Validation of a novel automatic deposition of bacteria and yeasts on MALDI target for MALDI-TOF MS-based identification using MALDI Colonyst robot

<div><p>Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) -based identification of bacteria and fungi significantly changed the diagnostic process in clinical microbiology. We describe here a novel technique for bacterial and yeast deposition on MALDI target using an automated workflow resulting in an increase of the microbes’ score of MALDI identification. We also provide a comparison of four different sample preparation methods. In the first step of the study, 100 Gram-negative bacteria, 100 Gram-positive bacteria, 20 anaerobic bacteria and 20 yeasts were spotted on the MALDI target using manual deposition, semi-extraction, wet deposition onto 70% formic acid and by automatic deposition using MALDI Colonyst. The lowest scores were obtained by manual toothpick spotting which significantly differ from other methods. Identification score of semi-extraction, wet deposition and automatic wet deposition did not significantly differ using calculated relative standard deviation (RSD). Nevertheless, the best results with low error rate have been observed using MALDI Colonyst robot. The second step of validation included processing of 542 clinical isolates in routine microbiological laboratory by a toothpick direct spotting, on-plate formic acid extraction (for yeasts) and automatic deposition using MALDI Colonyst. Validation in routine laboratory process showed significantly higher identification scores obtained using automated process compared with standard manual deposition in all tested microbial groups (Gram-positive, Gram-negative, anaerobes, and yeasts). As shown by our data, automatic colony deposition on MALDI target results in an increase of MALDI-TOF MS identification scores and reproducibility.</p></div

Identification score of microbes processed by four different methods of deposition on MALDI target.

<p>Identification score of microbes processed by four different methods of deposition on MALDI target.</p

Comparison of identification scores in the second stage of the study.

<p>Routine clinical samples were identified by direct spotting or semi-extraction (yeasts) and by automatic deposition using MALDI Colonyst from the same culture.</p

Comparison of different deposition methods with plotted RSD.

<p>Statistically significant differences are indicated by asterisks.</p

Repeatibility of automatic bacterial deposition using MALDI Colonyst determined by standard deviation (SD) and relative standard deviation (RSD%).

<p>Each strain was spotted ten times from the same culture plate and identified using MALDI-TOF MS.</p

Presentation_2_Implication of different replicons in the spread of the VIM-1-encoding integron, In110, in Enterobacterales from Czech hospitals.PPTX

BackgroundVIM metallo-β-lactamases are enzymes characterized by the ability to hydrolyze all β-lactams. Usually, blaVIM-like genes are carried by class 1 integrons. In the Czech Republic, only sporadic cases of VIM-producing Enterobacterales have been reported in which those isolates carried the VIM-1 carbapenemase-encoding integron In110. However, during 2019–2020, an increased number was reported. Therefore, the aim of the current study was to characterize the genetic elements involved in the increased spread of blaVIM genes.Materials and methods32 VIM-producing Enterobacterales collected between 2019 and 2020 were subjected to: antimicrobial susceptibility testing, integron analysis, and short reads sequencing. Based on the results, 19 isolates were selected as representative and sequenced using Sequel I platform.ResultsThe 32 VIM-producing isolates exhibited variations in the MICs of carbapenems. Based on short-read data, 26 of the 32 sequenced isolates harbored the blaVIM-1 allele while six isolates carried the blaVIM-4 gene. The most prevalent was the In110 integron (n = 24) and two isolates carried the In4873 class 1 integron. The blaVIM-4 allele was identified in class 1 integrons In1174 (n = 3), In416 (n = 1), In2143 (n = 1) and In2150. Long reads sequencing revealed that the blaVIM was carried by: pKPC-CAV1193-like (n = 6), HI1 (pNDM-CIT; n = 4), HI2 (n = 3), FIB (pECLA; n = 2) and N (n = 1) incompatibility groups. Two blaVIM-carrying plasmids could not be typed by the database, while another one was integrated into the chromosome.ConclusionWe observed the spread of VIM-encoding integrons, mainly of In110, among Enterobacterales isolated from Czech hospitals, but also an increased number of novel elements underlining the ongoing evolution.</p

