scholarly journals Rapid Induction of High-Level Carbapenem Resistance in Heteroresistant KPC-Producing Klebsiella pneumoniae

2015 ◽  
Vol 59 (6) ◽  
pp. 3281-3289 ◽  
Author(s):  
Sheila Adams-Sapper ◽  
Shantell Nolen ◽  
Grace Fox Donzelli ◽  
Mallika Lal ◽  
Kunihiko Chen ◽  
...  

ABSTRACTEnterobacteriaceaestrains producing theKlebsiella pneumoniaecarbapenemase (KPC) have disseminated worldwide, causing an urgent threat to public health. KPC-producing strains often exhibit low-level carbapenem resistance, which may be missed by automated clinical detection systems. In this study, eightKlebsiella pneumoniaestrains with heterogeneous resistance to imipenem were used to elucidate the factors leading from imipenem susceptibility to high-level resistance as defined by clinical laboratory testing standards. Time-kill analysis with an inoculum as low as 3 × 106CFU/ml and concentrations of imipenem 8- and 16-fold higher than the MIC resulted in the initial killing of 99.9% of the population. However, full recovery of the population occurred by 20 h of incubation in the same drug concentrations. Population profiles showed that recovery was mediated by a heteroresistant subpopulation at a frequency of 2 × 10−7to 3 × 10−6. Samples selected 2 h after exposure to imipenem were as susceptible as the unexposed parental strain and produced the major outer membrane porin OmpK36. However, between 4 to 8 h after exposure, OmpK36 became absent, and the imipenem MIC increased at least 32-fold. Individual colonies isolated from cultures after 20 h of exposure revealed both susceptible and resistant subpopulations. Once induced, however, the high-level imipenem resistance was maintained, and OmpK36 remained unexpressed even without continued carbapenem exposure. This study demonstrates the essential coordination betweenblaKPCandompK36expression mediating high-level imipenem resistance from a population of bacteria that initially exhibits a carbapenem-susceptibility phenotype.

2018 ◽  
Vol 62 (10) ◽  
Author(s):  
Johanne Blais ◽  
Sara Lopez ◽  
Cindy Li ◽  
Alexey Ruzin ◽  
Srijan Ranjitkar ◽  
...  

ABSTRACTLYS228 is a novel monobactam with potent activity againstEnterobacteriaceae. LYS228 is stable to metallo-β-lactamases (MBLs) and serine carbapenemases, includingKlebsiella pneumoniaecarbapenemases (KPCs), resulting in potency against the majority of extended-spectrum β-lactamase (ESBL)-producing and carbapenem-resistantEnterobacteriaceaestrains tested. Overall, LYS228 demonstrated potent activity against 271Enterobacteriaceaestrains, including multidrug-resistant isolates. Based on MIC90values, LYS228 (MIC90, 1 μg/ml) was ≥32-fold more active against those strains than were aztreonam, ceftazidime, ceftazidime-avibactam, cefepime, and meropenem. The tigecycline MIC90was 4 μg/ml against the strains tested. AgainstEnterobacteriaceaeisolates expressing ESBLs (n= 37) or displaying carbapenem resistance (n= 77), LYS228 had MIC90values of 1 and 4 μg/ml, respectively. LYS228 exhibited potent bactericidal activity, as indicated by low minimal bactericidal concentration (MBC) to MIC ratios (MBC/MIC ratios of ≤4) against 97.4% of theEnterobacteriaceaestrains tested (264/271 strains). In time-kill studies, LYS228 consistently achieved reductions in CFU per milliliter of 3 log10units (≥99.9% killing) at concentrations ≥4× MIC forEscherichia coliandK. pneumoniaereference strains, as well as isolates encoding TEM-1, SHV-1, CTX-M-14, CTX-M-15, KPC-2, KPC-3, and NDM-1 β-lactamases.


