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Query: UMLS:C0026918 (Mycobacterium)
 52,428 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Minimal inhibitory and bactericidal concentrations (MIC and MBC) of clarithromycin were determined with 49 Mycobacterium avium strains isolated from patients with acquired immunodeficiency syndrome. The inhibitory activity depended on the pH of the medium: the drug was more active at pH 7.4 and less active at pH 5.0, with activity at pH 6.8 in an intermediate position. The broth-determined MIC found at pH 7.4 were 0.25 and 0.5 micrograms/ml for most strains. The agar-determined MIC for most strains ranged from 1.0 to 4.0 micrograms/ml. The MBC of the drug were 8- to 64-fold higher than the MIC, which indicates that the efficacy of clarithromycin can be associated with its inhibitory rather than its bactericidal activity.
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PMID:Clarithromycin minimal inhibitory and bactericidal concentrations against Mycobacterium avium. 153 86

Minimal inhibitory and bactericidal concentrations (MIC and MBC) of isoniazid and ethionamide were determined in 7H12 broth in experiments with 68 Mycobacterium avium strains and 14 wild drug-susceptible M. tuberculosis strains. MICs of isoniazid for M. tuberculosis were from 0.025 to 0.05 microgram/ml, and for M. avium from 0.6 to greater than 10.0 micrograms/ml. MICs of ethionamide for M. tuberculosis were from 0.3 to 1.25 micrograms/ml, and 42.7% of M. avium strains were within the same range. Isoniazid and ethionamide were highly bactericidal against M. tuberculosis, but they had very low bactericidal activity against M. avium.
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PMID:Comparison of bacteriostatic and bactericidal activity of isoniazid and ethionamide against Mycobacterium avium and Mycobacterium tuberculosis. 189 26

The lyophilized aqueous extract (LWE) from the leaves of Phyllanthus discoideus was found to show an antibacterial activity. The alkaloid fraction obtained from LWE inhibited the growth of Escherichia coli and Enterococcus faecium (MIC = 1.6 mg/ml), Pseudomonas aeruginosa (MIC = 0.78 mg/ml), Staphylococcus aureus and Mycobacterium smegmatis (MIC = 0.2 mg/ml). Among the alkaloids identified, viroallosecurinine and securinine showed a high activity. Viroallosecurinine exhibited a MIC of 0.48 micrograms/ml for Ps. aeruginosa and Staph. aureus. This alkaloid is bactericidal since the yields of MIC/MBC were less than 1. The MIC of securinine was 0.500 mg/ml for E. coli, Staph. aureus and Myc. smegmatis. These effects of Phyllanthus discoideus leaf extracts support some of the local uses of the plant in traditional therapy.
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PMID:Antibacterial activity of the leaves of Phyllanthus discoideus. 215 12

The bactericidal activities of four injectable antituberculosis drugs, streptomycin, amikacin, kanamycin, and capreomycin, against Mycobacterium avium and M. tuberculosis were tested. All four drugs were highly bactericidal against M. tuberculosis, with low MBC/MIC ratios and MBCs significantly lower than the maximum achievalbe concentrations in serum (Cmax). In contrast, all four drugs had very low bactericidal activities against M. avium: the broth-determined MBCs were significantly higher than the Cmax. On a basis of comparisons with the broth-determined MICs found for susceptible M. tuberculosis strains and with the Cmax, about one-third of 100 M. avium strains tested can be tentatively considered as susceptible to three aminoglycosides (streptomycin, amikacin, and kanamycin) but not to capreomycin. In regard to the MBCs and MICs, the three aminoglycosides tested have about identical potentials as drugs of choice in combination with other drugs for chemotherapy of M. avium disease. The low bactericidal activities of these drugs against M. avium in vitro do not exclude their therapeutic usefulness, because they may produce a synergistic effect in combination with other drugs. Such an option is especially promising for patients whose isolates can be considered susceptible on the basis of the MIC. We found no differences in susceptibility to the four drugs tested for M. avium strains (identified by Gen-Probe) isolated from 50 patients with and 50 patients without acquired immune deficiency syndrome.
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PMID:Comparison of bactericidal activities of streptomycin, amikacin, kanamycin, and capreomycin against Mycobacterium avium and M. tuberculosis. 232 85

