Sulphonamide Antibiotics Research Articles

Full-Spectrum Utilization of ZIF-67/Ag NPs/NaYF4:Yb,Er Photocatalysts for Efficient Degradation of Sulfadiazine: Upconversion Mechanism and DFT Calculation.

In this work, novel ternary composite ZIF-67/Ag NPs/NaYF4:Yb,Er is synthesized by solvothermal method. The photocatalytic activity of the composite is evaluated by sulfadiazine (SDZ) degradation under simulated sunlight. High elimination efficiency of the composite is 95.4% in 180min with good reusability and stability. The active species (h+, ·O2 - and ·OH) are identified. The attack sites and degradation process of SDZ are deeply investigated based on theoretical calculation and liquid chromatography-mass spectrometry analysis. The upconversion mechanism study shows that favorable photocatalytic effectiveness is attributed to the full utilization of sunlight through the energy transfer upconversion process and fluorescence resonance energy transfer. Additionally, the composite is endowed with outstanding light-absorbing qualities and effective photogenerated electron-hole pair separation thanks to the localized surface plasmon resonance effect of Ag nanoparticles. This work can motivate further design of novel photocatalysts with upconversion luminescence performance, which are applied to the removal of sulphonamide antibiotics in the environment.

Use of Diuretics and Risk of Acute Angle Closure: A Case-Control Study

ABSTRACT Purpose To examine the possible link between acute angle closure (AAC) with use of diuretics. Methods A nested case-control study (NCC) was conducted among a cohort of diuretic users using the PharMetrics Plus database from 2006 to 2020. Cases were identified as the first international classification of diseases 9th and 10th editions (ICD-9/10) code for ACC. For each case, 4 controls were selected and matched to the cases by age and sex using density-based sampling. A conditional logistic regression model was used to compute rate ratios (RRs) adjusted for the drugs topiramate, bupropion, sulphonamide antibiotics, acetazolamide, and sulfasalazine. The RRs for a negative control drug, amlodipine, was also assessed. Results From the initial cohort of 713 574 diuretics users, 1 553 cases and 6 212 controls were identified. No increase in the risk of AAC with current users of diuretics was found (RR = 1.06, (95% CI: 0.81–1.37) for all diuretics; RR = 0.97, (95% CI: 0.71–1.32) for thiazides; RR = 1.24, (95% CI: 0.90–1.73) for loop diuretics; RR = 0.99, (95% CI: 0.73–1.36) for potassium sparing). Conclusion We found no increase in the risk of acute angle closure with use of diuretics. Future studies are needed to confirm these findings.

Effect of subtherapeutic and therapeutic sulfamethazine concentrations on transcribed genes and translated proteins involved in Microbacterium sp. C448 resistance and degradation.

Microbacterium sp. C448, isolated from a soil regularly exposed to sulfamethazine (SMZ), can use various sulphonamide antibiotics as the sole carbon source for growth. The basis for the regulation of genes encoding the sulphonamide metabolism pathway, the dihydropteroate synthase sulphonamide target (folP), and the sulphonamide resistance (sul1) genes is unknown in this organism. In the present study, the response of the transcriptome and proteome of Microbacterium sp. C448 following exposure to subtherapeutic (33 µM) or therapeutic (832 µM) SMZ concentrations was evaluated. Therapeutic concentration induced the highest sad expression and Sad production, consistent with the activity of SMZ degradation observed in cellulo. Following complete SMZ degradation, Sad production tended to return to the basal level observed prior to SMZ exposure. Transcriptomic and proteomic kinetics were concomitant for the resistance genes and proteins. The abundance of Sul1 protein, 100-fold more abundant than FolP protein, did not change in response to SMZ exposure. Moreover, non-targeted analyses highlighted the increase of a deaminase RidA and a putative sulphate exporter expression and production. These two novel factors involved in the 4-aminophenol metabolite degradation and the export of sulphate residues formed during SMZ degradation, respectively, provided new insights into the Microbacterium sp. C448 SMZ detoxification process.

