Genotyping Characteristics of Human Fecal Escherichia coli and Their Association with Multidrug Resistance in Miyun District, Beijing / 生物医学与环境科学（英文）

OBJECTIVE@#To explore the genotyping characteristics of human fecal Escherichia coli( E. coli) and the relationships between antibiotic resistance genes (ARGs) and multidrug resistance (MDR) of E. coli in Miyun District, Beijing, an area with high incidence of infectious diarrheal cases but no related data.@*METHODS@#Over a period of 3 years, 94 E. coli strains were isolated from fecal samples collected from Miyun District Hospital, a surveillance hospital of the National Pathogen Identification Network. The antibiotic susceptibility of the isolates was determined by the broth microdilution method. ARGs, multilocus sequence typing (MLST), and polymorphism trees were analyzed using whole-genome sequencing data (WGS).@*RESULTS@#This study revealed that 68.09% of the isolates had MDR, prevalent and distributed in different clades, with a relatively high rate and low pathogenicity. There was no difference in MDR between the diarrheal (49/70) and healthy groups (15/24).@*CONCLUSION@#We developed a random forest (RF) prediction model of TEM.1 + baeR + mphA + mphB + QnrS1 + AAC.3-IId to identify MDR status, highlighting its potential for early resistance identification. The causes of MDR are likely mobile units transmitting the ARGs. In the future, we will continue to strengthen the monitoring of ARGs and MDR, and increase the number of strains to further verify the accuracy of the MDR markers.

Antibióticos innovadores contra la farmacorresistencia bacteriana obtenido por tecnología de edición genética CRISPR/Cas9 / Innovative antibiotics against bacterial drug resistance obtained by CRISPR/cas9 gene editing technology

Introducción: El aumento de la resistencia a los antimicrobianos constituye actualmente una peligrosa amenaza para la salud. Ante este problema global de falta de antimicrobianos, es perentorio intervenir de forma coordinada e idear fórmulas para incentivar la investigación a nivel internacional. Objetivo: Realizar una revisión actualizada sobre las causas y mecanismos de la resistencia a los antibióticos y la adaptación del sistema CRISPR/Cas para el desarrollo de innovadores antimicrobianos como parte esencial de una estrategia altamente específica en el tratamiento de infecciones producidas por bacterias resistentes. Métodos: Se realizó una revisión documental, se empleó la bibliografía nacional e internacional especializada publicada en los últimos 5 años. Se utilizó el motor de búsqueda Google Académico y se consultaron artículos de libre acceso en las bases de datos Pubmed, SciELO, LILACS, CUMED y HINARI, en el período comprendido entre marzo de 2020 hasta el mes de enero de 2021. Se revisaron un total de 41 artículos. Las consultas se hicieron en inglés y español. Para la búsqueda se tuvo en cuenta las palabras clave: eligobióticos; resistencia a antibióticos; CRISPR/Cas. Resultados: La evidencia recopilada sustenta que muchas enfermedades son inducidas por alteraciones del equilibrio de la microbiota humana y la técnica de edición genética CRISPR/Cas permitirá el desarrollo de novedosos antibióticos como los eligobióticos que eliminarán las bacterias patógenas multirresistentes y dejarán intacto el microbioma. Conclusiones: el esclarecimiento de los enigmas de la microbiota y su diseño con terapia génica permitirán el progreso de innovadores antibióticos con empleo del sistema CRISPR/Cas que ineludiblemente modificarán la práctica médica para siempre(AU)

Introduction: The increase in antimicrobial resistance is currently a dangerous threat to health. Faced with this global problem of lack of antimicrobials, it is imperative to intervene in a coordinated manner and devise formulas to encourage research at the international level. Objective: To review on the update causes and mechanisms of antibiotic resistance and the adaptation of CRISPR/Cas system for the development of innovative antimicrobials as an essential part of a highly specific strategy in the treatment of infections caused by resistant bacteria. Methods: A documentary review was carried out in the specialized national and international bibliography published in the last 5 years. Google Scholar search engine was used and free access articles were consulted in Pubmed, SciELO, LILACS, CUMED and HINARI databases, from March 2020 to January 2021. A total of 41 articles were retrieved. The consultations were made in English and Spanish. For the search, we took into account the keywords eligobiotics, antibiotic resistance, CRISPR/Cas. Results: The reviewed evidence supports that many diseases are induced by alterations in the balance of the human microbiota; and CRISPR/Cas gene editing technique will allow the development of novel antibiotics such as eligobiotics that will eliminate multi-resistant pathogenic bacteria and leave the microbiome intact. Conclusions: The clarification of the enigmas of the microbiota and its design with gene therapy will allow the progress of innovative antibiotics using CRISPR/Cas system that will inevitably change medical practice forever(AU)

