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Query: UNIPROT:Q29983 (MIC)
 21,138 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The clinical relevance of in vitro tests of antimicrobial activity, other than simple MIC and MBC observations, is increasingly recognised. Such tests include bacterial time-kill studies and post-antibiotic effect (PAE). The authors have studied these parameters in 11 Gram-negative and Gram-positive strains, all clinical isolates. Viable counts were done at 0, 2, 4, 6 and 24 h by a new microtitre method, and PAE was studied by both conventional methodology and by use of the Malthus Microbial Growth Analyser. Bacterial kill was inoculum-dependent and kill at high inocula concentration-dependent. No paradoxical reduction in kill was seen at high concentrations of ciprofloxacin (200 x MBC). PAE was concentration-dependent and addition of gentamicin can prolong PAE. Reduced sensitivity to further antibiotic exposure in the PAE period (adaptive resistance) was noticed and was dependent on antibiotic concentration in the first exposure. The significance of these findings to new dosage schemes is discussed. To optimise therapy in seriously ill patients, it may be relevant to increase the dose of ciprofloxacin currently used for treating serious infection.
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PMID:Concentration-dependent bacterial killing, adaptive resistance and post-antibiotic effect of ciprofloxacin alone and in combination with gentamicin. 213 4

The authors compared the in vitro activity of imipenem, ceftazidime and cefotaxime against 100 strains of Acinetobacter calcoaceticus isolated in 1986 and 1987. The minimal inhibitory and bactericidal concentrations (MICs and MBCs) were determined by the agar dilution and broth microdilution methods respectively, with and without 50 per cent of human serum in the medium to evaluate the possible influence of protein binding. Imipenem was the most active of the three drugs against Acinetobacter, including beta-lactamase producing strains. The MICs 50 and 90 of imipenem were 0.18 micrograms/ml and 0.48 micrograms/ml respectively, as opposed to 5.16 and 14.61 micrograms/ml for ceftazidime, 16 and 75.6 micrograms/ml for cefotaxime. No change was noted in the susceptibility of Acinetobacter to imipenem from 1981 to 1987. The geometric mean MIC of imipenem was 0.25 micrograms/ml. Susceptibility remained unchanged for ceftazidime and cefotaxime but the geometric mean MICs were higher, being 7.29 and 22.8 micrograms/ml respectively. Imipenem had the highest bactericidal activity, with a mean MBC/MIC ratio of 1.16. The presence of human serum did not influence the results, due to the low protein binding of all three antibiotics. It is concluded that imipenem is one of the major antibiotics available for the treatment of nosocomial Acinetobacter infections. However, a few resistant strains have recently been isolated, confirming the need for epidemiological surveillance of bacterial resistance to this antibiotic.
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PMID:[Comparative activity of imipenem, ceftazidime and cefotaxime against Acinetobacter calcoaceticus]. 213 37

Macrolide antibiotics, commonly used in upper and lower respiratory tract infections, are inconsistently active against Haemophilus influenzae. The new azalide, azithromycin, was compared with erythromycin and roxithromycin against this pathogen. Azithromycin (MIC range 0.06-1 mg/l) was four to eight times more potent than erythromycin (MIC range 0.5-8 mg/l) and roxithromycin (MIC range 0.5-16 mg/l). At 1 mg/l, 100% of the strains of H. influenzae were inhibited by azithromycin compared with 16% with erythromycin and 5% with roxithromycin. Azithromycin exhibited a rapid bactericidal effect, with a 99.9% kill at 4 h. The MBC was equal to or up to four-times greater than the MIC.
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PMID:Bacteriostatic and bactericidal activity of azithromycin against Haemophilus influenzae. 215 34

We evaluated the efficacy of azithromycin, erythromycin and doxycycline in controlling in-vitro propagation of Chlamydia trachomatis in HeLa 229 cells. Eight recent clinical isolates of C. trachomatis and two fast-growing strains were tested with inocula of 10(3)-10(5) inclusion forming units per well of a 96-well microtitre plate. C. trachomatis inclusions were detected by an immunoperoxidase-antiperoxidase procedure (PAP), including a genus-specific monoclonal antibody. MIC ranges were 0.064-0.25 mg/l azithromycin, 0.064-0.128 mg/l erythromycin and 0.016-0.064 mg/l doxycyline; MBC ranges were 2-8 mg/l azithromycin, 4-64 mg/l erythromycin and 0.5-8 mg/l doxycycline. Since azithromycin appears to be effective against C. trachomatis, clinical studies in sexually transmitted diseases are indicated.
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PMID:In-vitro activity of azithromycin against Chlamydia trachomatis. 215 40

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

Phase-contrast microscopy, killing-curves and turbidimetric growth-curves were used in a comparative study of the antibacterial effects of a new carbapenem, meropenem (SM 7338) and imipenem on five strains of Proteus mirabilis. Despite the low MIC (0.2 mg/l) of imipenem for the five strains included in our study, the MBC remained relatively high (4.4 mg/l). During the first few hours of incubation, imipenem induced large lemon-shaped cells while the turbidity increased without substantial changes in culture viability. Later, most of the cell-wall deficient bacteria generated small spheroplasts until the antibiotic concentration exceeded 32 times the MIC. The MIC of meropenem was lower (0.03 mg/l) with an MBC (0.08 mg/l) very close to the MIC. Meropenem also induced large bodies but these cell-wall deficient bacteria did not generate small round bodies as observed with imipenem. In conclusion, imipenem produced in strains of Pr. mirabilis an amdinocillin-like change in cell morphology, responsible for the discrepancies observed between MIC and MBC. This effect was not observed with meropenem.
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PMID:Antibacterial effect of meropenem and imipenem on Proteus mirabilis. 221 55

