Central Annals of Clinical and Medical Microbiology Review Article *Corresponding author Metin Doğan, Department of Microbiology, Necmettin Erbakan University, Turkey, Tel: 90 535 307 16 15; Fax: 90 Overview of b-Lactamases 332 2236384; Email: Submitted: 24 September 2018 and Current Techniques for Accepted: 16 November 2018 Published: 17 November 2018 ISSN: 2578-3629 Detecting Beta-Lactamase Copyright © 2018 Doğan et al. Mediated Resistance OPEN ACCESS Selin Uğraklı and Metin Doğan* Keywords • Beta-lactamase; ESBL; Antibiotic resistance; Department of Microbiology, Necmettin Erbakan University, Turkey Carbapenamases Abstract Beta-lactam is a major antibiotic group that carries beta-lactam ring in the structure of antibiotics. Beta-lactam antibiotics are divided into 5 basic classes as penicillins, cephalosporins, monobactams, carbapenems and beta-lactamase inhibitors according to the beta-lactam ring side chains and other rings. All beta-lactam antibiotics affect by inhibiting the enzymes (penicillin binding proteins, PBPs) involved in the cross-linking of the peptidoglycan layer of the cell wall, which is depotentiated, and this leads to osmotic rupture. Beta-lactam antibiotics are one of the most common antibacterial agents used in the treatment of both community and hospital-acquired infections. Due to the widespread use of beta-lactam antibiotics, it is observed that bacteria also develop new resistance mechanisms and their resistance to these antibiotics is increasing. Beta- lactamases are the main responsible for resistance to these antibiotics and the failure of beta-lactam antibiotics in treatment. Therefore, beta-lactamase inhibitors have been developed and combined with beta-lactam antibiotics. These inhibitors are not effective all types of beta-lactamases. In addition, the discovered beta-lactamases are increasing day by day. Characterization of the beta-lactamase type is essential for the detection of the effective antibiotherapy. In this review, the classification of beta-lactamases, the methods used in laboratory detection of beta-lactamases and the current beta-lactamase inhibitors used in treatment will be discussed. ABBREVIATIONS resistance to beta-lactams is through the production of beta- lactamase enzymes [3]. 6-APA: 6-Aminopenicillanic Acid; EUCAST: The European Committee on Antimicrobial Susceptibility Testing; MBLs: Metallo-Beta-Lactamases; EDTA: Ethylene Diaminetetra Acetic Acid particularlyBeta-lactam/beta-lactamase useful for the treatment inhibitor of combinationsinfections caused (BLICs), by organismssuch as piperacillin-tazobactam that produce beta-lactamases or amoxicillin-clavulanate, [5,6]. are INTRODUCTION BETA-LACTAMASES beta-lactam antibiotic, began with AlexanderFleming [1]. The The beta-lactamases breaks the beta-lactam ring and makes The history of penicillin, which was the first discovered beta-lactamases were intended by the name of the strain beta-lactams ring was the common structure in the developed orthe plasmidantibiotic that inactive produced before them, it reaches an example the PBP that targetInitially persists in cephalosporins,penicillin derivatives. monobactams, The beta-lactam carbapenems nucleus, are 6-APAlocated proved in the such enzyme names as PC1 or P99. In 1975, the application of beta-lactamto be the key antibiotic in penicillin group synthesis [2]. and modification.Penicillins, isoelectric focusing for beta-lactamase characterization allowed many more enzymes to be differentiated [7-9]. Beta-lactam antibiotics, whose mechanism of action is inhibition of the last stage of bacterial cell wall synthesis, are the largest family of antimicrobial agents and the most widely used in were facilitated by the use of DNA sequencing. While current clinical practice. Unfortunately, increasing resistance to plasmidThe characterizationmediated enzymes and are classification generally expressedof beta lactamases in Gram- these antibiotics limits their utility [3]. Mechanisms of resistance negativeorganisms basicly, chromosomally located inducible to beta-lactams contain the production of efflux pumps, the expression of beta-lactamases is also extensive [10,11]. modification or reduced production of outer membrane suggestsBeta-lactamases four distinct are molecular evaluated classes: by two A, basic B, C classificationsand D based productionporins (in Gramof beta-lactamase negative bacteria), (an enzyme alterations able to of break Penicillin- down [12]. The molecular classification proposed by Ambler (in 1980 Binding Proteins (the molecular target of beta-lactams) and the Although classes A, C and D enzymes utilize serine for beta- on the amino acid sequencing and the conserved motifs [13]. beta-lactam ring) [4]. One of the primary mechanisms of bacterial Cite