Emergence Of Resistant Bacteria Research Articles

Global Impact of Antibiotic Resistance

Antibiotic resistance (AMR) is a growing global health crisis that poses a significant threat to public health, economies, and healthcare systems worldwide. The emergence of resistant bacteria, fungi, and viruses has been driven by the overuse and misuse of antibiotics in human medicine, agriculture, and animal farming. AMR reduces the effectiveness of treatment options, leading to longer hospital stays, increased medical costs, and higher mortality rates. Furthermore, infections caused by resistant pathogens are becoming harder to treat, complicating efforts to combat common diseases such as pneumonia, tuberculosis, and urinary tract infections. The global impact of antibiotic resistance is not limited to individual countries; it is a cross-border issue that requires international cooperation and a multifaceted approach, involving surveillance, regulation, and public awareness campaigns. Low- and middle-income countries, where access to antibiotics is often unregulated, face the highest risks. In addition to human health, the economic toll of AMR is severe, with global estimates suggesting that antibiotic resistance could lead to a reduction in global GDP by up to 3.5% by 2050. Combating AMR requires urgent action from governments, healthcare providers, pharmaceutical companies, and the public to implement better stewardship practices, invest in research and development of new antibiotics, and adopt preventative measures. A united global response is essential to mitigate the long-term consequences of this silent pandemic.

Decoding the trajectory of antibiotic resistance genes in saline and alkaline soils: Insights from different fertilization regimes.

The soil salinity and alkalinity play an important role in the occurrence and proliferation of antibiotic resistance genes (ARGs). Yet, little is known the underlying mechanism by which soil salinity and alkalinity affect antibiotic resistance evolution. Here we investigated the ARGs variation in soil salinity and alkalinity environments created by different fertilization, and explored the biological mechanisms that salinity and alkalinity alter the evolutionary paradigm of antibiotic resistance. The results showed the soil treated by organic fertilizer exhibited a low salinity, neutral level (TSD 239.20 μS/cm, pH 7.17). The ARG abundance in the OF treatment was the highest, keeping an average of 67.83 TPM. Beside the effect of direct input of organic fertilizer at the beginning, it was important to note that, ARGs abundance during planting showed significant correlations with pH and electric conductivity. We observed that changes in microbial survival strategies under different salinity and alkalinity conditions further affected ARG hosts abundance. Indoor experiments demonstrated that there was a survival trade-off between the growth of resistant bacteria and the evolution of antibiotic resistance in salinity and alkalinity environments. Meta-genomic and Meta-transcriptomic analysis consistently demonstrated bacterial antibiotic resistance was primarily associated with pyruvate, energy and lipid metabolic pathways. The functional gene related to salinity and alkalinity, like cysH, cysK, plsB and plsC showed negative correlations with MDR. Prokaryotic transcription assays validated these relations. This study well explains the prevalence of soil ARGs after different fertilization regimes and will give a deeper understanding for the effect of soil salinity and alkalinity on antibiotic resistance evolution.

From Challenges to Solution: The Evolving Landscape of Leprosy Management

AbstractLeprosy, caused by Mycobacterium leprae, despite being a curable disease when treated can induce peripheral neuropathy. However, the medicines used in polychemotherapy promote several side effects. Thus, research for the development of new administration systems is an alternative, but there is a lack of preclinical and clinical studies of the systems, where 90.90% have a level of technological maturity 3 and 9.09% level 4. The main issues are associated with deficiencies in vitro and in vivo cultivation methodologies, lack of financing, as well as the disinterest of the pharmaceutical industry in investing in neglected tropical diseases. In addition, with the emergence of resistant bacteria, there is urgency in the search for vaccines and, therefore, in the expansion of immunomodulation studies to define the molecular targets of the vaccine and future medications. In addition, future treatments for various diseases, including leprosy, will be directly influenced by the evolution of additive manufacturing and 3D printing, seeking personalized, flexible, and reproducible treatment.

