Akademik Veri Yönetim Sistemi
BIO Türkiye-Uluslararası Biyoteknoloji Kongresi, İstanbul, Türkiye, 28 - 30 Eylül 2023, ss.25, (Özet Bildiri)
Introduction: Pseudomonas aeruginosa is a multidrug resistant opportunistic pathogen that causes infections especially in hospitalized patients and immunocompromised individuals. It is on the list of "Bacteria that pose a serious threat to human health" by the American Center for Disease Prevention and Control [1]. Carbapenems are the main antibiotics used to treat infections caused by P. aeruginosa; however, carbapenem resistance in P. aeruginosa strains is increasing worldwide [2]. The development of resistance to carbapenems is mostly due to loss of OprD porin protein and increased activation of efflux pump proteins. In P. aeruginosa, resistance due to A, D class serine carbapenemases and molecular B class metallo-beta lactamases (MBL) has also been reported frequently in recent years. [3,4]. The time required to detect carbapenem resistance in the routine laboratory is about 48 hours. This delays the initiation of effective treatment, especially in critically ill patients. For this reason, researches focus on new methods to detect bacterial resistance earlier. In this study, it was aimed to investigate carbapenemase production by phenotypic and genotypic methods in clinical P.aeruginosa isolates resistant to carbapenems.
Materials and Methods: 100 carbapenem-resistant and 15 carbapenem-susceptible P. aeruginosa isolates obtained from patients and routinely tested for antibiotic susceptibility between January 2018 and February 2023 at the Microbiology Laboratory in M.U. Pendik Training and Research Hospital were included. In the investigation of carbapenemase production, a colorimetric method based on enzyme-substrate reaction was used as a phenotypic test. P. aeruginosa isolates were grown by overnight cultivation then suspended in Tris HCl for lysis of bacteria. Bacterial lysate was added to the solution containing imipenem and phenol red, then incubated for 1 hour at room temperature. Samples with color change from red to orange/yellow were recorded as carbapenemase positive. Carbapenem resistance was genotypically investigated by real-time PCR (RT-PCR).
Results: In this study, carbapenemase production was detected in 35 (35%) of 100 carbapenem resistant isolates by phenotypic and genotypic methods. Positive results were recorded within 1 hour using the phenotypic method. P. aeruginosa isolates found to produce carbapenemase enzyme were most commonly isolated from urine and catheter tip samples. The investigated genes were not detected in the isolates (N=65) that were found to be carbapenemase negative by phenotypic testing. In these isolates, carbapenem resistance can be attributed to other resistance mechanisms such as porin loss (OprD etc.), efflux pump activation and AmpC overexpression.
Conclusions: Starting an effective antibiotic treatment in the earlier phase is life-saving in antibiotic-resistant bacterial infections. Today, various rapid but costly commercial diagnostic methods such as PCR tests are used for the detection of antibiotic resistance. Reliable, rapid, and cost-effective tests to detect resistant bacteria or infections in the routine laboratory are needed for appropriate treatment and effective infection control measures. The phenotypic method based on the colorimetric detection of enzyme-substrate reaction used in our study can detect carbapenemase-producing isolates in a short time with low-cost.