Diffusion of sulphonamide antibiotics in agarose hydrogels enriched by humic acids

Many different pharmaceuticals can evince potentially dangerous behaviour in soil and aqueous environments. Their migration ability and toxicity can be significantly affected by interactions with organic matter. Sulfamethoxazole and sulphapyridine (used as representative commonly used sulphonamide antibiotics) are studied from the point of view of their transport in model hydrogels containing humic substances. Agarose hydrogel was used as a model medium for the transport experiments. Standard Elliot soil humic acid (4S102H) purchased from International Humic Substances Society was incorporated into the hydrogel as an active substance (and representant of organic matter) for interactions with antibiotics and potential suppression of their migration and toxicity in soil systems. Two different experimental arrangements were used: the diffusion from constant source, and the diffusion couple. Diffusion coefficients were determined for pure agarose hydrogels as well as for hydrogels containing humic acids and compared. It was found that the addition of humic acids into hydrogel resulted in the decrease in the effective diffusion coefficient of sulphapyridine and the increase in the effective diffusion coefficient of sulfamethoxazole. Humic acids can suppress the mobility of sulphapyridine and enhance the diffusion of sulfamethoxazole. Batch sorption experiments provided similar adsorption capacities of humic acids for both studied antibiotics. The ratio between adsorption and desorption rate constants were higher than 1 for sulphapyridine and lower than 1 for sulfamethoxazole. It indicated that adsorption predominated for sulphapyridine which resulted in observed lower diffusivity. Desorption experiments showed that a majority of sulphapyridine can be immobilized by interaction with humic acids whereas much more free movable sulfamethoxazole was determined in the comparison with immobilized one.

OZ101, an oligofructose prebiotic, may prolong sulphonylurea efficcy in patients with type 2 diabetes: a pilot study: OZ101 and sulphonylurea-mediated glycaemic control

Aims: The sulphonylurea class of anti-diabetes drugs lose efficacy over time due to progressive beta-cell failure. Their long-term use may exacerbate gut microbial dysbiosis as they are derivatives of sulphonamide antibiotics. We conducted a pilot study to test the hypothesis that OZ101, administered as adjunctive prebiotic therapy, improves beta-cell function and glycaemic control in sulphonylurea-treated patients. Materials and Methods: Subjects with type 2 diabetes on sulphonylurea monotherapy (n=30) were randomized in a 24-week parallel dose range-finding study to either continue receiving their usual sulphonylurea-only treatment or add a thrice-daily regimen of 13.5 or 27 g/d doses of OZ101. HOMA-B, glycaemic parameters after 12 hours fasting, and glucose area under the curve (AUC; over 240 minutes) after intake of a pre-defined calorie milkshake were collected at baseline and 24 weeks. Results: Over 24-weeks, control subjects on sulphonylurea-only showed a decline in beta-cell function (35.54% decrease in HOMA-B from baseline, p = 0.01), whereas subjects taking sulphonylurea+13.5 g/d OZ101 improved (22.9% increase in HOMA-B from baseline, p = 0.031). There was a 0.95% (10mmol/mol) difference in HbA1c (p = 0.047) and 607 mmol/l*240min AUC (p = 0.039) in favour of the sulphonylurea +13.5g/d OZ101 compared with control group. HbA1c and AUC were not altered in subjects treated with sulphonylurea+27 g/d OZ101 compared with the control group. Microbiome profiling suggested reciprocal relationships in beneficial versus detrimental bacteria between control and treatment groups. Conclusions: Adjunctive intake of 13.5g/d OZ101 in patients on sulphonylurea therapy was safe, well-tolerated and associated with improved beta-cell function and stabilization of glycaemic control over 24 weeks. Absence of similar response for the 27 g/d OZ101 group may relate to changes in gut microbiome profiles. Future studies will determine the mechanistic link between OZ101 therapy, changes in gut microbiome, and metabolic responses.

