Reduced graphene oxide promotes the biodegradation of sulfamethoxazole by white-rot fungus Phanerochaete chrysosporium under cadmium stress.

The biodegradation of antibiotics in aquatic environment is consistently impeded by the widespread presence of heavy metals, necessitating urgent measures to mitigate or eliminate this environmental stress. This work investigated the degradation of sulfamethoxazole (SMX) by the white-rot fungus Phanerochaete chrysosporium (WRF) under heavy metal cadmium ion (Cd2+) stress, with a focus on the protective effects of reduced graphene oxide (RGO). The pseudo-first-order rate constant and removal efficiency of 5 mg/L SMX in 48 h by WRF decrease from 0.208 h-1 and 55.6% to 0.08 h-1 and 28.6% at 16 mg/L of Cd2+, while these values recover to 0.297 h-1 and 72.8% by supplementing RGO. The results demonstrate that RGO, possessing excellent biocompatibility, effectively safeguard the mycelial structure of WRF against Cd2+ stress and provide protection against oxidative damage to WRF. Simultaneously, the production of manganese peroxidase (MnP) by WRF decreases to 38.285 U/L in the presence of 24 mg/L Cd2+, whereas it recovers to 328.51 U/L upon the supplement of RGO. RGO can induce oxidative stress in WRF, thereby stimulating the secretion of laccase (Lac) and MnP to enhance the SMX degradation. The mechanism discovered in this study provides a new strategy to mitigate heavy metal stress encountered by WRF during antibiotic degradation.

Enhanced sulfonamides removal via microalgae-bacteria consortium via co-substrate supplementation.

Both co-cultivation and co-substrate addition strategies have exhibited massive potential in microalgae-based antibiotic bioremediation. In this study, glucose and sodium acetate were employed as co-substrate in the cultivation of microalgae-bacteria consortium for enhanced sulfadiazine (SDZ) and sulfamethoxazole (SMX) removal. Glucose demonstrated a two-fold increase in biomass production with a maximum specific growth rate of 0.63 ± 0.01 d-1 compared with sodium acetate. The supplementation of co-substrate enhanced the degradation of SDZ significantly up to 703 ± 18% for sodium acetate and 290 ± 22% for glucose, but had almost no effect on SMX. The activities of antioxidant enzymes, including peroxidase, superoxide dismutase and catalase decreased with co-substrate supplementation. Chlorophyll a was associated with protection against sulfonamides and chlorophyll b might contribute to SDZ degradation. The addition of co-substrates influenced bacterial community structure greatly. Glucose enhanced the relative abundance of Proteobacteria, while sodium acetate improved the relative abundance of Bacteroidetes significantly.

Proteomic mechanisms for the stimulatory effects of antibiotics on Microcystis aeruginosa during hydrogen peroxide treatment.

Application of low dosage of H2O2 at early stage of cyanobacterial life cycle is a promising route for cyanobacterial bloom mitigation, which could minimize adverse effects on non-target organisms. Besides, influence of co-existing contaminants on cyanobacterial bloom mitigation under combined pollution conditions remains unclear. This study assessed the influence of a mixture of four frequently detected antibiotics (tetracycline, sulfamethoxazole, ciprofloxacin and amoxicillin) during H2O2 treatment of Microcystis aeruginosa at early growth stage. H2O2 significantly (p < 0.05) inhibited growth rate, chlorophyll a content, Fv/Fm and rETRmax in a dose-dependent manner at low doses of 0.25-1 mg L-1, through downregulating proteins involved in cell division, cellular component organization, gene expression and photosynthesis. Although H2O2 increased microcystin content in each cyanobacterial cell through the upregulation of microcystin synthetases (mcyC and mcyF), total microcystin concentration in H2O2 treated groups was significantly (p < 0.05) reduced due to the decrease of cell density. Existence of 80 and 200 ng L-1 mixed antibiotics during H2O2 treatment facilitated the scavenging of ROS by antioxidant enzymes and significantly (p < 0.05) stimulated growth, photosynthesis, microcystin synthesis and microcystin release in H2O2 treated cells, through the upregulation of proteins involved in photosynthesis, oxidation-reduction process, biosynthesis, gene expression and transport. Mixed antibiotics increased the hazard of M. aeruginosa during H2O2 treatment, through the stimulation of microcystin synthesis and release at the proteomic level. Each target antibiotic should be controlled below 5 ng L-1 before the application of H2O2 for eliminating the interference of antibiotics on cyanobacterial bloom mitigation.

