Our purpose was to study whether treatment of Escherichia coli with subinhibitory concentrations of either cefamandole or gentamicin could change bacterial susceptibility to the serum bactericidal effect and to the phagocytic and killing activity of the rat liver reticuloendothelial system. Bacteria were grown overnight with 1/5 or 1/10 of the MIC of each antibiotic. At one-fifth of the MIC, ce...

Antibiotics have either bactericidal or bacteriostatic activity. However, they also induce considerable gene expression in bacteria when used at subinhibitory concentrations (below the MIC). We found that lincomycin, which inhibits protein synthesis by binding to the ribosomes of Gram-positive bacteria, was effective for inducing the expression of genes involved in secondary metabolism in Strep...

OBJECTIVES The aim of this work was to study the effect of subinhibitory concentrations of penicillin, chloramphenicol and erythromycin on the mutation rate of Streptococcus pneumoniae. METHODS The mutation rate to rifampicin and optochin resistance was estimated using fluctuation analysis in three capsulated S. pneumoniae strains, cultured both with and without different subinhibitory antibi...

Although rapid emergence of antibiotic-resistant mutants of Chlamydia trachomatis occurs when the organism is grown in subinhibitory concentrations of rifampin, no such mutants could be demonstrated when the organism was propagated under the same conditions in subinhibitory levels of the related drug rifabutin.

Pseudomonas aeruginosa is an important nosocomial opportunistic human pathogen and a major cause of chronic lung infections in individuals with cystic fibrosis. Serious infections by this organism are often treated with a combination of aminoglycosides and semi-synthetic penicillins. Subinhibitory concentrations of antibiotics are now being recognized for their role in microbial persistence and...

Variables affecting the adherence of Gardnerella vaginalis to human vaginal epithelial cells were examined in vitro. Adherence depended on pH, with maximum attachment occurring between pH 5 and pH 6. Preincubation of the bacteria at 56 degrees C for 30 minutes and ultraviolet irradiation resulted in a noticeable decrease in adherence. In contrast, adherence was not altered by preincubating the ...

The data presented show the ability of subinhibitory concentrations of plant essential oils to influence the production of enterotoxins A and B and alpha-toxin by Staphylococcus aureus. Subinhibitory concentrations of the oils of bay, clove, cinnamon, nutmeg and thyme had no significant effect on the overall quantity of extracellular protein produced. Haemolysis due to alpha-toxin was significa...

It has long been known that certain antibiotics, at subinhibitory concentrations, differentially inhibit the synthesis of alpha-hemolysin and other staphylococcal virulence factors. In this report, we show that subinhibitory clindamycin (SBCL) eliminates production of nearly all exoproteins by Staphylococcus aureus but has virtually no effect on cytoplasmic proteins. The effect was abolished by...