Molecular and immunological study of Pseudomonas aeruginosa isolated from wound and burn infected patients in Baghdad government

Pseudomonas aeruginosa is an important bacterium that opportunistically infects individuals with weakened immune systems, especially those with severe burns, wound infections and similar conditions. It is known to be resistant to various drugs. These bacteria have a high degree of tolerance to unfavorable environmental conditions and can withstand a wide spectrum of temperatures. In addition to its natural resistance to various disinfectants and antibiotics, this organism has the capacity to acquire genes that confer resistance and other variants that increase the potential to cause disease and initiate infection as the bacterial population grows. Burns and wounds are defined as serious traumatic injuries to the skin that penetrate the integumentary system, weaken the immune system, prolong hospitalization and ultimately increase the likelihood of infection while in hospital. Burn and wound infections can lead to sepsis and death, often because of imprudent administration of systemic antibiotics. Interventions such as surgical debridement and skin grafting create ideal conditions for the establishment of multidrug-resistant Pseudomonas aeruginosa in the community. This has a significant impact on the limited treatment options. The pathogenicity of the bacterium is entirely dependent on virulence factors, which can be categorized into components associated with acute and chronic infection. Many studies have shown that certain virulence factors play an important role in Pseudomonas aeruginosa infections, especially in burn and wound infections. This study included 250 patients with burn and wound infections admitted to various hospitals in Baghdad, Iraq. In addition, a control group of 76 healthy individuals was also included for immunological control. Isolates were cultured and identified using blood and MacConkey agar as well as a series of biochemical tests. The VITEK-2 compact system was used to determine the confirmatory diagnosis and antibiotic resistance profile. The biofilm forming capacity of the isolates was tested by quantitative Microtiter plate technique. Conventional polymerase chain reaction was performed to identify all virulence genes. Enzyme-linked immunosorbent assay method was used to evaluate blood levels of interleukins -1 and 22 in both infected and healthy control groups. The highest frequency of bacterial isolates was obtained from 15-30 age group with 32.9%, followed by 31-50 age group with 26.3%, 51-70 age group with 19.7% and >70 age group with 14.5%. The lowest bacterial frequency was obtained from the <15 age group with 6.6%, and when analyzed by gender, a higher frequency was observed in females (60.5%) compared to males (39.5%). Bacterial isolates collected from burn samples (51.3%) were higher than bacterial isolates collected from wounds (48.7%). Of the 76 bacterial isolates, 46.1% had strong biofilm forming capacity, 27.6% had moderate biofilm forming capacity and 18.4% had weak biofilm forming capacity. On the other hand, 7.9% were not capable of biofilm formation. The highest resistance rate among bacterial isolates was observed against Cefotaxime (78.95%), followed by Norfloxacin (69.74%). The medium resistance rate was observed against Cefepime (51.32%), followed by Ceftazidime (50%) and Piprasilin-Tazobactam (48.68%). On the other hand, the lowest resistance rates were to Ciprofloxacin (39.47%), Gentamicin (36.84%), Imipenem and Meropenem (35.53%), respectively. In addition, the lowest resistance rate was observed against Amikacin (34.21%). The prevalence of virulence genes among the bacterial isolates was high and ranked as algD (90.79%), plcH (59%), plcN (76.32%), LasB (77.63%) and exoS (73.68%). In immunological terms, the mean IL-1 and IL-22 serum levels of the patients infected with P. aeruginosa (5.235±1.160 and 30.93±4.289 pg/mL, respectively) were higher than the control group (3.838±1.050 and 23.39±4.243 pg/mL, respectively). In addition, there was a statistically significant difference between both study groups in terms of IL-1 and IL-22 serum levels (p value<0.0001). In conclusion, the bacterium Pseudomonas aeruginosa plays a unique role in nosocomial infections, especially in burn and wound cases. This is because they show a wide spectrum of resistance to antibiotics, as well as their capacity to form biofilms and possess many virulence genes that allow them to exacerbate infection and make it difficult to treat. Research has also shown that the immune response plays a notable role in reducing the pathogenicity of bacterial infections. This is because the immune response can be used as a technique to help overcome isolates that show high levels of virulence and resistance to drugs.