• Extended spectrum Beta-lactamase are enzymes belongs to molecular class ‘A’ or ‘D’ and functional group 2b e and 2d. These enzymes hydrolyses penicillin, cephalosporin (1^st, 2^nd and 3^rd generaion) including Aztreonam. However they are inactivated by clavulinic acid ad cephamycin (cephoxitine and cephotetan).

Types of ESBL

1. TEM type ESBL (Temoneira)

• This type of ESBL is commonly produced by coli and Klebsiella pneumonia, but also has been noted in Neisseria gonorrhoae and Hemophilus influenza.
• All TEM type ESBLs are derived from TEM-1 and TEM-2
• TEM-1 can hydrolyze ampicillin with greater extent but has negligible activity against extended spectrum cephalosporins. It is inhibited by clavulinic acid
• TEM-2 has same hydrolytic profile as TEM-1 but has different isoelectric point.
• There are more than 140 TEM type ESBl. However most common type of TEM ESBL are TEM-10, TEM-12 and TEM-26
• Amino acid substitution in active site of enzyme is responsible for ESBL, which results in allowing excess amount of Oxy-imino-β-lactams.

2. SHV type ESBL (sulfhydryl variable)

• SHV type ESBL resembles 80% to type TEM
• SHV type is usually produced by Klebsiella pneumonia and other enterobacteriaceae.
• SHV type are produced as a result of amino acid substitution at position 238 and 240.
• More than 80 different types of SHV have been identified. Most common SHV type are SHV-5 and SHV-12

3. CTX-M type ESBL (Cefotaximases)

• CTX-M type ESBL shows more affinity towards cefotaxims than other Oxyimino-β-lactam antibiotics.
• Most common type of CTX-M are CTX-M-2, CTX-M-3, CTX-M-14, CTX-M-15
• They are usually produced by coli and Salmonella enterica serovar Typhimurium

4. OXA type ESBl (Oxacillinases)

• OXA type ESBl are usually produced by Pseudomonas aeroginosa but have been detected in other gram negative bacteria also.
• This OXA type ESBL belongs to class ‘D’ and functional class 2d.
• It is characterized by hydrolysis rate for cloxacillin and oxacillin greater than 50% than for benzylpenicillin.
• They show reduced inhibition to clavulinic acid
• Most OXA type beta-lactamase do not hydrolyse the extended spectrum cephalosporin to significant degree and are not regarded as ESBLs. However OXA-10 hydrolyses cefotaxime, ceftriaxone and aztreonam.
• Most common type OXA type ESBL are is OXA-11, OXA-14, OXA-16, OXA-17, OXA-19, OXA-28, OXA-31, OXA-32, OXA_35, OXA-45

5. PER type ESBL:

• It share only about 25-27% homology with TEM and SHV type ESBL
• PER-1 can effectively hydrolyse penicillins and cephalosporins and is susceptible to clavulinic acid
• PER type ESBl is produced by Pseudomonas aeroginosa, Salmonella enterica serovar Typhimurium , Acinetobacter, Vibrio cholera, Klebsiella pneumonia, Proteus mirabilis

6. Other ESBL types are:

• VEB
• BES-1
• VIM-1
• GES
• TLA
• IBC
• SFO

ESBL (Extended Spectrum beta-Lactamases) and types

The post ESBL (Extended Spectrum beta-Lactamases) and types  appeared first on Online Biology Notes.