STERILIZATION METHODS
STERILIZATION
is the process of destroying all forms of microbial life. A sterile object in the microbiological sense, free from living microorganisms. SANITATION
consists of reducing the microbial population to harmless levels through an agent, according to the requirements of public health, is usually a chemical agent that kills 99.9% bacteria growth.
DESINFECCCION
Destruction of potentially pathogenic microorganisms such as bacteria, fungi and protozoa. Disinfection can be accomplished by wet or dry heat, radiation, and autoclave (moist heat under pressure) or chemical treatment. Chlorination is a major disinfection procedure in water purification. SANITATION
is a concentrated disinfectant based on quaternary ammonium complex generation, control and eliminate pathogens. Has high effectiveness in controlling microorganisms associated with diseases of high incidence, such as bacteria, Staphylococcus aureus, E coli, Salmonella typhi, Klebsiella pneumoniae.
PHYSICAL AGENTS OF WET HEAT STERILIZATION
So Moist heat inactivation requires lower temperatures than is done in the absence of water. Some examples of conditions of wet heat inactivation: Microbe
conditions
Most vegetative cells of bacteria, yeasts and fungi 80 o C, 5-10 min 58oC
tubercle bacillus, Mycobacterium tuberculosis 30 min
59oC, 20 min
tubercle bacillus 65oC, 2 min
Staphylococcus aureus, Enterococcus faecalis 60 C, 60 min
Most pathogenic bacteria spores 100oC, few min
pathogen Clostridium botulinum spores 100oC, 5.5 hours
Clostridium and Bacillus spores 100oC saprophytes, many hours
Clostridium and Bacillus spores of saprophytes 120oC, 15 minutes
methods main achieved by heat sterilization of wet: Autoclave
Introduced by Chamberland in 1884. Is a device that allows warm moist heat samples to temperatures above the boiling point of water (not boiling it), because the treatment is carried out in a sealed chamber saturated with water vapor at pressures above atmospheric. Sterilization parameters usually are: temperature 121 ° C and 10-15 min. As you might guess, these parameters are set by the resistance of spores of species that are more life forms that endure the heat without losing viability.
quick action of moist heat is largely dependent on the high value of latent heat of water (540 cal • g-1), this means that colder objects to warm up quickly by condensation of water on its surface. Tindalización
name in honor of John Tyndall is a fractional sterilization method for materials that are inactivated or damaged more than 100 º C. Involves subjecting the material to several cycles (usually 3 or 4) successive phases each:
a) In the first phase the material is heated to a temperature between 50 and 100 ° C for 1 to 2 hours;
b) the second phase the material is incubated in an oven at 30-37 º C for 24 hours.
During phases of type a) killed all vegetative cells of the sample, but remain viable spores, which are activated to germinate. During phases of type b) produce germination of spores activated in the respective preceding stage. In the next phase of type a) vegetative cells die from germination in the previous phase, and so on, until after a few cycles there is no microorganisms in the sample.
Main applications of moist heat:
1. In the daily practice of the microbiology laboratory in the sterilization of culture media and solutions.
2. In the sterilization of surgical material.
3. In partial sterilization or inactivation, in the food (canned food, milk and dairy products).
a) In the dairy industry use as methods of sterilization uperización call. The uperización or UHT treatment is a moist heat treatment where high temperatures are used for a few seconds (eg.: 135-150 ° C for 1-2 sec.)
b) It is not always necessary to sterilize the milk, but may be sufficient to eliminate potential pathogens that can contaminate it, and are more sensitive to heat than harmless saprophytes. This partial inactivation of the microbial population of the milk we will keep it for a few days, just alter organoleptic and nutritional qualities. Here are the most common procedures to achieve this:
i. Pasteurization (in honor of Pasteur, which was introduced in the early 1860) is to treat the milk to 63oC for 30 min, after which it is cooled and packed quickly.
ii. The flash pasteurization (also known by its initials in English HTST of high temperature-short time) is accomplished by heating at 72 ° C for 15 seconds, after which the sample is cooled quickly. This technique is currently the most widely used because:
kills faster;
better kill resistant organisms;
least altered taste;
operates in continuous flow (and can process large volumes of milk).
