Pseudomonas Aeruginosa Case Study

Pseudomonas aeruginosa is one of the most common hospital associated pathogens found around the world that accounts for a large spectrum of infections. Being an opportunistic bacterium, P. aeruginosa is rarely a cause of concern in most individuals, however in the vulnerable, it can bring about life threatening illnesses. These infections are often difficult to cure as a result of this pathogens phenomenal intrinsic resistance as well as its ability to acquire resistance easily to many antibiotics. The ineffectiveness of such antibiotics in addition to the lack of novel antibiotics makes P. aeruginosa a grave threat worldwide [Maitrayee].

Classed as a gram negative bacteria, P. aeruginosa can be present in most environments which is a result aeruginosa can cause a variety of infections (Table 1) that range from eye infections such as keratitis to gastrointestinal tract infections like necrotising enterocolitis [Mesaros]. Approximately 10% of all nosocomial infections worldwide are produced by this bacterium which has the ability to kill humans within 24 hours of infection [maitrayee +action]. In the UK, Pseudomonas is thought to be the cause of an estimated 10,000 cases of hospital acquired infections per year as well as being the second most common gram negative bacteria in this setting (Figure 1) [action + cdc]. Individuals that are susceptible to P. aeruginosa infections include: those admitted in intensive care units, those that have a weakened immune system such as cancer patients, and those with underlying illnesses like cystic fibrosis. As a result, infections in these patient groups are severe, with association to high morbidity and mortality maitrayee]. In patients with cystic fibrosis, P. aeruginosa can be lethal with infections by this bacteria being a leading cause of death. In addition, statistics also show that this bacterium can be present in the lungs of 80% of cystic fibrosis patients aeruginosa consists of 5567 genes which is significantly greater than other similar bacteria like E. coli. This massive genome equips P. aeruginosa with high versatility as well as resistance genes that provides intrinsic resistance to many antibiotics. The natural resistance of this bacterium is multifactorial but includes mechanisms such as the expression of efflux pumps and beta-lactamases as well as the limited accessibility of its outer membrane. Moreover, P. aeruginosa can readily acquire resistance by horizontal gene transfer from other organisms and via chromosomal mutations. These resistance mechanisms can also be simultaneously expressed resulting in multidrug resistance [Lambert]. The production of biofilms is another factor that makes this bacterium so problematic. This matrix consisting of multiple cells surrounded by extracellular polysaccharides can protect this bacterium from the hosts immune system as well as contributing to antibiotic resistance. Therefore, biofilms can make P. aeruginosa even more difficult to eradicate