Extracellular DNA refers to DNA fragments existing outside the cell, originating from various cell release mechanisms, including active secretion, cell lysis, and phage-mediated processes. Extracellular DNA serves as a vital environmental biomarker, playing crucial ecological and environmental roles in water bodies. This review is summarized the mechanisms of extracellular DNA release, including pathways involving cell lysis, extracellular vesicles, and type IV secretion systems. Then, the extraction and detection methods of extracellular DNA from water, soil, and biofilm are described and analyzed. Finally, we emphasize the role of extracellular DNA in microbial community systems, including its significant contributions to biofilm formation, biodiversity through horizontal gene transfer, and electron transfer processes. This review offers a comprehensive insight into the sources, distribution, functions, and impacts of extracellular DNA within aquatic environments, aiming to foster further exploration and understanding of extracellular DNA dynamics in aquatic environments as well as other environments.

Substituted polycyclic aromatic hydrocarbons (SPAHs) are a type of emerging pollutant that widely exist in the environment, which also exhibit carcinogenicity, mutagenicity, and teratogenicity. These pollutants belong to toxic pollutants because of their similar structures to polycyclic aromatic hydrocarbons (PAHs). Their environmental behavior and ecological risk have attracted increasing attention. Based on a literature review, we found a new breakthrough in the source, distribution, behavior, and risk of SPAHs with comparison to traditional pollutants PAHs. This paper reviewed the current research progress on the environmental occurrence and photochemical behavior of SPAHs. Their sources, formation mechanisms, and distribution characteristics in the multimedia environment were highlighted, and the photochemical transformation kinetics, pathways, and affecting factors of SPAHs in water, ice, and other media were discussed. Furthermore, the research prospects about the environmental behavior and risk of SPAHs were proposed.

In recent years, antibiotics have been listed as a new class of environmental pollutants. Tetracycline antibiotics (TCs) used in human medical treatment, animal husbandry and agricultural production are the most widely used antibiotics. Due to their wide range of activities and low cost, their annual consumption is increasing. TCs cannot be completely metabolized by humans and animals. They can be abused or overused, causing the continuous accumulation of TCs in the ecological environment and potential negative effects on non-target organisms. These TCs may spread into the food chain and pose a serious threat to human health and the ecology. Based on the Chinese environment, the residues of TCs in feces, sewage, sludge, soil and water were comprehensively summarized, as well as the potential transmission capacity of air. This paper collected the concentrations of TCs in different media in the Chinese environment, contributing to the collection of a TC pollutant database in China, and facilitating the monitoring and treatment of pollutants in the future.

Over the last decade, microplastics (MPs, plastic particles <5 mm) as emerging contaminants have received a great deal of international attention, not only because of their continuous accumulation in both marine and terrestrial environment, but also due to their serious threats posed to the environment. Voluminous studies regarding sources, distribution characterization, and fate of MPs in the different environmental compartments (e.g., marine, freshwater, wastewater, and soil) have been reported since 2004, whereas MPs pollution in unique marine ecosystems (e.g., coastal mangrove habitat) receives little scientific attention. Mangrove ecosystem, an important buffer between the land and the sea, has been identified as a potential sink of MPs caused by both marine and land-based activities. Moreover, the source and distribution characteristics of MPs in this ecosystem are significantly different from other coastal habitats, mainly owing to its unique features of high productivity and biomass. With the impetus to provide a more integrated view of MPs pollution in mangrove habitats, a literature review was conducted based on the existing studies related to this topic. This is the first review to present the current state of MPs pollution in mangrove ecosystems, specially including (i) the possible sources of MPs in mangrove areas and their pathways entering into this habitat; (ii) MPs pollution in the different mangrove compartments (including surface seawater, sediments, and biotas); and (iii) factors influencing MPs distribution in mangrove areas. Toward that end, the research gaps are proposed to guide for future research priorities.