After pasteurization, the number of viable bacteria dropped by 97-99%. Potential pathogens that can bring the milk (Brucella, Salmonella, Mycobacterium tuberculosis, Streptococcus, etc.) are easily removed. Pasteurization is also used for the preparation of vaccines based on inactivated microorganisms by heat. DRY HEAT
dry heat sterilization at higher temperatures need to resort to the made by the wet heat, because there is no water, breakage of hydrogen bonds and denaturation of proteins and membrane fusion is carried out at higher energies. Other effects of dry heat are the oxidative damage and lead to increased concentration of electrolytes. Application of dry heat
:
1. The so-called Pasteur oven by heating at 160-170 ° C for 2-3 hours can sterilize laboratory inert heat resistant material: glass and metal, oils and jellies, etc.
2. Flamed to the flame (to red) seed metal handles, which are inoculated with bacteria.
3. Incineration of waste materials. BOILING
or objects contaminated materials exposed to boiling can not be sterilized effectively. It is true that all vegetative cells destroyed in minutes when exposed to boiling, but some bacterial spores resist boiling for several hours. With the present instrumental practice for short periods to get more than boiling water disinfection sterilization, for that reason can not be used in the laboratory and sterilization method. INCINERATION
Mata microorganisms, this method is used to destroy skeletons, animals infected laboratory waste and other infected materials. The destruction of microorganisms by incineration also performed routinely in laboratories when introduced into the flame of a Bunsen burner handle plantings but Be careful not to produce sparks otherwise be scattered droplets carrying viable organisms, the sputtering is reduced or eliminated by drying the crops handle calls outside before putting it in this. FILTRATION
Some materials, particularly biological fluids such as serum of animals or solutions of substances such as enzymes and some vitamins or antibiotics, are thermolabile, is destroyed by heat. Also other physical agents such as radiation are harmful to these materials and impractical to sterilize them, therefore have the option to do so by filtration.
BACTERIOLOGICAL FILTERS For many years a variety of bacterial filters have been available to microbiologists. These filters are made of different materials: plates Seitz asbestos filters, diatomaceous earth in the Berkefeld, the Chamberland porcelain - Pasteur, glass fiber discs in other filters.
pore diameters bacteriological filters measured from about 1 micron to several. Almost all the filters are based on the average of opening your pores, porosity alone is not the only factor that prevents the passage of microorganisms. Other factors such as the electric charge of the filter, the electrical load of microorganisms and the nature of the liquid to be filtered, are related to the effectiveness of filtration.
In recent years we have developed a new type of filter (membrane or molecular) in which the pores are of uniform size and specific and determined. The membrane filters are composed of molecular or biological inert cellulose esters. Circular membranes are prepared as approximately 150 microns thick and contain millions of microscopic pores of very uniform diameter. Filters of this type can produce porosity ranging from about 0.01 to 10 microns. Have also been adapted to microbiological processes to identify and enumerate microorganisms in water samples and other materials.
filters Developing high-efficiency particulate air (HEPA) has made it possible to obtain clean air indoors or quarters. This type of filtration and laminar flow system, are widely used for outdoor dust and bacteria.
EFFECT OF RADIATION ON BACTERIA
GENERAL CONCEPTS ON RADIATION AND BIOMOLECULES
radiation can be defined as the propagation of energy through space. The main types of radiation can have effects on living things are: l
electromagnetic radiation (wavelengths in nm)
infrared (IR) light radiation
800-106 380-800
ultraviolet (UV) rays from 13.6 to 380
0.14-13.6 X-ray cosmic rays
0.001 to 0.14 g
The effects of radiation absorption depends on: < 0.001
the radiation energy absorbed;
The nature of the material.
1) If the energy is E> 10 eV, we speak of ionizing radiation: are the X-rays and g rays (the latter are issued as a result of the disintegration of radioisotopes). A high-energy photon strikes an atom, causing the expulsion of a high-energy electron (photoelectron), and leaving the atom ionized (positively charged). The electron usually expelled enough energy to cause a new ionization, which comes another high-energy electron, etc.. ionizations produced a string with linear energy transfer, until it is dissipated in the material: the last electron in the chain is captured by another atom or molecule, which is negatively charged. The end result is that form ion pairs (one positive and one negative). In turn, these ions originated electronic rearrangements tend to experience further, that give rise to chemical changes in the system that had undergone irradiation.
