High Concentrations Of Erythromycin Research Articles

Resistance genes and extracellular proteins relieve antibiotic stress on the anammox process

The anaerobic ammonium oxidation (anammox) process is regarded as a promising approach to treat antibiotic-containing wastewater. Therefore, it is urgent to elucidate the effects of various antibiotics on the anammox process. Moreover, the mechanism of extracellular polymeric substance (EPS) as protective barriers to relieve antibiotic stress remain unclear. Therefore, the single and combined effects of erythromycin (ETC) and sulfamethoxazole (SMZ), and interactions between EPS and antibiotics were investigated in this study. Based on a 228-day continuous flow experiment, high concentrations of ETC and SMZ had significant inhibitory effects on the nitrogen removal performance of the anammox process, with the abundances of corresponding antibiotic resistance genes (ARGs) increasing. In addition, the combined inhibitory effect of the two antibiotics on the anammox process was more significant and longer-lasting than that of the single. However, the anammox process was able to quickly recover from deterioration. The tolerance of anammox granules to the stress of low-concentration antibiotics was probably attributed to the increase in ARGs and secretion of EPS. Molecular docking simulation results showed that proteins in EPS could directly bind with SMZ and ETC at the sites of GLU-307, HYS-191, ASP-318 and THR-32, respectively. These findings improved our understanding of various antibiotic effects on the anammox process and the interaction mechanism between antibiotics and proteins in EPS.

Combined Effects of Erythromycin and Nutrients on Microalgae in Seawater

A large number of antibiotics and their metabolites eventually enter the ocean, and their potential threat to marine ecosystems demands attention. In this study, Karenia mikimotoi, Prorocentrum donghaiense, and Skeletonema costatum were selected to investigate the effects of different concentrations of erythromycin and nutrients on microalgae biomass, photosynthetic pigment contents, protein contents, superoxide dismutase (SOD) activity, and malondialdehyde (MDA) content. The possibility of whether erythromycin and nutrient limitation can have combined effects on microalgae was explored, and under different nutritional conditions, the impact of erythromycin on marine ecology was evaluated. The study found that nutrient limitation reduces the tolerance of Karenia mikimotoi, Prorocentrum donghaiense, and Skeletonema costatum to erythromycin. Erythromycin in the experimental range (0-1000 μg·L-1) had no significant effect on the growth of Karenia mikimotoi. However, high concentrations of erythromycin (≥100 μg·L-1)significantly inhibited the growth of Prorocentrum donghaiense and Skeletonema costatum. The sensitivity of Skeletonema costatum was the most pronounced.

Effect of erythromycin exposure on the growth, antioxidant system and photosynthesis of Microcystis flos-aquae

Erythromycin, a macrolide antibiotic, is commonly used in human life. This compound and its derivatives have been detected in various aquatic compartments and may pose a serious threat to aquatic organisms. This study investigated the effects of erythromycin on the growth, antioxidant system and photosynthesis of Microcystis flos-aquae. The results showed that at 0.001–0.1μgL−1, erythromycin could stimulate the growth of M. flos-aquae and increase its photosynthetic activity; however, it did not significantly increase the activities of superoxide dismutase (SOD) and catalase (CAT) or the levels of malondialdehyde (MDA) and reactive oxygen species (ROS). In contrast, the growth of M. flos-aquae was significantly inhibited (p<0.01) at high levels of erythromycin, reaching an inhibition rate of 81.6% at 40μgL−1 erythromycin. At the same time, the activities of SOD and CAT along with MDA content also increased significantly (p<0.01), indicating that the high concentrations of erythromycin caused a severe oxidative stress on algae. However, the balance between oxidants and antioxidant enzymes were disrupted because ROS content simultaneously increased. In addition, the fluorescence parameters of M. flos-aquae decreased significantly with both exposure time and increasing concentration of erythromycin, indicating that photosynthesis was inhibited.

Impact of certain household micropollutants on bacterial behavior. Toxicity tests/study of extracellular polymeric substances in sludge

The impact of eight household micropollutants (erythromycin, ofloxacin, ibuprofen, 4-nonylphenol, triclosan, sucralose, PFOA and PFOS (PFAAs)) on the laboratory bacterial strain Escherichia coli MG1655 and on activated sludge from an urban wastewater treatment plant was studied.Growth-based toxicity tests on E. coli were performed for each micropollutants. The effect of micropollutants on activated sludge (at concentrations usually measured in wastewater up to concentrations disturbing the bacterial growth of E. coli) was examined in batch reactors and by comparison to a control reactor (without micropollutants). The bound extracellular polymeric substances (EPS) secreted by the sludge were measured by size exclusion chromatography and their overexpression was considered as an indicator of bacteria sensitivity to environmental changes. The chemical oxygen demand (COD) and the ammonium concentration were monitored to evaluate the biomass ability to remove the macropollution.Some micropollutants induced an increase of bound EPS in activated sludge flocs at concentrations depending on the micropollutant: erythromycin from 100μg/L, ofloxacin from 10μg/L, triclosan from 0.5μg/L, 4-nonylphenol from 5000μg/L and PFAAs from 0.1μg/L. This suggests that the biomass had to cope with new conditions. Moreover, at high concentrations of erythromycin (10mg/L) and ibuprofen (5mg/L) bacterial populations were no longer able to carry out the removal of macropollution.Ibuprofen induced a decrease of bound EPS at all the studied concentrations, probably reflecting a decrease of general bacterial activity. The biomass was not sensitive to sucralose in terms of EPS production, however at very high concentration (1g/L) it inhibited the COD decrease.Micropollution removal was also assessed. Ibuprofen, erythromycin, ofloxacin, 4-nonylphenol and triclosan were removed from wastewater, mainly by biodegradation. Sucralose and PFOA were not removed from wastewater at all, and PFOS was slightly eliminated by adsorption on sludge.