We determined the MICs of ethambutol for both Mycobacterium avium and Mycobacterium tuberculosis strains by using broth dilution (7H12 broth, radiometric method) and agar dilution (7H11 agar) methods. We found the MICs to be much lower in liquid than in solid medium. The broth-determined MICs for susceptible M. tuberculosis and most of the M. avium strains were comparable to the levels in blood of patients, being lower than the peak levels. We propose that the MICs, determined radiometrically in in 7H12 broth, be considered as tentative criteria for susceptibility testing of M. avium isolates in future clinical trials. The use of these values instead of critical concentrations should also be considered as an alternative to the conventional susceptibility testing method in chemotherapy of tuberculosis. Ethambutol produced bactericidal effects against both M. tuberculosis and M. avium, and the MIC/MBC ratios were in the same range for both species when MICs and MBCs were tested in 7H12 broth by conventional sampling and plating.
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PMID:Ethambutol MICs and MBCs for Mycobacterium avium complex and Mycobacterium tuberculosis. 310 88

A review is given of the microbiological properties of imipenem, a new carbapenem antibiotic with an exceptionally broad spectrum of antibacterial activity. An evaluation of results of numerous in vitro studies reveals that imipenem effectively inhibited growth of 53 of 55 bacterial species, the mean MIC90 being less than 8 mg/l. The MIC90 for cocci, with the exception of Staphylococcus epidermidis, is in the range of 0.01-3.1 mg/l. The MIC90 for all Enterobacteriaceae is equal to or less than 8 mg/l. Pseudomonas aeruginosa and other non-fermentative gram-negative bacteria are generally susceptible to imipenem, only Pseudomonas maltophilia and Pseudomonas cepacia showing intrinsic resistance. Imipenem is currently the most active drug available against anaerobic bacteria, the MIC usually being below 1 mg/l even for Bacteroides fragilis. Rare bacteria such as Nocardia asteroides, Listeria monocytogenes or fast growing Mycobacterium spp. which cause difficult-to-treat infections are also susceptible to imipenem. Increases in inoculum size have only a minimal effect on activity of the drug. In most species the MBC only slightly exceeded the MIC; however in the case of Streptococcus faecalis the MBC value was many times the MIC value. Synergism has been observed in combinations of imipenem with aminoglycosides, and antagonism in combinations with other beta-lactam antibiotics against Pseudomonas aeruginosa and Serratia marcescens. Imipenem is stable in the presence of the common chromosomal and plasmid-mediated enzymes. Induction of inactivating enzymes was observed in staphylococci, Pseudomonas aeruginosa and Serratia marcescens.
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PMID:In vitro activity of imipenem--a review. 638 25

We investigated the activity of benzoxazinorifamycin (KRM-1648) against several drug-susceptible and multidrug-resistant strains of tubercle bacilli. Since KRM-1648 is a rifamycin derivative, we included some strains of Mycobacterium tuberculosis resistant to rifampin (RIF) among the multidrug-resistant strains. For RIF-susceptible strains, the MIC of KRM-1648 was much lower than that of RIF (MICs of KRM-1648 and RIF at which 90% of strains are inhibited, < or = 0.015 and < or = 0.25 micrograms/ml, respectively). The MBC of KRM-1648 (range, 0.007 to 0.03 microgram/ml) was also much lower than that of RIF (range, 0.5 to 1.0 microgram/ml). Postantibiotic effect studies with KRM-1648 showed a rapid reduction in the CFU counts with an exposure of 24 h or more, and its sterilizing effect was maintained even up to 21 days thereafter. Parallel postantibiotic effect studies with RIF showed a less significant effect with a faster recovery of growth, and RIF failed to sterilize the organisms even after 72 h of exposure. KRM-1648 at 0.125 and 0.25 microgram/ml caused complete inhibition of intracellular growth of M. tuberculosis in J774 A.1 macrophages after 48 h of exposure. After a similar exposure time RIF at a concentration of 0.25 microgram/ml caused complete inhibition of growth, but a concentration of 0.125 microgram/ml caused only a 50% reduction in growth compared with that of controls at day 7. With 24 h of pulsed exposure of the intracellular organisms to 0.25 micrograms of the drugs per ml, KRM-1648 caused complete inhibition of intracellular growth, while RIF caused only moderate inhibition of intracellular growth. These findings suggest that KRM-1648 is a potentially useful drug for the treatment of tuberculosis.
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PMID:In vitro activity of the benzoxazinorifamycin KRM-1648 against drug-susceptible and multidrug-resistant tubercle bacilli. 772 12

