Antimicrobial pharmacodynamics

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Antimicrobial pharmacodynamics is the relationship between the concentration of an antibiotic and its ability to inhibit vital processes of endo- or ectoparasites and microbial organisms. [1] This branch of pharmacodynamics relates the concentration of an anti-infective agent to its effect, specifically to its antimicrobial effect. [2]

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Concentration-dependent effects

The minimum inhibitory concentration (MIC) and minimum bactericidal concentration are used to measure in vitro activity of antimicrobial agents. They are good indicators of antimicrobial potency, but don't give any information relating to time-dependent antimicrobial killing (the so-called post antibiotic effect). [1]

Post-antibiotic effect

The post-antibiotic effect (PAE) is defined as persistent suppression of bacterial growth after a brief exposure (1 or 2 hours) of bacteria to an antibiotic even in the absence of host defense mechanisms. [3] Factors that affect the duration of the post-antibiotic effect include duration of antibiotic exposure, bacterial species, culture medium and class of antibiotic. It has been suggested that an alteration of DNA function is possibly responsible for the post-antibiotic effect following the observation that most inhibitors of protein and nucleic acid synthesis (aminoglycosides, fluoroquinolones, tetracyclines, clindamycin, certain newer macrolides/ketolides, and rifampicin and rifabutin) induce long-term PAE against susceptible bacteria. [3] [4] Theoretically, the ability of an antibiotic to induce a PAE is an attractive property since antibiotic concentrations could fall below the MIC for the bacterium yet retain their effectiveness in their ability to suppress the growth. Therefore, an antibiotic with PAE would require less frequent administration and it could improve patient adherence with regard to pharmacotherapy. [3] [5] Proposed mechanisms include (1) slow recovery after reversible nonlethal damage to cell structures; (2) persistence of the drug at a binding site or within the periplasmic space; and (3) the need to synthesize new enzymes before growth can resume. Most antimicrobials possess significant in vitro PAEs (≥ 1.5 hours) against susceptible gram-positive cocci. Antimicrobials with significant PAEs against susceptible gram-negative bacilli are limited to carbapenems and agents that inhibit protein or DNA synthesis. [6]

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<span class="mw-page-title-main">Antibiotic</span> Antimicrobial substance active against bacteria

An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of such infections. They may either kill or inhibit the growth of bacteria. A limited number of antibiotics also possess antiprotozoal activity. Antibiotics are not effective against viruses such as the common cold or influenza; drugs which inhibit growth of viruses are termed antiviral drugs or antivirals rather than antibiotics. They are also not effective against fungi; drugs which inhibit growth of fungi are called antifungal drugs.

<span class="mw-page-title-main">Bacteriostatic agent</span>

A bacteriostatic agent or bacteriostat, abbreviated Bstatic, is a biological or chemical agent that stops bacteria from reproducing, while not necessarily killing them otherwise. Depending on their application, bacteriostatic antibiotics, disinfectants, antiseptics and preservatives can be distinguished. When bacteriostatic antimicrobials are used, the duration of therapy must be sufficient to allow host defense mechanisms to eradicate the bacteria. Upon removal of the bacteriostat, the bacteria usually start to grow rapidly. This is in contrast to bactericides, which kill bacteria.

<span class="mw-page-title-main">Linezolid</span> Antibiotic medication

Linezolid is an antibiotic used for the treatment of infections caused by Gram-positive bacteria that are resistant to other antibiotics. Linezolid is active against most Gram-positive bacteria that cause disease, including streptococci, vancomycin-resistant enterococci (VRE), and methicillin-resistant Staphylococcus aureus (MRSA). The main uses are infections of the skin and pneumonia although it may be used for a variety of other infections including drug-resistant tuberculosis. It is used either by injection into a vein or by mouth.

<span class="mw-page-title-main">Methicillin</span> Antibiotic medication

Methicillin (USAN), also known as meticillin (INN), is a narrow-spectrum β-lactam antibiotic of the penicillin class.

<span class="mw-page-title-main">Aminoglycoside</span> Antibacterial drug

Aminoglycoside is a medicinal and bacteriologic category of traditional Gram-negative antibacterial medications that inhibit protein synthesis and contain as a portion of the molecule an amino-modified glycoside (sugar). The term can also refer more generally to any organic molecule that contains amino sugar substructures. Aminoglycoside antibiotics display bactericidal activity against Gram-negative aerobes and some anaerobic bacilli where resistance has not yet arisen but generally not against Gram-positive and anaerobic Gram-negative bacteria.

