Detection of bla OXA-145, bla OXA-224, bla OXA-539, and bla OXA-675 Genes and Carbapenem-Hydrolyzing Class D β -Lactamases (CHDLs) in Clinical Isolates of Pseudomonas aeruginosa Collected from West of Iran, Hamadan.

Carbapenem-hydrolyzing class D β -lactamases (CHDLs) are on the rise and are a major public health problem worldwide. Pseudomonas aeruginosa is resistant to carbapenem; currently, the most effective treatment option is being increasingly reported. This study aimed to identify bla OXA-145, bla OXA-224, bla OXA-539, and bla OXA-675 genes in CHDL strains. Samples were collected from clinical specimens admitted to the hospital. Antibiotic susceptibility was determined using the disk diffusion methods. CHDL strains were detected using a phenotypic method (disk diffusion). The PCR method was used to identify bla OXA-145, bla OXA-224, bla OXA-539, and bla OXA-675 genes. Piperacillin-resistant strains ( n  = 9, 17.4%) had the lowest frequency, and cefoxitin-resistant strains ( n  = 100, 91.7%) had the highest distribution in P. aeruginosa isolates. Also, 29.35%, 12.8%, and 8.2% were multidrug-resistant, extensively drug-resistant, and pan drug-resistant, respectively. MBL-producing P. aeruginosa and KPC-producing P. aeruginosa were detected, respectively, in 47.7% and 37.6% of isolates. Biofilm formation was observed in 63.3% of P. aeruginosa isolates. The frequency of OXA genes was as follows: bla OXA-145 gene in 30 isolates (27.5%), bla OXA-224 in 24 isolates (22.0%), bla OXA-539 in 22 isolates (20.1%), and bla OXA-675 in 13 isolates (11.9%). However, 19 (17.4%) isolates carry all bla OXA-145, bla OXA-224, bla OXA-539, and bla OXA-675 genes. The antimicrobial resistance and OXA genes among biofilm former strains were significantly higher than those of nonbiofilm former strains ( p < 0.05). The emergence of carbapenem-resistant isolates of P. aeruginosa has posed serious threats to the community because they exhibit multiple drug resistance, thus limiting the therapeutic options for clinicians.