Topical chloramphenicol and the risk of acute leukaemia in adults

Triple-Helix Molecular Switch Triggered Cleavage Effect of DNAzyme for Ultrasensitive Electrochemical Detection of Chloramphenicol

The abuse of chloramphenicol (CAP) in animal-derived products leads to serious food safety problems, so the sensitive and accurate determination of CAP residues has great noteworthiness for public health. Herein, we present a novel electrochemical aptasensor that incorporates a poly(diallyldimethylammonium chloride) functionalized graphene/Ag@Au nanosheets (PDDA-Gr/Ag@Au NSs) composite modified electrode and a DNAzyme signal amplification effect triggered by a triple-helix molecular switch (THMS) for detecting CAP. The PDDA-Gr/Ag@Au NSs composite has the advantages of high surface area, great conductivity, and dispersibility and has successfully improved the electrochemical performance of the electrode. Specific interaction with CAP will cause the signal transduction probe (STP) to be released from the THMS. After that, the DNAzyme will be activated with the help of Pb²⁺ and remove the immobilized signal probe on the electrode surface. The signal change was recorded by square wave voltammetry (SWV) and led to an accurate quantification of CAP. With all these features, the proposed sensing strategy yielded a satisfactory analytical performance with linearity between 1 pM and 1 μM and a limit of detection of 18.6 fM. Furthermore, the aptasensor shows excellent specificity for CAP in the presence of other antibiotics and resists interference with other common metal ions. Importantly, the performance is not diminished when the constructed aptasensor is applied to measuring CAP in milk powder. This THMS-based method is easy to design, and alteration to different targets can be achieved by simply replacing the aptamer sequence in the THMS. Therefore, this method shows significant prospects as a flexible platform for accurate monitoring of antibiotic residues in foodstuffs.

Exonuclease III-Driven Dual-Amplified Electrochemical Aptasensor Based on PDDA-Gr/PtPd@Ni-Co Hollow Nanoboxes for Chloramphenicol Detection

Herein, a hierarchically porous Zr-MOF-labeled electrochemical aptasensor based on the composite of PtPd@Ni-Co hollow nanoboxes (PtPd@Ni-Co HNBs) and poly (diallyldimethylammonium chloride)-functionalized graphene (PDDA-Gr) was developed for ultrasensitive detection of chloramphenicol (CAP). PtPd@Ni-Co HNBs have excellent conductivity and provide binding sites for aptamers; the functionalized PDDA-Gr improves its dispersibility and conductivity as a substrate material, which can be successfully used to increase the electrode surface area and support more PtPd@Ni-CoHNBs. Besides, hierarchically porous Zr-MOFs (HP-UiO-66) were utilized as signal probes and showed a stronger load capacity for signal molecules than conventional UiO-66. In the presence of CAP, two ingeniously designed Exo III-assisted cyclic amplification strategies further improved the sensitivity of the aptasensor: CAP causes cycle I to release a large amount of trigger DNA (Tr DNA), and then, Tr DNA initiated cycle II, which causes the exposed capture DNA to further bind the signal probes. With these advantages, the constructed aptasensors performed with satisfactory sensitivity in a wide linear range (10 fM-10 nM) and a detection limit of 0.985 fM. Several signal amplification strategies adopted in this study have effectively improved the performance of the sensor, providing a new avenue for the development of ultrasensitive sensors in the food analysis field.

An electrochemical aptasensor based on PEI-C3N4/AuNWs for determination of chloramphenicol via exonuclease-assisted signal amplification

