Plasmid-related β-lactamase genes in Pseudomonas aeruginosa isolates: a molecular study in burn patients
Mahrokh Rajaee Behbahani1, Abdolkhalegh Keshavarzi2, Neda Pirbonyeh1
1Burn & Wound Healing Research Center, Microbiology Department, Shiraz University of Medical Sciences, Shiraz, Iran.
Abstract:
Introduction. One of the most important resistant mechanisms in Gram-negative bacteria is extended spectrum β-lactamases (ESBLs). Harbour-related genes on plasmids, increase the risk of resistance transmission among commonly reported hospital infections.Aim. This study was designed to explore the dissemination of Pseudomonas aeruginosa producing ESBLs on their plasmids recovered from the different wards of Amir-Al-Momenin burn center, Affiliated with Shiraz University of Medical Sciences.Methodology. Among 256 isolates, 88 (34.38 %) P. aeruginosa strains were isolated from burn hospitalized patients. Samples were processed for antibiotic resistance using the Kirby-Bauer method while MIC was performed for colistin. MIC was used by the microdilution broth method as recommended by Clinical and Laboratory Standards Institute guidelines. Related studied genes were evaluated on extracted plasmids by the PCR method.Results. According to the phenotypic and molecular steps, a total of 58 (65.91 %) and 74 (84.10 %) strains detected positive ESBLs, respectively. Based on antibiogram tests, a total of 63 (71.59 %) isolates were detected as multidrug resistant. All ESBL P. aeruginosa isolates showed identical antimicrobial susceptibility profiles. The genotypic prevalence of ESBLs for bla SHV, bla TEM, bla GES, bla OXA-10 and bla PSE genes was 47.73, 78.41, 5.58, 3.41, 4.55 %, respectively.Conclusion. All P. aeruginosa strains producing ESBLs had plasmids containing related genes. The data indicated a high prevalence of ESBL among P. aeruginosa isolates in the southwest of the Iran burn center and their enzyme types were diverse.
Insights
Extended spectrum β-lactamases (ESBLs) are a major resistance mechanism in Gram-negative bacteria. This study found a high prevalence of ESBL-producing Pseudomonas aeruginosa on plasmids in an Iranian burn center.
Area of Science:
- Microbiology
- Infectious Diseases
- Genetics
Background:
- Extended spectrum β-lactamases (ESBLs) represent a critical resistance mechanism in Gram-negative bacteria.
- Plasmid-mediated ESBL genes facilitate rapid transmission of antibiotic resistance, particularly in hospital settings.
Purpose of the Study:
- To investigate the prevalence and genetic characteristics of ESBL-producing *Pseudomonas aeruginosa* isolates from a burn center in Shiraz, Iran.
- To identify the specific ESBL genes harbored on plasmids within these resistant strains.
Main Methods:
- Antibiotic susceptibility testing (Kirby-Bauer, MIC) and molecular methods (PCR) were employed.
- Isolates were obtained from burn patients at Amir-Al-Momenin burn center.
- Plasmid DNA was extracted and analyzed for the presence of ESBL genes.
Main Results:
- Out of 88 *P. aeruginosa* isolates, 65.91% (phenotypic) and 84.10% (molecular) were ESBL-positive.
- Multidrug resistance was observed in 71.59% of isolates.
- Prevalent ESBL genes included *bla*TEM (78.41%) and *bla*SHV (47.73%).
Conclusions:
- A high prevalence of ESBL-producing *P. aeruginosa* strains carrying resistance genes on plasmids was identified.
- The findings highlight the significant burden of antibiotic resistance in this burn center.
- Diverse ESBL enzyme types were detected, underscoring the need for effective infection control strategies.
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