β- Lactam Antibiotics Renaissance Wenling Qin ,Mauro Panunzio and Stefano Biondi Antibiotics 2014, 3, 193-215
Presented byNeeraj Chauhan
M.Sc 2nd yearDMBT
AntibioticsAn antibiotic is an agent that either kills or inhibits the
growth of a microorganism
Classification of Antibiotics
Based on mode of Action
Cell Wall Synthesis
Protein Synthesis
DNA Synthesis
RNA synthesis
Based on their spectrum of action
Broad-spectrum
Narrow Spectrum
Types of AntibioticsAntibioticsBeta-Lactams
Macrolides
Fluoroquinolones
Tetracyclines
Aminoglycosides
β-lactam antibioticsContain β-lactam ring
β-lactam (beta-lactam) ring is a four-membered lactam Active against both Gram positive and Gram negative
pathogens
Includes penicillin derivatives (penams), cephalosporins (cephems), monobactams, and carbapenems
β-lactam ring
N
O
Adverse effectsAdverse drug reactionsdiarrhea, nausea, rash, urticaria, superinfection (including candidiasis) fever, vomiting, erythema, dermatitis, angioedemaPain and inflammation at the injection site also common
Allergy/hypersensitivityurticaria, anaphylaxis, interstitial nephritis
Mode of action:β-lactams disrupt the synthesis of bacterial cell wall
mimic the structure of D-Ala-D-Ala link bind to the active site of PBPs
PBP recognise the D-Ala-D-Ala sequence of the NAMA peptide side chain
disrupt the cross-linking process.
Mechanism of β-Lactam Drugs
N
O
RS
Me
Me
COOHSER
OH
H
N
RS
Me
Me
COOHSER
O
H
O
HN
RS
Me
Me
COOHSER
O
O
The PBP is now covalently bound by the drug and cannot perform the cross linking action
The tetrahedral intermediate collapses, the amide bond is broken, and the nitrogen is reduced
The hydroxyl attacks the amide and forms a tetrahedral intermediate
Beta–lactam Resistance
β-lactamaseChanges in active site of PBPs
Decreased expression of
outer membrane proteins (OMPs)
Efflux pumps
β-LactamasesProvide resistance to β-lactam antibiotics
Hydrolyze β-lactam ringdeactivate drug
Especially prevalent in Gram (-) bacteria.
To counter bacterial resistance, there is a need of development of new antibiotics
In particular, two types of strains have led to the need for developing new drugs:
multidrug-resistant strains (MDR) extremely drug-resistant strains (XDR)
In antibiotic development ,novel β-lactam antibiotics or β-lactamase inhibitors play a significant role
Avenues: Identify novel β-lactams Identify novel β-lactamase inhibitors
β-Lactamase InhibitorsUsed in conjunction with β-Lactam antibioticsExamples:
Clavulanic acid+ amoxicillin or ticarcillin Sulbactam + ampicillin or cefoperazone Tazobactam + piperacillin
Efficacy against β-lactamases class A β-lactamases- effective class C enzymes- less effective class B and most class D enzymes- inactive
Avibactam, MK-7655, MK-8712, and RPX7009 Able to inhibit class A and C β-lactamases, such. Among these, only avibactam and MK-7655 are under development
Sulbactam
Combinations of β-lactam antibiotics and β-lactamase inhibitors Commercially available
(i) Amoxicillin-clavulanate. first β-lactam-β-lactamase inhibitor combination introduced in 1981 in the United Kingdom and in 1984 in the United
States, and only combination available for oral use. Amoxicillin active against streptococci, enterococci, E. coli, and Listeria
spp Addition of clavulanate expands amoxicillin's spectrum
penicillinase-producing S. aureus, H. influenzae, Moraxella catarrhalis, Bacteroides spp., N. gonorrhoeae, E. coli, Klebsiella spp., and P. mirabilis
an oral equivalent of ampicillin-sulbactam or ticarcillin-clavulanate in the treatment of skin, soft tissue, abdominal infections.