Prevention and control of antimicrobial resistance using CRISPR-Cas system: a review / 生物工程学报

Bacterial multi-drug resistance (MDR) is a global challenge in the fields of medicine and health, agriculture and fishery, ecology and environment. The cross-region spread of antibiotic resistance genes (ARGs) among different species is one of the main cause of bacterial MDR. However, there is no effective strategies for addressing the intensifying bacterial MDR. The CRISPR-Cas system, consisting of clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR associated proteins, can targetedly degrade exogenous nucleic acids, thus exhibiting high application potential in preventing and controlling bacterial MDR caused by ARGs. This review briefly introduced the working mechanism of CRISPR-Cas systems, followed by discussing recent advances in reducing ARGs by CRISPR-Cas systems delivered through mediators (e.g. plasmids, bacteriophages and nanoparticle). Moreover, the trends of this research field were envisioned, providing a new perspective on preventing and controlling MDR.

Root canal microbiota as an augmented reservoir of antimicrobial resistance genes in type 2 diabetes mellitus patients

Abstract Antimicrobial resistance is a global public health problem. Root canal microbiota associated with apical periodontitis represents a well-known reservoir of antimicrobial resistance genes (ARGs). However, the effect of type 2 diabetes mellitus (T2DM) in this reservoir is unknown. This study aimed to establish if root canal microbiota associated with apical periodontitis in T2DM patients is an augmented reservoir by identifying the prevalence of nine common ARGs and comparing it with the prevalence in nondiabetic patients. Methodology This cross-sectional study included two groups: A T2DM group conformed of 20 patients with at least ten years of living with T2DM and a control group of 30 nondiabetic participants. Premolar or molar teeth with pulp necrosis and apical periodontitis were included. A sample was collected from each root canal before endodontic treatment. DNA was extracted, and ARGs were identified by polymerase chain reaction. Results tetW and tetM genes were the most frequent (93.3 and 91.6%, respectively), while ermA was the least frequent (8.3%) in the total population. The distribution of the ARGs was similar in both groups, but a significant difference (p<0.005) was present in ermB, ermC, cfxA, and tetQ genes, being more frequent in the T2DM group. A total of eighty percent of the T2DM patients presented a minimum of four ARGs, while 76.6% of the control group presented a maximum of three. Conclusions Root canal microbiota associated with apical periodontitis in T2DM patients carries more ARGs. Therefore, this pathological niche could be considered an augmented reservoir.

Environmental risks of antibiotics in soil and the related bioremediation technologies / 生物工程学报

Antibiotics are widely used and prevalently distributed in the environment. The issue of antibiotic resistance genes has posed a huge threat to the global public health. Soil is an important sink of antibiotics in the environment. Antibiotic exposure may introduce adverse effects on soil organisms, and bring indirect but potential risks to human health. Therefore, it is urgent to take actions to remediate antibiotics-contaminated soil. This review summarized effects of antibiotics on phenotype growth of plants, physiological characteristics and community structure of animals, composition and structure of microbial communities, and transmission of antibiotic resistance genes among organisms in soil. Additionally, the potential and prospects of employing antibiotic-resistant soil plants, animals, microorganisms, and their combinations to treat antibiotics-contaminated soil were illustrated. Last but not least, the unaddressed issues in this area were proposed, which may provide insights into relevant research directions in the future.

