Robert A Bonomo

Case Western Reserve University School of Medicine, Cleveland, Ohio, United States

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Publications (382)1602.57 Total impact

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    ABSTRACT: We investigate the evolving molecular epidemiology of metallo-β-lactamase (MBL)-producing Pseudomonas aeruginosa isolates collected in a 100 institution, nationwide surveillance study in Japan from 2004 to 2006. MBL-producers were detected in 23/996 isolates (2.3%) in 2004 and 21/992 (2.1%) in 2006. Antimicrobial resistance (specifically, carbapenem resistance) rates between two periods did not differ significantly. MBL-producers were more prevalent in urinary tract isolates. bla IMP-1 group was the most predominant (38 isolates, 80%), followed by 3 bla IMP-7, 2 bla IMP-11 group, and 1 bla VIM-1. All MBL genes were identified in 16 different class 1 integrons, most of which were novel to INTEGRALL database. A total of 17 isolates of sequence type (ST) 235, a recognized worldwide drug-resistant lineage, were distributed in 5 geographic regions across Japan. ST235 isolates included a sublineage associated with In113-like integron. ST357 was identified in 14 isolates, 9 of which harboring a sole bla IMP-1 gene cassette (In994) were recovered from Chugoku region in 2004. ST357 isolates with bla IMP-11 group or ST235 with bla IMP-7 emerged in 2006. We also report for the first time the presence of novel fosI gene cassette in strains other than Mycobacterium spp. Our data give an important "snapshot" of the molecular characteristics and dynamics of MBL-producing lineages in P. aeruginosa in Japan. The significant association of specific genotypes and integrons implies that dissemination and transmission of the preexisting resistant lineage, rather than horizontal gene transfer in situ, might largely explain their endemicity.
    BMC Microbiology 12/2015; 15(1). DOI:10.1186/s12866-015-0378-8 · 2.73 Impact Factor
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    ABSTRACT: Around the world, Burkholderia spp. are emerging as pathogens highly resistant to β-lactam antibiotics, especially ceftazidime. Clinical variants of Burkholderia pseudomallei possessing the class A β-lactamase, PenI with substitutions at positions C69 and P167 are known to demonstrate ceftazidime resistance. However, the biochemical basis for ceftazidime resistance in class A β-lactamases in B. pseudomallei is largely undefined. Here, we performed site-saturation mutagenesis of the C69 position and investigated the kinetic properties of the C69F variant of PenI from B. pseudomallei that results in a high level of ceftazidime resistance (2 → 64 mg/L) when expressed in Escherichia coli . Surprisingly, quantitative immunoblotting shows that steady-state protein levels of the C69F variant are ∼4-fold lower than wild-type PenI (0.76 fg of protein/cell vs. 4.1 fg of protein/cell, respectively). However, growth in the presence of ceftazidime increases the relative amount of the C69F variant to greater than wild-type PenI levels. The C69F variant exhibits a branched kinetic mechanism for ceftazidime hydrolysis thus suggesting there are two different conformations of the enzyme. When incubated with an anti-PenI antibody, one conformation of the C69F variant rapidly hydrolyzes ceftazidime, and most likely contributes to the higher levels of ceftazidime resistance observed in cell-based assays. Molecular dynamics simulations suggest that the electrostatic characteristics of the oxyanion hole are altered in the C69F variant. We advance that when ceftazidime is positioned into the active site, the C69F variant is predicted to form an increased number of hydrogen-bonding interactions than PenI with ceftazidime. In conclusion, we propose “a new twist” for enhanced ceftazidime resistance mediated by the C69F variant of the PenI β-lactamase based on conformational changes in the C69F variant. Our findings explain the biochemical basis of ceftazidime resistance in B . pseudomallei , a pathogen of considerable importance, and suggests that the full repertoire of conformational states of a β-lactamase profoundly effects β-lactam resistance.
