High enrichment and sensitive measurement of oxytetracycline in tea drinks by thermosensitive magnetic molecular imprinting based magnetic solid phase extraction coupled with boron doped carbon dots.

As a typical kind of new pollutants, there are still some challenges in the rapid detection of antibiotics. In this work, a sensitive fluorescent probe based on boron-doped carbon dots (B-CDs) in combination with thermo-responsive magnetic molecularly imprinted polymers (T-MMIPs) was constructed for the detection of oxytetracycline (OTC) in tea drinks. T-MMIPs were designed, fabricated and employed to enrich OTC at trace level from tea drinks, and B-CDs were utilized as the fluorescent probe to detect the concentration of OTC. The proposed method exhibited good linear relationship with OTC concentration from 0.2 to 60 µg L-1 and the limit of detection was 0.1 µg L-1. The established method has been successfully validated with tea beverages. Present work was the first attempt application of T-MMIPs in combination with CDs in detection of OTC, and demonstrated that the proposed method endowed the detection of OTC with high selectivity, sensitivity, reliability and wide application prospect, meanwhile offered a new strategy for the method establishment of rapid and sensitive detection of trace antibiotics in food and other matrices.

Construction of surface-rich MoS2 nanoflowers decorated on 2D layered MXene nanohybrid heterostructure for highly efficient and rapid degradation of oxytetracycline.

In this study, we successfully developed a hybrid architecture referred to as MoS2@MX, involving the integration of MoS2 layered onto MXene using a straightforward co-precipitation method. This innovative hybrid photocatalyst exhibited remarkable efficiency in removing oxytetracycline (OTC) molecules from aqueous solutions under visible-light irradiation. During the photocatalytic process, both MoS2 and MX played distinct yet complementary roles. MoS2 facilitated efficient electron transfer, while MX contributed to the generation of radicals. This unique collaboration resulted in a noteworthy 99 % oxidation efficiency for OTC degradation within a brief 60 min of visible light exposure in an aqueous environment. The radicals 1O2 and •OH were identified as the principal drivers behind OTC degradation, underscoring the vital role of the hybrid material. Mechanistically, the degradation of OTC involved several key steps, including C-H bond cleavage, de-carboxylation, C-N bond oxidation, and de-chlorination. Importantly, the MoS2@MX hybrid composite demonstrated remarkable stability, maintaining a noteworthy photocatalytic efficiency of 89 % for targeted OTC removal after undergoing five consecutive cycles. In conclusion, this study emphasizes the potential of the MoS2@MX hybrid material as an effective agent for degrading organic OTC compounds within aquatic environments. The hybrid's multifaceted roles and exceptional performance suggest promising applications in sustainable water treatment.

A longitudinal field study of commercial honey bees shows that non-native probiotics do not rescue antibiotic treatment, and are generally not beneficial.

Probiotics are widely used in agriculture including commercial beekeeping, but there is little evidence supporting their effectiveness. Antibiotic treatments can greatly distort the gut microbiome, reducing its protective abilities and facilitating the growth of antibiotic resistant pathogens. Commercial beekeepers regularly apply antibiotics to combat bacterial infections, often followed by an application of non-native probiotics advertised to ease the impact of antibiotic-induced gut dysbiosis. We tested whether probiotics affect the gut microbiome or disease prevalence, or rescue the negative effects of antibiotic induced gut dysbiosis. We found no difference in the gut microbiome or disease markers by probiotic application or antibiotic recovery associated with probiotic treatment. A colony-level application of the antibiotics oxytetracycline and tylosin produced an immediate decrease in gut microbiome size, and over the longer-term, very different and persistent dysbiotic effects on the composition and membership of the hindgut microbiome. Our results demonstrate the lack of probiotic effect or antibiotic rescue, detail the duration and character of dysbiotic states resulting from different antibiotics, and highlight the importance of the gut microbiome for honeybee health.

Estimation of epidemiological cut-off values for eight antibiotics used for treatment of bovine mastitis caused by Streptococcus uberis and Streptococcus dysgalactiae subsp. dysgalactiae.