2018 ◽  
Vol 62 (11) ◽  
Author(s):  
Peijun Ma ◽  
Hannah H. Laibinis ◽  
Christoph M. Ernst ◽  
Deborah T. Hung

ABSTRACT Carbapenem resistance is mainly mediated by carbapenemases or extended-spectrum β-lactamases (ESBL) plus a loss of porins. However, we have identified a Klebsiella pneumoniae clinical isolate that contains neither carbapenemases nor ESBLs. Instead, we found that high-level expression of a novel blaOXA-10-derived β-lactamase gene, blaOXA-663, in conjunction with OmpK36 deficiency results in high-level carbapenem resistance. This finding demonstrates the combinatorial complexity of factors, including β-lactamase activity, its expression levels, and porin activity, that yield carbapenem resistance.


2015 ◽  
Vol 59 (9) ◽  
pp. 5793-5797 ◽  
Author(s):  
Ryan K. Shields ◽  
Cornelius J. Clancy ◽  
Binghua Hao ◽  
Liang Chen ◽  
Ellen G. Press ◽  
...  

ABSTRACTAvibactam is a novel β-lactamase inhibitor with affinity forKlebsiella pneumoniaecarbapenemases (KPCs). In combination with ceftazidime, the agent demonstrates activity against KPC-producingK. pneumoniae(KPC-Kp). KPC-Kp strains are genetically diverse and harbor multiple resistance determinants, including defects in outer membrane proteins and extended-spectrum β-lactamases (ESBLs). Mutations in porin geneompK36confer high-level carbapenem resistance to KPC-Kp strains. Whether specific mechanisms of antimicrobial resistance also influence the activity of ceftazidime-avibactam is unknown. We defined the effects of ceftazidime-avibactam against 72 KPC-Kp strains with diverse mechanisms of resistance, including various combinations of KPC subtypes and ESBL andompK36mutations. Ceftazidime MICs ranged from 64 to 4,096 μg/ml and were lowered by a median of 512-fold with the addition of avibactam. All strains exhibited ceftazidime-avibactam MICs at or below the CLSI breakpoint for ceftazidime (≤4 μg/ml; range, 0.25 to 4). However, the MICs were within two 2-fold dilutions of the CLSI breakpoint against 24% of the strains, and those strains would be classified as nonsusceptible to ceftazidime by EUCAST criteria (MIC > 1 μg/ml). Median ceftazidime-avibactam MICs were higher against KPC-3 than KPC-2 variants (P= 0.02). Among KPC-2-Kp strains, the presence of both ESBL and porin mutations was associated with higher drug MICs compared to those seen with either factor alone (P= 0.003 andP= 0.02, respectively). In conclusion, ceftazidime-avibactam displays activity against genetically diverse KPC-Kp strains. Strains with higher-level drug MICs provide a reason for caution. Judicious use of ceftazidime-avibactam alone or in combination with other agents will be important to prevent the emergence of resistance.


2013 ◽  
Vol 57 (5) ◽  
pp. 2147-2153 ◽  
Author(s):  
Jae H. Hong ◽  
Cornelius J. Clancy ◽  
Shaoji Cheng ◽  
Ryan K. Shields ◽  
Liang Chen ◽  
...  

ABSTRACTWe characterized carbapenem resistance mechanisms among 12Klebsiella pneumoniaecarbapenemase (KPC)-producingK. pneumoniae(referred to here as KPCK. pneumoniae) clinical isolates and evaluated their effects on the activity of 2- and 3-drug combinations of colistin, doripenem, and ertapenem. All isolates were resistant to ertapenem and doripenem; 75% (9/12) were resistant to colistin. Isolates belonged to the ST258 clonal group and harboredblaKPC-2,blaSHV-12, andblaTEM-1. As determined by time-kill assays, doripenem (8 μg/ml) and ertapenem (2 μg/ml) were inactive against 92% (11/12) and 100% (12/12) of isolates, respectively. Colistin (2.5 μg/ml) exerted some activity (range, 0.39 to 2.5 log10) against 78% (7/9) of colistin-resistant isolates. Colistin-ertapenem, colistin-doripenem, and colistin-doripenem-ertapenem exhibited synergy against 42% (5/12), 50% (6/12), and 67% (8/12) of isolates, respectively. Expression ofompK35andompK36porins correlated with each other (R2= 0.80). Levels of porin expression did not correlate with colistin-doripenem or colistin-ertapenem synergy. However, synergy with colistin-doripenem-ertapenem was more likely against isolates with high porin expression than those with low expression (100% [8/8] versus 0% [0/4];P= 0.002). Moreover, bactericidal activity (area under the bacterial killing curve) against isolates with high porin expression was greater for colistin-doripenem-ertapenem than colistin-doripenem or colistin-ertapenem (P≤ 0.049). In conclusion, colistin-carbapenem combinations may provide optimal activity against KPCK. pneumoniae, including colistin-resistant isolates. Screening for porin expression may identify isolates that are most likely to respond to a triple combination of colistin-doripenem-ertapenem. In the future, molecular characterization of KPCK. pneumoniaeisolates may be a practical tool for identifying effective combination regimens.


