Synergistic combination of colistin with imipenem, amikacine or ciprofloxacin against Acinetobacter baumannii and Pseudomonas aeruginosa carbapenem-resistant isolated in Annaba hospital Algeria (original) (raw)
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Synergistic Combination of Carbapenems and Colistin against P. aeruginosa and A. baumannii
Open Journal of Medical Microbiology, 2013
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 antibacterial 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 . 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.
Disease and Molecular Medicine, 2016
Acinetobacter baumannii has emerged as one of the most important nosocomial pathogens and multi-drug resistant (MDR) isolates are of great concern worldwide. The aim of the present study was to investigate the in vitro synergistic activity of colistin in combination with other antibiotics against MDR A. baumannii blood stream isolates. A total of 54 non-duplicate, MDR A. baumannii isolates from blood culture specimens obtained between June 2011 and July 2012 were included in the study. In vitro synergistic activity of colistin in combination with imipenem, tigecycline or cefoperazone-sulbactam against study isolates was investigated by Etest superimposing method and the fractional inhibitory concentration (FIC) index was calculated for each antibiotic combination. The most frequent synergistic effect of colistin was found in combination with tigecycline in only 7 isolates (13.0%). All three antibiotics were found to have synergistic effect with colistin in four isolates (7.4%). Of isolates, 46 (85.2%) showed additive effect of colistin in combination with cefoperazone-sulbactam or tigecycline, 45 (83.3%) with imipenem. We found synergistic activity of colistin with other antibiotics in only a small number of isolates. Although Etest method is a practical method to investigate the synergistic activity, in case of choosing empirical treatment, colistin in combination with another antibiotic may be preferred.
Journal of Medical Microbiology, 2015
Acinetobacter baumannii has become one of the major infection threats in intensive care units (ICUs) globally. Since 2008, A. baumannii has been the leading cause of ventilator-associated pneumonia (VAP) in our ICU at an infectious disease hospital in southern Vietnam. The emergence of this pathogen in our setting is consistent with the persistence of a specific clone exhibiting resistance to carbapenems. Antimicrobial combinations may be a strategy to treat infections caused by these carbapenem-resistant A. baumannii. Therefore, we assessed potential antimicrobial combinations against local carbapenem-resistant A. baumannii by measuring in vitro interactions of colistin with four antimicrobials that are locally certified for treating VAP. We first performed antimicrobial susceptibility testing and multilocus variable number tandem repeat analysis (MLVA) genotyping on 74 A. baumannii isolated from quantitative tracheal aspirates from patients with VAP over an 18-month period. These 74 isolates could be subdivided into 21 main clusters by MLVA and .80 % were resistant to carbapenems. We selected 56 representative isolates for in vitro combination synergy testing. Synergy was observed in four (7 %), seven (13 %), 20 (36 %) and 38 (68 %) isolates with combinations of colistin with ceftazidime, ceftriaxone, imipenem and meropenem, respectively. Notably, more carbapenem-resistant A. baumannii isolates (36/43; 84 %) exhibited synergistic activity with a
Journal of Medical Microbiology, 2015
Acinetobacter baumannii has become one of the major infection threats in intensive care units (ICUs) globally. Since 2008, A. baumannii has been the leading cause of ventilator-associated pneumonia (VAP) in our ICU at an infectious disease hospital in southern Vietnam. The emergence of this pathogen in our setting is consistent with the persistence of a specific clone exhibiting resistance to carbapenems. Antimicrobial combinations may be a strategy to treat infections caused by these carbapenem-resistant A. baumannii. Therefore, we assessed potential antimicrobial combinations against local carbapenem-resistant A. baumannii by measuring in vitro interactions of colistin with four antimicrobials that are locally certified for treating VAP. We first performed antimicrobial susceptibility testing and multilocus variable number tandem repeat analysis (MLVA) genotyping on 74 A. baumannii isolated from quantitative tracheal aspirates from patients with VAP over an 18-month period. These 74 isolates could be subdivided into 21 main clusters by MLVA and .80 % were resistant to carbapenems. We selected 56 representative isolates for in vitro combination synergy testing. Synergy was observed in four (7 %), seven (13 %), 20 (36 %) and 38 (68 %) isolates with combinations of colistin with ceftazidime, ceftriaxone, imipenem and meropenem, respectively. Notably, more carbapenem-resistant A. baumannii isolates (36/43; 84 %) exhibited synergistic activity with a
Molecules
Carbapenem-resistant Acinetobacter baumannii (CR-Ab) infections are associated with high morbidity and mortality. The aim of the study was to evaluate the in-vitro activity of different antimicrobial combinations (with and without colistin, COL) against clinical isolates of CR-Ab collected from patients with CR-Ab infection, including unconventional combinations such as COL + VANcomycin (VAN) and COL + rifampin (RIF). CR-Ab strains were collected from hospitalized patients at Sapienza University of Rome. Antimicrobial susceptibility patterns were determined throughout MIC50/90s whereas the synergistic activity was evaluated by qualitative (i.e., checkerboard) and quantitative (i.e., killing studies) methods. All the strains were found oxacillinase (OXA) producers and tigecycline (TIG) sensitive whereas 2 strains were resistant to COL. Application of the checkerboard method indicated complete synergism in COL combinations at different extension: 21.4%, 57.1%, 42.8%, 35.7% for COL + m...