this article: Uğraklı S, Doğan M (2018) Overview of Β-Lactamases and Current Techniques for Detecting Beta-Lactamase Mediated Resistance. Ann Clin Med Microbiol 3(1): 1016. Doğan et al. (2018) Email: [email protected] Central and early cefalosporin such as cephaloridine and cephalothin, lactam hydrolysis, class B metalloenzymes that require divalent subgroup 2b contain the TEM-1, TEM-2, and SHV-1 enzymes [19]. zincThe ions second (metal schemeion) for issubstrate named ashydrolysis Bush, Jacoby, [10]. and Medeiros and are strongly inhibited by clavulanic acid and tazobactam. The Subgroup 2be: Include enzymes that are capable of functional classification, which groups different beta-lactamases correlatesaccording tothe their beta-lactamases substrate and with inhibitor phenotypes profiles, in was clinical first inactivating third-generation cephalosporins (ceftazidime, isolatesattempted [13]. in Based1989 andon the then differences improved among in1995. the This enzymes method in generationcefotaxime, cefalosporinsand cefpodoxime) they are asnamed well Extendedas monobactams Spectrum (aztreonam). Because of their board activity against third an important reason for therapy failure with cephalosporins and these groups, they were further divided into several subgroups Beta-lactamases (ESBLs). Organisms that produce ESBLs proceed [14]. The three major groups of enzymes are described by their cephalosporinasessubstrate and inhibitor and profiles:broad spectrumgroup 1 cephalosporinases beta-lactamases that [21].have serious consequences for infection control [20]. Most ESBLs are not well inhibited by clavulanic acid; group 2 penicillinases, can be divided into three groups: TEM, SHV, and CTX-M types TEM types ESBLs: thatare generallyhydrolyze inhibitedpenicillins, by cephalosporins active site-directed and carbapenems beta-lactamase and phenotype. Although TEM-typeTEM-3, beta-lactamases originally reported are most in 1989,often thatinhibitors; are poorly and theinhibited group by 3 almostmetallo-beta-lactamases all beta-lactamcontaining (MBLs) foundwas the in firstE. coli TEM-type and K. pneumoniae, beta-lactamase they that are displayedalso found the in otherESBL moleculesGroup 1 Cephalosporinase[14,15]. speciesSHV of type Gram-negative ESBLs: bacteria with increasing frequency [22]. Group 1 enzymes are cephalosporinases belonging to are shown under the amino acids of SHV-1[22]. molecular class C. AmpC enzymes encoded by both chromosomal Substitutions found in SHV-type derivatives • CTX-M type ESBLs: Because of its predominant acquiredand plasmid genes genes for are AmpC also enzymes,evolving to hence hydrolyze transferable broad-spectrum between cefotaxime activity and the location of its isolation species.cephalosporins These enzymes more efficiently. appeared inTransmissible Enterobacteriaceae plasmids that have lack (Munich) was named CTX-M. These enzymes are not chromosomal AmpC enzymes (Proteus mirabilis, Salmonella spp. ithvery theseclosely two related commonly to TEM isolatedor SHV beta-lactamases and Klebsiella in that they share only approximately 40% identity like Escherichia coli and Shigella spp [16]. spp) or only express low basal level of AmpC [23]. CTX-M type ESBLs possess extraordinary high anotherhydrolytic genuine activity characteristic against cefotaxime of these than enzymes ceftazidime is that suchAmpC as cefoxitin beta-lactamases and cefotetan; are active oxyiminocephalosporins on penicillins but evensuch they[24]. areIn additioninhibited to better the rapidby the hydrolysis beta-lactamase of cefotaxime, inhibitor asmore ceftazidime, active on cephalosporinscefotaxime, and and ceftriaxone. can hydrolyze They cephamycins are usually • tazobactamSubgroup 2br:than byBroad-spectrum sulbactam and beta-lactamasesclavulanat [25]. that [17].resistant to inhibition by clavulanic acid [15]. They have a high affinity for aztreonam, in contrast to the class A cephalosporinases • Subgroup 2ber: Contains TEM enzymes that combine an AmpC beta-lactamases encoded by chromosomal are have acquired resistance to clavulanic acid do not paytake to beta-lactam resistance, but in some organisms aminoextended acid spectrum substitutions with relative common resistance to both the to clavulanicESBL and (expressedSerratia marcescens, principally atCitrobacter very low grades.These freundii, Morganella enzymes morganii,generally acid inhibition. These group includesTEM-50, which had Providencia stuartii and especially Enterobacter cloacae inhibitor-resistant TEMs, was recently identified. This ) they can it also conferred a slight resistance to the expanded- spectrumenzyme was cephalosporins resistant to [26].inhibition by clavulanate, but acidbe provaked ]. The indicuble under certainenzymes situations cause clinical