scholarly journals 995. A Murine Model of Klebsiella pneumoniae Gastrointestinal Colonization with Parenteral Vancomycin Administration

2021 ◽  
Vol 8 (Supplement_1) ◽  
pp. S588-S588
Author(s):  
Bettina Cheung ◽  
Marine Lebrun-Corbin ◽  
Alan R Hauser
Keyword(s):  
Klebsiella Pneumoniae ◽  
Mouse Model ◽  
The United States ◽  
Post Inoculation ◽  
Fecal Shedding ◽  
Carbapenem Resistant ◽  
Human Dose ◽  
Colony Forming Units ◽  
Multiple Strains ◽  
Gastrointestinal Colonization

Abstract Background As a leading cause of nosocomial infections, Klebsiella pneumoniae poses a significant threat due to its propensity to acquire resistance to many classes of antibiotics, including carbapenems. Gastrointestinal (GI) colonization by K. pneumoniae is a risk factor for subsequent infection as well as transmission to other patients. To study this crucial step in pathogenesis, we developed a mouse model of K. pneumoniae GI colonization using a clinically relevant parenteral antibiotic regimen. Methods To improve the clinical relevance of our model, we elected to use intraperitoneal injections of vancomycin, one of the most highly utilized antibiotics in the United States. Results To optimize dosage in C57bl/6 mice, we injected 20mg/kg, 350mg/kg, or vehicle (PBS) for three days prior to gastric gavage with 108 colony forming units (CFU) of a low-resistance strain of K. pneumoniae. The mice who received 350mg/kg (a mouse equivalent of a human dose of 1g/day calculated through the FDA guidelines for estimating safe dosing) shed about 107 CFU/g of feces at Day 7 while those receiving the lower dose or vehicle shed 104 CFU/g. Next, we compared 3- or 5-day pre-treatments with vancomycin prior to inoculation with an ST258 (epidemic carbapenem-resistant) strain. At Day 7 post-inoculation, mice who received 5 days shed 1010 CFU/g feces while those who received vancomycin for 3 days or vehicle for 5 days (PBS) shed 106 or 104 CFU/g feces respectively. Thus, we chose 5 days of 350mg/kg vancomycin injection as our regimen for inducing robust GI colonization in mice. Finally, we tested the durability of colonization by following fecal shedding in mice up to Day 60 post-inoculation with a second ST258 strain. Shedding during the first 7 days occurs at about 1010 CFU/g feces, and from day 14 to day 60 fecal loads are stable around 107 CFU/g feces. Results are comparable between male and female mice. Conclusion In conclusion, we have developed a mouse model of robust, prolonged GI colonization with multiple strains of K. pneumoniae using controlled dosing of a clinically relevant antibiotic. This model may be used to study a key step in K. pneumoniae pathogenesis and infection prevention in the future. Disclosures All Authors: No reported disclosures

scholarly journals Colistin Heteroresistance Is Largely Undetected among Carbapenem-Resistant Enterobacterales in the United States

mBio ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Victor I. Band ◽  
Sarah W. Satola ◽  
Richard D. Smith ◽  
David A. Hufnagel ◽  
Chris Bower ◽  
...  
Keyword(s):  
United States ◽  
Klebsiella Pneumoniae ◽  
Diagnostic Testing ◽  
Cladistic Analysis ◽  
The United States ◽  
Clinical Diagnostics ◽  
Infection Model ◽  
Content Type ◽  
Carbapenem Resistant ◽  
Clinical Diagnostic

ABSTRACT Heteroresistance is a form of antibiotic resistance where a bacterial strain is comprised of a minor resistant subpopulation and a majority susceptible subpopulation. We showed previously that colistin heteroresistance can mediate the failure of colistin therapy in an in vivo infection model, even for isolates designated susceptible by clinical diagnostics. We sought to characterize the extent of colistin heteroresistance among the highly drug-resistant carbapenem-resistant Enterobacterales (CRE). We screened 408 isolates for colistin heteroresistance. These isolates were collected between 2012 and 2015 in eight U.S. states as part of active surveillance for CRE. Colistin heteroresistance was detected in 10.1% (41/408) of isolates, and it was more common than conventional homogenous resistance (7.1%, 29/408). Most (93.2%, 38/41) of these heteroresistant isolates were classified as colistin susceptible by standard clinical diagnostic testing. The frequency of colistin heteroresistance was greatest in 2015, the last year of the study. This was especially true among Enterobacter isolates, of which specific species had the highest rates of heteroresistance. Among Klebsiella pneumoniae isolates, which were the majority of isolates tested, there was a closely related cluster of colistin-heteroresistant ST-258 isolates found mostly in Georgia. However, cladistic analysis revealed that, overall, there was significant diversity in the genetic backgrounds of heteroresistant K. pneumoniae isolates. These findings suggest that due to being largely undetected in the clinic, colistin heteroresistance among CRE is underappreciated in the United States. IMPORTANCE Heteroresistance is an underappreciated phenomenon that may be the cause of some unexplained antibiotic treatment failures. Misclassification of heteroresistant isolates as susceptible may lead to inappropriate therapy. Heteroresistance to colistin was more common than conventional resistance and was overwhelmingly misclassified as susceptibility by clinical diagnostic testing. Higher proportions of colistin heteroresistance observed in certain Enterobacter species and clustering among heteroresistant Klebsiella pneumoniae strains may inform colistin treatment recommendations. Overall, the rate of colistin nonsusceptibility was more than double the level detected by clinical diagnostics, suggesting that the prevalence of colistin nonsusceptibility among CRE may be higher than currently appreciated in the United States.

