Fluoroquinolone resistance in Neisseria gonorrhoeae after cessation of ciprofloxacin usage in San Francisco: using molecular typing to investigate strain turnover

Veterinary antibiotics differ in phytotoxicity on oilseed rape grown over a wide range of concentrations

Residues of veterinary antibiotics are a worldwide problem of increasing concern due to their persistence and diverse negative effects on organisms, including crops, and limited understanding of their phytotoxicity. Therefore, this study aimed to compare the phytotoxic effects of veterinary antibiotics tetracycline (TC) and ciprofloxacin (CIP) applied in a wide range of concentrations on model plant oilseed rape (Brassica napus). Overall phytotoxicity of 1-500 mg kg-1 of TC and CIP was investigated based on morphological, biochemical, and physiological plant response. Photosystem II (PSII) performance was suppressed by TC even under environmentally relevant concentration (1 mg kg-1), with an increasing effect proportionally to TC concentration in soil. In contrast, CIP was found to be more phytotoxic than TC when applied at high concentrations, inducing a powerful oxidative burst, impairment of photosynthetic performance, collapse of antioxidative protection and sugar metabolism, and in turn, complete growth retardation at 250 and 500 mg kg-1 CIP treatments. Results of our study suggest that TC and CIP pollution do not pose a significant risk to oilseed rapes in many little anthropogenically affected agro-environments where TC or CIP concentrations do not exceed 1 mg kg-1; however, intensive application of manure with high CIP concentrations (more than 50 mg kg-1) might be detrimental to plants and, in turn, lead to diminished agricultural production and a potential risk to human health.

Ciprofloxacin adsorption by biochar derived from co-pyrolysis of sewage sludge and bamboo waste

Antibiotics residues in aqueous environment and sewage sludge accumulation have become serious environmental issues. The aim of this study is to investigate the potential of ciprofloxacin (CIP) removal by sludge-based biochar prepared from co-pyrolysis of sewage sludge and bamboo waste (BW). The stability and environmental risk of heavy metals (HMs) in the biochar were further investigated to evaluate potential risks for biochar utilization. Results showed that BW was an outstanding additive to prepare co-pyrolyzed biochar from sludge. A higher CIP removal rate (95%) of BW-sludge biochar (SBC) was obtained under initial CIP concentration of 10 mg/L, and its maximum adsorption capacity was 62.48 mg/g which was calculated from the Langmuir model. The pseudo-second-order and Freundlich model also well fit the CIP adsorption process, indicating a chemical and multilayer adsorption of CIP on a heterogeneous surface of biochar. Adsorption mechanism analysis indicated that the diverse functional groups and Fe species in biochar probably were the dominant factors in the adsorption of CIP. The π-π interaction, H-bond, ion exchange, and Fe-complexation might be the main interactions between the functional species and CIP molecules. Besides, HMs, especially the Cr, Cd, and As, were well immobilized in SBC compared with pure sludge biochar. This work suggested that sludge-based biochar, especially the co-pyrolyzed SBC, could be a potential adsorbent for CIP removal from aqueous solutions.

Adsorption of ciprofloxacin and Cu2+ onto biochars in the presence of dissolved organic matter derived from animal manure

Biochar are widely used as adsorbents/amendments for immobilizing pollutants in contaminated soils. In this study, the effects of dissolved organic matter derived from chicken manure (CMDOM) on the adsorption of ciprofloxacin (CIP) and Cu²⁺ onto biochars were investigated. The FTIR spectra indicated that π-π donor-acceptor interactions between the hydroxyl groups on the biochar surface and the fluorine group connected to the benzene ring of CIP molecule was the main adsorption mechanism for CIP. CMDOM molecules interacted with the aromatic components in biochars and thus modified the surface chemical properties of biochar. The effect of CMDOM on the adsorption of CIP onto biochars showed great dependence on the distribution of solid adsorbed CMDOM and CMDOM in aqueous solutions. The solid adsorbed CMDOM facilitated CIP adsorption owing to increase the content of -OH on biochar surface, which could provide more π-electron donors and thus strengthened π-π EDA interactions between CIP and biochars. The EDS spectra showed that the ion exchange with K⁺ was the main adsorption mechanism for Cu²⁺ onto biochars, and the presence of CMDOM enhanced complexation of Cu²⁺ with adsorbed CMDOM, thus increasing Cu²⁺ adsorption onto biochars. These results are useful for the application of biochars to immobilize antibiotic and heavy metals in contaminated farmland soils when animal manure fertilizers is presented in soil environment.

