Abstract
Two hundred fifty mid-stream urine specimens were collected from Baqubah Teaching Hospital and Al-Batool Teaching Hospital from patients with urinary tract infections (UTI). Of these investigated urine specimens, 66 (26.4%) specimens showed positive growth culture of Gram-negative bacteria. From these, Escherichia coli was the most prevalent bacteria of the examined culture (41, 62.12%). Additionally, the cup assay was used to determine colicin producers while the most efficient colicin producers were estimated by the formation of larger inhibition zone. Approximately half of the investigated E. coli isolates (20, 49 %) was colicin producers. Colicins was extracted after induction by mitomycin-C showed a concentration of 3020 μg/ml, as estimated utilizing the Lowry method, while its activity was 80 U/ml. Our study results showed that colicin had significant antibiofilm activity (P≤ 0.05) against Candida albicans and the effect seemed to be concentration dependent. . However, the values of biofilm inhibition varied depending on the different tested isolates. The biofilm of isolate 5 showed the most significant inhibition (P≤ 0.05) by colicin with a value of 46%, while isolate 3 was less affected with an inhibition rate of 19% at the concentration of 2500 μl/ml.
Highlights
Escherichia coli is one of the most common pathogens, which causes a wide spectrum of diseases within and outside the intestinal tract]1[
It is believed that the killing mechanism of colicins produced by E. coli can be accomplished by pore formation in the inner membrane of the target cell and degradation of intracellular components such as DNA and RNA ]7[
The medium and the unbound cells were removed; the wells were washed by Phosphate Buffer Saline (PBS) left to dry for 15 mins. 200 μl of Crystal Violet (CV) were added to the wells and left for 20 mins
Summary
Escherichia coli is one of the most common pathogens, which causes a wide spectrum of diseases within and outside the intestinal tract]1[. Bacteriocins are ribosomal synthesized antimicrobial peptides that have the ability to kill or inhibit the growth of other strains, without damaging the producing bacteria due to having specific immunity proteins ]4[. C. albicans isolates detection was confirmed by forming germ tubes ]15[ and by Vitek-2 system. The medium and the unbound cells were removed; the wells were washed by Phosphate Buffer Saline (PBS) left to dry for 15 mins. The suspensions of C. albicans were inoculated to 96- flat well microtiter plates previously inoculated with colicin at Minimum Inhibitory Concentration (MIC) concentrations. 200 μl of acetone: ethanol solution (20:80) was added to the wells and left for 20 min, the result was read by the plate reader ]21, 22[. Biofilm inhibition was calculated using the below equation ]23[: Inhibition of biofilm formation%=
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