    Antimicrobial Agents and Chemotherapy 11/2015; DOI:10.1128/AAC.02073-15 · 4.48 Impact Factor
  • Marisa L Winkler · Robert A Bonomo ·
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    ABSTRACT: Enzymes are continually evolving in response to environmental pressures. In order to increase enzyme fitness, amino acid substitutions can occur leading to a changing function or an increased stability. These evolutionary drivers determine the activity of an enzyme and its success in future generations in response to changing conditions such as environmental stressors or to improve physiological function allowing continual persistence of the enzyme. With recent warning reports on antibiotic resistance and multi-drug resistant bacterial infections, understanding the evolution of β-lactamase enzymes, which are a large contributor to antibiotic resistance, is increasingly important. Here, we investigated a variant of the SHV β-lactamase identified from a clinical isolate of Escherichia coli in 2011 (SHV-129, G238S-E240K-R275L-N276D) to identify the first instance of a global suppressor substitution in the SHV β-lactamase family. We have used this enzyme to show that several evolutionary principles are conserved in different class A β-lactamases, such as active site mutations reducing stability and requiring compensating suppressor substitutions in order to ensure evolutionary persistence of a given β-lactamase. However, the pathway taken by a given β-lactamase in order to reach its evolutionary peak under a given set of conditions is likely different. We also provide further evidence for a conserved stabilizing substitution among class A β-lactamases, the back to consensus M182T substitution. In addition to expanding the spectrum of β-lactamase activity to include the hydrolysis of cefepime, the amino acid substitutions found in SHV-129 provide the enzyme with an excess of stability, which expands the evolutionary landscape of this enzyme and may result in further evolution to potentially include resistance to carbapenems or β-lactamase inhibitors.
    Molecular Biology and Evolution 11/2015; DOI:10.1093/molbev/msv235 · 9.11 Impact Factor
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    IDWeek 2015; 10/2015
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    ABSTRACT: Background: Multi-Drug resistant (MDR) Gram-negative bacilli (GNB) are a growing concern in children. Our long term goals are to describe the impact and define the clinical and molecular epidemiology of this emerging pediatric health threat. Here, we report our molecular findings of ESBL and carbapenemase -containing genotypes in Enterobacteriaceae from children in Chicago. Methods: We conducted a retrospective cohort study of GNB isolates phenotypically identified ESBL or carbapenemase producers, which were recovered from children ages 0-18 years hospitalized between 2011 - 2014 at three Chicago hospitals. We used DNA microarray (Check-Points™) to detect ESBL, plasmid-mediated AmpC (pAmpC) and carbapenemase type beta-lactamase (bla) genes. PCR was performed to assess for plasmid-mediated fluoroquinolone resistance (PMFQR). Repetitive-sequence-based PCR (rep-PCR) and multilocus sequence typing (MLST) were performed to assess isolate similarity. Plasmid replicon typing was conducted to classify plasmids. Results: The median age was 4.3 years, 55% were female, and 44% were outpatients. Most isolates (68%) were from urine. One hundred ninety-three (of 197) isolates exhibiting ESBL –producing or carbapenemase-producing phenotypes were analyzed genotypically; 207 bla genes were detected. The most common species was E. coli (61%), the most frequent genotype was blaCTX-M-1 (49%); 2.6% were CRE (3 carried blaKPC and 1 carried blaIMP) and PMFQR was found in 52/84 (62%) isolates. Overall, pAmpC (blaACT/MIR and blaCMY) were found in 14.2% (28/197) of all isolates and in 77% (17/22) of Enterobacter spp. The predominant E. coli phylogenetic group was B2 (66%) associated with ST43 (ST131) containing blaCTX-M-1 group (67%), and plasmid replicon types F1A, F11, F1B. The blaKPC harboring K. pneumoniae were non ST258 with replicon I1, A/C. Enterobacter carrying blaACT-MIR contained replicon F11A. Conclusion: ESBL and carbapenemase producing Enterobacteriaceae in children are diverse in origin. Like in adults, the predominant strains responsible for ESBL phenotypes are B2-ST43 clonal groups in E. coli containing blaCTX-M-1 group (containing blaCTX-M-15). In contrast, CRE were rare, and blaKPC bearing K. pneumoniae isolates were non ST258, the predominant strain identified in adults. The finding of an IMP gene suggests introduction of metallo-b-lactamases into our population. Plasmid-mediated AmpC may account for a larger percentage of transferable resistance than previously recognized.
