Breaking boundaries: the advancements in transdermal delivery of antibiotics

Transdermal drug delivery systems (TDDS) for antibiotics have seen significant advances in recent years that aimed to improve the efficacy and safety of these drugs. TDDS offer many advantages over other conventional delivery systems such as non-invasiveness, controlled-release pattern, avoidance of first-pass metabolism. The objective of this review is to provide an overview on the recent advances in the TDDS of different groups of antibiotics including β-lactams, tetracyclines, macrolides, and lincosamides, utilized for their effective delivery through the skin and to explore the challenges associated with this field. The majority of antibiotics do not have favorable properties for passive transdermal delivery. Thus, novel strategies have been employed to improve the delivery of antibiotics through the skin, such as the use of nanotechnology (nanoparticles, solid-lipid nanoparticles, nanoemulsions, vesicular carriers, and liposomes) or the physical enhancement techniques like microneedles and ultrasound. In conclusion, the transdermal delivery systems could be a promising method for delivering antibiotics that have the potential to improve patient outcomes and enhance the efficacy of drugs. Further research and development are still needed to explore the potential of delivering more antibiotic drugs by using various transdermal drug delivery approaches.

Cross-reactivity among and between macrolides, lincosamides, and streptogramins: Study on the French pharmacovigilance database

BACKGROUND

Hypersensitivity reactions (HSR) are reported for the macrolides, lincosamides, and streptogramins (MLS) antibiotic family. Data about cross-reactivity among and between MLS remain scarce or controversial.

OBJECTIVES

The aim of this study was to provide an overview of hypersensitivity cross-reactions among MLSs based on data extracted from the French National Pharmacovigilance Database (FPVD).

METHODS

Cases of HSR to MLSs reported between January 1985 and December 2019 were extracted from the FPVD using standardized MedDRA queries (SMQ). Cases including an allergological test involving multiple MLSs and giving at least one positive result were included.

RESULTS

Of the 8394 cases reviewed, 149 were included. HSR mainly involved pristinamycin (n = 83; 53.2%) and spiramycin (n = 31; 19.9%). HSR to MLS was immediate in 54 cases and delayed in 94 cases. Skin tests represented the majority of the allergological tests performed (n = 728; 84.7%), followed by reintroduction tests (n = 79; 9.2%). Eighty-six cross-reactivities among MLS were identified in 62 cases (41.6%). All the 25 explorations performed for streptogramins showed cross-reactivities, but only 30/253 among macrolides (11.9%). Cross-reactivities between the three MLS were observed in 31/322 (9.6%) of the allergological explorations.

CONCLUSION

This study highlights the possibility of cross-reactivity among and between MLSs. Dermatologists and allergologists managing patients with HSR to MLSs should be aware of a risk of cross-reactivity among the macrolides and between the different classes of MLS and to perform MLSs allergological testing before recommending an alternative antibiotic, especially in severe drug hypersensitivity from the MLS family.

Validation and application of an immunochromatographic test to detect four macrolides and two lincosamides in raw cow milk

In this study, an immunochromatographic test (using the Charm QUAD2® Test) was used to screen for residual macrolides and lincosamides in raw cow's milk. The validation parameters (selectivity/specificity, detection capability (CCβ), and ruggedness) were in agreement with the requirements of[EC] 2021. The selectivity of the immunochromatographic test was verified by the negative results of microbiological tests. The false-positive rate was 0%. The CCβ values of the immunochromatographic test for various antibiotics in milk were as follows: erythromycin 0.02 mg/kg, spiramycin 0.1 mg/kg, tilmicosin 0.025 mg/kg, tylosin 0.05 mg/kg, lincomycin 0.15 mg/kg, and pirlimycin 0.15 mg/kg. The determined CCβ values were lower than the respective maximum residue limits (MRLs; regulatory limits in Japan) for milk, except for lincomycin (equal to the MRL). The presence of antibiotic groups other than macrolides and lincosamides did not interfere with the specificity of the test. It showed no significant difference in lot-to-lot repeatability. The results obtained by the two researchers showed no significant differences. Finally, the test was applied to milk samples obtained from a tylosin-treated cow. The outcome was positive and in agreement with the results of the chemical analytical and microbiological methods. Therefore, this validated immunochromatographic test is expected to be suitable for routine analysis to ensure milk safety.

