A quadruple-channel fluorescent sensor array based on label-free carbon dots for sensitive detection of tetracyclines.

A quadruple-channel fluorescent sensor array based on label-free carbon dots (CDs) was fabricated to detect and discriminate a series of tetracyclines (TCs), including chlortetracycline (CTC), oxytetracycline (OTC), tetracycline (TC) and doxycycline (DOX). Blue-emitting carbon dots (B-CDs) and green-emitting carbon dots (G-CDs) were prepared to serve as four sensing elements. When the TCs were directly mixed with CDs, the fluorescence quenching phenomenon appeared. Since different TCs exhibited different affinities for sensing elements, the sensor array displays a distinct fluorescence pattern of the fluorescence intensity variation (F0 - F)/F0 for each of these TCs, which is further analyzed by principal component analysis (PCA). The present fluorescent sensor array has the capacity to differentiate TCs at a low concentration of 1 µM. Meanwhile, quantitative detection with a lower limit (0.30 µM) for TCs could be achieved by applying a single element. Moreover, a high accuracy (100%) examination of unknown samples is acquired. Finally, the fluorescent sensor array performs well in distinguishing binary mixtures and could also recognize TCs in milk.

Omadacycline: A New Tetracycline Antibiotic.

OBJECTIVE: To review the chemistry, pharmacology, microbiology, pharmacokinetics, pharmacodynamics, clinical efficacy, tolerability, dosage, and administration of omadacycline, a new tetracycline antibiotic. DATA SOURCES: A literature search through PubMed, Google Scholar, and clinicaltrials.gov was conducted (2008 to October 2018) using the search terms omadacycline and PTK-0796. Abstracts presented at recent conferences, prescribing information and information from the FDA and the manufacturer's website were reviewed. STUDY SELECTION AND DATA EXTRACTION: Preclinical data and published phase 1, 2, and 3 studies were evaluated. DATA SYNTHESIS: Omadacycline displays in vitro activity against a wide range of bacteria. Clinical trials have shown that omadacycline is noninferior to linezolid for the treatment of acute bacterial skin and skin structure infections (ABSSSI) and noninferior to moxifloxacin for the treatment of community-acquired bacterial pneumonia (CABP). A loading dose of 200 mg intravenously (IV) once or 100 mg IV twice or 450 mg orally once is recommended followed by a maintenance dose of 100 mg IV or 300 mg orally once daily. No dosage adjustment is needed in patients with renal or hepatic impairment. Omadacycline is well tolerated, with nausea being a common adverse effect, but is associated with food and drug interactions. Relevance to Patient Care and Clinical Practice: Omadacycline is active against staphylococci, including methicillin-resistant strains, and streptococci, including tetracycline-resistant strains, as well as atypical bacteria. Omadacycline provides clinicians with an additional parenteral and oral option for the treatment of adults with ABSSSI and CABP. CONCLUSION: Omadacycline is an alternative treatment option for ABSSSI and CABP.

Integrated 2-D CE.

A simple methodology for converting a commercial CE-MS instrument into an integrated 2-D CE system has been developed. The first-dimensional capillary operates as a typical CE instrument with UV/visible detection. Fractions leaving the first dimension are automatically collected and introduced into the second dimension, performed on a CE-MS apparatus, for analysis. The integrated system allows fractions in the second dimension to be analyzed using various electrophoretic modes. As an example, in this work we performed the separation of two families of antibiotics (nitroimidazoles and tetracyclines) in the first dimension and the subsequent resolution of the antibiotics in each family (nitroimidazoles were resolved by MEKC and tetracyclines by CZE) in the second dimension. The proposed system, which operates in an highly automatic manner, is flexible and allows various combination of electrophoretic modes to be implemented. In addition, the use of a mass spectrometer detector in the second dimension further increases the analytical potential of the system as a result of the high selectivity and wealth of structural information provided by the MS detector.

Ehrlichiosis in children.

Ehrlichia are obligate intracellular bacteria that belong to the family Rickettsiaceae. Human monocytic ehrlichiosis (HME) and human granulocytic ehrlichiosis (HGE) are the 2 ehrlichial diseases that are of greatest health concern in the United States. The agents causing HME and HGE are zoonotic pathogens requiring a mammalian reservoir and an arthropod vector. Differences in the geographic distribution of their tick vectors account for the concentration of HME in the South and southeastern United States and HGE in the Northeast and northern Midwest. Both infections have been reported in coastal regions from Rhode Island to Florida. HME and HGE are flulike illnesses that usually are self-limited but may be fatal. Diagnosis is confirmed by identification of the microorganism on blood smear or polymerase chain reaction or by detection of anti-ehrlichial antibody. Doxycycline is the antibiotic of choice for treatment of ehrlichiosis.

New developments in tetracycline antibiotics: glycylcyclines and tetracycline efflux pump inhibitors.

The tetracyclines, discovered in the 1940s, are a well-established class of antibiotics that still have a role in treating microbial infections in man. However, the widespread emergence of bacterial resistance due to efflux and ribosomal protection mechanisms has severely limited their effectiveness. A new generation of tetracyclines, the glycylcyclines, has been developed to overcome resistance to earlier tetracyclines. One of the new glycylcyclines, 9-t-butylglyclamido-minocycline (GAR-936, tigecycline) is currently undergoing clinical trials. This review considers the current status of glycylcyclines and the possibility that resistance to these agents might arise in the future. Other approaches are also being taken to address the emergence of resistance to tetracyclines. Recently, a number of tetracycline efflux pump inhibitors have been discovered that might be used in combination with earlier tetracyclines to restore their activity against resistant organisms. However, the development of tetracycline efflux pump inhibitors is complicated by the occurrence of several efflux pump sub-families and by the presence of both efflux and ribosomal protection mechanisms in the same organism, especially in naturally occurring, Gram-positive clinical isolates.

Tet determinants provide poor protection against some tetracyclines: further evidence for division of tetracyclines into two classes.

Atypical tetracyclines were active against Escherichia coli and Staphylococcus aureus strains containing determinants that mediate resistance to typical tetracyclines by efflux (Tet B and Tet K) or ribosomal protection (Tet M) mechanisms. The results support recently published data that tetracyclines are divisible into at least two classes on the basis of their modes of action.