An electrochemical aptasensor, including the polyethyleneimine-graphite-like carbon nitride/Au nanowire nanocomposite (PEI-C₃N₄/AuNWs) and exonuclease-assisted signal amplification strategy was constructed for the determination of chloramphenicol (CAP). Initially, a nanocomposite with substantial electrocatalytic property was synthesized by PEI-C₃N₄/AuNWs. This improves the conductivity and specific surface area of the PEI-C₃N₄/AuNW-modified gold electrode. Next, a DNA with a complementary sequence to a CAP aptamer (cDNA) was immobilized on the PEI-C₃N₄/AuNW-modified electrode, followed by the CAP aptamer hybridized with cDNA. The lower signal at this time is due to the negatively charged phosphate group of the oligonucleotide and [Fe (CN)₆]^3-/4- electrostatically repelling each other. The presence of the CAP would cause aptamer on the electrode surface to fall off and be digested by Recjf exonuclease, which resulted in target recycling, and a significant increase in DPV signal can be observed at a potential of 0.176 V (vs. Ag/AgCl). Under optimal conditions, there is a linear relationship between the peak current and the logarithm of CAP concentration in the range 100 fM-1 μM, and the detection limit of this aptasensor is 2.96 fM (S/N = 3). Furthermore, the resultant aptasensor has excellent specificity, reproducibility, and long-term stability, and has been applied to the detection of CAP in milk samples. Graphical abstract The detection principle of the electrochemical aptasensor for CAP detection was based on PEI-C₃N₄/AuNWs and exonuclease-assistant signal amplification. It is based on the fact that PEI-C3N4/AuNWs nanocomposites on the surface of the electrode can effectively improve the performance of the aptasensor, and Recjf exonuclease initiates the target recycling process, causes signal amplification.

Efficacy and adverse effects of topical chloramphenicol ointment use for surgical wounds: a systematic review

BACKGROUND

Chloramphenicol ointment is often used in plastic and dermatologic surgery as a topical antibiotic for surgical wounds, but evidence regarding its efficacy and side effects is lacking. In addition, anecdotal fear of aplastic anaemia exists from the oral use of this drug. We performed a systematic review of the literature to assess the efficacy and side effect profile of topical chloramphenicol ointment on non-ocular surgical wounds.

METHODS

A systematic search of MEDLINE, EMBASE and the Cochrane Library from inception until 4 September 2017 was undertaken. Clinical studies of topical chloramphenicol ointment use on surgical wounds were included. Studies looking only at ocular use or those not available in full text or English were excluded. The review was conducted adhering to PRISMA guidelines.

RESULTS

After full-text review, five articles were included. Two were randomized controlled trials, one was retrospective case control and two were case studies. There was evidence that chloramphenicol ointment use on surgical wounds produced a non-statistically significant reduction in infection rates. Delayed hypersensitivity and acute oesophagitis were noted as potential side effects of non-ocular topical use. Aplastic anaemia was not reported.

CONCLUSION

There is a paucity of clinical data regarding the use of topical chloramphenicol ointment on surgical wounds. Further randomized controlled trials may be beneficial in order to support or refute its use in this setting.

Novel label-free and high-throughput microchip electrophoresis platform for multiplex antibiotic residues detection based on aptamer probes and target catalyzed hairpin assembly for signal amplification

Novel label-free and multiplex aptasensors have been developed for simultaneous detection of several antibiotics based on a microchip electrophoresis (MCE) platform and target catalyzed hairpin assembly (CHA) for signal amplification. Kanamycin (Kana) and oxytetracycline (OTC) were employed as models for testing the system. These aptasensors contained six DNA strands termed as Kana aptamer-catalysis strand (Kana apt-C), Kana inhibit strand (Kana inh), OTC aptamer-catalysis strand (OTC apt-C), OTC inhibit strand (OTC inh), hairpin structures H1 and H2 which were partially complementary. Upon the addition of Kana or OTC, the binding event of aptamer and target triggered the self-assembly between H1 and H2, resulting in the formation of many H1-H2 complexes. They could show strong signals which represented the concentration of Kana or OTC respectively in the MCE system. With the help of the well-designed and high-quality CHA amplification, the assay could yield 300-fold amplified signal comparing that from non-amplified system. Under optimal conditions, this assay exhibited a linear correlation in the ranges from 0.001ngmL^-1 to 10ngmL^-1, with the detection limits of 0.7pgmL^-1 and 0.9pgmL^-1 (S/N=3) toward Kana and OTC, respectively. The platform has the following advantages: firstly, the aptamer probes can be fabricated easily without labeling signal tags for MCE detection; Secondly, the targets can just react with probes and produce the amplified signal in one-pot. Finally, the targets can be simultaneously detected within 10min in different channels, thus high-throughput measurement can be achieved. Based on this work, it is estimated that this detection platform will be universally served as a simple, sensitive and portable platform for antibiotic contaminants detection in biological and environmental samples.