    IDweek 2015, San Diego, CA; 10/2015
  • Maria F Mojica · Robert A Bonomo · Walter Fast ·
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    ABSTRACT: Metallo-beta-Lactamases (MBLs) are class B β-lactamases that hydrolyze almost all clinically-available β-lactam antibiotics. MBLs feature the distinctive αβ/βα sandwich fold of the metallo-hydrolase / oxidoreductase superfamily and possess a shallow active-site groove containing one or two divalent zinc ions, flanked by flexible loops. According to sequence identity and zinc ion dependence, MBLs are classified into three subclasses (B1, B2 and B3), of which the B1 subclass enzymes have emerged as the most clinically significant. Differences among the active site architectures, the nature of zinc ligands, and the catalytic mechanisms have limited the development of a common inhibitor. In this review, we will describe the molecular epidemiology and structural studies of the most prominent representatives of class B1 MBLs (NDM-1, IMP-1 and VIM-2) and describe the implications for inhibitor design to counter this growing clinical threat.
    Current drug targets 10/2015; 16(999). DOI:10.2174/1389450116666151001105622 · 3.02 Impact Factor
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    ABSTRACT: CTX-M β-lactamases are one of the fastest growing extended-spectrum β-lactamase (ESBL) families found in Escherichia coli rendering this organism extremely difficult to treat with β-lactam antibiotics . Although they are grouped in class A β-lactamases, the CTX-M family possesses low sequence identity with other enzymes. In addition, they have high hydrolytic activity against oxyimino-cephalosporins, despite having smaller active sites compared to other ESBLs in class A. Similar to most class A enzymes, most of the CTX-M β-lactamases can be inhibited by the clinical inhibitors (clavulanic acid, sulbactam, and tazobactam), but the prevalence of inhibitor resistance is an emerging clinical threat. Thus, the mechanistic details of inhibition pathways are needed for new inhibitor development. Here, we use Raman microscopy to study the CTX-M-9 inactivation reaction with the three commercially available inhibitors and compare these findings to the analysis of the S130G variant. Characterization of the reactions in CTX-M-9 single crystals and solution show the formation of a unique cross-linked species, probably involving Ser70 and Ser130, with subsequent hydrolysis leading to an acrylate species linked to Ser130. In solution, a major population of this species is seen at 25 milliseconds after mixing. Support for this finding comes from the CTX-M-9 S130G variant that reacts with clavulanic acid, sulbactam, and tazobactam in solution, but lacks the characteristic spectroscopic signature for the Ser130-linked species. Understanding the mechanism of inactivation of this clinically important ESBL-type class A lactamase permits us to approach the challenge of inhibitor resistance using knowledge of the bridging species in the inactivation pathway.
