Use Of Antibiotics Worldwide Research Articles

Recent developments in antibiotic contamination of animal products, soil, and water worldwide

Abstract Antimicrobial resistance (AMR), facilitated by antibiotic consumption, remains one of the biggest threats to global health and food security. The burgeoning AMR has an estimated forecast of 10 million deaths and 100 trillion USD economic losses annually worldwide by 2050 if no urgent actions are taken. The indiscriminate use of antibiotics in food animal production plays an expressive role in the AMR crisis. This paper compiles information regarding antibiotics and AMR in animals, animal-derived products, and agriculture-impacted environment. A holistic approach is needed to mitigate the burden of AMR within the context of human-animal-environment. Currently there are few approaches to this problem such as nanotechnology, anaerobic digestion, biochar composting, and alternatives to antibiotic treatments (like herbal plant extracts, probiotics, vaccines, enzymes, and antimicrobial peptides) have been developed. However, there are gaps in knowledge about AMR and areas for improvement are obvious. There is no a clear path to put an end to the persistent trends of AMR. Despite the trends for stricter regulation on the use of antibiotics worldwide, they find their way into food animal production, water, and soil as a result of misuses in many countries. We need to acknowledge the antibiotic contamination and/or AMR as a silent pandemic, and we are challenged to adopt a global approach to reducing and improving their use.

Adsorption of antibiotics by bentonite-chitosan composite: Phenomenological modeling and physical investigation of the adsorption process

The increased use of antibiotics worldwide turned into a serious preoccupation due to their environmental and health impacts. Since the majority of antibiotic residuals are hardly eliminated from wastewater, based on usual methods, other treatments receive considerable attention. Adsorption is known as the most effective method of the treatment of antibiotics. In this paper, the adsorption isotherms of doripenem, ampicillin, and amoxicillin on bentonite-chitosan composite are determined at three temperatures, T = 303.15, 313.15 and 323.15 K, which are used to achieve a theoretical investigation of the removal phenomenon, based on a statistical physics theory. Three analytical models are utilized to describe the AMO, AMP, and DOR adsorption phenomena at the molecular level. From the fitting results, all antibiotic adsorption on a BC adsorbent is associated with the monolayer formation with one type of site. Concerning the number of adsorbed molecules per site (n), it is concluded that multi-docking (n < 1) and multi-molecular (n > 1) phenomena are feasible for AMO, AMP, and DOR adsorption on BC. The adsorption amounts at saturation of the BC adsorbent, deduced by the monolayer model, are found to be 70.4–88.0 mg/g for doripenem, 57.8–79.2 mg/g for ampicillin and 38.6–67.5 mg/g for amoxicillin indicating that the antibiotics adsorption performance of BC was greatly depended on temperature where the adsorption capacities increased with the increment of this operating variable. All adsorption systems are demonstrated by a calculation of the energy of adsorption, considering that the extrication of these pollutants implies physical interactions. The thermodynamic interpretation confirms the spontaneous and feasible nature of the adsorption of the three antibiotics on BC adsorbent. In brief, BC sample is regarded as a promising adsorbent to extract antibiotics from water and presents important potentials to be effected in wastewater handling at industrial level.

Occurrence of Nine Antibiotics in Different Kinds of Sewage Sludge, Soils, Corn and Grapes After Sludge Spreading