Resistencia antibiótica: el papel del hombre, los animales y el medio ambiente / Antibiotic resistance: the role of man, animals and the environment

RESUMEN Los microorganismos, especialmente las bacterias, están distribuidos por todo el mundo, desde el suelo, los mares y los ríos hasta el sistema digestivo de los animales y los seres humanos; por lo tanto, las bacterias mantienen una interacción constante con los compuestos utilizados por los seres humanos y los animales como los antibióticos, y con otros microorganismos que pueden ser de la misma especie o de diferentes géneros taxonómicos; esta interacción podría dar lugar a una presión selectiva sobre las bacterias en el medio ambiente y promover el intercambio de material genético, lo que llevaría a una propagación global de la resistencia a los antibióticos y a una afectación mundial de la salud. En este contexto, esta revisión tiene por objeto ofrecer una visión general del papel de los seres humanos, los animales y el medio ambiente en la resistencia bacteriana, con énfasis en los procesos en el suelo y los medios acuáticos y los efectos sobre la salud humana.

ABSTRACT Microorganisms, especially bacteria, are distributed throughout the world, from the soil, seas and rivers to the digestive system of animals and humans. Therefore, the bacteria maintain a constant interaction with compounds used by humans and animals, such as antibiotics, and with other microorganisms that may be of the same species or of different taxonomic genera. In addition, this interaction could lead to selective pressure on bacteria in the environment and promote the exchange of genetic material, which would allow to a global spread of antibiotic resistance and thus a worldwide affectation on health. In this context, the present review aims to provide an overview of the role of humans, animals and the environment in bacterial resistance, with emphasis on soil and aquatic processes and effects on human health.

Overview of antibiotic resistance genes database / 生物工程学报

The discovery of antibiotics is a big revolution in human history, and its clinical application has saved countless lives. However, with the widespread and abuse of antibiotics, many pathogens have developed resistance, and even "Super Bacteria" resistance to multiple drugs have evolved. In the arms race between humans and pathogens, humans are about to face a situation where no medicine is available. Research on microbial antibiotic resistance genes, resistance mechanisms, and the spread of resistance has attracted the attention of many scientific researchers, and various antibiotic resistance gene databases and analysis tools have emerged. In this review, we collect the current databases that focus on antibiotics resistance genes, and discuss these databases in terms of database types, data characteristics, antibiotics resistance gene prediction models and the types of analyzable sequences. In addition, a few gene databases of anti-metal ions and anti-biocides are also involved. It is believed that this summary will provide a reference for how to select and use antibiotic resistance gene databases.

Antibiotic resistance of Enterococcus faecalis from persistent endodontic infections / Resistencia antibiótica de Enterococcus faecalis provenientes de infecciones endodónticas persistentes

Enterococci are important nosocomial pathogens due to their intrinsic multiresistance and the acquisition of new antibiotic resistance genes (ARG). Enterococcus faecalis has been shown to be one of the main pathogens in persistent endodontic infections, therefore, the main objective of this study was to evaluate the phenotype and resistance genotype of strains of E. faecalis isolated from teeth with persistent endodontic lesions, to the most commonly prescribed antibiotics in dentistry. Thirteen strains of E. faecalis of different pulsotype were analyzed to evaluate the susceptibility to antibiotics, amoxicillin, amoxicillin/clavulanic acid, tetracycline, erythromycin and metronidazole, using the Epsilometer test (E- test) and the presence of beta-lactamases with nitrocefin test. Finally, the detection of ARG was performed with a molecular polymerase chain reaction (PCR) technique and confirmed by the sequencing of the amplification products. Fisher's exact test was used, using 95 % confidence. Regarding the phenotype of resistance, the evaluated strains, independent of the pulsotype, were totally resistant to the action of metronidazole. Antibiotics with higher minimum inhibitory concentration (MIC) after metronidazole include tetracycline and erythromycin. In contrast, lower MIC are applied to the combination of amoxicillin with clavulanic acid. The nitrocefin test was positive only in one strain. Genotypically, two genetically distant strains isolated from a single patient, presented a genotype of resistance to erythromycin, determined by the presence of the ermB gene. No statistically significant relationship was found between phenotypic resistance and the presence of ARG in relation to erythromycin (p> 0.05). It was concluded that isolates of E. faecalis from persistent endodontic infections showed phenotypes of resistance to several antimicrobial agents, all of which were susceptible to amoxicillin/clavulanic acid. Periodic evaluation of susceptibility to antibiotics is suggested as an important practice for the surveillance of antibiotic resistance in oral strains.