Interpretive criteria for antimicrobial susceptibility testing are lacking for most antimicrobials used for bovine streptococcal mastitis. The objectives of this study were to determine (tentative) epidemiological cut-off ((T)ECOFF) values for clinically relevant antibiotics used for treatment of bovine mastitis, and to estimate the proportion of acquired resistance (non-wild-types) in Streptococcus dysgalactiae subsp. dysgalactiae and Streptococcus uberis. A total of 255 S. uberis and 231 S. dysgalactiae subsp. dysgalactiae isolates were obtained in Denmark and Norway from bovine mastitis. The isolates were tested for susceptibility to 10 antibiotics using broth microdilution. In accordance with the European Committee on Antimicrobial Susceptibility Testing (EUCAST) standard operating procedure, additional published MIC distributions were included for the estimation of ECOFFs for cloxacillin, cephapirin, lincomycin and tylosin, and TECOFFs for amoxicillin, benzylpenicillin, cephapirin and oxytetracycline. The proportion of non-wild-type (NWT) isolates for the beta-lactams was significantly higher in the Danish S. uberis (45-55%) compared to the Norwegian isolates (10-13%). For oxytetracycline, the proportion of NWT was significantly higher in the Danish isolates, both for S. uberis (28% vs. 3%) and S. dysgalactiae (22% vs. 0%). A bridging study testing in parallel MICs in a subset of isolates (n = 83) with the CLSI-specified and the EUCAST-specified broths showed excellent correlation between the MICs obtained with the two methods. The new ECOFFs and TECOFFs proposed in this study can be used for surveillance of antimicrobial resistance, and - for antimicrobials licensed for streptococcal bovine mastitis - as surrogate clinical breakpoints for predicting their clinical efficacy for this indication.

Nitrogen and phosphorus eutrophication enhance biofilm-related drug resistance in Enterococcus faecalis isolated from Water Sources.

Antibiotic resistance is a critical topic worldwide with important consequences for public health. So considering the rising issue of antibiotic-resistance in bacteria, we explored the impact of nitrogen and phosphorus eutrophication on drug resistance mechanisms in Enterococcus faecalis, especially ciprofloxacin, oxytetracycline, and ampicillin. For this purpose we examined the antibiotic-resistance genes and biofilm formation of Enterococcus faecalis under different concentration of nitrogen and phosphorus along with mentioned antibiotics. Mesocosms were designed to evaluate the impact of influence of eutrophication on the underlying mechanism of drugn resistence in Enterococcus faecalis. For this purpose, we explored the potential relation to biofilm formation, adhesion ability, and the expression levels of the regulatory gene fsrA and the downstream gene gelEI. Our results demonstrated that the isolates of all treatments displayed high biofilm forming potential, and fsrA and gelE genes expression. Additionally, the experimental group demonstrated substantially elevated Enterococcus faecalis gelE expression. Crystal violet staining was applied to observe biofilm formation during bacterial development phase and found higher biofilm formation. In conclusion, our data suggest that E. faecalis resistance to ciprofloxacin, oxytetracycline, and ampicillin is related to biofilm development. Also, the high level of resistance in Enterococcus faecalis is linked to the expression of the fsrA and gelE genes. Understanding these pathways is vital in tackling the rising problem of bacterial resistance and its potential effect on human health.

Silymarin enhances the response to oxytetracycline treatment in Oreochromis niloticus experimentally infected with Aeromonas hydrophila.

