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Chen H, Li L, Liu Y, Wu M, Xu S, Zhang G, Qi C, Du Y, Wang M, Li J, Huang X. In vitro activity and post-antibiotic effects of linezolid in combination with fosfomycin against clinical isolates of Staphylococcus aureus. Infect Drug Resist 2018; 11:2107-2115. [PMID: 30464553 PMCID: PMC6219420 DOI: 10.2147/idr.s175978] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Objectives Linezolid combination therapy is recommended for the treatment of Staphylococcus aureus (S. aureus) infections. However, the optimal regimen of the combination therapy for S. aureus is unknown. The objective of this study was to investigate the antibacterial activity, post-antibiotic effect (PAE), and post-antibiotic subminimum inhibitory concentration (MIC) effect (PA-SME) of linezolid alone and in combination with fosfomycin against eleven clinical isolates of S. aureus. Methods The synergistic effects and antibacterial activity of linezolid and fosfomycin were assessed by checkerboard and time-kill assays. To determine the PAE and PA-SME, S. aureus strains in the logarithmic phase of growth were exposed for 1, 2, and 3 hours to the antibiotics, alone and in combination. Recovery periods of test strains were evaluated using viable counting after dilution. Results Synergistic effects were observed for eight strains and no antagonism was found with any combination. Moreover, linezolid combined with fosfomycin at 4x MIC showed the best synergistic antibacterial effect, and this effect was retained after 24 hours. In addition, both the antibiotics alone and in combination showed increased PAE and PA-SME values in a concentration- and time-dependent manner. Conclusion Linezolid combined with fosfomycin exerted a good antibacterial effect against S. aureus, and the combinations have significant PAE and PA-SME.
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Affiliation(s)
- Hao Chen
- Department of Pharmacy, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China.,Department of Basic and Clinical Pharmacology, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China, .,Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China,
| | - Lan Li
- Department of Basic and Clinical Pharmacology, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China, .,Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China,
| | - Yanyan Liu
- Department of Infectious Diseases, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China,
| | - Maomao Wu
- Department of Basic and Clinical Pharmacology, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China, .,Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China,
| | - Shuangli Xu
- Department of Basic and Clinical Pharmacology, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China, .,Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China,
| | - Guijun Zhang
- Department of Basic and Clinical Pharmacology, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China, .,Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China,
| | - Caifen Qi
- Department of Basic and Clinical Pharmacology, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China, .,Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China,
| | - Yan Du
- Department of Basic and Clinical Pharmacology, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China, .,Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China,
| | - Mingli Wang
- Department of Microbiology, Anhui Medical University, Hefei, Anhui, China
| | - Jiabin Li
- Department of Infectious Diseases, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China,
| | - Xiaohui Huang
- Department of Basic and Clinical Pharmacology, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China, .,Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, Anhui, China,
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Zhou YF, Yu Y, Sun J, Tao MT, Zhou WJ, Li X, Liao XP, Liu YH. Ex vivo pharmacokinetic/pharmacodynamic relationship of valnemulin against Clostridium perfringens in plasma, the small intestinal and caecal contents of rabbits. Anaerobe 2016; 39:150-7. [PMID: 27060276 DOI: 10.1016/j.anaerobe.2016.04.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 02/23/2016] [Accepted: 04/05/2016] [Indexed: 12/17/2022]
Abstract
The pharmacokinetic (PK) and ex vivo pharmacodynamic (PD) of valnemulin against Clostridium perfringens were investigated in plasma, the small intestinal and caecal contents of rabbits following intravenous (IV) or oral administration at 3 mg/kg bodyweight (BW). The postantibiotic effect (PAE) and postantibiotic sub-MIC effect (PA-SME) of valnemulin against C. perfringens ATCC13124 were also determined. The time-kill curves were established in vitro and ex vivo to evaluate the antibacterial activity of valnemulin against C. perfringens. The elimination half-lives (T1/2λz) of valnemulin in the jejunal fluids (7.82 h) or caecal contents (14.8 h) of rabbits was significantly longer than that in plasma (2.94 h). The MIC values of valnemulin against C. perfringens ATCC13124 were both 0.063 μg/mL in the artificial medium and jejunal fluids. The PAEs of valnemulin against C. perfringens were 2.9 h (1 × MIC) and 5.03 h (4 × MIC), and the PA-SMEs ranged from 7.9 h to 11.1 h. Valnemulin exhibited rapid, time-dependent killing feature, and the ex vivo dose-response profile was closely fitted to sigmoid Emax model (r(2) = 0.9985). The surrogate index of AUC24 h/MIC ratios required to achieve the bactericidal and virtual bacterial elimination effects were 57.5 and 90.1 h, respectively. Accordingly, the calculated daily dosage regimens of valnemulin for the bactericidal activity (1.96 mg/kg) and bacterial elimination (3.08 mg/kg) would be therapeutically effective in rabbits against C. perfringens with MIC ≤0.5 μg/mL.
