Study on antibiotic susceptibility of Salmonella typhimurium L forms to the third and forth generation cephalosporins

Untargeted metabolomics-based identification of bioactive compounds from Mangifera indica L. seed extracts in drug discovery through molecular docking and assessment of their anticancer potential

BACKGROUND

Mangifera indica L. (mango), a medicinal plant rich in biologically active compounds, has potential to be used in disease-preventing and health-promoting products. The present investigation reveals and uncovers bioactive metabolites with remarkable therapeutic efficiency from mango (family: Anacardiaceae) seeds.

RESULTS

Biological activity was determined by antimicrobial, antioxidant and anticancer assays, and metabolite profiling was performed on gas chromatography coupled to quadrupole time-of-flight mass spectrometry (GC-QTOF-MS) and liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) platforms. Validation of active metabolites was carried out by in silico molecular docking (Molinspiration Cheminformatics Server and PASS). Extracted and identified metabolites were screened; 54 compounds associated with various groups were selected for the in silico interaction study.

CONCLUSIONS

Molecular docking revealed lead molecules with a potential binding energy score, efficacy and stable modulation with a selected protein domain. Investigation, directed by in vitro and in silico analysis, confirms mango seeds as an excellent source of potential metabolites as a therapeutic agent. © 2024 Society of Chemical Industry.

Lysozyme Peptides as a Novel Nutra-Preservative to Control Some Food Poisoning and Food Spoilage Microorganisms

Foodborne illnesses and microbial food contamination are crucial concerns and still issues of great worldwide concern. Additionally, the serious health hazards associated with the use of chemical preservatives in food technology. Lysozyme (Lz) is an active protein against Gram-positive bacterial cell wall through its muramidase lytic activity; however, several authors could identify some antimicrobial peptides derived from Lz that have an exaggerated and broad-spectrum antibacterial activity. Therefore, a lysozyme peptides preparation (LzP) is developed to broaden the Lz spectrum. In this work, we investigated the potential efficacy of LzP as a novel Nutra-preservative (food origin) agent against some pathogenic and spoilage bacteria. Our results showed that LzP demonstrated only 11% of the lysozyme lytic activity. However, LzP exhibited strong antibacterial activity against Escherichia coli, Salmonella enteritidis, and Pseudomonas species, while Salmonella typhi and Aeromonas hydrophila exhibited slight resistance. Despite the lowest LzP concentration (0.1%) employed, it performs stronger antibacterial activity than weak organic acids (0.3%). Interestingly, the synergistic multi-component formulation (LzP, glycine, and citric acid) could inhibit 6 log10 cfu/ml of E. coli survival growth. The effect of heat treatment on LzP showed a decrease in its antibacterial activity at 5 and 67% by boiling at 100 °C/30 min, and autoclaving at 121 °C/15 min; respectively. On the other hand, LzP acquired stable antibacterial activity at different pH values (4-7). In conclusion, LzP would be an innovative, natural, and food origin preservative to control the growth of food poisoning and spoilage bacteria in food instead chemical one.

Synthesis of Silver Nanoparticles Using Aggregatimonas sangjinii F202Z8T and Their Biological Characterization

The aim of this study is to describe the general features and eco-friendly biosynthesis of silver nanoparticles (AgNPs) from the marine bacterium Aggregatimonas sangjinii F202Z8T. To the best of our knowledge, no previous study has reported the biosynthesis of AgNPs using this strain. The formation of AgNPs using F202Z8T was synthesized intracellularly without the addition of any disturbing factors, such as antibiotics, nutrient stress, or electron donors. The AgNPs were examined using UV-vis spectrophotometry, transmission electron microscopy, energy-dispersive X-ray spectroscopy, nanoparticle tracking analysis, and Fourier transform infrared spectrometry. The UV-vis spectrum showed a peak for the synthesized AgNPs at 465 nm. The AgNPs were spherical, with sizes ranging from 27 to 82 nm, as denoted by TEM and NTA. FTIR showed various biomolecules including proteins and enzymes that may be involved in the synthesis and stabilization of AgNPs. Notably, the AgNPs demonstrated broad-spectrum antibacterial effects against various pathogenic Gram-positive and Gram-negative bacteria, including Escherichia coli, Bacillus subtilis, and Staphylococcus aureus. The minimum inhibitory concentrations and minimum bactericidal concentrations of the F202Z8T-formed AgNPs were 80 and 100 µg/mL, 40 and 50 µg/mL, and 30 and 40 µg/mL against E. coli, B. subtilis, and S. aureus, respectively. This study suggests that A. sangjinii F202Z8T is a candidate for the efficient synthesis of AgNPs and may be suitable for the formulation of new types of bactericidal substances.