Peptide-mimetic treatment of Pseudomonas aeruginosa in a mouse model of respiratory infection

The rise of drug resistance has become a global crisis, with >1 million deaths due to resistant bacterial infections each year. Pseudomonas aeruginosa, in particular, remains a serious problem with limited solutions due to complex resistance mechanisms that now lead to more than 32,000 multidrug-resistant (MDR) infections and over 2000 deaths in the U.S. annually. While the emergence of resistant bacteria has become ominously common, identification of useful new drug classes has been limited over the past over 40 years. We found that a potential novel therapeutic, the peptide-mimetic TM5, is effective at killing P. aeruginosa and displays sufficiently low toxicity in mammalian cells to allow for use in treatment of infections. Interestingly, TM5 kills P. aeruginosa more rapidly than traditional antibiotics, within 30–60 min in vitro, and is effective against a range of clinical isolates, including extensively drug resistant strains. In vivo, TM5 significantly reduced bacterial load in the lungs within 24 h compared to untreated mice and demonstrated few adverse effects. Taken together, these observations suggest that TM5 shows promise as an alternative therapy for MDR P. aeruginosa respiratory infections.

Conserved Evolutionary Trajectory Can Be Perturbed to Prevent Resistance Evolution under Norfloxacin Pressure by Forcing Mycobacterium smegmatis on Alternate Evolutionary Paths.

Antibiotic resistance is a pressing health issue, with the emergence of resistance in bacteria outcompeting the discovery of novel drug candidates. While many studies have used Adaptive Laboratory Evolution (ALE) to understand the determinants of resistance, the influence of the drug dosing profile on the evolutionary trajectory remains understudied. In this study, we employed ALE on Mycobacterium smegmatis exposed to various concentrations of Norfloxacin using both cyclic constant and stepwise increasing drug dosages to examine their impact on the resistance mechanisms selected. Mutations in an efflux pump regulator, LfrR, were found in all of the evolved populations irrespective of the drug profile and population bottleneck, indicating a conserved efflux-based resistance mechanism. This mutation appeared early in the evolutionary trajectory, providing low-level resistance when present alone, with a further increase in resistance resulting from successive accumulation of other mutations. Notably, drug target mutations, similar to those observed in clinical isolates, were only seen above a threshold of greater than 4× the minimum inhibitory concentration (MIC). A combination of three mutations in the genes, lfrR, MSMEG_1959, and MSMEG_5045, was conserved across multiple lineages, leading to high-level resistance and preceding the appearance of drug target mutations. Interestingly, in populations evolved from parental strains lacking the lfrA efflux pump, the primary target of the lfrR regulator, no lfrR gene mutations are selected. Furthermore, evolutional trajectories originating from the ΔlfrA strain displayed early arrest in some lineages and the absence of target gene mutations in those that evolved, albeit delayed. Thus, blocking or inhibiting the expression of efflux pumps can arrest or delay the fixation of drug target mutations, potentially limiting the maximum attainable resistance levels.

Prolonged vs intermittent intravenous infusion of β-lactam antibiotics for patients with sepsis: a systematic review of randomized clinical trials with meta-analysis and trial sequential analysis