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Affiliation(s)
- Yu-Feng Zhou
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China; Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China
| | - Yang Yu
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China; Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China
| | - Jian Sun
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China; Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China
| | - Meng-Ting Tao
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China; Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China
| | - Wen-Jie Zhou
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China; Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China
| | - Xiao Li
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China; Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China
| | - Xiao-Ping Liao
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China; Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China
| | - Ya-Hong Liu
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China; Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China; Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu, China.
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Abstract
In the past 20 years, an increased discrepancy between new available antibacterials and the emergence of multidrug-resistant strains has been observed. This condition concerns physicians involved in the treatment of central nervous system (CNS) infections, for which clinical and microbiological success depends on the rapid achievement of bactericidal concentrations. In order to accomplish this aim, the choice of drugs is based on their disposition toward the cerebrospinal fluid (CSF), which is influenced by the physicochemical characteristics of antibacterials. A reduced distribution into CSF has been documented for beta-lactams, especially cephalosporins and carbapenems, on the basis of their hydrophilic nature. However, they represent a cornerstone of the majority of combined therapeutic schemes for their ability to achieve bactericidal concentrations, especially in the presence of inflamed meninges. The good tolerability of beta-lactams makes possible high daily dose intensities, which may be associated with increased probability of cure. Furthermore, the adoption of continuous infusion seems to be a fruitful option. Fluoroquinolones, namely moxifloxacin, and antituberculosis drugs, together with the agents such as linezolid, reach the highest CSF/plasma concentration ratio, which is greater than 0.8, and for most of these drugs it is near 1. For all drugs that are currently used for the treatment of CNS infections, the evaluation of pharmacokinetic/pharmacodynamic parameters, on the basis of dosing regimens and their time-dependent or concentration-dependent pattern of bacterial killing, remains an important aspect of clinical investigation and medical practice.
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Affiliation(s)
- Antonello Di Paolo
- Division of Pharmacology, Department of Clinical and Experimental Medicine, University of Pisa, Via Roma 55, 56126, Pisa, Italy
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Zhao DH, Yu Y, Zhou YF, Shi W, Deng H, Liu YH. Postantibiotic effect and postantibiotic sub-minimum inhibitory concentration effect of valnemulin against Staphylococcus aureus isolates from swine and chickens. Lett Appl Microbiol 2013; 58:150-5. [PMID: 24117872 DOI: 10.1111/lam.12168] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 09/23/2013] [Accepted: 09/23/2013] [Indexed: 11/30/2022]
Abstract
UNLABELLED The postantibiotic effect (PAE) and postantibiotic sub-minimum inhibitory concentration (MIC) effect (PA-SME) of valnemulin against Staphylococcus aureus were investigated in vitro using a spectrophotometric technique and classic viable count method. A standard curve was constructed by regression analysis of the number of colonies and the corresponding optical density (OD) at 630 nm of the inoculum. After exposure to valnemulin at different concentrations for an hour, the antibiotic was removed by centrifuging and washing. The PA-SMEs were measured after initial exposure to valnemulin at 4 × the MIC, and then, valnemulin was added to reach corresponding desired concentrations in the resuspended culture. Samples were collected hourly until the culture became turbid. The results were calculated by converting the OD values into the counts of bacteria in accordance with the curve. The MIC of valnemulin against eight strains was identically 0.125 μg ml(-1) . The mean PAEs were 2.12 h (1 × MIC) and 5.06 h (4 × MIC), and the mean PA-SMEs were 6.85 h (0.1 × MIC), 9.12 h (0.2 × MIC) and 10.8 h (0.3 × MIC). The results showed that the strains with identical MICs exhibited different PAEs and PA-SMEs. Valnemulin produced prolonged PAE and PA-SME periods for Staph. aureus, supporting a longer dosing interval while formulating a daily administration dosage. SIGNIFICANCE AND IMPACT OF THE STUDY In this study, valnemulin demonstrated prolonged postantibiotic effects and postantibiotic sub-MIC effects on strains of Staphylococcus aureus. The strains with identical MICs of valnemulin exhibited different PAEs and PA-SMEs. Staphylococcus aureus isolated from different species has little impact on the postantibiotic effect of valnemulin. The result suggests a longer dosing interval while formulating a daily administration dosage, and it may play a valuable role of valnemulin in treating Staph. aureus infections in animals.