Combined effect of simulated microgravity and low-dose ionizing radiation on structure and antibiotic resistance of a synthetic community model of bacteria isolated from spacecraft assembly room

Understanding the structural and antibiotic resistance changes of microbial communities in space environments is critical for identifying potential pathogens that may pose health risks to astronauts and for preventing and controlling microbial contamination. The research to date on microbes under simulated space factors has primarily been carried out on single bacterial species under the individual effects of microgravity or low-dose radiation. However, microgravity (MG) and low-dose ionizing radiation (LDIR) coexist in the actual spacecraft environment, and microorganisms coexist as communities in the spacecraft environment. Thus, the microbial response to the real changes present during space habitation has not been adequately explored. To address this knowledge gap, we compared the dynamics of community composition and antibiotic resistance of synthetic bacterial communities under simulated microgravit, low-dose ionizing radiation, and the conditions combined, as it occurs in spacecraft. To ensure representative bacteria were selected, we co-cultured of 12 bacterial strains isolated from spacecraft cleanrooms. We found that the weakened competition between communities increased the possibility of species coexistence, community diversity, and homogeneity. The number of Bacilli increased significantly, while different species under the combined conditions showed various changes in abundance compared to those under the individual conditions. The resistance of the synthetic community to penicillins increased significantly under low doses of ionizing radiation but did not change significantly under simulated microgravity or the combined conditions. The results of functional predictions revealed that antibiotic biosynthesis and resistance increased dramatically in the community under space environmental stress, which confirmed the results of the drug sensitivity assays. Our results show that combined space environmental factors exert different effects on the microbial community structure and antibiotic resistance, which provides new insights into our understanding of the mechanisms of evolution of microorganisms in spacecraft, and is relevant to effective microbial pollution prevention and control strategies.

A CcdB toxin-derived peptide acts as a broad-spectrum antibacterial therapeutic in infected mice

The bacterial toxin CcdB (Controller of Cell death or division B) targets DNA Gyrase, an essential bacterial topoisomerase, which is also the molecular target for fluoroquinolones. Here, we present a short cell-penetrating 24-mer peptide, CP1-WT, derived from the Gyrase-binding region of CcdB and examine its effect on growth of Escherichia coli, Salmonella Typhimurium, Staphylococcus aureus and a carbapenem- and tigecycline-resistant strain of Acinetobacter baumannii in both axenic cultures and mouse models of infection. The CP1-WT peptide shows significant improvement over ciprofloxacin in terms of its in vivo therapeutic efficacy in treating established infections of S. Typhimurium, S. aureus and A. baumannii. The molecular mechanism likely involves inhibition of Gyrase or Topoisomerase IV, depending on the strain used. The study validates the CcdB binding site on bacterial DNA Gyrase as a viable and alternative target to the fluoroquinolone binding site.

OXA-48 Carbapenemase-Producing Salmonella typhimurium Nosocomial Bacteremia in the Intensive Care Unit: A Case Report and Review of the Literature

Salmonella enterica serovar Typhimurium is a gram-negative bacterium mainly involved in foodborne diseases. Several pathways of antimicrobial resistance have been recently identified in this strain. This article reports a case of a patient hospitalized in intensive care who underwent emergency trauma surgery. During his hospitalization, he developed a nosocomial bacteremia from a surgical wound infection. The cytobacteriological examination of the surgical site and the blood culture isolated Salmonella spp. susceptible to third-generation cephalosporins, resistant to ertapenem, and with decreased sensitivity to imipenem. The carbapenemase test was positive for blaOXA-48. The serotyping identified Salmonella enterica serovar Typhimurium. The patient's response to antibiotics was favorable.

