Genotyping of paired KPC-producing Klebsiella pneumoniae isolates with and without divergent polymyxin B susceptibility profiles

Author(s)

Ferreira Sampaio, Suely Carlos ^{[1, 2]} ; Bigelli Carvalho, Rozane de Lima ^[1] ; Mimica, Marcelo Jenne ^[1] ; da Silva, Cely Barreto ^[3] ; Jenne Mimica, Lycia Mara ^[1] ; de Lima, Aline Valerio ^[2] ; Lima, Keila de Oliveira ^[2] ; da Costa Rocha, Darlan Augusto ^[2] ; Mello Sampaio, Jorge Luiz ^{[2, 4]}

Affiliation

^[1] Med Sci Sch, Dept Pathol, Div Microbiol, Sao Paulo, SP - Brazil

^[2] Univ Sao Paulo, Antimicrobial Resistance & Clin Microbiol Lab RAM, Sch Pharmaceut Sci, Sao Paulo, SP - Brazil

^[3] Infect Control & Prevent Serv, Sao Paulo, SP - Brazil

^[4] Fleury Med & Hlth, Microbiol Sect, Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: Brazilian Journal of Microbiology; v. 52, n. 4 AUG 2021.
• Web of Science Citations: 0

Abstract

Polymyxins are still used mainly in treating infections caused by carbapenem-resistant Klebsiella pneumoniae worldwide. The most frequent mechanism of acquired resistance to polymyxins in Gram-negative bacilli is the occurrence of mutations in chromosomal genes regulating operons responsible for lipopolysaccharide modification. As we observed at Santa Casa de Sao Paulo hospital the occurrence of infections caused by isolates resistant to polymyxins in patients previously treated with this antimicrobial, and new infections caused by the same polymyxin-susceptible species, in this study, we aimed to determine the clonality of consecutive K. pneumoniae isolates from the same patients and characterize the molecular determinants of polymyxin resistance in paired or clonal isolates. A total of 24 pairs and one trio of K. pneumoniae isolates were included in this study. Species identification was achieved by mass spectrometry and multiplex PCR. Polymyxin B minimal inhibitory concentrations were determined by broth microdilution. Clonality was evaluated using pulsed-field gel electrophoresis. The presence of insertions in mgrB gene was tested by PCR, and mutations on pmrA, pmrB, phoP, and phoQ were evaluated by PCR and complete nucleotide sequencing. A fraction of 23.8% of strains resistant to polymyxin B had an insertion in mgrB. Amino acid substitution F204L in PmrB may be implicated in polymyxin resistance. Substitutions T246A and R256G in PmrB were not implicated in polymyxin resistance. In this study, polymyxin resistance after a first susceptible isolate was detected was most frequently due to an infection caused by a distinct clone. (AU)

• FAPESP's process: 16/07995-6 - New or emerging carbapenemases and their genetic background in Acinetobacter spp. and Pseudomonas aeruginosa
• Grantee: Jorge Luiz Mello Sampaio
• Support Opportunities: Regular Research Grants