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Affiliation(s)
- D H Zhao
- National Reference Laboratory of Veterinary Drug Residues (SCAU), College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
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Sauermann R, Schwameis R, Fille M, Ligios MLC, Zeitlinger M. Antimicrobial activity of cefepime and rifampicin in cerebrospinal fluid in vitro. J Antimicrob Chemother 2008; 62:1057-60. [PMID: 18658192 DOI: 10.1093/jac/dkn312] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES Though used for infections of the central nervous system, the pharmacodynamics of antimicrobial agents is commonly evaluated only in commercially available bacterial growth media. In the present study, the effects of cerebrospinal fluid (CSF) on bacterial killing by cefepime and rifampicin were investigated. METHODS CSF was collected from patients who did not receive antibiotics. Time-kill curves were performed over 24 h using drug concentrations of 0.25-, 0.5-, 1-, 2-, 4- and 8-fold the respective MIC for the Staphylococcus aureus test strain. Killing curves were performed in Mueller-Hinton broth (MHB), in CSF incubated in ambient air (CSF(AIR)) and in CSF in air with 5% CO(2) (CSF(CO(2))). CO(2) served to adjust the pH of CSF to physiological values. RESULTS Sustained bacterial killing was achieved by cefepime at lower drug concentrations in CSF(CO(2)) than in MHB. In contrast, rifampicin concentrations above the MIC were required to exert sustained killing in CSF(CO(2)). Both drugs were least effective in CSF(AIR). CONCLUSIONS Standard susceptibility tests may lead to over- or underestimation of the activity of distinct antibiotics in CSF. Evaluation of the antimicrobial activity in pH-adjusted CSF can provide useful information on drugs considered for the treatment of bacterial infections residing in CSF.
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Affiliation(s)
- Robert Sauermann
- Division of Molecular Pharmacokinetics and Imaging, Department of Clinical Pharmacology, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria.
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Abstract
The continuous increase of resistant pathogens causing meningitis has limited the efficacy of standard therapeutic regimens. Due to their excellent activity in vitro and their good penetration into the cerebrospinal fluid (CSF), fluoroquinolones appear promising for the treatment of meningitis caused by gram-negative microorganisms, ie, Neisseria meningitidis and nosocomial gram-negative bacilli. The newer fluoroquinolones (moxifloxacin, gemifloxacin, gatifloxacin, and garenoxacin) have excellent activity against gram-positive microorganisms. Studies in animal models and limited clinical data indicate that they may play a future role in the treatment of pneumococcal meningitis. Analysis of pharmacodynamic parameters suggests that CSF concentrations that produce a C(peak)/minimal bactericidal concentration (MBC) ratio of at least 5 and concentrations above the MBC during the entire dosing interval are a prerequisite for maximal bactericidal activity in meningitis. Of interest, newer fluoroquinolones act synergistically with vancomycin and beta-lactam antibiotics (ceftriaxone, cefotaxime, meropenem) against penicillin-resistant pneumococci in experimental rabbit meningitis, potentially providing a new therapeutic strategy. Clinical trials are needed to further explore the usefulness of quinolones as single agents or in combination with other drugs in the therapy of pneumococcal meningitis.
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Affiliation(s)
- Philippe Cottagnoud
- *Department of Internal Medicine, Inselspital, Freiburgstrasse, 3010 Bern, Switzerland.
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