Multidrug-resistant Klebsiella pneumoniae: genetic diversity, mechanisms of resistance to polymyxins and clinical outcomes in a tertiary teaching hospital in Brazil

• Published in: Revista do Instituto de Medicina Tropical de São Paulo
• Main Authors: Icaro Boszczowski, Matias Chiarastelli Salomão, Maria Luísa Moura, Maristela Pinheiro Freire, Thais Guimarães, Ana Paula Cury, Flávia Rossi, Camila Fonseca Rizek, Roberta Cristina Ruedas Martins, Silvia Figueiredo Costa
• Format: Article in Journal/Newspaper
• Language: English
• Published: Universidade de São Paulo (USP)
• Subjects: Colistin resistance; Hospital epidemiology; Antibiotic therapy; Genome sequencing; Polymyxins; Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Arctic
• Online Access: https://doi.org/10.1590/s1678-9946201961029; https://doaj.org/article/9e0242546dc746a6854392e46f20116f

ABSTRACT Increased resistance to polymyxin in Klebsiella pneumoniae (ColRKP) has been observed. Molecular epidemiology, as well as the clinical impact of these difficult to treat pathogens need to be better characterized. We present the clinical outcomes of 28 patients infected by ColRKP in a tertiary hospital. Isolates with MIC >2 by Vitek 2 were confirmed by the microdilution broth test. Polymerase chain reaction (PCR) was performed for blaKPC, blaNDM, blaOXA-48 and blamcr-1 genes in the isolates, and Whole Genome Sequencing (WGS) was performed in six isolates. Seventeen (61%) patients were female and the mean age was 50 years old. In-hospital and 30-day mortality were 64% (18/28) and 53% (15/28), respectively. Central line-associated bloodstream infection in addition to bacteremia episodes due to other sources were the most frequent (61%). Mean APACHE and Charlson comorbidity index were 16 and 5, respectively. Twenty patients (71%) received at least one active drug and ten (35%) received two drugs: tigecycline 46% (13/28); amikacin 21% (6/28) and fosfomycin 3% (1 case). Twenty-six out of 28 tested cases were positive for blaKPC. Eight different clusters were identified. Four STs were detected (ST11, ST23, ST340, and ST437). Mutations on pmrA, arnB, udg, and yciM genes were present in all six isolates submitted to WGS; lpxMand mgrB mutations were also detected in all but one isolate. In conclusion, we observed resistance to polymyxin in severely ill patients mostly from intensive care units and/or immunosuppressed patients with high mortality rates in whom a diversity of ColRKP clusters was identified and might indicate selective pressure.