The huge worldwide use of antibiotics triggers the accumulation of these substances in sludge from wastewater treatment plants (WWTP) and the possible contamination of soils amended with it, as well as of crops growing in these soils. In this work we analyzed the presence of the antibiotics amoxicillin (AMO), cefuroxime (CEF), ciprofloxacin (CIP), clarithromycin (CLA), levofloxacin (LEV), lincomycin (LIN), norfloxacin (NOR), sulfadiazine (SUL), and trimethoprim (TRI), in sludge from different WWTPs in Galicia (NW Spain), as well as in sludge technically treated by waste-managers, in soils where treated sludge was applied, and in crops (corn and vineyard) growing in the amended areas. The antibiotics were quantified by means of high resolution HPLC-mass-chromatography. The results indicate that almost all the sludge samples contained antibiotics, being ciprofloxacin and levofloxacin the most abundant reaching maximum values of 623 and 893 ng/g, respectively. The sludge treatment significantly reduced the number and the concentrations of antibiotics. In 12% of the soil samples where sludge was applied, some antibiotics were detected, but always in small concentrations. Regarding the crops, no antibiotic was detected in the roots, stalk, leaves and grain of corn, neither in grapes sampled in vineyards. It can be concluded that the treatments currently applied in the WWTPs under study are not totally effective in removing antibiotics from the sludge, although the findings of this research suggest that the additional specific treatment of the sludge derived from these WWTPs is effective in reducing the risk of environmental pollution due to a variety of antibiotics, and specifically in the case of soils amended with these organic materials and crops growing on it.

Antimicrobial mechanisms of traditional Chinese medicine and reversal of drug resistance: a narrative review.

In recent years, the extensive use of antibiotics worldwide has led to an increase in the number of drug-resistant bacterial strains, thus resulting in an increasingly severe degree of bacterial resistance. For thousands of years, traditional Chinese medicine (TCM) has provided natural and unique advantages in the treatment of infectious diseases. Therefore, it is important to develop further and use TCM to treat clinical infections caused by drug-resistant bacteria. A literature search was performed using PubMed, Web of Science, Google Scholar, and the China National Knowledge Infrastructure databases. The articles were analyzed to extract information on the antimicrobial effects of Chinese herbal medicines, compounded Chinese medicines, monomeric compounds of herbal origin, and the combined use of Chinese medicine and antimicrobial drugs and to determine the synergistic effect of the combination of Chinese medicine and antibiotics, as well as investigate the possibility of restoring the antibiotic sensitivity of drug-resistant strains. The mechanisms underlying the antibacterial properties of TCM involve altering membrane permeability, inhibiting protein and nucleic acid synthesis, inhibiting enzyme activity in vivo, and controlling the ability of pathogenic bacteria. In addition, the mechanism underlying TCM-induced reversal of bacterial drug resistance is discussed, particularly in terms of the elimination of resistant (R) plasmids and the inhibition of extended-spectrum β-lactamases, bacterial biofilm formation, and bacterial efflux pump activity. This paper reviewed the recent relevant literature on antimicrobial action and its mechanisms, as well as the mechanisms of drug resistance reversal by TCM to provide a reference for clinical drug use, prevention and control of bacterial infection, and research and development of new drugs.

Antibiotic pollution in lakes in China: Emission estimation and fate modeling using a temperature-dependent multimedia model

The high use of antibiotics worldwide has poses a serious threat to both human and environmental health. Lakes are served as reservoirs for antibiotics, however, there is a lack of information available on antibiotics emissions and the subsequent pollution. Here, the emission and fate of 34 frequently detected antibiotics were studied in 226 Chinese lakes, via the built emission estimation method and a temperature-dependent multimedia lake model. It has been estimated that totally 5711 tons antibiotic were discharged into the lakes of China in 2019. Antibiotics emissions are due to human activities, with 3800-fold higher emissions in the Eastern China than that in Western China. The antibiotic fate in lakes has been successfully modelled by simulating the lake stratification, freeze-melt cycles and the stable condition throughout the year. Both stratification and freeze-melt cycles can lead to increased antibiotic concentrations in lake water. Deep-water lakes were shown to serve as a highly effective natural storage medium for antibiotics. The reliability of the model was confirmed by published measured concentrations and Monte Carlo method. This is the first study to comprehensively investigate the antibiotic fate in lakes of China, providing valuable guidance for the remediation of contaminated lakes.

Pretreatment Methods for the Determination of Antibiotics Residues in Food Samples and Detected by Liquid Chromatography Coupled with Mass Spectrometry Detectors: A Review.