Effects of sulfamethoxazole and sulfamethoxazole-degrading bacteria on water quality and microbial communities in milkfish ponds.

Intensive farming practices are typically used for aquaculture. To prevent disease outbreaks, antibiotics are often used to reduce pathogenic bacteria in aquaculture animals. However, the effects of antibiotics on water quality and microbial communities in euryhaline fish culture ponds are largely unknown. The aim of this study was to investigate the interactions between sulfamethoxazole (SMX), water quality and microbial communities in milkfish (Chanos chanos) culture ponds. The results of small-scale milkfish pond experiments indicated that the addition of SMX decreased the abundance of ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB) and photosynthetic bacteria. Consequently, the levels of ammonia and total phosphorus in the fish pond water increased, causing algal and cyanobacterial blooms to occur. In contrast, the addition of the SMX-degrading bacterial strains A12 and L effectively degraded SMX and reduced the levels of ammonia and total phosphorus in fish pond water. Furthermore, the abundances of AOB, NOB and photosynthetic bacteria were restored, and algal and cyanobacterial blooms were inhibited. This study demonstrate the influences of SMX on water quality and microbial community composition in milkfish culture ponds. Moreover, the use of the bacterial strains A12 and L as dual function (bioaugmentation and water quality maintenance) beneficial bacteria was shown to provide an effective approach for the bioremediation of SMX-contaminated euryhaline milkfish culture ponds.

Microbial population shift caused by sulfamethoxazole in engineered-Soil Aquifer Treatment (e-SAT) system.

The engineered-Soil Aquifer Treatment (e-SAT) system was exploited for the biological degradation of Sulfamethoxazole (SMX) which is known to bio-accumulate in the environment. The fate of SMX in soil column was studied through laboratory simulation for a period of 90 days. About 20 ppm SMX concentration could be removed in four consecutive cycles in e-SAT. To understand the microbial community change and biological degradation of SMX in e-SAT system, metagenomic analysis was performed for the soil samples before (A-EBD) and after SMX exposure (B-EBD) in the e-SAT. Four bacterial phyla were found to be present in both the samples, with sample B-EBD showing increased abundance for Actinobacteria, Bacteroidetes, Firmicutes and decreased Proteobacterial abundance compared to A-EBD. The unclassified bacteria were found to be abundant in B-EBD compared to A-EBD. At class level, classes such as Bacilli, Negativicutes, Deltaproteobacteria, and Bacteroidia emerged in sample B-EBD owing to SMX treatment, while Burkholderiales and Nitrosomonadales appeared to be dominant at order level after SMX treatment. Furthermore, in response to SMX treatment, the family Nitrosomonadaceae appeared to be dominant. Pseudomonas was the most dominating bacterial genus in A-EBD whereas Cupriavidus dominated in sample B-EBD. Additionally, the sulfur oxidizing bacteria were enriched in the B-EBD sample, signifying efficient electron transfer and hence organic molecule degradation in the e-SAT system. Results of this study offer new insights into understanding of microbial community shift during the biodegradation of SMX.

Evaluation of sulfonamide detoxification pathways in haematologic malignancy patients prior to intermittent trimethoprim-sulfamethoxazole prophylaxis.

AIMS: Patients with haematologic malignancies have a reportedly high incidence of sulfamethoxazole (SMX) hypersensitivity. The objective of this study was to determine whether deficiencies in sulfonamide detoxification pathways, to include glutathione (GSH) and ascorbate (AA), and cytochrome b(5) (b5) and cytochrome b(5) reductase (b5R), were prevalent in these patients. A secondary pilot objective was to determine whether the incidence of drug hypersensitivity following intermittent trimethoprim-SMX (TMP-SMX) prophylaxis approached that reported for high dose daily regimens. METHODS: Forty adult patients with haematologic malignancies (HM) and 35 healthy adults were studied; an additional 13 HM patients taking ascorbate supplements (HM-AA) were also evaluated. Twenty-two of 40 HM patients were prescribed and were compliant with TMP-SMX 960 mg three to four times weekly. RESULTS: There were no significant differences between HM and healthy groups in plasma AA (median 37.2 µm vs. 33.9 µm) or red blood cell GSH (1.9 mmvs. 1.8 mm). However, plasma AA was correlated significantly with leucocyte b5/b5R reduction (r= 0.39, P= 0.002). Deficient b5/b5R activities were not found in HM patients. In fact, patients with chronic lymphocytic leukaemia or myeloma had significantly higher median activities (80.7 µmol mg(-1) min(-1)) than controls (18.9 µmol mg(-1) min(-1), P= 0.008). After 3-4 weeks of treatment, no patients developed SMX-specific T cells and only one patient developed rash. CONCLUSIONS: Deficiencies of blood antioxidants and b5/b5R reduction were not found in this population with haematologic malignancies, and the development of skin rash and drug-specific T cells appeared to be uncommon with intermittent TMP-SMX prophylaxis.