Los enterococos son importantes patógenos nosocomiales debido a su multi resistencia intrínseca y la adquisición de nuevos genes de resistencia a los antibióticos (ARG). Enterococcus faecalis es uno de los principales patógenos en infecciones endodónticas persistentes, por lo tanto, el objetivo principal de este estudio fue evaluar el fenotipo y el genotipo de resistencia de cepas de E. faecalis aisladas de dientes con lesiones endodóncicas persistentes, a los antibióticos comúnmente recetados en odontología. Se analizaron 13 cepas de E. faecalis de diferentes pulsotipos para evaluar la susceptibilidad a los antibióticos, amoxicilina, amoxicilina / ácido clavulánico, tetraciclina, eritromicina y metronidazol, utilizando la prueba de Epsilometría (E-test) y la presencia de beta-lactamasas con prueba de nitrocefina. Finalmente, la detección de ARG se realizó con una técnica molecular de reacción en cadena de la polimerasa (PCR) y se confirmó mediante la secuenciación de los productos de amplificación. Se utilizó la prueba exacta de Fisher, con un 95 % de confianza. En cuanto al fenotipo de resistencia, las cepas evaluadas, independientes del pulsotipo, fueron totalmente resistentes a la acción del metronidazol. Los antibióticos con los valores más altos de concentración mínima inibitoria (CMI) después del metronidazol incluyen tetraciclina y eritromicina. En contraste, las CMI mas bajas se aplican a la combinación de amoxicilina con ácido clavulánico. La prueba de nitrocefina fue positiva solo en una cepa. Genotípicamente, dos cepas distantes genéticamente, aisladas de un mismo paciente fueron positivas para el gen ermB. No se encontró una relación estadísticamente significativa entre la resistencia fenotípica y la presencia de ARG en relación con la eritromicina (p> 0,05). Se concluyó que los aislamientos de E. faecalis de infecciones endodónticas persistentes mostraron fenotipos de resistencia a varios agentes antimicrobianos, todos los cuales fueron susceptibles a amoxicilina / ácido clavulánico. Se sugiere una evaluación periódica de la susceptibilidad a los antibióticos como una práctica importante para la vigilancia de la resistencia a los antibióticos en las cepas orales.

Resistencia microbiana desde una perspectiva metagenómica / Microbial resistance from one metagenomic perspective

Resumen Objetivo. La finalidad de esta revisión es abarcar la temática relacionada con los genes de resistencia a antibióticos, sus orígenes, reservorios y movimientos en los diferentes hábitats mediante la metagenómica funcional que permite aislar, identificar y analizar estos genes, así como el impacto que tienen en salud pública. Durante los últimos años se ha visto un gran avance en la microbiología, una de las grandes limitaciones a las que se venían enfrentado los microbiólogos era no poder acceder a la totalidad de los microorganismos que habitan el planeta. Gracias al desarrollo de diferentes disciplinas como la metagenómica se ha logrado tener el acceso a estos microorganismos. Metodología. La importancia de la metagenómica en la resistencia microbiana radica en que, actualmente, solo el 1 % de los microorganismos que habitan el suelo pueden ser estudiados por técnicas convencionales de microbiología, quedando alrededor del 99 % de estos sin estudiar. Al mitigar este gran inconveniente, la metagenómica permite el estudio de la microbiota del suelo en su totalidad generando nuevo conocimiento e información relevante en diferentes campos científicos. Resultados. Mediante la metagenómica funcional se ha podido determinar que el suelo puede ser un posible reservorio de determinantes de resistencia microbiana, debido a que la microbiota que allí habita contiene en su material genético genes de resistencia a antibióticos que confieren resistencia a un amplio espectro de antibióticos utilizados en terapia humana de forma indiscriminada y además tienen todos los mecanismos de resistencia conocidos, algunos de estos genes son generados por presión selectiva ante diferentes agentes presentes en su medio y otros son genes constitutivos que cumplen con funciones significativas en su hábitat. El gran impacto que tienen estos hallazgos está dado en que pueden representar un posible riesgo en salud pública si se adquieren por los patógenos humanos.