With the increasing use of antibiotics worldwide, antibiotic monitoring has become a topic of concern. After metabolizing of antibiotics in animals, the metabolites enter the environment through excreta or ingested by the human body via food chain that may exacerbate the emergence of antibiotic resistance and then threaten human's life. This article summarized several analytical methods used for the determination of antibiotics in recent 10years. Due to the complex matrices and low concentration level of antibiotics in the food samples, a reliable analysis method is required to maximize the recovery rate. Several techniques like solid phase extraction (SPE), dispersive liquid-liquid microextraction (DLLME) and QuEChERS have been frequently used in the pretreatment process for analytes extraction and concentration. After the pretreatment, ultra-high performance liquid chromatography combined with mass spectrometry has been a reliable method for quantitative analysis and is able to determine multiple antibiotics simultaneously. This review also gives an overview about analytical conditions for antibiotics residues in different food samples and their method validation parameters.

Disruption of the Cytoplasmic Membrane Structure and Barrier Function Underlies the Potent Antiseptic Activity of Octenidine in Gram-Positive Bacteria.

ABSTRACTThe antimicrobial killing mechanism of octenidine (OCT), a well-known antiseptic is poorly understood. We recently reported its interaction with Gram-negative bacteria by insertion of OCT into the outer and cytoplasmic membrane of Escherichia coli, resulting in a chaotic lipid rearrangement and rapid disruption of the cell envelope. Its action primarily disturbs the packing order of the hydrophobic moiety of a lipid, which consequently might result in a cascade of multiple effects at a cellular level. Here, we investigated OCT’s impact on two different Gram-positive bacteria, Enterococcus hirae and Bacillus subtilis, and their respective model membranes. In accordance with our previous results, OCT induced membrane disorder in all investigated model systems. Electron and fluorescence microscopy clearly demonstrated changes in cellular structure and membrane integrity. These changes were accompanied by neutralization of the surface charge in both E. hirae and B. subtilis and membrane disturbances associated with permeabilization. Similar permeabilization and disordering of the lipid bilayer was also observed in model membranes. Furthermore, experiments performed on strongly versus partly anionic membranes showed that the lipid disordering effect induced by OCT is a result of maximized hydrophobic over electrostatic forces without distinct neutralization of the surface charge or discrimination between the lipid head groups. Indeed, mutants lacking specific lipid head groups were also susceptible to OCT to a similar extent as the wild type. The observed unspecific mode of action of OCT underlines its broad antimicrobial profile and renders the development of bacterial resistance to this molecule less likely.IMPORTANCE OCT is a well-established antiseptic molecule routinely used in a large field of clinical applications. Since the spread of antimicrobial resistance has restricted the use of antibiotics worldwide, topically applied antiseptics like OCT, with a broad spectrum of antimicrobial activity and high safety profile, gain increasing importance for effective infection prevention and therapy. To eliminate a wide spectrum of disease-causing microorganisms, a compound’s antiseptic activity should be unspecific or multitarget. Our results demonstrate an unspecific mechanism of action for OCT, which remained largely unknown for years. OCT disturbs the barrier function of a bacterial cell, a function that is absolutely fundamental for survival. Because OCT does not distinguish between lipids, the building blocks of bacterial membranes, its mode of action might be attributed to all bacteria, including (multi)drug-resistant isolates. Our results underpin OCT’s potent antiseptic activity for successful patient outcome.