Roles of endogenous ascorbate and glutathione in the cellular reduction and cytotoxicity of sulfamethoxazole-nitroso.

Sulfamethoxazole (SMX) is an effective drug for the management of opportunistic infections, but its use is limited by hypersensitivity reactions, particularly in HIV-infected patients. The oxidative metabolite SMX-nitroso (SMX-NO), is thought to be a proximate mediator of SMX hypersensitivity, and can be reduced in vitro by ascorbate or glutathione. Leukocytes from patients with SMX hypersensitivity show enhanced cytotoxicity from SMX metabolites in vitro; this finding has been attributed to a possible "detoxification defect" in some individuals. The purpose of this study was to determine whether variability in endogenous ascorbate or glutathione could be associated with individual differences in SMX-NO cytotoxicity. Thirty HIV-positive patients and 23 healthy control subjects were studied. Both antioxidants were significantly correlated with the reduction of SMX-NO to its hydroxylamine, SMX-HA, by mononuclear leukocytes, and both were linearly depleted during reduction. Controlled ascorbate supplementation in three healthy subjects increased leukocyte ascorbate with no change in glutathione, and significantly enhanced SMX-NO reduction. Ascorbate supplementation also decreased SMX-NO cytotoxicity compared to pre-supplementation values. Rapid reduction of SMX-NO to SMX-HA was associated with enhanced direct cytotoxicity from SMX-NO. When forward oxidation of SMX-HA back to SMX-NO was driven by the superoxide dismutase mimetic, Tempol, SMX-NO cytotoxicity was increased, without enhancement of adduct formation. This suggests that SMX-NO cytotoxicity may be mediated, at least in part, by redox cycling between SMX-HA and SMX-NO. Overall, these data indicate that endogenous ascorbate and glutathione are important for the intracellular reduction of SMX-NO, a proposed mediator of SMX hypersensitivity, and that redox cycling of SMX-HA to SMX-NO may contribute to the cytotoxicity of these metabolites in vitro.

Plasma ascorbate deficiency is associated with impaired reduction of sulfamethoxazole-nitroso in HIV infection.

OBJECTIVE: The objective of these studies was to determine the role of ascorbate deficiency in HIV infection in the defective detoxification of sulfamethoxazole-nitroso, the metabolite thought to mediate sulfonamide hypersensitivity reactions. METHODS: Fifty-one HIV-infected patients and 26 healthy volunteers were evaluated. Vitamin supplementation histories were obtained, and blood samples were collected for determination of plasma ascorbate, dehydroascorbate, and cysteine concentrations, erythrocyte glutathione concentrations, and plasma reduction of sulfamethoxazole-nitroso in vitro. RESULTS: Plasma ascorbate concentrations were significantly lower in HIV-positive patients not taking vitamin supplements (29.5 +/- 22.3 microM) than in healthy subjects (54.8 +/- 22.3 microM; P = 0.0005) and patients taking 500-1000 mg of ascorbate daily (82.5 +/- 26.3 microM; P < 0.0001). Plasma ascorbate deficiency was strongly correlated with impaired reduction of sulfamethoxazole-nitroso to its hydroxylamine (r = 0.60, P < 0.0001), and during in vitro reduction, the loss of plasma ascorbate was strongly associated with the amount of nitroso reduced (r = 0.70, P < 0.0001). Ascorbate added ex vivo normalized this reduction pathway. Erythrocyte glutathione concentrations were significantly lower in HIV-positive patients (0.98+/-0.32 mM) than in healthy subjects (1.45+/-0.49 mM; P = 0.001), but this finding was unrelated to ascorbate supplementation. There was trend toward lower plasma cysteine concentrations in patients (8.4+/-3.9 microM) than in controls (10.3+/-4.3 microM), but this trend was similarly unrelated to ascorbate supplementation. Dehydroascorbate concentrations were not significantly higher in HIV-positive patients (7.4+/-10.5%) than in healthy controls (4.0+/-6.2%), even in the subset of patients taking ascorbate (8.4+/-9.4%). CONCLUSIONS: Ascorbate deficiency is common in HIV-positive patients and is associated with impaired detoxification of sulfamethoxazole-nitroso, the suspected proximate toxin in sulfonamide hypersensitivity. Patients taking daily ascorbate supplements (500-1000 mg) achieved high plasma ascorbate concentrations and did not show this detoxification defect. Ascorbate deficiency (or supplementation) was not associated with changes in glutathione or cysteine concentrations. These data suggest that ascorbate deficiency, independent of thiol status, may be an important determinant of impaired drug detoxification in HIV infection.

