The resistance to carbapenems is usually mediated by enzymes hydrolyzing β-lactam ring. Recently, an alternative way of the modification of the antibiotic, a β-lactone formation by OXA-48-like enzymes, in some carbapenems was identified. We focused our study on a deep analysis of OXA-48-like-producing Enterobacterales, especially strains showing poor hydrolytic activity. In this study, well characterized 74 isolates of Enterobacterales resistant to carbapenems were used. Carbapenemase activity was determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), liquid chromatography/mass spectrometry (LC-MS), Carba-NP test and modified Carbapenem Inactivation Method (mCIM). As meropenem-derived β-lactone possesses the same molecular weight as native meropenem (MW 383.46 g/mol), β-lactonization cannot be directly detected by MALDI-TOF MS. In the spectra, however, the peaks of m/z = 340.5 and 362.5 representing decarboxylated β-lactone and its sodium adduct were detected in 25 out of 35 OXA-48-like producers. In the rest 10 isolates, decarboxylated hydrolytic product (m/z = 358.5) and its sodium adduct (m/z = 380.5) have been detected. The peak of m/z = 362.5 was detected in 3 strains co-producing OXA-48-like and NDM-1 carbapenemases. The respective signal was identified in no strain producing class A or class B carbapenemase alone showing its specificity for OXA-48-like carbapenemases. Using LC-MS, we were able to identify meropenem-derived β-lactone directly according to the different retention time. All strains with a predominant β-lactone production showed negative results of Carba NP test. In this study, we have demonstrated that the strains producing OXA-48-like carbapenemases showing false-negative results using Carba NP test and MALDI-TOF MS preferentially produced meropenem-derived β-lactone. We also identified β-lactone-specific peak in MALDI-TOF MS spectra and demonstrated the ability of LC-MS to detect meropenem-derived β-lactone.

• MeSH
• antibakteriální látky farmakologie   MeSH
• bakteriální proteiny * analýza   MeSH
• beta-laktamasy analýza   MeSH
• Enterobacteriaceae * MeSH
• karbapenemy farmakologie   MeSH
• meropenem farmakologie   MeSH
• mikrobiální testy citlivosti MeSH
• spektrometrie hmotnostní - ionizace laserem za účasti matrice metody   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antibakteriální látky MeSH
• bakteriální proteiny * MeSH
• beta-laktamasy MeSH
• carbapenemase MeSH Prohlížeč
• karbapenemy MeSH
• meropenem MeSH

The aim of the present study is to describe the ongoing spread of the KPC-producing strains, which is evolving to an epidemic in Czech hospitals. During the period of 2018-2019, a total of 108 KPC-producing Enterobacterales were recovered from 20 hospitals. Analysis of long-read sequencing data revealed the presence of several types of blaKPC-carrying plasmids; 19 out of 25 blaKPC-carrying plasmids could be assigned to R (n = 12), N (n = 5), C (n = 1) and P6 (n = 1) incompatibility (Inc) groups. Five of the remaining blaKPC-carrying plasmids were multireplicon, while one plasmid couldn't be typed. Additionally, phylogenetic analysis confirmed the spread of blaKPC-carrying plasmids among different clones of diverse Enterobacterales species. Our findings demonstrated that the increased prevalence of KPC-producing isolates was due to plasmids spreading among different species. In some districts, the local dissemination of IncR and IncN plasmids was observed. Additionally, the ongoing evolution of blaKPC-carrying plasmids, through genetic rearrangements, favours the preservation and further dissemination of these mobile genetic elements. Therefore, the situation should be monitored, and immediate infection control should be implemented in hospitals reporting KPC-producing strains.