Solar Light-Assisted Oxidative Degradation of Ciprofloxacin in Aqueous Solution by Iron(III) Chelated Cross-Linked Chitosan Immobilized on a Glass Plate

The massive worldwide use of antibiotics leads to water pollution and increasing microbial resistance. Hence, the removal of antibiotic residues is a key issue in water remediation. Here, we report the solar light-assisted oxidative degradation of ciprofloxacin (CPF), using H2O2 in aqueous solution, catalyzed by iron(III) chelated cross-linked chitosan (FeIII-CS-GLA) immobilized on a glass plate. The FeIII-CS-GLA catalyst was characterized by FTIR and 57Fe-Mössbauer spectroscopies as well as X-ray diffraction, revealing key structural motifs and a high-spin ferric character of the metal. Catalytic degradation of CPF was investigated as a function of solar light irradiation time, solution pH, concentration of H2O2 and CPF, as well as cross-linker dosage and iron(III) content in FeIII-CS-GLA. The system was found to serve as an efficient catalyst with maximum CPF degradation at pH 3. The specific ·OH scavenger mannitol significantly reduces the degradation rate, indicating that hydroxyl radicals play a key role. The mechanism of catalytic CPF degradation was evaluated in terms of pseudo-first-order and Langmuir-Hinshelwood kinetic models; adsorption of CPF onto the FeIII-CS-GLA surface was evidenced by field emission scanning electron microscopy coupled with energy dispersive X-ray spectroscopy. FeIII-CS-GLA can be reused multiple times with only minor loss of catalytic efficiency. Antimicrobial activity tests performed against both Gram-negative (Escherichia coli DH5α, Salmonella typhi AF4500) and Gram-positive bacteria (Bacillus subtilis RBW) before and after treatment confirmed complete degradation of CPF. These results establish the immobilized FeIII-CS-GLA as a rugged catalyst system for efficient photo-Fenton type degradation of antibiotics in aqueous solutions.

Worldwide Traceability of Antibiotic Residues from Livestock in Wastewater and Soil: A Systematic Review.

Simple SummaryThis work focuses on reviewing research works on antibiotic residues, evaluating antibiotics used in livestock production and their excretion in animal products and in environmental matrices such as water and soil worldwide, according to each of the variables used such as antibiotic family, name, concentration (% and mg/kg or ppm), country, and continent where the residue was found. The main antibiotics used worldwide and in animal production are sulfonamides, tetracyclines, quinolones, penicillin, and cephalosporins.The use of antibiotics in animal production are widely used for disease treatment, health protection, and as growth promoters. Common antibiotics used in veterinary medicine are excreted and eliminated through the sewage system, contaminating water and soil with negative effects on agricultural activities. This systematic review focuses on the trend of research works on antibiotic residues, evaluating antibiotics used in livestock production and their excretion in animal products and in environmental matrices such as water and soil. Our database was composed of 165 articles, reporting the concentration of antibiotic residues found in the environment, livestock (cow, sheep, pig, horse, chicken, rabbit, goat), aquatic and terrestrial animal tissues, animal products (milk and eggs), wastewater, and soil. The documents were obtained from Asia, Africa, North America, South America, Europe, and Oceania. A descriptive analysis of antibiotic residues found worldwide was analyzed according to each of the variables used such as antibiotic family, name, concentration (% and mg/kg or ppm), and country and continent where the residue was found. The descriptive analysis was carried out using the “describe” function of psych package and pirate plots were drawn. According to our study, the main antibiotics used worldwide in animal production are sulfonamides, tetracyclines, quinolones, penicillin, and cephalosporins. At present, despite the trends of increased regulations on the use of antibiotics worldwide, antibiotics are still utilized in food animal production, and are present in water and soil, then, there is still the misuse of antibiotics in many countries. We need to become aware that antibiotic contamination is a global problem, and we are challenged to reduce and improve their use.

Enrofloxacin perturbs nitrogen transformation and assimilation in rice seedlings (Oryza sativa L.)