2) If the energy is E
Fluorescence: emission energy at a longer wavelength than the incident photon; <10 eV, no se producen ionizaciones: los electrones del átomo o molécula pasan transitoriamente (de 10-8 a 10-10 segundos) a un nivel energético superior (entonces se habla de que el átomo o molécula están excitados), pero enseguida dicho electrón vuelve al estado energético inicial. En su regreso a su nivel energético previo, el electrón puede dar origen a una variedad de fenómenos:
Photosensitization: energy is transferred to another molecule,
photochemical reactions: it creates a chemical change;
emission of heat energy simply dissipates in collisions between molecules.
visible and UV light can lead to photochemical reactions, apart from heat. But the only infrared radiation leads to heat dissipation, while certain anoxygenic photosynthetic bacteria can take advantage of the infrared for photosynthesis.
EFFECTS OF RADIATION AND ITS APPLICATIONS
Although the radiation unit emitted is the roentgen (R), biological effects parameters are used to measure the energy absorbed by the system: the units are the rad (100 erg / g) and gigaray (1Gy = 100 rads).
In general, microorganisms are more resistant to ionizing radiation that superior beings. For example, the decimal reduction dose (D10) for the endospores of certain species of Clostridium is of 2000-3000 Gy. Vegetative cells of the bacterium Deinococcus radiodurans is 2,200 Gy. Other more "normal" have a decimal reduction doses around 200-600 Gy.
ionizing radiation sources are X-ray machines, g rays radioisotopes, such as Co60 or Cs137.
The effects of ionizing radiation are lethal, both direct and indirect, as well as mutagenic. Direct lethal effects are achieved with high doses of radiation, while the indirect lethal and mutagenic effects are achieved at lower doses.
1. Direct lethal effect: on the impact of those of ionizing radiation on a molecule essential for life, which is DNA (as obviously it is absolutely essential and provides a single copy of most bacterial genes). DNA damage are principally breaks in both strands, and cross-linking between these chains, which can not be repaired.
2. Mutagenic effect, derived from the production minor damage to DNA can be repaired by error-prone mechanisms.
3. Indirect lethal effect: This type of effect is most important, and derives from the radiolysis of water, which generates nascent hydrogen (H •) and hydroxyl radical (OH •). The hydroxyl radical reacts readily with macromolecules, especially DNA, causing breaks in both strands, which results in lethal effects. If, in addition, the bacterium is exposed to oxygen while it is radiating, the effect is even stronger, because the O2 reacts with free radicals, causing chain reactions of auto-oxidation, very destructive, and promoting training peroxides and epoxides also lethal.
H • + O2 à • 2 •
HO2 HO2 H2O2 + O2 à
The main applications of ionizing radiation are sterilization: Material
pharmaceuticals (antibiotics, hormones, etc.);
medical and surgical equipment (gloves surgeon, nylon sutures, syringes, needles, scalpels, catheters, prostheses, etc.);
Packaged Foods (although some countries still open debate by certain groups about the safety of this treatment.)
EFFECTS OF UV RADIATION
UV radiation has Lethal and mutagenic effect, which depends on its wavelength. This is due to selective absorption of wavelengths of certain biological molecules:
Proteins have two peaks (ie maximum) absorption: one at 280 nm due to aromatic amino acids (Trp, Tyr, Phe ) and another at 230 nm, due to the peptide.
DNA and RNA absorb at 260 nm, due to the double bond between positions 4 and 5 of the purine and pyrimidine bases.
UV rays are not active ionizing radiation, but also cause chemical changes in the absorbing molecules, so called generically altered molecules appear photoproducts. Photoproducts originate inactivation of macromolecules, although, as we shall see, the DNA has mechanisms to mitigate or eliminate these potentially damaging changes.
The consequences of inactivating proteins or RNA are felt no lethal effects, as there are many copies of each of these types of macromolecules, and can be re-synthesized. In contrast, inactivation of the single chromosome of the bacterium is lethal mutagenic primary and secondary. Therefore, the spectrum of biological action of UV light equivalent to UV absorption by DNA (260 nm).
CONTROL CHEMICALS.
