The host is the main environment for bacteria, and they also expose to many antibiotics during the treatment of infectious diseases in host body. In this study, it was aimed to investigate possible changes in growth rate and expression levels of three virulence genes (foc/foc, cnf1, and usp) in a uropathogenic E. coli standard strain within the presence of ciprofloxacin, nitrofurantoin, and trimethoprim-sulfamethoxazole. The UPEC C7 strain was grown on tryptic soy broth-TSB (control), TSB + ciprofloxacin, TSB + nitrofurantoin, and TSB + trimethoprim-sulfamethoxazole for determination of both growth rate and gene expression level. Antibiotics were added according to their sub-minimal inhibition concentrations. E-test was used to determine MIC values of antibiotics. Growth changes were measured in absorbance 600 nm during 24-h period. Total RNA isolations were performed after incubation for 24 h at 37 °C. Gene expression levels were determined by quantitative PCR. Tukey's post hoc test was used for statistical analysis. According to absorbance values, it has been shown that only ciprofloxacin and trimethoprim-sulfamethoxazole have lead significant decrease on growth rate. We also detected statistically significant differences in each gene expression levels for all antibiotics via relative quantification analysis. Fold changes in gene expression was found 0.65, 1.42, 0.23 for foc/foc gene; 0.01, 0.01, 2.84 for cnf1 gene; and 0.1, 0.01, 0.01 for usp gene in the presence of ciprofloxacin, nitrofurantoin, and trimethoprim/sulfamethoxazole, respectively. This investigation has shown that antibiotics can play a role as an environmental factor which may determine the pathogenicity of bacteria in vivo.
Pseudomonas aeruginosa and Staphylococcus aureus are known as important nosocomial infectious agents also their co-infections are commonly seen in some patient groups. It is well known that host factors such as hormones have roles in modulation of growth, pathogenesis and susceptibilities to antimicrobials. In our study, the influences of norepinephrine (NE) and melatonin (MEL) on antibiotic susceptibilities were examined in mono and co-culture conditions. Methicilin resistant Staphylococcus aureus (MRSA) ATCC 43300 and Pseudomonas aeruginosa ATCC 27853 were investigated to determine the minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of ciprofloxacin and gentamicin in the absence/presence of NE (0.0017 and 0.04μg/mL) and MEL (6 and 60 pg/mL) by microdilution method in mono and co-culture. It was found that hormones decreased (among 2-64 fold) MIC and MBC values of both antibiotics for MRSA. However, it was shown that hormones had no effect on MIC values of both antibiotics for P. aeruginosa. MIC and MBC values of both antibiotics for co-culture were found to be reduced compared to monoculture of MRSA; were found to be increased compared to monoculture of P. aeruginosa. Whereas, hormones decreased MIC values of both antibiotics in co-culture conditions. Our results suggest that both hormones decreased MIC values and it seems that hormones could influence antibiotic susceptibilities in a strain-dependent manner.
Mammalian hormones are shown to affect not only regulation of mammalian homeostasis but also play roles in cross-talk between microorganisms and their hosts. In our study, the roles of norepinephrine (NE) at two different concentrations on growth alterations, adhesion - invasion of Pseudomonas aeruginosa were investigated.
The effects of NE on the growth, adhesion - invasion of P. aeruginosa ATTC 27853 were examined in human lung carcinoma (A549) cell culture. We analysed two concentrations (HNE: 0.04μg/mL and LNE: 0.0017 μg/mL) of NE considering NE’s psychological levels in a healthy individual to imitate in vivo conditions of the host. Bacterial counts of growth and adhesion-invasion were examined by the colony counting method. Growth of bacterium was significantly reduced in the presence of NE at 90’ incubation (p: 0.0004 for high concentration and p: 0.0003 for low concentration); on the other hand, at 180’ minutes incubation, only low concentration reduced the growth (p˂0.0001). While adhesion was increased in the presence of low NE concentration (p: 0.013), there was no alteration in invasion of P. aeruginosa in the presence of NE (p˃0.05). Our results suggested that NE has different effects on the growth and adhesion of P. aeruginosa and these effects depend on concentration and incubation period.
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