The extensive use of antibiotics worldwide has led to phytotoxicity and high risks to humans. Although research on the physiological toxicity of antibiotics is extensive, its influence on plant nitrogen uptake and assimilation remains unclear. The effect of enrofloxacin on nitrogen transformation and assimilation in rice (Oryza sativa L.) seedlings was investigated in this study. Enrofloxacin had no significant effect on rice growth, nitrogen assimilation and metabolism at low concentration, while significant changes were observed in high concentration. The growth of rice seedlings was inhibited, nitrate uptake was enhanced and nitrogen content increased significantly in both shoots and roots in enrofloxacin (800 μg L−1) treatment. Furthermore, enrofloxacin promoted the activity of enzymes related to nitrogen assimilation, including nitrate reductase, nitrite reductase, glutamine synthetase, glutamate synthase, and glutamate dehydrogenase. High enzyme activity resulted in an increase in intermediate products and protein content, suggesting that rice seedlings may detoxify enrofloxacin stress through amino acid binding and nitro-oxidative stress might be one of the reasons of phenotype change. Gas chromatography-mass spectrometry results revealed that different types of metabolites in both shoots and roots increased with enrofloxacin stress. Specifically, glycine, serine, and threonine metabolism; aminoacyl-tRNA biosynthesis; alanine, aspartate, and glutamate metabolism; butanoate metabolism; glyoxylate and dicarboxylate metabolism in shoot; and tyrosine metabolism and citrate cycle in root were affected. Moreover, a significant correlation between nitrogen content, nitrogen assimilation enzyme activity, and metabolite content was observed. Collectively, these findings reveal the potential risks of using reclaimed wastewater irrigation and/or antibiotic-containing animal fertilizers on crops.

Antibiotics: Conventional Therapy and Natural Compounds with Antibacterial Activity-A Pharmaco-Toxicological Screening.

Antibiotics are considered as a cornerstone of modern medicine and their discovery offers the resolution to the infectious diseases problem. However, the excessive use of antibiotics worldwide has generated a critical public health issue and the bacterial resistance correlated with antibiotics inefficiency is still unsolved. Finding novel therapeutic approaches to overcome bacterial resistance is imperative, and natural compounds with antibacterial effects could be considered a promising option. The role played by antibiotics in tumorigenesis and their interrelation with the microbiota are still debatable and are far from being elucidated. Thus, the present manuscript offers a global perspective on antibiotics in terms of evolution from a historical perspective with an emphasis on the main classes of antibiotics and their adverse effects. It also highlights the connection between antibiotics and microbiota, focusing on the dual role played by antibiotics in tumorigenesis. In addition, using the natural compounds with antibacterial properties as potential alternatives for the classical antibiotic therapy is discussed.

Prevalence, Clinical Characteristics and Changes of Antibiotic Resistance in Children with Nontyphoidal Salmonella Infections from 2009-2018 in Chongqing, China.

PurposeNontyphoidal Salmonella (NTS) is a leading bacterial cause for acute gastroenteritis in children. With the increasing use of antibiotics worldwide, antibiotic resistance has become a global problem. However, data on NTS infections and changes in antibiotic resistance among children remain limited in China. We aimed to characterize the prevalence, clinical feature, serotype and the changes of antibiotic resistance of NTS in children in Chongqing.Methods501 hospitalized children with NTS infections (confirmed by positive NTS culture) in Children’s Hospital of Chongqing Medical University from January 2009 to December 2018 were included. The clinical data and drug sensitivity test results were retrospectively reviewed and analyzed. Antibiotic resistance in NTS infections was compared between 2009–2013 and 2014–2018.ResultsA total of 501 isolates were detected. Most NTS infections occurred in children under three years old, which mainly occurred between July and October. The numbers of patients with diarrhea, fever, and vomiting were 472 (94.2%), 422 (84.2%) and 146 (29.1%), respectively. Serogroup B (67.5%) was the predominant serogroup isolates. And Salmonella Typhimurium was the most common serotype (79.2%). The study compared the drug resistance of NTS from 2009 to 2013 with that from 2014 to 2018. We found the drug resistance rates of NTS to cefazolin, cefotaxime, ciprofloxacin, levofloxacin and imipenem showed an upward trend. The drug resistance rates of NTS to chloramphenicol, ampicillin, ceftriaxone, cefepime and compound sulfamethoxazole decreased slightly, but still showed high drug resistance rates. And drug resistance rates of NTS to piperacillin/tazobactam and ceftazidime decreased significantly in the last ten years. Multi-drug resistance (MDR) isolates, were detected among 69 cases (13.7%) of 501 children with NTS infections.ConclusionThe overall antibiotic resistance rates remained at a high level in Chongqing. Continuous surveillance of antibiotic resistance in NTS and control measures such as avoiding unnecessary antibiotic therapy in general NTS gastroenteritis are important. For severe or invasive infections caused by NTS infection in Southwest China, the use of ceftazidime is recommended until antibiotic sensitivity test results are available. And the choice of antibiotics should be based on the curative effect and the antibiotics sensitivity results.

