Pengendalian Mikroorganisme Kuliah ke-14 Mikrobiologi

Cara Pengendalian Mekanisme pengendalian dapat secara fisik atau kimia Mungkin kombinasi keduanya Metode Fisik Panas lembab Panas kering Suhu rendah Irradiasi Filtrasi Pemusnahan secara mekanis Metode Kimia Menggunakan berbagai jenis bahan kimia antimikroba. Bahan kimia bergantung pada keadaan dan tingkat pengendalian yang diperlukan.

Cara Pengendalian Prinsip pengendalian Sterilisasi Disinfeksi Pemusnahan selluruh mikroorganisme Barang yang steril harus benar-benar bebas dari mikroba, endospora dan virus Dapat dicapai melalui filtrasi, pemanasan, bahan kimia, dan irradiasi Disinfeksi Memusnahkan kebanyakan patogen Beberapa mikroba yang hidup masih ada Disinfektan = digunakan pada objek dan permukaan yang mati Antiseptik = digunakan pada jaringan hidup Pasteurisasi Perlakuan panas secara singkat digunakan untuk mengurangi organisme yang menyebabkan busuknya makanan. Permukaan dapat dipasteurisasi.

Cara Pengendalian Prinsip pengendalian Dekontaminasi Perlakuan untuk mengurangi patogen sampai level aman. Degerming Mekanisme yang digunakan untuk mengurangi jumlah mikroba pada suatu daerah. Khususnya kulit Sanitasi Secara tidak langsung mengurangi populasi mikroba dalam jumlah besar. Ini bukan cara pengendalian yang spesifik. Preservasi Proses yang digunakan untuk menunda kebusukan bahan yang tidak bertahan lama. Sering penambahan bahan-bahan penghambat pertumbuhan

Cara Pengendalian Pertimbangan situasi Metode pengendalian mikroba sangat bervariasi Bergantung pada situasi dan tingkat pengendalian yang diperlukan Kehidupan sehari-hari Rumah sakit Laboratorium microbiologi Makanan dan fasilitas produksi makanan Perlakuan air

Cara Pengendalian Kehidupan sehari-hari Mencuci dengan sabun dan deterjen mencapai pengendalian rutin. Hand washing single most important step to achieving control Sabun bertindak sebagai bahan pembasah. Aids in mechanical removal of microorganisms Memusnahkan sejumlah organisme dari lapisan kulit paling luar. Mikroorganisme yang normal biasanya tidak berpengaruh karena menempati lapisan paling dalam.

Cara Pengendalian Rumah sakit Meminimalisasi populasi mikroba sangat penting. Disebabkan bahaya infeksi nosocomial Pasien lebih rentan terhadap infeksi Patogen lebih sering ditemui pada pembangunan rumah sakit. Berbagai organisme mengembangkan ketahanan antimikroba disebabkann konsentrasi antibitiok yang tinggi. Peralatan harus disterilisasi untuk menghindari infeksi ke dalam jaringan yang lebih dalam.

Cara Pengendalian Laboratorium Mikrobiologi Menggunakan metode pengendalian yang akurat Untuk memusnahkan kontaminasi mikroba terhadap sampel percobaan dan lingkungan Teknik aseptik dan media steril digunakan untuk pertumbuhan Menghilangkan organisme yang tidak diiinginkan Bahan yang terkontaminasi diberi perlakuan untuk dibuang Menghilangkan kontaminasi lingkungan

Cara Pengendalian Makanan dan fasilitas makanan Mempertahankan kualitas makanan; ditingkatkan melalui pencegahan pertumbuhan dan kontaminasi mikroba. Dicapai melalui pemusnahan organisme secara fisik dan kimia physical Perlakuan panas adalah mekanisme yang paling umum dan paling dpat dipercaya. Irradiation dibuktikan untuk memperlakukan beberapa makanan. Bahan kimia mencegah pembusukan. Resiko keracunan

Cara Pengendalian Fasilitas perlakuan air (water treatment) Memastikan air minum aman Chlorin biasanya digunakan untuk mendesinfeksi air. Beberapa organisme tahan terhadap bahan kimia desinfektan.