Sixteen patients with acute meningitis caused by Gram-negative bacteria were treated with pefloxacin intravenously. The age range of the patient group was six months to 85 years with a mean age of 40 years; three patients were children. In all but two patients meningitis was a complication of neurosurgical operations and fourteen of the sixteen had received prior therapy which was not successful. The causative organisms were: Pseudomonas aeruginosa (5), Acinetobacter calcoaceticus (4), Klebsiella pneumoniae (3), Enterobacter cloacae (2), Citrobacter diversus (1) and Salmonella group C (1). Pefloxacin was administered intravenously 800 mg twice a day to the adult patients (mean dosage of 21( +/- 6.7) mg/kg body weight) for a mean period ( +/- S.D.) of 11( +/- 4) days. The mean cerebrospinal fluid concentration of pefloxacin was 8.8( +/- 5.0) mg/l which was 54% of the mean peak serum concentration (16.3( +/- 8.8]. The mean MIC and MBC of the causative organisms were 1.1( +/- 1.2) mg/l and 1.64( +/- 1.2) mg/l. Thirteen patients (87%) were cured or clinically improved and twelve (80%) were bacteriologically cured. One patient failed, another patient had reinfection and one was not assessable. No side effects were observed. In the present study pefloxacin offered an efficacious and safe treatment of Gram-negative meningitis following failure of other antibiotic therapy.
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PMID:Pefloxacin efficacy in gram-negative bacillary meningitis. 225 48

The clinical findings relating to 11 patients in Hong Kong (HK) and to 43 patients described elsewhere, all with Streptococcus zooepidemicus septicaemia, are reviewed. There was a particular association with cardiovascular disease (27%) with seven cases of endocarditis, three of abdominal aortic aneurysm and two of deep venous thrombosis. Associations not previously reported included two cases of pharyngitis and two patients with persistent post-operative fever. The overall mortality was 22%. Both human and porcine strains of S. zooepidemicus from HK did not hydrolyse aesculin in contrast to the aesculin-positive biotypes reported previously. HK strains also had very mucoid colonies and capsules of hyaluronic acid were seen in electron micrographs. Samples of chromosomal DNA, extracted by means of HindIII restriction endonuclease, of strains from human beings and pigs were identical. The MIC of penicillin for all strains was less than or equal to 0.03 mg/l but the MBC for all was greater than 32 mg/l. Penicillin alone is generally sufficient for cure but combination with an aminoglycoside may be indicated in seriously ill patients. In our locality, pigs were incriminated as a possible source of human infection whereas consumption of contaminated dairy products is important elsewhere.
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PMID:Streptococcus zooepidemicus (Lancefield group C) septicaemia in Hong Kong. 227 71

Compounds having alpha-[dihydro-5-substituted 6-thioxo-2H- 1,3,5-thiadiazine-3(4H)-yl]benzylpenicillin structure were synthesized by the reaction of ampicillin trihydrate, formaldehyde and dithiocarbamic acid salts. The structures were evident from chemical and spectral analysis. The antimicrobial activities of the compounds were investigated against some gram-positive (Staphylococcus aureus and Streptococcus faecalis) and gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria and some yeast-like fungi (Candida albicans, C. parapsilosis, C. stellatoidea and C. pseudotropicalis) and molds such as Trichophyton rubrum, T. mentagrophytes, Microsporum canis, M. gypseum, Penicillium and Aspergillus by the tube dilution method. In addition to MIC (minimal inhibitory concentration), MBC (minimal bactericidal concentration) and MFC (minimal fungicidal concentration) values were determined using ampicillin trihydrate as standard. The compounds synthesized were usually found as effective as ampicillin trihydrate against S. aureus and S. faecalis and less effective than ampicillin trihydrate against E. coli. Both the compounds synthesized and ampicillin trihydrate are ineffective in the concentrations studied against P. aeruginosa. Compound 10 and 11 are more effective against all the yeast-like fungi than the other compounds and ampicillin trihydrate.
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PMID:Synthesis and antimicrobial activities of some new tetrahydro-2H-1,3,5-thiadiazine-2-thione derivatives of ampicillin. 228 82

The in vitro susceptibility of 55 strains of subgingival plaque bacteria to minocycline was determined. A concentration of 1 microgram/ml minocycline was found to inhibit 85% of the strains tested and the MIC ranged from 0.03 to 32 micrograms/ml. For 71% of the strains tested the MBC was at least 4 times greater than the corresponding MIC, suggesting a bacteriostatic activity for minocycline. A concentration of 20 mg/ml of magnesium ions was capable of neutralizing 8 micrograms/ml of minocycline and was used to eliminate "carry-over" effects inherent in the experimental procedure. After 6 to 7 weeks exposure to sub-lethal concentrations of minocycline there was no appreciable increase in the MICs of most organisms with the exception of Actinobacillus actinomycetemcomitans NCTC 10981 and Campylobacter concisus NCTC 11485. Short term (6 hour exposure of bacteria to minocycline (8 micrograms/ml) markedly reduced the viability of a number of periodontopathogens but had little effect on the viability of Veillonella parvula NCTC 11456 and Fusobacterium nucleatum NCTC 11326. These in vitro investigations have demonstrated that minocycline is capable of inhibiting most of the periodontitis-associated bacteria tested and can kill some of these bacteria after a comparatively short exposure time. However, some of the organisms tested exhibited a low susceptibility to minocycline and others became less susceptible following exposure to low concentrations of the antibiotic for several weeks.
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PMID:Susceptibility and resistance of plaque bacteria to minocycline. 232 22


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