Presentation_6_Implication of different replicons in the spread of the VIM-1-encoding integron, In110, in Enterobacterales from Czech hospitals.PPTX

BackgroundVIM metallo-β-lactamases are enzymes characterized by the ability to hydrolyze all β-lactams. Usually, blaVIM-like genes are carried by class 1 integrons. In the Czech Republic, only sporadic cases of VIM-producing Enterobacterales have been reported in which those isolates carried the VIM-1 carbapenemase-encoding integron In110. However, during 2019–2020, an increased number was reported. Therefore, the aim of the current study was to characterize the genetic elements involved in the increased spread of blaVIM genes.Materials and methods32 VIM-producing Enterobacterales collected between 2019 and 2020 were subjected to: antimicrobial susceptibility testing, integron analysis, and short reads sequencing. Based on the results, 19 isolates were selected as representative and sequenced using Sequel I platform.ResultsThe 32 VIM-producing isolates exhibited variations in the MICs of carbapenems. Based on short-read data, 26 of the 32 sequenced isolates harbored the blaVIM-1 allele while six isolates carried the blaVIM-4 gene. The most prevalent was the In110 integron (n = 24) and two isolates carried the In4873 class 1 integron. The blaVIM-4 allele was identified in class 1 integrons In1174 (n = 3), In416 (n = 1), In2143 (n = 1) and In2150. Long reads sequencing revealed that the blaVIM was carried by: pKPC-CAV1193-like (n = 6), HI1 (pNDM-CIT; n = 4), HI2 (n = 3), FIB (pECLA; n = 2) and N (n = 1) incompatibility groups. Two blaVIM-carrying plasmids could not be typed by the database, while another one was integrated into the chromosome.ConclusionWe observed the spread of VIM-encoding integrons, mainly of In110, among Enterobacterales isolated from Czech hospitals, but also an increased number of novel elements underlining the ongoing evolution.</p

Presentation_9_Implication of different replicons in the spread of the VIM-1-encoding integron, In110, in Enterobacterales from Czech hospitals.PPTX

BackgroundVIM metallo-β-lactamases are enzymes characterized by the ability to hydrolyze all β-lactams. Usually, blaVIM-like genes are carried by class 1 integrons. In the Czech Republic, only sporadic cases of VIM-producing Enterobacterales have been reported in which those isolates carried the VIM-1 carbapenemase-encoding integron In110. However, during 2019–2020, an increased number was reported. Therefore, the aim of the current study was to characterize the genetic elements involved in the increased spread of blaVIM genes.Materials and methods32 VIM-producing Enterobacterales collected between 2019 and 2020 were subjected to: antimicrobial susceptibility testing, integron analysis, and short reads sequencing. Based on the results, 19 isolates were selected as representative and sequenced using Sequel I platform.ResultsThe 32 VIM-producing isolates exhibited variations in the MICs of carbapenems. Based on short-read data, 26 of the 32 sequenced isolates harbored the blaVIM-1 allele while six isolates carried the blaVIM-4 gene. The most prevalent was the In110 integron (n = 24) and two isolates carried the In4873 class 1 integron. The blaVIM-4 allele was identified in class 1 integrons In1174 (n = 3), In416 (n = 1), In2143 (n = 1) and In2150. Long reads sequencing revealed that the blaVIM was carried by: pKPC-CAV1193-like (n = 6), HI1 (pNDM-CIT; n = 4), HI2 (n = 3), FIB (pECLA; n = 2) and N (n = 1) incompatibility groups. Two blaVIM-carrying plasmids could not be typed by the database, while another one was integrated into the chromosome.ConclusionWe observed the spread of VIM-encoding integrons, mainly of In110, among Enterobacterales isolated from Czech hospitals, but also an increased number of novel elements underlining the ongoing evolution.</p