Panas sebagai Pengendalian Perlakuan panas sangat berguna untuk pengendalian mikroba Relatif cepat, dapat dipercaya, aman, dan tidak mahal. Panas dapat digunakan untuk sterilisasi dan desinfeksi. Metode panas, yaitu: Panas lembab Panas kering

Panas sebagai Pengendalian Panas lembab Menghancurkan melalui koagulasi protein secara irreversible Panas lembab, termasuk: Pendidihan Pasteurisasi Tekanan uap

Panas sebagai Pengendalian Pendidihan (100 °C) Destroys most microorganisms and viruses Not effective means of sterilization Does not destroy endospores Pasteurisasi Pasteur developed to avoid spoilage of wine Does not sterilize but significantly reduces organisms Used to increase shelf life of food Most protocols employ HTST method Heated to 72°C and held for 15 seconds Other protocol UHT Heated to 140°C - 150°C, held for several seconds then rapidly cooled

Panas sebagai Pengendalian Tekanan uap Autoclave used to sterilize using pressurized steam Heated water  steam  increased pressure Preferred method of sterilization Achieves sterilization at 121°C and 15psi in 15 minutes Effective against endospores Flash autoclaving sterilizes at 135°C and 15psi in 3 minutes Prions destroyed at 132°C and 15psi for 4.5 hours

Panas sebagai Pengendalian Panas kering Not as effective as moist heat Sterilization requires longer times and higher temperatures 200°C for 1.5 hours vs. 121°C for 15 minutes for moist Incineration method of dry heat sterilization Oxidizes cell to ashes Used to destroy medical waste and animal carcasses Flaming laboratory inoculation loop incinerates organism Results in sterile loop

Metode Fisik lainnya Heat sensitive materials require other methods of microbial control Filtration Irradiation High-pressure treatment

Metode Fisik lainnya Filtration Filtration of air Membrane filtration used to remove microbes from fluids and air Liquid filtration Used for heat sensitive fluids Membrane filters allow liquids to flow through Traps microbes on filter Depth filters trap microbes using electrical charge Filtration of air High efficiency particulate air (HEPA) filter remove nearly all microbes from air Filter has 0.3µm pores to trap organisms

Metode Fisik lainnya Radiation Electromagnetic radiation Energy released from waves Based on wavelength and frequency Shorter wavelength, higher frequency = more energy Range of wavelength is electromagnetic spectrum Radiation can be ionizing or non-ionizing

Metode Fisik lainnya Ionizing radiation Radiation able to strip electrons from atoms Three sources Gamma radiation X-rays Electron accelerators Causes damage to DNA and potentially to plasma membrane Used to sterilize heat resistant materials Medical equipment, surgical supplies, medications Some endospores can be resistant

Metode Fisik lainnya Ultraviolet radiation Non-ionizing radiation Only type to destroy microbes directly Damages DNA Causes thymine dimers Used to destroy microbes in air, drinking water and surfaces Limitation Poor penetrating power Thin films or coverings can limit effect

Metode Fisik lainnya High pressure processing Used in pasteurization of commercial foods Does not use high temperatures Employs high pressure Up to 130,000 psi Destroys microbes by denaturing proteins and altering cell membrane permeability

Metode Kimia Chemicals can be used to disinfect and sterilize Called germicidal chemicals Reacts with vital cell sites Proteins DNA Cell membrane

Metode Kimia Potency of chemicals Formulations generally contain more than one antimicrobial agent Regulated by FDA Antiseptics EPA Disinfectants Germicidal agents grouped according to potency Sterilants = Destroy all microorganisms High-level disinfectants Destroys viruses and vegetative cells, Not endospores Intermediate-level disinfectants Kills vegetative cells fungi, most viruses, Low-level disinfectants Removes fungi, vegetative bacteria and enveloped viruses Not mycobacteria, naked viruses or endospores

Metode Kimia Selecting appropriate chemical Points to consider Toxicity Benefits must be weighed against risk of use Activity in presence of organic material Many germicides inactivated in presence of organic matter Compatibility with material being treated Liquids cannot be used on electrical equipment Residue Residues can be toxic or corrosive Cost and availability Storage and stability Concentrated stock relieves some storage issues Environmental risk Is germicidal agent harmful to environment

Metode Kimia Classes of chemicals Germicides represent a number or chemical families Alcohols Aldehydes Biguanides Ethylene oxide Halogens Metals Ozone Peroxides Phenolics Quaternary ammonium compounds

Metode Kimia Alcohols Solutions of 60% - 80% isopropyl or ethyl alcohol kill vegetative bacteria and fungi Not effective against endospores and some naked viruses Mode of action Coagulation of proteins and essential enzymes Damage to lipid membranes Commonly used as antiseptic and disinfectant Limitations Evaporates quickly limiting contact time May damage material such as rubber and some plastics

Metode Kimia Aldehydes Destroy organisms by inactivating proteins and DNA 2% glutaraldehyde solution most widely used liquid sterilant Orthophthalaldehyde studied as alternative Formalin used to kill bacteria and inactivate viruses Also used for specimen preservation Formalin is solution made from formaldehyde

Metode Kimia Biguanides Most effective member of group is chlorhexidine Extensively used in antiseptics Relative low toxicity Destroys wide range of organisms

Metode Kimia Ethylene oxide Useful gaseous sterilant Mode of action Destroys microbes including endospores and viruses Mode of action Reacts with proteins Useful in sterilizing heat or moisture sensitive items Limitations Mutagenic and potentially carcinogenic