Abstract Objective. The purpose of this review is to cover the issues related to antibiotic resistance genes, their origins, reservoirs and movements in different habitats through functional metagenomics that allows to isolate, identify and analyze these genes, as well as the impact they have on health public. During the last years a great advance in the microbiology has been seen, one of the great limitations to which the microbiologists had been facing was not being able to have access to the totality of the microorganisms that inhabit the planet. Thanks to the development of different disciplines such as metagenomics, access to these microorganisms has been achieved. Method. The importance of metagenomics in microbial resistance lies in the fact that currently only 1 % of the microorganisms that inhabit the soil can be studied by conventional microbiology techniques, leaving about 99 % of these without studying, the metagenomics by mitigating this great disadvantage allows the study of the soil microbiota in its entirety generating new knowledge and relevant information in different scientific fields. Results. Through functional metagenomics it has been possible to determine that the soil can be a possible reservoir of determinants of microbial resistance, because the microbiota that live there contain in their genetic material antibiotic resistance genes that confer resistance to a broad spectrum of antibiotics used in human therapy indiscriminately and also have all known mechanisms of resistance, some of these genes are generated by selective pressure against different agents present in their environment and others are constitutive genes that fulfill significant functions in their habitat. The great impact of these findings is that they can represent a possible public health risk if they were acquired by human pathogens.

Antibiotic resistance in environment of animal farms / 生物工程学报

World Health Organization has recognized antibiotic resistance is one of the serious threats to public health and food-safety in the 21st century. Recently, the antibiotic resistance gene (ARG) has been widely considered as a new pollutant. Now, many studies suggested that animal farm is one of the major reservoirs of ARGs. Antibiotic resistance bacteria and antibiotic resistance genes enter the environment along with animal excrement, accelerating the spread of ARGs in the environment. In the livestock and poultry breeding environment, ARGs and antibiotic resistant bacteria could be transmitted to humans through the food chain, water or air, posing a great threat to public health. This review highlights the prevalence of antibiotic resistant bacteria and antibiotic resistant genes in livestock-breeding environment, the retention and spread of ARGs and the method used to study the antibiotic resistance, which will provide certain support for risk assessment of antimicrobial resistance in food animal breeding environment.

Bacterial resistance influences intestinal flora and host immune regulation / 生物工程学报

Overuse of antibiotics in aquaculture, husbandry and healthcare has led to antibiotics residues in the enviuronment and the generation of antibiotic resistant bacteria that can be transferred into the human gut through food chain. Based on literatures, we reviewed the influence of bacterial resistance on intestinal flora and related immune regulation. Taking the source of antibiotic resistance to human intestinal flora as an entry point, we addressed the structure of human intestinal flora and the composition of drug resistance genes after exposure to pollutants. Moreover, we discussed the relationship among changes of intestinal flora, antibiotic resistance genes and immunomodulation related diseases. Last, we also indicated future research needs.

Study on the transfer mechanism and destructive law of the bacterial antibiotic resistance genes disinfected by chlorination / 中华预防医学杂志