Municipal solid waste biochar-bentonite composite for the removal of antibiotic ciprofloxacin from aqueous media

This study investigates the adsorption of ciprofloxacin (CPX) onto a municipal solid waste derived biochar (MSW-BC) and a composite material developed by combining the biochar with bentonite clay. A bentonite-MSW slurry was first prepared at 1:5 ratio (w/w), and then pyrolyzed at 450 °C for 30 min. The composite was characterized by scanning electron microscopy (SEM), Powder X-ray diffraction (PXRD) and Fourier transform infrared (FTIR) spectroscopy before and after CPX adsorption. Batch experiments were conducted to assess the effect of pH, reaction time and adsorbate dosage. The SEM images confirmed successful modification of the biochar with bentonite showing plate like structures. The PXRD patterns showed changes in the crystalline lattice of both MSW-BC and the composite before and after CPX adsorption whereas the FTIR spectra indicated merging and widening of specific bands after CPX adsorption. The optimum CPX adsorption was achieved at pH 6, and the maximum adsorption capacity of the composite calculated via isotherm modeling was 190 mg/g, which was about 40% higher than the pristine MSW-BC. The Hill isotherm model along with pseudo-second order and Elovich kinetic models showed the best fit to the adsorption data. The most plausible mechanism for increased adsorption capacity is the increased active sites of the composites for CPX adsorption through induced electrostatic interactions between the functional groups of the composite and CPX molecules. The added reactive surfaces in the composite because of bentonite incorporation, and the intercalation of CPX in the clay interlayers improved the adsorption of CPX by the biochar-bentonite composite compared to the pristine biochar. Thus, MSW-BC-bentonite composites could be considered as a potential material for remediating pharmaceuticals in aqueous media.

Study of ciprofloxacin removal by biochar obtained from used tea leaves

In this study, used tea leaves (UTLs) were pyrolyzed to obtain used tea-leaf biochar (UTC), and then the UTC was used as an adsorbent to remove ciprofloxacin (CIP) from aqueous solutions. Batch experiments were conducted to investigate the CIP adsorption performance and mechanism. The results showed that the CIP-adsorbing ability first increased and then declined as the UTC pyrolysis temperature increased. The UTC obtained at 450°C presented excellent CIP-absorbing ability at pH6 and 40°C. The maximum monolayer adsorption capacity was 238.10mg/g based on the Langmuir isotherm model. The pseudo-second-order kinetic equation agreed well with the CIP adsorption process, which was controlled by both external boundary layer diffusion and intra-particle diffusion. The characterization analysis revealed that the OH groups, CC bonds of aromatic rings, CH groups in aromatic rings and phenolic CO bonds play vital roles in the CIP adsorption process, and that the NC, NO, OCO and COH groups of UTC were consumed in large quantities. π-π interactions, hydrogen bonding and electrostatic attraction are inferred as the main adsorption mechanisms. The present work provides not only a feasible and promising approach for UTLs utilization but also a potential adsorbent material for removing high concentrations of CIP from aqueous solutions.

Repurposing an old drug: aztreonam as a new treatment strategy for gonorrhoea

Objectives

To determine whether aztreonam is still an effective drug for the treatment of gonorrhoea.

Methods

Observational study of patients with gonorrhoea diagnosed by urine multiplex PCR, with a past medical history of allergy to β-lactams or relapse after treatment with a third-generation cephalosporin. Patients received a single 1 g dose of aztreonam in accordance with the manufacturer's instructions.

Results

Five patients (four males, one female) were enrolled, comprising two who were allergic to β-lactams and three previously treated with cephalosporins who relapsed. Median age was 38 years (range 23-51). Following treatment with aztreonam all were cured without any adverse event. All the men were free of symptoms, and the woman tested negative for gonorrhoea 1 month after treatment.