    Journal of the American Chemical Society 09/2015; 137(40). DOI:10.1021/jacs.5b10007 · 12.11 Impact Factor
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    ABSTRACT: Background: Rapid molecular diagnostic (RMD) platforms may lead to better antimicrobial stewardship. Our objective was to develop an analytic strategy to enhance the interpretation of RMDs for the clinician. Methods: We compared the performance characteristics of four RMD platforms for detecting resistance against β-lactams in 72 highly drug-resistant isolates of Escherichia coli and Klebsiella pneumoniae (PRIMERS I). Subsequently, two platforms were utilized in a blinded study examining a collection of 196 isolates of E. coli and K. pneumoniae (PRIMERS II). We evaluated the genotypic results as predictors of resistance or susceptibility against a panel of common β-lactam antibiotics. Analytical strategies were designed to include graphical representations of platform performance: i) discrimination summary plots; and ii) determination of susceptibility and resistance predictive values that can be readily interpreted by skilled practitioners to help inform decision making. Results: In PRIMERS I, the four RMD platforms detected β-lactamase (bla) genes and identified susceptibility or resistance in>95% of cases. In PRIMERS II, using a more heterogeneous selection of isolates, the two platforms tested identified susceptibility against extended-spectrum cephalosporins and carbapenems in>90% of cases; but against piperacillin/tazobactam susceptibility was identified in<80% of cases. Applying the statistical tools developed to a population with 15% prevalence of resistance to ceftazidime and 5% resistance to imipenem, RMD platforms predicted susceptibility in>95% of cases; while predicting resistance was lower (69-73% for ceftazidime and 41-50% for imipenem). Conclusions: RMD platforms can assist with informing empiric β-lactam therapy especially in cases where bla genes are not detected (i.e., carbapenemases, etc.) and when the prevalence of resistance is known. Our analysis is a first step in bridging the gap between the clinical microbiology laboratory and empiric treatment decisions using RMDs.
    Clinical Infectious Diseases 09/2015; DOI:10.1093/cid/civ837 · 8.89 Impact Factor
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    ABSTRACT: BACKGROUND The pandemic of carbapenem-resistant Enterobacteriaceae (CRE) was primarily due to clonal spread of bla KPC producing Klebsiella pneumoniae. Thus, thoroughly studied CRE cohorts have consisted mostly of K. pneumoniae. OBJECTIVE To conduct an extensive epidemiologic analysis of carbapenem-resistant Enterobacter spp. (CREn) from 2 endemic and geographically distinct centers. METHODS CREn were investigated at an Israeli center (Assaf Harofeh Medical Center, January 2007 to July 2012) and at a US center (Detroit Medical Center, September 2008 to September 2009). bla KPC genes were queried by polymerase chain reaction. Repetitive extragenic palindromic polymerase chain reaction and pulsed-field gel electrophoresis were used to determine genetic relatedness. RESULTS In this analysis, 68 unique patients with CREn were enrolled. Sixteen isolates (24%) were from wounds, and 33 (48%) represented colonization only. All isolates exhibited a positive Modified Hodge Test, but only 93% (27 of 29) contained bla KPC. Forty-three isolates (63%) were from elderly adults, and 5 (7.4%) were from neonates. Twenty-seven patients died in hospital (40.3% of infected patients). Enterobacter strains consisted of 4 separate clones from Assaf Harofeh Medical Center and of 4 distinct clones from Detroit Medical Center. CONCLUSIONS In this study conducted at 2 distinct CRE endemic regions, there were unique epidemiologic features to CREn: (i) polyclonality, (ii) neonates accounting for more than 7% of cohort, and (iii) high rate of colonization (almost one-half of all cases represented colonization). Since false-positive Modified Hodge Tests in Enterobacter spp. are common, close monitoring of carbapenem resistance mechanisms (particularly carbapenemase production) among Enterobacter spp. is important. Infect. Control Hosp. Epidemiol. 2015;00(0):1-9.
