Novel surface biochemical modifications of urinary catheters to prevent catheter-associated urinary tract infections

More than 70% of hospital-acquired urinary tract infections are related to urinary catheters, which are commonly used for the treatment of about 20% of hospitalized patients. Urinary catheters are used to drain the bladder if there is an obstruction in the tube that carries urine out of the bladder (urethra). During catheter-associated urinary tract infections, microorganisms rise up in the urinary tract and reach the bladder, and cause infections. Various materials are used to fabricate urinary catheters such as silicone, polyurethane, and latex. These materials allow bacteria and fungi to develop colonies on their inner and outer surfaces, leading to bacteriuria or other infections. Urinary catheters could be modified to exert antibacterial and antifungal effects. Although so many research have been conducted over the past years on the fabrication of antibacterial and antifouling catheters, an ideal catheter needs to be developed for long-term catheterization of more than a month. In this review, we are going to introduce the recent advances in fabricating antibacterial materials to prevent catheter-associated urinary tract infections, such as nanoparticles, antibiotics, chemical compounds, antimicrobial peptides, bacteriophages, and plant extracts.

Investigating the antibacterial effects of some Lactobacillus, Bifidobacterium and acetobacter strains killed by different methods on Streptococcus mutans and Escherichia coli

Although there are many health advantages assigned to different live bacteria such as probiotics, some health threatening effects have also been reported. For example, live bacteria can transfer antibiotic resistance genes to other commensal and opportunistic bacteria of gastrointestinal tract. Recently, it was shown that using killed bacteria have some advantages over live ones. In this research, heat, paraformaldehyde and ozone killing methods were used to kill the bacteria. Acetobacter cerevisiae, Lactobacillus acidophilus, Bifidobacterium lactis and traditional vinegar and fermented dairy product (Kumeh) derived bacteria were killed and their antibacterial activity against Streptococcus mutans and Escherichia coli was investigated. To identify the bacteria isolated from the traditional products, 16S rDNA gene was partially sequenced. The gene analysis showed vinegar and Kumeh derived bacteria were Acetobacter pasteurianus and Lactobacillus crustorum (LcK) strains respectively. The S. mutans growth inhibition was detected in the all concentrations of all killed samples. However, generally, E. coli showed more resistant to the killed bacteria than S. mutans and the antibacterial effect of heat-killed bacteria against E. coli was not observed in the all concentrations for some killed bacteria. Among the pathogenic bacteria, S. mutans was the most sensitive one to the killed bacteria with 70% of reduction in its viability. In conclusion, this research showed that different killed bacteria had different effects on other bacteria and the killing method showed an impact on these effects. Overall, paraformaldehyde-killed L.crustorum (LcK) showed the best antibacterial activity against S. mutans; about 70% decrease in bacterial viability.