Lingkungan biotik dan abiotik Lingkungan abiotik fisik suhu

Lingkungan : biotik dan abiotik Lingkungan abiotik : • fisik : suhu, kadar air media, nilai osmosis media, radiasi, penghancuran sel secara mekanik • kimia : bakteriostatik, antiseptik, bakterisida, germisida, desinfektan

Lingkungan abiotik: fisik Suhu Batas minimum dan maksimum suhu lingkungan yang mempengaruhi proses fisiologi • Bakteri termofil (politermik) : bakteri yang mampu tumbuh pada suhu 40 o. C – 80 o. C dengan suhu optimum 55 o. C-65 o. C • Bakteri mesofil (mesotermik) : bakteri yang mampu tumbuh baik pada kisaran suhu 5 o. C – 60 o. C dengan suhu optimum 25 -40 o. C • Bakteri psikrofil (oligotermik) : bakteri yang mampu tumbuh pada kisaran suhu 0 o. C sampai 30 o. C dengan suhu optimum 10 -20 o. C.

Temperature Figure 6. 1

Psychrotrophs Figure 6. 2

Bakteri yang mampu tumbuh dengan kisaran suhu minimum dan optimum yang sempit : stenotermik >< euritermik • Gonococcus : hidup dalam kisaran 3040 o. C • E coli tumbuh baik pada kisaran 8 -46 o. C • Bakteri yang dipiara sedikit diatas suhu maksimum dan dibawah suhu minimum tidak segera mati, melainkan dalam kondisi dormancy

Kadar air media enzim untuk kegiatan metabolisme umumnya termasuk kelompok hidrolase Nilai osmosis media larutan isotonik larutan hipertonik : plasmolisis larutan hipotonik : plasmoptisis Pengaruh radiasi bakteri fotoototrof dan fotoheterotrof mampu hidup pada sinar tampak (390 nm – 760 nm). Radiasi sinar gelombang pendek (sinar X, UV) menyebabkan kematian sel, bakteri mengalami mutasi gen.

Lingkungan abiotik: kimia Antiseptik, bakteriostatik : Zat kimia yang mampu menghambat pertumbuhan bakteri, tidak membunuh bakteri Germisida, bakterisida, desinfektan : Zat kimia yang dapat membunuh bakteri Zat antiseptik dan bakterisida tidak mampu membunuh spora bakteri dan bakteri tahan asam

Kerusakan bakteri karena zat kimia disebabkan : oksidasi, koagulasi protein dan penurunan tegangan permukaan sel. Konsentrasi zat kimia dan lama persentuhan mempengaruhi kelompok antiseptik atau desinfektan. Larutan fenol 5% = desinfektan, larutan fenol 1% = antiseptik, larutan fenol 0. 5% = sumber karbon Pseudomonas

CHEMICAL DISINFECTION A SATISFACTORY AGENT SHOULD: • Be active against a wide range of organisms and spores. Only few are truly sterilizer • Have a rapid action • Should not be toxic or irritant to the skin • Should be Persistent There is no one disinfectant which can be used to kill all micro-organisms in all situations.

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Types of Chemical disinfectants • Inorganic: – Iodine – Chlorine • Organic: – Alcohols – Aldehydes – Phenols – Cationic surface-active agents

Inorganic disinfectants The halogens: Chlorine and Iodine • Have a rapid action against vegetative organisms and spores= true sterilizers • Their action is annulled by foreign organic material membatalkan

Iodine disinfectants The broadest spectrum of all topical anti-infectives, with action against bacteria, fungi, viruses, spores, protozoa, and yeasts. • Tincture iodine: – 2. 5% iodine & 2. 5% potassium iodide in 90% ethanol. – Best skin disinfectant – Irritating to raw surfaces: due to its alcoholic component – Allergic dermatitis • Iodophors: Solutions of iodine in non-ionic detergents= Povidone iodine= Betadine – Less irritating and less staining – Less disinfectant than tincture

Chlorine disinfectants • • Powerful, Disinfect water Particularly active against viruses Concentrated solutions too corrosive Usually diluted with a compatible detergent

Organic Disinfectants • Alcohols: bactericidal: 50 -70% ethanol • Aldehydes: – Formalin: irritant, powerful=sterilizer – Glutaraldehyde: less irritant, not volatile, more rapid action. • Phenols: continued activity in organic matter as human excreta. – – – Phenol: Toxic, expensive Cresols: Lysol Chloroxylenol: Dettol Chlorhexidine: Hibitane- Alkanol Hexachlorophane • Cationic surface-active agents: – Cetrimide: Cetavlon

Alcohol • Isopropyl Alcohol 70% (or Ethyl Alcohol 90%) ADVANTAGES: • Causes protein denaturation, cell lysis, and metabolic interruption. • Degreases the skin. DISADVANTAGES: • Ineffective against bacterial spores and poorly effective against viruses and fungi.

Glutaraldehyde (Cidex) Cold Sterilization: • Instruments must be dry before immersion. • Glutaraldehyde is bactericidal, fungicidal, viricidal, and sporicidal • Sterilization: a 10 hour immersion. This prolonged chemical action can be more detrimental to surgical instruments. • 3 hours exposure time is needed to destroy spores. • If the instruments need to be "disinfected" only, cold sterilization is okay as disinfection will take place in only 10 minutes.

Lysoformin • Formaldehyde & glutaral • Lysoformin: liquid concentrate with which any dilution required can be made by simply adding water (20 ml + 4 -8 L) • The timing depends on the concentration used: – flexible endoscopes – deactivation of HBV & HIV 1. 5 % - 30 min 2. 0 % - 15 min • Used for heat labile instruments and cleaning • Does not harm metal instruments

Chlorhexidine Gluconate Hibitane vs Alkanol Broadest spectrum Better residual activity than iodophors Occasional skin sensitivity ADVANTAGES: Rapid action Residual activity is enhanced by repeated use Less susceptible to organic inactivation than povidone iodine DISADVANTAGES: Occasional skin sensitivity. Inactive against bacterial spores Activity against viruses and fungi is variable and inconsistent May harm metal instruments

Gaseous Disinfection Ethylene Oxide Sterilization: EO Gas • Colorless gas, available as cartridges • Toxic and flammable, Odor similar to ether • Has an extremely well penetration, even through plastics • Microorganism destruction is caused by a chemical reaction • Effective sterilization is dependent on concentration of gas, exposure time, temperature, and relative humidity • Powerful sterilizer: Kills all known viruses, bacteria (including spores), and fungi

EO Gas Sterilizer • Is used in large hospitals, as it is expensive, dangerous, needs more expertise. • Used for heat sensitive instruments: fabrics, plastics, suture material, lenses, endoscopes, electrical equipment and finely sharpened instruments. • At 20°C-25°C: sterilization takes 18 hours • At 50°C-60°C: sterilization takes 4 hours • In Demerdash: The average of the cycle is 8 -14 hours