    Infection Control and Hospital Epidemiology 09/2015; DOI:10.1017/ice.2015.186 · 4.18 Impact Factor
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    ABSTRACT: Cefepime is frequently prescribed to treat infections caused by AmpC-producing Gram-negative bacteria. CMY-2 is the most common plasmid-mediated AmpC (pAmpC) β-lactamase. Unfortunately, CMY variants conferring enhanced cefepime resistance are reported. Here, we describe the evolution of CMY-2 to an extended-spectrum AmpC (ESAC) in clonally identical E. coli isolates obtained from a patient. The CMY-2-producing E. coli (CMY-2- Ec ) was isolated from a wound. Thirty days later, one CMY-33-producing E. coli (CMY-33- Ec ) was detected in bronchoalveolar lavage. Two weeks before the isolation of CMY-33- Ec , the patient received cefepime. CMY-33- Ec and CMY-2- Ec were identical by rep-PCR, being of hyperepidemic ST131, but showed different β-lactam MICs (e.g., cefepime 16 vs . ≤0.5 μg/ml). Identical CMY-2- Ec isolates were also found in a rectal swab. CMY-33 differs from CMY-2 by a Leu293-Ala294 deletion. Expressed in E. coli DH10B, both CMYs conferred resistance to ceftazidime (≥256 μg/ml), but cefepime MICs were higher for CMY-33 than CMY-2 (8 vs . 0.25 μg/ml). The k cat / K m or k inact / K I (μM -1 s -1 ) indicated that CMY-33 possesses an ESBL-like spectrum compared to CMY-2 (cefoxitin: 0.2 vs . 0.4; ceftazidime: 0.2 vs . not measurable; cefepime: 0.2 vs . not measurable; tazobactam 0.0018 vs . 0.0009). Using molecular modeling, we show that a widened active site (∼4 Å shift) may play a significant role in enhancing cefepime hydrolysis. This is the first in vivo demonstration of a pAmpC that under cephalosporin treatment expands its substrate spectrum resembling an ESBL. The prevalence of CMY-2- Ec isolates is rapidly increasing worldwide, therefore awareness that cefepime treatment may select for resistant isolates is critical.
    Antimicrobial Agents and Chemotherapy 09/2015; 59(12):AAC.01804-15. DOI:10.1128/AAC.01804-15 · 4.48 Impact Factor
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    ABSTRACT: Background: Infections due to multi-drug resistant (MDR) Gram-negative bacilli (GNB) are a growing problem in children. Our long term goals are to investigate the impact of MDR GNB infections and to define the molecular epidemiology of this emerging health threat. Here, we report our findings concerning PMFQR in children. Methods: A retrospective cohort study of clinical GNB isolates obtained from children ages 0-21 years hospitalized between 2011-14 at three Chicago hospitals was performed. To assess for PMFQR, PCR was used. Repetitive-sequence-based PCR (rep-PCR) was used to determine genetic similarity. PCR and DNA microarray (Check-Points CT101) were used to assess for beta-lactamase genes (bla). Multilocus sequence typing (MLST), PCR and DNA sequencing were performed on representative isolates for bacterial nomenclature and characterization. Results: Of 169 ESBL-producing Enterobacteriaceae isolates with antibiogram data, 85(50.3%) were FQR of which 82 were available for testing. The median age of patients was 4.8 years. The predominant FQR organism was E. coli 65/82 (79%) and predominant bla genotype associated with FQR in Enterobacteriaceae was blaCTX-M-1 group in 51/82 cases (62%). Within ESBL E. coli, FQR was commonly associated with phylogenetic group B2 and/or ST43 (ST131 in Achtman’s MLST scheme) containing blaCTX-M-1 group in 47/63 cases (75%). PMFQR was found in 56/82 (68.3%), of which the aac 6’1b-cr (Y102R and/or D179Y) gene mutation was most common (56%). PMFQR genes oqxA, oqxB, qepA and qnrb were found in 10%, 7%, 9% and 4%, respectively. Several isolates contained >1 bla/PMFQR gene. Conclusions: We define the molecular epidemiology of PMFQR in ESBL-producing Enterobacteriaceae in children. The majority of FQR ESBLs in children are linked with PMFQR mechanisms. The predominant strains responsible are B2-ST43 clonal groups of ESBL-producing E. coli containing blaCTX-M-1 group (containing blaCTX-M-15); however, PMFQR in these organisms is associated with multiple bla types.
