Beta-lactam antibiotic - AbsoluteAstronomy.com

β-Lactam antibiotics are a broad class of antibiotic

Antibiotic

An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...

s, consisting of all antibiotic agents that contains a β-lactam

Beta-lactam

A β-lactam ring, is a four-membered lactam. It is named as such, because the nitrogen atom is attached to the β-carbon relative to the carbonyl...

nucleus in its molecular structure. This includes penicillin

Penicillin

Penicillin is a group of antibiotics derived from Penicillium fungi. They include penicillin G, procaine penicillin, benzathine penicillin, and penicillin V....

derivatives (penam

Penam

Penams are a subclass of the broader β-lactam family of antibiotics and related compounds. Penams contain a β-lactam ring fused to a 5-membered ring, where one of the atoms in the ring is a sulfur and the ring is fully saturated. Penicillin is a member of this family of compounds....

s), cephalosporin

Cephalosporin

The cephalosporins are a class of β-lactam antibiotics originally derived from Acremonium, which was previously known as "Cephalosporium".Together with cephamycins they constitute a subgroup of β-lactam antibiotics called cephems.-Medical use:...

s (cephem

Cephem

Cephems are a sub-group of beta-lactam antibiotics including cephalosporins and cephamycins....

s), monobactams, and carbapenem

Carbapenem

Carbapenems are a class of β-lactam antibiotics with a broad spectrum of antibacterial activity. They have a structure that renders them highly resistant to most β-lactamases...

s. β-Lactam antibiotics work by inhibiting cell wall

Cell wall

The cell wall is the tough, usually flexible but sometimes fairly rigid layer that surrounds some types of cells. It is located outside the cell membrane and provides these cells with structural support and protection, and also acts as a filtering mechanism. A major function of the cell wall is to...

synthesis by the bacterial organism and are the most widely used group of antibiotics.

Up until 2003, when measured by sales, more than half of all commercially available antibiotics in use were β-lactam compounds.

Bacteria often develop resistance to β-lactam antibiotics by synthesizing a β-lactamase

Beta-lactamase

Beta-lactamases are enzymes produced by some bacteria and are responsible for their resistance to beta-lactam antibiotics like penicillins, cephamycins, and carbapenems . These antibiotics have a common element in their molecular structure: a four-atom ring known as a beta-lactam...

, an enzyme that attacks the β-lactam ring. To overcome this resistance, β-lactam antibiotics are often given with β-lactamase inhibitor

Beta-lactamase inhibitor

A beta-lactamase inhibitor is a drug given in conjunction with a beta-lactam antibiotic. Although the inhibitor does not usually have significant antibiotic activity on its own, it inhibits activity of beta-lactamase, a protein that confers resistance of beta-lactam antibiotics to...

s such as clavulanic acid

Clavulanic acid

Clavulanic acid is a competitive β-lactamase inhibitor combined with penicillin group antibiotics to overcome certain types of antibiotic resistance. It is used to overcome resistance in bacteria that secrete β-lactamase, which otherwise inactivates most penicillins...

Medical use

β-Lactam antibiotics are indicated for the prophylaxis and treatment of bacteria

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

l infections caused by susceptible organisms. At first, β-lactam antibiotics were mainly active only against Gram-positive

Gram-positive

Gram-positive bacteria are those that are stained dark blue or violet by Gram staining. This is in contrast to Gram-negative bacteria, which cannot retain the crystal violet stain, instead taking up the counterstain and appearing red or pink...

bacteria, yet the recent development of broad-spectrum β-lactam antibiotics active against various Gram-negative

Gram-negative

Gram-negative bacteria are bacteria that do not retain crystal violet dye in the Gram staining protocol. In a Gram stain test, a counterstain is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color...

organisms has increased their usefulness.

Adverse drug reactions

Common adverse drug reactions (ADRs) for the β-lactam antibiotics include diarrhea, nausea, rash,urticaria

Urticaria

Urticaria is a kind of skin rash notable for pale red, raised, itchy bumps. Hives is frequently caused by allergic reactions; however, there are many non-allergic causes...

, superinfection

Superinfection

In virology, superinfection is the process by which a cell, that has previously been infected by one virus, gets coinfected with a different strain of the virus, or another virus at a later point in time. Viral superinfections of serious conditions can lead to resistant strains of the virus, which...

