Characterization of antibiotic-resistance genes in antibiotic resistance Escherichia coli isolates from a lake

Antimicrobial Resistance Development Pathways in Surface Waters and Public Health Implications

Human health is threatened by antibiotic-resistant bacteria and their related infections, which cause thousands of human deaths every year worldwide. Surface waters are vulnerable to human activities and natural processes that facilitate the emergence and spread of antibiotic-resistant bacteria in the environment. This study evaluated the pathways and drivers of antimicrobial resistance (AR) in surface waters. We analyzed antibiotic resistance healthcare-associated infection (HAI) data reported to the CDC's National Healthcare Safety Network to determine the number of antimicrobial-resistant pathogens and their isolates detected in healthcare facilities. Ten pathogens and their isolates associated with HAIs tested resistant to the selected antibiotics, indicating the role of healthcare facilities in antimicrobial resistance in the environment. The analyzed data and literature research revealed that healthcare facilities, wastewater, agricultural settings, food, and wildlife populations serve as the major vehicles for AR in surface waters. Antibiotic residues, heavy metals, natural processes, and climate change were identified as the drivers of antimicrobial resistance in the aquatic environment. Food and animal handlers have a higher risk of exposure to resistant pathogens through ingestion and direct contact compared with the general population. The AR threat to public health may grow as pathogens in aquatic systems adjust to antibiotic residues, contaminants, and climate change effects. The unnecessary use of antibiotics increases the risk of AR, and the public should be encouraged to practice antibiotic stewardship to decrease the risk.

The Municipal Sewage Discharge May Impact the Dissemination of Antibiotic-Resistant Escherichia coli in an Urban Coastal Beach

To determine the potential of the recreational marine environment as a dissemination vector of antibiotic-resistant microorganisms, the dissemination of antibiotic-resistant E. coli strains isolated from an urban coastal beach was studied. Sixty-nine and thirteen E. coli strains were isolated from the seawater and sand, respectively, in Fujiazhuang bathing beach, China. The average Antibacterial Resistance Index (ARI) value detected in the seawater is approximately three times that in beach sand. All the isolates from the sand were grouped into one cluster and only the isolates from the municipal sewage outlet were classified into three antibiogram clusters that were observed in the hetero-sites of the E. coli isolates. The E. coli strains with multiple antibiotic resistance (58% of total) were prevalent in the seawater, whereas the isolates from the sand were not detected with multiple antibiotic resistance. A significant association (p < 0.05) between all phenotypic and relative genotypic resistance profiles was observed in the isolates, except in the quinolones resistance genotype. The presence of a class 1 integron was significantly correlated with the resistance of E. coli to sulfonamides, streptomycin, and levofloxacin (p < 0.01). This study revealed that the municipal sewage discharge may impact the dissemination of antibiotic-resistant strains in the urban coastal beach, and that the class 1 integrons play an important role in mediating the resistance of E. coli to sulfonamide antibiotics.

Co-infection of H9N2 Influenza A Virus and Escherichia coli in a BALB/c Mouse Model Aggravates Lung Injury by Synergistic Effects

Pathogens that cause respiratory diseases in poultry are highly diversified, and co-infections with multiple pathogens are prevalent. The H9N2 strain of avian influenza virus (AIV) and Escherichia coli (E. coli) are common poultry pathogens that limit the development of the poultry industry. This study aimed to clarify the interaction between these two pathogens and their pathogenic mechanism using a mouse model. Co-infection with H9N2 AIV and E. coli significantly increased the mortality rate of mice compared to single viral or bacterial infections. It also led to the development of more severe lung lesions compared to single viral or bacterial infections. Co-infection further causes a storm of cytokines, which aggravates the host's disease by dysregulating the JAK/STAT/SOCS and ERK1/2 pathways. Moreover, co-infection mutually benefited the virus and the bacteria by increasing their pathogen loads. Importantly, nitric oxide synthase 2 (NOS2) expression was also significantly enhanced by the co-infection. It played a key role in the rapid proliferation of E. coli in the presence of the co-infecting H9N2 virus. Therefore, our study underscores the role of NOS2 as a determinant for bacteria growth and illustrates its importance as an additional mechanism that enhances influenza virus-bacteria synergy. It further provides a scientific basis for investigating the synergistic infection mechanism between viruses and bacteria.