    ICAAC-ICC 2015, San Diego, CA; 09/2015
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    ABSTRACT: Antibiotic resistance in bacteria is ever changing and adapting, as once novel β-lactam antibiotics are losing their efficacy primarily due to the production of β-lactamases. Metallo-β-lactamases (MBLs) efficiently inactivate a broad range of β-lactam antibiotics including carbapenems and are often co-expressed with other antibacterial resistance factors. The rapid dissemination of MBLs and lack of novel antibacterials pose an imminent threat to global health. In an effort to better counter these resistance-conferring β-lactamases, an investigation of their natural evolution and resulting substrate specificity is employed. In this study, we elucidate the effect of different amino acid substitutions at position 67 in IMP-type MBLs on their ability to hydrolyze and confer resistance to a range of β-lactam antibiotics. Wild-type β-lactamases IMP-1 and IMP-10 and mutants IMP-1-V67A and IMP-1-V67I were biophysically and biochemically characterized and minimum inhibitory concentrations (MICs) for Escherichia coli cells expressing these enzymes were determined. We found that all variants exhibited catalytic efficiencies (kcat/Km) equal to or higher than IMP-1 against all tested β-lactams except penicillins, against which IMP-1 and IMP-1-V67I showed highest kcat/Km. The substrate-specific effects of the different amino acid substitutions at position 67 are discussed in light of their side-chain structures and possible interactions with the substrates. Docking calculations were employed to investigate interactions between different side chains and an inhibitor as a β-lactam surrogate. The differences in binding affinities determined experimentally and computationally seem to be governed by hydrophobic interactions between residue 67 and the inhibitor, and by inference, the β-lactam substrates.
    Antimicrobial Agents and Chemotherapy 09/2015; 59(12). DOI:10.1128/AAC.01651-15 · 4.48 Impact Factor
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    ABSTRACT: The increasing rate of antibiotic resistance and slowing discovery of novel antibiotic treatments presents a growing threat to public health. Here, we consider a simple model of evolution in asexually reproducing populations which considers adaptation as a biased random walk on a fitness landscape. This model associates the global properties of the fitness landscape with the algebraic properties of a Markov chain transition matrix and allows us to derive general results on the non-commutativity and irreversibility of natural selection as well as antibiotic cycling strategies. Using this formalism, we analyze 15 empirical fitness landscapes of E. coli under selection by different β-lactam antibiotics and demonstrate that the emergence of resistance to a given antibiotic can be either hindered or promoted by different sequences of drug application. Specifically, we demonstrate that the majority, approximately 70%, of sequential drug treatments with 2-4 drugs promote resistance to the final antibiotic. Further, we derive optimal drug application sequences with which we can probabilistically 'steer' the population through genotype space to avoid the emergence of resistance. This suggests a new strategy in the war against antibiotic-resistant organisms: drug sequencing to shepherd evolution through genotype space to states from which resistance cannot emerge and by which to maximize the chance of successful therapy.
    PLoS Computational Biology 09/2015; 11(9):e1004493. DOI:10.1371/journal.pcbi.1004493 · 4.62 Impact Factor
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    ABSTRACT: β-Lactamase inhibition is an important clinical strategy in overcoming β-lactamase-mediated resistance to β-lactam antibiotics in Gram negative bacteria. A new β-lactamase inhibitor, avibactam, is entering the clinical arena and promising to be a major step forward in our antibiotic armamentarium. Avibactam has remarkable broad-spectrum activity in being able to inhibit classes A, C, and some class D β-lactamases. We present here structural investigations into class A β-lactamase inhibition by avibactam as we report the crystal structures of SHV-1, the chromosomal penicillinase of Klebsiella pneumoniae, and KPC-2, an acquired carbapenemase found in the same pathogen, complexed with avibactam. The 1.80 Å KPC-2 and 1.42 Å resolution SHV-1 β-lactamase avibactam complex structures reveal avibactam covalently bonded to the catalytic S70 residue. Analysis of the interactions and chair-shaped conformation of avibactam bound to the active sites of KPC-2 and SHV-1 provides structural insights into recently laboratory-generated amino acid substitutions that result in resistance to avibactam in KPC-2 and SHV-1. Furthermore, we observed several important differences in the interactions with amino acid residues, in particular that avibactam forms hydrogen bonds to S130 in KPC-2 but not in SHV-1, that can possibly explain some of the different kinetic constants of inhibition. Our observations provide a possible reason for the ability of KPC-2 β-lactamase to slowly desulfate avibactam with a potential role for the stereochemistry around the N1 atom of avibactam and/or the presence of an active site water molecule that could aid in avibactam desulfation, an unexpected consequence of novel inhibition chemistry.