Epidemiology of Community Origin Escherichia coli and Klebsiella pneumoniae Uropathogenic Strains Resistant to Antibiotics in Franceville, Gabon.

IntroductionUrinary tract infection is one of the major causes of consultation, microbiologic exploration, intensive use of antibiotics worldwide, and the second leading cause of clinical consultation in community practice. Many bacteria play a role in the urinary tract infections etiology, including Enterobacteriaceae such as Escherichia coli (E. coli) and Klebsiella spp.ObjectiveThe study’s main objective was to examine the epidemiology of E. coli and Klebsiella pneumoniae (K. pneumoniae) uropathogenic strains resistant to antibiotics in Franceville.MethodologyThe study was carried out between January 2018 and June 2019 in Franceville South-East Gabon. We examined a total of 1086 cytobacteriological urine samples. The identification of E. coli and K. pneumoniae strains was carried out using the Vitek-2 compact automated system and the antibiogram with the disk diffusion method according to the European Committee on Antimicrobial Susceptibility Testing recommendations.ResultsThe prevalence of urinary tract infections was 29.2% (317/1086), of which 25.1% and 4.1% were mono-infections and co-infections, respectively. The prevalence of UTIs with E. coli was 28.7% (91/317) with a predominance of isolation in women. K. pneumoniae was responsible for 16.2% (61/317) of UTIs. E. coli and K. pneumoniae Uropathogenic strains showed resistance to beta-lactams, quinolones and cotrimoxazole, whereas Nitrofurantoin, Amikacin, Imipenem and Ertapenem were the most active antibiotics against E. coli and K. pneumoniae uropathogenic strains.ConclusionThis study showed a high prevalence of urinary tract infections with a major implication of E.coli and K. pneumoniae strains. E. coli and K. pneumoniae presented high frequency of resistance to antibiotics, highlighting the need to adapt their use accordingly at the local level.

Adsorption and catalytic reduction of rifampicin in wastewaters using hybrid rGO@Fe/Pd nanoparticles

Ubiquitous use of antibiotics worldwide has resulted in their significant efflux into the environment impacting ecosystem health to such a degree that antibiotic removal has become a key environmental issue. Here one target antibiotic, rifampicin, was successfully removed from aqueous solution using a hybrid nanomaterial (rGO@Fe/Pd NP) having an adsorption capacity of 90.9 mg g−1. The factors influencing rifampicin removal by rGO@Fe/Pd NPs and each constituent component of the hybrid nanomaterial were also investigated. Adsorption and reduction kinetics indicated that rifampicin conformed to a pseudo-second-order model. While X-ray diffraction and Fourier transform infrared spectroscopy showed that rifampicin was adsorbed by rGO@Fe/Pd NPs, scanning electron microscopy and X-ray photoelectron spectroscopy showed that rifampicin was reduced by nano iron and during this process, nano palladium acted as a catalyst. Liquid chromatography-mass spectrometry, confirming that rifampicin was indeed catalytically degraded by rGO@Fe/Pd NPs, as evidenced by a decrease in ion mass ratio from 823.41 (M+1H) to 611.21 (M+1H) or 606.37 (M+1H). A mechanism for rifampicin degradation based on adsorption and catalytic reduction was proposed. In addition, the practical removal efficiency of rifampicin was successfully validated in aquaculture sewage water (71.9%) and for municipal sewage (58.1%). This article provides a strong scientific basis for the degradation mechanism of rifampicin by rGO@Fe/Pd NPs indicating that this hybrid material has great potential for practical applications.