Molecular characterization of multi-drug resistant Escherichia coli isolates from tropical environments in Southeast Asia

The emergence of antibiotic resistance among multidrug-resistant (MDR) microbes is of growing concern, and threatens public health globally. A total of 129 Escherichia coli isolates were recovered from lowland aqueous environments near hospitals and medical service centers in the vicinity of Kuala Lumpur, Malaysia. Among the eleven antibacterial agents tested, the isolates were highly resistant to trimethoprim-sulfamethoxazole (83.7%) and nalidixic acid (71.3%) and moderately resistant to ampicillin and chloramphenicol (66.7%), tetracycline (65.1%), fosfomycin (57.4%), cefotaxime (57.4%), and ciprofloxacin (57.4%), while low resistance levels were found with aminoglycosides (kanamycin, 22.5%; gentamicin, 21.7%). The presence of relevant resistance determinants was evaluated, and the genotypic resistance determinants were as follows: sulfonamides (sulI, sulII, and sulIII), trimethoprim (dfrA1 and dfrA5), quinolones (qnrS), β-lactams (ampC and blaCTX-M), chloramphenicol (cmlA1 and cat2), tetracycline (tetA and tetM), fosfomycin (fosA and fosA3), and aminoglycosides (aphA1 and aacC2). Our data suggest that multidrug-resistant E. coli strains are ubiquitous in the aquatic systems of tropical countries and indicate that hospital wastewater may contribute to this phenomenon.

Antibiotics and antibiotic resistance genes in global lakes: A review and meta-analysis

Lakes are an important source of freshwater, containing nearly 90% of the liquid surface fresh water worldwide. Long retention times in lakes mean pollutants from discharges slowly circulate around the lakes and may lead to high ecological risk for ecosystem and human health. In recent decades, antibiotics and antibiotic resistance genes (ARGs) have been regarded as emerging pollutants. The occurrence and distribution of antibiotics and ARGs in global freshwater lakes are summarized to show the pollution level of antibiotics and ARGs and to identify some of the potential risks to ecosystem and human health. Fifty-seven antibiotics were reported at least once in the studied lakes. Our meta-analysis shows that sulfamethoxazole, sulfamerazine, sulfameter, tetracycline, oxytetracycline, erythromycin, and roxithromycin were found at high concentrations in both lake water and lake sediment. There is no significant difference in the concentration of sulfonamides in lake water from China and that from other countries worldwide; however, there was a significant difference in quinolones. Erythromycin had the lowest predicted hazardous concentration for 5% of the species (HC₅) and the highest ecological risk in lakes. There was no significant difference in the concentration of sulfonamide resistance genes (sul1 and sul2) in lake water and river water. There is surprisingly limited research on the role of aquatic biota in propagation of ARGs in freshwater lakes. As an environment that is susceptible to cumulative build-up of pollutants, lakes provide an important environment to study the fate of antibiotics and transport of ARGs with a broad range of niches including bacterial community, aquatic plants and animals.

Antibiotics in the aquatic environments: A review of lakes, China

The potential threat of antibiotics to the environment and human health has raised significant concerns in recent years. The consumption and production of antibiotics in China are the highest in the world due to its rapid economic development and huge population, possibly resulting in the high detection frequencies and concentrations of antibiotics in aquatic environments of China. As a water resource, lakes in China play an important role in sustainable economic and social development. Understanding the current state of antibiotics in lakes in China is important. Closed and semi-closed lakes provide an ideal medium for the accumulation of antibiotics and antibiotic resistance genes (ARGs). This review summarizes the current levels of antibiotic exposure in relevant environmental compartments in lakes. The ecological and health risks of antibiotics are also evaluated. This review concludes that 39 antibiotics have been detected in the aquatic environments of lakes in China. The levels of antibiotic contamination in lakes in China is relatively high on the global scale. Antibiotic contamination is higher in sediment than water and aquatic organisms. Quinolone antibiotics (QNs) pose the greatest risks. The contents of antibiotics in aquatic organisms are far lower than their maximum residual limits (MRLs), with the exception of the organisms in Honghu Lake. The lakes experience high levels of ARG contamination. A greater assessment of ARG presence and antibiotic exposure are urgent.

