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PubMed1982

[Circular dichroism study of amphotericin B interaction with the sterols of Candida albicans strains sensitive and resistant to polyene antibiotics].

The method of circular dichroism (CD) was used to study interaction of amphotericin B with liposomes of egg lecithin containing sterols isolated from sensitive and resistant strains of Candida albicans. Analysis of the CD spectra showed that the antibiotic spectral parameters in the dispersion of liposomes modified with sterols underlie definite changes. In case of sterol isolated from the sensitive culture they were evident from an increase in the relative intensity of the negative extremes at 415, 390 and 370 nm. The contours of the CD spectrum in the region of 350 nm significantly changed proportionally to the antibiotic concentration and during incubation. The CD spectra of amphotericin B in the dispersions of the lecithin liposomes containing sterols isolated from the resistant strain of C. albicans were characterized by an increase in the relative intensity of the negative extremes at 415, 390 and 370 nm. These changes also took place during incubation. Still, the frequency character of the spectrum did not practically change. Only the intensity in the spectral region tested somewhat changed proportionally within an hour. The results indicate that the character of antibiotic interaction with liposomes containing sterols of the sensitive and resistant cultures significantly differs. This means that the changes in the membrane sterol composition (ergosterol and delta 7.22-ergostadien-3 beta-ol were the main sterols of the sensitive and resistant cultures respectively) have a marked effect on the character of the antibiotic interaction with them.

Amphotericin B↗
PubMed1993

4-Quinolone bactericidal mechanisms.

The bactericidal activity of nalidixic acid against Escherichia coli strain KL16 in nutrient broth was abolished by the addition of rifampicin. Cells suspended in phosphate-buffered normal saline (PBS) were also not killed by nalidixic acid. Experiments with modern 4-quinolones showed their activities varied according to the conditions under which they were tested. Rifampicin did not affect the concentration at which ofloxacin became bactericidal in nutrient broth, but did limit the extent of ofloxacin-induced death. However, rifampicin produced a 10-fold increase in the concentration at which ciprofloxacin became bactericidal in nutrient broth, and completely abolished the bactericidal activity of norfloxacin. Unlike nalidixic acid all of the modern 4-quinolones killed cells suspended in PBS. Based on these results it was possible to differentiate 3 processes by which 4-quinolones induced death. Mechanism A was only active against dividing bacteria and required RNA and protein synthesis; it was therefore not active against bacteria suspended in PBS and was inhibited in nutrient broth by the addition of rifampicin. Mechanism B required neither RNA nor protein synthesis and was also active against non-dividing bacteria; it was therefore not inhibited by rifampicin nor by suspending bacteria in PBS. Mechanism C killed non-dividing bacteria, but required protein and RNA synthesis: it therefore functioned in PBS, but was inhibited by rifampicin.(ABSTRACT TRUNCATED AT 250 WORDS)

4-Quinolones↗
PubMed1994

Susceptibility of methicillin-resistant Staphylococcus aureus clinical isolates to various antimicrobial agents. IV. Aminoglycoside-modifying enzyme AAC(6')/APH(2") is responsible for arbekacin-resistance enhanced by bleomycin.

Resistance patterns against various antimicrobial agents including beta-lactams, aminoglycosides, tetracyclines, fluoroquinolones, macrolides were examined for 58 strains of methicillin-resistant Staphylococcus aureus (MRSA) isolated at Hiroshima University Hospital from April to November 1992. All the MRSA strains produced type II-coagulase but not beta-lactamase. Regarding aminoglycoside-modifying enzymes, 7 strains (12%) appeared to be producing aminoglycoside 4',4"-adenyltransferase AAD(4',4") encoded by aadD without coproduction of bifunctional aminoglycoside 6'-acetyltransferase/2"-phosphotransferase AAC(6')/APH(2") encoded by aacA-aphD (referred to as tobramycin-resistant type, TOBr). The remaining 51 strains (88%) were phenotypically producers of both enzymes (i.e., mix-resistant type, Mixr). AAD(4',4"), encoded by aadD which was reported to be closely linked with bleomycin (BLM)-resistance determinant, could be seen in 100% MRSA strains and ca. 90% strains expressed AAC(6')/APH(2"). BLM endowed Mixr-type but not TOBr-type MRSA strain with enhanced resistance to arbekacin (ABK) dose-dependently, presumably by modifying the production of AAC(6')/APH(2"). The manifestation of ABK-resistant phenotype by Mixr-type MRSA required the coexistence of BLM. Therefore, ABK must be administered carefully to cure MRSA infection in patients who have been treated with BLM.

