Screening of Antimicrobial Resistance Genes and Epidemiological Features in Hospital and Community-Associated Carbapenem-Resistant Pseudomonas aeruginosa Infections

Introduction: Researching carbapenem-resistant isolates enables the identification of carbapenemase-producing bacteria and prevents their spread. Methods: P. aeruginosa isolates were recovered from Medicine Faculty of Recep Tayyip Erdogan University and identified by conventional methods and the automated Vitek 2 Compact system. Antimicrobial susceptibility experiments were performed in accordance with CLSI criteria and the automated Vitek 2 Compact system. The PCR method was investigated for the presence of beta-lactamase resistance genes. PFGE typing was performed to show clonal relation among samples. Results: Seventy P. aeruginosa isolates were isolated from seventy patients. Of the patients, 67.1% had contact with the health service in the last 90 days and 75.7% of the patients had received antimicrobial therapy in the previous 90 days. Twenty-four isolates were carbapenem resistant, 2 isolates were multidrug-resistant except colistin, and none of the samples had colistin resistance. The gene encoding beta-lactamase or metallo-beta-lactamase was found in a total of 36 isolates. The bla(VEB) and bla(PER) genes were identified in 1 and 5 isolates alone or 17 and 13 isolates in combination with other resistance genes, respectively. The bla(NDM) was the most detected metallo-ss-lactamase encoding gene (n=18), followed by bla(KPC) (n=12). bla(IMP) and bla(VIM) were detected in 5 and 1 isolates, respectively. Also, the association of bla(VEB)-bla(PER) and bla(VEB)-bla(KPC)-bla(NDM) was found to be very high. Much more resistance genes and co-occurrence were detected in hospital-acquired samples than community-acquired samples. No difference was found between the community and hospital-associated isolates according to PFGE results. Simultaneously from 6 patients, other microorganisms were also isolated and 5 of them died. Conclusion: The average length of stay (days) was found to be significantly higher in HAI group than CAI group. The death of 5 patients with fewer or no resistance genes showed that the co-existence of other microorganisms in addition to resistance genes was important on death.

Automated summary

Researching carbapenem-resistant isolates revealed a high prevalence of bacteria carrying beta-lactamase and metallo-beta-lactamase genes, with more resistance genes and coexistence found in hospital-acquired samples. There was no difference between community and hospital-associated isolates in PFGE results, but a significant difference was observed in terms of fatality rates, indicating the importance of other microorganisms coexisting with resistance genes in patient outcomes.