Factors should be considered in the selection of antimicrobial chemicals are
1. Nature of the material to be treated.
2. Types of microorganisms.
3. Environmental conditions.
MAIN GROUPS OF CHEMICAL AGENTS ANTIMICROBIAL
phenol has the double distinction of having been used by Lister in the 1860 in its work to develop aseptic surgical techniques and to be the standard for comparison with other disinfectants to test their bacteria. Denaturing
first cell proteins and cell membranes after damage.
phenolic compounds are bactericidal or bacteriostatic depending on the concentration at which they are used. Bacterial spores and viruses are more resistant than vegetative cells. Some phenolic compounds are highly fungicides. The activity of these compounds is reduced at alkaline pH and organic material. It also decreases the antimicrobial activity at low temperature and in the presence of soap.
ALCOHOLS
ethyl alcohol concentrations between 50% and 70% is effective against vegetative cells and spores do not produce, 70% is the most effective bacterial concentration.
concentrations acting against the vegetative cells are largely ineffective against spores bacteria.
The methyl alcohol is less bactericidal than ethyl alcohol and is also highly toxic and is not used in general for her destruction of microorganisms. The higher alcohols (propyl, butyl, amyl and others) are more germicidal than ethyl is an increase in germicidal power is increased as molecular weight alcohols.
The propyl alcohol, isopropyl alcohol in concentrations between 40% and 80% have been reported as useful for disinfecting the skin.
The effectiveness of alcohol for disinfection of surfaces should be attributed to its action cleanser or detergent.
Alcohol reduces the microbial flora of the skin and serves to disinfect oral clinical thermometers.
alcohol concentrations above 60% are effective against the virus, this action is influenced considerably by the amount of foreign protein material in the mix. Foreign proteins react with the alcohol and so the virus is protected. HALOGEN
IODINE
is one of the oldest and biocides effective. Recognized by the United States Pharmacopoeia in 1830, the pure iodine is a dark blue crystal element with a metallic sheen. Is not very soluble in water but much alcohol and aqueous solutions of sodium or potassium iodide.
This item is traditionally used as a germicidal agent in the form known como tintura de yodo. El yodo también se usa en las formas conocidas como yodoforas.
Uno de los agentes es la polivinilpirrolidona (PVP); el complejo se expresa PVP-I, el yodo se libera lentamente de este compuesto. Las sustancias yodoforas poseen las características germicidas del yodo y las ventajas adicionales de producir muy poca irritación y no teñir.
El yodo es un agente bactericida muy eficaz y el único que tiene efectos contra toda clase de bacterias, también tiene propiedades esporocidas.
Posee propiedades funguicidas y antivirales importantes, las soluciones de yodo se usan principalmente para desinfectar la piel. También sirve para otros propósitos, como la desinfección del agua, aire (vapores iodine) and sanitation of utensils used in food.
Iodine is an oxidizing agent and this partly accounts for their antimicrobial activity.
CHLORINE Chlorine, hypochlorites and chloramines are disinfectants that act on proteins and nucleic acids of microorganisms. Oxidize-SH groups and amino groups attack, hidroxifenol indoles and tyrosine.
The product most commonly used chlorine disinfection is sodium hypochlorite (bleach water), which is active against all bacteria, including spores, and is also effective in a wide range of temperatures.
bactericidal activity of sodium hypochlorite is due to hypochlorous acid (HClO) and Cl2 is formed when hypochlorite is diluted in water. The germicidal activity of hypochlorous ion is very limited due to its charge can not easily penetrate the cell through the membrane citoplamática. In contrast, hypochlorous acid is neutral and easily penetrates the cell, while the gas enters as Cl2.
sodium hypochlorite is sold in concentrated solutions (50-100 g / l active chlorine) at alkaline pH in dark containers that promote stability, but is inactive as a disinfectant. Because of this, is to be used dilute solutions in water (which has a slightly acidic pH) in order to obtain hypochlorous acid. Generally, solutions are used with a concentration of 0.1-0.5% active chlorine.
Its activity is influenced by the presence of organic matter, as there may be substances in the environment can react with chlorinated compounds that reduce their effective concentration. Mercurial compounds
These types of compounds combine with SH groups of proteins, inactivating enzymes. Within the organic mercurial are the metaphase and the Merthiolate.
HYDROGEN PEROXIDE
is a weak antiseptic, capable of oxidizing and forming free radicals.