Photoelectrocatalytic degradation of sulphonamide antibiotics in aquatic media using a novel Co-doped ZnO nanocomposite: evaluation of performance, kinetic studies

ABSTRACT It is well known that antibiotics’ residues in aquatic environments are a great threat to human health and ecology. Thus, it is vital to develop efficient strategies to overcome the mentioned threat and degrade the pointed out residues as much as possible. Herein, a novel Co-doped ZnO nanocomposite was fabricated and deposited on fluorine-doped tin oxide glass sheets (FTO) and eventually applied for the photoelectrocatalytic degradation of four sulphonamides (SAs), namely sulphacetamide (SCT), sulphathiazole (STZ), sulfamethoxazole (SMX) and sulphadiazine (SDZ) under visible light irradiation. In this regard, the effect of initial pH (3–11), applied current (0.5–1.5 mA/cm2), initial concentration of SAs (5–20 mg/L) were thoroughly investigated. The results indicated that under the optimal conditions (pH = 9, [SAs] = 5 mg/L and applied current = 1.5 mA/cm2), the degradation efficiencies obtained under a 90-min of reaction time were as follows: SCT (97.1%), SMX (95.8%), SDZ (93.2%) and STZ (91.8%). In addition, the degradation of the SAs by the applied photoelectrocatalytic process (PECP) followed the first-order kinetic model. Meanwhile, the applied PECP exhibited an excellent performance with regard to real samples. Finally, PECP is reckoned to be associated with ‘green’ technologies as electricity is involved and the used catalyst will not end up in the environment as secondary toxic materials.

Genomic Analysis of Delftia tsuruhatensis Strain TR1180 Isolated From A Patient From China With In4-Like Integron-Associated Antimicrobial Resistance.

Delftia tsuruhatensis has become an emerging pathogen in humans. There is scant information on the genomic characteristics of this microorganism. In this study, we determined the complete genome sequence of a clinical D. tsuruhatensis strain, TR1180, isolated from a sputum specimen of a female patient in China in 2019. Phylogenetic and average nucleotide identity analysis demonstrated that TR1180 is a member of D. tsuruhatensis. TR1180 exhibited resistance to β-lactam, aminoglycoside, tetracycline and sulphonamide antibiotics, but was susceptible to phenicols, fluoroquinolones and macrolides. Its genome is a single, circular chromosome measuring 6,711,018 bp in size. Whole-genome analysis identified 17 antibiotic resistance-related genes, which match the antimicrobial susceptibility profile of this strain, as well as 24 potential virulence factors and a number of metal resistance genes. Our data showed that Delftia possessed an open pan-genome and the genes in the core genome contributed to the pathogenicity and resistance of Delftia strains. Comparative genomics analysis of TR1180 with other publicly available genomes of Delftia showed diverse genomic features among these strains. D. tsuruhatensis TR1180 harbored a unique 38-kb genomic island flanked by a pair of 29-bp direct repeats with the insertion of a novel In4-like integron containing most of the specific antibiotic resistance genes within the genome. This study reports the findings of a fully sequenced genome from clinical D. tsuruhatensis, which provide researchers and clinicians with valuable insights into this uncommon species.

Hydrochlorothiazide and Indapamide bind the NADPH binding site of bacterial Dihydrofolate Reductase: results of an in-silico study and their implications.

Hypertension is a public health concern. Low dose thiazide diuretics are known to effectively control blood pressure compared to that of other classes of antihypertensive drugs. In this context, we have performed an in-silico study and found that the two Sulphonamide Diuretics Hydrochlorothiazide and Indapamide bound the NADPH binding region of bacterial Dihydrofolate Reductase. Therefore, akin to Sulphonamide Antibiotics, Sulphonamide Diuretics may have antibiotic activity and thereby have the potential to modulate the gut microbiome in a way beneficial to vascular health. The in-silico experiment results were analyzed in the context of the relevant literature. We postulate that Sulphonamide Diuretics exert their antihypertensive role by modulating the gut microbiome, specifically by increasing butyrate-producing taxa in the gut. We recommend extending such work as it is plausible that Indapamide and other Sulphonamide Diuretics may be beneficial for both diabetes and hypertension.

