Microbial control of postharvest diseases has been one of the most extensively studied alternatives and appears to be a viable technology

Control of microbial growth can be by inhibition of growth, killing the microorganisms or removing them from an environment. Antimicrobial agents can be divided into agents that kill microorganisms (bactericidal) and agents that inhibit growth (bacteriostatic) of the microbes .

Electromagnetic irradiation is another effective way to sterilize or reduce microbial burden of almost any substance. Microwaves, ultraviolet (UV) radiation, X-rays, gamma rays and electrons are used although each type of irradiation has a specific mechanism.

Control of microbes is important in the food industry because some microbes spoil food or their growth in food produces toxins. The susceptibility of a product to food spoilage is a consequence of its suitability as a growth medium. Therefore, foods with low water activity are less susceptible to microbial spoilage.

Antibiotics are among the most frequently prescribed medications in modern medicine. Antibiotics cure disease by killing or injuring bacteria. The first antibiotic was penicillin, discovered accidentally from a mold culture. Today, over 100 different antibiotics are available to doctors to cure minor discomforts as well as life-threatening infections. Although antibiotics are useful in a wide variety of infections, it is important to realize that antibiotics only treat bacterial infections. Antibiotics are useless against viral infections (for example, the common cold) and fungal infections (such as ringworm). Your doctor can best determine if an antibiotic is right for your condition.

Antibiotics Introduction

• ChemotherapyChemotherapy, or the use of chemical agents to , or the use of chemical agents to destroy cancer cells, is a mainstay in the treatment destroy cancer cells, is a mainstay in the treatment of malignancies. The possible role in treating illness of malignancies. The possible role in treating illness was discovered when the bone marrow suppressive was discovered when the bone marrow suppressive effect of nitrogen mustard was noted in the early effect of nitrogen mustard was noted in the early 1900's. Since that time, the search for drugs with 1900's. Since that time, the search for drugs with anticancer activity has continued, and the goal of anticancer activity has continued, and the goal of treatment with chemotherapy has evolved from relief treatment with chemotherapy has evolved from relief of symptoms to cure. A major advantage of of symptoms to cure. A major advantage of chemotherapy is its ability to treat widespread or chemotherapy is its ability to treat widespread or metastatic cancer, whereas surgery and radiation metastatic cancer, whereas surgery and radiation therapies are limited to treating cancers that are therapies are limited to treating cancers that are confined to specific areas. confined to specific areas.

• Chemotherapy is the use of drugs that kill rapidly Chemotherapy is the use of drugs that kill rapidly dividing cells to treat cancer. Chemotherapy drugs are dividing cells to treat cancer. Chemotherapy drugs are toxic to cancer cells, which take in the drugs as they toxic to cancer cells, which take in the drugs as they multiply. Once inside the cells, the drug kills the cell or multiply. Once inside the cells, the drug kills the cell or prevents it from dividing and forming new cells. prevents it from dividing and forming new cells.

• Chemotherapy may consist of a single medication or a Chemotherapy may consist of a single medication or a combination of drugs administered intravenously or combination of drugs administered intravenously or orally. Most patients with active, symptomatic myeloma orally. Most patients with active, symptomatic myeloma (stage II or III) are initially treated with some form of (stage II or III) are initially treated with some form of chemotherapy. chemotherapy.

• There are several chemotherapy regimens that myeloma There are several chemotherapy regimens that myeloma patients may receive, including: patients may receive, including:

• Conventional chemotherapyConventional chemotherapy• High-dose chemotherapy with stem cell transplantationHigh-dose chemotherapy with stem cell transplantation• Salvage therapySalvage therapy

• Almost all chemotherapy agents currently Almost all chemotherapy agents currently available kill cancer cells by affecting DNA available kill cancer cells by affecting DNA synthesis or function, a process that occurs synthesis or function, a process that occurs through the cell cycle. Each drug varies in the through the cell cycle. Each drug varies in the way this occurs within the cell cycle. way this occurs within the cell cycle.

• The major categories of chemotherapy agents The major categories of chemotherapy agents are alkylating agents, antimetabolites, plant are alkylating agents, antimetabolites, plant alkaloids, antitumor antibiotics, and steroid alkaloids, antitumor antibiotics, and steroid hormones. Each drug is categorized according hormones. Each drug is categorized according to their effect on the cell cycle and cell to their effect on the cell cycle and cell chemistry. chemistry.

• Alkylating agentsAlkylating agents kill cells by directly attacking DNA. Alkylating agents may kill cells by directly attacking DNA. Alkylating agents may be used in the treatment of chronic leukemias, Hodgkin's disease, be used in the treatment of chronic leukemias, Hodgkin's disease, lymphomas, and certain carcinomas of the lung, breast, prostate and ovary. lymphomas, and certain carcinomas of the lung, breast, prostate and ovary. CyclophosphamideCyclophosphamide is an example of a commonly used alkylating agent. is an example of a commonly used alkylating agent.