BackgroundThe prolonged β-lactam antibiotics infusion has been an attractive strategy in severe infections, because it provides a more stable free drug concentration and a longer duration of free drug concentration above the minimum inhibitory concentration (MIC). We conducted this systematic review of randomized clinical trials (RCTs) with meta-analysis and trial sequential analysis (TSA) to compare the effects of prolonged vs intermittent intravenous infusion of β-lactam antibiotics for patients with sepsis.MethodsThis study was prospectively registered on PROSPERO database (CRD42023447692). We searched EMBASE, PubMed, and Cochrane Library to identify eligible studies (up to July 6, 2023). Any study meeting the inclusion and exclusion criteria would be included. The primary outcome was all-cause mortality within 30 days. Two authors independently screened studies and extracted data. When the I2 values < 50%, we used fixed-effect mode. Otherwise, the random effects model was used. TSA was also performed to search for the possibility of false-positive (type I error) or false-negative (type II error) results.ResultsA total of 4355 studies were identified in our search, and nine studies with 1762 patients were finally included. The pooled results showed that, compared with intermittent intravenous infusion, prolonged intravenous infusion of beta-lactam antibiotics resulted in a significant reduction in all-cause mortality within 30 days in patients with sepsis (RR 0.82; 95%CI 0.70–0.96; P = 0.01; TSA-adjusted CI 0.62–1.07). However, the certainty of the evidence was rated as low, and the TSA results suggested that more studies were needed to further confirm our conclusion. In addition, it is associated with lower hospital mortality, ICU mortality, and higher clinical cure. No significant reduction in 90-day mortality or the emergence of resistance bacteria was detected between the two groups.ConclusionsProlonged intravenous infusion of beta-lactam antibiotics in patients with sepsis was associated with short-term survival benefits and higher clinical cure. However, the TSA results suggested that more studies are needed to reach a definitive conclusion. In terms of long-term survival benefits, we could not show an improvement.

Antimicrobial Resistance in Bacteria from Meat and Meat Products: A One Health Perspective.

According to the 2030 Agenda of the United Nations, one of the sustainable development goals is to ensure sustainable consumption and production patterns. The need to ensure food safety includes, other than microbiological hazards, concerns with antimicrobial-resistant (AMR) bacteria. The emergence of resistant bacteria in the food industry is essentially due to the abusive, and sometimes incorrect, administration of antimicrobials. Although not allowed in Europe, antimicrobials are often administered to promote animal growth. Each time antimicrobials are used, a selective pressure is applied to AMR bacteria. Moreover, AMR genes can be transmitted to humans through the consumption of meat-harbouring-resistant bacteria, which highlights the One Health dimension of antimicrobial resistance. Furthermore, the appropriate use of antimicrobials to ensure efficacy and the best possible outcome for the treatment of infections is regulated through the recommendations of antimicrobial stewardship. The present manuscript aims to give the current state of the art about the transmission of AMR bacteria, particularly methicillin-resistant S. aureus, ESBL-producing Enterobacteriaceae, and vancomycin-resistant Enterococcus spp., along with other ESKAPE bacteria, from animals to humans through the consumption of meat and meat products, with emphasis on pork meat and pork meat products, which are considered the most consumed worldwide.

Immobilization of purified enzyme EreB in metalorganic framework (MOF) mesopores for erythromycin degradation

Erythromycin, a commonly used macrolide antibiotic, plays a crucial role in both human medicine and animal husbandry. However, its abuse has led to residual presence in the environment, with problems such as the emergence of resistant bacteria and enrichment of resistance genes. These issues pose significant risks to human health. Thus far, there are no effective, environmentally friendly methods to manage this problem. Enzymes can specifically degrade erythromycin without causing other problems, but their unrecyclability and environmental vulnerability hinder large-scale application. Enzyme immobilization may help to solve these problems. This study used Cu-BTC, a synthetic metal-organic framework, to immobilize the erythromycin-degrading enzyme EreB. The loading temperature and enzyme quantity were optimized. The Cu-BTC and EreB@Cu-BTC were characterized by various methods to confirm the preparation of Cu-BTC and immobilization of EreB. The maximum enzyme loading capacity was 66.5 mg g−1. In terms of enzymatic properties, immobilized EreB had improved heat (25–45 °C) and alkaline (6.5–10) tolerance, along with greater affinity between the enzyme and its substrate; Km decreased from 438.49 to 372.30 mM. Recycling was also achieved; after 10 cycles, 57.12% of the enzyme activity was maintained. After composite degradation, the antibacterial activity of erythromycin-containing wastewater was examined; the results showed that the novel composite could completely inactivate erythromycin. In summary, Cu-BTC was an ideal carrier for immobilization of the enzyme EreB, and the EreB@Cu-BTC composite has good prospects for the treatment of erythromycin-containing wastewater.

