Investigation of virulence factors in Pseudomonas aeruginosa isolates by phenotypic and genotypic methods.

INTRODUCTION: Pseudomonas aeruginosa possesses a variety of virulence factors that may contribute to its pathogenicity, and relationship has been determined between antibiotic resistance and biofilm. The aim of this study was to investigate the virulence factors of Pseudomonas aeruginosa isolates by genotypic and phenotypic methods, as well as whether there is a relationship between other virulence factors and antibiotic resistance. METHODS: A total of 80 Pseudomonas aeruginosa strains were sent from various clinics included in the study. Identification and antibiotic resistance profile of isolates were determined by Vitek 2 (Biomerioux, France) automated system. Pseudomonas P agar, Pseudomonas F agar, and motility test medium were used for phenotyping tests. Tox A, Exo S, Plc N, and Las B were evaluated with Real-time PCR (Anatolia, Geneworks, Turkey). RESULTS: The highest rates of antibiotic resistance were observed against imipenem (42.5%) and meropenem (40%). Among the isolates, 81.3% tested positive for Tox A, 30% for Exo S, 32.5% for Plc N, and 42.5% for Las B. Additionally, 70.4% of the isolates tested positive for pyocyanin, 41.3% for pyoverdine, 1.8% for pyorubin, and 8.9% tested negative for pyorubin. No statistically significant difference was found between antibiotic resistance and the presence of virulence factors (p > 0.005). CONCLUSIONS: The relationship between antibiotic resistance and virulence factors is controversial. There are studies demonstrating the relationship between virulence factors and antibiotic resistance, as well as studies that indicate the absence of such a relationship. Investigating virulence and antibiotic resistance rates may be important for identifying potential drug targets for subsequent research.

Evaluation of toxin-antitoxin genes, antibiotic resistance, and virulence genes in Pseudomonas aeruginosa isolates.

OBJECTIVE: Toxin-antitoxin genes RelBE and HigBA are known to be involved in the formation of biofilm, which is an important virulence factor for Pseudomonas aeruginosa. The purpose of this study was to determine the presence of toxin-antitoxin genes and exoenzyme S and exotoxin A virulence genes in P. aeruginosa isolates and whether there is a relationship between toxin-antitoxin genes and virulence genes as well as antibiotic resistance. METHODS: Identification of the isolates and antibiotic susceptibilities was determined by a VITEK 2 (bioMérieux, France) automated system. The presence of toxin-antitoxin genes, virulence genes, and transcription levels were detected by real-time polymerase chain reaction. RESULTS: RelBE and HigBA genes were detected in 94.3% (82/87) of P. aeruginosa isolates, and exoenzyme S and exotoxin A genes were detected in all of the isolates (n=87). All of the isolates that harbor the toxin-antitoxin and virulence genes were transcribed. There was a significant increase in the RelBE gene transcription level in imipenem- and meropenem-sensitive isolates and in the HigBA gene transcription level in amikacin-sensitive isolates (p<0.05). There was a significant correlation between RelBE and exoenzyme S (p=0.001). CONCLUSION: The findings suggest that antibiotic resistance may be linked to toxin-antitoxin genes. Furthermore, the relationship between RelBE and exoenzyme S indicates that toxin-antitoxin genes in P. aeruginosa isolates are not only related to antibiotic resistance but also play an influential role in bacterial virulence. Larger collections of comprehensive studies on this subject are required. These studies should contribute significantly to the solution of the antibiotic resistance problem.

Effect of mazEF, higBA and relBE toxin-antitoxin systems on antibiotic resistance in Pseudomonas aeruginosa and Staphylococcus isolates.

Background: A toxin-antitoxin (TA) system is a set of two or more closely linked genes that are encoded as a poison and a corresponding antidote on a protein. In typical bacterial physiology, an antitoxin binds to a toxin and neutralizes it, which prevents the bacterium from killing itself. We aimed to determine whether P.aeruginosa and Staphylococcus isolates have TA genes and to investigate whether there is a relationship between the expression levels of TA genes and resistance to antibiotics. Methods: This study included 92 P. aeruginosa and 148 Staphylococcus isolates. RelBE, higBA genes were investigated in P.aeruginosa by multiplex polymerase chain reaction (PCR). The mazEF gene and the all TA genes expression were detected by real time PCR. Results: RelBE and higBA genes were detected in 100% of P. aeruginosa. It was found that the level of relBE TA gene expression is increased in isolates sensitive to aztreonam compared to resistant isolates (p<0.05). The mazEF gene was detected in 89.1% of Staphylococcus isolates. In terms of MazEF gene expression level there was no significant difference between methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) isolates (p>0.05) whereas there was a significant difference between MSSA and coagulase-negative Staphylococcus (CNS) isolates, MRSA and CNS isolates (p<0.05). The levels of mazEF gene expression were found to be higher in isolates sensitive to gentamicin, ciprofloxacin, levofloxacin, clindamycin, phosphomycine, nitrofurantoin, fusidic acid, cefoxitin compared to resistant isolates (p<0.05). Conclusion: Studies on the prevalence and functionality of TA systems emphasize that it may be possible to have new sensitive regions in bacteria by activating TA systems. The results of this study lead to the idea that resistance to antibiotics can be reduced by increasing TA gene expression levels. But there is need for further studies to support and develop this issue.