Efficacy and Safety of Intravenous Lincosamide Therapy in Methicillin-Resistant Staphylococcus aureus Bacteremia

Methicillin-resistant Staphylococcus aureus (MRSA) bacteremia has a high case-fatality rate, but currently recommended antimicrobial therapies have many shortcomings. The efficacy and safety of lincosamide therapy for MRSA bacteremia is incompletely defined. A retrospective audit was done of the management of all adults with MRSA bacteremia at an Australian tertiary referral hospital between 1 January 2007 and 31 December 2020. A total of 176 patients were included. The case-fatality rate declined from 14/57 (25%) in the first half of the study to 12/119 (10%) in the second half (P = 0.01). Of the 172 patients receiving antibiotics, 62 (36%) received a lincosamide-predominant regimen (lincosamide monotherapy for >50% of the intravenous course). The patients receiving lincosamide-predominant intravenous therapy had lower in-hospital mortality (odds ratio [OR], 0.07; 95% confidence interval [CI], 0.01 to 0.53; P = 0.01) and a lower incidence of renal complications (OR [95% CI], 0.34 [0.15-0.75]; P = 0.008) than patients receiving an alternative regimen. In multivariate analysis that also considered age, disease severity, comorbidity, infectious diseases consultation, source control, and the year of admission, patients receiving a lincosamide-predominant regimen were still less likely to die in the hospital than those receiving an alternative regimen (OR [95% CI], 0.05 [0.00 to 0.65]; P = 0.02). Lincosamides appear to have utility, at least as stepdown therapy, in the treatment of MRSA bacteremia, particularly in young, clinically stable patients with few comorbidities in whom endocarditis has been excluded. Prospective studies will help define their optimal role.

Based on a 3 Year Procurement Records, 2015-2017

In this study, we investigated the trends and patterns of antibiotic consumption (macrolides and lincosamides) in China’s healthcare institutions from 2015 to 2017. The China Drug Supply Information Platform (CDSIP) was officially launched in 2015. We collected records from this national centralized bidding procurement system between 2015 and 2017. The use of J01F antibiotics (macrolides or lincosamides) was calculated in a defined daily dose per 1000 inhabitants per day (DID).Purchase data from 70,366 national medical facilities included in the CDSIP were collected. The procurement data of 66,007 medical facilities have not changed over 3 years. There is a slight decline in the consumption of J01F antibiotics, which decreased from 3.03 DID in 2015 to 2.91 DID in 2017. Azithromycin (20.6%) was the most commonly used antibiotic in 2017 among all classes, followed by clindamycin (17.9%) and erythromycin (13.7%). Parenteral antibiotics accounted for 32.0% of total antibiotic consumption and 59.6% of total antibiotics expenditure in 2017. The overall consumption of most antibiotics decreased slightly over the 3-yearstudy period. This may be owing to China’s health-related policies in the past few years. A gap still exists in antibiotic use between regions and dosage forms. Further studies are needed to optimize antibiotic prescribing and reduce antibiotic resistance.

Ribosome-Mediated Attenuation of vga(A) Expression Is Shaped by the Antibiotic Resistance Specificity of Vga(A) Protein Variants

Vga(A) protein variants confer different levels of resistance to lincosamides, streptogramin A, and pleuromutilins (LS_AP) by displacing antibiotics from the ribosome. Here, we show that expression of vga(A) variants from Staphylococcus haemolyticus is regulated by cis-regulatory RNA in response to the LS_AP antibiotics by the mechanism of ribosome-mediated attenuation. The specificity of induction depends on Vga(A)-mediated resistance rather than on the sequence of the riboregulator. Fine tuning between Vga(A) activity and its expression in response to the antibiotics may contribute to the selection of more potent Vga(A) variants because newly acquired mutation can be immediately phenotypically manifested.