Transcriptional Response of Enterococcus faecalis V583 to Erythromycin

A transcriptional profile of Enterococcus faecalis V583 (V583) treated with erythromycin is presented. This is the first study describing a complete transcriptional profile of Enterococcus. E. faecalis is a common and nonvirulent bacterium in many natural environments, but also an important cause of nosocomial infections. We have used a genome-wide microarray based on the genome sequence of V583 to study gene expression in cells exposed to erythromycin. V583 is resistant to relatively high concentrations of erythromycin, but growth is retarded by the treatment. The effect of erythromycin treatment on V583 was studied by a time course experiment; samples were extracted at five time points over a period of 90 min. A drastic change in gene transcription was seen with the erythromycin-treated cells compared to the untreated cells. Altogether, 260 genes were down-regulated at one or more time points, while 340 genes were up-regulated. Genes encoding hypothetical proteins and genes encoding transport and binding proteins were the two most dominating groups of differentially expressed genes. The gene encoding ermB (EFA0007) was expressed, but not differentially, which indicated that other genes are important for the survival and growth maintenance of V583 treated with erythromycin. One of these genes is a putative MsrC-like protein, which was up-regulated at all time points studied. Other specific genes that were found to be up-regulated were genes encoding ABC transporters and two-component regulatory systems, and these may be genes that are important for the specific response of V583 to erythromycin.

In vitro activity of orally administered antimicrobial agents against Haemophilus influenzae recovered from children monitored longitudinally in a group day-care center

To determine whether the prevalence of resistance to commonly used oral antimicrobial agents varied over time, we compared the in vitro susceptibilities of 217 strains of Haemophilus influenzae recovered from nasopharyngeal secretions of children in a day-care center studied longitudinally between 1979 and 1987. The overall rate of beta-lactamase production in these strains was 18%, with rates of 57% in type b isolates (n = 21) and 14% in non-type b isolates (n = 196). The percentages of isolates for which MICs were less than or equal to 1.0 micrograms/ml for amoxicillin alone, amoxicillin in combination with clavulanic acid, and cefuroxime alone were 82, 92, and 93%, respectively. The percentage of strains for which cefaclor MICs were less than or equal to 1.0 micrograms/ml was only 0.5%. Isolates for which chloramphenicol MICs were greater than 2.0 micrograms/ml or for which trimethoprim-sulfamethoxazole MICs were greater than 0.5/9.5 micrograms/ml were uncommon: 1 and less than 1%, respectively. High concentrations of erythromycin alone and in combination with sulfisoxazole were required to inhibit the majority of test strains; there was no evidence of erythromycin-sulfisoxazole synergy. In vitro susceptibility to commonly used oral antimicrobial agents remained at a constant level when H. influenzae isolates collected from children in a day-care center during 1979 through 1983 were compared with strains collected during 1984 through 1987.

Transfer of Erythromycin Resistance from Clinically Isolated Lysogenic Strains of Streptococcus pyogenes via Their Endogenous Phage

Endogenous bacteriophage from clinically isolated, erythromycin-resistant strains of Streptococcus pyogenes, upon induction by treatment with mitomycin C, were demonstrated to cause transduction of antibiotic resistance yielding transductants resistant to relatively high concentrations of erythromycin. Transduction of resistance to erythromycin via endogenous phage may play a significant role in the emergence of streptococci with multiple resistance in the clinical environment.

Inducible and constitutive resistance to macrolide antibiotics and lincomycin in clinically isolated strains of Streptococcus pyogenes.

STUDIES ON ERYTHROMYCIN RESISTANCE IN STRAINS OF GROUP A STREPTOCOCCI INDICATED THAT THEY WERE COMPRISED OF TWO TYPES: (i) an inducible, resistant type (IR strains) was seen, which manifested immediate logarithmic growth in media containing high concentrations of the drug only after brief previous exposure (induction period) of the organisms to subinhibitory concentrations of erythromycin, and (ii) a constitutive, resistant type (CR strains) which demonstrated, without prior drug exposure, continued logarithmic growth in media containing high concentrations of erythromycin. Subinhibitory concentrations of either chloramphenicol or puromycin, when added to IR strains prior to induction, interfered with their induction by erythromycin. Exposure of CR strains to chloramphenicol did not visibly affect the subsequent growth curve of these strains in media containing high concentrations of erythromycin. In IR strains, resistance to other macrolide antibiotics (oleandomycin, spiramycin, carbomycin, magnamycin) and to lincomycin also was inducible in nature. There was cross-inducibility between erythromycin, other macrolide antibiotics, and lincomycin. CR strains were constitutively resistant to these antibiotics.