• MeSH
• antibakteriální látky farmakologie   MeSH
• bakteriální léková rezistence * MeSH
• bakteriální proteiny genetika   metabolismus   MeSH
• beta-laktamasy metabolismus   MeSH
• epidemie MeSH
• infekce bakteriemi rodu Klebsiella epidemiologie   mikrobiologie   MeSH
• Klebsiella pneumoniae izolace a purifikace   metabolismus   MeSH
• lidé MeSH
• nemocnice statistika a číselné údaje   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika epidemiologie   MeSH
• Názvy látek
• antibakteriální látky MeSH
• bakteriální proteiny MeSH
• beta-laktamasy MeSH
• carbapenemase MeSH Prohlížeč

Ten Enterobacteriaceae isolates collected in a Czech hospital carried blaKPC-positive plasmids of different sizes (∼30, ∼45, and ∼80 kb). Sequencing revealed three types of plasmids (A to C) with the Tn4401a transposon. Type A plasmids comprised an IncR backbone and a KPC-2-encoding multidrug resistance (MDR) region. Type B plasmids were derivatives of type A plasmids carrying an IncN3-like segment, while type C plasmids were IncP6 plasmids sharing the same KPC-2-encoding MDR region with type A and B plasmids.

• Klíčová slova
• Citrobacter freundii, Illumina sequencing, IncR, ST18, Tn4401a,
• MeSH
• antibakteriální látky terapeutické užití   MeSH
• beta-laktamasy genetika   metabolismus   MeSH
• Citrobacter freundii účinky léků   enzymologie   genetika   izolace a purifikace   MeSH
• enterobakteriální infekce farmakoterapie   epidemiologie   mikrobiologie   MeSH
• Escherichia coli účinky léků   enzymologie   genetika   izolace a purifikace   MeSH
• exprese genu MeSH
• izoenzymy genetika   metabolismus   MeSH
• karbapenemy terapeutické užití   MeSH
• Klebsiella pneumoniae účinky léků   enzymologie   genetika   izolace a purifikace   MeSH
• lidé MeSH
• mikrobiální testy citlivosti MeSH
• mnohočetná bakteriální léková rezistence genetika   MeSH
• Morganella morganii účinky léků   enzymologie   genetika   izolace a purifikace   MeSH
• nemocnice MeSH
• otevřené čtecí rámce MeSH
• plazmidy chemie   klasifikace   metabolismus   MeSH
• sekvence nukleotidů MeSH
• sekvenční analýza DNA MeSH
• transpozibilní elementy DNA MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika epidemiologie   MeSH
• Názvy látek
• antibakteriální látky MeSH
• beta-lactamase KPC-2 MeSH Prohlížeč
• beta-laktamasy MeSH
• izoenzymy MeSH
• karbapenemy MeSH
• transpozibilní elementy DNA MeSH

The aim of this study was to characterize the first cases and outbreaks of OXA-48-like-producing Enterobacteriaceae recovered from hospital settings in the Czech Republic. From 2013 to 2015, 22 Klebsiella pneumoniae isolates, 3 Escherichia coli isolates, and 1 Enterobacter cloacae isolate producing OXA-48-like carbapenemases were isolated from 20 patients. Four of the patients were colonized or infected by two or three different OXA-48-like producers. The K. pneumoniae isolates were classified into nine sequence types (STs), with ST101 being predominant (n = 8). The E. coli isolates were of different STs, while the E. cloacae isolate belonged to ST109. Twenty-four isolates carried blaOXA-48, while two isolates carried blaOXA-181 or blaOXA-232 Almost all isolates (n = 22) carried blaOXA-48-positive plasmids of a similar size (∼60 kb), except the two isolates producing OXA-181 or OXA-232. In an ST45 K. pneumoniae isolate and an ST38 E. coli isolate, S1 nuclease profiling plus hybridization indicated a chromosomal location of blaOXA-48 Sequencing showed that the majority of blaOXA-48-carrying plasmids exhibited high degrees of identity with the pOXA-48-like plasmid pE71T. Additionally, two novel pE71T derivatives, pOXA-48_30715 and pOXA-48_30891, were observed. The blaOXA-181-carrying plasmid was identical to the IncX3 plasmid pOXA181_EC14828, while the blaOXA-232-carrying plasmid was a ColE2-type plasmid, being a novel derivative of pOXA-232. Finally, sequencing data showed that the ST45 K. pneumoniae and ST38 E. coli isolates harbored the IS1R-based composite transposon Tn6237 containing blaOXA-48 integrated into their chromosomes. These findings underlined that the horizontal transfer of pOXA-48-like plasmids has played a major role in the dissemination of blaOXA-48 in the Czech Republic. In combination with the difficulties with their detection, OXA-48 producers constitute an important public threat.