OBJECTIVE: Neonatal sepsis (NS) has no specific clinical manifestations and blood culture analysis requires a long period of time. Knowledge of prevalent bacterial isolates and their antibiotic susceptibility is crucial when choosing an empirical therapy to decrease morbidity and mortality. This literature review summarizes the distribution characteristics and antimicrobial resistance of bacterial pathogens associated with bloodstream infections in Chinese neonates, and thus serves as a reference for pediatricians.
METHODS: The full-text journal database, CNKI, was searched using the key words \"neonatal\", \"sepsis\", and \"bacterial pathogen\" to retrieve relevant literature published from 2016 up to April 2018. The following data were extracted from the selected papers: title, pathogen collection time, care unit name, province (city), distribution of bacterial pathogens among bloodstream infections, and antimicrobial resistance of major pathogens.
RESULTS: A total of 86 articles were searched, of which 30 complied with the study requirements and thus were included in the review; all were retrospective studies. The articles covered a total of 4098 bacterial strains from 24 cities (2494 Gram-positive bacteria, 1429 Gram-negative bacteria, 176 fungi). Among the Gram-positive bacteria, the four pathogens with the highest detection rates were coagulase-negative staphylococci (CoNS) (40.23%), Streptococci (6.81%), Enterococci (6.10%), and Staphylococcus aureus (S. aureus) (5.15%); among the Gram-negative bacteria, Klebsiella (14.52%), Escherichia coli (12.12%), Enterobacter cloacae (1.90%), and Pseudomonas (1.41%) had the highest detection rates. The detection rate of Candida and other fungi was 4.29%. Among the pathogens with high clinical detection rates, S. epidermidis and S. aureus are highly resistant to both erythromycin and penicillin. Antibacterial drugs with high efficacy for both S. epidermidis and S. aureus include vancomycin, ciprofloxacin, gentamicin, linezolid, rifampicin, and tetracycline. Klebsiella pneumoniae and Escherichia coli are highly resistant to ampicillin, but there are drugs with high efficacy for both, including imipenem, piperacillin/tazobactam, aminoglycosides (gentamicin, amikacin), and quinolones (levofloxacin, ciprofloxacin). In contrast to the drug resistance data reported by the China Antimicrobial Resistance Surveillance System (CARSS) in 2017, the detection rate of methicillin-resistant S. aureus (MRSA) and methicillin-resistant coagulase-negative staphylococci (MRCoNS) in the blood cultures of neonates with sepsis exceeded the national average drug resistance level (p < .01). The resistance rate of K. pneumoniae to third-generation cephalosporins was higher than the national average drug resistance level (p < .01), but this organism was most sensitive to carbapenems (carbapenem resistance refers to resistance to any of imipenem, meropenem, or ertapenem). The resistance of Escherichia coli to quinolones was better than the national average level (p < .01).
CONCLUSIONS: Medical care-related infections in neonatal intensive care units (NICUs) were more often caused by CoNS than by S. aureus and Gram-negative bacteria. Vancomycin remains the preferred drug for treating confirmed infections, because most isolated CoNS are resistant to β-lactam drugs including penicillin. For Gram-negative enteric bacteria, aminoglycoside and carbapenem were sufficient for treatment. Compared to the CARSS data on bacterial resistance, the data in this review on the resistance of pathogens causing NS were not favorable. The next goal in antibiotic management in NICUs must be to develop strategies to reduce the use of antibiotics.

Occurrence of microplastics (MPs) in the environment has attracted great attention as it has become a global concern. This review aims to systematically demonstrate the role of marine microplastic as a novel medium for environmental partitioning of chemicals in the ocean, which can cause toxic effects in the ecological environment. This review assimilated and analyzed available data published between 1972 and 2017 on the interaction between MPs and selected chemicals. Firstly, the review analyzes the occurrence of chemicals in MPs and outlines their distribution patterns. Then possible mechanisms of the interaction between MPs and organic chemicals and potential controlling factors were critically studied. Finally, the hazards of MPs and affiliated organic chemicals to marine organisms were shortly summarized.