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Minimizing Equipment and Technique-Related Hazards


1. Pipettes

Mouth pipetting must be banned at all times. Pipetting devices should be inspected routinely for leakage and services and replaced as necessary. When discharging infectious material from a pipette, it is important to minimize the formation of aerosols; The last drop in the pipette should not be forced out but left in the pipette, care should be taken to avoid bubbling when mixing liquids with pipettes, it may advisable to discharge the liquid onto the side of the container. Contaminated pipettes should always be discarded into disinfectant fluid which is prepared daily. Broken and chipped pipettes should be discarded.

2. Hypoderemic needles and syringes

These are the most hazardous pieces of equipment in common use. Surveys have shown that at least one-quarter of overt accidents which result in infection were caused by these instruments. Many inoculations result during experiments with animals, others occur during transfer of infected material by syringes. Many needlestick accidents occur when the needle is being disconnected from the syringe so that blood may be discharged into its specimen container gently to avoid haemolysis. Some hospitlas and institutions ban disconnection, but other solutions are available such as needleguards which permit the safe disconnection and recapping of needles, needle forceps, and vacuum collection outfits. It is important that used needles are disposed properly into harden "sharps containers" which are then autoclaved before disposal. These "sharps containers" should be available where they are needed.

3. Centrifugation

Infectious material may be dispersed by a centrifuge either through broken tubes or other means such as through the threads of the tubes and caps. Sealed centrifuge buckets should be used when centrifuging infectious material. Care should be taken to ensure that the centrifuge tubes are not cracked or flawed. Tubes should not be more than three-quarters full, especially if angle centrifuges are used. Tubes should be capped and they and the buckets should be balanced carefully to avoid vibration which may lead to breakage. Material containing agents which are particularly likely to cause laboratory infections should centrifuged in sealed centrifuge buckets which are subsequently opened in a safety cabinet.

4. Pouring infectious material

Pouring of the supernatant after centrifuging cultures or viruses, NPA and diarrhoeal specimens is common practice. These fluids are usually poured into disinfectant. Two hazards may arise: production of aerosols, and contamination of the outside of the tube from which the material is poured. These hazards may be minimized by pouring infected fluids into a funnel, and that small strips of blotting paper be used to wipe the rims of tubes after pouring.

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Collection, Transport and Receipt of Infectious Materials