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PubMed1977

A review of the medical considerations of the use of tylosin and other macrolide antibiotics as additives in animal feeds.

The use of antibiotics in animal feeds is reviewed with special reference to possible problems which might be encountered in human medicine. Emphasis is placed on the macrolide antibiotics, especially tylosin. Even though there can be cross-resistance between tylosin and erythromycin, the increasing use of tylosin in animal feeds has not caused an increase of resistance to erythromycin in human isolates of Staphylococcus aureus. There is no significant evidence that tylosin resistant staphylococci of animal origin have endangered human health. Tylosin is not effective against the gram-negative intestinal flora, which thus does not lead to selection of R-factors by conjugation. From the human medical stand point, there is no reason that precludes the use of tylosin as a fee additive in animal feeds.

Animal Feed↗
PubMedDate not supplied

In vitro activity of ceftazidime in combination with other antibiotics.

189 bacterial strains were investigated for their in vitro sensitivity against ceftazidime (alone and in combination with another antibiotic). Moreover, the possibility to prevent development of secondary bacterial resistance as observed in subcultures at subinhibitory antibiotic concentrations, was studied using specific antibiotic combinations. Of 115 staphylococcal strains (91 strains of Staphylococcus aureus, 24 strains of Staphylococcus epidermidis), 2% were sensitive, 82% were moderately sensitive and 16% were resistant to ceftazidime. On combining ceftazidime with vancomycin, synergism was found in 61% of the strains, and secondary resistance to ceftazidime could be prevented with this combination. The combination of ceftazidime and clindamycin showed synergism in 26% and an additive effect in 48% of the strains. Secondary resistance to ceftazidime did not develop with this combination in subcultures at subinhibitory concentrations in which loss of activity was only minimal with clindamycin alone. Rifampicin and fusidic acid were highly active against staphylococci. In combination with ceftazidime, only weak synergism or additive effects were seen in most strains; no antagonism could be observed. In subcultures at subinhibitory concentrations, secondary resistance to rifampicin and fusidic acid developed rapidly and could be partially prevented by adding ceftazidime. Of 60 Pseudomonas aeruginosa strains, 84% were sensitive, 13% were moderately sensitive and 2% were resistant to ceftazidime. Synergism was most frequently observed when ceftazidime was combined with tobramycin. Using this combination, secondary resistance of Pseudomonas strains to ceftazidime did not develop. When ceftazidime was combined with piperacillin, synergism was observed in most strains, but the development of secondary resistance in vitro was not prevented.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Bacterial Agents↗
PubMed1992

Prevention of viridans-group streptococcal septicemia in oncohematologic patients: a controlled comparative study on the effect of penicillin G and cotrimoxazole.

In a controlled randomized study among 48 patients undergoing 75 courses of aggressive antileukemic therapy, it was shown that cotrimoxazole was less effective than penicillin G in preventing septicemia due to viridans streptococci. Both antibiotics were given intravenously. During 35 episodes of chemotherapy in the group of patients on penicillin G only, one patient developed a streptococcal bacteremia; this contrasted with bacteremia and septicemia in seven patients during 40 episodes in the group on cotrimoxazole. In three of these seven patients, septicemia was associated with respiratory failure and it was the cause of death in one. Both aerobic gram-negative rods and streptococci which caused infection despite cotrimoxazole prophylaxis were resistant to cotrimoxazole. Side effects such as hypersensitivity and favorable or unfavorable interaction with the oral selective decontamination regimen were similar for the two drugs, with the exception of colonization with Candida spp, which occurred more often in patients on cotrimoxazole than in patients on penicillin.

Agranulocytosis↗
PubMed1989

Dactimicin, a new aminoglycoside: in vitro activity, post-antibiotic effect and interaction with other antibiotics.

The in vitro activity of the new aminoglycoside dactimicin in comparison to amikacin was tested alone and in combination with piperacillin, mezlocillin and ceftazidime against freshly isolated clinical pathogens. Dactimicin was more active than amikacin against Enterobacter cloacae, Providencia rettgeri and Salmonella spp., and less active than amikacin against Escherichia coli, Pseudomonas aeruginosa and Acinetobacter anitratus. Using the checkerboard technique, the combination of either dactimicin or amikacin with the other drugs was shown to result in synergistic interaction against most of the 23 strains tested. Dactimicin-ceftazidime and amikacin-ceftazidime were the most effective combinations, demonstrating synergism against 91% and 95% of the isolates respectively. Antagonism was not encountered. Using the time-kill method, synergism was seen in most cases, indifference rarely being seen; antagonism was not observed. Dactimicin induced a post-antibiotic effect which ranged from 1 h for Enterobacter cloacae to 2.4 h for Escherichia coli. An average post-antibiotic effect of 0.6 h was also seen when dactimicin was combined with piperacillin, mezlocillin and ceftazidime. The findings indicate that dactimicin compares favorably in vitro with amikacin and suggest that clinical trials with this drug alone or in combination are warranted.

Acinetobacter↗
PubMed1989

Quinolone antimicrobial agents: adverse effects and bacterial resistance.