(including candidiasis

Candidiasis

Thrush redirects here. For the hoof infection see Thrush .Candidiasis or thrush is a fungal infection of any of the Candida species , of which Candida albicans is the most common...

).

Infrequent ADRs include fever, vomiting, erythema

Erythema

Erythema is redness of the skin, caused by hyperemia of the capillaries in the lower layers of the skin. It occurs with any skin injury, infection, or inflammation...

, dermatitis, angioedema

Angioedema

Angioedema or Quincke's edema is the rapid swelling of the dermis, subcutaneous tissue, mucosa and submucosal tissues. It is very similar to urticaria, but urticaria, commonly known as hives, occurs in the upper dermis...

,pseudomembranous colitis

Pseudomembranous colitis

Pseudomembranous colitis, a cause of antibiotic-associated diarrhea , is an infection of the colon. It is often, but not always, caused by the bacterium Clostridium difficile. Because of this, the informal name C. difficile colitis is also commonly used. The illness is characterized by...

.

Pain and inflammation at the injection site is also common for parenteral

Parenteral

Parenteral is a route of administration that involves piercing the skin or mucous membrane. Parenteral nutrition refers to providing nutrition via the veins.-Etymology:...

ly administered β-lactam antibiotics.

Allergy/hypersensitivity

Immunologically mediated adverse reactions to any β-lactam antibiotic may occur in up to 10% of patients receiving that agent (a small fraction of which are truly IgE-mediatedallergic

Allergy

An Allergy is a hypersensitivity disorder of the immune system. Allergic reactions occur when a person's immune system reacts to normally harmless substances in the environment. A substance that causes a reaction is called an allergen. These reactions are acquired, predictable, and rapid...

reactions, see amoxicillin rash).Anaphylaxis

Anaphylaxis

Anaphylaxis is defined as "a serious allergic reaction that is rapid in onset and may cause death". It typically results in a number of symptoms including throat swelling, an itchy rash, and low blood pressure...

will occur in approximately 0.01% of patients. There is perhaps a 5%-10% cross-sensitivity between penicillin-derivatives, cephalosporins, and carbapenems; but this figure has been challenged by various investigators.

Nevertheless, the risk of cross-reactivity is sufficient to warrant the contraindication of all β-lactam antibiotics in patients with a history of severe allergic reactions (urticaria

Urticaria

Urticaria is a kind of skin rash notable for pale red, raised, itchy bumps. Hives is frequently caused by allergic reactions; however, there are many non-allergic causes...

, anaphylaxis, interstitial nephritis

Interstitial nephritis

Interstitial nephritis is a form of nephritis affecting the interstitium of the kidneys surrounding the tubules...

) to any β-lactam antibiotic.

A Jarisch-Herxheimer reaction

Herxheimer reaction

The Herxheimer reaction resembles bacterial sepsis and can occur after initiation of antibiotic therapy or treatment of tick-borne relapsing fever. An association has been found between the release of heat-stable proteins from spirochetes and the reaction. The same can be true for candida die-off...

may occur after initial treatment of aspirochetal infection such as syphilis

Syphilis

Syphilis is a sexually transmitted infection caused by the spirochete bacterium Treponema pallidum subspecies pallidum. The primary route of transmission is through sexual contact; however, it may also be transmitted from mother to fetus during pregnancy or at birth, resulting in congenital syphilis...

with a β-lactam antibiotic.

Mode of action

β-Lactam antibiotics are bacteriocidal, and act by inhibiting the synthesis of the peptidoglycan

Peptidoglycan

Peptidoglycan, also known as murein, is a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of bacteria , forming the cell wall. The sugar component consists of alternating residues of β- linked N-acetylglucosamine and N-acetylmuramic acid...

layer of bacterial cell wall

Cell wall

s. The peptidoglycan layer is important for cell wall structural integrity, especially in Gram-positive

Gram-positive

organisms, being the outermost and primary component of the wall. The final transpeptidation step in the synthesis of the peptidoglycan is facilitated by transpeptidase

Transpeptidase

A transpeptidase is a bacterial enzyme that cross-links the peptidoglycan chains to form rigid cell walls. This enzyme is also known by several other names including DD-peptidase, DD-transpeptidase, D-alanyl-D-alanine carboxypeptidase and serine-type D-Ala-D-Ala carboxypeptidase...

s known as penicillin-binding proteins (PBPs). PBPs vary in their affinity for binding penicillin or other β-lactam antibiotics. The amount of PBPs varies among bacterial species.

