Identification of Extended Spectrum Beta Lactamases (ESBLS) in Clinical Isolates of Pseudomonas Aeruginosa through both Phenotypic and Genotypic Methods in Kerbala Hospitals

Abstract

Background:  Pseudomonas aeruginosa is known as a notable opportunistic bacterium associated with Hospital-acquired infections in immunodeficient and seriously ill individuals. It's also a significant pathogen among the ESKAPE bacteria and tops the WHO priority list which requires monitoring of the epidemiological status and the evolution of antibiotic resistant. Among different resistance mechanisms, ß-lactamases production are the most critical resistance mechanism in P. aeruginosa. Within these ß-lactamases, ESBL-producing P. aeruginosa is a challenge to infection control worldwide. The research aim: The present research aimed to define the phenotypic and genotypic ESBL production in various clinical isolates of P. aeruginosa strains including bla_CTX-M-1 gene, bla_CTX-M-9 gene, bla_TEM gene, bla_SHV gene, and bla_OXA gene in Karbala hospitals. Methods: From three major hospitals in Karbala, 2409 samples were gathered from July 2024 to November 2024. These samples were collected from various clinical infection including urine, sputum, swabs (burn and wound), and fluids (blood and CSF). The isolates were tested for the presence of P. aeruginosa by conventional culture methods and confirmed by the VITEK-2 system. The double-disk synergy test (DDST) by using a third-generation cephalosporin and clavulanate and antibiotic susceptibility test by using Kirby Bauer discs diffusion with 25 antimicrobial agents were done regarding to CLSI instructions. Finally, the genotypic detection of five targeted ESBL genes was done using the PCR technique. Results: In the current research, a total of 104 (4.3%) strains of P. aeruginosa were gathered from various clinical samples. According to the antibiotic sensitivity profile of P. aeruginosa isolates in the current research, the highest resistance rate (100%) was observed against carbenicillin, augmentin, and cefotaxime. In contrast, colistin and polymyxin demonstrated complete effectiveness against all isolates. Among the quinolone agents, ciprofloxacin, norfloxacin, and levofloxacin exhibited the lowest sensitivity rates, reported at 41.3%, 44.2%, and 48.8%, respectively. The current study exhibited that 59 (56.73%) of the isolates were considered multi-drug resistant (MDR), while the XDR isolates comprised 45 (43.27%) of the isolates. Regarding to the double-disk synergy test (DDST) results, 19.2% (20 out of 104) of P. aeruginosa isolates were selected as ESBL-producing strains. Additionally, of the 20 phenotypically-identified ESBL producers, nine of them (45%) were identified carrying at least one of the tested ESBL genes. Notably, the most frequent gene was bla_OXA with a rate of 35%. Followed by bla_TEM in rate 20%. Whereas bla_CTX-M-1 was identified in 15%. However, the less predominant genes among these ESBLs were bla_CTX-M-9 and bla_SHV at rates of 5% per each one. Conclusion: This research demonstrates that the emergence of ESBL in P. aeruginosa is escalating in Karbala hospitals, complicating effective treatment. Early identification of these enzymes plays a key role in preventing deaths and halting the gene-driven spread of resistant pathogens. It is therefore necessary to adopt comprehensive strategies to combat these threats.