<span class="mw-page-title-main">Nalidixic acid</span> First of the synthetic quinolone antibiotics

Nalidixic acid is the first of the synthetic quinolone antibiotics.

<span class="mw-page-title-main">Piperacillin</span> Chemical compound

Piperacillin is a broad-spectrum β-lactam antibiotic of the ureidopenicillin class. The chemical structure of piperacillin and other ureidopenicillins incorporates a polar side chain that enhances penetration into Gram-negative bacteria and reduces susceptibility to cleavage by Gram-negative beta lactamase enzymes. These properties confer activity against the important hospital pathogen Pseudomonas aeruginosa. Thus piperacillin is sometimes referred to as an "anti-pseudomonal penicillin".

<span class="mw-page-title-main">Tigecycline</span> Chemical compound

Tigecycline, sold under the brand name Tygacil, is an tetracycline antibiotic medication for a number of bacterial infections. It is a glycylcycline administered intravenously. It was developed in response to the growing rate of antibiotic resistant bacteria such as Staphylococcus aureus, Acinetobacter baumannii, and E. coli. As a tetracycline derivative antibiotic, its structural modifications has expanded its therapeutic activity to include Gram-positive and Gram-negative organisms, including those of multi-drug resistance.

<span class="mw-page-title-main">Antibiotic sensitivity testing</span> Microbiology test used in medicine

Antibiotic sensitivity testing or antibiotic susceptibility testing is the measurement of the susceptibility of bacteria to antibiotics. It is used because bacteria may have resistance to some antibiotics. Sensitivity testing results can allow a clinician to change the choice of antibiotics from empiric therapy, which is when an antibiotic is selected based on clinical suspicion about the site of an infection and common causative bacteria, to directed therapy, in which the choice of antibiotic is based on knowledge of the organism and its sensitivities.

Ampicillin/sulbactam is a fixed-dose combination medication of the common penicillin-derived antibiotic ampicillin and sulbactam, an inhibitor of bacterial beta-lactamase. Two different forms of the drug exist. The first, developed in 1987 and marketed in the United States under the brand name Unasyn, generic only outside the United States, is an intravenous antibiotic. The second, an oral form called sultamicillin, is marketed under the brand name Ampictam outside the United States, and generic only in the United States. Ampicillin/sulbactam is used to treat infections caused by bacteria resistant to beta-lactam antibiotics. Sulbactam blocks the enzyme which breaks down ampicillin and thereby allows ampicillin to attack and kill the bacteria.

<span class="mw-page-title-main">Tetracycline antibiotics</span> Type of broad-spectrum antibiotic

Tetracyclines are a group of broad-spectrum antibiotic compounds that have a common basic structure and are either isolated directly from several species of Streptomyces bacteria or produced semi-synthetically from those isolated compounds. Tetracycline molecules comprise a linear fused tetracyclic nucleus to which a variety of functional groups are attached. Tetracyclines are named after their four ("tetra-") hydrocarbon rings ("-cycl-") derivation ("-ine"). They are defined as a subclass of polyketides, having an octahydrotetracene-2-carboxamide skeleton and are known as derivatives of polycyclic naphthacene carboxamide. While all tetracyclines have a common structure, they differ from each other by the presence of chloride, methyl, and hydroxyl groups. These modifications do not change their broad antibacterial activity, but do affect pharmacological properties such as half-life and binding to proteins in serum.

<span class="mw-page-title-main">Filamentation</span>

Filamentation is the anomalous growth of certain bacteria, such as Escherichia coli, in which cells continue to elongate but do not divide. The cells that result from elongation without division have multiple chromosomal copies.

<span class="mw-page-title-main">Marbofloxacin</span> Chemical compound

Marbofloxacin is a carboxylic acid derivative third generation fluoroquinolone antibiotic. It is used in veterinary medicine under the brand names Marbocyl, Forcyl, Marbo vet and Zeniquin. A formulation of marbofloxacin combined with clotrimazole and dexamethasone is available under the name Aurizon.