2019 ◽  
Vol 64 (1) ◽  
Author(s):  
Alina Iovleva ◽  
Roberta T. Mettus ◽  
Christi L. McElheny ◽  
Marissa P. Griffith ◽  
Mustapha M. Mustapha ◽  
...  

ABSTRACT OXA-232 is an OXA-48-group class D β-lactamase that hydrolyzes expanded-spectrum cephalosporins and carbapenems at low levels. Clinical strains producing OXA-232 are sometimes susceptible to carbapenems, making it difficult to identify them in the clinical microbiology laboratory. We describe the development of carbapenem resistance in sequential clinical isolates of Raoultella ornithinolytica carrying blaOXA-232 in a hospitalized patient, where the ertapenem MIC increased from 0.5 μg/ml to 512 μg/ml and the meropenem MIC increased from 0.125 μg/ml to 32 μg/ml during the course of ertapenem therapy. Whole-genome sequencing (WGS) analysis identified loss-of-function mutations in ompC and ompF in carbapenem-resistant isolates that were not present in the initial carbapenem-susceptible isolate. Complementation of a carbapenem-resistant isolate with an intact ompF gene resulted in 16- to 32-fold reductions in carbapenem MICs, whereas complementation with intact ompC resulted in a 2-fold reduction in carbapenem MICs. Additionally, blaOXA-232 expression increased 2.9-fold in a carbapenem-resistant isolate. Rapid development of high-level carbapenem resistance in initially carbapenem-susceptible OXA-232-producing R. ornithinolytica under selective pressure from carbapenem therapy highlights the diagnostic challenges in detecting Enterobacteriaceae strains producing this inefficient carbapenemase.


Antibiotics ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 1174
Author(s):  
Pilar Lumbreras-Iglesias ◽  
M. Rosario Rodicio ◽  
Pablo Valledor ◽  
Tomás Suárez-Zarracina ◽  
Javier Fernández

The aim of this work was to analyze outer membrane porin-encoding genes (ompK35 and ompK36) in a collection of OXA-48 producing Klebsiella pneumoniae, to assess the effect of porin alterations on the susceptibility to ceftazidime/avibactam, and to describe a screening methodology for phenotypic detection of OXA-48-producing K. pneumoniae with disrupted porins. Antimicrobial susceptibility was tested by Microscan and Etest. The genomes of 81 OXA-48-producing K. pneumoniae were sequenced. MLST, detection of antimicrobial resistance genes, and analysis of ompK35 and ompK36 were performed in silico. Tridimensional structures of the OmpK36 variants were assessed. Receiver operating characteristics curves were built to visualize the performance ability of a disk diffusion assay using carbapenems and cefoxitin to detect OmpK36 functional alterations. A wide variety of OmpK36 alterations were detected in 17 OXA-48-producing K. pneumoniae isolates. All displayed a high-level meropenem resistance (MIC ≥ 8 mg/L), and some belonged to high-risk clones, such as ST15 and ST147. Alterations in ompK35 were also observed, but they did not correlate with high-level meropenem resistance. All isolates were susceptible to ceftazidime/avibactam and porin alterations did not affect the MICs of the latter combination. Cefoxitin together with ertapenem/meropenem low inhibition zone diameters (equal or lower than 16 mm) could strongly suggest alterations affecting OmpK36 in OXA-48-producing K. pneumoniae. OXA-48-producing K. pneumoniae with porin disruptions are a cause of concern; ceftazidime/avibactam showed good in vitro activity against them, so this combination could be positioned as the choice therapy to combat the infections caused by this difficult-to-treat isolates.