scholarly journals IMP-Producing Carbapenem-Resistant Klebsiella pneumoniae in the United States

2011 ◽  
Vol 49 (12) ◽  
pp. 4239-4245 ◽  
Author(s):  
B. M. Limbago ◽  
J. K. Rasheed ◽  
K. F. Anderson ◽  
W. Zhu ◽  
B. Kitchel ◽  
...  
Keyword(s):  
United States ◽  
Klebsiella Pneumoniae ◽  
The United States ◽  
Carbapenem Resistant

scholarly journals Nacubactam Enhances Meropenem Activity against Carbapenem-Resistant Klebsiella pneumoniae Producing KPC

2019 ◽  
Vol 63 (8) ◽  
Author(s):  
Melissa D. Barnes ◽  
Magdalena A. Taracila ◽  
Caryn E. Good ◽  
Saralee Bajaksouzian ◽  
Laura J. Rojas ◽  
...  
Keyword(s):  
Molecular Modeling ◽  
Klebsiella Pneumoniae ◽  
The United States ◽  
Alternative Mechanism ◽  
Enhancer Activity ◽  
Content Type ◽  
Class A ◽  
Carbapenem Resistant ◽  
Biochemical Analyses ◽  
Molecular Modeling And Docking

ABSTRACT Carbapenem-resistant Enterobacteriaceae (CRE) are resistant to most antibiotics, making CRE infections extremely difficult to treat with available agents. Klebsiella pneumoniae carbapenemases (KPC-2 and KPC-3) are predominant carbapenemases in CRE in the United States. Nacubactam is a bridged diazabicyclooctane (DBO) β-lactamase inhibitor that inactivates class A and C β-lactamases and exhibits intrinsic antibiotic and β-lactam “enhancer” activity against Enterobacteriaceae. In this study, we examined a collection of meropenem-resistant K. pneumoniae isolates carrying blaKPC-2 or blaKPC-3; meropenem-nacubactam restored susceptibility. Upon testing isogenic Escherichia coli strains producing KPC-2 variants with single-residue substitutions at important Ambler class A positions (K73, S130, R164, E166, N170, D179, K234, E276, etc.), the K234R variant increased the meropenem-nacubactam MIC compared to that for the strain producing KPC-2, without increasing the meropenem MIC. Correspondingly, nacubactam inhibited KPC-2 (apparent Ki [Ki app] = 31 ± 3 μM) more efficiently than the K234R variant (Ki app = 270 ± 27 μM) and displayed a faster acylation rate (k2/K), which was 5,815 ± 582 M−1 s−1 for KPC-2 versus 247 ± 25 M−1 s−1 for the K234R variant. Unlike avibactam, timed mass spectrometry revealed an intact sulfate on nacubactam and a novel peak (+337 Da) with the K234R variant. Molecular modeling of the K234R variant showed significant catalytic residue (i.e., S70, K73, and S130) rearrangements that likely interfere with nacubactam binding and acylation. Nacubactam’s aminoethoxy tail formed unproductive interactions with the K234R variant’s active site. Molecular modeling and docking observations were consistent with the results of biochemical analyses. Overall, the meropenem-nacubactam combination is effective against carbapenem-resistant K. pneumoniae. Moreover, our data suggest that β-lactamase inhibition by nacubactam proceeds through an alternative mechanism compared to that for avibactam.

scholarly journals ARGONAUT II Study of the In Vitro Activity of Plazomicin against Carbapenemase-Producing Klebsiella pneumoniae

2020 ◽  
Vol 64 (5) ◽  
Author(s):  
Michael R. Jacobs ◽  
Caryn E. Good ◽  
Andrea M. Hujer ◽  
Ayman M. Abdelhamed ◽  
Daniel D. Rhoads ◽  
...  
Keyword(s):  
United States ◽  
16S Rrna ◽  
Klebsiella Pneumoniae ◽  
Great Lakes ◽  
The United States ◽  
Great Lakes Region ◽  
In Vitro Activity ◽  
Content Type ◽  
Carbapenem Resistant