Ribosome protection by ABC-F proteins-Molecular mechanism and potential drug design

Members of the ATP-binding cassette F (ABC-F) proteins confer resistance to several classes of clinically important antibiotics through ribosome protection. Recent structures of two ABC-F proteins, Pseudomonas aeruginosa MsrE and Bacillus subtilis VmlR bound to ribosome have shed light onto the ribosome protection mechanism whereby drug resistance is mediated by the antibiotic resistance domain (ARD) connecting the two ATP binding domains. ARD of the E site bound MsrE and VmlR extends toward the drug binding region within the peptidyl transferase center (PTC) and leads to conformational changes in the P site tRNA acceptor stem, the PTC, and the drug binding site causing the release of corresponding drugs. The structural similarities and differences of the MsrE and VmlR structures likely highlight an universal ribosome protection mechanism employed by antibiotic resistance (ARE) ABC-F proteins. The variable ARD domains enable this family of proteins to adapt the protection mechanism for several classes of ribosome-targeting drugs. ARE ABC-F genes have been found in numerous pathogen genomes and multi-drug resistance conferring plasmids. Collectively they mediate resistance to a broader range of antimicrobial agents than any other group of resistance proteins and play a major role in clinically significant drug resistance in pathogenic bacteria. Here, we review the recent structural and biochemical findings on these emerging resistance proteins, offering an update of the molecular basis and implications for overcoming ABC-F conferred drug resistance.

In Vitro Susceptibility of Clinical Staphylococcus aureus Small-Colony Variants to β-Lactam and Non-β-Lactam Antibiotics

The Staphylococcus aureus small-colony variant (SCV) phenotype has been associated with relapsing and antibiotic-refractory infections. However, little is known about the activities of antibiotics on clinical SCVs. Here, we demonstrated that SCVs without detectable auxotrophies were at least as susceptible to most β-lactam and non-β-lactam antibiotics in vitro as their corresponding clonally identical strains with a normal phenotype. After prolonged incubation, a regrowth phenomenon has been observed in gradient diffusion inhibition zones irrespective of the strains' phenotype.

Characterization of Enzymes Catalyzing Transformations of Cysteine S-Conjugated Intermediates in the Lincosamide Biosynthetic Pathway

Lincosamides such as lincomycin A, celesticetin, and Bu-2545, constitute an important group of antibiotics. These natural products are characterized by a thiooctose linked to a l-proline residue, but they differ with regards to modifications of the thioacetal moiety, the pyrrolidine ring, and the octose core. Here we report that the pyridoxal 5'-phosphate-dependent enzyme CcbF (celesticetin biosynthetic pathway) is a decarboxylating deaminase that converts a cysteine S-conjugated intermediate into an aldehyde. In contrast, the homologous enzyme LmbF (lincomycin biosynthetic pathway) catalyzes C-S bond cleavage of the same intermediate to afford a thioglycoside. We show that Ccb4 and LmbG (downstream methyltransferases) convert the aldehyde and thiol intermediates into a variety of methylated lincosamide compounds including Bu-2545. The substrates used in these studies are the β-anomers of the natural substrates. The findings not only provide insight into how the biosynthetic pathway of lincosamide antibiotics can bifurcate to generate different lincosamides, but also reveal the promiscuity of the enzymes involved.

Quantum mechanical studies of lincosamides

Lincosamides are a class of antibiotics used both in clinical and veterinary practice for a wide range of pathogens. This group of drugs inhibits the activity of the bacterial ribosome by binding to the 23S RNA of the large ribosomal subunit and blocking protein synthesis. Currently, three X-ray structures of the ribosome in complex with clindamycin are available in the Protein Data Bank, which reveal that there are two distinct conformations of the pyrrolidinyl propyl group of the bound clindamycin. In this work, we used quantum mechanical methods to investigate the probable conformations of clindamycin in order to explain the two binding modes in the ribosomal 23S RNA. We studied three lincosamide antibiotics: clindamycin, lincomycin, and pirlimycin at the B3LYP level with the 6-31G** basis set. The focus of our work was to connect the conformational landscape and electron densities of the two clindamycin conformers found experimentally with their physicochemical properties. For both functional conformers, we applied natural bond orbital (NBO) analysis and the atoms in molecules (AIM) theory, and calculated the NMR parameters. Based on the results obtained, we were able to show that the structure with the intramolecular hydrogen bond C=O…H-O is the most stable conformer of clindamycin. The charge transfer between the pyrrolidine-derivative ring and the six-atom sugar (methylthiolincosamide), which are linked via an amide bond, was found to be the dominant factor influencing the high stability of this conformer.