2020 ◽  
Vol 64 (12) ◽  
Author(s):  
Ana M. Rada ◽  
Elsa De La Cadena ◽  
Carlos Agudelo ◽  
Cesar Capataz ◽  
Nataly Orozco ◽  
...  

ABSTRACT Carbapenem-resistant Enterobacterales (CRE) pose a significant threat to global public health. The most important mechanism for carbapenem resistance is the production of carbapenemases. Klebsiella pneumoniae carbapenemase (KPC) represents one of the main carbapenemases worldwide. Complex mechanisms of blaKPC dissemination have been reported in Colombia, a country with a high endemicity of carbapenem resistance. Here, we characterized the dynamics of dissemination of blaKPC gene among CRE infecting and colonizing patients in three hospitals localized in a highly endemic area of Colombia (2013 and 2015). We identified the genomic characteristics of KPC-producing Enterobacterales recovered from patients infected/colonized and reconstructed the dynamics of dissemination of blaKPC-2 using both short and long read sequencing. We found that spread of blaKPC-2 among Enterobacterales in the participating hospitals was due to intra- and interspecies horizontal gene transfer (HGT) mediated by promiscuous plasmids associated with transposable elements that was originated from a multispecies outbreak of KPC-producing Enterobacterales in a neonatal intensive care unit. The plasmids were detected in isolates recovered in other units within the same hospital and nearby hospitals. The gene “epidemic” was driven by IncN-pST15-type plasmids carrying a novel Tn4401b structure and non-Tn4401 elements (NTEKPC) in Klebsiella spp., Escherichia coli, Enterobacter spp., and Citrobacter spp. Of note, mcr-9 was found to coexist with blaKPC-2 in species of the Enterobacter cloacae complex. Our findings suggest that the main mechanism for dissemination of blaKPC-2 is HGT mediated by highly transferable plasmids among species of Enterobacterales in infected/colonized patients, presenting a major challenge for public health interventions in developing countries such as Colombia.


mSphere ◽  
2020 ◽  
Vol 5 (5) ◽  
Author(s):  
Willames M. B. S. Martins ◽  
Marisa F. Nicolas ◽  
Yang Yu ◽  
Mei Li ◽  
Priscila Dantas ◽  
...  

ABSTRACT This study provides the genomic characterization and clinical description of bloodstream infections (BSI) cases due to ST15 KPC-2 producer Klebsiella pneumoniae. Six KPC-K. pneumoniae isolates were recovered in 2015 in a tertiary Brazilian hospital and were analyzed by whole-genome sequencing (WGS) (Illumina MiSeq short reads). Of these, two isolates were further analyzed by Nanopore MinION sequencing, allowing complete chromosome and plasmid circularization (hybrid assembly), using Unicycler software. The clinical analysis showed that the 30-day overall mortality for these BSI cases was high (83%). The isolates exhibited meropenem resistance (MICs, 32 to 128 mg/liter), with 3/6 isolates resistant to polymyxin B. The conjugative properties of the blaKPC-2 plasmid and its copy number were assessed by standard conjugation experiments and sequence copy number analysis. We identified in all six isolates a small (8.3-kb), high-copy-number (20 copies/cell) non-self-conjugative IncQ plasmid harboring blaKPC-2 in a non-Tn4401 transposon. This plasmid backbone was previously reported to harbor blaKPC-2 only in Brazil, and it could be comobilized at a high frequency (10−4) into Escherichia coli J53 and into several high-risk K. pneumoniae clones (ST258, ST15, and ST101) by a common IncL/M helper plasmid, suggesting the potential of international spread. This study thus identified the international K. pneumoniae ST15 clone as a carrier of blaKPC-2 in a high-copy-number IncQ1 plasmid that is easily transmissible among other common Klebsiella strains. This finding is of concern since IncQ1 plasmids are efficient antimicrobial resistance determinant carriers across Gram-negative species. The spread of such carbapenemase-encoding IncQ1 plasmids should therefore be closely monitored. IMPORTANCE In many parts of the world, carbapenem resistance is a serious public health concern. In Brazil, carbapenem resistance in Enterobacterales is mostly driven by the dissemination of KPC-2-producing K. pneumoniae clones. Despite being endemic in this country, only a few reports providing both clinical and genomic data are available in Brazil, which limit the understanding of the real clinical impact caused by the dissemination of different clones carrying blaKPC-2 in Brazilian hospitals. Although several of these KPC-2-producer K. pneumoniae isolates belong to the clonal complex 258 and carry Tn4401 transposons located on large plasmids, a concomitant emergence and silent dissemination of small high-copy-number blaKPC-2 plasmids are of importance, as described in this study. Our data identify a small high-copy-number IncQ1 KPC plasmid, its clinical relevance, and the potential for conjugative transfer into several K. pneumoniae isolates, belonging to different international lineages, such as ST258, ST101, and ST15.