trans-Cinnamaldehyde as a Novel Candidate to Overcome Bacterial Resistance: An Overview of In Vitro Studies

The increasing of drug-resistant bacteria and the scanty availability of novel effective antibacterial agents represent alarming problems of the modern society, which stimulated researchers to investigate novel strategies to replace or assist synthetic antibiotics. A great deal of attention has been devoted over the years to essential oils that contain mixtures of volatile compounds and have been traditionally exploited as antimicrobial remedies. Among the essential oil phytochemicals, remarkable antimicrobial and antibiotic-potentiating activities have been highlighted for cinnamaldehyde, an α,β-unsaturated aldehyde, particularly abundant in the essential oils of Cinnamomum spp., and widely used as a food additive in industrial products. In line with this evidence, in the present study, an overview of the available literature has been carried out in order to define the bacterial sensitizing profile of cinnamaldehyde. In vitro studies displayed the ability of the substance to resensitize microbial strains to drugs and increase the efficacy of different antibiotics, especially cefotaxime, ciprofloxacin, and gentamicin; however, in vivo, and clinical trials are lacking. Based on the collected findings, cinnamaldehyde appears to be of interest as an adjuvant agent to overcome superbug infections and antibiotic resistance; however, future more in-dept studies and clinical investigations should be encouraged to clarify its efficacy and the mechanisms involved.

Rothia nasimurium as a Cause of Disease: First Isolation from Farmed Chickens

Rothia nasimurium is a facultative anaerobic Gram-positive coccus belonging to the Rothia genus of the Micrococcaceae family. While Rothia nasimurium is considered an opportunistic pathogen, to date few studies have investigated its pathogenicity and drug resistance. In January 2022, chickens at a poultry farm in China's Xinjiang Uygur Autonomous Region became ill and died. Treatment with commonly used Chinese medicines and antibiotics was ineffective, causing economic losses to the poultry farm. In order to determine the cause of the disease in these poultry farm chickens, the isolation and identification of the pathogens in the livers and other internal organs of the sick and dead chickens were performed. Further, animal pathogenicity tests, antibiotic susceptibility tests, and the detection of antibiotic resistance genes were carried out to analyze the pathogenicity and drug resistance of the identified pathogens. A Gram-positive coccus was isolated from the livers of the diseased chickens. The isolate was resistant to 17 antibiotics, including ciprofloxacin, chloramphenicol, and florfenicol, and was only sensitive to penicillin, amikacin, and tigecycline, to varying degrees. The results of the drug resistance gene testing indicated that the isolated bacterium carried 13 kinds of resistance genes. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, morphological observations, biochemical tests, and 16S rRNA gene sequence analysis were performed on the isolated bacterium, and it was determined that the isolated bacterial strain was Rothia nasimurium. The animal pathogenicity tests showed that the isolate caused feather loss and death in chicks; the clinical symptoms and necropsy lesions of the test chicks were consistent with those observed in the farmed chickens. A review of the literature revealed that, to date, there are no reports of infection with Rothia nasimurium in chickens. Thus, in this study, Rothia nasimurium was isolated from chickens for the first time and an investigation of the biological characteristics of the bacterium was carried out in order to provide a reference for the clinical treatment, prevention, and control of Rothia nasimurium infection.

Cell wall deficiency - an alternate bacterial lifestyle?

Historically, many species of bacteria have been reported to produce viable, cell wall deficient (CWD) variants. A variety of terms have been used to refer to CWD bacteria and a plethora of methods described in which to induce, cultivate and propagate them. In this review, we will examine the long history of scientific research on CWD bacteria examining the methods by which CWD bacteria are generated; the requirements for survival in a CWD state; the replicative processes within a CWD state; and the reversion of CWD bacteria into a walled state, or lack thereof. In doing so, we will present evidence that not all CWD variants are alike and that, at least in some cases, CWD variants arise through an adaptive lifestyle switch that enables them to live and thrive without a cell wall, often to avoid antimicrobial activity. Finally, the implications of CWD bacteria in recurring infections, tolerance to antibiotic therapy and antimicrobial resistance will be examined to illustrate the importance of greater understanding of the CWD bacteria in human health and disease.

