Quantitative Assessment of Combination Antimicrobial Therapy against Multidrug-Resistant Acinetobacter baumannii (original) (raw)
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Biomedical Research-tokyo, 2016
In recent years, Acinetobacter strains have emerged as one of the most important nosocomial pathogens, especially in patients admitted to an intensive care unit (ICU). The progressively increasing antibiotic resistance against A. baumannii is now a major problem in our country as it is throughout the world. This resistance against A.baumannii has increased and led clinicians to find alternative antibiotics or antibiotic combinations. In the present study, it is aimed to evaluate the interaction between colistinrifampicin, colistin-imipenem, tigecycline-rifampicin and tigecycline-imipenem antibiotic combinations using microdilution checkerboard and E-test methods against ten multidrug resistant A. baumannii strains. Since A. baumannii strains have become frequently observed as an infection factor and since antimicrobial resistance rates have increased, there should be newly developed drugs for better treatments. In this study, 50 A. baumannii strains were isolated from various clinic...
Antimicrobial susceptibility of clinical isolates of Acinetobacter baumannii
Diagnostic Microbiology and Infectious Disease, 1996
The in-vitro activity of 18 antimicrobial agents alone or in combination against 248 clinical isolates of Acinetobacter baumannii from Taiwan were tested by agar dilution. The MIC90s of ampicillin, amoxicillin, piperacillin, cefuroxime, cefotaxime, ceftriaxone, gentamicin, and amikacin were at least 128 μg/ml. Ceftazidime, cefepime, sulbactam, clavulanic acid, and tazobactam presented moderate activity with MIC90s of 32, 16, 16, 32, and 32 μg/ml, respectively. The increased activity of ampicillin/sulbactam, amoxicillin/clavulanic acid, and piperacillin/tazobactam was due to the intrinsic effect of sulbactam, clavulanic acid, and tazobactam, respectively. Imipenem, meropenem, and ciprofloxacin were the most active antimicrobial agents with MIC90s of 1, 1, and 0.5 μg/ml, respectively. Nineteen isolates (7.7%) were resistant to all aminoglycosides and β-lactam antibiotics, except carbapenems and ciprofloxacin. We are concerned about the multidrug resistance of A. baumannii in this study.
MULTI DRUG RESISTANT ACINETOBACTER BAUMANNII: A SYSTEMATIC REVIEW FOR MICROBIAL AND CLINICAL STUDY
Infections due to Mutli Drug Resistant A. baumannii (MDRAB) is now recognized as a major public health problem worldwide. The nosocomial infection due to MDRAB has leaded to increased in morbidity and mortality which has added noticeably to significant challenge to modern antibiotic therapy system. This is due to rapid phenomenon of A. baumannii to acquire antibiotic resistance. Thus, in this review the overview of current knowledge on epidemiology, infections, mechanism of resistance and effective treatment options are briefly highlighted.
FEMS Microbiology Letters, 2012
Various combinations of antibiotics are reported to show synergy in treating nosocomial infections with multidrug-resistant (MDR) Acinetobacter baumannii (A. baumannii). Here, we studied hospital-acquired outbreak strains of MDR A. baumannii to evaluate optimal combinations of antibiotics. One hundred and twenty-one strains were grouped into one major and one minor clonal group based on repetitive PCR amplification. Twenty representative strains were tested for antibiotic synergy using Etest ® . Five strains were further analyzed by analytical isoelectric focusing and PCR to identify b-lactamase genes or other antibiotic resistance determinants. Our investigation showed that the outbreak strains of MDR A. baumannii belonged to two dominant clones. A combination of colistin and doxycycline showed the best result, being additive or synergistic against 70% of tested strains. Antibiotic additivity was observed more frequently than synergy. Strains possessing the same clonality did not necessarily demonstrate the same response to antibiotic combinations in vitro. We conclude that the effect of antibiotic combinations on our outbreak strains of MDR A. baumannii seemed strain-specific. The bacterial response to antibiotic combinations is probably a result of complex interactions between multiple concomitant antibiotic resistance determinants in each strain.
Current control and treatment of multidrug-resistant Acinetobacter baumannii infections
The Lancet Infectious Diseases, 2008
Institutional outbreaks caused by Acinetobacter baumannii strains that have acquired multiple mechanisms of antimicrobial drug resistance constitute a growing public-health problem. Because of complex epidemiology, infection control of these outbreaks is diffi cult to attain. Identifi cation of potential common sources of an outbreak, through surveillance cultures and epidemiological typing studies, can aid in the implementation of specifi c control measures. Adherence to a series of infection control methods including strict environmental cleaning, eff ective sterilisation of reusable medical equipment, attention to proper hand hygiene practices, and use of contact precautions, together with appropriate administrative guidance and support, are required for the containment of an outbreak. Eff ective antibiotic treatment of A baumannii infections, such as ventilator-associated pneumonia and bloodstream infections, is also of paramount importance. Carbapenems have long been regarded as the agents of choice, but resistance rates have risen substantially in some areas. Sulbactam has been successfully used in the treatment of serious A baumannii infections; however, the activity of this agent against carbapenem-resistant isolates is decreasing. Polymyxins show reliable antimicrobial activity against A baumannii isolates. Available clinical reports, although consisting of smallsized studies, support their eff ectiveness and mitigate previous concerns for toxicity. Minocycline, and particularly its derivative, tigecycline, have shown high antimicrobial activity against A baumannii, though relevant clinical evidence is still scarce. Several issues regarding the optimum therapeutic choices for multidrug-resistant A baumannii infections need to be clarifi ed by future research.