Integrating molecular docking and molecular dynamics simulation studies on the affinity and interactions of piperine with β-lactamase class A enzymes

ContextOne of the major problems facing health systems is the emergence of resistant bacteria. Emerge of extended spectrum of bacterial generated β-lactamases, due to genetic variation, has reduced the effectiveness of β-lactam antibiotics. Hydrolysis of the rings in the structure of β-lactam antibiotics that performed by β-lactamases lead to Bacterial resistance. It is necessary to discover compounds with beta-lactamase inhibitory properties. This work proposes piperine which is the main components of the black pepper and has several medicinal activities can be used as inhibitor of β-lactamase. Molecular docking results show that piperine bounded to all three β-lactamase class A enzymes and has suitable binding energies ranging from −6.43 to −6.66 kcal/mol. Analysis of the MD simulation trajectories predicted the formation of stable hydrogen bonds between piperine and all three β-lactamase class A enzymes during the whole simulation time which confirmed the molecular docking results. MethodsMolecular docking were performed to determine the binding pose and binding energy of class A beta lactamase with piperine using Autodock 4.2.2 software. Then the lowest conformation in the high populated cluster chosen for further analysis. Finally molecular dynamic simulation was carried out for three enzymes utilizing GROMACS 2019.6 program applying AMBER99SB force field.

Antibacterial activity and GC-MS profile of secondary metabolites of Bacillus subtilis subsp. subtilis HSFI-9 associated with Holothuria scabra

Abstract. Rakhmawatie MD, Marfu’ati N, Barsaliputri B, Fikriyah AZ, Ethica SN. 2023. Antibacterial activity and GC-MS profile of secondary metabolites of Bacillus subtilis subsp. subtilis HSFI-9 associated with Holothuria scabra. Biodiversitas 24: 2843-2849. The emergence of resistant bacteria has led to the importance of new antibacterial discovery. Before this research, the marine biota Holothuria scabra found in the Kodek gulf area, West Nusa Tenggara, Indonesia, was explored to isolate Bacillus sp. The present research was conducted to explore Bacillus sp. to produce secondary antibacterial metabolites, by culturing isolate using media containing starch, yeast, and peptone. Ethyl acetate was used for secondary metabolite extraction. Antibacterial activity screening was carried out by two-fold microdilution test to obtain Minimum Inhibitory Concentration (MIC) value. In this study, it was found that the ethyl acetate extract of the strain HSFI-9 can inhibit the growth of Staphylococcus aureus, Extended Spectrum ?-Lactamase (ES?L)-Escherichia coli, and Mycobacterium smegmatis with sequential minimum inhibitory concentrations (MIC) values ??of 3.125; 25; and 50 µg/mL. Based on phylogenetic tree analysis, the strain HSFI-9 show 99.71 similarity with Bacillus subtilis subsp. subtilis. The ethyl acetate extract of Bacillus subtilis subsp. subtilis HSFI-9 metabolomics profile was analyzed using Gas Chromatography-Mass Spectroscopy (GC-MS). It showed five volatile secondary metabolites, with the first dominant compound being (2S, 3S)-(-)-3-propyloxiranemethanol (MW 116, C6H12O2) with an area of ??34.78% (database similarity index of 73.3%). This study concluded that B. subtilis subsp. subtilis HSFI-9 could be further developed as an antibacterial producer.

The use of aminopenicillins in animals within the EU, emergence of resistance in bacteria of animal and human origin and its possible impact on animal and human health.

Aminopenicillins have been widely used for decades for the treatment of various infections in animals and humans in European countries. Following this extensive use, acquired resistance has emerged among human and animal pathogens and commensal bacteria. Aminopenicillins are important first-line treatment options in both humans and animals, but are also among limited therapies for infections with enterococci and Listeria spp. in humans in some settings. Therefore, there is a need to assess the impact of the use of these antimicrobials in animals on public and animal health. The most important mechanisms of resistance to aminopenicillins are the β-lactamase enzymes. Similar resistance genes have been detected in bacteria of human and animal origin, and molecular studies suggest that transmission of resistant bacteria or resistance genes occurs between animals and humans. Due to the complexity of epidemiology and the near ubiquity of many aminopenicillin resistance determinants, the direction of transfer is difficult to ascertain, except for major zoonotic pathogens. It is therefore challenging to estimate to what extent the use of aminopenicillins in animals could create negative health consequences to humans at the population level. Based on the extent of use of aminopenicillins in humans, it seems probable that the major resistance selection pressure in human pathogens in European countries is due to human consumption. It is evident that veterinary use of these antimicrobials increases the selection pressure towards resistance in animals and loss of efficacy will at minimum jeopardize animal health and welfare.