• Klíčová slova
• ColE2-like, IncL, IncX3, Klebsiella pneumoniae, OXA-181, OXA-232, Tn1999.2, Tn1999.5,
• MeSH
• antibakteriální látky farmakologie   MeSH
• bakteriální chromozomy genetika   MeSH
• bakteriální proteiny genetika   metabolismus   MeSH
• beta-laktamasy genetika   metabolismus   MeSH
• Enterobacteriaceae účinky léků   enzymologie   genetika   MeSH
• Escherichia coli účinky léků   enzymologie   genetika   MeSH
• Klebsiella pneumoniae účinky léků   enzymologie   genetika   MeSH
• mikrobiální testy citlivosti MeSH
• plazmidy genetika   MeSH
• přenos genů horizontální genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Česká republika MeSH
• Názvy látek
• antibakteriální látky MeSH
• bakteriální proteiny MeSH
• beta-laktamasy MeSH
• carbapenemase MeSH Prohlížeč

Carbapenemase-mediated resistance to carbapenems in Enterobacteriaceae has become the main challenge in the treatment and prevention of infections recently. The partially unnoticed spread of OXA-48-type carbapenemase producers is usually assigned to low minimum inhibitory concentrations (MICs) of carbapenems that OXA-48-producing isolates often display. Therefore, there is an urgent need of specific and sensitive methods for isolation and detection of OXA-48 producers in clinical microbiology diagnostics. The influence of bicarbonates on carbapenem MICs against carbapenemase-producing Enterobacteriaceae was tested. We also checked whether the addition of bicarbonates to liquid media supplemented with meropenem may facilitate the selective enrichment of various carbapenemase producers in cultures. Furthermore, the sensitivity of carbapenemase confirmation by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF MS) and spectrophotometric hydrolysis assays upon the addition of NH4HCO3 was examined. The addition of NaHCO3 significantly increased MICs of ertapenem and meropenem for OXA-48 producers. Furthermore, liquid media supplemented with NaHCO3 and meropenem were reliable for the selective enrichment of carbapenemase producers. The presence of NH4HCO3 in buffers used in the spectrophotometric and MALDI-TOF MS carbapenemase detection increased the sensitivity of that assay. Our results demonstrate that bicarbonates in media or reaction buffers can enhance the sensitivity of screening methods and diagnostic tests for carbapenemase producers.

• MeSH
• bakteriální proteiny analýza   metabolismus   MeSH
• beta-laktamasy analýza   metabolismus   MeSH
• Enterobacteriaceae enzymologie   izolace a purifikace   MeSH
• enterobakteriální infekce diagnóza   mikrobiologie   MeSH
• hydrogenuhličitany * MeSH
• kultivační média chemie   MeSH
• mikrobiální testy citlivosti metody   MeSH
• pufry MeSH
• senzitivita a specificita MeSH
• spektrometrie hmotnostní - ionizace laserem za účasti matrice MeSH
• Publikační typ
• časopisecké články MeSH
• hodnotící studie MeSH
• práce podpořená grantem MeSH
• Názvy látek
• bakteriální proteiny MeSH
• beta-laktamasy MeSH
• carbapenemase MeSH Prohlížeč
• hydrogenuhličitany * MeSH
• kultivační média MeSH
• pufry MeSH

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has been successfully applied as an identification procedure in clinical microbiology and has been widely used in routine laboratory practice because of its economical and diagnostic benefits. The range of applications of MALDI-TOF MS has been growing constantly, from rapid species identification to labor-intensive proteomic studies of bacterial physiology. The purpose of this review is to summarize the contribution of the studies already performed with MALDI-TOF MS concerning antibiotic resistance and to analyze future perspectives in this field. We believe that current research should continue in four main directions, including the detection of antibiotic modifications by degrading enzymes, the detection of resistance mechanism determinants through proteomic studies of multiresistant bacteria, and the analysis of modifications of target sites, such as ribosomal methylation. The quantification of antibiotics is suggested as a new approach to study influx and efflux in bacterial cells. The results of the presented studies demonstrate that MALDI-TOF MS is a relevant tool for the detection of antibiotic resistance and opens new avenues for both clinical and experimental microbiology.