Using phenotype microarrays in the assessment of the antibiotic susceptibility profile of bacteria isolated from wastewater in on-site treatment facilities

The scope of the study was to apply Phenotype Biolog MicroArray (PM) technology to test the antibiotic sensitivity of the bacterial strains isolated from on-site wastewater treatment facilities. In the first step of the study, the percentage values of resistant bacteria from total heterotrophic bacteria growing on solid media supplemented with various antibiotics were determined. In the untreated wastewater, the average shares of kanamycin-, streptomycin-, and tetracycline-resistant bacteria were 53, 56, and 42%, respectively. Meanwhile, the shares of kanamycin-, streptomycin-, and tetracycline-resistant bacteria in the treated wastewater were 39, 33, and 29%, respectively. To evaluate the antibiotic susceptibility of the bacteria present in the wastewater, using the phenotype microarrays (PMs), the most common isolates from the treated wastewater were chosen: Serratia marcescens ss marcescens, Pseudomonas fluorescens, Stenotrophomonas maltophilia, Stenotrophomonas rhizophila, Microbacterium flavescens, Alcaligenes faecalis ss faecalis, Flavobacterium hydatis, Variovorax paradoxus, Acinetobacter johnsonii, and Aeromonas bestiarum. The strains were classified as multi-antibiotic-resistant bacteria. Most of them were resistant to more than 30 antibiotics from various chemical classes. Phenotype microarrays could be successfully used as an additional tool for evaluation of the multi-antibiotic resistance of environmental bacteria and in preliminary determination of the range of inhibition concentration.

Comparison of antibiotic resistant Escherichia coli obtained from drinking water sources in northern Tanzania: a cross-sectional study

Background

Antimicrobial resistance (AMR) is a growing and significant threat to public health on a global scale. Escherichia coli comprises Gram-negative, fecal-borne pathogenic and commensal bacteria that are frequently associated with antibiotic resistance. AMR E. coli can be ingested via food, water and direct contact with fecal contamination.

Methods

We estimated the prevalence of AMR Escherichia coli from select drinking water sources in northern Tanzania. Water samples (n = 155) were collected and plated onto Hi-Crome E. coli and MacConkey agar. Presumptive E. coli were confirmed by using a uidA PCR assay. Antibiotic susceptibility breakpoint assays were used to determine the resistance patterns of each isolate for 10 antibiotics. Isolates were also characterized by select PCR genotyping and macro-restriction digest assays.

Results

E. coli was isolated from 71 % of the water samples, and of the 1819 E. coli tested, 46.9 % were resistant to one or more antibiotics. Resistance to ampicillin, streptomycin, sulfamethoxazole, tetracycline, and trimethoprim was significantly higher (15–30 %) compared to other tested antibiotics (0–6 %; P < 0.05). Of the β-lactam-resistant isolates, bla_TEM-1 was predominant (67 %) followed by bla_CTX-M (17.7 %) and bla_SHV-1 (6.0 %). Among the tetracycline-resistant isolates, tet(A) was predominant (57.4 %) followed by tet(B) (24.0 %). E. coli isolates obtained from these water sources were genetically diverse with few matching macro-restriction digest patterns.

Conclusion

Water supplies in northern Tanzania may be a source of AMR E. coli for people and animals. Further studies are needed to identify the source of these contaminants and devise effective intervention strategies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-016-0870-9) contains supplementary material, which is available to authorized users.