Abstract 3456: Synergistic drug combinations promote the development of resistance in acute myeloid leukemia

Abstract Background: Combination therapies are frequently employed as part of cancer treatment, often with the goal of preventing or slowing the development of drug resistance. Empirically developed combination therapies have had remarkable impact on cancer survival, yet the task of using preclinical data to predict combinations that will yield clinical benefits remains a challenge. Current combination strategies often prioritize drug synergy, where short-term effect of a drug combination is more than additive. However, prior studies of antibiotic resistance have shown that synergistic combinations can accelerate the emergence of resistance in bacteria. This occurs because synergistic drugs rely on one another for activity, resistance to one drug in the combination thereby depletes the efficacy of both. Consistent with experimental data on antibiotics, computational models of tumor evolution have predicted that when comparing equally active synergistic and non-synergistic combinations, synergy will accelerate the development of resistance in cancer cells. Methods: In this study we aim to experimentally determine if synergistic drug combinations promote the development of resistance in acute myeloid leukemia cell lines, MOLM-13 and OCI-AML2. Using live-cell imaging we measured changes in growth rate over 21 days to observe the development of resistance to combination therapies ranging from additive to synergistic (Bliss score range - 1.6 to 19). We tested combinations of Venetoclax, Cytarabine, AZD5991, and AZD1775. We also measured the fitness benefit conferred from acquired resistance by comparing the difference between cellular growth rate during the first 72 hours of treatment and the maximum growth rate achieved by emerging resistant populations over the 21 day treatment. Results: When controlling for both activity and drug synergy using logistic regression, increased drug synergy is consistently predictive of increased likelihood of resistance development within 21 days (MOLM-13 p=0.001, OCI-AML2 p=0.007, n=150 per cell line). As previously predicted, there is also significant correlation between drug synergy and the fitness benefit of resistance (MOLM-13 R=0.71, p=1.6e-6). Furthermore, using a model of competing drug-sensitive and resistant subpopulations treated with combination therapy, we demonstrate that these observations are a mechanistic consequence of synergistic combination, whereby the fitness benefit acquired by gaining resistance to either drug in a synergistic combination is greater than the fitness benefit in a non-synergistic combination. Conclusion: Together these data have important implications for preclinical prioritization of combination therapies, and demonstrate that both short-term and long-term measures of drug efficacy can inform preclinical strategies aiming to develop novel combinations of cancer therapies with robust and durable efficacy. Citation Format: Emily Mason-Osann, Amy E. Pomeroy, Adam C. Palmer, Jerome T. Mettetal. Synergistic drug combinations promote the development of resistance in acute myeloid leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3456.

Antibiotic Susceptibility Pattern of Staphylococcus Aureus and Escherichia Coli Isolated from Urinary Tract Infection (UTI) Patients Attending Murtala Muhammad Specialist Hospital, Kano, Kano State, Nigeria