Many governments have approved the use of oxytetracycline as an antibiotic additive to food fish, with oxytetracycline now routinely used in many nations. However, oxytetracycline is known to have immunosuppression impacts. We, therefore, evaluated the immunological, antioxidative, and histopathological status of Nile tilapia fed a diet containing silymarin (100 mg/kg fish feed) for 0, 2, 4, 6, and 8 weeks. The protective effects of silymarin against Aeromonas hydrophila (A. hydrophila) infection and oxytetracycline treatment were evaluated. Blood parameters (erythrocyte count, white blood cell count, hemoglobin, and packed cell volume) improved over time in fish fed on dietary silymarin. Serum levels of alanine aminotransferase (ALT) were lower in fish fed on dietary silymarin, whereas serum levels of aspartate transferase (AST)and alkaline phosphatase (ALK) were unchanged. Dietary silymarin affected serum lipid profiles as decreases in serum triglyceride and low-density lipoprotein cholesterol levels and a trend toward lower cholesterol levels, whereas serum high-density lipoprotein cholesterol levels were increased compared to fish fed on the control diet. Dietary silymarin resulted in an increase of serum total protein levels and globulin fractions. Significant and progressive increases in catalase and glutathione peroxidase levels were observed after six weeks of feeding on a dietary silymarin before decreasing to control levels at the end of the experimental period. Fish fed on dietary silymarin, interleukin-1 and fish tumor necrosis factor-alpha were upregulated in hepatic tissues; however, interleukin-10 levels decreased to comparable levels to controls after eight weeks. Fish infected with A. hydrophila displayed septicemia (opaque eye, hemorrhagic ulcers, dentated fins, hepatomegaly, and splenomegaly). Reduced mortality was observed in Nile tilapia infected with A. hydrophila and fed a diet containing silymarin, indicating that silymarin improves fish responses to oxytetracycline with a 37% reduction in mortality.

Unravelling the resilience of magnetite assisted granules to starvation and oxytetracycline stress.

Starvation and antibiotics pollution are two frequent perturbations during breeding wastewater treatment process. Supplying magnetite into anaerobic system has been proved efficient to accelerate microbial aggregates and alleviate the adverse effect caused by process disturbance. Nevertheless, whether these magnetite-based granules are still superior over normal granules after a long-term starvation period remains unknown, the responsiveness of these granules to antibiotics stress is also ambiguous. In current study, we investigated the resilience of magnetite-based anaerobic granular sludge (AnGS) to starvation and oxytetracycline (OTC) stress, by unravelling the variations of reactor performance, sludge properties, ARGs dissemination and microbial community. Compared with the AnGS formed without magnetite, the magnetite assisted AnGS appeared more robust defense to starvation and OTC stress. With magnetite supplement, the average methane yield after starvation recovery, 50 mg/L and 200 mg/L OTC stress was enhanced by 48.95%, 115.87% and 488.41%, respectively, accompanied with less VFAs accumulation, improved tetracycline removal rate (76.3-86.6% vs. 51.0-53.5%) and higher ARGs reduction. Meanwhile, magnetite supplement effectively ameliorated the potential sludge breakage by triggering more large granules formation. Trichococcus was considered an important impetus in maintaining the stability of magnetite-based AnGS process. By inducing more syntrophic methanogenesis partnerships, especially for hydrogenotrophic methanogenesis, magnetite ensured the improved reactor performance and stronger resilience at stress conditions.

Impact of veterinary antibiotics on plasmid-encoded antibiotic resistance transfer.

OBJECTIVES: Resistance genes can be genetically transmitted and exchanged between commensal and pathogenic bacterial species, and in different compartments including the environment, or human and animal guts (One Health concept). The aim of our study was to evaluate whether subdosages of antibiotics administered in veterinary medicine could enhance plasmid transfer and, consequently, resistance gene exchange in gut microbiota. METHODS: Conjugation frequencies were determined with Escherichia coli strains carrying IncL- (blaOXA-48) or IncI1-type (blaCTX-M-1) plasmids subjected to a series of subinhibitory concentrations of antibiotics used in veterinary medicine, namely amoxicillin, ceftiofur, apramycin, neomycin, enrofloxacin, colistin, erythromycin, florfenicol, lincomycin, oxytetracycline, sulfamethazine, tiamulin and the ionophore narasin. Treatments with subinhibitory dosages were performed with and without supplementation with the antioxidant edaravone, known as a mitigator of the inducibility effect of several antibiotics on plasmid conjugation frequency (PCF). Expression of SOS-response associated genes and fluorescence-based reactive oxygen species (ROS) detection assays were performed to evaluate the stress oxidative response. RESULTS: Increased PCFs were observed for both strains when treating with florfenicol and oxytetracycline. Increased expression of the SOS-associated recA gene also occurred concomitantly, as well as increased ROS production. Addition of edaravone to the treatments reduced their PCF and also showed a decreasing effect on SOS and ROS responses for both plasmid scaffolds. CONCLUSIONS: We showed here that some antibiotics used in veterinary medicine may induce transfer of plasmid-encoded resistance and therefore may contribute to the worldwide spread of antibiotic resistance genes.