• MeSH
• antibakteriální látky farmakologie   MeSH
• Bacteria účinky léků   MeSH
• bakteriální léková rezistence * MeSH
• biomedicínský výzkum trendy   MeSH
• mikrobiální testy citlivosti metody   MeSH
• spektrometrie hmotnostní - ionizace laserem za účasti matrice metody   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• antibakteriální látky MeSH

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is a potentially useful tool for the detection of antimicrobial resistance, especially that conferred by β-lactamases. Here we describe a modification of a previously reported MALDI-TOF MS meropenem hydrolysis assay. The modified method was validated on 108 carbapenemase-producing members of the Enterobacteriaceae, two NDM-1-producing Acinetobacter baumannii isolates, and 35 carbapenem-resistant enterobacteria producing no carbapenemase. The detection of carbapenemases by MALDI-TOF MS seems to be a powerful, quick, and cost-effective method for microbiological laboratories.

• MeSH
• Acinetobacter baumannii enzymologie   MeSH
• bakteriální proteiny metabolismus   MeSH
• beta-laktamasy metabolismus   MeSH
• Enterobacteriaceae enzymologie   MeSH
• enterobakteriální infekce mikrobiologie   MeSH
• hydrolýza MeSH
• lidé MeSH
• meropenem MeSH
• mikrobiální testy citlivosti metody   MeSH
• spektrometrie hmotnostní - ionizace laserem za účasti matrice metody   MeSH
• thienamyciny metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• validační studie MeSH
• Názvy látek
• bakteriální proteiny MeSH
• beta-laktamasy MeSH
• carbapenemase MeSH Prohlížeč
• meropenem MeSH
• thienamyciny MeSH

Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry is used for the determination of molecular weights of different chemical compounds. We describe here the use of MALDI-TOF mass spectrometry to detect a carbapenem antibiotic, meropenem, and its degradation products. Buffered meropenem solution (0.1 mM Tris-HCl, pH 6.8) was mixed with an overnight culture of bacteria. After 3-h incubation, the reaction mixture was centrifuged, and the supernatant was analyzed by MALDI-TOF mass spectrometry. The presence or absence of peaks representing meropenem and its sodium salts was crucial. The average turnaround time of this test, considering the use of overnight culture, is 4 h. We validated this method for the detection of resistance to carbapenems in Enterobacteriaceae and Pseudomonas aeruginosa mediated by carbapenemase production. A total of 124 strains, including 30 carbapenemase-producing strains, were used in the study. The sensitivity of this method is 96.67%, with a specificity of 97.87%. Our results demonstrate the ability of this method to routinely detect carbapenemases in Enterobacteriaceae and Pseudomonas spp. in laboratories. This assay is comparable with a labor-intensive imipenem-hydrolyzing spectrophotometric assay that is a reference method for the detection of carbapenemase. As demonstrated here, MALDI-TOF mass spectrometry may be used in microbiological laboratories not only for microbial identification but also for other applications, such as studies of mechanisms of antibiotic resistance.

• MeSH
• antibakteriální látky analýza   MeSH
• bakteriální proteiny metabolismus   MeSH
• beta-laktamasy metabolismus   MeSH
• Enterobacteriaceae enzymologie   MeSH
• lidé MeSH
• meropenem MeSH
• Pseudomonas aeruginosa enzymologie   MeSH
• senzitivita a specificita MeSH
• spektrometrie hmotnostní - ionizace laserem za účasti matrice metody   MeSH
• thienamyciny analýza   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• hodnotící studie MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antibakteriální látky MeSH
• bakteriální proteiny MeSH
• beta-laktamasy MeSH
• carbapenemase MeSH Prohlížeč
• meropenem MeSH
• thienamyciny MeSH