The disposition of five therapeutically important antimicrobial agents in llamas.

The disposition of five therapeutic antimicrobial agents was studied in llamas (Lama glama) following intravenous bolus administration. Six llamas were each given ampicillin, tobramycin, trimethoprim, sulfamethoxazole, enrofloxacin and ceftiofur at a dose of 12 mg/kg, 1 mg/kg, 3 mg/kg, 15 mg/kg, 5 mg/kg, and 2.2 mg/kg of body weight, respectively, with a wash out period of at least 3 days between treatments. Plasma concentrations of these antimicrobial agents over 12 h following i.v. bolus dosing were determined by reverse phase HPLC. Disposition of the five antimicrobial agents was described by a two compartment open model with elimination from the central compartment, and also by non-compartmental methods. From compartmental analysis, the elimination rate constant, half-life, and apparent volume of distribution in the central compartment were determined. Statistical moment theory was used to determine noncompartmental pharmacokinetic parameters of mean residence time, clearance, and volume of distribution at steady state. Based on the disposition parameters determined, and stated assumptions of likely effective minimum inhibitory concentrations (MIC) a dose and dosing interval for each of five antimicrobial agents were suggested as 6 mg/kg every 12 h for ampicillin; 4 mg/kg once a day or 0.75 mg/kg every 8 h for tobramycin; 3.0 mg/kg/15 mg/kg every 12 h for trimethoprim/sulfamethoxazole; 5 mg/kg every 12 h for enrofloxacin; and 2.2 mg/kg every 12 h for ceftiofur sodium for llamas. Steady-state peak and trough plasma concentrations were also predicted for the drugs in this study for llamas.

Effect of pectin and kaolin on bioavailability of co-trimoxazole suspension.

Bioavailability of co-trimoxazole suspension was determined with and without concurrent administration of pectin and kaolin in 8 volunteers. Twenty ml suspension of co-trimoxazole containing 160 mg trimethoprim (TMP) and 800 mg sulphamethoxazole (SMX) and co-trimoxazole suspension along with 20 ml of pectin-kaolin suspension were administered in a random order with 7 days interval. Plasma estimation of trimethoprim and sulphonamide was carried out at serial intervals. Area under curve (AUC) and Cmax of TMP were significantly higher when co-trimoxazole suspension alone was used. No statistically significant changes were observed in case of sulphamethoxazole. Clinical study is necessary to verify whether concurrent administration of co-trimoxazole and pectin-kaolin leads to loss of antibacterial efficacy.

A comparative study of cefadroxil and co-trimoxazole in patients with lower respiratory tract infections.

The most common causative pathogens in lower respiratory disease are S. pneumoniae, H. influenzae and S. pyogenes. Cefadroxil and co-trimoxazole, both orally administered broad spectrum antibiotics, are effective against these organisms when given in a twice-daily regimen. In this open randomised study, 42 patients with lower respiratory tract infections received cefadroxil 1 g or co-trimoxazole 1 double-strength tablet every 12 hours for a mean duration of 11 and 13 days, respectively. Pathogens were isolated in the pre-treatment sputum of 51% of patients given cefadroxil and in 25% of those who received co-trimoxazole. Similar overall cure rates were observed after treatment with cefadroxil (67%) and co-trimoxazole (60%); sputum purulence was similarly diminished by both drugs (91% and 85%, respectively). Neither antibiotic caused serious side effects. Thus, in a convenient twice-daily regimen, cefadroxil and co-trimoxazole are comparably effective in treating lower respiratory tract infections.