2021
Background: Acinetobacter baumannii has emerged as a medically important pathogen because of the increasing number of infections produced by this organism over the preceding three decades and the global spread of strains with resistance to multiple antibiotic classes. Recently, a particular attention has been drawn to the study of the microbial persistence properties and their correlation with the rate of elimination from the source of infection, as well as the prognosis of the disease progression. Material and methods: There were examined 53 strains of A. baumannii, isolated from patients with trophic ulcers. The bacteriological examination, as well as tests on determining both the persistence factors and the antibiotic susceptibility of the isolated strains were carried out according to the current method. Results: A. baumannii strains were highly resistant to all antibiotics tested, 38 (71.7%) showed multidrug resistance. The studies regarding the persistence factors of A. baumannii strains, revealed that 100% exhibited an antilysosyme activity, 78.0%-anticomplementary activity, 73.6%-produce biofilms, 58.5%-hemolytic activity, 28.3% and 13.2%-lecithinase and plasma coagulation activity, respectively. Conclusions: Isolated strains showed higher level of antimicrobial resistance and multiple persistence factors. The study results proved that treatment of trophic ulcers is still a major problem, requiring rational monitoring and management strategies.
Bacterial Resistance of Acinetobacter baumannii: A Global Concern
Rovedar, 2022
Acinetobacter baumannii (A. baumannii), one of the five most important bacteria with global threat to human health due to constantly increasing resistance (ESKAPE organisms), identified as a enormous threat in healthcare facilities, can create antibiotic resistance. The implementation of early detection and identification of multidrugresistant A. baumannii is serious to control its spread. The this study presents the human infection of A. baumannii, pathological findings, virulence factors of A. baumannii, antibiotic resistance mechanisms, and the therapeutic options available for treating A. baumannii infections. The ability of A. baumannii to develop antibiotic resistance mechanisms allows the organism to prosper in hospital settings, facilitating the global spread of multidrug-resistant strains. To dominate this problem, knowledge of the pathogenesis and antibiotic resistance mechanisms of A. baumannii is important. As reported, A. baumannii resistance to aminoglycosides, fluoroquinolones, and carbapenems increased, and resistance to lipopeptides, such as polymyxin B and colistin, are lower compared to that of other antimicrobial drugs. Therefore, novel prevention and treatment strategies against A. baumannii infections are warranted.
Journal of Burn Care & Research, 2013
Acinetobacter baumannii represents a cunning pathogen with multiple resistance genes. The authors report their experience with the treatment of two multiple drug-resistant A. baumannii clones. At least one positive culture was noted in 359 patients and, 323 had sufficient data for analysis. Of these, 42 patients were colonized leaving 281 antibiotictreated infected patients. The average age was 48.1 ± 20.6 years (mean ± standard deviation), total body burn surface area involvement (TBSA) was 30.8 ± 25%. Inhalation injury was confirmed by bronchoscopy in 238 of 323 (74%) patients. The day to the first A. baumannii culture was 7.9 ± 8.9 and 6.5 ± 8.8 days for the colonized and infected patients, respectively. Survival to discharge was 95.4% for colonized patients and 77.1% for infected patients. A total of 1425 sputum cultures, 123 catheter cultures from 40 patients, 1130 blood cultures from 176 patients, and 1925 wound cultures were obtained from the 318 infected patients (14 cultures per patient). Imipenem-cilastatin was first used in 162 patients, ampicillin-sulbactam in 40 patients, and cephalosporin in 41 patients. Imipenem-cilastatin was combined with ampicillin-sulbactam in 18 patients. Imipenemcilastatin eradicated A. baumannii in 27%, caused persistence in 55%, and failure in 20%. Ampicillin-sulbactam eradicated A. baumannii in 17%, caused persistence in 51%, and failure in 34%. Imipenem-cilastatin combined with ampicillin-sulbactam eradicated 23% of the A. baumannii, with 54% persisting, and 23% failing therapy. Nonparametric analysis of three sets of 34 matched patients treated with imipenem-cilastatin, ampicillinsulbactam, or a cephalosporin showed little difference in treatment outcomes. More rapid fever resolution and fewer positive cultures were noted in the imipenem-cilastatin treated group; however, length of stay was not different.
PloS one, 2016
The study investigated the effect of antibiotic combinations against 20 clinical isolates of A. baumannii (seven colistin-resistant and 13 colistin-susceptible) with different resistance mechanisms. Clinical data, treatment, and patient mortality were evaluated. The following methods were used: MIC, PCRs, and outer membrane protein (OMP) analysis. Synergy was investigated using the checkerboard and time-kill methods. Clonality was evaluated by PFGE. Based on clonality, the whole genome sequence of six A. baumannii isolates was analyzed. All isolates were resistant to meropenem, rifampicin, and fosfomycin. OXA-23 and OXA-143 were the most frequent carbapenemases found. Four isolates showed loss of a 43kDa OMP. The colistin-susceptible isolates belonged to different clones and showed the highest synergistic effect with fosfomycin-amikacin. Among colistin-resistant isolates, the highest synergistic effect was observed with the combinations of colistin-rifampicin followed by colistin-va...