Currently, the gaseous hydrogen peroxide is being used as a surface disinfectant and decontaminate biological cabinets because it lacks the toxic and carcinogenic properties of ethylene oxide and formaldehyde. COLORANTS
interfere in the synthesis of nucleic acids and proteins (acridine) or interfere with cell wall synthesis (derived from triphenylmethane). Acridine is inserted between two successive bases of DNA separating them physically. This causes errors in DNA duplication. Triphenylmethane derivatives (gentian violet, malachite green and bright green) block the conversion of UDP-acetylmuramic acid to UDP-Acetylmuramyl-peptide.
R = HSO4-
Brilliant Green R = Cl-Malachite Green
Gentian Violet
alkylating agents are sterilizing agents, active on both vegetative cells and on spores, which exert their lethal effect by alkylating action of proteins and nucleic acids.
Formaldehyde (HCHO). The annihilation occurs
replacing the labile hydrogens of certain chemical groups (-NH2,-OH,-COOH and-SH), producing:
hydroxymethyl
Condensation (crossovers). Commercial uses
:
As a gas, in the clean room;
As formalin (solution 35% aqueous);
As paraformaldehyde (polymer solid 91-99% purity).
Formalin is used to preserve tissue, embalming fluids, and 0.2-0.4% in the preparation of vaccines.
glutaraldehyde.
is less toxic and more potent than formaldehyde and is not affected by proteínas.Cada materials increasingly being used as a cold sterilizing surgical instruments. It is only recommended for sterilization of respiratory therapy equipment.
ethylene oxide.
has an effect similar to that of formaldehyde, substitutions and irreversible crosslinks amino groups, sulfhydryl, ETC. protein. It also reacts with phosphate and nitrogen rings of nucleic acids.
is an agent used as a sterilant gas, but is slow acting. Used when you can not use heat sterilization: sterilization of plastic materials, drugs, certain biological products, electronic equipment. The operation is similar to the autoclave chambers. However, it is an expensive and exhibits a number of risks: present action, blistering toxicity to humans (mutagenic and carcinogenic).
propionyl-ß-lactone.
is 25 times more active than formaldehyde. Acts as a gas in the presence of 80-90% relative humidity, although it is slightly pungent.
quaternary ammonium salts (cationic detergent)
detergents are more powerful in terms of disinfectant activity, being active against Gram-positive and Gram-negative. The main ones are called quaternary ammonium compounds:
quaternary ammonium salts, especially those who go as chlorides or bromides. Its general formula can be represented as follows:
The four substituents (R1 to R4) of N are varied hydrocarbon chains. Quaternary ammonium salts most active are those that have three short alkyl groups and alkyl group length: cetylpyridinium chloride, benzalkonium chloride
Mechanism of action: The hydrophobic portion penetrates the membrane, while the polar cationic group associated with the phosphates of phospholipids, causing changes in these membranes, as reflected in the loss of their semi-permeability, with output of metabolites N and P from the cytosol. It is then that the detergent can enter the cell interior, with a side effect of protein denaturation. Its activity is enhanced at alkaline pH.
are rapidly bactericidal at low concentrations (about one part per million, 1 ppm), provided that the material to be treated there is no organic matter.
uses, advantages and disadvantages: They have low toxicity, which can be used as disinfectants and antiseptics to the skin. Are also used to disinfect equipment industries alimentarias.Su activity is neutralized by soaps and phospholipids, precipitating in his presence. ANTIBIOTICS
The term antibiotic was proposed by Selman A. Waksman, discoverer of streptomycin, to identify substances with antimicrobial activity and structures learned from living organisms.
The previous record search shows that in 1889 Jean Paul Vuillemin in a paper entitled "Symbiose et antibiose" antibiosis created the term to describe the struggle between living things for survival. Later, Ward takes this word to describe the microbial antagonism. Later, already in full antibiotic era, the term meant, for some time, a substance extracted from living things, and they be bacteria, fungi, algae, able to override the life of microorganisms.
The antibiotic is a living world. But the advance of technology, the growing knowledge of the formulas of various antibiotics, the possibility of preparing synthetic chemical bases blurred based on the value of their origin.