Twenty clinical isolates of Mycobacterium avium-intracellulare were tested with amikacin and sulphamethoxazole for in-vitro susceptibilities. The MICs and MBCs of the former drug ranged from 8 to > 64 mg/L (median MIC: 64 mg/L, median MBC: > 64 mg/L). The MICs and MBCs of the latter drug were found to be > 256 mg/L. Each of eight patients with invasive pulmonary disease due to these organisms was treated with amikacin for six months and with cotrimoxazole (sulphamethoxazole-trimethoprim) for one year. Only one patient had sustained bacteriological conversion. Three patients showed a transient reduction of bacillary load during the period of amikacin administration. The rest all failed to show response. Thus sulphamethoxazole was found to have no activity against Mycobacterium avium-intracellulare, and amikacin has doubtful activity when used alone in treatment of M. avium-intracellulare infection.
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PMID:Lack of activities of amikacin and sulphamethoxazole against Mycobacterium avium-intracellulare. 835 90

The in vitro and in vivo activities of a new rifamycin derivative, KRM-1648, against Mycobacterium tuberculosis H37Rv were compared with those of rifampin. Bactericidal activity was evaluated by using a silicone-coated slide culture method. The MBC of KRM-1648 was 0.15 to 0.3 microgram/ml for 24 h of exposure, while that of rifampin was > 160 microgram/ml under the same conditions. Against experimental murine tuberculosis, KRM-1648 exhibited significant therapeutic effects, in terms of prolonged survival times for mice compared with those with rifampin treatment, even at lower doses, such as 1 and 3 mg/kg. At a dose of 3 mg/kg, KRM-1648 was at least as effective as rifampin at 10 mg/kg. The combination of KRM-1648 (3 mg/kg) plus isoniazid (3 mg/kg) plus ethambutol (10 mg/kg) exhibited much more activity than did rifampin (10 mg/kg) plus isoniazid (3 mg/kg) plus ethambutol (10 mg/kg). These findings suggest that KRM-1648 is a promising candidate for the treatment of tuberculosis.
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PMID:In vitro bactericidal and in vivo therapeutic activities of a new rifamycin derivative, KRM-1648, against Mycobacterium tuberculosis. 883 91

Aminoglycoside-aminocyclitols including streptomycin, kanamycin, capreomycin and amikacin showed considerable activity against Mycobacterium tuberculosis, with MICs well below their Cmax and relatively low MBC/MIC ratios. Kanamycin, capreomycin and amikacin remained highly active against 'resistant' and 'multidrug-resistant' M. tuberculosis isolates except for some 'multidrug-resistant' isolates which showed complete cross-resistance between streptomycin and the selected 2-deoxystreptamines. Gentamicin displayed anti-tuberculous activity but was bacteriostatic only. Non-tuberculosis mycobacteria, in particular Mycobacterium chelonae and Mycobacterium avium-intracellulare, were more resistant than M. tuberculosis. Amikacin was inhibitory against Mycobacterium kanasii, Mycobacterium scrofulaceum and Mycobacterium fortuitum, but was bactericidal against M. scrofulaceum only. Kanamycin was also bactericidal against M. scrofulaceum. Growth of M. fortuitum was inhibited by amikacin and neomycin which was also inhibitory against M. tuberculosis and M. scrofulaceum. Although the application of neomycin has been limited by its high toxicity, this study suggested that this drug might be useful as a topical agent for cutaneous infections by M. fortuitum.
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PMID:In-vitro activities of aminoglycoside-aminocyclitols against mycobacteria. 924 1


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