Network meta-analysis of the therapeutic effects of various antibiotics on footrot in sheep and cattle.

The present network meta-analysis was performed to compare the effects of antibiotics used in treating footrot in some ruminants and to rank these antibiotics based on their efficacy. Data of 14 eligible studies consisting of 5622 affected animals was included in the analysis. A Bayesian method and Markov Chain Monte Carlo (MCMC) simulations were utilized to analyze data. The estimated results were reported in the form of odds ratios (ORs) with 95% credible intervals (CrI). The Surface Under the Cumulative Ranking Curve (SUCRA) was used to rank antibiotics. Network meta-regressions (NMRs) were conducted to examine the influence of sample sizes, treatment duration, route of administration, and species of animals (sheep and cattle) on the overall outcome. The results indicated that gamithromycin impact on curing footrot was superior to other antibiotics and Lincomycin and oxytetracycline were ranked second and third. The difference between the impact of gamithromycin and amoxicillin (OR = 14.76, CrI: 1.07-193.49) and enrofloxacin (OR = 20.21, CrI: 1.57-229.25) on footrot was significant. There was a significant difference between the effect of oxytetracycline and enrofloxacin (OR = 5.24, CrI: 1.14-23.74) on footrot. The NMR performed based on species of animals fitted data better than network meta-analysis, suggesting erythromycin as the best third antibiotic instead of oxytetracycline. Egger's regression test and the shape of the funnel plot showed no publication bias among included studies. In conclusion, gamithromycin was associated with the highest curing rate benefit when used to treat footrot, followed by lincomycin and oxytetracycline/erythromycin. Among all evaluated antibiotics, enrofloxacin showed the lowest effects on footrot.

Oxytetracycline-induced oxidative liver damage by disturbed mitochondrial dynamics and impaired enzyme antioxidants in largemouth bass (Micropterus salmoides).

Oxytetracycline (OTC), a commonly used tetracycline antibiotic in aquaculture, has been found to cause significant damage to the liver of largemouth bass (Micropterus salmoides). This study revealed that OTC can lead to severe histopathological damage, structural changes at the cellular level, and increased levels of reactive oxygen species (ROS) in M. salmoides. Meanwhile, OTC impairs the activities of antioxidant enzyme (such as T-SOD, CAT, GST, GR) by suppressing the activation of MAPK/Nrf2 pathway. OTC disrupts mitochondrial dynamics and mitophagy through via PINK1/Parkin pathway. The accumulation of damaged mitochondria, combined with the inhibition of the antioxidant enzyme system, contributes to elevated ROS levels and oxidative liver damage in M. salmoides. Further investigations demonstrated that an enzyme-treated soy protein (ETSP) dietary supplement can help maintain mitochondrial dynamic balance by inhibiting the PINK1/Parkin pathway and activate the MAPK/Nrf2 pathway to counteract oxidative damage. In summary, these findings highlight that exposure to OTC disrupts mitochondrial dynamics and inhibits the antioxidant enzyme system, ultimately exacerbating oxidative liver damage in M. salmoides. We propose the use of a dietary supplement as a preventive measure against OTC-related side effects, providing valuable insights into the mechanisms of antibiotic toxicity in aquatic environments.

Therapeutic efficacy of enrofloxacin in treatment of Francisella orientalis infections in juvenile Nile tilapia (Oreochromis niloticus L.).