Study of free nitrous acid (FNA)-based elimination of sulfamethoxazole: Kinetics, transformation pathways, and toxicity assessment

Free nitrous acid (FNA)-based applications have been broadly adopted in the development of novel wastewater management technologies, but a basic understanding of the effect of the chemical properties of FNA on the elimination of micropollutants is still lacking. This study aims to comprehensively evaluate FNA-based elimination of sulfamethoxazole (SMX), which is a typical species of sulphonamide antibiotics. Batch experiments were conducted under different influencing factors to investigate the antibiotics elimination processes. We found that FNA showed specific efficacy on sulphonamides characterized by sulfonamide and aniline functional groups, such as SMX. SMX degradation was affected by the initial SMX concentration, FNA concentration and solution pH and described by d[SMX]/dt=−0.29e−1.69pH[SMX]0.945[FNA]1.35. The cationic forms of SMX were more reactive towards FNA-based active components. Sulfonamide bond (S-N or C-S bonds) cleavage, nitrosubstitution, deamination and radical oxidation were proposed to be the relevant transformation pathways. The FNA-based technique was not effective for diminishing toxicity, but this process could strongly control antibacterial activity.

Transcriptomic analysis reveals root metabolic alteration and induction of huanglongbing resistance by sulphonamide antibiotics in huanglongbing‐affected citrus plants

AbstractHuanglongbing (HLB) is a devastating disease that affects the entire citrus plant, including the root system. Previous studies have shown that sulphonamide antibiotics can suppress titres of the pathogen that causes HLB, ‘Candidatus Liberibacter asiaticus’ (CLas), and affect root morphology in the plant through unknown mechanisms. To better understand the response of CLas‐infected roots to sulphonamide antibiotics, hydroponic cultures of CLas‐infected citrus roots were treated with sulfadimethoxine sodium (SDX), indole butyric acid (IBA), or water for 60 days to evaluate root metabolism and resistance against CLas via transcriptomic analysis. This study indicated that SDX and IBA treatments increased active root surface area in HLB‐affected citrus, which may be due to root hair and lateral root growth. CLas titres in HLB‐affected citrus roots treated with SDX were lower than those of IBA and control treatments. Function categorization indicated that plant hormone signal transduction and plant–pathogen interaction were the most markedly enriched pathways in the HLB‐affected citrus root after SDX treatment. The expression of genes involved in biosynthesis of auxin and ethylene, which are related to root hair and lateral root growth, were up‐regulated by SDX. Moreover, SDX also induced genes related to the metabolism of jasmonates, brassinosteroids, reactive oxygen species, and secondary metabolites, which are beneficial for resistance against HLB. In conclusion, we propose a model for SDX in regulating metabolic pathways in the root and resistance against CLas in HLB‐affected citrus root, which is beneficial for recovering an HLB‐affected citrus root system and combating CLas.

Anaphylactic shock with intravenous furosemide: a rare undesired effect

Furosemide is a potent diuretic, with structural similarity to sulphonamide antibiotics. Its relative safety profile is one of the reasons to account for its widespread use. We report a rare case of fatal anaphylaxis with intravenous furosemide administered in our critical care settings for pulmonary edema. Chemical similarity of furosemide with sulphonamide antibiotics shares the possibility of similar allergic side effects. Thus, a more careful clinical use of furosemide, especially if administered intravenous should be kept in mind to avoid such catastrophic events.

Variability of the Ability of Complex Microbial Communities to Exclude Microbes Carrying Antibiotic Resistance Genes in Rabbits.

