Pseudomonas aeruginosa
Introduction
Pseudomonas aeruginosa is a common Gram-negative, rod-shaped bacterium that can cause disease in plants, animals, and humans. It is a multidrug-resistant pathogen recognized for its ubiquity, its intrinsically advanced antibiotic resistance mechanisms, and its association with serious illnesses – particularly hospital-acquired infections such as ventilator-associated pneumonia and various sepsis syndromes.
Morphology and Classification
Pseudomonas aeruginosa is a member of the Pseudomonas genus, a diverse group of bacteria found in a wide variety of environments. The bacterium is rod-shaped and possesses a single flagellum, which allows for motility. It is also a Gram-negative bacterium, characterized by its resistance to multiple types of antibiotics due to the presence of an outer membrane that prevents the entry of these drugs.
Genetics
The genome of Pseudomonas aeruginosa is relatively large compared to other bacteria, consisting of a single circular chromosome that contains approximately 6.3 million base pairs. This large genome allows the bacterium to adapt to a wide variety of environments and resist many different types of antibiotics. The genome also contains numerous gene clusters that are involved in the production of secondary metabolites, which can contribute to the bacterium's pathogenicity.
Pathogenicity and Clinical Significance
Pseudomonas aeruginosa is an opportunistic pathogen, meaning it primarily infects individuals who have a compromised immune system. It is a leading cause of hospital-acquired infections, particularly in patients who are critically ill or have a weakened immune system. The bacterium can cause a variety of infections, including pneumonia, bloodstream infections, urinary tract infections, and surgical site infections. It is also a significant cause of infections in patients with cystic fibrosis, where it can lead to a decline in lung function.
Antibiotic Resistance
Pseudomonas aeruginosa is known for its intrinsic resistance to many antibiotics, including penicillins, cephalosporins, and aminoglycosides. This resistance is primarily due to the presence of an outer membrane that prevents the entry of these drugs, as well as the production of efflux pumps that can pump out these drugs if they do manage to enter the cell. The bacterium can also acquire resistance to other antibiotics through the acquisition of resistance genes via horizontal gene transfer.
Treatment and Prevention
The treatment of infections caused by Pseudomonas aeruginosa can be challenging due to the bacterium's resistance to many antibiotics. However, some antibiotics, such as piperacillin-tazobactam, ceftazidime, and ciprofloxacin, can still be effective against this bacterium. In addition to antibiotic therapy, management of infections also involves supportive care and, in some cases, surgical intervention. Prevention of infections involves adherence to infection control practices in healthcare settings, such as hand hygiene and the use of sterile techniques during invasive procedures.