Antibiotic concentration and antibiotic-resistant bacteria in two shallow urban lakes after stormwater event

Stormwater runoff is generally characterized as non-point source pollution. In the present study, antibiotic concentration and antibiotic susceptibilities of cultivable heterotrophic bacteria were investigated in two small shallow urban lakes before and after strong storm event. Several antibiotics, lactose-fermenting bacteria and cultivable heterotrophic bacteria concentrations increased in surface water and/or surface sediment of two small urban lakes (Lake Xuanwu and Wulongtan) after strong storm event. In general, the frequencies of bacteria showing resistance to nine antibiotics increased after storm event. Based on the 16S rRNA genes of 50 randomly selected isolates from each water sample of two lakes, Aeromonas and Bacillus were dominant genera in samples from two lakes, while genera Proteus and Lysinibacillus were the third abundant genera in Lake Xuanwu and Wulongtu, respectively. Presences of nine antibiotic resistance genes (ARGs) in the 100 isolates were detected and most of these isolates harbored at least two ARGs with different functions. The detection frequency of ARGs in Gram-negative isolates was higher than that in Gram-positive isolates. The most prevalent integron in 100 isolates was int(II) (n = 28), followed by int(I) (n = 17) and int(III) (n = 17). Our results indicate that strong storm events potentially contribute to the transfer of ARGs and antibiotic-resistant bacteria from land-sewer system to the urban Lakes.

Fate of antibiotic resistant cultivable heterotrophic bacteria and antibiotic resistance genes in wastewater treatment processes

Antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are emerging contaminants of environmental concern. Heterotrophic bacteria in activated sludge have an important role in wastewater treatment plants (WWTPs). However, the fate of cultivable heterotrophic ARB and ARGs in WWPTs process remains unclear. In the present study, we investigated the antibiotic-resistant phenotypes of cultivable heterotrophic bacteria from influent and effluent water of three WWTPs and analysed thirteen ARGs in ARB and in activated sludge from anoxic, anaerobic and aerobic compartments. From each influent or effluent sample of the three plants, 200 isolates were randomly tested for susceptibility to 12 antibiotics. In these samples, between 5% and 64% isolates showed resistance to >9 antibiotics and the proportion of >9-drug-resistant bacteria was lower in isolates from effluent than from influent. Eighteen genera were identified in 188 isolates from influent (n=94) and effluent (n=94) of one WWTP. Six genera (Aeromonas, Bacillus, Lysinibacillus, Microbacterium, Providencia, and Staphylococcus) were detected in both influent and effluent samples. Gram-negative and -positive isolates dominated in influent and effluent, respectively. The 13 tetracycline-, sulphonamide-, streptomycin- and β-lactam-resistance genes were detected at a higher frequency in ARB from influent than from effluent, except for sulA and CTX-M, while in general, the abundances of ARGs in activated sludge from two of the three plants were higher in aerobic compartments than in anoxic ones, indicating abundant ARGs exit in the excess sledges and/or in uncultivable bacteria. These findings may be useful for elucidating the effect of WWTP on ARB and ARGs.

Prevalence of antibiotic resistance genes in antibiotic-resistant Escherichia coli isolates in surface water of Taihu Lake Basin, China

The rapid development of antibiotic-resistant bacteria (ARB) has been of concern worldwide. In this study, antibiotic resistance genes (ARGs) were investigated in antibiotic-resistant Escherichia coli isolated from surface water samples (rivers, n = 17; Taihu Lake, n = 16) and from human, chicken, swine, and Egretta garzetta sources in the Taihu Basin. E. coli showing resistance to at least five drugs occurred in 31, 67, 58, 27, and 18% of the isolates from surface water (n = 665), chicken (n = 27), swine (n = 29), human (n = 45), and E. garzetta (n = 15) sources, respectively. The mean multi-antibiotic resistance (MAR) index of surface water samples (0.44) was lower than that of chicken (0.64) and swine (0.57) sources but higher than that of human (0.30) and E. garzetta sources (0.15). Ten tetracycline, four sulfonamide, four quinolone, five β-lactamase, and two streptomycin resistance genes were detected in the corresponding antibiotic-resistant isolates. Most antibiotic-resistant E. coli harbored at least two similar functional ARGs. Int-I was detected in at least 57% of MAR E. coli isolates. The results of multiple correspondence analysis and Spearman correlation analysis suggest that antibiotic-resistant E. coli in water samples were mainly originated from swine, chicken, and/or human sources. Most of the ARGs detected in E. garzetta sources were prevalent in other sources. These data indicated that human activities may have contributed to the spread of ARB in the aquatic environment.

