Investigating the Frequency of AlgD Gene in Clinical Isolates of Pseudomonas Aeruginosa Collected from Teaching-Therapeutic Hospitals of Mazandaran-2022

Pseudomonas aeruginosa is an opportunistic nosocomial pathogen, which is resistant to different groups of antibiotics. Infections caused by this organism due to antibiotic resistance may ultimately cause high mortality. The ability of this microorganism to produce pathogenic factors such as alginate, proteases, pyocyanin, rhamnolipid, phospholipase C, the presence of pili, and the ability to form biofilm and colonization have made this bacterium one of the most important pathogens. Considering that alginate is one of the important pathogenic factors of this microorganism which mainly algA, algC, and algD genes encode enzymes necessary for the leading biosynthesis pathway of alginate-GDP-mannuronic acid. Therefore, in the current study, we investigated the frequency of the algD gene in P. aeruginosa isolated from patients hospitalized in Mazandaran hospitals using specific primers by PCR method.

According to the results of past studies and using the sample size formula to calculate the prevalence and considering the maximum error of 0.05, the confidence level of 0.95, the ratio of 0.97, and the sample size of the unlimited population was estimated to be 100 isolates. Clinical isolates of P. aeruginosa were collected from different laboratories of Mazandaran educational hospitals. After collecting the clinical isolates of P. aeruginosa and definitively identifying the bacteria by performing routine biochemical tests, the antibiotic resistance pattern of the isolates was checked with Agar Diffusion Disk. In the next step, we extracted the DNA of P aeruginosa strains by alkaline lysis method by adding sodium dodecyl sulfate and NaOH. Finally, a PCR test was performed using the specific primer of the algD gene. Then, the PCR product was evaluated using a UV Transilluminator device. Data were analyzed using SPSS software.

100 isolates of P. aeruginosa were isolated from 100 hospitalized patients. These isolates were collected from five medical educational hospitals of Mazandaran province, which were as follows: Imam Khomeini Hospital in Sari (40 isolates), Razi Hospital in Qaemshahr (22 isolates), Bo Ali Sina Hospital in Sari (17 isolates), Zare Psychiatric and Burn hospital in Sari (11 isolates), and Fatemeh Zahra heart hospital in Sari (10 isolates). Most of the clinical isolates of P. aeruginosa in the present study were obtained from sputum samples (37/100) and in second place from urine samples (26/100) of patients. 98 isolates had the algD gene. 26% of isolates were resistant to Piperacillin, 39% of isolates to Aztreonam, 27% of isolates to Ceftazidime, 31% of isolates to Imipenem, 39% to Tobramycin and 41% to Ciprofloxacin. All clinical isolates resistant to studied antibiotics carried the algD gene. Only two isolates of the sensitive strains of this organism in each group of antibiotics lacked the desired gene.

The results of the present study show that the algD gene is present in most of the clinical isolates of the P. aeruginosa strain obtained from medical education centers in Mazandaran. On the other hand, the high prevalence of this organism and the high resistance to antibiotics and multiple drugs observed in the current study and previous studies have turned the treatment of infections caused by P. aeruginosa into a serious and complex problem. Finally, considering that the algD gene plays a significant role in the formation of biofilm and antibiotic resistance, the results of the current study also confirm this finding.