Clinical Significance of Carbapenem-Tolerant <i>Pseudomonas aeruginosa</i> Isolated in the Respiratory Tract

• Main Authors: Momoyo Azuma (Author), Keiji Murakami (Author), Rina Murata (Author), Keiko Kataoka (Author), Hideki Fujii (Author), Yoichiro Miyake (Author), Yasuhiko Nishioka (Author)
• Format: Book
• Published: MDPI AG, 2020-09-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 10.3390/antibiotics9090626; 2079-6382
• Keywords: carbapenem tolerance; antibiotic tolerance; <i>Pseudomonas aeruginosa</i>; respiratory tract infection; persistent infections; Therapeutics. Pharmacology; RM1-950
• Source: Antibiotics, Vol 9, Iss 9, p 626 (2020)

We often come across difficult to treat infections-even after administering appropriate antibiotics according to the minimal inhibitory concentration of the causative bacteria. Antibiotic tolerance has recently started to garner attention as a crucial mechanism of refractory infections. However, few studies have reported the correlation between clinical outcomes and antibiotic tolerance. This study aims to clarify the effect of antibiotic tolerance on clinical outcomes of respiratory tract infection caused by <i>Pseudomonas aeuginosa</i> (<i>P. aeruginosa</i>). We examined a total of 63 strains isolated from sputum samples of different patients and conducted a retrospective survey with the medical records of 37 patients with imipenem-sensitive <i>P. aeruginosa</i> infections. Among them, we selected 15 patients with respiratory infections, and they were divided into high-tolerance minimal bactericidal concentration for adherent bacteria (MBC^AD)/minimal inhibitory concentration for adherent bacteria (MIC^AD) ≥ 32 (<i>n</i> = 9) group and low-tolerance MBC^AD/MIC^AD ≤ 16 (<i>n</i> = 6) group for further investigations. The findings indicated that the high-tolerance group consisted of many cases requiring hospitalization. Chest computed tomography findings showed that the disease was more extensive in the high-tolerance group compared to the low-tolerance group. Regarding the bacterial phenotypic characterization, the high-tolerance group significantly upregulated the production of the virulence factors compared to the low-tolerance group. Our study provided evidence that carbapenem tolerance level is a potent prognostic marker of <i>P. aeruginosa</i> infections, and carbapenem tolerance could be a potential target for new antimicrobial agents to inhibit the progression of persistent <i>P. aeruginosa</i> infections.