Presentation_5_Implication of different replicons in the spread of the VIM-1-encoding integron, In110, in Enterobacterales from Czech hospitals.PPTX

BackgroundVIM metallo-β-lactamases are enzymes characterized by the ability to hydrolyze all β-lactams. Usually, blaVIM-like genes are carried by class 1 integrons. In the Czech Republic, only sporadic cases of VIM-producing Enterobacterales have been reported in which those isolates carried the VIM-1 carbapenemase-encoding integron In110. However, during 2019–2020, an increased number was reported. Therefore, the aim of the current study was to characterize the genetic elements involved in the increased spread of blaVIM genes.Materials and methods32 VIM-producing Enterobacterales collected between 2019 and 2020 were subjected to: antimicrobial susceptibility testing, integron analysis, and short reads sequencing. Based on the results, 19 isolates were selected as representative and sequenced using Sequel I platform.ResultsThe 32 VIM-producing isolates exhibited variations in the MICs of carbapenems. Based on short-read data, 26 of the 32 sequenced isolates harbored the blaVIM-1 allele while six isolates carried the blaVIM-4 gene. The most prevalent was the In110 integron (n = 24) and two isolates carried the In4873 class 1 integron. The blaVIM-4 allele was identified in class 1 integrons In1174 (n = 3), In416 (n = 1), In2143 (n = 1) and In2150. Long reads sequencing revealed that the blaVIM was carried by: pKPC-CAV1193-like (n = 6), HI1 (pNDM-CIT; n = 4), HI2 (n = 3), FIB (pECLA; n = 2) and N (n = 1) incompatibility groups. Two blaVIM-carrying plasmids could not be typed by the database, while another one was integrated into the chromosome.ConclusionWe observed the spread of VIM-encoding integrons, mainly of In110, among Enterobacterales isolated from Czech hospitals, but also an increased number of novel elements underlining the ongoing evolution.</p

Presentation_7_Implication of different replicons in the spread of the VIM-1-encoding integron, In110, in Enterobacterales from Czech hospitals.PPTX

BackgroundVIM metallo-β-lactamases are enzymes characterized by the ability to hydrolyze all β-lactams. Usually, blaVIM-like genes are carried by class 1 integrons. In the Czech Republic, only sporadic cases of VIM-producing Enterobacterales have been reported in which those isolates carried the VIM-1 carbapenemase-encoding integron In110. However, during 2019–2020, an increased number was reported. Therefore, the aim of the current study was to characterize the genetic elements involved in the increased spread of blaVIM genes.Materials and methods32 VIM-producing Enterobacterales collected between 2019 and 2020 were subjected to: antimicrobial susceptibility testing, integron analysis, and short reads sequencing. Based on the results, 19 isolates were selected as representative and sequenced using Sequel I platform.ResultsThe 32 VIM-producing isolates exhibited variations in the MICs of carbapenems. Based on short-read data, 26 of the 32 sequenced isolates harbored the blaVIM-1 allele while six isolates carried the blaVIM-4 gene. The most prevalent was the In110 integron (n = 24) and two isolates carried the In4873 class 1 integron. The blaVIM-4 allele was identified in class 1 integrons In1174 (n = 3), In416 (n = 1), In2143 (n = 1) and In2150. Long reads sequencing revealed that the blaVIM was carried by: pKPC-CAV1193-like (n = 6), HI1 (pNDM-CIT; n = 4), HI2 (n = 3), FIB (pECLA; n = 2) and N (n = 1) incompatibility groups. Two blaVIM-carrying plasmids could not be typed by the database, while another one was integrated into the chromosome.ConclusionWe observed the spread of VIM-encoding integrons, mainly of In110, among Enterobacterales isolated from Czech hospitals, but also an increased number of novel elements underlining the ongoing evolution.</p