Reducing antibiotic use is a necessary step toward less antibiotic resistance in livestock, but many antibiotic resistance genes can persist for years, even in an antibiotic-free environment. In this study, we investigated the potential of three fecal complex microbial communities from antibiotic-naive does to drive the microbiota of kits from antibiotic-exposed dams and outcompete bacteria-carrying antibiotic-resistant genes. The fecal complex microbial communities were either orally delivered or simply added as fresh fecal pellets in four to five nests that were kept clean from maternal feces. Additionally, four nests were cleaned for the maternal feces and five nests were handled according to the common farm practice (i.e., cleaning once a week) as controls. At weaning, we measured the relative abundance of 26 antibiotic resistance genes, the proportion of Enterobacteriaceae resistant to tetracycline and sulfonamide antibiotics, and the taxonomic composition of the microbiota by sequencing the 16S rRNA genes of one kit per nest. Changing the surrounding microbes of the kits can hinder the transmission of antibiotic resistance genes from one generation to the next, but the three communities widely differed in their ability to orient gut microbes and in their impact on antibiotic resistance genes. The most efficient delivery of the microbial community reduced the proportion of resistant Enterobacteria from 93 to 9%, decreased the relative abundance of eight antibiotic resistance genes, and changed the gut microbes of the kits at weaning. The least efficient did not reduce any ARG or modify the bacterial community. In addition, adding fecal pellets was more efficient than the oral inoculation of the anaerobic suspension derived from these fecal pellets. However, we were unable to predict the outcome of the exclusion from the data of the donor does (species composition and abundance of antibiotic resistance genes). In conclusion, we revealed major differences between microbial communities regarding their ability to exclude antibiotic resistance genes, but more work is needed to understand the components leading to the successful exclusion of antibiotic resistance genes from the gut. As a consequence, studies about the impact of competitive exclusion should use several microbial communities in order to draw general conclusions.

Antibiotic Drug Use and the Risk of Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis: A Population-Based Case-Control Study

Abstract Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are rare, life-threatening mucocutaneous adverse drug reactions. Sulphonamide antibiotics are commonly accepted as one of the primary causes of SJS/TEN. This notion is based on results from two hospital-based case-control studies that identified the combined antibiotic cotrimoxazole (sulfamethoxazole and trimethoprim) as the cause of several SJS/TEN cases. Associations were also reported for penicillins, quinolones, cephalosporins, macrolides, tetracyclines, and metronidazole. Using data from the UK-based Clinical Practice Research Datalink, we conducted a 1:4-matched case-control study including 480 previously validated SJS/TEN cases (1995-2013) to quantify the association between SJS/TEN and antibiotics. We further quantified absolute risks of SJS/TEN within separate cohorts of antibiotic users and assessed causality in each exposed case using an adapted version of the algorithm of drug causality in epidermal necrolysis (ALDEN). We observed a strong association between SJS/TEN and trimethoprim alone (odds ratio=9.44, 95% CI 3.83-23.25; absolute risk: 0.98 cases/100’000 users), which suggests that the previously reported association between cotrimoxazole and SJS/TEN is at least partly attributable to the non-sulphonamide antibiotic trimethoprim, which is frequently prescribed as a single agent in the UK. Our study further corroborates previously reported associations between SJS/TEN and use of penicillins, quinolones, cephalosporins, and macrolides.

Nimesulide induced Stevens Johnson Syndrome: a case report

Adverse drug reactions to the prescribed medicines are the major obstacles in continuation of drug treatment. Stevens- Johnson Syndrome (SJS) is a severe, episodic, acute mucocutaneous reaction which is most commonly elicited by drugs and occasionally by infections. Common drugs associated with SJS are sulphonamide antibiotics, anticonvulsants, non- steroidal anti-inflammatory drugs (NSAIDS) and allopurinol. Nimesulide is an NSAID with analgesic and antipyretic properties. Here, we report a case of 21 years old male patient who developed Stevens Johnson Syndrome following ingestion of tablet Nimesulide. The patient was managed with parenteral corticosteroids, antibiotics, emollients, and supportive care. This case highlights the importance of Nimesulide and other NSAIDs as possible cause of SJS. Nimesulide has never been approved in countries like USA, Canada, Australia. But in India it is available as over the counter drug and is used for various indications like fever, myalgia, arthralgia. Therefore, the drugs which are banned outside India should be used with caution and practitioners should report all the adverse drug reactions to such drugs.