Objective@#To study the response of Escherichia coli (E. coli) HB101 (plasmid pUC19) and its carried antibiotic resistance genes to the process of cholorination under different environmental conditions.@*Methods@#The E. coli strain was reacted with sodium hypochlorite at the concentration of 0.5, 0.75, 1.00, and 0.55 mg/L, then the residual chlorine and the colonies were detected at the 0.25, 1, 2, 5, 10, 20, and 30 min of the reaction, respectively. The first order disinfection kinetic model and EFH model were used to evaluate the inactivation effect of E. coli (plasmid pUC19) treated by sodium hypochlorite, while the plasmid pUC19 and antibiotic resistance gene ampr were detected by PCR method. Besides, the logarithm of Ct (residual chlorine in t) under different concentration were calculated.@*Results@#The temperature and pH value played important roles on the inactivation of E. coli and elimination of plasmid pUC19 and ampr under the function of sodium hypochlorite. The Ct value needed for 5-log of E.coli HB101(pUC19) inactivation at 4, 20, 36 ℃ was 11.92, 10.28, 7.67, respectively, and when the pH was in 6.0, 7.0, 8.0, with chloride concentration were 0.75, 0.70, 0.55 mg/L, the Ct value needed for reached to 6.68, 10.28, 15.73 min·mg/L. At pH 7.2 condition, when the temperature was 4, 20, 36 ℃, and chloride concentration were 9, 5, 3 mg/L.The required Ct values to completely destroy the transformation function of free antibiotic resistant plasmids were 36.11, 34.17,16.09 min·mg/L. Sodium hypochlorite disinfection can release free ampr gene and even the transformed plasmid pUC19, and pollute the water body. Only when the Ct value reached 903.03 min·mg/L, the complete ampr gene can be destroyed which was far more exceed the bacterial lethal Ct value.@*Conclusion@#Even if all the antibiotic resistant bacteria were inactivated, the antibiotic resistant plasmids or genes might still maintain complete with the transformable function, which may result in new potential risks of waterborne diseases.

State-of-the-art status on airborne antibiotic resistant bacteria and antibiotic resistance genes / 中华预防医学杂志

The world is facing more deaths due to increasing antibiotic-resistant bacterial infections and the shortage of new highly effective antibiotics, however the air media as its important transmission route has not been adequately studied. Based on the latest literature acquired in this work, we have discussed the state-of-the-art research progress of the concentration, distribution and spread of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in different environmental air media, and also analyzed some future prevention and control measures. The large use of antibiotics in the medical settings and animal husbandry places has resulted in higher abundances of ARB and ARGs in the relevant and surrounding atmosphere than in urban and general indoor air environments. ARGs can be spread by adhering to airborne particles, and researchers have also found that air media contain more abundant ARGs than other environmental media such as soil, water and sediment. It was suggested in this review that strengthening the monitoring, study on spreading factors and biological toxicity, and also research and development on pathogen accurate diagnosis and new green antibiotic are expected to help effectively monitor, prevent and control of the impacts of airborne resistant bacteria and resistance genes on both human and ecologies.

Study of ocular surface macro genome in dry eye patients / 眼科新进展

Objective To investigate the difference in ocular surface microbiota between dry eye patients and healthy subjects,and discuss the role of microbiota in dry eye.Methods Twenty cases of dry eye patients and 90 cases of healthy subjects were collected in the PLA General Hospital and Zhongshan Ophthalmic Center.The samples of conjunctiva impression cytology were collected from all subjects,and then metagenomic shotgun sequencing was performed following the DNA extraction.The differences in alpha diversity and metabolic pathways of the ocular surface microbiota between dry eye patients and healthy subjects were evaluated.Results There was no significant difference in alpha diversity of the microbial community between dry eye patients and healthy subjects (P =0.13).However,an increase of 15 species and a decrease of 10 species were detected on the ocular surface of dry eye patients.The enriched antibiotic resistance genes in dry eye patients were more than healthy subjects.Conclusion Although the alpha diversity of the microbial community on ocular surface between dry eye patients and healthy subjects are not distinguishable,a significant difference could be found in relative abundance and metabolic pathways,suggest that these specific microbiome may be related to the pathogenesis and disease progression of dry eye.

Antibiotic resistance in lactic acid bacteria isolated from some pharmaceutical and dairy products

