Short communicationEffects of subinhibitory concentrations of amikacin and ciprofloxacin on the hydrophobicity and adherence to epithelial cells of uropathogenic Escherichia coli strains
Introduction
The surface hydrophobicity of bacteria is one of the non-specific factors contributing to their adherence. The hydrophobic properties of bacteria are responsible for formation of biofilm and adhesion to epithelial cells. The hydrophobicity of many Gram-negative rods and Gram-positive bacteria has been described [1], [2], [3], [4], [5], [6].
Bacterial adherence to the epithelial surface is considered as one of the important factors in the infection process. Adherence is an interaction between adhesin molecules on the bacterial cell surface and complementary receptor molecules on the host cell surface. Microorganisms adhere to epithelial cells in a highly selective manner and thus cannot be removed by unspecific defence mechanisms of the urinary, respiratory, gastrointestinal and genital tracts [3], [7].
The effective therapeutic result of antibiotics is best when the concentration is above the minimal inhibitory concentration (MIC) between consecutive doses. Looking at the pharmacokinetic curves of antibiotics, it can be seen that their concentrations exceed the MIC for only a certain period of time, after which they become lower than the MIC and are called subinhibitory concentrations (sub-MICs), especially in tissues, i.e. the sites of infections where antibiotic concentrations are frequently lower than those in blood, e.g. abscesses or chronic osteomyelitis [8]. Sub-MICs of antibiotics cannot kill bacteria but they have been shown in vitro to affect microorganisms in various ways, e.g. through suppression of bacterial growth, induction of morphological changes in bacteria, alteration of the cell surface structure, inhibition of enzyme and toxin production and suppression of bacterial adhesion to host cells [3], [4], [5], [9], [10].
The aim of this study was to evaluate the hydrophobic character of uropathogenic Escherichia coli strains and to study changes in bacterial surface hydrophobicity and adhesion to uroepithelial cells following treatment with amikacin and ciprofloxacin at sub-MICs.
Section snippets
Bacterial strains
Sixty-six E. coli strains isolated from urine of patients with cystitis were studied.
Antibiotics
Amikacin (Biodacyna, Warsaw, Poland) and ciprofloxacin (Proxacin, Warsaw, Poland) were used.
Determination of the MIC
The microdilution broth method using Mueller–Hinton broth enriched with 25 mg/L CaCl2 and 12.5 mg/L MgSO4 (pH 7.4) with serial dilution of the antibiotics was used. MICs of amikacin were in the range 0.5–8.0 μg/mL and those of ciprofloxacin were 0.007–0.031 μg/mL.
Bacterial hydrophobicity
The surface hydrophobicity of bacterial cells treated with
Results
In preliminary studies, we determined the adherence capacity of E. coli strains to epithelial cells. E. coli strains could be divided into four groups (Table 1). In Group I, the mean number of bacteria per epithelial cell was 0–17. There were 38 strains in this group (22 with a hydrophobic surface and 16 with a hydrophilic surface). Group II, in which the mean number of bacteria per epithelial cell was 18–24, included eight strains, only one of which had a hydrophilic surface. All strains
Discussion
The data presented in this paper confirm and extend the previous observation that certain antibiotics at subinhibitory concentrations reduce bacterial hydrophobicity and adhesion. These effects are not limited to E. coli strains, but also occur with many different bacteria [1], [2], [3], [4], [5], [6]. Several researchers have reported that sub-MICs of some antibiotics increase the surface hydrophobicity and the ability of bacteria to adhere to epithelial cells [13], [14].
Because ciprofloxacin
References (17)
- et al.
Effect of subminimal inhibitory concentrations of three fluoroquinolones on adherence of uropathogenic strains of Escherichia coli
Int J Antimicrob Agents
(2002) - et al.
Gemifloxacin: effects of sub-inhibitory concentrations on various factors affecting bacterial virulence
Int J Antimicrob Agents
(2003) - et al.
Rifampicin sub-inhibitory concentrations reduce the expression of haemolysin in Aeromonas spp
Int J Antimicrob Agents
(2000) - et al.
Adherence of bacteria to hydrocarbons: a simple method for measuring cell-surface hydrophobicity
FEMS Microbiol Lett
(1980) - et al.
Effects of subinhibitory concentrations of ciprofloxacin on enterotoxigenic Escherichia coli virulence factors
J Chemother
(2000) - et al.
Effect of subinhibitory levels of aminoglycosides and fluoroquinolones on hydrophobicity and motility of Serratia marcescens
Epidemiol Mikrobiol Imunol
(2001) - et al.
Effect of subinhibitory concentration of piperacillin/tazobactam on Pseudomonas aeruginosa
J Med Microbiol
(2004) - et al.
Effects of growth in the presence of subinhibitory concentrations of dicloxacillin on Staphylococcus epidermidis and Staphylococcus haemolyticus biofilms
Appl Environ Microbiol
(2005)
Cited by (44)
Inhibition of biofilm formation and quorum sensing mediated virulence in Pseudomonas aeruginosa by marine sponge symbiont Brevibacterium casei strain Alu 1
2021, Microbial PathogenesisCitation Excerpt :The hydrophobicity of bacterial pathogens contributes to their adherence, which is responsible for biofilm formation and adhesion to epithelial cells. The adherence of bacterial cells to the epithelial surface is considered to be an important factor in the development of infection [63]. Our findings revealed that the level hydrophobicity index in B. casei CFCS treated PAO1 was 54.98 and 49.23% at 1% and 2% (v/v) concentrations, respectively and the level hydrophobicity index of untreated control is 68% (Fig. 3C).
Influence of Melaleuca alternifolia oil nanoparticles on aspects of Pseudomonas aeruginosa biofilm
2016, Microbial PathogenesisCitation Excerpt :The bacterial adhesin and your hydrophobic surface are the responsible properties by adhesion and preserving the bacterial-host contact during the primary stage of infection. A change in this hydrophobic surface of cell, may damage the development of in vivo infection, and could make the bacteria, more sensitive to the treatment [40]. The adhesion test to buccal epithelial cells left no doubt that the compounds decreased the adhesion of bacteria on two tested concentrations, these results lead us to suppose that the decrease of biofilm formation and adhesion P. aeruginosa PAO1 may be due the other factors, such specific process (intermediated by pilus, fimbriae and adhesins) [41,42].
Luteolin decreases the attachment, invasion and cytotoxicity of UPEC in bladder epithelial cells and inhibits UPEC biofilm formation
2014, Food and Chemical ToxicologyIn vitro effect of antibiotics on biofilm formation by Bacteroides fragilis group strains isolated from intestinal microbiota of dogs and their antimicrobial susceptibility
2014, AnaerobeCitation Excerpt :Microorganisms often grow in the presence of sub-MICs, which although not able to inactivate microorganisms are potentially capable of altering the chemical and physical cell-surface characteristics and consequently the functionality and expression of some virulence properties such as adhesion, biofilm formation, hydrophobicity and motility [19]. Most studies on the effects of sub-MICs of antibiotics have focused largely on Escherichia coli and Pseudomonas aeruginosa [20,19] and to the best of our knowledge, there is little information in the literature concerning B. fragilis. Imipenem showed a very good effect on biofilm reduction and clindamycin showed approximately 50% inhibition of biofilm formation.
Effects of sub-minimum inhibitory concentrations of ciprofloxacin on biofilm formation and virulence factors of Escherichia coli
2019, Brazilian Journal of Infectious Diseases