Abstract
BackgroundAntibiotic resistance in bacteria leads to massive health problems. Incidence of carbapenem and multidrug resistance in Gram-negative bacteria are increasing globally and turn out to be a very urgent challenge in health care. Resistant bacteria play an important clinical role during hospital outbreaks as well as in sepsis. Rapid diagnostic tests are necessary to provide immediate information for antimicrobial treatment and infection control measures.MethodsOur mass spectrometry-based assay was validated with 63 carbapenemase-producing Gram-negative bacterial isolates, and 35 carbapenem-resistant Gram-negative species with no carbapenemase production. These were analyzed from solid culture media and positive blood culture vials. After 4 h of incubation the carbapenemase products were analyzed with the MALDI-TOF MS. All the isolates were genotyped for carbapenemase genes by PCR and sequencing.ResultsFor culture isolates the concordance of hydrolysis assay to genetic results was 98 % for OXA variants, KPC, VIM, IMP, GIM, and NDM. In contrast, only 14 of 29 Acinetobacter baumannii isolates carrying the OXA and NDM genes could be identified from blood culture. However, from blood culture vials our method allowed the detection of carbapenemases in 98 % of Pseudomonas and Enterobacteriaceae isolates harboring different genes.ConclusionsThis MALDI-TOF MS–based assay permitted the detection of carbapenemases either from solid culture media (98–100 %) or blood culture vials (96 %) for all non-A. baumannii isolates within 4 h. In case of A. baumannii isolates the assay was highly sensitive for the detection of carbapenemases directly from solid culture media.
Highlights
Antibiotic resistance in bacteria leads to massive health problems
MALDI-TOF matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MS) has been performed for the detection of antimicrobial resistance, e.g. β-lactam resistance in Gram-negative bacteria [11, 12]
Imipenem hydrolysis assay A colony of an overnight bacterial culture on MacConkey agar (Becton–Dickinson, Heidelberg, Germany) was washed in 1 ml H2O dest. and centrifuged at 13,200 rpm for 1 min, the harvested pellet was resuspended in 20 mM Tris–HCl, 20 mM NaCl, pH 7.0, to an inoculum equivalent to 3.0 McFarland standard
Summary
Antibiotic resistance in bacteria leads to massive health problems. Incidence of carbapenem and multi‐ drug resistance in Gram-negative bacteria are increasing globally and turn out to be a very urgent challenge in health care. The resistance of bacteria to antibiotics has increased in recent decades. Resistant bacteria can significantly complicate the treatment of infections in critically ill patients; especially in surgery, hemato-oncology, and intensive care in general [1, 2]. The identification and detection of specific resistance mechanisms in these bacteria. MALDI-TOF MS has been performed for the detection of antimicrobial resistance, e.g. β-lactam resistance in Gram-negative bacteria [11, 12]. This method is effective for detection of carbapenemase-producing gram-negative bacteria [9, 12,13,14,15]
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