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. 2024 Sep 24;7(9):e70095.
doi: 10.1002/hsr2.70095. eCollection 2024 Sep.

Phenotypic and genotypic identification of class C and D β-lactamases in clinical isolates of Pseudomonas aeruginosa: a cross-sectional study

Nahid Mohammadnezhad  1 , Maryam Nazari  2 , Seyyed Khalil Shokouhi Mostafavi  1 , Amirhossein Sahebkar  3   4   5 , Farzad Khademi  2   6
Affiliations

Phenotypic and genotypic identification of class C and D β-lactamases in clinical isolates of Pseudomonas aeruginosa: a cross-sectional study

Nahid Mohammadnezhad et al. Health Sci Rep. .

Abstract

Background and aims: The emergence of Pseudomonas aeruginosa (P. aeruginosa) antibiotic resistance is an important public health problem worldwide that can negatively affect infection control. Therefore, obtaining knowledge about antibiotic resistance mechanisms is necessary for infection control policies. This study aimed to determine the frequency of class C and D β-lactamases in P. aeruginosa strains isolated from patients referred to Ardabil hospitals using phenotypic and genotypic tests.

Methods: Phenotypic detection of β-lactamases including AmpC cephalosporinase, oxacillinase (OXA)-type extended-spectrum β-lactamases (ESBLs), and OXA-type carbapenemases were performed using the disk diffusion-based methods. Amplification of genes encoding classes C (ampC and FOX genes) and D (OXA-1, OXA-2, OXA-10, OXA-23, and OXA-48 genes) β-lactamases was performed using the polymerase chain reaction (PCR) method. A quantitative reverse transcription PCR (qRT-PCR) method was used to determine the expression level of the ampC gene among multiple drug-resistant and imipenem-resistant P. aeruginosa strains.

Results: In phenotypic tests, the prevalence of AmpC cephalosporinase, OXA-type ESBLs, and OXA-type carbapenemases were 52.5%, 7.2%, and 95.8%, respectively. In genotypic tests, the prevalence of ampC, FOX, OXA-1, OXA-2, OXA-10, OXA-23, and OXA-48 genes were 100%, 0%, 4.3%, 60.8%, 42%, 29.7%, and 2.9%, respectively. In addition, the ampC gene overexpression was seen in 16 (33.3%) drug-resistant P. aeruginosa clinical isolates.

Conclusion: Given the presence of class C and D β-lactamases in clinical isolates of P. aeruginosa in Ardabil hospitals, early detection of these strains can help prevent the spread of resistant strains in hospital environments and subsequent treatment failure.

Keywords: AmpC beta‐lactamase; OXA‐type β‐lactamase; Pseudomonas aeruginosa; extended‐spectrum β‐lactamase.

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Conflict of interest statement

The authors declare that there is no conflict of interest.

Figures

Figure 1
Figure 1
Phenotypic detection of AmpC β‐lactamase (A), OXA‐type ESBLs (B), and OXA‐type carbapenemases (C) in clinical isolates of P. aeruginosa. FOX: cefoxitin, FOX‐BRO: cefoxitin plus phenylboronic acid, CTX: cefotaxime, CTC: cefotaxime‐clavulanate, CAZ: ceftazidime, CAZ‐BRO: ceftazidime plus phenylboronic acid, CZA: ceftazidime‐clavulanate, CZA‐BRO: ceftazidime‐clavulanate plus phenylboronic acid.
Figure 2
Figure 2
Results of gene amplification in the PCR method. Lane 1: ampC (279 bp), Lane 2: OXA‐1 (909 bp), Lane 3: OXA‐2 (701 bp), Lane 4: OXA‐10 (775 bp), Lane 5: OXA‐23 (513 bp), Lane 6: OXA‐48 (438 bp), and Lane M: ladder (100 bp).
Figure 3
Figure 3
The overproduction of chromosomal AmpC cephalosporinase among drug‐resistant P. aeruginosa clinical isolates. An increased level of the ampC gene transcription was observable among P. aeruginosa isolates. Each red circle represents a clinical strain.
See this image and copyright information in PMC

References

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