Significance of the sulfonamide component for the clinical efficacy of trimethoprim-sulfonamide combinations.

The reasons for combining trimethoprim (TMP) with sulfonamides (SUL) are still mainly theoretical but are supported by results from experimental infections and treatment of specific pathogens in humans, such as Branhamella catarrhalis, Neisseria gonorrhoeae, Brucella, Nocardia asteroides and perhaps Bordetella pertussis and Chlamydia trachomatis. Addition of SUL to TMP confers a therapeutic advantage also in patients with complicated urinary tract infection but probably not in young women with acute cystitis. Conditions that may enable TMP-SUL synergy in vivo can be expected to occur only in occasional cases of infection due to staphylococci, streptococci, Haemophilus or enteric bacteria. This fact together with ethical problems and availability of alternative therapies make further evaluations of the clinical significance of the SUL component of TMP-SUL very difficult. Although the use of TMP alone has shown promise in exacerbations of chronic bronchitis the role of the SUL component in TMP-SUL treatment of infections outside the urinary tract remains to be defined in comparative clinical trials.

Antibacterial activity of phosphanilic acid, alone and in combination with trimethoprim.

We explored the antibacterial activity of phosphanilic acid (P), an analog of sulfanilic acid, alone and in combination with trimethoprim (T; TP, 1:5) with sulfamethoxazole (S) and co-trimoxazole, the combination of this sulfonamide with trimethoprim (TS, 1:5) as the reference. P resembled S in spectrum but, in addition, had significant activity against Pseudomonas aeruginosa. The overall frequency and degree of synergism with TP were lower than with co-trimoxazole. P, like S, was strongly affected by changes in inoculum size and was not bactericidal. P was well absorbed parenterally but not orally in mice. Despite low (but prolonged) blood levels, P, given orally to mice, was effective in treating infections caused by P. aeruginosa. However, against most experimental infections the therapeutic effectiveness of P, as well as that of TP, administered either intramuscularly or orally was unimpressive. Based on in vivo data, the therapeutic application of P or TP would appear to be limited.

Trimethoprim-sulfamethoxazole for bacterial meningitis.

Trimethoprim-sulfamethoxazole has excellent microbiologic activity against most pathogens that produce meningitis; both components of this drug have high penetration into tissues, including the cerebrospinal fluid. Clinical experience shows that trimethoprim-sulfamethoxazole may be beneficial in the treatment of gram-negative bacillary meningitis caused by organisms only moderately susceptible to third-generation cephalosporins (Enterobacter cloacae, Serratia marcescens) or resistant to these antibiotic agents (Pseudomonas cepacia, Acinetobacter). The success of trimethoprim-sulfamethoxazole in the treatment of four patients with Staphylococcus aureus and two patients with Listeria monocytogenes meningitis shows that this drug may also be useful in treating infrequent types of gram-positive meningitis.

Urinary tract infections: the efficacy of trimethoprim/sulfamethoxazole.

The diagnosis of bacterial urinary infections is reasonably exact and routine in medical practice. In contrast, therapeutic regimens have been arbitrary with little rationale and no relationship to infection site or therapeutic objective. During the past decades a series of careful prospective studies have carefully characterized episodes of infection to the site within the urinary tract, and adequate follow-up has been obtained to determine the pattern of response. This has led to the emergence of definite guidelines on dose and duration for antimicrobial therapy. The antimicrobial combination of trimethoprim and sulfamethoxazole has been employed in many of these studies and has been found to be a particularly effective agent for both the treatment and prevention of urinary infections. These studies and their implications for optimal treatment of urinary infections are reviewed.

Secretion of various antimicrobial substances in dogs with experimental bacterial prostatitis.

Bacterial prostatitis in dogs was induced by injection of an E. coli 06 suspension into a branch of the prostatic artery. Three to six days later, secretion from the inflamed glands was obtained by pilocarpine stimulation and the concentrations of trimethoprim, sulphamethoxazole, erythromycin, doxycycline and ampicillin were measured during constant infusion of these drugs. In the prostatic secretion, only the concentrations of the lipid soluble substances trimethoprim and erythromycin exceeded the corresponding plasma levels. These two substances may therefore be of value in the treatment of bacterial prostatitis.