The widespread use of antibiotics both inside and outside of medicine is playing a significant role in the emergence of resistant bacteria. The study was aimed to determine the antibiotic sensitivity patterns of Staphylococcus aureus and Escherichia coli isolated from Urinary Tract Infected (UTI) patients. Antibiotic susceptibility patterns of the bacterial isolates were determined using modified Kirby Bauer method. The susceptibility of antibiotic against S. aureus showed that most of the isolates were resistant to more than 3 antibiotics. Most of the isolates were sensitive to gentamicin, ofloxacin, Septrin and Augmentin. However, the isolates were more resistant to streptomycin, Nalidixic acid and levofloxacin. The susceptibility pattern of S. aureus against the antibiotics showed that 14 out of the 20 isolates were multi drug resistant. For E. coli, result showed that most of the isolates were resistant to more than 3 antibiotics. Most of the isolates were sensitive to Levofloxacin, ofloxacin, Streptomycin and gentamicin. However, the isolates were more resistant to Ceporex, Augmentin and ampicillin and 14 out of the 20 isolates were multi drug resistant. It is concluded that the bacteria isolated from UTI patients are mostly resistance to some classes of antibiotics. Keywords: Urinary Tract Infection (UTI) and antibiotics

Resistance-resistant antibacterial treatment strategies.

Antibiotic resistance is a major danger to public health that threatens to claim the lives of millions of people per year within the next few decades. Years of necessary administration and excessive application of antibiotics have selected for strains that are resistant to many of our currently available treatments. Due to the high costs and difficulty of developing new antibiotics, the emergence of resistant bacteria is outpacing the introduction of new drugs to fight them. To overcome this problem, many researchers are focusing on developing antibacterial therapeutic strategies that are "resistance-resistant"-regimens that slow or stall resistance development in the targeted pathogens. In this mini review, we outline major examples of novel resistance-resistant therapeutic strategies. We discuss the use of compounds that reduce mutagenesis and thereby decrease the likelihood of resistance emergence. Then, we examine the effectiveness of antibiotic cycling and evolutionary steering, in which a bacterial population is forced by one antibiotic toward susceptibility to another antibiotic. We also consider combination therapies that aim to sabotage defensive mechanisms and eliminate potentially resistant pathogens by combining two antibiotics or combining an antibiotic with other therapeutics, such as antibodies or phages. Finally, we highlight promising future directions in this field, including the potential of applying machine learning and personalized medicine to fight antibiotic resistance emergence and out-maneuver adaptive pathogens.

Effect of Antibiotic Exposure on Staphylococcus epidermidis Responsible for Catheter-Related Bacteremia.

Coagulase-negative staphylococci (CoNS) and especially Staphylococcus epidermidis are responsible for health care infections, notably in the presence of foreign material (e.g., venous or central-line catheters). Catheter-related bacteremia (CRB) increases health care costs and mortality. The aim of our study was to evaluate the impact of 15 days of antibiotic exposure (ceftobiprole, daptomycin, linezolid and vancomycin) at sub-inhibitory concentration on the resistance, fitness and genome evolution of 36 clinical strains of S. epidermidis responsible for CRB. Resistance was evaluated by antibiogram, the ability to adapt metabolism by the Biofilm Ring test® and the in vivo nematode virulence model. The impact of antibiotic exposure was determined by whole-genome sequencing (WGS) and biofilm formation experiments. We observed that S. epidermidis strains presented a wide variety of virulence potential and biofilm formation. After antibiotic exposure, S. epidermidis strains adapted their fitness with an increase in biofilm formation. Antibiotic exposure also affected genes involved in resistance and was responsible for cross-resistance between vancomycin, daptomycin and ceftobiprole. Our data confirmed that antibiotic exposure modified bacterial pathogenicity and the emergence of resistant bacteria.

GC-MS Analysis and Microbiological Evaluation of Caraway Essential Oil as a Virulence Attenuating Agent against Pseudomonas aeruginosa