International Journal of Innovation and Applied Studies, 2014
Background: Acinetobacter baumannii (A. baumannii) is one of the most important nosocomial pathogens, Increasing resistance coupled with the fact that few novel antibiotics are currently available or in the pipeline, leaves patients and physicians with a very limited armamentarium against these pathogens. Combination therapies are considered as effective options to overcome this matter. Materials and methods: Fifty A. baumannii isolates were collected from clinical specimens, from patients in ICU at Ibn Sina Hospital in Rabat, Morocco during the January 2011-January 2012 period. Antimicrobial susceptibilities to amikacin, ceftazidime, ciprofloxacin, amoxcicillin-clavulanic-acid and imipenem were determined by disk diffusion and the E-test method was used to determine antimicrobial susceptibility and the MIC for colistin, imipenem, rifampicin and for the combinations tests. Results: 76% of A. baumannii isolates were MDR to antibiotics (amoxcicilline + clavulanic acid, imepenem, ciprofloxacin, amikacin, ceftazidim, rifampicin) unless colistin. 100%, 26%,and 14% of isolates were susceptible to colistin, imipenem, and rifampicin, respectively. The MIC50 and MIC90 of imipenem were 24µg/ml and >32 µg/ respectively. The MIC50 and MIC90 of rifampicin were 4 µg/ml and 6 µg/ml, respectively. Imipenem associated with rifampin or with colistin and imipenem alone had the percentages of the rate sensitivity; 28%, 28% and 26%, respectively. Conclusion: the findings of this study indicate that colistin has the best activity against A. baumannii, whereas imipenem in combination with colistin or rifampicin still a good choice to treat nosocomial infections due to multiresistant A.baumannii.
Microbes and Infectious Diseases, 2021
Background: Acinetobacter baumannii (A. baumannii) has emerged as a nosocomial pathogen especially in the intensive care units (ICUs). It's enlisted at the top of urgent threat level organisms in centers for disease control and prevention (CDC's) antibiotic resistance threats report. Objectives: To assess prevalence, risk factors of health care associated infection by A. baumannii, and to compare the in-vitro efficacy of colistin sulfate-tigecycline combinations versus their individual combination with levofloxacin and meropenem against carbapenem resistant A. baumannii clinical isolates from an Egyptian tertiary care hospital ICUs. Methods: The study included 250 ICU patients, samples were collected according to the site of infection. Acinetobacter baumannii was isolated, identified and tested for antibiotic susceptibility by disc diffusion. Broth microdilution method was used for assessment of colistin, tigecycline, levofloxacin, and meropenem. Thirty isolates resistant to all carbapenems were tested by the checkerboard method to assess effect of antibiotic combinations. Results: forty-six A. baumannii were isolated, with highest prevalence in respiratory secretions. Prior antibiotic administration and failure of empirical antibiotic therapy were found to be a major risk factors of infections by A. baumannii. Colistin combination with meropenem showed the highest synergy (50%). Tigecycline-meropenem combination had the highest antagonistic effect (66.7%). Conclusion: No antagonistic effect of colistin combination with meropenem was confirmed in this study. Only colistin-based combinations, particularly those with meropenem may confer therapeutic benefits against carbapenem-resistant A. baumannii.