Factors predicting home storage of medicines in Northern Uganda

BACKGROUND

Medicines are kept in households Worldwide for first aid, treatment of chronic or acute disease conditions. This promotes inappropriate use of medicines and hence the associated risks. The study explored the factors which predict availability and utilization of medicines in households of Northern Uganda.

METHOD

A cross sectional survey of 892 households was performed from November-to-December 2012. Five data collectors administered the questionnaires, respondents were requested to bring out any medicines present in their households. Demographic characteristics, drug name, quantity, source, formulation, legibility of drug labels and reasons why the medicines were being kept at home was collected. Data was analyzed using STATA 12.0 at 95% level of significance.

RESULTS

Of the households visited, 35.1% (313/892) had drugs. Paracetamol (11.8%), coartem (11.3%), cotrimoxazole (10%), amoxicillin (9.2%) and metronidazole (8.2%) were the major medicines found. Antibacterial drugs were the most commonly (40.1%) kept type of drugs. The medicines present in households were for on-going treatment (48%); 'leftover' (30.5%) and anticipated future use (21.6%). Symptoms of malaria (34.1%) were common in households which had drugs. The medicines kept in homes were mainly from the private sector 60.5% (497/821). The rate of home drug storage was higher 85.3% (267/313) amongst the educated individuals. There was high prevalence 76% (238/313) of self-medication among respondents in households which stored drugs. The average number of medicines in each household was 6 ± 5 with majority (68.1%) having between 1-10 drugs. Previous successful treatment (OR: 1.3; 95% CI: 0.95-1.77), regular income (OR: 1.8; 95% CI: 1.2-2.6) and sex (OR: 0.63; 95% CI: 0.5-0.9) predicted storage of medicines in households in northern Uganda.

CONCLUSION

Over a third of households in Northern Uganda store medicines with antibacterial agents being the most common. Self-medication is common among individuals in households which keep drugs. Past successful treatment, regular income and sex predict community home drug storage.

Development of a new fluorescence immunochromatography strip for detection of chloramphenicol residues in chicken muscles

BACKGROUND

Chloramphenicol (CAP), an antimicrobial drug that is widely used in animal feed, would have a negative effect on human health due to its low elimination rate and relatively high residue in animal food. It is important to develop a rapid and economic method to determine CAP in animal food to ensure that human health is not affected.

RESULTS

A new fluorescence immunochromatography strip was developed and established for the detection of CAP residue in chicken muscles for the first time. A CAP-bovine serum albumin conjugate, monoclonal antibody and polyclonal antibody against CAP were applied to constitute a fluorescence immunochromatography strip. The fluorescence intensity was detected by a charge-coupled device scanner and transformed to a digital value. The CAP linearity working range was from 0.1 ng mL(-1) to 20 ng mL(-1) with a limit of detection of 0.1 ng mL(-1) within 10 min. The performance of the strip assay was compared with a commercial ELISA kit and the correlation coefficient was 0.99, which indicated that the new strip assay had a good quantification ability for CAP.

CONCLUSION

The fluorescence immunochromatography strip was successfully applied to the detection of CAP residues in chicken samples. To our knowledge, it is the first report regarding the development of a fluorescence immunochromatography method for screening CAP in animal samples.

Reaction or infection: topical chloramphenicol treatment

Chloramphenicol is a topical treatment that is used widely, especially in wounds around the eyes. In our practice there have been a number of cases of delayed hypersensitivity to chloramphenicol that has been mismanaged initially as an infective cellulitis. We hope to share some of our experience of this uncommon reaction to highlight the delayed reaction that can occur with topical application of this drug.