2018 ◽  
Vol 62 (8) ◽  
Author(s):  
M. Thwaites ◽  
D. Hall ◽  
D. Shinabarger ◽  
A. W. Serio ◽  
K. M. Krause ◽  
...  

ABSTRACT The next-generation aminoglycoside plazomicin, in development for infections due to multidrug-resistant (MDR) Enterobacteriaceae, was evaluated alongside comparators for bactericidal activity in minimum bactericidal concentration (MBC) and time-kill (TK) assays against MDR Enterobacteriaceae isolates with characterized aminoglycoside and β-lactam resistance mechanisms. Overall, plazomicin and colistin were the most potent, with plazomicin demonstrating an MBC50/90 of 0.5/4 μg/ml and sustained 3-log10 kill against MDR Escherichia coli, Klebsiella pneumoniae, and Enterobacter spp.


2013 ◽  
Vol 57 (3) ◽  
pp. 1488-1495 ◽  
Author(s):  
Laurence Armand-Lefèvre ◽  
Cécile Angebault ◽  
François Barbier ◽  
Emilie Hamelet ◽  
Gilles Defrance ◽  
...  

ABSTRACTIntestinal flora contains a reservoir of Gram-negative bacilli (GNB) resistant to cephalosporins, which are potentially pathogenic for intensive care unit (ICU) patients; this has led to increasing use of carbapenems. The emergence of carbapenem resistance is a major concern for ICUs. Therefore, in this study, we aimed to assess the intestinal carriage of imipenem-resistant GNB (IR-GNB) in intensive care patients. For 6 months, 523 consecutive ICU patients were screened for rectal IR-GNB colonization upon admission and weekly thereafter. The phenotypes and genotypes of all isolates were determined, and a case control study was performed to identify risk factors for colonization. The IR-GNB colonization rate increased regularly from 5.6% after 1 week to 58.6% after 6 weeks in the ICU. In all, 56 IR-GNB strains were collected from 50 patients: 36Pseudomonas aeruginosastrains, 12Stenotrophomonas maltophiliastrains, 6Enterobacteriaceaestrains, and 2Acinetobacter baumanniistrains. InP. aeruginosa, imipenem resistance was due to chromosomally encoded resistance (32 strains) or carbapenemase production (4 strains). In theEnterobacteriaceaestrains, resistance was due to AmpC cephalosporinase and/or extended-spectrum β-lactamase production with porin loss. Genomic comparison showed that the strains were highly diverse, with 8 exceptions (4 VIM-2 carbapenemase-producingP. aeruginosastrains, 2Klebsiella pneumoniaestrains, and 2S. maltophiliastrains). The main risk factor for IR-GNB colonization was prior imipenem exposure. The odds ratio for colonization was already as high as 5.9 (95% confidence interval [95% CI], 1.5 to 25.7) after 1 to 3 days of exposure and increased to 7.8 (95% CI, 2.4 to 29.8) thereafter. In conclusion, even brief exposure to imipenem is a major risk factor for IR-GNB carriage.


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