β-Lactam antibiotics block not only the division of bacteria, including cyanobacteria, but also the division of cyanelles, the photosynthetic

Photosynthesis

Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...

organelle

Organelle

In cell biology, an organelle is a specialized subunit within a cell that has a specific function, and is usually separately enclosed within its own lipid bilayer....

s of the glaucophyte

Glaucophyte

The glaucophytes, also known as glaucocystophytes or glaucocystids, are a small group of freshwater microscopic algae. Together with the red algae and green algae plus land plants , they form the Archaeplastida...

s, and the division of chloroplast

Chloroplast

Chloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.Chloroplasts are green...

s of bryophyte

Bryophyte

Bryophyte is a traditional name used to refer to all embryophytes that do not have true vascular tissue and are therefore called 'non-vascular plants'. Some bryophytes do have specialized tissues for the transport of water; however since these do not contain lignin, they are not considered to be...

s. In contrast, they have no effect on the plastid

Plastid

Plastids are major organelles found in the cells of plants and algae. Plastids are the site of manufacture and storage of important chemical compounds used by the cell...

s of the highly developed vascular plant

Vascular plant

Vascular plants are those plants that have lignified tissues for conducting water, minerals, and photosynthetic products through the plant. Vascular plants include the clubmosses, Equisetum, ferns, gymnosperms and angiosperms...

s. This is supporting the endosymbiotic theory

Endosymbiotic theory

The endosymbiotic theory concerns the mitochondria, plastids , and possibly other organelles of eukaryotic cells. According to this theory, certain organelles originated as free-living bacteria that were taken inside another cell as endosymbionts...

and indicates an evolution

Evolution

Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

of plastid division in land plant

Plant

Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...

s.

β-Lactam antibiotics are analogues of -alanyl--alanine — the terminal amino acid

Amino acid

Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...

residues on the precursor NAM/NAG-peptide subunits of the nascent peptidoglycan layer. The structural similarity between β-lactam antibiotics and -alanyl--alanine facilitates their binding to the active site of penicillin-binding proteins (PBPs). The β-lactam nucleus of the molecule irreversibly binds to (acylates) the Ser₄₀₃ residue of the PBP active site. This irreversible inhibition of the PBPs prevents the final crosslinking (transpeptidation) of the nascent peptidoglycan layer, disrupting cell wall synthesis.

Under normal circumstances, peptidoglycan precursors signal a reorganisation of the bacterial cell wall and, as a consequence, trigger the activation of autolytic cell wall hydrolase

Hydrolase

In biochemistry, a hydrolase is an enzyme that catalyzes the hydrolysis of a chemical bond. For example, an enzyme that catalyzed the following reaction is a hydrolase:-Nomenclature:...

s. Inhibition of cross-linkage by β-lactams causes a build-up of peptidoglycan precursors, which triggers the digestion of existing peptidoglycan by autolytic hydrolases without the production of new peptidoglycan. As a result, the bactericidal action of β-lactam antibiotics is further enhanced.

Modes of resistance

By definition, all β-lactam antibiotics have a β-lactam ring in their structure. The effectiveness of these antibiotics relies on their ability to reach the PBP intact and their ability to bind to the PBP. Hence, there are two main modes of bacterial resistance to β-lactams:

Enzymatic hydrolysis of the β-lactam ring

If the bacterium produces the enzyme

Enzyme

Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

β-lactamase

Beta-lactamase

or the enzyme penicillinase, the enzyme will hydrolyse

Hydrolysis

Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...

the β-lactam ring of the antibiotic, rendering the antibiotic ineffective. (An example such enzyme is NDM-1, discovered in 2009.) The genes encoding these enzymes may be inherently present on the bacterial chromosome

Chromosome

A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...

or may be acquired via plasmid

Plasmid

In microbiology and genetics, a plasmid is a DNA molecule that is separate from, and can replicate independently of, the chromosomal DNA. They are double-stranded and, in many cases, circular...

transfer (plasmid mediated resistance

Plasmid mediated resistance

Plasmid-mediated resistance is the transfer of antimicrobial-resistant coding genes which are carried on plasmids. The plasmids can be transferred between prokaryotes through horizontal gene transfer...

), and β-lactamase gene expression

Gene expression

Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product. These products are often proteins, but in non-protein coding genes such as ribosomal RNA , transfer RNA or small nuclear RNA genes, the product is a functional RNA...

may be induced by exposure to β-lactams.