In vitro selection and characterization of DNA aptamers recognizing chloramphenicol

Chloramphenicol (Cam), although an effective antibiotic, has lost favour due to some fatal side effects. Thus there is an urgent need for rapid and sensitive methods to detect residues in food, feed and environment. We engineered DNA aptamers that recognize Cam as their target, by conducting in vitro selections. Aptamers are nucleic acid recognition elements that are highly specific and sensitive towards their targets and can be synthetically produced in an animal-friendly manner, making them ethical innovative alternatives to antibodies. None of the isolated aptamers in this study shared sequence homology or structural similarities with each other, indicating that specific Cam recognition could be achieved by various DNA sequences under the selection conditions used. Analyzing the binding affinities of the sequences, demonstrated that dissociation constants (K(d)) in the extremely low micromolar range, which were lower than those previously reported for Cam-specific RNA aptamers, were achieved. The two best aptamers had G rich (>35%) nucleotide regions, an attribute distinguishing them from the rest and apparently responsible for their high selectivity and affinity (K(d)∼0.8 and 1μM respectively). These aptamers open up possibilities to allow easy detection of Cam via aptamer-based biosensors.

Chloramphenicol causes mitochondrial stress, decreases ATP biosynthesis, induces matrix metalloproteinase-13 expression, and solid-tumor cell invasion

Overuse and abuse of antibiotics can increase the risk of cancer. Chloramphenicol can inhibit both bacterial and mitochondrial protein synthesis, causing mitochondrial stress and decreased ATP biosynthesis. Chloramphenicol can accelerate cancer progression; however, the underlying mechanisms of chloramphenicol in carcinogenesis and cancer progression are still unclear. We found that chloramphenicol can induce matrix metalloproteinase (MMP)-13 expression and increase MMP-13 protein in conditioned medium, resulting in an increase in cancer cell invasion. Chloramphenicol also activated c-Jun N-terminal kinases (JNK) and phosphatidylinositol 3-kinase (PI-3K)/Akt signaling, leading to c-Jun protein phosphorylation. The activated c-Jun protein has been proven to activate binding to the MMP-13 promoter and also upregulate the amount of MMP-13. Both the SP 600125 (JNK inhibitor) and LY 294002 (PI-3K/Akt inhibitor) can inhibit chloramphenicol-induced c-Jun phosphorylation, MMP-13 expression, and cell invasion. Overexpression of the dominant-negative JNK and PI-3K p85 subunit also negate chloramphenicol-induced responses. Other antibiotics that cause mitochondrial stress and a decrease in ATP biosynthesis also induce MMP-13 expression. These findings suggest that chloramphenicol-induced PI-3K/Akt, JNK phosphorylation, and activator protein 1 activation might function as a novel mitochondrial stress signal that result in an increase of MMP-13 expression and MMP-13-associated cancer cell invasion. The findings of this study confirms that chloramphenicol, and other 70S ribosomal inhibitors, should be administered with caution, especially during cancer therapy.

The inventory of antibiotics in Russian home medicine cabinets

The objective of this study was to inventory the stock of antimicrobials in the home medicine cabinets (HMCs) of the general population in Russia and to find out for which indications people report that they would use antibiotics without a physician's recommendation. The research was performed in 9 Russian cities by physicians who visited households. An inventory of antibiotics in HMCs was made, and respondents were asked about instances in which they would choose automedication with antibiotics. We found that 83.6% of families had antibiotics for systemic use in HMCs. The most common antibiotics in HMCs were trimethoprim-sulfamethoxazole (46.3% of HMCs), ampicillin (45.1%), chloramphenicol (32.7%), erythromycin (25.5%), and tetracycline (21.8%). The major indications for automedication with antibiotics were acute viral respiratory tract infections (12.3% of total indications), cough (11.8%), intestinal disorders (11.3%), fever (9%), and sore throat (6.8%). According to this study, antibiotics are widely stocked among the general population in Russia, and people use antibiotics in an uncontrolled and imprudent manner.