Background: Intubated patients are particularly at risk of developing infections caused by these pathogens, specifically, P. aeruginosa and A. baumannii. In the past fifteen years, Carbapenems were known to be the dru...Background: Intubated patients are particularly at risk of developing infections caused by these pathogens, specifically, P. aeruginosa and A. baumannii. In the past fifteen years, Carbapenems were known to be the drugs of choice for these bacteria. With the increase in the use and misuse of antibiotics, these bacteria became highly resistant, and almost all available antibiotics, including Carbapenems, became inefficient. Synergistic combination therapy may be a useful strategy in slowing as well as overcoming the emergence of resistance. The aim of this study was to evaluate the anti-bacterial activity on P. aeruginosa and A. baumannii of the combination of two antibiotics: Colistin and a Carbapenem (Meropenem or Imipenem). Methods: The antibacterial activity was assessed by determining the MIC. Then, the effect of combining the antibiotics was studied using the Checkerboard Technique described by White et al., 1996. The Fractional Inhibitory Concentration (FIC) for each strain was then calculated and classified as synergy, additive, indifference or antagonism. 11 strains of A. baumannii and 11 strains of P. aeruginosa were tested in the presence of Meropenem combined with Colistin or Imipenem combined with Colistin. Results: For the combination of Meropenem and Colistin, 6 strains of A. baumannii and 3 strains of P. aeruginosa showed synergy while 5 strains of A. baumannii and 7 strains of P. aeruginosa showed additive effect, only 1 strain of P. aeruginosa showed antagonism. For Imipenem and Colistin, only 1 strain of A. baumannii and 3 strains of Pseudomonas showed synergy while 8 strains of Acinetobacter and 8 strains of Pseudomonas showed additive effect. Conclusion: The “in vitro” combination Colistin-Carbapenem is associated with an improvement in MIC. In the majority of the cases, this improvement suggests a synergistic combination or an additive effect.展开更多
The relationship between antibiotic consumption and resistance has been widely evaluated. Pseudomonas aeruginosa is one of the most important opportunistic pathogens in the nosocomial setting, and its resistance to an...The relationship between antibiotic consumption and resistance has been widely evaluated. Pseudomonas aeruginosa is one of the most important opportunistic pathogens in the nosocomial setting, and its resistance to antibiotics is increaseing. Production of metallo-β-lactamases (MBLs) is currently the most fearful resistance mechanism due to the potential of dissemination. This study aimed to evaluate the correlation between antibiotic consumption (expressed in DDD/100 bed days) and resistance (expressed in % of isolates and patients) in different time periods for P. aeruginosa between 2006 and 2009 at Saint George Hospital University Medical Center (SGH-UMC), Beirut. Pearson correlation coefficients (r) were calculated and linear regression was performed. Detection of MBL-producing Imipenem resistant P. aeruginosa (IRPA) isolates between 2008 and 2009 was performed using three MBL screening methods: MBL Etest?, Imipenem/EDTA combined disk test and EDTA disk potentiation with four cephalosporins. The modified Hodge test was also performed. From 2006 till 2009, there was a trend of increasing resistance of P. aeruginosa to all antibiotics, and the highest % of resistance was for Ofloxacin. Concerning resistance expressed by isolates, high correlation coefficients resulted among Imipenem, Ciprofloxacin and Tazobactam consumption and resistance to these agents in the same year correlation;Ceftazidime and Ofloxacin consumption and resistance in the next year correlation;Gentamicin and Ofloxacin consumption and the change in resistance (ΔR). Concerning resistance expressed by patients, results were similar except for Ceftazidime and Ofloxacin correlation in the next year correlation. In MBL screening, three isolates gave accordance among 4 methods which showed a positive result. The correlation between antibiotic consumption and resistance is highly dependent on the kind of antibiotic, the organism and the time of correlation. Various MBL screening phenotypic methods on one isolate can increase accuracy and eliminate false positive and negative results.展开更多
文摘Background: Intubated patients are particularly at risk of developing infections caused by these pathogens, specifically, P. aeruginosa and A. baumannii. In the past fifteen years, Carbapenems were known to be the drugs of choice for these bacteria. With the increase in the use and misuse of antibiotics, these bacteria became highly resistant, and almost all available antibiotics, including Carbapenems, became inefficient. Synergistic combination therapy may be a useful strategy in slowing as well as overcoming the emergence of resistance. The aim of this study was to evaluate the anti-bacterial activity on P. aeruginosa and A. baumannii of the combination of two antibiotics: Colistin and a Carbapenem (Meropenem or Imipenem). Methods: The antibacterial activity was assessed by determining the MIC. Then, the effect of combining the antibiotics was studied using the Checkerboard Technique described by White et al., 1996. The Fractional Inhibitory Concentration (FIC) for each strain was then calculated and classified as synergy, additive, indifference or antagonism. 11 strains of A. baumannii and 11 strains of P. aeruginosa were tested in the presence of Meropenem combined with Colistin or Imipenem combined with Colistin. Results: For the combination of Meropenem and Colistin, 6 strains of A. baumannii and 3 strains of P. aeruginosa showed synergy while 5 strains of A. baumannii and 7 strains of P. aeruginosa showed additive effect, only 1 strain of P. aeruginosa showed antagonism. For Imipenem and Colistin, only 1 strain of A. baumannii and 3 strains of Pseudomonas showed synergy while 8 strains of Acinetobacter and 8 strains of Pseudomonas showed additive effect. Conclusion: The “in vitro” combination Colistin-Carbapenem is associated with an improvement in MIC. In the majority of the cases, this improvement suggests a synergistic combination or an additive effect.
文摘The relationship between antibiotic consumption and resistance has been widely evaluated. Pseudomonas aeruginosa is one of the most important opportunistic pathogens in the nosocomial setting, and its resistance to antibiotics is increaseing. Production of metallo-β-lactamases (MBLs) is currently the most fearful resistance mechanism due to the potential of dissemination. This study aimed to evaluate the correlation between antibiotic consumption (expressed in DDD/100 bed days) and resistance (expressed in % of isolates and patients) in different time periods for P. aeruginosa between 2006 and 2009 at Saint George Hospital University Medical Center (SGH-UMC), Beirut. Pearson correlation coefficients (r) were calculated and linear regression was performed. Detection of MBL-producing Imipenem resistant P. aeruginosa (IRPA) isolates between 2008 and 2009 was performed using three MBL screening methods: MBL Etest?, Imipenem/EDTA combined disk test and EDTA disk potentiation with four cephalosporins. The modified Hodge test was also performed. From 2006 till 2009, there was a trend of increasing resistance of P. aeruginosa to all antibiotics, and the highest % of resistance was for Ofloxacin. Concerning resistance expressed by isolates, high correlation coefficients resulted among Imipenem, Ciprofloxacin and Tazobactam consumption and resistance to these agents in the same year correlation;Ceftazidime and Ofloxacin consumption and resistance in the next year correlation;Gentamicin and Ofloxacin consumption and the change in resistance (ΔR). Concerning resistance expressed by patients, results were similar except for Ceftazidime and Ofloxacin correlation in the next year correlation. In MBL screening, three isolates gave accordance among 4 methods which showed a positive result. The correlation between antibiotic consumption and resistance is highly dependent on the kind of antibiotic, the organism and the time of correlation. Various MBL screening phenotypic methods on one isolate can increase accuracy and eliminate false positive and negative results.