Conclusion

Aztreonam appears to be an effective alternative to cephalosporins in the treatment of uncomplicated gonorrhoea, particularly when patients are suspected of being infected by strains with reduced susceptibility to ceftriaxone or are known to be allergic to penicillin.

Antimicrobial resistance of Neisseria gonorrhoeae isolates in south-west Germany, 2004 to 2015: increasing minimal inhibitory concentrations of tetracycline but no resistance to third-generation cephalosporins

Increasing antimicrobial resistance of Neisseria gonorrhoeae, particularly to third-generation cephalosporins, has been reported in many countries. We examined the susceptibility (determined by Etest and evaluated using the breakpoints of the European Committee on Antimicrobial Susceptibility Testing) of 434 N. gonorrhoeae isolates collected from 107 female and 327 male patients in Stuttgart, south-west Germany, between 2004 and 2015. During the study period, high proportions of isolates were resistant to ciprofloxacin (70.3%), tetracycline (48.4%; increasing from 27.5% in 2004/2005 to 57.7% in 2014/2015; p = 0.0002) and penicillin (25.6%). The proportion of isolates resistant to azithromycin was low (5.5%) but tended to increase (p = 0.08). No resistance and stable minimum inhibitory concentrations were found for cefixime, ceftriaxone, and spectinomycin. High-level resistance was found for ciprofloxacin (39.6%) and tetracycline (20.0%) but not for azithromycin; 16.3% of the isolates produced betalactamase. Thus, cephalosporins can still be used for the treatment of gonorrhoea in the study area. To avoid further increasing resistance to azithromycin, its usage should be limited to patients allergic to cephalosporins, or (in combination with cephalosporins) to patients for whom no susceptibility testing could be performed or those co-infected with chlamydiae.

Performance and Verification of a Real-Time PCR Assay Targeting the gyrA Gene for Prediction of Ciprofloxacin Resistance in Neisseria gonorrhoeae

In the United States, 19.2% of Neisseria gonorrhoeae isolates are resistant to ciprofloxacin. We evaluated a real-time PCR assay to predict ciprofloxacin susceptibility using residual DNA from the Roche Cobas 4800 CT/NG assay. The results of the assay were 100% concordant with agar dilution susceptibility test results for 100 clinical isolates. Among 76 clinical urine and swab specimens positive for N. gonorrhoeae by the Cobas assay, 71% could be genotyped. The test took 1.5 h to perform, allowing the physician to receive results in time to make informed clinical decisions.

Ciprofloxacin adsorption on graphene and granular activated carbon: kinetics, isotherms, and effects of solution chemistry

Ciprofloxacin (CIP) is a commonly used antibiotic and widely detected in wastewaters and farmlands nowadays. This study evaluated the efficacy of next-generation adsorbent (graphene) and conventional adsorbent (granular activated carbon, GAC) for CIP removal. Batch experiments and characterization tests were conducted to investigate the adsorption kinetics, equilibrium isotherms, thermodynamic properties, and the influences of solution chemistry (pH, ionic strength, natural organic matter (NOM), and water sources). Compared to GAC, graphene showed significantly faster adsorption and reached equilibrium within 3 min, confirming the rapid access of CIP into the macroporous network of high surface area of graphene as revealed by the Brunner-Emmet-Teller measurements analysis. The kinetics was better described by a pseudo-second-order model, suggesting the importance of the initial CIP concentration related to surface site availability of graphene. The adsorption isotherm on graphene followed Langmuir model with a maximum adsorption capacity of 323 mg/g, which was higher than other reported carbonaceous adsorbents. The CIP adsorption was thermodynamically favourable on graphene and primarily occurred through π - π interaction, according to the FTIR spectroscopy. While the adsorption capacity of graphene decreased with increasing solution pH due to the speciation change of CIP, the adverse effects of ionic strength (0.01-0.5 mol L(-1)), presence of NOM (5 mg L⁻¹), and different water sources (river water or drinking water) were less significant on graphene than GAC. These results indicated that graphene can serve as an alternative adsorbent for CIP removal in commonly encountered field conditions, if proper separation and recovery is available in place.