In vitro comparison of kanamycin, kanendomycin, gentamicin, amikacin, sisomicin, and dibekacin against 200 strains of Pseudomonas aeruginosa.
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The antimicrobial activity of kanamycin, kanendomycin, gentamicin, amikacin, sisomicin, and dibekacin against 200 strains of Pseudomonas aeruginosa was compared. Dibekacin was found to be the most active against the tested organisms, whereas the other aminoglycoside antibiotics fell in the following order of diminishing antibacterial potency: amikacin, sisomicin, gentamicin, kanendomycin, and kanamycin. Seven strains showed high-level resistance to gentamicin (minimal inhibitory concentration, 400 mug/ml), and two of them were also resistant to amikacin and sisomicin (minimal inhibitory concentration, 75 mug/ml). The minimal inhibitory concentration of dibekacin for these seven strains was 0.625 mug/ml. (+info)
Role of aminoglycoside 6'-acetyltransferase in a novel multiple aminoglycoside resistance of an actinomycete strain #8: inactivation of aminoglycosides with 6'-amino group except arbekacin and neomycin.
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From a rare actinomycete strain #8 isolated from soil as arbekacin (ABK) resistant, we cloned a gene segment (0.9 kb) conferring multiple resistance to aminoglycoside (AG) antibiotics with 6'-NH2 including semisynthetic ones except ABK and neomycin (NM). Enzymatic modification using cell free extracts from Streptomyces lividans TK21/pANT-S2 carrying the cloned gene revealed that the gene coded for an AG 6'-acetyltransferase [AAC(6')] capable of acetylating all of the tested AGs with 6'-NH2 including semisynthetic ones and astromicin. The substrate specificity of the enzyme was thus similar to that of AAC(6')-Ie of Enterococcus faecalis. Antibiotic assay revealed a weak but clear antibiotic activity of 6'-N-acetylABK (8% of ABK activity) in contrast with substantial inactivation by the AAC(6') of the other AGs including amikacin and isepamicin. The NM acetylation by the AAC(6') also did not result in NM inactivation. It seems thus likely that AAC(6')-dependent resistance to ABK and NM, if it emerges, will remain at low level. (+info)
In vitro activities of daptomycin, arbekacin, vancomycin, and gentamicin alone and/or in combination against glycopeptide intermediate-resistant Staphylococcus aureus in an infection model.
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Daptomycin, a lipopeptide antibiotic, has broad activity against gram-positive organisms, similar to vancomycin; however, its mechanism of action differs, resulting in interference with cell membrane transport and a more rapid bactericidal activity. In light of increasing need for alternative treatments against intermediate-resistant Staphylococcus aureus, there is revitalized interest in this antibiotic. We, therefore, evaluated the activity of daptomycin alone or in combination in an in vitro infection model against two glycopeptide intermediate-resistant S. aureus (GISA) isolates. Newly designed regimens of daptomycin at 4 and 6 mg/kg of body weight every 24 h (q24h) were compared to the previous regimen of 3 mg/kg q12h. Daptomycin MICs and minimal bactericidal concentrations (MBCs) (MIC/MBC) for Mu-50, HIP5836 (992), and MRSA-67 were 0.5/1.0, 0.5/1.0, and 0.125/0.5 microgram/ml, respectively. MICs and MBCs of arbekacin for the three strains were 2.0/8.0, 0. 125/0.5, and 0.125/0.25 microgram/ml, respectively. Vancomycin and gentamicin MICs and MBCs for the three strains were 8.0/8.0, 8.0/8.0, and 0.5/1.0 microgram/ml and 128/128, 0.5/1.0, and 0.25/0.5 microgram/ml, respectively. Our experience with daptomycin in an in vitro infection model has shown significant kill against the two GISA strains (Mu-50 and 992) (P < 0.03). We also noted that kill was related to a total dose effect for 992, in which simulated daptomycin in vivo dosages of 6 mg/kg q24h and 3 mg/kg q12h produced similar kill and 4 mg/kg q24h resulted in significant regrowth (P +info)
Prediction of plasma levels of aminoglycoside antibiotic in patients with severe illness by means of an artificial neural network simulator.
