Anti-S. aureus Monoclonal antibody, Clone C485M

A series of novel pleuromutilin derivatives possessing 1,2,3-triazole moieties were synthesized via click reactions under mild conditions. The in vitro antibacterial activities of these derivatives against 4 strains of S. aureus (MRSA ATCC 43300, ATCC 29213, AD 3, and 144) and 1 strain of E. coli (ATCC 25922) were tested by the broth dilution method. The majority of the synthesized derivatives displayed potent antibacterial activities against MRSA (MIC = 0.125-2 mu g/mL). It was also found that most compounds had no significant inhibitory effect on the proliferation of RAW264.7 cells at the concentration of 8 mu g/mL. Among these derivatives, compound 32 (similar to 1.71 log(10) CFU/g) containing dimethylamine group side chain displayed more effective than tiamulin (similar to 0.77 log(10) CFU/g) at the dose of 20 mg/kg in reducing MRSA load in thigh infected mice. Additionally, compound 32 (the survival rate was 50%) also displayed superior in vivo efficacy to that of tiamulin (the survival rate was 20%) in the mouse systemic model. Structure-activity relationship (SAR) studies resulted in compound 32 with the most potent in vitro and in vivo antibacterial activity among the series. Moreover, compound 32 was evaluated in CYP450 inhibition assay and showed moderate in vitro inhibition of CYP3A4 (IC50 = 6.148 mu M). (C) 2020 Elsevier Masson SAS. All rights reserved.

Staphylococcus aureusis an emergent etiology of community-acquired pneumonia (CAP) over the past 2 decades, with severe community-acquired pneumonia (SCAP) caused by methicillin-resistantS. aureus(MRSA) leading to critical illness and death.S. aureuscolonization is associated with a high incidence of pneumonia. Panton-Valentine leukocidin (PVL) is one of the most important virulence factors ofS. aureusassociated with serious complications. In recent years, community-associated MRSA (CA-MRSA) clones that caused infections in young adults and healthy individuals with no exposure to health care settings and no classical risk factors have emerged. Clinical features at admission including concurrent influenza infection, hemoptysis, multilobar infiltrates, and neutropenia should suggestS. aureusCAP. Sputum Gram stains, cultures (or tracheobronchial aspirates or bronchoalveolar lavage in mechanically ventilated patients), polymerase chain reaction (nasopharyngeal or oropharyngeal or lower respiratory tract specimens), and two sets of blood cultures should be obtained from patients presenting with severeS. aureusCAP. For CAP due to methicillin-susceptibleS. aureus, first-line therapy is usually cefazolin, oxacillin, or ceftaroline. For CA-MRSA pneumonia, linezolid is recommended. If vancomycin or teicoplanin are used, combination with clindamycin or rifampicin should be considered in cases of PVL-positive MRSA CAP.