Acinetobacter baumannii is involved in life-threatening nosocomial infections, mainly in the intensive care units (ICUs), and often colistin may represent the last therapeutic opportunity. The susceptibility to colistin of 51 epidemiologically typed A. baumannii strains isolated in 2017 from clinical samples of patients hospitalized in the ICU of a tertiary care academic hospital was investigated. All isolates were carbapenem-resistant due to the presence of the blaOXA-23 gene in sequence group 1 (international clonal lineage II) and sequence group 4 (related to international clonal lineage II) isolates, and to the blaOXA-24/40 gene in sequence group 2 (international clonal lineage I) isolates. Vitek®2, agar diffusion, and broth microdilution tests showed major discordancy (≥2 dilution factors) in the minimum inhibitory concentration (MIC) values for colistin in 24 out of 51 isolates, resulting in erroneous reporting of qualitative susceptibility data for eight isolates. In growth kinetics experiments in the presence of colistin, five isolates grew with drug concentrations above the susceptibility breakpoint when incubated for >12 h, and three isolates showed the presence of heteroresistant subpopulations. This study highlights that the high frequency of isolation of carbapenem-resistant A. baumannii strains in high-risk infectious wards requires an accurate application of methods for detecting susceptibility to antibiotics, in particular to colistin, so as to ensure a correct therapeutic approach.

Susceptibility testing of colistin for acinetobacter baumannii: How far are we from the truth? / Sacco, F.; Visca, P.; Runci, F.; Antonelli, G.; Raponi, G.. - In: ANTIBIOTICS. - ISSN 2079-6382. - 10:1(2021), pp. 1-12. [10.3390/antibiotics10010048]

Susceptibility testing of colistin for acinetobacter baumannii: How far are we from the truth?

Sacco F.
Writing – Original Draft Preparation
;
Antonelli G.
Validation
;
Raponi G.
Conceptualization
2021

Abstract

Acinetobacter baumannii is involved in life-threatening nosocomial infections, mainly in the intensive care units (ICUs), and often colistin may represent the last therapeutic opportunity. The susceptibility to colistin of 51 epidemiologically typed A. baumannii strains isolated in 2017 from clinical samples of patients hospitalized in the ICU of a tertiary care academic hospital was investigated. All isolates were carbapenem-resistant due to the presence of the blaOXA-23 gene in sequence group 1 (international clonal lineage II) and sequence group 4 (related to international clonal lineage II) isolates, and to the blaOXA-24/40 gene in sequence group 2 (international clonal lineage I) isolates. Vitek®2, agar diffusion, and broth microdilution tests showed major discordancy (≥2 dilution factors) in the minimum inhibitory concentration (MIC) values for colistin in 24 out of 51 isolates, resulting in erroneous reporting of qualitative susceptibility data for eight isolates. In growth kinetics experiments in the presence of colistin, five isolates grew with drug concentrations above the susceptibility breakpoint when incubated for >12 h, and three isolates showed the presence of heteroresistant subpopulations. This study highlights that the high frequency of isolation of carbapenem-resistant A. baumannii strains in high-risk infectious wards requires an accurate application of methods for detecting susceptibility to antibiotics, in particular to colistin, so as to ensure a correct therapeutic approach.
2021
Acinetobacter baumannii; Broth microdilution; Colistin; Intensive care unit; International clone lineages; Multidrug-resistant; OXA enzymes; Sequence group; Susceptibility testing
01 Pubblicazione su rivista::01a Articolo in rivista
Susceptibility testing of colistin for acinetobacter baumannii: How far are we from the truth? / Sacco, F.; Visca, P.; Runci, F.; Antonelli, G.; Raponi, G.. - In: ANTIBIOTICS. - ISSN 2079-6382. - 10:1(2021), pp. 1-12. [10.3390/antibiotics10010048]
File allegati a questo prodotto
File Dimensione Formato  
Sacco_Susceptibility_2021.pdf

accesso aperto

Tipologia: Versione editoriale (versione pubblicata con il layout dell'editore)
Licenza: Tutti i diritti riservati (All rights reserved)
Dimensione 1.32 MB
Formato Adobe PDF
1.32 MB Adobe PDF

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1542807
Citazioni
  • ???jsp.display-item.citation.pmc??? 2
  • Scopus 5
  • ???jsp.display-item.citation.isi??? 4
social impact