Metode Kimia Halogens Common disinfectants Mode of action Oxidizing proteins and other cell components Includes chlorine and iodine Chlorine Destroys all types of organisms and viruses Used as disinfectant Caustic to skin and mucous membranes Chlorine dioxide replacing chlorine in many applications Iodine Kills vegetative cells Not reliable with endospores Used in tincture or iodophore on skin

Metode Kimia Metal compounds Compounds combine with enzymes and proteins Interfering with function High concentrations of many metals toxic to human tissue Silver still used as disinfectant Creams containing silver sulfadiazine used to prevent secondary infections Also available on bandages for wound care

Chemicals as Control Ozone O3 Powerful oxidizing agent Unstable form of oxygen Powerful oxidizing agent Used as alternative to chlorine As disinfectant for drinking and waste water

Metode Kimia Peroxygens Includes hydrogen peroxide and peracetic acid Powerful oxidizing agents Readily biodegradable Less toxic than ethylene oxide and glutaraldehyde

Metode Kimia Hydrogen peroxide Peracetic acid Effectiveness depends on surface being treated Living tissue produce catalase enzyme Breaks down hydrogen peroxide to oxygen and water More effective on inanimate object Useful as disinfectant Leaves no residue Doesn’t damage most materials Hot solutions used in food industry Vapor-phase can be used as sterilant Peracetic acid More potent then hydrogen peroxide Effective on organic material Can be used on wide range of material

Metode Kimia Phenolics A.k.a carbolic acid One of the earliest disinfectants Now has limited use Active ingredient in Lysol Mode of action Destroy plasma membrane Denature proteins Kills most vegetative cells Can kill mycobacterium at high concentrations Not reliable on all groups of viruses Triclosan and hexachlorophene phenols used in soaps and lotions

Metode Kimia Quaternary ammonium compounds A.k.a Quats Cationic detergents Nontoxic Used to disinfect food preparation surfaces Mode of action Reduces surface tension Aids in removal of dirt and organic matter Facilitates mechanical removal of organisms Positive charge attracts Quats to negative charge of cell surface Reacts with membrane Destroys vegetative bacteria and enveloped viruses Not effective on endospores, mycobacteria and naked viruses

Pengawetan Produk yang tidak tahan lama Chemical preservatives Some chemical preservatives are used in non-food items Food preservatives must be non-toxic to humans Benzoic acid, propionic acids, nitrate are commonly used Nitrate Inhibits germination of C. botulinum endospores

Pengawetan Produk yang tidak tahan lama Low temperature storage Temperature dependent most microorganisms do not reproduce in ordinary refrigerator (0-7ºC) Freezing ice crystals can cause irreversible damage to many microorganisms (kills up to 50% growth) Freezing stops all growth, but may start to reproduce again once food is thawed

Pengawetan Produk yang tidak tahan lama Reducing water Salt/sugar Draw water out of cell Less available for microorganisms Drying Desiccation Removing water such as milk powder Salt cured meat

Pengawetan Produk yang tidak tahan lama Lyophilization Freeze drying Freeze food first followed by putting in vacuum

Antiseptics and disinfectants Metode Kimia Chemical Method Gas sterilants Ethylene oxide Antiseptics and disinfectants Germicidal chemical

Metode Kimia Chemical preservatives Numerous chemicals are used as preservatives Formaldehyde, Quats, and phenols Weak organic acids often used as food preservatives Benzoic, ascorbic and propionic acids Used in bread, cheese and juice Mode of action Alter cell membrane function Interfere with energy transformation Nitrates and nitrites used in processed meats Inhibits germination of endospores and growth of vegetative cells Have been shown to be potent carcinogen

Metode Kimia Low temperature storage Microbial growth is temperature dependent Low temperatures slow down or stop enzymatic reactions of mesophiles and thermophiles Some psychrophiles still able to grow Freezing means of food preservation Essentially stops microbial growth Irreversibly damages cell Kills up to 50% of microbes Remaing cells still pose potential threat

Metode Kimia Reducing water availability Decreasing water availability accomplished by salting or drying food Addition of salt increases environmental solutes Causes cellular plasmolysis Numerous bacteria can continue to grow in high salt environments Staphylococcus aureus can survive in high salt concentrations Desiccation or drying is often supplemented by other methods Salting Lyophilization (freeze drying) Widely used to preserve foods like coffee, milk and meats

Faktor yang mempengaruhi keefektifan pengendali mikroba Jumlah mikroba Pengaruh lingkungan Waktu Karakteristik mikroba

Microbial death curve

keterbatasan: Karakteristik Microba

Cara kerja agen pengendali mikroba Merubah permeabilitas membran Merusak protein Merusak asam nukleat

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