one type of bacteria. The study aims to evaluate the effectiveness of drugs and vitamins against bacterial infections in COVID-19 patients. The results will provide a better understanding of the potential advantages of these medications in controlling bacterial infections. (The abstract should have one paragraph) The study aims to evaluate the effectiveness of drugs and vitamins against bacterial infections in COVID-19 patients. The results will provide a better understanding of the potential advantages of these medications in controlling bacterial infections.

The antimicrobial quantitative structure-activity relationship of plant flavonoids against Gram-positive bacteria was established in our previous works, and the cell membrane was confirmed as a major site of action. To investigate whether plant flavonoids have similar antibacterial effects and mechanisms against both Gram-negative and Gram-positive bacteria, here, the minimum inhibitory concentrations (MICs) of 37 plant flavonoids against Escherichia coli were determined using the microdilution broth method, and then the correlation between their lipophilic parameter ACD/LogP or LogD7.40 value and their MIC was analyzed. Simultaneously, the correlation between the ACD/LogP or LogD7.40 value and the MIC of 46 plant flavonoids reported in the literature against E. coli was also analyzed. Both sets of results showed that there is a significant correlation between the LogP value and the MIC of plant flavonoids against Gram-negative bacteria. However, it is difficult to effectively predict the MIC of plant flavonoids against Gram-negative bacteria from their lipophilic parameters. By comparing two regression curves derived from plant flavonoids against Gram-negative and Gram-positive bacteria, it was further discovered that the antibacterial activities of most plant flavonoids against Gram-negative bacteria are stronger than those against Gram-positive bacteria when their LogP values are less than approximately 3.0, but the opposite is true when their LogP values are more than approximately 3.6. Moreover, this comparison also suggests that unlike mainly acting on the cell membrane of Gram-positive bacteria, plant flavonoids have multiple mechanisms against Gram-negative species, while the cell membrane is also an important action site among them. Combined with the correlation analyses between the enzyme inhibitory activity and the LogP value of the reported flavonoids, it was further suggested that DNA gyrase is another important target of plant flavonoids against Gram-negative bacteria.

Background: To determine the spectrum of pathogens and their antimicrobial resistance patterns in peritoneal drain fluid samples collected from patients undergoing abdominal surgeries at Lady Reading Hospital. Methods: This’ prospective observational study was conducted from January 2023 to January 2024’ including 73 patients who underwent abdominal surgery with postoperative drain placement. Drain fluid samples were collected under aseptic conditions and subjected to standard culture and sensitivity testing according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Demographic details, surgical characteristics, and resistance trends were analyzed using SPSS version 26, with a p-value <0.05 considered significant. Results: Gram-negative organisms predominated, with Escherichia coli (30.1%) and Klebsiella spp. (20.5%) being the most frequent isolates. Among Gram-positive organisms, Staphylococcus aureus (12.3%) was common, while Candida spp. (8.2%) were the leading fungal isolates. Resistance to ceftriaxone (58.5%) and ciprofloxacin (66.0%) was widespread among Gram-negative bacteria, while carbapenem resistance was observed in nearly one-third of isolates. Vancomycin and linezolid remained highly effective against Gram-positive organisms. Multidrug resistance was most notable in Klebsiella (80%) and Acinetobacter spp. (83.3%). Conclusion: ‘The study highlights a high prevalence of antimicrobial resistance in pathogens isolated from peritoneal drain fluids following abdominal surgery’. The predominance of multidrug-resistant Gram-negative bacteria underscores the urgent need for culture-guided therapy, antimicrobial stewardship, and strict infection control policies in surgical practice.

Scavenger receptor CD36 mediates Staphylococcus aureus phagocytosis and initiates TLR2/6 signaling. We analyzed the role of CD36 in the uptake and TLR-independent signaling of various bacterium, including Escherichia coli, Klebsiella pneumoniae, Salmonella typhimurium, S. aureus, and Enterococcus faecalis. Expression of human CD36 in HeLa cells increased the uptake of both gram-positive and gram-negative bacteria compared with the control mock-transfected cells. Bacterial adhesion was associated with pathogen phagocytosis. Upon CD36 transfection, HEK293 cells, which demonstrate no TLR2/4 expression, acquired LPS responsiveness as assessed by IL-8 production. The cells demonstrated a marked 5- to 15-fold increase in cytokine release upon exposure to gram-negative bacteria, while the increase was much smaller (1.5- to 3-fold) with gram-positive bacteria and lipoteichoic acid. CD36 down-regulation utilizing CD36 small interfering RNA reduced cytokine release by 40-50% in human fibroblasts induced by both gram-negative and gram-positive bacteria as well as LPS. Of all MAPK signaling cascade inhibitors tested, only the inhibitor of JNK, a stress-activated protein kinase, potently blocked E. coli/LPS-stimulated cytokine production. NF-kappaB inhibitors were ineffective, indicating direct TLR-independent signaling. JNK activation was confirmed by Western blot analyses of phosphorylated JKN1/2 products. Synthetic amphipathic peptides with an alpha-helical motif were shown to be efficient inhibitors of E. coli- and LPS-induced IL-8 secretion as well as JNK1/2 activation/phosphorylation in CD36-overexpressing cells. These results indicate that CD36 functions as a phagocytic receptor for a variety of bacteria and mediates signaling induced by gram-negative bacteria and LPS via a JNK-mediated signaling pathway in a TLR2/4-independent manner.