Outbreaks of infections by Francisella orientalis represent one of the main obstacles to Nile tilapia (Oreochromis niloticus L.) farming. It is responsible for acute mortality in fingerlings and juveniles. The main control measure available is oral antibiotic therapy. This study compared the therapeutic efficacy of the antibiotics enrofloxacin and oxytetracycline, the most commonly used antimicrobial, against francisellosis in juvenile Nile tilapia (O. niloticus). Fish were challenged with a virulent isolate of F. orientalis and treated with medicated feed containing one of two doses of oxytetracycline (100 or 300 mg/kg of live weight (LW)) or 10 mg/kg of LW of enrofloxacin. The positive and negative control groups received feed without antibiotics; the negative control group was unchallenged. The results showed that enrofloxacin at a dose of 10 mg/kg of LW is effective against francisellosis in juvenile Nile tilapia (O. niloticus). Treatment with oxytetracycline did not eliminate the pathogen from the infected host, and the surviving fish became carriers. Enrofloxacin was able to cure the fish of infection with F. orientalis. This study suggests that enrofloxacin is a better option for treating francisellosis in Nile tilapia (O. niloticus L.). It controls mortality and avoids the carrier state in the fish, thus reducing the possibility of recurrence in the affected batches.

Study of the effect of administration of narasin or antibiotics on in vivo selection of a narasin- and multidrug-resistant Enterococcus cecorum strain.

Enterococcus cecorum is a member of the normal poultry gut microbiota and an emerging poultry pathogen. Some strains are resistant to key antibiotics and coccidiostats. We evaluated the impact on chicken excretion and persistence of a multidrug-resistant E. cecorum of administering narasin or antibiotics. E. cecorum CIRMBP-1294 (Ec1294) is non-wild-type to many antimicrobials, including narasin, levofloxacin, oxytetracycline and glycopeptides, it has a low susceptibility to amoxicillin, and carries a chromosomal vanA operon. Six groups of 15 chicks each were orally inoculated with Ec1294 and two groups were left untreated. Amoxicillin, oxytetracycline or narasin were administered orally to one group each, either at the recommended dose for five days (amoxicillin, oxytetracycline) or continuously (narasin). Faecal samples were collected weekly and caecal samples were obtained from sacrificed birds on day 28. Ec1294 titres were evaluated by culture on vancomycin- and levofloxacin-supplemented media in 5 % CO2. For inoculated birds given narasin, oxytetracycline or no antimicrobials, vancomycin-resistant enterococci were searched by culture on vancomycin-supplemented media incubated in air, and a PCR was used to detect the vanA gene. Ec1294 persisted in inoculated chicks up to day 28. Compared to the control group, the Ec1294 titre was significantly lower in the amoxicillin- and narasin-receiving groups on days 21 and 28, but was unexpectedly higher in the oxytetracycline-receiving group before and after oxytetracycline administration, preventing a conclusion for this group. No transfer of the vanA gene to other enterococci was detected. Other trials in various experimental conditions should now be conducted to confirm this apparent absence of co-selection of the multi-drug-resistant E. cecorum by narasin or amoxicillin administration.

Foliar Antibiotic Treatment Reduces Candidatus Liberibacter asiaticus Acquisition by the Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Liviidae), but Does not Reduce Tree Infection Rate.

Huanglongbing (HLB), or citrus greening, is the most destructive disease of cultivated citrus worldwide. Candidatus Liberibacter asiaticus (CLas), the putative causal agent of HLB, is transmitted by the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae). In Florida, D. citri was first reported in 1998, and CLas was confirmed in 2005. Management of HLB relies on the use of insecticides to reduce vector populations. In 2016, antibiotics were approved to manage CLas infection in citrus. Diaphorina citri is host to several bacterial endosymbionts and reducing endosymbiont abundance is known to cause a corresponding reduction in host fitness. We hypothesized that applications of oxytetracycline and streptomycin would reduce: CLas populations in young and mature citrus trees, CLas acquisition by D. citri, and D. citri abundance. Our results indicate that treatment of citrus with oxytetracycline and streptomycin reduced acquisition of CLas by D. citri adults and emerging F1 nymphs as compared with that observed in trees treated only with insecticides, but not with antibiotics. However, under field conditions, neither antibiotic treatment frequency tested affected CLas infection of young or mature trees as compared with insecticide treatment alone (negative control); whereas trees enveloped with mesh screening that excluded vectors did prevent bacterial infection (positive control). Populations of D. citri were not consistently affected by antibiotic treatment under field conditions, as compared with an insecticide only comparison. Collectively, our results suggest that while foliar application of oxytetracycline and streptomycin to citrus reduces acquisition of CLas bacteria by the vector, even high frequency applications of these formulations under field conditions do not prevent or reduce tree infection.