An integrated quantitative and targeted proteomics reveals fitness mechanisms of Aeromonas hydrophila under oxytetracycline stress

To date, above ten thousand tons of antibiotics are used in aquaculture each year that lead to the deterioration of natural resources. However, knowledge is limited on the molecular biological behavior of common aquatic pathogens against antibiotics stress. In this study, proteomics profiles of Aeromonas hydrophila, which were exposed to different levels of oxytetracycline (OXY) stress, were displayed and compared using iTRAQ labeling and SWATH-MS based LC-MS/MS methods. A total 1383 proteins were identified by SWATH-MS method, and 2779 proteins were identified from iTRAQ labeling samples. There are 152 up-regulated and 52 down-regulated proteins overlapped in 5 μg/mL OXY stress and both 83 up- and down-regulated proteins overlapped in 10 μg/mL OXY stress in both methods, respectively. Results show that many protein synthesis and translation related proteins increased, while energy generation related proteins decreased in OXY stress. The varieties of selected proteins involved in both pathways were further validated by sMRM(HR), q-PCR, and enzyme activity assay. Furthermore, the concentrations of NAD+ and NADH were measured to verify the characteristic of energy generation process in OXY stress and OXY resistance strain. We demonstrate that the down-regulation of energy generation related metabolic pathways and up-regulation of translation may play an important role in antibiotics fitness or resistance of aquatic pathogens.

Quality of water and antibiotic resistance of Escherichia coli from water sources of hilly tribal villages with and without integrated watershed management-a one year prospective study

In many hilly tribal areas of the world, water scarcity is a major problem and diarrhoea is common. Poor quality of water also affects the environment. An integrated watershed management programme (IWMP) aims to increase availability of water and to improve life conditions. Globally, there is a lack of information on water contamination, occurrence of diarrhoea and antibiotic resistance, a serious global concern, in relation to IWMP in hilly tribal areas. Therefore, a prospective observational study was conducted during 2011–2012 in six villages in a hilly tribal belt of India, three with and three without implementation of an IWMP, to explore quality of water, diarrhoeal cases in the community and antibiotic resistance of Escherichia coli from water sources. The results showed that physico-chemical quality of water was within limits of safe consumption in all samples. The odds of coliform contamination in water samples was 2.3 times higher in non-watershed management villages (NWMV) compared to integrated watershed management villages (IWMV) (95% CI 0.8–6.45, p = 0.081). The number of diarrhoeal cases (18/663 vs. 42/639, p < 0.05) was lower in IWMV as compared to NWMV. Overall E. coli isolates showed high susceptibility to antibiotics. Resistance to a wider range of antibiotics was observed in NWMV.

Characterization of Antibiotics and Antibiotic Resistance Genes on an Ecological Farm System

There is a growing concern worldwide about the prevalence of antibiotics and antibiotic resistance genes (ARGs) on the farm. In this study, we investigated the distribution of seven antibiotics and ten ARGs in fresh and dried pig feces, in biogas slurry, and in grape-planting soil from an ecological farm. Antibiotics including sulfamethazine, norfloxacin, ofloxacin, tetracycline, oxytetracycline, and chlortetracycline were detected in these samples (except for sulfamethoxazole) in dried feces. In general, antibiotics levels in samples were in the sequence: biogas slurry > fresh feces > soil or dried feces. Results of ecological risk assessments revealed that among the seven antibiotics chlortetracycline showed the highest ecological risk. Among the ten ARGs,sulI andtetO were the most prevalent on this ecological farm. There were positive correlations between certain ARGs and the corresponding antibiotics on this ecological farm. Therefore, continuous monitoring of antibiotics and their corresponding ARGs should be conducted in the agroecosystem near the concentrated animal farming operation systems.

Predictability of the time-dependent toxicities of aminoglycoside antibiotic mixtures to Vibrio qinghaiensis sp.-Q67

The combined toxicities of all binary mixtures constructed by four aminoglycoside (AG) antibiotics are concentration additive, which has nothing to do with exposure time, mixture ratio, and concentration level.