Water microbial purification is one of the hottest topics that threats human morbidity and mortality. It is indispensable to purify water using antimicrobial agents combined with several technologies and systems. Herein, we introduce a class of nanosized metal organic framework; Zeolitic imidazolate framework (ZIF-67) cages encapsulated with polyoxometalates synthesized via facile one-step co-precipitation method. We employed two types of polyoxometalates bioactive agents; phosphotungstic acid (PTA) and phosphomolybdic acid (PMA) that act as novel antibacterial purification agents. Several characterization techniques were utilized to investigate the morphological, structural, chemical, and physical properties such as FESEM, EDS, FTIR, XRD, and N2 adsorption/desorption isotherms techniques. The antibacterial assessment was evaluated using colony forming unit (CFU) against both Escherichia coli and Staphylococcus aureus as models of Gram-negative and Gram-positive bacteria, respectively. The PTA@ZIF-67 showed higher microbial inhibition against both Gram-positive and Gram-negative bacteria by 98.8% and 84.6%, respectively. Furthermore, computational modeling using density functional theory was conducted to evaluate the antibacterial efficacy of PTA when compared to PMA. The computational and experimental findings demonstrate that the fabricated POM@ZIF-67 materials exhibited outstanding bactericidal effect against both Gram-negative and Gram-positive bacteria and effectively purify contaminated water.

Microbial contamination of water poses a major threat to public health. With the emergence of microorganisms resistant to multiple antimicrobial agents, there is increased request for promotion of disinfection methods. Since ultrasound wave (US) exhibits antibacterial activities on bacteria, the aim of this study was to evaluate the antimicrobial effect of low frequency (37 kHz) ultrasound on Pseudomonas aeruginosa and Staphylococcus aureus as a model for gram-negative and gram-positive bacteria, respectively. Sonolysis experiment was carried out in a laboratory-scale batch sonoreactor equipped with plate type transducer at 400 W of acoustic power in the presence and absence of ampicillin as an antibiotic on the both Pseudomonas aeruginosa and Staphylococcus aureus . All of the bacteria were affected by the ultrasound and an increase in percent kill for both bacteria occurred with increasing duration of exposure and intensity of ultrasound. It was found that gram-negative bacteria were more susceptible to the ultrasonic treatment rather than gram-positive bacteria. In addition, the combination of US with an antibiotic (ampicillin) enhanced killing of both bacteria over the use of US alone. The rate of bactericide effect of US wave was increased in samples containing ampicillin. This process was influenced by the chemical and microbiological characteristics of aqueous media. Therefore, with further research about its practicality for treatment of wastewater, it may become a possible substitute process for wastewater disinfection.

Introduction: Antimicrobial Resistance (AMR) is a growing public health threat. Multidrug-resistant (MDR) bacteria, initially associated with healthcare-associated infections, have now spread and become a major cause of community-acquired infections, as well. Therefore, there is a need for monitoring MDR bacterial infections in healthcare settings to establish policies for antimicrobial therapy and effective infection prevention strategies. As pyogenic infections were a major burden of infectious diseases in our healthcare setup, the present study was conducted. Aim: To estimate the prevalence of Multidrug Resistance (MDR) and Extensive Drug Resistance (XDR) in bacterial isolates from pus samples. Materials and Methods: The present hospital-based descriptive cross-sectional study was conducted in the Microbiology Laboratory, SMBT Hospital, Nashik, Maharashtra, India, from June 2022 to May 2023. A total of 360 bacterial isolates from pus samples received from the General Surgery, Orthopaedics and Otorhinolaryngology Departments were tested for antimicrobial susceptibility according to the Clinical and Laboratory Standards Institute (CLSI) 2023 guidelines. Isolates were classified as MDR and XDR as per standard definitions. All Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae) isolates were tested for Ampicillinase C (AmpCs) production by disk approximation test and double disk synergy test. Microsoft Excel 2013 was used for data analysis. Results: The prevalence of MDR and XDR in Gram-negative bacteria was 175 (68.8%) and 120 (47.2%), respectively. The prevalence of MDR and XDR Staphylococcus aureus (S. aureus) was 59 (67%) and 10 (11.3%), respectively. The prevalence of Methicillin Resistant S. aureus (MRSA) was 45.4% (n=40). Out of the total 111 isolates of E. coli and K. pneumoniae, five isolates were AmpC beta-lactamase producers (4.5%). Conclusion: In the present study, a high prevalence of MDR was observed in both Gram-negative and Gram-positive bacteria isolated from different pus samples. This is an alarming situation, and further in-depth studies need to be conducted to assess the association of MDR bacterial infections with particular sites and types of infections to develop effective therapeutic and infection control policies.