Adverse effects, drug-drug interactions and bacterial resistance to the new quinolone antimicrobial agents are reviewed. Clinical adverse effects are reported to occur in 5-10% of patients, and include primarily gastrointestinal disturbances, central nervous system toxicity and rash. Laboratory abnormalities are reported to occur in 5-12% of patients, and include mild reversible elevations of transaminases. Quinolones are not recommended in persons whose bone growth is incomplete or in pregnant or nursing women because cartilage toxicity has been observed in juvenile beagles. Drug-drug interactions may occur between quinolones and theophylline, caffeine, and magnesium- or aluminium-containing compounds such as antacids and sucralfate. Bacterial resistance occurs by chromosomal mutations which alter the target enzyme DNA gyrase or decrease drug accumulation. Emergence of resistance during therapy is uncommon to date but can be problematic in infections with Pseudomonas aeruginosa. Staphylococcus aureus and other bacteria for which the therapeutic index may be low. In summary, quinolones thus far have been well tolerated, but more experience is needed to determine the exact nature and extent of adverse effects and emergence of bacterial resistance.

4-Quinolones↗
PubMed1986

Fluorinated quinolones. A review of their mode of action, antimicrobial activity, pharmacokinetics and clinical efficacy.

Quinolones, chemically related to nalidixic acid, have a strong and rapid bactericidal action against Gram-negative bacteria, including Ps. aeruginosa, some Mycobacteria, Legionella and Staphylococci. Streptococci and anaerobic bacteria are usually less sensitive. The quinolones exert their bactericidal action through inhibition of the enzyme DNA gyrase. Quinolones are absorbed for 50-100% from the gastro-intestinal tract, their volume of distribution is generally high (2 l/kg) and high concentrations are reached in almost all organs. The elimination half-lives range from 4 to 14 h. The efficacy of quinolones in urinary tract infections has been shown in many studies. They also seem to be effective in many serious infections. In animal studies their efficacy was generally equal or superior to aminoglycosides. Until now only mild and infrequent side effects have been reported.

Animals↗
PubMed1985

In vitro activity of enoxacin compared with norfloxacin and amikacin.

The in vitro activity of enoxacin was tested against 1000 clinical isolates of gram-positive and gram-negative microorganisms and compared with that of norfloxacin and amikacin. The MIC90 of enoxacin was 1 mg/l for Enterobacteriaceae, 2.6 mg/l for Pseudomonas aeruginosa and 6.2 mg/l or Staphylococcus aureus. The inoculum effect was minimal. The MICs and MBCs for Pseudomonas aeruginosa strains were significantly affected by the addition of calcium and magnesium ions. Synergy was occasionally observed between enoxacin and the antibiotics tested; antagonism was rare.

Amikacin↗
PubMed1989

In vitro activity of combinations of beta-lactam antibiotics with beta-lactamase inhibitors against cephalosporinase-producing bacteria.

Combinations of different beta-lactam antibiotics, including cefotaxime, with three beta-lactamase inhibitors were tested against cephalosporinase producing bacterial strains. The most significant antagonism was obtained with a combination of clavulanic acid and cefotaxime, while almost no antagonism was observed with sulbactam and tazobactam. In strains belonging to five different species there was a correlation between the levels of cephalosporinase produced after exposure to different concentrations of inhibitors and the MICs of cefotaxime combined with the same concentrations of inhibitors. It is concluded that there is little likelihood of antagonism between beta-lactam antibiotics and sulbactam or tazobactam.

Anti-Bacterial Agents↗
PubMedDate not supplied

Macrolide antibiotics.

This article is an extensive review of current information available on the macrolide antibiotics. This includes antimicrobial spectrum, pharmacology, complications and side effects, and pediatric use of these drugs. These are important antibiotics, but careful selection of patients must be made and the physician must be alert for evidence of drug-drug interactions, which are not uncommon with several members of this class.

Anti-Bacterial Agents↗
PubMed2001

[Fluoroquinolones: utilization in renal and urogenital tract infections].

The purpose of this review is to give an introduction in the class of fluoroquinolones, which has become a large class of substances, and to discuss the use, role, and place of these drugs in the treatment of urinary tract infections. The classification of the fluoroquinolones contains four groups. Antibacterial spectrum, pharmacokinetics, and indications are the main criteria. The various fluoroquinolones differ in their antibacterial spectrum, the antibacterial activity, and pharmacokinetic properties. Therefore selection, use, and dosage regime of the substances should be carried out under respective clinical requirements and medical points of view. The physician has to consider the specific indications for each substance in each individual case. Fluoroquinolones are suitable antibacterial agents for various urinary tract infections and are a valuable and useful addition to the antimicrobial treatment.

4-Quinolones↗
PubMed2006

[Recurrent urinary tract infections in women. Virulence of pathogens and host reaction].