Intravenous formulations of amoxicillin-clavulanate available in Europe
(ii) Ticarcillin-clavulanate Introduced in 1985 first combination for parenteral administration. ticarcillin effective against non-β-lactamase-producing
Haemophilus spp., E. coli, Proteus spp., Enterobacter spp., Morganella spp., Providencia spp., and P. aeruginosa.
ticarcillin + clavulanate increase activity against β-lactamase-producing staphylococci, E. coli, H. influenzae, Klebsiella spp.,
Proteus spp., Pseudomonas spp., Providencia spp., N. gonorrhoeae, Moraxella catarrhalis, and Bacteroides spp
Exhibits activity against multidrug-resistant
(iii) Ampicillin-sulbactam. Ampicillin activity against Streptococci, Enterococci, Listeria spp., and strains of S. aureus, H.
influenzae, E. coli, P. mirabilis, Salmonella spp., and Shigella spp. that are devoid of β-lactamases
In combination with sulbactam, the activity extends to β-lactamase-containing S. aureus, H. influenzae, M. catarrhalis, E. coli, Proteus spp., Klebsiella spp., and anaerobes
combination of ampicillin at 2.0 g + sulbactam at 1.0 g ideal therapy for polymicrobial infections such as abdominal and
gynecological surgical infections, aspiration pneumonia, odontogenic abscesses, and diabetic foot infections.
Unfortunately, the resistance to ampicillin-sulbactam among clinical isolates of E. coli is increasing
(iv) Piperacillin-tazobactam. Introduced in United States in 1993 Piperacillin broad-spectrum penicillin that is bactericidal against many Gram-
positive and Gram-negative aerobes and anaerobes Piperacillin demonstrates activity against P. aeruginosa, pneumococci, streptococci,
anaerobes, and Enterococcus faecalis, and this activity is retained in combination with tazobactam .
Tazobactam extend piperacillin's activity β-lactamase producing strains of Enterobacteriaceae, H. influenzae, N.
gonorrhoeae, and M. catarrhalis and has the potential to lower MICs against these strains expressing ESBLs
CXA-101 (Zerbaxa) ceftolozane + tazobactam Ceftolozane- cephalosporin
Active against MDR P. aeruginosa Have enhanced affinity for the PBPs Stable to β-lactamase AmpCs
Tazobactam- sulfone penam β-lactamase inhibitor Restore susceptibility of
93% of ESBL producers 95% of the AmpC producer
Used to treat cUTI, including kidney infection (pyelonephritis). Used with metronidazole to treat cIAI Dosage-
1.5 g (1 g/0.5 g) every 8 hours intravenous in patients 18 years or older .
CAZ104 (AVYCAZ) Ceftazidime + avibactam Ceftazidime
third-generation cephalosporin good activity against Gram-negative pathogens
Avibactam Inhibits class A β-lactamases;including ESBLs and KPCs less active against AmpCs Inactive towards metallo-β-lactamases
For treatment of cUTI including pyelonephritis caused by: Escherichia coli, Klebsiella pneumoniae, Citrobacter koseri, Enterobacter aerogenes,
Enterobacter cloacae, Citrobacter freundii, Proteus spp. and Pseudomonas aeruginosa.
Dosage 2.5g (2g ceftazidime and 0.5g avibactam) given every eight hours intravenous for 5 to 14 days.
side effects include vomiting, nausea, constipation and anxiety.
CEFTAZIDIME
AVIBACTAM
Conclusions β-lactam antibiotics
play important role in treatment of multidrug resistant pathogensWidely prescribed because of efficacy and safety profile
Interest for novel β-lactam antibiotics or β-lactamase inhibitors has boosted
Goal is to achieve antibacterial efficacy against multidrug resistant pathogens.
Two new families of β-lactamase inhibitors emerge Diazabicycooctanes (DBOs) and boronic acids
Combine with cephalosporins and carbapenems show activity against β-lactamase-producing Gram-negative bacteria
Inhibitors against class A (ESBL, KPC), class D (OXA) and class B (NDM) β-lactamases require