• NitrosoureasNitrosoureas act similarly to akylating agents and also inhibit changes act similarly to akylating agents and also inhibit changes necessary for DNA repair. These agents cross the blood-brain barrier and are necessary for DNA repair. These agents cross the blood-brain barrier and are therefore used to treat brain tumors, lymphomas, multiple myeloma, and therefore used to treat brain tumors, lymphomas, multiple myeloma, and malignant melanoma. malignant melanoma. Carmustine (BCNU)Carmustine (BCNU) and and lomustine (CCNU)lomustine (CCNU) are the are the major drugs in this category. major drugs in this category.

• AntimetabolitesAntimetabolites are that drugs block cell growth by interfering with certain are that drugs block cell growth by interfering with certain activities, usually DNA synthesis. Once ingested into the cell they halt normal activities, usually DNA synthesis. Once ingested into the cell they halt normal development and reproduction. All drugs in this category affect the cell during development and reproduction. All drugs in this category affect the cell during the "S" phase of the cell cycle. Antimetabolites may be used in the treatment the "S" phase of the cell cycle. Antimetabolites may be used in the treatment of acute and chronic leukemias, choriocarcinoma, and some tumors of the of acute and chronic leukemias, choriocarcinoma, and some tumors of the gastrointestinal tract, breast and ovary. . Examples of commonly used gastrointestinal tract, breast and ovary. . Examples of commonly used antimetabolites are antimetabolites are 6-mercaptopurine6-mercaptopurine and 5-fluorouracil (5FU). and 5-fluorouracil (5FU).

• Antitumor antibioticsAntitumor antibiotics are a diverse group of compounds. In general, they are a diverse group of compounds. In general, they act by binding with DNA and preventing RNA synthesis. These agents are act by binding with DNA and preventing RNA synthesis. These agents are widely used in the treatment of a variety of cancers. The most commonly used widely used in the treatment of a variety of cancers. The most commonly used drugs in this group are drugs in this group are doxorubicindoxorubicin (Adriamycin), (Adriamycin), mitomycin-Cmitomycin-C, and , and bleomycinbleomycin. .

• An antisepticAn antiseptic is a substance which is a substance which inhibits the growth and development of inhibits the growth and development of microorganisms. For practical purposes, microorganisms. For practical purposes, antiseptics are routinely thought of as antiseptics are routinely thought of as topical agents, for application to skin, topical agents, for application to skin, mucous membranes, and inanimate mucous membranes, and inanimate objects, although a formal definition objects, although a formal definition includes agents which are used includes agents which are used internally, such as the urinary tract internally, such as the urinary tract antiseptics.antiseptics.

• Antiseptics are a diverse class of drugs which are Antiseptics are a diverse class of drugs which are applied to skin surfaces or mucous membranes applied to skin surfaces or mucous membranes for their anti-infective effects. This may be either for their anti-infective effects. This may be either bacteriocidal or bacteriostatic. Their uses include bacteriocidal or bacteriostatic. Their uses include cleansing of skin and wound surfaces after injury, cleansing of skin and wound surfaces after injury, preparation of skin surfaces prior to injections or preparation of skin surfaces prior to injections or surgical procedures, and routine disinfection of surgical procedures, and routine disinfection of the oral cavity as part of a program of oral the oral cavity as part of a program of oral hygiene. Antiseptics are also used for disinfection hygiene. Antiseptics are also used for disinfection of inanimate objects, including instruments and of inanimate objects, including instruments and furniture surfaces.furniture surfaces.

•DisinfectantsDisinfectants•are are antimicrobial agents that are applied to that are applied to non-living objects to destroy non-living objects to destroy microorganisms, the process of which is known as , the process of which is known as disinfection.disinfection. Disinfectants should generally Disinfectants should generally be distinguished from be distinguished from antibiotics that that destroy microorganisms within the body, destroy microorganisms within the body, and from and from antisepticsantiseptics, which destroy , which destroy microorganisms on living tissue. microorganisms on living tissue. SanitizersSanitizers are substances that reduce the number of are substances that reduce the number of microorganisms to a safe level. The main microorganisms to a safe level. The main difference between a sanitizer and a difference between a sanitizer and a disinfectant is that at a specified use disinfectant is that at a specified use dilution, the disinfectant must have a dilution, the disinfectant must have a higher kill capability for pathogenic higher kill capability for pathogenic bacteria compared to that of a sanitizer. bacteria compared to that of a sanitizer. Bacterial endospores are most resistant to Bacterial endospores are most resistant to disinfectants, however some viruses and disinfectants, however some viruses and bacteria also possess some tolerance.bacteria also possess some tolerance.