ACTION OF ANTIBIOTICS Antibiotics can be bacteriostatic (stopping the growth and multiplication cell) or bactericidal (causing death of bacteria). To perform these functions, antibiotics should get in contact with the bacteria.
is believed that antibiotics interfere with bacterial cell surface, causing a change in their ability to reproduce. The proof of the action of an antibiotic in the lab shows how much exposure to the drug is needed to stop the reproduction or to kill bacteria. Although a large amount of an antibiotic would take less time to kill bacteria that cause disease, such doses commonly would make the person suffering from a disease caused by the drug. Therefore, antibiotics are given in a series of small amounts. This ensures that the bacteria are killed or reduced to a sufficient number so that the body can repel. When you take an insufficient amount of antibiotic, bacteria can often develop methods to protect themselves against this antibiotic. So the next time you use the antibiotic against the bacteria will not be effective. ADMINISTRATION OF ANTIBIOTICS
To act against infectious organisms, an antibiotic can be applied externally, as in the case of a cut on the skin surface, or internally, reaching the bloodstream into the body. Antibiotics are produced in various ways and in different ways.
forms of antibiotics are: Local
Topical application means "local area" as the skin, eyes, or mucous membrane. Antibiotics for local use are available as powders, ointments or creams. Oral
There are two forms of action for oral application.
• The tablets, liquids, and capsules that are swallowed. In this case the antibiotic is released in the small intestine to be absorbed into the bloodstream.
• Candy or pills, which dissolve in the mouth, where the antibiotic is absorbed through the membrane mucosa. Parenteral
.
applications outside the intestine are called parenteral. An application form is injected, which can be subcutaneous (under the skin), intramuscular (into a muscle) or intravenously (into a vein). Parenteral administration of an antibiotic is used when a physician requires a strong and rapid concentration of the antibiotic in the bloodstream. Natural
Manufacturing.
time to all antibiotics were made from living organisms. This process, known as biosynthesis, is still used in the manufacture of some antibiotics. Organisms are actually those that manufacture the antibiotic. People involved merely provides favorable conditions for agencies to do their job and then extract the drug.
Currently most natural antibiotics are produced by fermentation stages. In this method, strains are grown in high yields under optimal conditions and microorganisms in a nutrient medium within the fermentation tanks of several thousand Liíto capacity. This is a stock that is maintained at a temperature of 25 C (77 F) and is shaken by more than 100 hours. Then the strains are removed from the fermentation broth and the antibiotic is then removed from the broth by filtration, precipitation or any other method Synthetic
separation.
All types of penicillin have an identical chemical called core ring. The chemical chain that is attached to the ring is different in each type. Changing the chain molecules, scientists design drugs with potentially different effects on different organisms. Some of these drugs are useful for treating infections, some are not.
Pharmaceutical manufacturers are now using computer-generated images of the rings and experiment with an endless variety of possible strings. The researchers have developed antibiotics with long half-life (the period of effectiveness), which allows one to take medication time in 24 hours instead of every few hours. The newer antibiotics are also more effective against a wider range of infections than they were earlier drugs.
bacterial spectrum.
The action of an antibiotic is measured in terms of bacterial spectrum. It is noted that some antibiotics such as penicillin operate in a restricted area: Gram-negative and gram positive and gram-positive spirochetes. For this reason it is called limited spectrum. Other antibiotics such as tetracycline and chloramphenicol do in many sectors and so they were awarded the name of spectrum. Other antibiotics act on a very limited fraction, eg nistanina on candida albicans. This type of antibiotic spectrum is called selective.
Antibiogram.
The antibiogram is a test of resistance or susceptibility of bacteria under the action of various antibiotics. If an organism is in contact with the drug and still remains vital capacity, follows the failure of the drug product for the germ. There is resistance to the antibiotic. Conversely if the area surrounding the antibiotic is completely free, ie there is no development of the bacterium that is sensitive to the drug.
The area surrounding the antibiotic, called a halo of inhibition, is of great clinical value to start, continue or change therapy.
Technique: The worker will commonly performed diffusion technique in petri dish, because it is easier and less expensive than the tube dilution technique.
This method was first described by Vincent and Vincent in 1944 and partially modified by other researchers. To the culture medium for bacteria placed in petri dishes, he added disks or tablets of antibiotics, conveniently spaced, incubated for 12 hours to 18 hours at 37 º C, after which is read.
antibiogram techniques require lab experience and knowledge appropriate bacteriological, otherwise mistakes are important clinical consequences.
factors to consider that could cause problems at the time of therapy.