The emergence of resistant microbes threatens public health on our planet, and the emergence of resistant bacteria against the most commonly used antibiotics necessitates urgent alternative therapeutic options. One way to fight resistant microbes is to design new antimicrobial agents, however, this approach takes decades of research. An alternative or parallel approach is to target the virulence of bacteria with natural or synthetic agents. Active constituents from medicinal plants represent a wide library to screen for natural anti-virulence agents. Caraway is used as a traditional spice and in some medicinal applications such as carminative, antispasmodic, appetizer, and expectorant. Caraway essential oil is rich in terpenes that were previously reported to have antimicrobial activities. In our study, we tested the caraway essential oil in sub-inhibitory concentration as a virulence agent against the Gram-negative bacteria Pseudomonas aeruginosa. Caraway essential oil in sub-inhibitory concentration dramatically blocked protease activity, pyocyanin production, biofilm formation, and quorum sensing activity of P. aeruginosa. The gas chromatography-mass spectroscopy (GC-MS) profile of caraway fruit oil identified 13 compounds representing 85.4% of the total oil components with carvone and sylvestrene as the main constituents. In conclusion, caraway essential oil is a promising virulence-attenuating agent that can be used against topical infections caused by P. aeruginosa.

Molecular Evaluation of the Impact of Nd:YAG Laser and Static Magnetic Field on Genomic DNA of Some Bacterial Isolates using RAPD-PCR

Antimicrobial therapy is frequently associated with the emergence of resistant bacteria with a high rate of morbidity and mortality worldwide. The present study was aimed at investigating the impact of a neodymium-doped yttrium aluminum (Nd:YAG) laser, and a static magnetic field (SMF) on cellular growth and DNA alteration in some clinical bacterial isolates. Samples from cutaneous wounds were collected by sterile cotton swabs from three elderly women admitted to Tikrit Teaching Hospital, Tikrit City, Iraq. Isolation and identification of Streptococcus agalactiae, Staphylococcus aureus, and Pseudomonas aeruginosa were carried out using cultural characteristics, microscopy, and biochemical tests. Three broth cultures were prepared for each of the test isolates. The first broth culture served as untreated control, the second was exposed to an Nd:YAG laser and the third was exposed to SMF. Colony counting was done on all the samples. DNA was extracted from the test bacteria and used to perform the RAPD-PCR assay. In contrast to the untreated control, the results showed that Nd:YAG laser radiation was more effective than SMF at inhibiting the cellular growth of the test isolates. Also, the radiation caused DNA alteration, which was established by decreased microbial growth, as well as the development of new bands and the loss of original bands. According to the findings of this study, the Nd:YAG laser is a promising technique for influencing the healing of infected cutaneous wounds. RAPD-PCR is also a useful biomarker assay for assessing the biological impact of laser radiation and SMF on bacteria.

Development of Hydroxamic Acid Compounds for Inhibition of Metallo-β-Lactamase from Bacillus anthracis.

The emergence of resistant bacteria takes place, endangering the effectiveness of antibiotics. A reason for antibiotic resistance is the presence of lactamases that catalyze the hydrolysis of β-lactam antibiotics. An inhibitor of serine-β-lactamases such as clavulanic acid binds to the active site of the enzymes, thus solving the resistance problem. A pressing issue, however, is that the reaction mechanism of metallo-β-lactamases (MBLs) hydrolyzing β-lactam antibiotics differs from that of serine-β-lactamases due to the existence of zinc ions in the active site of MBLs. Thus, the development of potential inhibitors for MBLs remains urgent. Here, the ability to inhibit MBL from Bacillus anthracis (Bla2) was investigated in silico and in vitro using compounds possessing two hydroxamate functional groups such as 3-chloro-N-hydroxy-4-(7-(hydroxyamino)-7-oxoheptyl)benzamide (Compound 4) and N-hydroxy-4-(7-(hydroxyamino)-7-oxoheptyl)-3-methoxybenzamide (Compound 6). In silico docking and molecular dynamics simulations revealed that both Compounds 4 and 6 were coordinated with zinc ions in the active site, suggesting that the hydroxamate group attached to the aromatic ring of the compound plays a crucial role in the coordination to the zinc ions. In vitro kinetic analysis demonstrated that the mode of inhibitions for Compounds 4 and 6 were a competitive inhibition with Ki values of 6.4 ± 1.7 and 4.7 ± 1.4 kcal/mol, respectively. The agreement between in silico and in vitro investigations indicates that compounds containing dihyroxamate moieties may offer a new avenue to overcome antibiotic resistance to bacteria.