The production of a β-lactamase by a bacterium does not necessarily rule out all treatment options with β-lactam antibiotics. In some instances, β-lactam antibiotics may be co-administered with a β-lactamase inhibitor

Beta-lactamase inhibitor

. For example, Augmentin (FGP) is made of amoxicillin

Amoxicillin

Amoxicillin , formerly amoxycillin , and abbreviated amox, is a moderate-spectrum, bacteriolytic, β-lactam antibiotic used to treat bacterial infections caused by susceptible microorganisms. It is usually the drug of choice within the class because it is better absorbed, following oral...

, a β-lactam antibiotic, and clavulanic acid

Clavulanic acid

, a β-lactamase inhibitor. The clavulanic acid is designed to overwhelm all β-lactamase enzymes, bind irreversibly to them, and effectively serve as an antagonist

Receptor antagonist

A receptor antagonist is a type of receptor ligand or drug that does not provoke a biological response itself upon binding to a receptor, but blocks or dampens agonist-mediated responses...

so that the amoxicillin is not affected by the β-lactamase enzymes.

However, in all cases where infection with β-lactamase-producing bacteria is suspected, the choice of a suitable β-lactam antibiotic should be carefully considered prior to treatment. In particular, choosing appropriate β-lactam antibiotic therapy is of upmost importance against organisms with inducible β-lactamase expression. If β-lactamase production is inducible, then failure to use the most appropriate β-lactam antibiotic therapy at the onset of treatment will result in induction of β-lactamase production, thereby making further efforts with other β-lactam antibiotics more difficult.

Possession of altered penicillin-binding proteins

As a response to increased efficacy of β-lactams, some bacteria have changed the proteins to which β-lactam antibiotics bind. β-Lactams cannot bind as effectively to these altered PBPs, and, as a result, the β-lactams are less effective at disrupting cell wall synthesis. Notable examples of this mode of resistance include methicillin

Methicillin

Meticillin or methicillin is a narrow-spectrum beta-lactam antibiotic of the penicillin class. It should not be confused with the antibiotic metacycline.-History:Methicillin was developed by Beecham in 1959...

-resistant Staphylococcus aureus (MRSA) and penicillin-resistant Streptococcus pneumoniae
Streptococcus pneumoniae
Streptococcus pneumoniae, or pneumococcus, is Gram-positive, alpha-hemolytic, aerotolerant anaerobic member of the genus Streptococcus. A significant human pathogenic bacterium, S...

. Altered PBPs do not necessarily rule out all treatment options with β-lactam antibiotics.

Nomenclature

β-Lactams are classified according to their core ring structures. For example:

β-Lactams fused to thiazolidine
Thiazolidine
Thiazolidines are a class of heterocyclic organic compounds with a 5-membered saturated ring with a thioether group and an amine group in the 1 and 3 positions, respectively. It is a sulfur analogue of oxazolidine. The drug pioglitazone contains a thiazolidine ring. It is a drug usually indicated...

rings are named penam
Penam
Penams are a subclass of the broader β-lactam family of antibiotics and related compounds. Penams contain a β-lactam ring fused to a 5-membered ring, where one of the atoms in the ring is a sulfur and the ring is fully saturated. Penicillin is a member of this family of compounds....

s.
β-Lactams fused to 2,3-dihydrothiazole
Thiazole
Thiazole, or 1,3-thiazole, is a heterocyclic compound that contains both sulfur and nitrogen; the term 'thiazole' also refers to a large family of derivatives. Thiazole itself is a pale yellow liquid with a pyridine-like odor and the molecular formula C3H3NS...

rings are named penem
Penem
A penem is a type of unsaturated β-lactam.An example is faropenem.Penems are similar in structure to carbapenems. However, where penems have a sulfur, carbapenems have another carbon....

s.
β-Lactams fused to 2,3-dihydro-1H-pyrrole
Pyrrole
Pyrrole is a heterocyclic aromatic organic compound, a five-membered ring with the formula C4H4NH. It is a colourless volatile liquid that darkens readily upon exposure to air. Substituted derivatives are also called pyrroles, e.g., N-methylpyrrole, C4H4NCH3...

rings are named carbapenem
Carbapenem
Carbapenems are a class of β-lactam antibiotics with a broad spectrum of antibacterial activity. They have a structure that renders them highly resistant to most β-lactamases...

s.
β-Lactams fused to 3,6-dihydro-2H-1,3-thiazine
Thiazine
Thiazines are organic compounds containing a ring of four carbon, one nitrogen and one sulfur atom. Chemicals that include thiazine are used for dyes, tranquilizers and insecticides.-See also:*Methylene blue*Phenothiazine*Heterocyclic compound*Morpholine...

rings are named cephem
Cephem
Cephems are a sub-group of beta-lactam antibiotics including cephalosporins and cephamycins....

s.
β-Lactams not fused to any other ring are named monobactams.