Evolution, evidence and effect of secondary prophylaxis against rheumatic fever

The association between group A streptococcal infection and rheumatic fever (RF) was established in the early 20 th century. At the time, RF and subsequent rheumatic heart disease (RHD) were an untreatable scourge of young people in developed and developing countries. Resultingly, research efforts to understand, treat and prevent the disease were widepread. The development of antibiotics in the 1930s offered therapeutic promise, although antibotic treatment of acute RF had little impact. Improved understanding of the post-infectious nature of RF prompted attempts to use antibiotics prophylactically. Regular doses of sulphonamide antibiotics following RF appeared to reduce disease progression to RHD. Development of penicillin and later, benzathine penicillin G, was a further thereputic advance in the 1950s. No new prophylactic options against RF have emerged in the intervening 60 years, and delivery of regularly scheduled BPG injections remains a world wide challenge.

Screening and determination of sulphonamide residues in bovine milk samples using a flow injection system

A new, simple, rapid and sensitive flow injection spectrophotometric method was developed for the screening and determination of sulphonamides in bovine milk samples. The method is based on the condensation of sulphathiazole, sulphamethazine, and sulphadimethoxine with p-dimethylaminobenzaldehyde (p-DAB) in acid medium, in the presence of sodium dodecyl sulphate (SDS), producing a yellow compound (λmax=465nm). Optimisation of the experimental parameters was performed using a multivariate methodology. The linear range was 90–500μg/L and the limits of detection and quantification were in the ranges 25–29μg/L and 84–88μg/L, respectively. The procedure was applied for the determination of sulphonamide antibiotics in bovine milk samples submitted to a prior extraction procedure based on QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) methodology. Recoveries of 60.5–70.5% were achieved for milk samples spiked with 0.09, 0.1, 0.2, and 0.3μg/g of each sulphonamide.

SYNTHESIS AND IN VITRO ANTIBACTERIAL ACTIVITY OF FOUR NOVEL PLEUROMUTILIN DERIVATIVES

ABSTRACT Four novel pleuromutilin derivatives with butyl amine group in the C-14 side-chain were designed, synthesized and confirmed by FT-IR, 1 H-NMR and HR-MS. The results of antibacterial activity showed that the antibacterial activity of pleuromutilin derivatives could be affected by the steric hindrance of their C-14 side-chain. Key words: pleuromutilin derivatives, antibacterial, Staphylococcus aureus . INTRODUCTION Due to the dramatic increasing of antibiotic resistance among pathogenic bacterial strains, research efforts are focusing on new antibiotics that have unique modes of action and activity against resistant organisms. During the past 25 years, the number of antibiotics which have been approved by the Food and Drug Administration (FDA) decreased annually. 1 Actually, after the discovery of sulphonamide antibiotics in the 1930s and penicillin in the 1940s, there were only three novel classes of antibacterials, the topical antibiotic mupirocin, the oxazolidinones (linezolid) and the cyclic lipopeptides (daptomycin) which had entered the market.

Highly sensitive and simultaneous determination of sixteen sulphonamide antibiotics, four acetyled metabolites and trimethoprim in meat by rapid resolution liquid chromatography-tandem mass spectrometry

A novel multiresidue analysis method is developed for highly sensitive and simultaneous determination of 16 sulphonamides (SAs), 4 acetyled metabolites, and trimethoprim in pork and mutton by rapid resolution liquid chromatography-tandem mass spectrometry (RRLC-MS/MS). The sample was extracted with acetonitrile under ultrasonication incubation, followed by solid phase extraction (SPE). The calibration curves showed good linearity with correlation coefficient (r) more than 0.998. The limit of quantification (LOQ) was 0.35–1.0 μg/kg, which can ensure to detect studied drugs at the maximum residue level (MRL) of 10 μg/kg. The mean recoveries at addition level of 1.0, 5.0 and 50 μg/kg were in the range of 68.3–104% with the relative standard deviation (RSD) of 3.5–9.2%. The intra-day precision (as RSD) for six determinations at 50 μg/kg spiked level within a day was in the range of 4.2–8.9%. The method is sensitive, accurate, convenient and rapid, and can be used for the qualitatively and quantitatively determination of multiresidue of the studied drugs in meat.