ABSTRACT Plazomicin was tested against 697 recently acquired carbapenem-resistant Klebsiella pneumoniae isolates from the Great Lakes region of the United States. Plazomicin MIC50 and MIC90 values were 0.25 and 1 mg/liter, respectively; 680 isolates (97.6%) were susceptible (MICs of ≤2 mg/liter), 9 (1.3%) intermediate (MICs of 4 mg/liter), and 8 (1.1%) resistant (MICs of >32 mg/liter). Resistance was associated with rmtF-, rmtB-, or armA-encoded 16S rRNA methyltransferases in all except 1 isolate.

scholarly journals A Prolonged Outbreak of KPC-3-Producing Enterobacter cloacae and Klebsiella pneumoniae Driven by Multiple Mechanisms of Resistance Transmission at a Large Academic Burn Center

2016 ◽  
Vol 61 (2) ◽  
Author(s):  
Hajime Kanamori ◽  
Christian M. Parobek ◽  
Jonathan J. Juliano ◽  
David van Duin ◽  
Bruce A. Cairns ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Molecular Mechanisms ◽  
Enterobacter Cloacae ◽  
The United States ◽  
Multidrug Resistant ◽  
Control Measures ◽  
Content Type ◽  
Burn Center ◽  
Infection Control Measures ◽  
Carbapenem Resistant

ABSTRACT Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacter cloacae has been recently recognized in the United States. Whole-genome sequencing (WGS) has become a useful tool for analysis of outbreaks and for determining transmission networks of multidrug-resistant organisms in health care settings, including carbapenem-resistant Enterobacteriaceae (CRE). We experienced a prolonged outbreak of CRE E. cloacae and K. pneumoniae over a 3-year period at a large academic burn center despite rigorous infection control measures. To understand the molecular mechanisms that sustained this outbreak, we investigated the CRE outbreak isolates by using WGS. Twenty-two clinical isolates of CRE, including E. cloacae (n = 15) and K. pneumoniae (n = 7), were sequenced and analyzed genetically. WGS revealed that this outbreak, which seemed epidemiologically unlinked, was in fact genetically linked over a prolonged period. Multiple mechanisms were found to account for the ongoing outbreak of KPC-3-producing E. cloacae and K. pneumoniae. This outbreak was primarily maintained by a clonal expansion of E. cloacae sequence type 114 (ST114) with distribution of multiple resistance determinants. Plasmid and transposon analyses suggested that the majority of bla KPC-3 was transmitted via an identical Tn4401b element on part of a common plasmid. WGS analysis demonstrated complex transmission dynamics within the burn center at levels of the strain and/or plasmid in association with a transposon, highlighting the versatility of KPC-producing Enterobacteriaceae in their ability to utilize multiple modes to resistance gene propagation.

scholarly journals Outbreak of Klebsiella pneumoniae Producing a New Carbapenem-Hydrolyzing Class A β-Lactamase, KPC-3, in a New York Medical Center

2004 ◽  
Vol 48 (12) ◽  
pp. 4793-4799 ◽  
Author(s):  
Neil Woodford ◽  
Philip M. Tierno ◽  
Katherine Young ◽  
Luke Tysall ◽  
Marie-France I. Palepou ◽  
...  
Keyword(s):  
New York ◽  
Klebsiella Pneumoniae ◽  
Medical Center ◽  
The United States ◽  
Outbreak Strain ◽  
Class A ◽  
Carbapenem Resistant ◽  
Novel Variant ◽  
Resistant Strains

ABSTRACT From April 2000 to April 2001, 24 patients in intensive care units at Tisch Hospital, New York, N.Y., were infected or colonized by carbapenem-resistant Klebsiella pneumoniae. Pulsed-field gel electrophoresis identified a predominant outbreak strain, but other resistant strains were also recovered. Three representatives of the outbreak strain from separate patients were studied in detail. All were resistant or had reduced susceptibility to imipenem, meropenem, ceftazidime, piperacillin-tazobactam, and gentamicin but remained fully susceptible to tetracycline. PCR amplified a bla KPC allele encoding a novel variant, KPC-3, with a His(272)→Tyr substitution not found in KPC-2; other carbapenemase genes were absent. In the outbreak strain, KPC-3 was encoded by a 75-kb plasmid, which was transferred in vitro by electroporation and conjugation. The isolates lacked the OmpK35 porin but expressed OmpK36, implying reduced permeability as a cofactor in resistance. This is the third KPC carbapenem-hydrolyzing β-lactamase variant to have been reported in members of the Enterobacteriaceae, with others reported from the East Coast of the United States. Although producers of these enzymes remain rare, the progress of this enzyme group merits monitoring.

scholarly journals Surveillance of Carbapenem-Resistant Klebsiella pneumoniae: Tracking Molecular Epidemiology and Outcomes through a Regional Network