Penicillins (Penams)

Semisynthetic penicillins are prepared starting from the penicillin nucleus 6-APA

6-APA

6-APA is the chemical compound -6-aminopenicillanic acid.-Use:6-APA is the core of penicillins. It is obtained from the fermentation brew of the Penicillium mold and used as the main starting block for the preparation of numerous semisynthetic penicillins.-Manufacture:This useful compound is made...

Narrow-spectrum

β-lactamase sensitive
- benzathine penicillin
- benzylpenicillin
  Benzylpenicillin
  Benzylpenicillin, commonly known as penicillin G, is the gold standard type of penicillin. 'G' in the name 'Penicillin G' refers to 'Gold Standard'. Penicillin G is typically given by a parenteral route of administration because it is unstable in the hydrochloric acid of the stomach...
  
  (penicillin G)
- phenoxymethylpenicillin
  Phenoxymethylpenicillin
  Phenoxymethylpenicillin, commonly known as penicillin V, is a penicillin antibiotic that is orally active. It is less active than benzylpenicillin against Gram-negative bacteria. Phenoxymethylpenicillin is more acid-stable than benzylpenicillin, which allows it to be given orally...
  
  (penicillin V)
- procaine penicillin

Penicillinase-resistant penicillins
- methicillin
  Methicillin
  Meticillin or methicillin is a narrow-spectrum beta-lactam antibiotic of the penicillin class. It should not be confused with the antibiotic metacycline.-History:Methicillin was developed by Beecham in 1959...
- oxacillin
  Oxacillin
  Oxacillin sodium is a narrow spectrum beta-lactam antibiotic of the penicillin class.It was developed by Beecham.-Uses:...
- nafcillin
- cloxacillin
  Cloxacillin
  Cloxacillin is a semisynthetic antibiotic in the same class as penicillin. Cloxacillin was discovered and developed by Beecham. It is sold under a number of trade names, including Cloxapen, Cloxacap, Tegopen and Orbenin....
- dicloxacillin
  Dicloxacillin
  Dicloxacillin is a narrow-spectrum beta-lactam antibiotic of the penicillin class. It is used to treat infections caused by susceptible Gram-positive bacteria. It is active against beta-lactamase-producing organisms such as Staphylococcus aureus, which would otherwise be resistant to most...
- flucloxacillin
  Flucloxacillin
  Flucloxacillin or floxacillin is a narrow-spectrum beta-lactam antibiotic of the penicillin class. It is used to treat infections caused by susceptible Gram-positive bacteria. Unlike other penicillins, flucloxacillin has activity against beta-lactamase-producing organisms such as Staphylococcus...

β-lactamase-resistant penicillins
- temocillin
  Temocillin
  Temocillin is a β-lactamase resistant penicillin introduced by Beecham, marketed by Eumedica Pharmaceuticals as Negaban primarily for the treatment of multiresistant Gram negative bacteria.It is a carboxypenicillin.-Pharmacology:...

Extended-spectrum

azlocillin
Azlocillin
Azlocillin is an acylampicillin antibiotic with an extended spectrum of activity and greater in vitro potency than the carboxy penicillins.Azlocillin is similar to mezlocillin and piperacillin...
carbenicillin
Carbenicillin
Carbenicillin is a bacteriolytic antibiotic belonging to the carboxypenicillin subgroup of the penicillins. It was discovered by scientists at Beecham and marketed as Pyopen. It has Gram-negative coverage which includes Pseudomonas aeruginosa but limited Gram-positive coverage...
ticarcillin
Ticarcillin
Ticarcillin is a carboxypenicillin. It is almost invariably sold and used in combination with clavulanate as Timentin. Because it is a penicillin, it also falls within the larger class of beta-lactam antibiotics. Its main clinical use is as an injectable antibiotic for the treatment of...
mezlocillin
Mezlocillin
Mezlocillin is a broad-spectrum penicillin antibiotic. It is active against both Gram-negative and some Gram-positive bacteria. Unlike most other extended spectrum penicillins, it is excreted by the liver, therefore it is useful for biliary tract infections, such as ascending colangitis.-Mechanism...
piperacillin
Piperacillin
Piperacillin is an extended spectrum beta-lactam antibiotic of the ureidopenicillin class.It is normally used together with a beta-lactamase inhibitor such as tazobactam. The combination drug piperacillin/tazobactam is commercially available as e.g. Tazocin, Zosyn, Brodactam, Piptaz and as Trezora...