    PLoS ONE 09/2015; 10(9):e0136813. DOI:10.1371/journal.pone.0136813 · 3.23 Impact Factor
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    ABSTRACT: Staphylococcus intermedius and Staphylococcus pseudintermedius are difficult to distinguish using conventional microbiological methods. Molecular diagnostic tools change our understanding of the epidemiology of these 2 organisms. In this study, we present (1) a detailed review of the current literature on molecular diagnostics and (2) a case series in which misidentification was proven in 1 case. We conclude that S pseudintermedius is a more common human pathogen than previously recognized.
    09/2015; 2(3):ofv110. DOI:10.1093/ofid/ofv110
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    ABSTRACT: This study compared the performance of the Carba NP assay published by the Clinical Laboratory Standards Institute and the Rosco Rapid CARB screen kit. Carba NP had superior sensitivity but both assays required an increased inoculum to detect carbapenemase production in isolates with blaNDM, blaIMP, and blaOXA-48. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
    Journal of clinical microbiology 08/2015; 53(10). DOI:10.1128/JCM.01547-15 · 3.99 Impact Factor
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    ABSTRACT: Mycobacterium tuberculosis is intrinsically resistant to most -lactam antibiotics due to the constitutive expression of the blaC-encoded -lactamase. This enzyme has extremely high activity against penicillins and cephalosporins, but weaker activity against carbapenems. The enzyme can be inhibited by clavulanate, avibactam and boronic acids. In the present study, we investigated the ability of 6-methylidene -lactams to inhibit BlaC. One such compound, Penem 2, inhibited BlaC more than 70 times more efficiently than clavulanate. The compound forms a covalent complex with BlaC as shown by mass spectrometry. Crystallization of the complex revealed that the bound inhibitor was covalently attached via the Ser70 active site residue and that the covalently, acylated form of the inhibitor had undergone additional chemistry yielding a 4,7-thiazepine ring in place of the -lactam and thiazapyroline ring generated as a result of -lactam ring opening. The stereochemistry of the product of the 7-endo-trig cyclization was opposite to that observed previously for Class A and D -lactamases. Addition of Penem 2 greatly synergized the antibacterial properties of both ampicillin and meropenem against growing culture of M. tuberculosis. Strikingly, Penem 2 alone showed significant growth inhibition, suggesting that in addition to its capability of efficiently inhibiting BlaC, that it also inhibited the peptidoglycan cross-linking transpeptidases.
    Biochemistry 08/2015; 54(36). DOI:10.1021/acs.biochem.5b00698 · 3.02 Impact Factor
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    ABSTRACT: Carbapenem-resistant Enterobacteriaceae (CRE) usually infect patients with significant comorbidities and health care exposures. We present a case of a pregnant woman who developed community-acquired pyelonephritis caused by KPC-producing Klebsiella pneumoniae. Despite antibiotic treatment, she experienced spontaneous prolonged rupture of membranes, with eventual delivery of a healthy infant. This report demonstrates the challenge that CRE may pose to the effective treatment of common infections in obstetric patients, with potentially harmful consequences to maternal and neonatal health.