2014 ◽  
Vol 58 (7) ◽  
pp. 4035-4041 ◽  
Author(s):  
David van Duin ◽  
Federico Perez ◽  
Susan D. Rudin ◽  
Eric Cober ◽  
Jennifer Hanrahan ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Long Term Care ◽  
Carbapenem Resistance ◽  
The United States ◽  
Molecular Characteristics ◽  
Regional Network ◽  
Term Care ◽  
Content Type ◽  
Carbapenem Resistant

ABSTRACTCarbapenem resistance in Gram-negative bacteria is on the rise in the United States. A regional network was established to study microbiological and genetic determinants of clinical outcomes in hospitalized patients with carbapenem-resistant (CR)Klebsiella pneumoniaein a prospective, multicenter, observational study. To this end, predefined clinical characteristics and outcomes were recorded andK. pneumoniaeisolates were analyzed for strain typing and resistance mechanism determination. In a 14-month period, 251 patients were included. While most of the patients were admitted from long-term care settings, 28% of them were admitted from home. Hospitalizations were prolonged and complicated. Nonsusceptibility to colistin and tigecycline occurred in isolates from 7 and 45% of the patients, respectively. Most of the CRK. pneumoniaeisolates belonged to repetitive extragenic palindromic PCR (rep-PCR) types A and B (both sequence type 258) and carried eitherblaKPC-2(48%) orblaKPC-3(51%). One isolate tested positive forblaNDM-1, a sentinel discovery in this region. Important differences between strain types were noted; rep-PCR type B strains were associated withblaKPC-3(odds ratio [OR], 294; 95% confidence interval [CI], 58 to 2,552;P< 0.001), gentamicin nonsusceptibility (OR, 24; 95% CI, 8.39 to 79.38;P< 0.001), amikacin susceptibility (OR, 11.0; 95% CI, 3.21 to 42.42;P< 0.001), tigecycline nonsusceptibility (OR, 5.34; 95% CI, 1.30 to 36.41;P= 0.018), a shorter length of stay (OR, 0.98; 95% CI, 0.95 to 1.00;P= 0.043), and admission from a skilled-nursing facility (OR, 3.09; 95% CI, 1.26 to 8.08;P= 0.013). Our analysis shows that (i) CRK. pneumoniaeis seen primarily in the elderly long-term care population and that (ii) regional monitoring of CRK. pneumoniaereveals insights into molecular characteristics. This work highlights the crucial role of ongoing surveillance of carbapenem resistance determinants.

scholarly journals Multiplex PCR Analysis for Rapid Detection of Klebsiella pneumoniae Carbapenem-Resistant (Sequence Type 258 [ST258] and ST11) and Hypervirulent (ST23, ST65, ST86, and ST375) Strains

2018 ◽  
Vol 56 (9) ◽  
Author(s):  
Fangyou Yu ◽  
Jingnan Lv ◽  
Siqiang Niu ◽  
Hong Du ◽  
Yi-Wei Tang ◽  
...  
Keyword(s):  
United States ◽  
Klebsiella Pneumoniae ◽  
Multiplex Pcr ◽  
Virulence Genes ◽  
The United States ◽  
Sequence Type ◽  
Pcr Assay ◽  
Content Type ◽  
Carbapenem Resistant ◽  
Resistant Strains

ABSTRACT Carbapenem-resistant and hypervirulent Klebsiella pneumoniae strains have emerged recently. These strains are both hypervirulent and multidrug resistant and may also be highly transmissible and able to cause severe infections in both the hospital and the community. Clinical and public health needs require a rapid and comprehensive molecular detection assay to identify and track the spread of these strains and provide timely infection control information. Here, we develop a rapid multiplex PCR assay capable of distinguishing K. pneumoniae carbapenem-resistant isolates of sequence type 258 (ST258) and ST11, and hypervirulent ST23, ST65/ST375, and ST86 clones, as well as capsular types K1, K2, K locus type 47 (KL47), and KL64, and virulence genes rmpA, rmpA2, iutA, and iroN. The assay demonstrated 100% concordance with 118 previously genotyped K. pneumoniae isolates and revealed different populations of carbapenem-resistant and hypervirulent strains in two collections in China and the United States. The results showed that carbapenem-resistant and hypervirulent K. pneumoniae strains are still rare in the United States, whereas in China, ∼50% of carbapenem-resistant strains carry rmpA/rmpA2 and iutA virulence genes, which are largely associated with the epidemic ST11 strains. Similarly, a high prevalence of hypervirulent strains was found in carbapenem-susceptible isolates in two Chinese hospitals, but these primarily belong to ST23, ST65/ST375, and ST86, which are distinct from the carbapenem-resistant strains. Taken together, our results demonstrated that this PCR assay can be a useful tool for molecular surveillance of carbapenem-resistant and hypervirulent K. pneumoniae strains.

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