Adsorption and transformation of tetracyclines on alpha alumina particles with surface modification by anionic surfactant.

The adsorption and transformation of tetracyclines (TCs) antibiotics, including oxytetracycline (OTC), chlortetracycline (CTC), and tetracycline (TC), on the sodium dodecyl sulfate (SDS) surfactant-modified α-Al2O3 particles were comprehensively investigated in this study. The TCs adsorption was significantly enhanced by using the modified adsorbents compared with the use of the unmodified adsorbents. The experimental conditions were systematically optimized and found to be pH 4, NaCl 1 mM, the contact time of 180 min, and the adsorbent dosage of 25 mg. mL-1. The high maximum adsorption capacities were approximately 320, 85, and 91 mg. g-1 for TC, OTC, and CTC, respectively. Meanwhile, the great removal efficiencies of the three antibiotics TC, OTC, and CTC were correspondingly 91.85, 88.4, and 98.3%. The TCs adsorption isotherm and kinetics on the SDS-modified α-Al2O3 particles mainly governed by the electrostatic and hydrophobic interactions were clarified by a suitable two-step model, the Fourier transform infrared spectroscopy (FT-IR) and zeta potential measurements. Meanwhile, the TCs structural transformation determined by the liquid chromatography with tandem mass spectrometry (LC-MS/MS) measurement was promoted through the adsorption on the α-Al2O3 surface. The TCs transformation rates strongly affected by the TCs adsorption were in the order of CTC > TC > OTC. The found results are promised that the SDS-modified α-Al2O3 particles might behave as high-performance adsorbents to remove the TCs from aqueous solutions.

Ecological Responses of Maize Rhizosphere to Antibiotics Entering the Agricultural System in an Area with High Arsenicals Geological Background.

Metal(loid)s can promote the spread and enrichment of antibiotic resistance in the environmental ecosystem through a co-selection effect. Little is known about the ecological effects of entering antibiotics into the environment with long-term metal(loid)s' resistance profiles. Here, cow manure containing oxytetracycline (OTC) or sulfadiazine (SA) at four concentrations (0 (as control), 1, 10, and 100 mg/kg) was loaded to a maize cropping system in an area with high a arsenicals geological background. Results showed that exogenous antibiotics entering significantly changed the nutrient conditions, such as the concentration of nitrate nitrogen, ammonium nitrogen, and available phosphorus in the maize rhizosphere soil, while total arsenic and metals did not display any differences in antibiotic treatments compared with control. Antibiotics exposure significantly influenced nitrate and nitrite reductase activities to reflect the inhibition of denitrification rates but did not affect the soil urease and acid phosphatase activities. OTC treatment also did not change soil dehydrogenase activities, while SA treatment posed promotion effects, showing a tendency to increase with exposure concentration. Both the tested antibiotics (OTC and SA) decreased the concentration of arsenite and arsenate in rhizosphere soil, but the inhibition effects of the former were higher than that of the latter. Moreover, antibiotic treatment impacted arsenite and arsenate levels in maize root tissue, with positive effects on arsenite and negative effects on arsenate. As a result, both OTC and SA treatments significantly increased bioconcentration factors and showed a tendency to first increase and then decrease with increasing concentration. In addition, the treatments decreased translocation capacity of arsenic from roots to shoots and showed a tendency to increase translocation factors with increasing concentration. Microbial communities with arsenic-resistance profiles may also be resistant to antibiotics entering.

Susceptibility of caprine mastitis pathogens to tildipirosin, gamithromycin, oxytetracycline, and danofloxacin: effect of serum on the in vitro potency of current macrolides.