A total of 244 lactic acid bacteria (LAB) strains were isolated from 180 dairy and pharmaceutical products that were collected from different areas in Minia governorate, Egypt. LAB were identified phenotypically on basis of morphological, physiological and biochemical characteristics. Lactobacillus isolates were further confirmed using PCR-based assay. By combination of phenotypic with molecular identification Lactobacillus spp. were found to be the dominant genus (138, 76.7%) followed by Streptococcus spp. (65, 36.1%) and Lactococcus spp. (27, 15%). Some contaminant organisms such as (Staphylococcus spp., Escherichia coli, Salmonella spp., mould and yeast) were isolated from the collected dairy samples but pharmaceutical products were free of such contaminants. Susceptibility of LAB isolates to antibiotics representing all major classes was tested by agar dilution method. Generally, LAB were highly susceptible to Beta-lactams except penicillin. Lactobacilli were resistant to vancomycin, however lactococci and streptococci proved to be very susceptible. Most strains were susceptible to tetracycline and showed a wide range of streptomycin MICs. The MICs of erythromycin and clindamycin for most of the LAB were within the normal range of susceptibility. Sixteen Lactobacillus,8 Lactococcus and 8 Streptococcus isolates including all tetracycline and/or erythromycin resistant strains were tested for the presence of tetracycline and/or erythromycin resistant genes [tet(M) and/or erm(B)]. PCR assays shows that some resistant strains harbor tet(M) and/or erm(B) resistance genes.

Occurrence and variations of five classes of antibiotic resistance genes along the Jiulong River in southeast China.

Antibiotic resistance genes (ARGs) are emerging microbial hazards threatening human health. Many factors, including urban and agricultural activities and water environment changes, can significantly impact the variations of ARGs. An investigation on the occurrence and variations of ARGs in the Jiulong River was done in this study. The water samples were collected from 16 sites ranging from the upper branch to the river mouth of the Jiulong River, in both low- and high-flow periods. Eleven ARG families were tested and quantified by real-time PCR (SYBR Green) methods, and detection assays were conducted for tetA, tetG, aacC1, strA, ermB, cmlA5, vanA, dfrA1, sulII, blaTEM-1 and blaoxa-1 genes. Results showed that nine ARG families were found, then the swine industry and urban activities, including sewage discharge, might be responsible for the high levels of concentrations and relative abundances of ARGs, and the increase of salinity might decrease the relative abundances of ARGs. In addition, some ARG abundances were significantly correlated to the concentrations of NH4+ and PO4-3, particularly in the high-flow period. The human activities were important sources for ARGs in the Jiulong River, which have already become a threat to the safety of drinking water for the nearby cities.

Antibiotic resistance genes & susceptibility patterns in staphylococci.

Background & objectives: This study was carried out to evaluate the association between the antibiotic susceptibility patterns and the antibiotic resistance genes in staphylococcal isolates obtained from various clinical samples of patients attending a teaching hospital in Hatay, Turkey. Methods: A total of 298 staphylococci clinical isolates were subjected to antimicrobial susceptibility testing. The genes implicated in resistance to oxacillin (mecA), gentamicin (aac(6’)/aph(2”), aph(3’-IIIa, ant(4’)-Ia), erythromycin (ermA, ermB, ermC, and msrA), tetracyclin (tetK, tetM), and penicillin (blaZ) were amplified using multiplex PCR method. Results: Methicillin resistance rate among 139 Staphlococcus aureus isolates was 16.5 and 25.9 per cent of S. aureus carried mecA gene. Of the 159 CoNS isolates, methicillin resistance rate was 18.9 and 29.6 per cent carried mecA gene. Ninety four isolates identified as gentamicin resistant phenotypically, contained at least one of the gentamicin resistance genes [aac(6’)/aph(2”), aph(3’)-IIIa, ant(4’)-Ia], 17 gentamicin-susceptible isolates were found as positive in terms of one or more resistance genes [aac(6’)/aph(2”), aph(3’)-IIIa, ant(4’)-Ia] by multiplex PCR. A total of 165 isolates were resistant to erythromycin, and contained at least one of the erythromycin resistance genes (ermA, ermB, ermC and msrA). Phenotypically, 106 staphylococcal isolates were resistant to tetracycline, 121 isolates carried either tetK or tetM or both resistance genes. The majority of staphylococci tested possessed the blaZ gene (89.9%). Interpretation & conclusions: The present results showed that the phenotypic antibiotic susceptibility patterns were not similar to those obtained by genotyping done by multiplex PCR. Rapid and reliable methods for antibiotic susceptibility are important to determine the appropriate therapy decisions. Multiplex PCR can be used for confirmation of the results obtained by conventional phenotypic methods, when needed.