Macrophage Cell Lines and Murine Infection by Salmonella enterica Serovar Typhi L-Form Bacteria

Antibiotic resistance of pathogenic bacteria has emerged as a major threat to public health worldwide. While stable resistance due to the acquisition of genomic mutations or plasmids carrying antibiotic resistance genes is well established, much less is known about the temporary and reversible resistance induced by antibiotic treatment, such as that due to treatment with bacterial cell wall-inhibiting antibiotics such as ampicillin. Typically, ampicillin concentration in the blood and other tissues gradually increases over time after initiation of the treatment. As a result, the bacterial population is exposed to a concentration gradient of ampicillin during the treatment of infectious diseases. This is different from in vitro drug testing, where the organism is exposed to fixed drug concentrations from the beginning until the end. To mimic the mode of antibiotic exposure of microorganisms within host tissues, we cultured the wild-type, ampicillin-sensitive Salmonella enterica serovar Typhi Ty2 strain (S. Typhi Ty2) in the presence of increasing concentrations of ampicillin over a period of 14 days. This resulted in the development of a strain that displayed several features of the so-called L-form of bacteria, including the absence of the cell wall, altered shape, and lower growth rate compared with the parental form. Studies of the pathogenesis of S. Typhi L-form showed efficient infection of the murine and human macrophage cell lines. More importantly, S. Typhi L-form was also able to establish infection in a mouse model to the extent comparable to its parental form. These results suggested that L-form generation following the initiation of treatment with antibiotics could lead to drug escape of S. Typhi and cell to cell (macrophages) spread of the bacteria, which sustain the infection. Oral infection by the L-form bacteria underscores the potential of rapid disease transmission through the fecal-oral route, highlighting the need for new approaches to decrease the reservoir of infection.

Rothia nasimurium as a Cause of Disease: First Isolation from Farmed Geese

Rothia nasimurium was known previously as an opportunistic pathogen of animals. However, there are few reports regarding the pathogenicity of Rothia nasimurium. In September 2020, geese contracted a disease of unknown cause which brought economic losses to a farm in Jiangsu Province, China, prompting a series of investigations. The bacterium was isolated, cultured, and purified, and then identified using Gram staining, biochemical tests, matrix-assisted laser desorption/ionization time of flight mass spectrometry, and 16S rRNA sequence analysis. After determining the obtained bacteria species, antibiotic susceptibility tests and animal regression experiments were carried out. A strain of bacterium was successfully isolated from the livers of the diseased geese, which was identified as a strain of the Gram-positive bacterium Rothia nasimurium according to the 16S rRNA sequencing results. By indexing references, no goose was reported to have been infected with Rothia nasimurium. The antibiotic susceptibility testing showed that only four antibiotics (amikacin, cefazolin, fosfomycin, and ampicillin/sulbactam) could effectively inhibit the growth of the Rothia nasimurium strain. The animal regression experiments showed that the novel isolated strain could infect goslings, and it also causes serious depilation of goslings. The results of the manuscript expanded the range of pathogenic microorganisms in geese, which is helpful to develop methods for avian endemic control.

Antibiofilm Activity of β-Lactam/β-Lactamase Inhibitor Combination against Multidrug-Resistant Salmonella Typhimurium

This study was designed to assess the effect of β-lactam/β-lactamase inhibitor combinations on the inhibition of biofilm formation of Salmonella Typhimurium. The anti-planktonic and anti-biofilm activities of ampicillin (AMP), ceftriaxone (CEF), and combination treatments of antibiotics and sulbactam (AMP + SUL and CEF + SUL) were evaluated against antibiotic-sensitive S. Typhimurium ATCC 19585 (ST^AS) and clinically isolated multidrug-resistant (MDR) S. Typhimurium CCARM 8009 (ST^MDR). Compared to the control, the minimum inhibitory concentrations (MICs) of AMP against ST^AS and CEF against ST^MDR were decreased from 32 to 16 μg/mL and 0.25 to 0.125 μg/mL, respectively, in the presence of SUL. The numbers of ST^MDR treated with AMP + SUL and CEF + SUL were effectively reduced by more than 2 logs after 4 h of incubation at 37 °C. The β-lactamase activities of ST^AS and ST^MDR treated with AMP and CEF were reduced from 3.3 to 2.6 μmol/min/mL and from 8.3 to 3.4 μmol/min/mL, respectively, in the presence of SUL. The biofilm cell numbers of ST^AS and ST^MDR were reduced at all treatments after 24 h of incubation at 37 °C. The biofilm cell numbers of ST^AS and ST^MDR were reduced by more than 2 logs in the presence of SUL compared to the AMP and CEF alone. The lowest relative fitness level was 0.6 in ST^AS treated with AMP + SUL, while no significant differences in the relative fitness were observed in ST^MDR. This study suggests that β-lactamase inhibitors (BLIs) could be used for controlling biofilm formation of β-lactamase-producing multidrug-resistant S. Typhimurium.

