Detection of carbapenemase activity directly from blood culture vials using MALDI-TOF MS: a quick answer for the right decision.
OBJECTIVE
Recently, matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) was successfully applied for the detection of carbapenemase activity directly from Gram-negative colonies. Based on this principle, we evaluated the performance of MALDI-TOF MS for rapid detection of carbapenemase activity directly from positive blood culture vials.


METHODS
A total of 100 blood culture vials were randomly selected. MALDI-TOF MS carbapenemase assay results were confirmed by the detection of carbapenemase-encoding genes.


RESULTS
A total of 110 bacterial isolates were recovered. The MALDI-TOF MS carbapenemase assay identified 21 of 29 (72.4%) of the carbapenemase-producing isolates directly from the blood culture vials, especially those encoding KPC-2 (100%) and SPM-1 (100%), after a 4 h incubation period. Although the majority of OXA-23-producing Acinetobacter baumannii isolates were not identified on day 1, all isolates were identified as carbapenemase producers directly from the colony on the next day.


CONCLUSIONS
The MALDI-TOF MS carbapenemase assay is a feasible and rapid test to identify carbapenemase activity directly from blood culture vials. It may contribute to faster readjustment of empirical antimicrobial therapy and implementation of infection control measures.
Laboratório Alerta, Disciplina de Infectologia, Departamento de Medicina, Universidade Federal de São Paulo-UNIFESP, São Paulo, SP, Brazil cicacarvalhaes@gmail.com.
Cecilia G
CG
Carvalhaes
Laboratório Alerta, Disciplina de Infectologia, Departamento de Medicina, Universidade Federal de São Paulo-UNIFESP, São Paulo, SP, Brazil.
Rodrigo
R
Cayô
Laboratório Alerta, Disciplina de Infectologia, Departamento de Medicina, Universidade Federal de São Paulo-UNIFESP, São Paulo, SP, Brazil.
Marina F
MF
Visconde
Laboratório Alerta, Disciplina de Infectologia, Departamento de Medicina, Universidade Federal de São Paulo-UNIFESP, São Paulo, SP, Brazil.
Talita
T
Barone
Laboratório Central, Hospital São Paulo, São Paulo, SP, Brazil.
Eliete A M
EA
Frigatto
Departamento de Biofísica, Universidade Federal de São Paulo-UNIFESP, São Paulo, SP, Brazil.
Debora
D
Okamoto
Departamento de Biofísica, Universidade Federal de São Paulo-UNIFESP, São Paulo, SP, Brazil Bruker Daltonics, Atibaia, SP, Brazil.
Diego M
DM
Assis
Departamento de Biofísica, Universidade Federal de São Paulo-UNIFESP, São Paulo, SP, Brazil.
Luiz
L
Juliano
Laboratório Central, Hospital São Paulo, São Paulo, SP, Brazil.
Antonia M O
AM
Machado
Laboratório Alerta, Disciplina de Infectologia, Departamento de Medicina, Universidade Federal de São Paulo-UNIFESP, São Paulo, SP, Brazil.
Ana C
AC
Gales
D040981:Acinetobacter baumannii / Q000201:enzymology / Q000302:isolation & purification; D001426:Bacterial Proteins / Q000097:blood*; D006801:Humans; D007711:Klebsiella pneumoniae / Q000201:enzymology / Q000302:isolation & purification; D011550:Pseudomonas aeruginosa / Q000201:enzymology / Q000302:isolation & purification; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D001618:beta-Lactamases / Q000097:blood*
D001426:Bacterial Proteins; C491478:beta-lactamase KPC-2; C466679:beta-lactamase OXA-23; C476155:beta-lactamase SPM-1, Pseudomonas aeruginosa; D001618:beta-Lactamases; C063912:carbapenemase
KPC; OXA-type; metallo-β-lactamases; oxacillinases; serine-β-lactamases