In microbiology, the minimum inhibitory concentration (MIC) is the lowest concentration of a chemical, usually a drug, which prevents visible in vitro growth of bacteria or fungi. MIC testing is performed in both diagnostic and drug discovery laboratories.

<span class="mw-page-title-main">Oritavancin</span> Pharmaceutical drug

Oritavancin, sold under the brand name Orbactiv among others, is a semisynthetic glycopeptide antibiotic medication for the treatment of serious Gram-positive bacterial infections. Its chemical structure as a lipoglycopeptide is similar to vancomycin.

<span class="mw-page-title-main">Cefoxitin</span> Chemical compound

Cefoxitin is a second-generation cephamycin antibiotic developed by Merck & Co., Inc. from Cephamycin C in the year following its discovery, 1972. It was synthesized in order to create an antibiotic with a broader spectrum. It is often grouped with the second-generation cephalosporins. Cefoxitin requires a prescription and as of 2010 is sold under the brand name Mefoxin by Bioniche Pharma, LLC. The generic version of cefoxitin is known as cefoxitin sodium.

<span class="mw-page-title-main">Arbekacin</span> Antibiotic

Arbekacin (INN) is a semisynthetic aminoglycoside antibiotic which was derived from kanamycin. It is primarily used for the treatment of infections caused by multi-resistant bacteria including methicillin-resistant Staphylococcus aureus (MRSA). Arbekacin was originally synthesized from dibekacin in 1973 by Hamao Umezawa and collaborators. It has been registered and marketed in Japan since 1990 under the trade name Habekacin. Arbekacin is no longer covered by patent and generic versions of the drug are also available under such trade names as Decontasin and Blubatosine.

Bacterial morphological plasticity refers to changes in the shape and size that bacterial cells undergo when they encounter stressful environments. Although bacteria have evolved complex molecular strategies to maintain their shape, many are able to alter their shape as a survival strategy in response to protist predators, antibiotics, the immune response, and other threats.

The Eagle effect, Eagle phenomenon, or paradoxical zone phenomenon, named after Harry Eagle who first described it, originally referred to the paradoxically reduced antibacterial effect of penicillin at high doses, though recent usage generally refers to the relative lack of efficacy of beta lactam antibacterial drugs on infections having large numbers of bacteria. The former effect is paradoxical because the effectiveness of an antibiotic generally rises with increasing drug concentration.

<span class="mw-page-title-main">Ceftolozane/tazobactam</span> Antibiotic

Ceftolozane/tazobactam, sold under the brand name Zerbaxa, is a combination antibiotic medication used for the treatment of complicated urinary tract infections and complicated intra-abdominal infections in adults. Ceftolozane is a cephalosporin antibiotic, developed for the treatment of infections with gram-negative bacteria that are resistant to conventional antibiotics. It was studied for urinary tract infections, intra-abdominal infections and ventilator-associated bacterial pneumonia.

References

  1. 1 2 C.H. Nightingale, T. Murakawa, P.G. Ambrose (2002) Antimicrobial Pharmacodynamics in Theory and Clinical Practice Informa Health Care ISBN   0-8247-0561-0
  2. Drusano GL (2004). "Antimicrobial pharmacodynamics: critical interactions of 'bug and drug'". Nat. Rev. Microbiol. 2 (4): 289–300. doi:10.1038/nrmicro862. PMID   15031728. S2CID   23843703.
  3. 1 2 3 "Archived copy" (PDF). Archived from the original (PDF) on 2015-07-13. Retrieved 2008-11-13.{{cite web}}: CS1 maint: archived copy as title (link)
  4. Guan L, Blumenthal RM, Burnham JC (October 1992). "Analysis of macromolecular biosynthesis to define the quinolone-induced postantibiotic effect in Escherichia coli". Antimicrob. Agents Chemother. 36 (10): 2118–24. doi:10.1128/aac.36.10.2118. PMC   245465 . PMID   1280055.
  5. Zarrini G, Bahari-Delgosha Z, Mollazadeh-Moghaddam K, Shahverdi AR (2010). "Post-antibacterial effect of thymol". Pharmaceutical Biology. 48 (6): 633–636. doi: 10.3109/13880200903229098 . PMID   20645735. S2CID   39240936.
  6. Katzung basic and clinical pharmacology 13th edition 2015