Background Antibiotics have been used for decades against Cutibacterium acnes (previously known as Propionibacterium acnes; C. acnes). Alarmingly, antibiotic resistance to this bacterium has become a worldwide problem in recent years. No studies are available on the antibiotic susceptibility patterns of C. acnes among Jordanian acne patients and how that is influenced by antibiotic use. This study aims to assess antibiotic resistance patterns of C. acnes clinical isolates and neighboring Gram-positive normal flora of the skin obtained from acne patients attending dermatology clinics in Amman –Jordan appraising the role of antibiotic consumption. Methods This is a cross-sectional study of acne patients presenting to selected dermatology outpatient clinics over a 6-month study period. Swabs obtained from inflamed lesions were cultured aerobically and anaerobically. Isolates were identified and screened for antibiotic susceptibility. In addition, all patients were asked to fill in a questionnaire that included questions about the history of antibiotic treatment. Results C. acnes was isolated from lesions of 100 patients out of 115 participants included in this study. 73% of the isolates were resistant to erythromycin and 59% to clindamycin 37% to doxycycline, 36% to tetracycline, 31% to trimethoprim / sulfamethoxazole, 15% to levofloxacin, and 3% to minocycline. Multi drug resistance (MDR) in C. acnes isolates as well as Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis) with a similar pattern of resistance were detected from the same patient in most cases. A pattern of higher resistance towards variable antibiotic was observed in patients previously treated with antibiotics for acne management. Conclusions The findings of this study demonstrate the distribution of antibiotic resistance of C. acnes towards used antibiotics and emphasizes the influence of antibiotic consumption on development of antibiotic resistance. The similar pattern of resistance between skin bacteria tested in this study highlights the genetic transfer of resistance between skin commensals including S. aureus and S. epidermidis hence promoting its circulation in the community.

Trialkylphosphines tris(2-carboxy-ethyl)-phosphine and tris(3-hydroxypropyl)-phosphine are popular reagents for the reduction of cysteine residues in bioconjugation reactions using maleimides. However, it has been demonstrated that these phosphines are reactive toward maleimide, necessitating their removal before the addition of the Michael acceptor. Here, a method using water-soluble PEG-azides is reported for the quenching of trialkylphosphines in situ, which is demonstrated to improve the level of maleimide conjugation to proteins.

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Cleavage of C3 to C3a and C3b plays a central role in the generation of complement-mediated defences. Although the thioester-mediated surface deposition of C3b has been well-studied, fluid phase dimers of C3 fragments remain largely unexplored. Here we show C3 cleavage results in the spontaneous formation of C3b dimers and present the first X-ray crystal structure of a disulphide-linked human C3d dimer. Binding studies reveal these dimers are capable of crosslinking complement receptor 2 and preliminary cell-based analyses suggest they could modulate B cell activation to influence tolerogenic pathways. Altogether, insights into the physiologically-relevant functions of C3d(g) dimers gained from our findings will pave the way to enhancing our understanding surrounding the importance of complement in the fluid phase and could inform the design of novel therapies for immune system disorders in the future.

Development of novel derivatives to rein in and fight bacteria have never been more demanding, as microbial resistance strains are alarmingly increasing. A multitude of new fluoroquinolones derivatives with an improved spectrum of activity and/or enhanced pharmacokinetics parameters have been widely explored. Reporting novel antimicrobial agents entails comparing their potential activity to their parent drugs; hence, parent fluoroquinolones have been used in research as positive controls. Given that these fluoroquinolones possess variable activities according to their generation, it is necessary to include parent compounds and market available antibiotics of the same class when investigating antimicrobial activity. Herein, we provide a detailed guide on the in vitro biological activity of fluoroquinolones based on experimental results published in the last years. This work permits researchers to compare and analyze potential fluoroquinolones as positive control agents and to evaluate changes occurring in their activities. More importantly, the selection of fluoroquinolones as positive controls by medicinal chemists when investigating novel FQs analogs must be correlated to the laboratory pathogen inquest for reliable results.