Synergetic adsorption and Fenton-like oxidation for simultaneous removal of ofloxacin and enrofloxacin using green synthesized Fe NPs

Due to the widespread use of antibiotics worldwide in both medicine and agribusiness, many wastewaters often contain a range of different fluoroquinolone antibiotics such as ofloxacin (OFL) and enrofloxacin (ENR) in elevated concentrations. Simultaneous removal of such mixed antibiotics is a major challenge where the utility of using nanomaterials for such purposes is unknown. In this study, pre-adsorption followed by Fenton-like oxidation (sequential Fenton-like oxidation) was developed and shown to be useful for the simultaneous removal of OFL and ENR, with removal efficiencies of 91.8 and 90.7%, respectively. Changes in the surface of Fe NPs, before and after exposure to both FQs, were characterized by field emission scanning electron microscopy (FESEM), Transmission electron microscope (TEM), Fourier-transform infrared (FTIR), X-ray diffraction pattern (XRD) and X-ray photoelectron spectroscopy (XPS). This comparative characterization revealed that both OFL and ENR were initially adsorbed on to the surface of Fe NPs, and then Fe NPs were corroded to form Fe3O4 via sequential Fenton-like oxidation. Initial kinetic adsorption data best fit a pseudo-second-order kinetic model (R2 ≥ 0.913), while the subsequent Fenton-like oxidation process best fit a pseudo first-order model (R2 ≥ 0.964). Oxidation products detected by the high performance liquid chromatography mass spectrometry (HPLC-MS) confirmed that overall removal mechanism of both OFL and ENR involved oxidative degradation. Finally, the recycling and application in real wastewaters of sequential Fenton-like oxidation of the Fe/H2O2 system was evaluated.

Chiral Derivatives of Xanthones with Antimicrobial Activity.

According to the World Health Organization, the exacerbated use of antibiotics worldwide is increasing multi-resistant infections, especially in the last decade. Xanthones are a class of compounds receiving great interest in drug discovery and development that can be found as natural products or obtained by synthesis. Many derivatives of xanthones are chiral and associated with relevant biological activities, including antimicrobial. The aim of this review is to compile information about chiral derivatives of xanthones from natural sources and their synthesized examples with antimicrobial activity.

Distribution of Multi-Resistant Bacterial Isolates from Clinical Specimens in a Hospital Environment of Kingdom of Saudi Arabia

: Objective: The problem of antimicrobial resistance in Kingdom of Saudi Arabia is an emerging problem where the complete elimination of antimicrobial resistance is impossible due to the irrational use of antibiotics worldwide and in Saudi Arabia. Thus, the present study was undertaken to determine the prevalence of bacterial pathogens and to assess the multidrug resistant (MDR) strains to different antibiotics in Aseer Region, Kingdom of Saudi Arabia. Method: A retrospective analysis of 163 subjects diagnosed with variable infections during the period of February – May 2015. The study was conducted at a 500 bedded tertiary health care center. The data were collected from microbiological laboratory and patient case sheet. The bacterial isolates are categorized as sensitive or resistant based on the zone of inhibition of antibiotics. Results: Total of 15 different strains of gram positive and negative were isolated where, a urine specimen was found to have the highest number of bacterial isolates (28.8 %) and intensive care unit (ICU) had more number of isolates. Among 46 antibiotics tested, only 12 antibiotics were included in the analysis. Almost, most of the gram positive and gram negative bacterial isolates had resistance to more than three antimicrobials, which satisfies the criteria to call them as multidrug resistant bacterial isolates. Conclusion: Overall prevalence of antibiotic resistance to the commonly used antibiotics was high in the bacterial isolates selected in our study center, which warrants the infection control to reduce resistance.Key words: Resistance, Prevalence, Antimicrobials, Bacterial isolates, Saudi Arabia.