The interactions of host-specific and microbial factors are responsible for recurrent urinary tract infections (rUTI). The anatomical properties of the female urogenital tract favor colonization by uropathogens. Local factors such as glucose concentration of the urine, stability of the lactobacilli population, the influence of estrogens, the activity of Tamm-Horsfall protein or of defensins, and disturbance of the systemic defense mechanisms dictate the course of an infection. The most prominent uropathogen is E. coli. It expresses various virulence factors including adhesions, toxins, iron uptake systems, and a capsule. It is still unclear if there are virulence factors characteristic for E. coli strains causing rUTI. The formation of intracellular reservoirs by invasion of uroepithelial cells by E. coli could be another, as yet little noticed cause for rUTI. Therefore, in cases of rUTI the application of intracellularly active antibiotics should be considered.

Animals↗
PubMed2005

B cell superantigens: a microbe's answer to innate-like B cells and natural antibodies.

Marginal zone B cells and B-1 cells have been termed innate-like B cells as they express limited repertoires that play special roles in immune defenses against common infections. These B cells are the sources of natural antibodies and are capable of highly accelerated clonal responses that help counter blood-borne infections. We have characterized a class of microbial product with highly adapted binding interactions with host immunoglobulins/B cell receptors (BCRs), which enable the targeting of large supra-clonal sets of B cells for activation-associated apoptotic death. In recent studies, we have shown that all B cells with V region-targeted BCRs are susceptible. However, compared to follicular B cells, in vivo exposure preferentially causes innate-like B cells to undergo induced death with subsequent long-lasting supra-clonal depletion and immune tolerance. Based on these properties, it is likely that B cell superantigens influence the pathogenesis of some common infections, but also may provide novel therapeutic opportunities to treat B cell neoplastic and autoimmune diseases.

Animals↗
PubMed2006

Biodegradation of phenanthrene, spatial distribution of bacterial populations and dioxygenase expression in the mycorrhizosphere of Lolium perenne inoculated with Glomus mosseae.

Interactions between the plant and its microbial communities in the rhizosphere control microbial polycyclic aromatic hydrocarbons (PAH) biodegradation processes. Arbuscular mycorrhizal (AM) fungi can influence plant survival and PAH degradation in polluted soil. This work was aimed at studying the contribution of the mycorrhizosphere to PAH biodegradation in the presence of ryegrass (Lolium perenne L., cv. Barclay) inoculated with Glomus mosseae (BEG 69) by taking into account the structure and activity of bacterial communities, PAH degrading culturable bacteria as a function of the distance from roots. Ryegrass was grown in compartmentalized systems designed to harvest successive sections of rhizosphere in lateral compartments polluted or not with phenanthrene (PHE). Colonization of roots by G. mosseae (BEG 69) modified the structure and density of bacterial populations in the mycorrhizosphere, compared to the rhizosphere of non-mycorrhizal plants. G. mosseae increased the density of culturable heterotrophic and PAH degrading bacteria beyond the immediate rhizosphere in the presence of PHE, and increased the density of PAH degraders in the absence of the pollutant. Biodegradation was not significantly increased in the mycorrhizosphere, compared to control non-mycorrhizal plants, where PHE biodegradation already reached 92% after 6 weeks. However, dioxygenase transcriptional activity was found to be higher in the immediate mycorrhizosphere in the presence of G. mosseae (BEG 69).

Bacteria↗
PubMed1992

Mechanism of action of foscarnet against viral polymerases.

Foscarnet is a pyrophosphate analogue with activity against herpesviruses, human immunodeficiency virus (HIV), and other RNA and DNA viruses. Foscarnet and its analogues achieve their antiviral effects via inhibition of viral polymerases, with such inhibition not being dependent on activation or phosphorylation of the compounds by viral or cellular proteins. Current evidence indicates that foscarnet interferes with exchange of pyrophosphate from deoxynucleoside triphosphate during viral replication by binding to a site on the herpesvirus DNA polymerase or HIV reverse transcriptase. Reviewed herein are basic findings regarding the mechanism of action and antiviral activity of foscarnet and the related compound phosphonoacetic acid (PAA), as well as findings regarding potential mechanisms of viral resistance and interactions with other antiviral agents.

Antiviral Agents↗
PubMed1995

Modulation of the anti-Candida activity of apo-lactoferrin by dietary sucrose and tunicamycin in vitro.

The sensitivity to apo-lactoferrin (apo-LF) of two oral isolates each of Candida albicans and C. krusei preincubated in either sucrose- or tunicamycin-supplemented media was investigated. Known apo-LF-sensitive isolates of both C. albicans and C. krusei demonstrated significantly increased resistance to apo-LF when preincubated in sucrose-supplemented media, but such preincubation had no effect on an apo-LF-resistant isolate of C. albicans, irrespective of the sugar concentration in the medium. Surprisingly, an apo-LF-resistant isolate of C. krusei demonstrated increased susceptibility to apo-LF when preincubated in sucrose. Further, when preincubated with tunicamycin, a chemical that interferes with candidal cell-wall formation, the susceptibility to apo-LF of the resistant isolates increased significantly. These results, when extrapolated in vivo, imply that dietary sucrose may diminish the anticandidal potency of salivary lactoferrin. However, the aberrant behaviour of a single isolate of C. krusei under these circumstances is possibly due to the different cell-wall structure of this yeast and needs to be further investigated.

Apoproteins↗