• Types of disinfectantsTypes of disinfectants• Disinfection liquid attached to hospital bedDisinfection liquid attached to hospital bed• AlcoholsAlcohols• AlcoholsAlcohols, usually , usually ethanolethanol or or isopropanolisopropanol, are wiped over benches and skin and allowed , are wiped over benches and skin and allowed

to evaporate for quick disinfection. They have wide microbiocidal activity, are non to evaporate for quick disinfection. They have wide microbiocidal activity, are non corrosive, but can be a fire hazard. They also have limited residual activity due to corrosive, but can be a fire hazard. They also have limited residual activity due to evaporation, which results in brief contact times, and have a limited activity in the evaporation, which results in brief contact times, and have a limited activity in the presence of organic material. Alcohol is not effective against fungal or bacterial spores.presence of organic material. Alcohol is not effective against fungal or bacterial spores.

• AldehydesAldehydes• Aldehydes, such as Aldehydes, such as GlutaraldehydeGlutaraldehyde, have a wide microbiocidal activity and are , have a wide microbiocidal activity and are

sporocidal and fungicidal. They are partly inactivated by organic matter and have slight sporocidal and fungicidal. They are partly inactivated by organic matter and have slight residual activity.residual activity.

• HalogensHalogens• ChloramineChloramine is used in drinking water treatment instead of chlorine because it produces is used in drinking water treatment instead of chlorine because it produces

fewer disinfection byproducts. fewer disinfection byproducts. • ChlorineChlorine is used to disinfect swimming pools, and is added in small quantities to is used to disinfect swimming pools, and is added in small quantities to

drinking waterdrinking water to reduce waterborne diseases. to reduce waterborne diseases. • IodineIodine is usually dissolved in an organic solvent or as is usually dissolved in an organic solvent or as Lugol's iodineLugol's iodine solution. It is used solution. It is used

in the in the poultrypoultry industry. It is added to the birds' drinking water. Although no longer industry. It is added to the birds' drinking water. Although no longer recommended because it increases scar tissue formation and increases healing time, recommended because it increases scar tissue formation and increases healing time, tincture of iodinetincture of iodine has also been used as an antiseptic for skin cuts and scrapes. has also been used as an antiseptic for skin cuts and scrapes.

Disinfection liquid attached to hospital bed

• Relative effectiveness of disinfectantsRelative effectiveness of disinfectantsOne way to compare disinfectants is to compare One way to compare disinfectants is to compare how well they do against a known disinfectant how well they do against a known disinfectant and rate them accordingly. Phenol is the and rate them accordingly. Phenol is the standard, and the corresponding rating system standard, and the corresponding rating system is called the "is called the "Phenol coefficientPhenol coefficient". The ". The disinfectant to be tested is compared with disinfectant to be tested is compared with phenol on a standard microbe (usually phenol on a standard microbe (usually Salmonella typhiSalmonella typhi or or Staphylococcus aureusStaphylococcus aureus). ). Disinfectants that are more effective than Disinfectants that are more effective than phenol have a coefficient > 1. phenol have a coefficient > 1.

Examples of UV sensors for water disinfection monitoring

• Materials:Materials:• 8 nutrient agar plates 8 nutrient agar plates • 1 thumb forceps1 thumb forceps• 1 bent glass rod 1 bent glass rod • 2 sterile 1mLpipettes2 sterile 1mLpipettes• Alcohol for sterilizationAlcohol for sterilization• Metric rulerMetric ruler• Antibiotic sensitivity disksAntibiotic sensitivity disks• Sterile paper disksSterile paper disks• Assorted antisepticsAssorted antiseptics• Ultraviolet lampsUltraviolet lamps• Nutrient both cultures of E.Coli and Bacillus cereusNutrient both cultures of E.Coli and Bacillus cereus

• We have two methods:We have two methods:

• 1-Disk diffusion1-Disk diffusion

• R=rangeR=range

• I = intermediateI = intermediate

• S= senisivityS= senisivity

AntibioticAntibioticRRIISS

GentamyciGentamycinn

Less Less 1515

16-16-1919

more 20more 20

• 2- Tube dilution2- Tube dilution

• MIC (minimium inhibition con.)MIC (minimium inhibition con.)

http://en.wikipedia.org/wiki/Disinfectant

1.http://mic.sgmjournals.org/cgi/content/full/152/4/989

1.^ EPA's Registered Sterilizers, Tuberculocides, and Antimicrobial Products Against HIV-1, and Hepatitis B and Hepatitis C Viruses. (Obtained January 4, 2006)