Mastitis is a significant disease in dairy ruminants, causing economic losses to the livestock industry and severe risks to public health. Antibiotic therapy is one of the most crucial practices to treat mastitis, although the susceptibility of caprine mastitis pathogens to current antibiotics has not been tested under standard or modified incubation conditions. This work evaluated the in vitro activity of tildipirosin, gamithromycin, oxytetracycline, and danofloxacin against caprine mastitis pathogens incubated following standard conditions of Clinical and Laboratory Standards Institute (CLSI) and deviation method by 25% supplementation with goat serum. Mycoplasma agalactiae, Escherichia coli, Staphylococcus aureus, Streptococcus spp., and coagulase-negative Staphylococci (CNS) were isolated from dairy goats with mastitis in Spain. Minimum inhibitory concentrations (MICs) were determined using the broth microdilution technique. The lowest MIC90 under standard conditions was obtained with danofloxacin for mastitis-causing pathogens. An exception was M. agalactiae, where danofloxacin and oxytetracycline obtained low values. However, after adding serum, gamithromycin showed the lowest MIC50 for S. aureus, Streptococcus spp., and CNS. The lowest MIC50 was obtained with all the antibiotics tested (< 0.125 µg/ml) against M. agalactiae. Supplementing with serum resulted in a significant variation in tildipirosin and gamithromycin MIC values for CNS, S. aureus, M. agalagtiae, and E. coli. In brief, the MIC for antibiotics used against mastitis should be determined under conditions closely resembling intramammary infections to obtain representative susceptibility patterns against mastitis pathogens. Caprine mastitis pathogens were broadly susceptible to danofloxacin under standard conditions. The potency of macrolides against caprine mastitis pathogens increases when serum is present in culture media.

The responses of marine anammox bacteria-based microbiome to multi-antibiotic stress in mariculture wastewater treatment.

Saline mariculture wastewater containing multi-antibiotics poses a challenge to anaerobic ammonia oxidation (anammox) process. Herein, the halophilic marine anammox bacteria (MAB)-based microbiome was used for treating mariculture wastewater (35‰ salinity) under multi-antibiotics (enrofloxacin + oxytetracycline + sulfamethoxazole, EOS) stress. And the main focus of this study lies in the response of MAB-based microbiome against multi-antibiotics stress. It is found that MAB-based microbiome shows stable community structure and contributes high nitrogen removal efficiency (>90%) even under high stress of EOS (up to 4 mg·L-1). The relative abundance of main functional genus Candidatus Scalindua, responsible for anammox, had little change while controlling the influent EOS concentration within 4 mg·L-1, whereas, significantly decreased to 2.23% at EOS concentration of as high as 24 mg·L-1. As an alternative, antibiotic resistance bacteria (ARB) species Rheinheimera dominated the microbial community of MAB-based biological reactor under extremely high EOS stress (e.g. 24 mg·L-1 in influent). The response mechanism of MAB-based microbiome consists of extracellular and intracellular defenses with dependence of EOS concentration. For example, while EOS within 4 mg·L-1 in this study, most of the antibiotics were retained by extracellular polymeric substances (EPS) via adsorption; If increasing the EOS concentration to 8 and even 24 mg·L-1, part of antibiotics could intrude into the cells and cause the intracellular accumulation of antibiotic resistance genes (ARGs) (total abundance up to 2.44 × 10-1 copies/16S rRNA) for EOS response. These new understandings will facilitate the practical implementation of MAB-based bioprocess for saline nitrogen- and antibiotics-laden wastewater treatment.

Removal of oxytetracycline and ofloxacin in wastewater by microalgae-bacteria symbiosis for bioenergy production.