Synergistic Effect of Quercetin on Antibacterial Activity of Florfenicol Against Aeromonas hydrophila In Vitro and In Vivo.

The overuse or abuse of antimicrobial drugs in aquaculture, aggravates the generation of drug-resistant bacteria, which has caused potential risks to human health and the aquaculture industry. Flavonoid–antibiotic combinations have been shown to suppress the emergence of resistance in bacteria, and sometimes even reverse it. Here, the antibacterial activity of florfenicol in combination with quercetin, a potential drug to reverse multidrug resistance, was tested against Aeromonas hydrophila (A. hydrophila). Of eleven selected antimicrobial agents, quercetin and florfenicol showed the strongest bactericidal effect, and fractional inhibitory concentration (FIC) indices were 0.28, showing a highly synergistic effect. Then, the antibacterial activities of quercetin and florfenicol against A. hydrophila were further tested in vitro and in vivo. Bacterial viability of A. hydrophila decreased in a florfenicol dose-dependent manner, about 16.3–191.4-fold lower in the presence of 15 μg/mL quercetin and 0.156 to 1.25 μg/mL florfenicol than in the absence of quercetin, respectively. The cell killing was maximum at 45 μg/mL quercetin in the dose range tested plus 0.156 μg/mL florfenicol. The viability decreased over time during the combined treatment with quercetin and florfenicol by 60.5- and 115-fold in 0.156 μg/mL florfenicol and 0.625 μg/mL florfenicol, respectively. Additionally, the synergistic effect was confirmed by the bacterial growth curve. Furthermore, quercetin and florfenicol had an obvious synergistic activity in vivo, reducing the bacterial load in the liver, spleen and kidney tissues of Cyprinus carpio up to 610.6-fold compared with the florfenicol group, and improving the survival rate of infected fish from 10% in the control group to 90% in drug combinations group. These findings indicated that quercetin could potentiate the antibacterial activity of florfenicol against A. hydrophila infection and may reduce the use of antimicrobial drugs and improve the prevention and control capability of bacterial resistance.

Knowledge, Attitudes, and Risk Perception of Broiler Grow-Out Farmers on Antimicrobial Use and Resistance in Oyo State, Nigeria.

Assessing knowledge, attitudes, and risk perception of Nigerian broiler grow-out farmers (n = 152) to antimicrobial resistance (AMR) with a five sectional purposive-structured-questionnaire: demographics; knowledge; attitudes; risk-perception; and response to regulation of antimicrobial practices. Data were analyzed using descriptive statistics, chi-square test, and binary logistic regression. Respondents’ knowledge score, in total, was lower than average, with all (100%) respondents having the understanding that antibiotics kill/reduce bacteria, most participants (>73%) believing that feeding antibiotics to broiler chickens is a necessity for weight gain, and many (>69%) thinking that no negative side-effects exist with the use of antibiotics. Poor attitude towards antimicrobial usage was prevalent (>63%) with unsatisfactory performance in most instruments: >60% of farmers reported using antimicrobials every week and still use antimicrobials when birds appear sick, and most (>84%) arbitrarily increase the drug dosages when used. However, a satisfactory performance score was reported (68%) in risk perception of AMR with >63% perceiving that inappropriate use of antibiotics is the main factor causing the emergence of resistant bacteria; >65.8% expressed that AMR in broiler chickens is not essential for public health, that AMR cannot develop from broiler bacteria diseases, that increasing the frequency of antimicrobial use cannot increase AMR in future, and that usage cannot lead to antibiotic residue in broiler-meat products leading to AMR development in human. None of the respondents were aware of any regulation for monitoring antimicrobial use. Significant factors associated with knowledge, attitudes, and risk perception of antimicrobial use and resistance among broiler grow-out farmers include marital status, farm category, education, educational specialization, sales target, growth duration/cycle, broiler stocking batch, and feed source. Identified gaps exist in AMR awareness among Nigerian broiler farmers and should be targeted through stakeholders’ participation in combatting AMR threats.