In vitro activity of ceftaroline against bacterial isolates causing skin and soft tissue and respiratory tract infections collected in Latin American countries, ATLAS program 2016–2020

Synthesis, antifungal activity and docking study of 2-amino-4H-benzochromene-3-carbonitrile derivatives

To investigate the types of bacteria in patients with eye infections in Suzhou and their drug resistance to commonly used antibacterial drugs. The clinical data of 155 patients were retrospectively collected in this study, and the pathogenic bacteria species and drug resistance of each pathogenic bacteria were analyzed. Among the 155 patients (age from 12 to 87 years old, with an average age of 57, 99 males and 56 females) with eye infections (160 eyes: 74 in the left eye, 76 in the right eye and 5 in both eyes, all of which were exogenous), 71 (45.81%) strains were gram-positive bacteria, 23 (14.84%) strains were gram-negative bacteria and 61 (39.35%) strains were fungi. Gram-positive bacteria were highly resistant to penicillin and erythromycin (78.87% and 46.48% respectively), but least resistant to vancomycin at 0. Gram-negative bacteria were highly resistant to cefoxitin and compound sulfamethoxazole (100% and 95.65% respectively), but least resistant to meropenem at 0. Comparison of the resistance of gram-positive and gram-negative bacteria to some drugs revealed statistically significant differences (P<0.05) in the resistance of both to cefoxitin, cotrimoxazole, levofloxacin, cefuroxime, ceftriaxone and ceftazidime, and both had higher rates of resistance to gram-negative bacteria than to gram-positive bacteria. The distribution of bacterial infection strains showed that Staphylococcus epidermidis was the most common strain in the conjunctiva, cornea, aqueous humor or vitreous body and other eye parts. Besides, Fusarium and Pseudomonas aeruginosa were also among the most common strains of conjunctival and corneal infections. Gram-positive bacteria are the dominant bacteria in eye infections, followed by gram-negative bacteria and fungi. Considering the resistance of gram-negative bacteria to multiple drugs, monitoring of bacteria should be strengthened in eye bacterial infections for effective prevention and control to reduce complications caused by eye infections.

Most bacteria and archaea produce gene-encoded antimicrobial peptides/proteins called bacteriocins, which are secreted by the producing bacteria to compete against other microorganisms in a given niche. They are considered important mediators of intra- and interspecies interactions and therefore a factor in ­maintaining the microbial diversity and stability. They are ribosomally synthesized, and most of them are produced as inactive precursor proteins, which in some cases are further enzymatically modified. Bacteriocins generally exert potent antibacterial activities directed against bacterial species closely related to the producing bacteria. Bacteriocins are abundant and diverse in Gram-negative and Gram-positive bacteria. This chapter focuses on colicins and microcins from enterobacteria (mainly Escherichia coli) and on bacteriocins from lactic acid bacteria (LAB). Microcins are the lower-molecular-mass bacteriocins produced by Gram-negative bacteria with a repertoire of only 14 representatives. They form a very restricted family of bacteriocins, compared to the huge family of LAB bacteriocins that is constituted of several hundreds of peptides, with which microcins share common characteristics. Nevertheless, microcins also show similarities, particularly in their uptake mechanisms, with the higher-molecular-mass colicins, also produced by E. coli strains. On the edge between LAB bacteriocins and colicins, microcins appear to combine highly efficient strategies developed by both Gram-positive and Gram-negative bacteria at different levels, including uptake, translocation, killing of target cells, and immunity of the producing bacteria, making them important actors of bacterial competitions and fascinating models for novel concepts toward antimicrobial strategies and against resistance mechanisms.

Natural additives are a promising tool in modulating rumen fermentation due to the recent concerns regarding microbial resistance to antibiotics. We evaluate the antimicrobial capacity of different levels (10, 20, 50 and 100 mg/L) of monensin, oregano essential oil (Origanum vulgare L), castor oil (Ricinus communis) and Baccharis dracunculifolia (BD) hydroethanolic extract against gram-negative (Prevotella albensis, Prevotella bryantii and Treponema saccharophilum) and gram-positive (Ruminococcus albus, Ruminococcus flavefaciens and Streptococcus bovis) bacteria. Optical density (600 nm) was measured at 8, 12 and 24 h. Monensin inhibited gram-positive bacterial growth (P &lt; 0.05). However, higher dosages were also effective against gram-negative bacteria, possibly due to a toxicological effect. Oregano essential oil inhibited (P &lt; 0.05) both gram-negative and gram-positive bacteria. Castor oil had marginal-to-no effect on gram-negative bacteria, but inhibited the growth of cellulolytic bacteria (Ruminococcus albus) at 12 h. Concentrations of Baccharis dracunculifolia used in this study (up to 100 mg/L) had no inhibitory effect on rumen bacteria. Natural additives are a promising tool to modulate rumen fermentation, which highlights the importance of further studies to evaluate the potential of new products.