Basic Microbiology. By the end of this chapter, you will be able to: Introduction. What are Micro-organisms? Chapter 3

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1 Chapter 3 Basic Microbiology By the end of this chapter, you will be able to: l Name the types of micro-organisms that may be found in clean rooms l List the ways in which microbial contamination is carried and transferred l Name three types of bacteria that contaminate clean rooms and explain the sources of contamination l Define the terms bacteria, moulds, yeasts, spores l List ways in which microorganisms are controlled Introduction Micro-organisms are with us in our daily lives and in healthy individuals usually present no threat to life. However aseptic products are prepared for patients whose health is compromised and the introduction of microorganisms could kill or seriously harm the patient. This chapter examines the different types of micro-organisms that exist, where they come from, how they are transported and how we can control them in an aseptic suite. What are Micro-organisms? Micro-organisms are living organisms that are so small they cannot be seen with the human eye. They are found everywhere and always occur where other forms of life are present. The human body is a rich source of micro-organisms. Some micro-organisms are useful, for example: l For soil fertility l As part of the food chain l In the production of wine l In the production of antibiotics l In the production of bread Chapter 3: Basic Microbiology 1

2 Aseptic Processing But micro-organisms can also cause diseases or death. The presence of micro-organisms in an aseptic unit can have fatal consequences. Although we can t see them, they seem to get everywhere! Micro-organisms can be carried and transferred in a number of ways: l By Air l On Skin l Through touch l In water l In droplets l On machinery l On raw materials Types of Micro-organism Bacteria, moulds, yeasts and viruses are all types of micro-organism. Bacteria are the most common form of microbial contamination in clean rooms. These are unicellular (single celled) organisms. They can range in size from microns, but are usually 1 2 microns. (One micron is a millionth of a metre). Bacteria are either rod shaped (bacillus) or spherical (coccus). Bacilli may have short hairs (cilia) or long hairs (flagella). e.g. Listeria is a flagellate bacterium (i.e. has flagella) and can contaminate food. Bacteria produce pyrogens. These are endotoxins which, if injected into the bloodstream can cause a rise in temperature which can be fatal. Pyrogens are a particular hazard as they are resistant to heat and are not destroyed by autoclaving. Moulds are a form of fungus and cause cottony growth on organic substances. They grow in bread and are often found in air conditioning units. The second most common form of microbial contamination in clean rooms, they range from 5-8 microns in size. An important application of moulds is in the production of antibiotics, but on the negative side, they are also responsible for food spoilage, mildew and dry rot. Moulds can be brought into a unit during building work e.g. in plaster dust, or as a result of contact with animals. Yeasts are a rare contaminant in clean rooms. Like moulds, yeasts are a form of fungus. They are from 5-8 microns in size. On the positive side, yeasts are used in the production of alcohol, bread and vitamins. On the negative side, they can cause infections such as thrush (Candida), and as with any micro-organism, their presence in an aseptic unit can be fatal. As with moulds, yeasts can be brought into a unit during building work e.g. in plaster dust and as a result of contact with animals. 2 Chapter 3: Basic Microbiology

3 Chapter 3 Basic Microbiology Viruses are much smaller than bacteria and can only be viewed with the aid of an electron microscope. They grow inside other cells and cannot multiply outside a host cell. A new viral cell causes the death of the host cell. Viruses spread from cell to cell in the tissue and eventually disease becomes apparent. Cold, flu, chickenpox, hepatitis and HIV are all examples of diseases caused by viruses. Information We don t routinely test for viruses in clean rooms. Spores. Fungi, including moulds and yeasts, and certain bacteria can produce spores. These are a dormant form of microorganism that are more resistant to heat and disinfectants due to the presence of a protective outer coat. Information Spraying with alcohol and some disinfectants does not destroy spores. Chapter 3: Basic Microbiology 3

4 Aseptic Processing Sources of Contamination The table shows types of organisms that contaminate clean rooms and where they come from. Organism Group Status Source Likely Source of Contamination Staphylococcus (bacteria) Living Non-sporing Personnel Skin, hair, wounds, abscesses, clothing and dust. Poor disinfection can cause transfer into clean areas. Bacillus (bacteria) Living Sporing Personnel, soil, water, vegetation and foodstuffs Dust, air, cardboard, paper, water, mops and clothing. Inadequate cleaning/ disinfection. Poor transfer disinfection. Pseudomonas (bacteria) Living Personnel, water, plants, animals and insects Hot and cold water systems, sinks, drain and incorrectly prepared disinfectant solutions. Moulds Living Sporing Buildings, particularly walls and ceilings Soil, dust, untreated cardboard and paper. Inadequate cleaning. Poor transfer disinfection. Yeasts Living Sporing Personnel and foodstuffs Inadequate cleaning. Poor Transfer and disinfection. 4 Chapter 3: Basic Microbiology

5 Chapter 3 Basic Microbiology Test Yourself Without looking at the Sources of Contamination table, can you remember the likely sources of contamination? You should be able to list at least 10. Notes: Chapter 3: Basic Microbiology 5

6 Aseptic Processing Controlling Micro-organisms So what do we need to control? l Premises fabric of the facility l Plant and equipment air quality and movement l Products possible source of contamination l People definite source of contamination! l Processes everything we do in the clean room! The levels of micro-organisms are controlled by using the following: 1. Air handling and clean room design l HEPA filter l Positive pressure air cascades 2. Contamination control l Hygiene l Gowning and gloving l Cleaning and disinfecting 3. Staff behaviours and attitudes l Adherence to Standard Operating Procedures (SOPs) l Good techniques and practices 6 Chapter 3: Basic Microbiology

7 Chapter 3 Basic Microbiology Task Find out how the levels of micro-organisms are measured in your unit. What were the most recent findings? Micro-organism levels are measured by:... Most recent findings on / / (insert date) were:... Questions Q1 What types of micro-organisms are most commonly found in clean rooms? (5) Chapter 3: Basic Microbiology 7

8 Aseptic Processing Q2 What type of micro-organism is a rare contaminant in clean rooms? (1) Q3 Which type of micro-organism is not routinely tested for in clean rooms? (1) 8 Chapter 3: Basic Microbiology

9 Chapter 3 Basic Microbiology Q4 What two types of micro-organism can be brought into the clean room as a result of contact with animals? (1) Q5 What are pyrogens? (2) Chapter 3: Basic Microbiology 9

10 Aseptic Processing Q6 What type of micro-organism is often found in air conditioning units? (1) Q7 List three types of micro-organism that can produce spores. (1) 10 Chapter 3: Basic Microbiology