    Antimicrobial Agents and Chemotherapy 08/2015; 59(8-8):4375-8. DOI:10.1128/aac.00553-15 · 4.48 Impact Factor
  • Andrea Endimiani · Robert Bonomo ·

    07/2015; 03(04):217-220. DOI:10.1055/s-0035-1557003
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    ABSTRACT: Pathogenic Gram-negative bacteria resistant to almost all β-lactam antibiotics are a major public health threat. Zn(II)-dependent or metallo-β-lactamases (MBLs) produced by these bacteria inactivate most β-lactam antibiotics, including the carbapenems, which are “last line therapies” for life-threatening Gram-negative infections. NDM-1 is a carbapenemase belonging to the MBL family that is rapidly spreading worldwide. Regrettably, inhibitors of MBLs are not yet developed. Here we present the bisthiazolidine (BTZ) scaffold as a structure with some features of β-lactam substrates, which can be modified with metal-binding groups to target the MBL active site. Inspired by known interactions of MBLs with β-lactams, we designed four BTZs that behave as in vitro NDM-1 inhibitors with Ki values in the low micromolar range (from 7 ± 1 to 19 ± 3 μM). NMR spectroscopy demonstrated that they inhibit hydrolysis of imipenem in NDM-1-producing Escherichia coli. In vitro time kill cell-based assays against a variety of bacterial strains harboring blaNDM-1 including Acinetobacter baumannii show that the compounds restore the antibacterial activity of imipenem. A crystal structure of the most potent heterocycle (L-CS319) in complex with NDM-1 at 1.9 Å resolution identified both structural determinants for inhibitor binding and opportunities for further improvements in potency.
    07/2015; DOI:10.1021/acsinfecdis.5b00046

Publication Stats

11k Citations
1,602.57 Total Impact Points


  • 2002-2015
    • Case Western Reserve University School of Medicine
      • • Department of Molecular Biology and Microbiology
      • • Department of Medicine
      Cleveland, Ohio, United States
  • 1996-2015
    • Louis Stokes Cleveland VA Medical Center
      Cleveland, Ohio, United States
  • 1992-2015
    • Case Western Reserve University
      • • Department of Molecular Biology and Microbiology
      • • School of Medicine
      • • Department of Pharmacology
      • • Department of Biochemistry
      • • Division of Infectious Diseases and HIV Medicine
      Cleveland, Ohio, United States
  • 2014
    • University of North Carolina at Chapel Hill
      North Carolina, United States
    • United States Department of Veterans Affairs
      Bedford, Massachusetts, United States
  • 2008-2014
    • San Francisco VA Medical Center
      San Francisco, California, United States
  • 2013
    • Northeast Ohio Medical University
      • Department of Internal Medicine
      Ravenna, Ohio, United States
  • 2010-2012
    • Southern Methodist University
      • Department of Chemistry
      Dallas, Texas, United States
  • 1997-2012
    • Cleveland State University
      • Department of Chemistry
      Cleveland, Ohio, United States
  • 2011
    • Detroit Medical Center
      Detroit, Michigan, United States
    • Centre Hospitalier Universitaire de Clermont-Ferrand
      Clermont, Auvergne, France
  • 2009-2011
    • Mount Sinai School of Medicine
      • Department of Medicine
      Manhattan, NY, United States
    • Saint Edward's University
      Austin, Texas, United States
  • 2008-2010
    • U.S. Department of Veterans Affairs
      Washington, Washington, D.C., United States
  • 2007
    • Emory University
      • Department of Microbiology and Immunology
      Atlanta, Georgia, United States
  • 2006
    • University of Helsinki
      Helsinki, Uusimaa, Finland
  • 2005
    • Semmelweis University
      Budapeŝto, Budapest, Hungary
  • 2003-2005
    • University of Pittsburgh
      • Division of Infectious Diseases
      Pittsburgh, PA, United States
  • 1998-2005
    • University of Connecticut
      • Department of Molecular and Cell Biology
      Сторс, Connecticut, United States
  • 2004
    • Minneapolis Veterans Affairs Hospital
      Minneapolis, Minnesota, United States