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PURPOSE: The purpose of this work was to predict plasma peak and trough levels of an aminoglycoside antibiotic in patients with severe illness in an intensive care unit by a novel approach. Plasma levels were predicted based on the values of 15 physiological measurements using an artificial neural network (ANN) simulator. METHOD: A data set of 15 physiological measurements for 30 patients was used to develop the model. The ANN structure consisted of three layers: an input layer comprised of 15 processing elements, a hidden layer comprised of 10 processing elements with a sigmoid function as an activation function, and an output layer of two processing elements (peak and trough levels). The weight between neurons was trained according to the delta rule back-propagation of errors algorithm. Predicted values were obtained by "leave-one-out" experiments by both ANN and multiple linear regression analysis (MLRA). RESULTS: The correlation coefficients between observed and predicted values obtained by ANN prediction using standardized data sets were r=0.825 and r=0.854 for peak and trough levels, respectively. The correlation coefficients obtained by MLRA were r=0. 037 and r=0.276 for peak and trough levels, respectively. These results indicate that ANN shows better performance in prediction of aminoglycoside plasma levels from patients' physiological measurements than MLRA. CONCLUSIONS: Prediction of plasma levels of antibiotic in patients with severe illness by ANN was superior to the standard statistical method. Standardization of input data was found to be important for better prediction. ANN has some advantages over standard statistical methods, as it can recognize complex relationships in the data. (+info)
Efficacy of ampicillin plus arbekacin in experimental rabbit endocarditis caused by an Enterococcus faecalis strain with high-level gentamicin resistance.
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Enterococcus faecalis LC40 is an ampicillin-susceptible clinical isolate with high-level gentamicin resistance due to the aac(6')-Ie-aph(2")-Ia aminoglycoside resistance gene. The combination of ampicillin plus arbekacin reduced mean bacterial vegetation counts significantly more than ampicillin alone or ampicillin plus gentamicin in a rabbit model of aortic-valve endocarditis caused by E. faecalis LC40. (+info)
In vitro antimicrobial activity of the aminoglycoside arbekacin tested against oxacillin-resistant Staphylococcus aureus isolated in Brazilian hospitals.
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Arbekacin is an aminoglycoside used in Japan for treating infections caused by gentamicin and oxacillin-resistant S. aureus (ORSA). The objective of this study was to determine the in vitro antimicrobial activity of arbekacin against 454 clinical isolates of ORSA. The isolates were consecutively collected between January and July, 2000, from patients hospitalized in 8 Brazilian medical centers. The antimicrobial susceptibility testing was performed by disk diffusion method according to NCCLS recommendations. The vast majority of the isolates, 453 strains (99.8%), were considered susceptible to arbekacin based on the criteria proposed by the Requirements for Antibiotic Products of Japan. Only 1 isolate (0.2%) was classified as resistant. On the other hand, high rates of resistance were demonstrated for other aminoglycosides, such as gentamicin (97.6% resistance) and amikacin (97.0% resistance). Resistance rate was also high for ciprofloxacin (98.0%). All isolates were considered susceptible to vancomycin. The excellent in vitro antimicrobial activity of arbekacin demonstrated in this study indicates that this antimicrobial agent may play an important role in the treatment of severe ORSA infections, especially those that show poor clinical response with vancomycin monotherapy. Since the aminoglycosides should not be used as monotherapy to treat Gram positive infections, further studies evaluating in vitro and in vivo synergistic activity of arbekacin combinations are necessary to clarify the clinical role of this aminoglycoside. (+info)
Neuromuscular blocking properties of some antibiotics in man.
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Neuromuscular blocking properties of ribostamycin (1 gm), dibecacin (100 mg) and tobramycin (60 mg) were studied in a man during anesthesia and surgery by observing the effects of these antibiotics on muscle twitch tension. These drugs alone did not show any neuromuscular blocking action in those therapeutic doses. However, during the recovery phase of d-tubocurarine block the intravenous administration of 1 gm of ribostamycin caused a fairly rapid decrease in twitch tension. Tobramycin 60 mg did not show any remarkable effect, but dibecacin 100 mg produced a slight potentiating effect on the action of d-tubocurarine. The enhancement of the action of d-tubocurarine was antagonized promptly by edrophonium and more slowly by calcium. (+info)
Comparative in vitro activities of SCE-129, sulbenicillin, gentamicin, and dibekacin against Pseudomonas.
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Against sulbenicillin- and gentamicin-susceptible strains of Pseudomonas aeruginosa, SCE-129 was about 10 times more active than sulbenicillin and had a similar activity to gentamicin and dibekacin. Sulbenicillin-resistant strains of P. aeruginosa were moderately resistant to SCE-129, whether these strains were gentamicin-resistant or not. Gentamicin-resistant strains of P. aeruginosa were resistant to dibekacin but not to SCE-129. Against P. maltophilia, the minimum inhibitory concentration of SCE-129 resembled those of sulbenicillin, gentamicin, and dibekacin. Most strains of P. cepacia were moderately resistant to SCE-129 and sulbenicillin and highly resistant to gentamicin and dibekacin. (+info)