Cephalosporins (Cephems)

First generation

Moderate spectrum.

cephalexin
cephalothin
cefazolin
Cefazolin
Cefazolin , also known as cefazoline or cephazolin, is a first-generation cephalosporin antibiotic.The drug is usually administrated by either intramuscular injection or intravenous infusion .-Indications:Cefazolin is mainly used to treat bacterial infections of the skin...

Second generation

Moderate spectrum with anti-Haemophilus
Haemophilus
Not to be confused with Haemophilia.Haemophilus is a genus of Gram-negative, pleomorphic, coccobacilli bacteria belonging to the Pasteurellaceae family. While Haemophilus bacteria are typically small coccobacilli, they are categorized as pleomorphic bacteria because of the wide range of shapes they...

activity.

cefaclor
Cefaclor
Cefaclor, also known as cefachlor or cefaclorum , is a second-generation cephalosporin antibiotic used to treat certain infections caused by bacteria such as pneumonia and ear, lung, skin, throat, and urinary tract infections.- Indications:Cefaclor belongs to the family of antibiotics known as the...
cefuroxime
Cefuroxime
Cefuroxime is a second-generation cephalosporin antibiotic that has been widely available in the USA as Ceftin since 1977. GlaxoSmithKline sells the antibiotic in the United Kingdom under the name Zinnat.-Indications:As for the other cephalosporins, although as a...
cefamandole
Cefamandole
Cefamandole is a second-generation broad-spectrum cephalosporin antibiotic. The clinically used form of cefamandole is the formate ester cefamandole nafate, a prodrug which is administered parenterally....

Second generation cephamycins

Moderate spectrum with anti-anaerobic activity.

cefotetan
Cefotetan
Cefotetan is an injectable antibiotic of the cephamycin type for prophylaxis and treatment of bacterial infections. It is often grouped together with second-generation cephalosporins and has a similar antibacterial spectrum, but with additional anti-anaerobe coverage.Cefotetan was developed by...
cefoxitin
Cefoxitin
Cefoxitin is a cephamycin antibiotic developed by Merck & Co., Inc., often grouped with the second−generation cephalosporins. It is sold under the brand name Mefoxin.- Microbiology :...

Third generation

Broad spectrum.

ceftriaxone
Ceftriaxone
Ceftriaxone is a third-generation cephalosporin antibiotic. Like other third-generation cephalosporins, it has broad spectrum activity against Gram-positive and Gram-negative bacteria. In most cases, it is considered to be equivalent to cefotaxime in terms of safety and efficacy...
cefotaxime
Cefotaxime
Cefotaxime is a third-generation cephalosporin antibiotic. Like other third-generation cephalosporins, it has broad spectrum activity against Gram positive and Gram negative bacteria...
cefpodoxime
Cefpodoxime
Cefpodoxime is an oral third generation cephalosporin antibiotic. It is marketed as the prodrug cefpodoxime proxetil by Pharmacia & Upjohn under the trade name Vantin. It is active against most Gram positive and Gram negative organisms. Notable exceptions include Pseudomonas aeruginosa,...

ATDOX-200
cefixime
Cefixime
Cefixime is an oral third generation cephalosporin antibiotic. Cefixime is a cephalosporin antibiotic used to treat infections caused by bacteria such as pneumonia; bronchitis; gonorrhea; and ear, lung, throat, and urinary tract infections...

Broad spectrum with anti-Pseudomonas
Pseudomonas
Pseudomonas is a genus of gammaproteobacteria, belonging to the family Pseudomonadaceae containing 191 validly described species.Recently, 16S rRNA sequence analysis has redefined the taxonomy of many bacterial species. As a result, the genus Pseudomonas includes strains formerly classified in the...

activity.

ceftazidime
Ceftazidime
Ceftazidime is a third-generation cephalosporin antibiotic. Like other third-generation cephalosporins, it has broad spectrum activity against Gram-positive and Gram-negative bacteria. Unlike most third-generation agents, it is active against Pseudomonas aeruginosa, however it has weaker activity...