1. Medium consistency;
2. Amount of antibiotic contained in each disc tested;
3. Fresh infective material;
4. Incubation time and expected to read out;
5. Correct measurement (in millimeters) of the inhibitory halo;
6. Quality of inhibition;
7. Provide pollution (possible) use of techniques antibiogram defective. Variety
There are dozens of antibiotics. The following are common: The
Penicillins various types of penicillins are a major group of antibacterial antibiotics of which derives from the benzyl penicillin are the only ones from naturally occurring strains. Penicillin G and ampicillin are in this class. Another penicillin, piperacillin called, has proved effective against 92 percent of infections without causing serious side effects. Penicillins are often given in combination with some other drugs in the following categories. Cephalosporins
Similar to penicillins, cephalosporins are often used as a sensitivity (allergic reaction) to penicillin is known or is suspected in a patient. Ceftriaxone sodium is a type of cephalosporin that is effective against deep infections such as those found in the bones and as a result of surgery.
Aminoglycosides Aminoglycosides include streptomycin and neomycin. These drugs are used to treat tuberculosis, bubonic plague and other infections. Because of the potentially serious side effects it generates, such as interference to hearing and sensitivity to sunlight, these drugs are administered with care. (All antibiotics were administered with care, special care is taken about the possible negative consequences than the usual administration of a drug.)
Tetracyclines Tetracyclines are
effective against pneumonia, typhoid, and other bacteria that cause disease but can damage the liver and kidney function. Tetracycline in a special base gel is used to treat many eye infections. Macrolides
The macrolides are frequently used in patients who happen to be sensitive to penicillin. Erythromycin is the best medicine known in this group. Polypeptides
The class of antibiotics called polypeptides is quite toxic (poisonous) and is used mostly on the surface of the skin (topically). Bacitracin is in this category. Drug Sulfo
The sulphonamide was the first antimicrobial drug was used. Sulfa drugs were made from chemicals, have largely the same effects as later developed penicillin. Although sulfa drugs may have harmful effects on the kidneys at the same time are effective against kidney infections are always made it with plenty of water to prevent crystals from forming drugs. Gantrisin is still the most useful among these sulfa drugs.
Other Antimicrobial
Other antimicrobials include furazolidone and tritethoprim. The former is used primarily in gastrointestinal infections, the later, when combined with one of the sulfonamides, is effective in urinary and respiratory infections antifungal
The antifungal fight disease caused by fungi such as candida. The fungus that causes the infection requires long-term. Drugs such as griseofulvin have often been taken for six months. Most funginales infection occur on the skin or mucous membrane. Antiviral
Very few know about virused treat infections (common cold is an example). A virus is thought to be the smallest infectious agent with the ability to replicate (reproduce) itself. It also has baskets of mutant, or change rapidly. The few drugs that are effective against infections virused meddle with the formation of new, normal cells and therefore used with extreme care. Other microbial drugs have little effect on a virus and are given only to treat bacterial infections that accompany or result from primary viral infection. Resistance and Support
Effects
An antibiotic acts by limiting or stand (and thus killing) the growth of a microorganism. Probably does this to meddle with the cell wall of bacteria that is targeted while at the same time have little effect on normal cells of the body.
When one is continually exposed to the antibiotic for an illness of long duration (such as rheumatic fever), the targeted bacteria can develop their own defense drugs. An enzyme that can destroy the drug can be produced by bacteria, or the cell can become resistant to being broken by the action of the antibiotic. When this happens, and often do most with long or frequent treatment with penicillin or streptomycin, the patient is said to be "fast" against drugs. For example, one may be quick to penicillin, meaning that penicillin is not able to help fight infection and should be another type of antibiotic.
allergic reactions to antibiotics are commonly seen as rashes on the skin, but severe anemia (too few red blood cells), disorder stomach, and occasionally may be deafness. once thought that allergic reactions to penicillin antibiotics in particular were frequent and permanent. Recent studies suggest, however, that many people never outgrow their sensitivity or were allergic. The large number of antibiotics that are now available offers a choice of treatment that can, in most instances, prevent allergies caused by drugs.
Okay remember that all drugs can cause undesirable ones, and both effects on the body. Contra-called undesirables, and these must be balanced with the desired effects in determining whether a particular drug does more damage its good effects. It is a fact that all drugs have the potential to be both beneficial and harmful.
Mitosis Mitosis is the process of formation of two identical cells (usually) for replication and division of chromosomes from the original resulting in a "copy" of it.