Role of Acanthamoeba in urinary tract infections

Urinary Tract Infection (UTI) is the second most common healthcare associated infections (HCAI) in England. The HCAI prevalence survey data (2011) released by the Health Protection Agency (HPA) shows that UTI’s are the second most common HCAI accounting for 17.2% of the total HCAI’s in England. Escherichia coli, Klebsiella and Proteus are Gram negative bacteria frequently associated with UTI's. More HCAI's are related to the use of urinary catheters than any other medical device. An estimated 450,000 people in the UK use catheters on a long-term basis. Uropathogens are known to form biofilms on catheters causing recurrent infections. Biofilms are difficult to eradicate due to decreased antibiotic susceptibility and increased resistance. A recent study has found the presence of Acanthamoeba in urine of critically ill patients. The ubiquitous protozoan Acanthamoeba, is an opportunistic pathogen well recognised to serve as a reservoir for prokaryotes. Our recent findings (unpublished) confirm that the above mentioned bacteria can invade, survive and multiply within Acanthamoeba evading host defence and antibiotic action by forming cysts. It is our intention to investigate the presence of Acanthamoeba in urine samples collected from patients

A novel antimicrobial urinary catheter

Urinary tract infections (UTI) are one of the most common healthcare associated infections (HCAI) accounting for 17.2% of the total HCAI’s in England, out of which 43% of infections were associated with the use of an indwelling catheter. Catheter associated UTI (CAUTI) caused by uropathogenic biofilm formation is responsible for prolonged hospital admissions, increased costs and significant morbidity. The NHS routinely uses silver alloy-coated latex catheters and silicone catheters impregnated with nitrofurazone to prevent CAUTIs. However, numerous studies have questioned their antimicrobial efficacy. This raises the urgent need to develop novel catheters that can inhibit bacterial colonization. The present study provides the in vitro evidence to support the use of novel Cetylpyridinium chloride (CPC) impregnated catheters in preventing biofilm formation. CPC impregnated catheters were prepared using a 3-step medical implant impregnation process. A biofilm microtitre plate assay was used to evaluate the antimicrobial effect of CPC, and the efficacy of impregnated catheters was assessed using an in vitro biofilm catheter colonization model. Non-impregnated catheters were used as control. Growth of Proteus mirabilis and extended spectrum beta lactamase (ESBL) positive and negative strains of Escherichia coli and Klebsiella was completely inhibited by CPC (30 μg/ml) after 24h of incubation in artificial urine medium. The novel CPC impregnated catheters were highly efficacious in inhibiting biofilm colonization of all uropathogens tested at all time intervals. Taken together, our preliminary results provide promising evidence for the potential application of CPC impregnated catheters in preventing CAUTI

The role of Acanthamoeba in recurrent urinary tract infections

Urinary Tract Infections (UTI) are clinically important in the current health scenario due to emerging antibiotic resistance and increasing recurrence levels. In the UK nearly half of all women have had at least one episode of UTI in their life time while one in every 2000 men develop the infection each year (Urinary Tract Infections – Adults, 2012). In infants and children, UTI is the most common bacterial infection (NICE, 2007). A variety of pathogens are known to cause UTI. According to Davis and Flood (2011) E. coli is the causative agent of UTI in about 80% of community acquired and 50% of hospital acquired UTI. In a UK wide multicentre study conducted by Farrell et al (2003), E. coli was found to be the predominant pathogen isolated from patients suffering from UTI followed by Enterococcus faecalis, Klebsiella pneumonia and Proteus mirabilis. Over the years a variety of bacteria have developed different tactics to survive encystment, resist phagocytosis and multiply within Acanthamoeba, which is a free-living amoeba. The intracellular settings of Acanthamoeba protect the bacterial endosymbionts from adverse conditions such as the human immune response (Lovieno et al, 2010). Santos et all (2009) conducted a study based on the hypothesis that urinary pathogenic bacteria can potentially use Acanthamoeba as a protective tool to survive antimicrobial effect, disinfection and the host immune response. They evaluated 63 urine samples collected from indwelling catheters of critically ill patients. In an interesting finding, 23% of these samples tested positive for the presence of Acanthamoeba spp. Although this study had few limitations, it definitely paved the way for more research into the role of Acanthamoeba in HCAI, particularly human UTI