Fourth generation

Broad spectrum with enhanced activity against Gram positive bacteria and β-lactamase stability.

cefepime
Cefepime
Cefepime is a fourth-generation cephalosporin antibiotic developed in 1994. Cefepime has an extended spectrum of activity against Gram-positive and Gram-negative bacteria, with greater activity against both Gram-negative and Gram-positive organisms than third-generation agents...
cefpirome
Cefpirome
Cefpirome is a fourth-generation cephalosporin. Trade names include Cefrom, Keiten, Broact, Cefir. Cefpirome is considered highly active against Gram-negative bacteria, including Pseudomonas aeruginosa, and Gram-positive bacteria....

Carbapenems and Penems

Broadest spectrum of β-lactam antibiotics.

imipenem
Imipenem
Imipenem is an intravenous β-lactam antibiotic developed in 1980. It has an extremely broad spectrum of activity.Imipenem belongs to the subgroup of carbapenems. It is derived from a compound called thienamycin, which is produced by the bacterium Streptomyces cattleya...

(with cilastatin
Cilastatin
Cilastatin is a chemical compound which inhibits the human enzyme dehydropeptidase.Dehydropeptidase is found in the kidney and is responsible for degrading the antibiotic imipenem. Cilastatin is therefore combined intravenously with imipenem in order to protect it from dehydropeptidase and prolong...

)
meropenem
Meropenem
Meropenem is an ultra-broad spectrum injectable antibiotic used to treat a wide variety of infections, including meningitis and pneumonia. It is a beta-lactam and belongs to the subgroup of carbapenem, similar to imipenem and ertapenem. Meropenem was originally developed by Sumitomo Pharmaceuticals...
ertapenem
Ertapenem
Ertapenem is a carbapenem antibiotic marketed by Merck as Invanz. It is structurally very similar to meropenem in that it possess a 1-β-methyl group.-Indications:...
faropenem
Faropenem
Faropenem is an orally-active beta-lactam antibiotic belonging to the penem group.It is resistant to some forms of extended-spectrum beta-lactamase.It is orally available.-Forms:...
doripenem
Doripenem
Doripenem is an ultra-broad spectrum injectable antibiotic. It is a beta-lactam and belongs to the subgroup of carbapenems. It was launched by Shionogi Co. of Japan under the brand name Finibax in 2005 and is being marketed outside Japan by Johnson & Johnson...

Monobactams

Unlike other β-lactams, the monobactam contains a nucleus with no fused ring attached. Thus, there is less probability of cross-sensitivity reactions.

aztreonam
Aztreonam
Aztreonam is a synthetic monocyclic beta-lactam antibiotic , with the nucleus based on a simpler monobactam isolated from Chromobacterium violaceum. It was approved by the U.S. Food and Drug Administration in 1986...

(Azactam)
tigemonam
Tigemonam
Tigemonam is a monobactam antibiotic....
nocardicin A
Nocardicin A
Nocardicin A is a β-lactam antibiotic included in the monobactam subclass. It is secreted by the bacterium Nocardia uniformis subsp. tsuyamenensis as a metabolic product catalyzed by the enzyme nocardicin-A epimerase....
tabtoxinine-β-lactam

β-lactamase inhibitors

Although they exhibit negligible antimicrobial activity, they contain the β-lactam ring. Their sole purpose is to prevent the inactivation of β-lactam antibiotics by binding the β-lactamases, and, as such, they are co-administered with β-lactam antibiotics.

clavulanic acid
Clavulanic acid
Clavulanic acid is a competitive β-lactamase inhibitor combined with penicillin group antibiotics to overcome certain types of antibiotic resistance. It is used to overcome resistance in bacteria that secrete β-lactamase, which otherwise inactivates most penicillins...
tazobactam
Tazobactam
Tazobactam is a compound that inhibits the action of bacterial beta-lactamases. It is added to the extended spectrum beta-lactam antibiotic piperacillin to produce Tazocin or Zosyn or Piprataz...
sulbactam
Sulbactam
Sulbactam is a molecule that is given in combination with beta-lactam antibiotics to inhibit beta-lactamase, an enzyme produced by bacteria that destroys the antibiotics...