Antibiotics - In Which Fields is there Need for Action?

For decades, antibiotics have been utilized successfully to treat infectious diseases. As part of a natural process, resistance mechanisms evolved in bacteria rendering some of these antibiotics ineffective. A significant increase in the use of antibiotics worldwide has greatly accelerated this process. As a result, treatment of many infectious diseases such as tuberculosis or gonorrhea has become increasingly difficult and nosocomial infections are causing great problems in health care systems. Many action plans and counter-measures have been developed but are seldom put into action and fail to address all problems related to antibiotic resistance. To ensure that antibiotics will remain a reliable option for treating infectious diseases, targeted action is needed in various fields.

Antibacterial activity of Pinus elliottii and its major compound, dehydroabietic acid, against multidrug-resistant strains.

Antibiotic-resistant bacteria have emerged from the widespread use of antibiotics worldwide and have prompted the search for new sources of antimicrobial substances. Pinus spp. contain several bioactive compounds consisting mainly of terpenes, terpenoids and some other aromatic and aliphatic constituents. These compounds exert important biological effects, and pine oils have found wide application in the industry. In the present study, we have evaluated the potential activity of the resin-oil of Pinus elliottii and its major compound dehydroabietic acid (DA) against multiresistant bacteria by MIC, minimum bactericidal concentration and time-kill assays. The MIC of the resin-oil of P. elliottii varied between 25 and 100 µg ml(-1). As for DA, the MIC and minimum bactericidal concentration varied between 6.25 and 50 and between 6.25 and 100 µg ml(-1), respectively. The time-kill assay conducted with DA at 6.25 µg ml(-1) evidenced bactericidal activity against Staphylococcus epidermidis (American Type Culture Collection 14990) within 24 h. On the basis of these results, the resin-oil of P. elliottii and its major compound DA play an important part in the search for novel sources of agents that can act against multiresistant bacteria.

Influence of nine antibiotics on key secondary metabolites and physiological characteristics in Triticum aestivum: Leaf volatiles as a promising new tool to assess toxicity

Extensive worldwide use of antibiotics has resulted in significant diffuse pollution of antibiotics in environment, but understanding the effects of many important antibiotics on plant physiological activity is still limited, especially at realistic environmental concentrations of antibiotics. To gain insight into influences of different antibiotics on plant performance and identify the most promising traits for fast assessment of toxicity, we studied impacts of nine antibiotics (amoxicillin, ampicillin, penicillin G, ceftazidime, ceftriaxone, tetracycline, doxycycline, ciprofloxacin and erythromycin) on foliage photosynthesis, photosynthetic pigment content and emissions of secondary volatile metabolites in wheat (Triticum aestivum L. cv. “Lovrin”). The antibiotics were applied at concentrations of 0.5mgL−1 or 1.5mgL−1 either by watering for one week (0.5L solution) or for two weeks (1L solution) with given solution. Net assimilation rate was inhibited most strongly by ciprofloxacin and cephalosporins, but the inhibition was mainly due to reductions in stomatal conductance. Photosynthetic electron transport rate was affected by penicillins, cephalosporins and tetracyclines. Contents of photosynthetic pigments, chlorophylls and carotenoids, were most strongly reduced in treatments with tetracyclines, ciprofloxacin and erythromycin. The magnitude of plant photosynthetic and pigment responses generally increased with increasing the antibiotics’ dose, but the overall effects were moderate, 10–20 percent in most cases. Emissions of the lipoxygenase pathway products (LOX, green leaf volatiles) were most sensitive indicators of antibiotic treatments. LOX emissions were increased by five to six fold in response to antibiotic treatments and the emissions were quantitatively associated with the treatment dose. Monoterpene emissions were also strongly enhanced by antibiotic treatments, but the dose dependence was weaker. These data collectively suggest that analysis of leaf volatiles can provide a novel sensitive assay to gauge the toxicity of different antibiotics.