Combined effects of vancomycin and imipenem against methicillin-resistant Staphylococcus aureus (MRSA) in vitro and in vivo

Evaluation of the synergistic potential of vancomycin combined with other antimicrobial agents against methicillin-resistant Staphylococcus aureus and coagulase-negative Staphylococcus spp strains

“…The VAN + IMP combination was evaluated by E-test strips and synergistic effects were observed on almost all strains (95.5 %), except for strain 193, a MRCNS which showed an additive effect with a FIC index of 0.6, a value very close to the parameter set for synergistic effect (FIC ≤ 0.5) (Table II). This result is in agreement with studies by Totsuka et al (1999) and Kobayashi (2005), who showed synergism between VAN and IPM in 94% and 92% of the MRSA strains, respectively. In our study, MRSA strains with MIC ≥ 32 μg/mL for IPM when combined with 1/2 MIC of VAN became susceptible to IPM with MIC values ≤ 0.4 μg/mL (Table II).…”

“…In both trials, the combination of 1/2 MIC of VAN + 1/2 MIC of IPM was shown to be synergistic, with an average reduction of 5 log CFU/mL for all four selected strains in relation to VAN alone after 24 h of incubation. These results are in agreement with other studies which showed the bactericidal activity of this combination after 24 h of incubation with MRSA strains, using the time-kill curve method (Totsuka et al 1999, Rochon-Edouard et al 2000, Jacqueline et al 2005. There was no significant decrease in log CFU after antimicrobial reapplication, indicating a non-concentration-dependent activity previously described as a pharmacological propriety of β-lactam drugs (Brunton et al 2006).…”

“…Due to a lack of therapeutic options, some studies have focused on the combination of two or more antibiotics as an alternative treatment (Totsuka et al 1999, Rochon-Edouard et al 2000, Kobayashi 2005, Yamaoka 2007, Nguyen & Graber 2010. Promising results in vitro and in vivo could lead to effective therapy along with a reduction of therapeutic doses, adverse effects and treatment duration.…”

Antibiotics Against Endocarditis – Past, Present and Future (Experimental Data)

“…Penicillin-binding protein 2A (PBP2A) is the protein responsible for the methicillin resistance mechanism in S. aureus. Methicillin resistance confers resistance to all the beta-lactams, including cephalosporins and carbapenems; however, many studies have reported a potent efficacy of imipenem against S. aureus when used in combination with other antimicrobial agents, including fosfomycin (Nakazawa et al, 2003), vancomycin (Totsuka K et al, 1999;Benquan et al, 2002;Rochon-Edouard et al, 2000), and cephalosporins (Uete & Matsuo et al, 1995).…”

Vancomycin-Resistant MRSA Induced by β-Lactam Antibiotics in Mansoura University Hospitals, Egypt

“…The use of a combination of VA and ß-lactam antibiotics was one of the solutions for treating of such mixed infections depending on strong synergy (Totsuka et al, 1999).…”