Acetyltransferases↗
PubMed1995

Quinolones.

Explore the source record for details and available documents.

Bacteria↗
PubMedDate not supplied

Cefepime.

Cefepime is a potent, broad-spectrum, fourth-generation cephalosporin with enhanced activity against most gram-positive aerobic bacterial pathogens and many gram-negative aerobic bacteria that are resistant to other cephalosporins. The drug's zwitterionic structure contributes to more rapid penetration of gram-negative bacterial cell membranes, and its low affinity for most type I beta-lactamases leads to significantly reduced enzymatic degradation compared with other cephalosporins. Cefepime has a good toxicity profile, with minor gastrointestinal and central nervous system symptoms being most prevalent. At dosages ranging from 1-2 g every 8-12 hours, it is an alternative option for infections of the lower respiratory tract, urinary tract, and skin and skin structures, as well as febrile episodes in neutropenic patients with cancer, and bacteremia or septicemia in critically ill patients.

Anti-Bacterial Agents↗
PubMed1976

Current drug therapy--cephalosporins.

The following aspects of cephalosporins are reviewed: chemistry and stability; mechanism of action; spectrum of activity; resistance; absorption, distribution, metabolism and excretion; uses; cautions; drug interactions; laboratory test interferences; and dosage.

Cephalosporins↗
PubMed1993

Quinolone therapy in intensive care unit settings.

Three fluoroquinolone antimicrobials (norfloxacin, ciprofloxacin, and ofloxacin) could be used to prevent or treat infections in intensive care unit patients. All of these fluoroquinolones are particularly active against Gram-negative, aerobic bacteria. However, the pharmacokinetic properties of each fluoroquinolone are unique. Furthermore, only ciprofloxacin and ofloxacin are available for intravenous administration. Based on current, available information: a) fluoroquinolones are not endorsed for inclusion in selective decontamination protocols; b) fluoroquinolones are endorsed for empiric therapy of suspected Gram-negative bacterial infections based on local microorganism susceptibility patterns; and c) fluoroquinolones are endorsed for treatment of microbiologically documented infections based on their distribution properties, low rate of toxicity, and rapid bactericidal effect.

Administration, Oral↗
PubMedDate not supplied

Antibiotic use and antibiotic resistance in the intensive care unit: are we curing or creating disease?

Antibiotics represent one of the most commonly prescribed medical therapies for hospitalized patients. The practice of "spiralling empiricism" has increasingly led to the unnecessary administration of antibiotics, resulting in the emergence of infections with antibiotic-resistant bacteria that are associated with increased rates of patient mortality. Ventilator-associated pneumonia due to antibiotic-resistant bacteria has become recognized as an important problem resulting from prior antibiotic exposure. Health professionals must be aware of this problem and avoid the unnecessary administration of these drugs. Future research efforts should be aimed at improving our ability to diagnose and exclude infections and to develop better strategies for antibiotic administration in the intensive care unit setting.

Anti-Bacterial Agents↗
PubMed1975

[Action of decamethoxin on diphtherial exotoxin].

The results of the study of the detoxicating effect of decamethoxin on diphtheria toxin are presented. It was noted that decamethoxin in subbacteriostatic concentrations inhibited the process of the toxin production in Corynebacteria diphtheriae. The detoxicating effect of the drug was clearly evident when used in a concentration of 10gamma/ml at a 2-hour exposure. Decamethoxin in a dose of 0.1 gamma/ml neutralized the effect of the diphtheria toxin on contact for 24 hours.

Animals↗
PubMed1994

[Factors on antimicrobials].

Infections which are difficult to cure are mainly caused by resistant organisms or opportunistic pathogens. For the treatment of such infections, we should maximize drug's therapeutic potentials, and minimize its toxicity. Characteristics of pharmacodynamics and pharmacokinetics in antimicrobials should be taken into account to maximize the efficacy and to minimize the toxicity. Bactericidal activity and post-antibiotic effect of antimicrobials are the major factors to determine the optimal dosing. Infections caused by intra-phagocytic pathogens should be treated with drugs which penetrate cell well. Early treatment with antimicrobials is the corner-stone for the treatment of infections in immunocompromised host. It is very important to determine which of the two drugs should be given first to maximize the efficacy on combination therapy.

Anti-Bacterial Agents↗