The development of microalgae-bacteria symbiosis for treating wastewater is flourishing owing to its high biomass productivity and exceptional ability to purify contaminants. A nature-selected microalgae-bacteria symbiosis, mainly consisting of Dictyosphaerium and Pseudomonas, was used to treat oxytetracycline (OTC), ofloxacin (OFLX), and antibiotic-containing swine wastewater. Increased antibiotic concentration gradually reduced biomass productivity and intricately changed symbiosis composition, while 1 mg/L OTC accelerated the growth of symbiosis. The symbiosis biomass productivity reached 3.4-3.5 g/L (5.7-15.3 % protein, 18.4-39.3 % carbohydrate, and 2.1-3.9 % chlorophyll) when cultured in antibiotic-containing swine wastewater. The symbiosis displayed an excellent capacity to remove 76.3-83.4 % chemical oxygen demand, 53.5-62.4 % total ammonia nitrogen, 97.5-100.0 % total phosphorus, 96.3-100.0 % OTC, and 32.8-60.1 % OFLX in swine wastewater. The microbial community analysis revealed that the existence of OTC/OFLX increased the richness and evenness of microalgae but reduced bacteria species in microalgae-bacteria, and the toxicity of OFLX to bacteria was stronger than that of OTC.

Qualitative immunoassay for the determination of tetracycline antibiotic residues in milk samples followed by a quantitative improved HPLC-DAD method.

Environmental contaminant is one of several problems harming people and wildlife. An example of current emerging contaminants are antibiotics residues that can present in water and food. Although antibiotics are intended to treat or prevent human and animal infections, antibiotics have also been used as animal food supplements for their ability to promote growth and feed efficiency. This overuse of antibacterial has resulted in the accumulation of antibiotics residues in food products which are eventually consumed by human. The continuous unnecessary exposure of human to antibiotics through the direct animals meet or milk, or indirectly through plants or soil can increase the chance of the emergence of multi drug resistance bacteria and consequently adversely affecting human health. New regulations have been imposed regarding antibiotics utilization. Due to the scarce of data regarding antibiotics residue conditions in different types of food intended for human consumption in Saudi Arabia, this study proposed an optimized chromatographic method (HPLC-DAD) followed by an immunoassay approach for specifically detecting tetracyclines antibiotics in animal milk samples. The method was carried out using an RP-C18 column with a mobile phase consisting of 0.01 M KH2PO4: acetonitrile:methanol (70:20:10, v/v/v) adjusted to pH 4. Improvements were observed in the method in terms of resolution and sensitivity. The protein precipitation method used for extraction demonstrated high percent recoveries of 85-101%. The method was validated according to the guidelines of the International Conference for Harmonization (ICH). It is evidently clear from these findings that the presence of tetracycline and oxytetracycline antibiotics residues in milk products from the Saudi market are below the maximum residual limits (MRLs).

Effects of oxytetracycline on aerobic granular sludge process: Granulation, biological nutrient removal and microbial community structure.

Formation of aerobic granular sludge (AGS), process performance and microbial community structure were investigated in lab-scale sequencing batch reactors (SBR) operated without and with oxytetracycline (OTC). Granulation of activated sludge and appearance of AGS was observed in parallel SBRs operated without and with OTC. However, formation of well-settling aerobic granules was relatively faster in the SBR fed with 100 µg/L OTC and observed within 2 weeks of start-up. Ammonium, total nitrogen, and phosphorus removals were quickly established in the AGS cultivated without OTC. In contrast, nitrogen and phosphorus removals were lower in the OTC fed SBR. But, a gradual improvement in nitrogen and phosphorus removals was observed. After 45 days, nitrogen and phosphorous removals were stabilized at 99% and 70%, respectively, due to establishment of OTC-tolerant community. qPCR revealed the impact of OTC on ammonium oxidizing bacteria, polyphosphate accumulating organisms and their enrichment during exposure to OTC. Ammonium and phosphorus were majorly removed via nitritation-denitritation and enhanced biological phosphorus removal (EBPR) pathways, respectively, in the presence of OTC. Brevundimonas (35%), Thaurea (14%) sp. Ca. Competibacter (5.6%), and Ca. Accumulibacter (4.2%) were enriched in OTC-fed AGS. Of the two OTC-tolerant strains isolated, Micrococcus luteus exhibited growth and efficient OTC biotransformation at different OTC concentrations. Moreover, M. luteus was predominantly growing in the form of aggregates. Key traits such as tolerance, biotransformation and high autoaggregation ability allowed a niche for this strain in the granules. This work has important implications in understanding the effect of antibiotics on AGS and designing AGS based treatment for antibiotic-laden wastewaters.