Nanotechnology as a Novel Approach in Combating Microbes Providing an Alternative to Antibiotics

The emergence of infectious diseases promises to be one of the leading mortality factors in the healthcare sector. Although several drugs are available on the market, newly found microorganisms carrying multidrug resistance (MDR) against which existing drugs cannot function effectively, giving rise to escalated antibiotic dosage therapies and the need to develop novel drugs, which require time, money, and manpower. Thus, the exploitation of antimicrobials has led to the production of MDR bacteria, and their prevalence and growth are a major concern. Novel approaches to prevent antimicrobial drug resistance are in practice. Nanotechnology-based innovation provides physicians and patients the opportunity to overcome the crisis of drug resistance. Nanoparticles have promising potential in the healthcare sector. Recently, nanoparticles have been designed to address pathogenic microorganisms. A multitude of processes that can vary with various traits, including size, morphology, electrical charge, and surface coatings, allow researchers to develop novel composite antimicrobial substances for use in different applications performing antimicrobial activities. The antimicrobial activity of inorganic and carbon-based nanoparticles can be applied to various research, medical, and industrial uses in the future and offer a solution to the crisis of antimicrobial resistance to traditional approaches. Metal-based nanoparticles have also been extensively studied for many biomedical applications. In addition to reduced size and selectivity for bacteria, metal-based nanoparticles have proven effective against pathogens listed as a priority, according to the World Health Organization (WHO). Moreover, antimicrobial studies of nanoparticles were carried out not only in vitro but in vivo as well in order to investigate their efficacy. In addition, nanomaterials provide numerous opportunities for infection prevention, diagnosis, treatment, and biofilm control. This study emphasizes the antimicrobial effects of nanoparticles and contrasts nanoparticles' with antibiotics' role in the fight against pathogenic microorganisms. Future prospects revolve around developing new strategies and products to prevent, control, and treat microbial infections in humans and other animals, including viral infections seen in the current pandemic scenarios.

Detection of multidrug-resistant Salmonella enterica subsp. enterica serovar Typhi isolated from Iraqi subjects

Background and Aim

Enteric fever initiated by Salmonella enterica subsp. enterica serovar Typhi (S. Typhi) is among the most consistent disease worldwide, particularly in developing countries. The present study aimed to isolate and identify S. Typhi from typhoid suspected patients and determine their antibacterial susceptibility testing.

Materials and Methods

Thirty blood samples were collected from typhoid suspected patients in Baghdad, Iraq. The samples were cultured on SS agar and XLD agar for screening of S. Typhi. The suspected colonies were picked up and subjected to Vitek 2 compact for biochemical identification and antibacterial susceptibility testing of the organisms. Molecular identification of the isolates was performed by real-time polymerase chain reaction (RT-PCR).

Results

Black colonies were observed on cultured plates. Out of 30 samples, 27 and 29 isolates were identified as S. Typhi using Vitek 2 compact and RT-PCR, respectively. The data of the present study revealed that the strains of S. Typhi were showing multidrug resistance. All S. Typhi strains exhibited resistance to penicillins (ticarcillin and piperacillin), cephalosporins 4^th G (cefepime), and monobactam (aztreonam). However, all the strains showed susceptibility against carbapenems (imipenem and meropenem) and tetracycline (minocycline).

Conclusion

RT-PCR and Vitek 2 compact showed a high level of accuracy in the detection of S. Typhi. Multidrug resistance was observed, which is an alert for the reduction of antibiotic consumption.