The occurrence of antibiotics in an urban watershed: From wastewater to drinking water

The presence of 28 antibiotics in three hospital effluents, five wastewater treatment plants (WWTPs), six rivers and a drinking water storage catchment were investigated within watersheds of South–East Queensland, Australia. All antibiotics were detected at least once, with the exception of the polypeptide bacitracin which was not detected at all. Antibiotics were found in hospital effluent ranging from 0.01–14.5 μg L − 1 , dominated by the β-lactam, quinolone and sulphonamide groups. Antibiotics were found in WWTP influent up to 64 μg L − 1 , dominated by the β-lactam, quinolone and sulphonamide groups. Investigated WWTPs were highly effective in removing antibiotics from the water phase, with an average removal rate of greater than 80% for all targeted antibiotics. However, antibiotics were still detected in WWTP effluents in the low ng L − 1 range up to a maximum of 3.4 μg L − 1 , with the macrolide, quinolone and sulphonamide antibiotics most prevalent. Similarly, antibiotics were detected quite frequently in the low ng L − 1 range, up to 2 μg L − 1 in the surface waters of six investigated rivers including freshwater, estuarine and marine samples. The total investigated antibiotic concentration (TIAC) within the Nerang River was significantly lower ( p < 0.05) than all other rivers sampled. The absence of WWTP discharge to this river is a likely explanation for the significantly lower TIAC and suggests that WWTP discharges are a dominant source of antibiotics to investigated surface waters. A significant difference ( p < 0.001) was identified between TIACs at surface water sites with WWTP discharge compared to sites with no WWTP discharge, providing further evidence that WWTPs are an important source of antibiotics to streams. Despite the presence of antibiotics in surface waters used for drinking water extraction, no targeted antibiotics were detected in any drinking water samples.

Determination of ten sulphonamides in egg by liquid chromatography–tandem mass spectrometry

A precise and reliable method for the determination of 10 sulphonamide antibiotics (sulfadiazine, sulfathiazole, sulfamerazine, sulfamethazine, sulfamethoxypyridazine, sulfachloropyridazine, sulfamethoxazole, sulfamonomethoxine, sulfadimethoxine and sulfaquinoxaline) in egg by liquid chromatography–tandem mass spectrometry (LC–MS/MS) has been developed. Drugs were extracted using a mixture of dichloromethane/acetone (50:50, v/v), acidified with acetic acid and then cleaned-up on a cation-exchange solid-phase extraction (SPE) cartridge. The chromatographic separation was performed by gradient on a C 18 column with a mobile phase of methanol–water containing 0.1% formic acid and 5 mM ammonium acetate, then sulphonamides were detected in a triple-quadrupole mass spectrometer operated in positive electrospray ionization mode (ESI +). The method was validated at 15, 30 and 45 μg kg −1. These levels were much lower than the corresponding maximum residue limit of 100 μg kg −1 set for sulphonamides in several matrices but not in eggs, where the presence of such residues is not permitted. Results were quantitated against the selected internal standard 13C 6-sulphamethazine and also according to the matrix-matched approach. The within-laboratory reproducibility, expressed as a relative standard deviation, never exceeded 21%. All decision limit (CCα) values lied in the range between 16.1 and 20.5 μg kg −1 and the corresponding results for detection capability (CCβ) were 16.9 and 25.7 μg kg −1. Ruggedness was estimated according to the Youden robustness test.